From nobody Thu Apr 2 18:49:56 2026 Received: from frasgout13.his.huawei.com (frasgout13.his.huawei.com [14.137.139.46]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AD331423A77; Thu, 26 Mar 2026 17:31:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=14.137.139.46 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774546268; cv=none; b=Tnp7xrMChQKkjHMBaEeLGhpGMhYMis0K8m7puRIy0twV9fB8dAatTjazuXE78d89qgWtWcFAwBsALj+UtEI8b5XnhAbcFGblfgD8jU3fVv1Bb8cKNIL3Ly1zgi5JXFMuJ4jrHHwVB22Jl4GGQ/ZVgHm75D3r+v2kMCvDSUOH45Q= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774546268; c=relaxed/simple; bh=GVA+pRSUc8z9qjax4x44siGnI0py36BZBiWSsjLmxJM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=co+IqDSo9lAvWvWDEpOjp+JQUKiZy03ZdB7QAAOscfATr4RtuWk0qZavvS1aJYaDBm4tUSAbu/9hEP3LGEZYYFI8TQVER4y0w0GyMxjUmr6LOudPyP6f21g9CndCscedumIc2XFoL49oJSyr13Aj+gM7biPXZN/+8jaiudR7aJQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=none smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=14.137.139.46 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.18.224.196]) by frasgout13.his.huawei.com (SkyGuard) with ESMTPS id 4fhW124LvJzpVVw; Fri, 27 Mar 2026 01:27:02 +0800 (CST) Received: from mail02.huawei.com (unknown [7.182.16.47]) by mail.maildlp.com (Postfix) with ESMTP id D24DE4056C; Fri, 27 Mar 2026 01:30:50 +0800 (CST) Received: from huaweicloud.com (unknown [10.204.63.22]) by APP1 (Coremail) with SMTP id LxC2BwB3Yu84bcVppGUvAQ--.1881S3; Thu, 26 Mar 2026 18:30:50 +0100 (CET) From: Roberto Sassu To: corbet@lwn.net, skhan@linuxfoundation.org, zohar@linux.ibm.com, dmitry.kasatkin@gmail.com, eric.snowberg@oracle.com, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, gregorylumen@linux.microsoft.com, chenste@linux.microsoft.com, nramas@linux.microsoft.com, Roberto Sassu Subject: [PATCH v4 01/13] ima: Remove ima_h_table structure Date: Thu, 26 Mar 2026 18:29:59 +0100 Message-ID: <20260326173011.1191815-2-roberto.sassu@huaweicloud.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260326173011.1191815-1-roberto.sassu@huaweicloud.com> References: <20260326173011.1191815-1-roberto.sassu@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: LxC2BwB3Yu84bcVppGUvAQ--.1881S3 X-Coremail-Antispam: 1UD129KBjvJXoWxtw4rXFW5Zw1fXr1DCry7trb_yoWxtw1kpa nFga42kF48XFyI9ryDAayqkrWrW3yUKr17Wws8Gw1Fk3ZrXr12gF15AFy2kFyfGFZYyF1I qrs0qr1YkwsYyrJanT9S1TB71UUUUUDqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUPqb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28IrcIa0xkI8VA2jI8067AKxVWUGw A2048vs2IY020Ec7CjxVAFwI0_Gr0_Xr1l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0rcxS w2x7M28EF7xvwVC0I7IYx2IY67AKxVW8JVW5JwA2z4x0Y4vE2Ix0cI8IcVCY1x0267AKxV W8Jr0_Cr1UM28EF7xvwVC2z280aVAFwI0_Gr0_Cr1l84ACjcxK6I8E87Iv6xkF7I0E14v2 6r4UJVWxJr1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2 WlYx0E2Ix0cI8IcVAFwI0_Jrv_JF1lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkE bVWUJVW8JwACjcxG0xvY0x0EwIxGrwACI402YVCY1x02628vn2kIc2xKxwCY1x0262kKe7 AKxVWrXVW3AwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02 F40E14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_GFv_Wr ylIxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVW8JVW5JwCI42IY6xIIjxv20xvEc7Cj xVAFwI0_Gr1j6F4UJwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI 0_Gr0_Cr1lIxAIcVC2z280aVCY1x0267AKxVW8Jr0_Cr1UYxBIdaVFxhVjvjDU0xZFpf9x 07jQ4SrUUUUU= X-CM-SenderInfo: purev21wro2thvvxqx5xdzvxpfor3voofrz/1tbiAgAEBGnEnS4TtgAFs8 Content-Type: text/plain; charset="utf-8" From: Roberto Sassu With the upcoming change of dynamically allocating and replacing the hash table, the ima_h_table structure would have been replaced with a new one. However, since the ima_h_table structure contains also the counters for number of measurements entries and violations, we would have needed to preserve their values in the new ima_h_table structure. Instead, separate those counters from the hash table, remove the ima_h_table structure, and just replace the hash table pointer. Finally, rename ima_show_htable_value(), ima_show_htable_violations() and ima_htable_violations_ops respectively to ima_show_counter(), ima_show_num_violations() and ima_num_violations_ops. Link: https://github.com/linux-integrity/linux/issues/1 Signed-off-by: Roberto Sassu --- security/integrity/ima/ima.h | 9 +++------ security/integrity/ima/ima_api.c | 2 +- security/integrity/ima/ima_fs.c | 19 +++++++++---------- security/integrity/ima/ima_kexec.c | 2 +- security/integrity/ima/ima_queue.c | 17 ++++++++++------- 5 files changed, 24 insertions(+), 25 deletions(-) diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index 0eea02ff04df..d759988fde45 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -323,12 +323,9 @@ int ima_lsm_policy_change(struct notifier_block *nb, u= nsigned long event, */ extern spinlock_t ima_queue_lock; =20 -struct ima_h_table { - atomic_long_t len; /* number of stored measurements in the list */ - atomic_long_t violations; - struct hlist_head queue[IMA_MEASURE_HTABLE_SIZE]; -}; -extern struct ima_h_table ima_htable; +extern atomic_long_t ima_num_entries; +extern atomic_long_t ima_num_violations; +extern struct hlist_head ima_htable[IMA_MEASURE_HTABLE_SIZE]; =20 static inline unsigned int ima_hash_key(u8 *digest) { diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_= api.c index 0916f24f005f..122d127e108d 100644 --- a/security/integrity/ima/ima_api.c +++ b/security/integrity/ima/ima_api.c @@ -146,7 +146,7 @@ void ima_add_violation(struct file *file, const unsigne= d char *filename, int result; =20 /* can overflow, only indicator */ - atomic_long_inc(&ima_htable.violations); + atomic_long_inc(&ima_num_violations); =20 result =3D ima_alloc_init_template(&event_data, &entry, NULL); if (result < 0) { diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_f= s.c index ca4931a95098..aaa460d70ff7 100644 --- a/security/integrity/ima/ima_fs.c +++ b/security/integrity/ima/ima_fs.c @@ -38,8 +38,8 @@ __setup("ima_canonical_fmt", default_canonical_fmt_setup); =20 static int valid_policy =3D 1; =20 -static ssize_t ima_show_htable_value(char __user *buf, size_t count, - loff_t *ppos, atomic_long_t *val) +static ssize_t ima_show_counter(char __user *buf, size_t count, loff_t *pp= os, + atomic_long_t *val) { char tmpbuf[32]; /* greater than largest 'long' string value */ ssize_t len; @@ -48,15 +48,14 @@ static ssize_t ima_show_htable_value(char __user *buf, = size_t count, return simple_read_from_buffer(buf, count, ppos, tmpbuf, len); } =20 -static ssize_t ima_show_htable_violations(struct file *filp, - char __user *buf, - size_t count, loff_t *ppos) +static ssize_t ima_show_num_violations(struct file *filp, char __user *buf, + size_t count, loff_t *ppos) { - return ima_show_htable_value(buf, count, ppos, &ima_htable.violations); + return ima_show_counter(buf, count, ppos, &ima_num_violations); } =20 -static const struct file_operations ima_htable_violations_ops =3D { - .read =3D ima_show_htable_violations, +static const struct file_operations ima_num_violations_ops =3D { + .read =3D ima_show_num_violations, .llseek =3D generic_file_llseek, }; =20 @@ -64,7 +63,7 @@ static ssize_t ima_show_measurements_count(struct file *f= ilp, char __user *buf, size_t count, loff_t *ppos) { - return ima_show_htable_value(buf, count, ppos, &ima_htable.len); + return ima_show_counter(buf, count, ppos, &ima_num_entries); =20 } =20 @@ -545,7 +544,7 @@ int __init ima_fs_init(void) } =20 dentry =3D securityfs_create_file("violations", S_IRUSR | S_IRGRP, - ima_dir, NULL, &ima_htable_violations_ops); + ima_dir, NULL, &ima_num_violations_ops); if (IS_ERR(dentry)) { ret =3D PTR_ERR(dentry); goto out; diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/im= a_kexec.c index 36a34c54de58..5801649fbbef 100644 --- a/security/integrity/ima/ima_kexec.c +++ b/security/integrity/ima/ima_kexec.c @@ -43,7 +43,7 @@ void ima_measure_kexec_event(const char *event_name) int n; =20 buf_size =3D ima_get_binary_runtime_size(); - len =3D atomic_long_read(&ima_htable.len); + len =3D atomic_long_read(&ima_num_entries); =20 n =3D scnprintf(ima_kexec_event, IMA_KEXEC_EVENT_LEN, "kexec_segment_size=3D%lu;ima_binary_runtime_size=3D%lu;" diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/im= a_queue.c index 319522450854..1f6515f7d015 100644 --- a/security/integrity/ima/ima_queue.c +++ b/security/integrity/ima/ima_queue.c @@ -32,11 +32,14 @@ static unsigned long binary_runtime_size; static unsigned long binary_runtime_size =3D ULONG_MAX; #endif =20 +/* num of stored measurements in the list */ +atomic_long_t ima_num_entries =3D ATOMIC_LONG_INIT(0); +/* num of violations in the list */ +atomic_long_t ima_num_violations =3D ATOMIC_LONG_INIT(0); + /* key: inode (before secure-hashing a file) */ -struct ima_h_table ima_htable =3D { - .len =3D ATOMIC_LONG_INIT(0), - .violations =3D ATOMIC_LONG_INIT(0), - .queue[0 ... IMA_MEASURE_HTABLE_SIZE - 1] =3D HLIST_HEAD_INIT +struct hlist_head ima_htable[IMA_MEASURE_HTABLE_SIZE] =3D { + [0 ... IMA_MEASURE_HTABLE_SIZE - 1] =3D HLIST_HEAD_INIT }; =20 /* mutex protects atomicity of extending measurement list @@ -61,7 +64,7 @@ static struct ima_queue_entry *ima_lookup_digest_entry(u8= *digest_value, =20 key =3D ima_hash_key(digest_value); rcu_read_lock(); - hlist_for_each_entry_rcu(qe, &ima_htable.queue[key], hnext) { + hlist_for_each_entry_rcu(qe, &ima_htable[key], hnext) { rc =3D memcmp(qe->entry->digests[ima_hash_algo_idx].digest, digest_value, hash_digest_size[ima_hash_algo]); if ((rc =3D=3D 0) && (qe->entry->pcr =3D=3D pcr)) { @@ -113,10 +116,10 @@ static int ima_add_digest_entry(struct ima_template_e= ntry *entry, INIT_LIST_HEAD(&qe->later); list_add_tail_rcu(&qe->later, &ima_measurements); =20 - atomic_long_inc(&ima_htable.len); + atomic_long_inc(&ima_num_entries); if (update_htable) { key =3D ima_hash_key(entry->digests[ima_hash_algo_idx].digest); - hlist_add_head_rcu(&qe->hnext, &ima_htable.queue[key]); + hlist_add_head_rcu(&qe->hnext, &ima_htable[key]); } =20 if (binary_runtime_size !=3D ULONG_MAX) { --=20 2.43.0 From nobody Thu Apr 2 18:49:56 2026 Received: from frasgout11.his.huawei.com (frasgout11.his.huawei.com [14.137.139.23]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C1CB4423153; 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dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.18.224.196]) by frasgout11.his.huawei.com (SkyGuard) with ESMTPS id 4fhW1C64zZz1HBLL; Fri, 27 Mar 2026 01:27:11 +0800 (CST) Received: from mail02.huawei.com (unknown [7.182.16.47]) by mail.maildlp.com (Postfix) with ESMTP id 21EAA4056B; Fri, 27 Mar 2026 01:30:59 +0800 (CST) Received: from huaweicloud.com (unknown [10.204.63.22]) by APP1 (Coremail) with SMTP id LxC2BwB3Yu84bcVppGUvAQ--.1881S4; Thu, 26 Mar 2026 18:30:58 +0100 (CET) From: Roberto Sassu To: corbet@lwn.net, skhan@linuxfoundation.org, zohar@linux.ibm.com, dmitry.kasatkin@gmail.com, eric.snowberg@oracle.com, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, gregorylumen@linux.microsoft.com, chenste@linux.microsoft.com, nramas@linux.microsoft.com, Roberto Sassu Subject: [PATCH v4 02/13] ima: Replace static htable queue with dynamically allocated array Date: Thu, 26 Mar 2026 18:30:00 +0100 Message-ID: <20260326173011.1191815-3-roberto.sassu@huaweicloud.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260326173011.1191815-1-roberto.sassu@huaweicloud.com> References: <20260326173011.1191815-1-roberto.sassu@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: LxC2BwB3Yu84bcVppGUvAQ--.1881S4 X-Coremail-Antispam: 1UD129KBjvJXoW3Xw1fuw45Kr1fCr4rKryxGrg_yoWxWF4Dpa 9rWFyUKr4UAFWxKr97Ja93Kr4fur4vgryUG398G3sYy3W7Ar1IgF1fGFy2vF98ArZ5J3WS qr4jq3Z8AwsYyrJanT9S1TB71UUUUUDqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUPqb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28IrcIa0xkI8VA2jI8067AKxVWUXw A2048vs2IY020Ec7CjxVAFwI0_Xr0E3s1l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0rcxS w2x7M28EF7xvwVC0I7IYx2IY67AKxVW8JVW5JwA2z4x0Y4vE2Ix0cI8IcVCY1x0267AKxV W8Jr0_Cr1UM28EF7xvwVC2z280aVAFwI0_Gr0_Cr1l84ACjcxK6I8E87Iv6xkF7I0E14v2 6r4UJVWxJr1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2 WlYx0E2Ix0cI8IcVAFwI0_Jrv_JF1lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkE bVWUJVW8JwACjcxG0xvY0x0EwIxGrwACI402YVCY1x02628vn2kIc2xKxwCY1x0262kKe7 AKxVWrXVW3AwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02 F40E14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_GFv_Wr ylIxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVW8JVW5JwCI42IY6xIIjxv20xvEc7Cj xVAFwI0_Gr1j6F4UJwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI 0_Gr0_Cr1lIxAIcVC2z280aVCY1x0267AKxVW8Jr0_Cr1UYxBIdaVFxhVjvjDU0xZFpf9x 07jh6pPUUUUU= X-CM-SenderInfo: purev21wro2thvvxqx5xdzvxpfor3voofrz/1tbiAQAEBGnEnSsT2QAAsQ Content-Type: text/plain; charset="utf-8" From: Roberto Sassu The IMA hash table is a fixed-size array of hlist_head buckets: struct hlist_head ima_htable[IMA_MEASURE_HTABLE_SIZE]; IMA_MEASURE_HTABLE_SIZE is (1 << IMA_HASH_BITS) =3D 1024 buckets, each a struct hlist_head (one pointer, 8 bytes on 64-bit). That is 8 KiB allocated in BSS for every kernel, regardless of whether IMA is ever used, and regardless of how many measurements are actually made. Replace the fixed-size array with a RCU-protected pointer to a dynamically allocated array that is initialized in ima_init_htable(), which is called from ima_init() during early boot. ima_init_htable() calls the static function ima_alloc_replace_htable() which, other than initializing the hash table the first time, can also hot-swap the existing hash table with a blank one. The allocation in ima_alloc_replace_htable() uses kcalloc() so the buckets are zero-initialised (equivalent to HLIST_HEAD_INIT { .first =3D NULL }). Callers of ima_alloc_replace_htable() must call synchronize_rcu() and free the returned hash table. Finally, access the hash table with rcu_dereference() in ima_lookup_digest_entry() (reader side) and with rcu_dereference_protected() in ima_add_digest_entry() (writer side). No functional change: bucket count, hash function, and all locking remain identical. Link: https://github.com/linux-integrity/linux/issues/1 Signed-off-by: Roberto Sassu --- security/integrity/ima/ima.h | 3 +- security/integrity/ima/ima_init.c | 5 ++++ security/integrity/ima/ima_queue.c | 48 ++++++++++++++++++++++++++---- 3 files changed, 50 insertions(+), 6 deletions(-) diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index d759988fde45..9cdc4c5afd3b 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -310,6 +310,7 @@ bool ima_template_has_modsig(const struct ima_template_= desc *ima_template); int ima_restore_measurement_entry(struct ima_template_entry *entry); int ima_restore_measurement_list(loff_t bufsize, void *buf); int ima_measurements_show(struct seq_file *m, void *v); +int __init ima_init_htable(void); unsigned long ima_get_binary_runtime_size(void); int ima_init_template(void); void ima_init_template_list(void); @@ -325,7 +326,7 @@ extern spinlock_t ima_queue_lock; =20 extern atomic_long_t ima_num_entries; extern atomic_long_t ima_num_violations; -extern struct hlist_head ima_htable[IMA_MEASURE_HTABLE_SIZE]; +extern struct hlist_head __rcu *ima_htable; =20 static inline unsigned int ima_hash_key(u8 *digest) { diff --git a/security/integrity/ima/ima_init.c b/security/integrity/ima/ima= _init.c index a2f34f2d8ad7..7e0aa09a12e6 100644 --- a/security/integrity/ima/ima_init.c +++ b/security/integrity/ima/ima_init.c @@ -140,6 +140,11 @@ int __init ima_init(void) rc =3D ima_init_digests(); if (rc !=3D 0) return rc; + + rc =3D ima_init_htable(); + if (rc !=3D 0) + return rc; + rc =3D ima_add_boot_aggregate(); /* boot aggregate must be first entry */ if (rc !=3D 0) return rc; diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/im= a_queue.c index 1f6515f7d015..41f4941ceaad 100644 --- a/security/integrity/ima/ima_queue.c +++ b/security/integrity/ima/ima_queue.c @@ -38,9 +38,7 @@ atomic_long_t ima_num_entries =3D ATOMIC_LONG_INIT(0); atomic_long_t ima_num_violations =3D ATOMIC_LONG_INIT(0); =20 /* key: inode (before secure-hashing a file) */ -struct hlist_head ima_htable[IMA_MEASURE_HTABLE_SIZE] =3D { - [0 ... IMA_MEASURE_HTABLE_SIZE - 1] =3D HLIST_HEAD_INIT -}; +struct hlist_head __rcu *ima_htable; =20 /* mutex protects atomicity of extending measurement list * and extending the TPM PCR aggregate. Since tpm_extend can take @@ -54,17 +52,53 @@ static DEFINE_MUTEX(ima_extend_list_mutex); */ static bool ima_measurements_suspended; =20 +/* Callers must call synchronize_rcu() and free the hash table. */ +static struct hlist_head *ima_alloc_replace_htable(void) +{ + struct hlist_head *old_htable, *new_htable; + + /* Initializing to zeros is equivalent to call HLIST_HEAD_INIT. */ + new_htable =3D kcalloc(IMA_MEASURE_HTABLE_SIZE, sizeof(struct hlist_head), + GFP_KERNEL); + if (!new_htable) + return ERR_PTR(-ENOMEM); + + old_htable =3D rcu_replace_pointer(ima_htable, new_htable, + lockdep_is_held(&ima_extend_list_mutex)); + + return old_htable; +} + +int __init ima_init_htable(void) +{ + struct hlist_head *old_htable; + + mutex_lock(&ima_extend_list_mutex); + old_htable =3D ima_alloc_replace_htable(); + mutex_unlock(&ima_extend_list_mutex); + + if (IS_ERR(old_htable)) + return PTR_ERR(old_htable); + + /* Synchronize_rcu() and kfree() not necessary, only for robustness. */ + synchronize_rcu(); + kfree(old_htable); + return 0; +} + /* lookup up the digest value in the hash table, and return the entry */ static struct ima_queue_entry *ima_lookup_digest_entry(u8 *digest_value, int pcr) { struct ima_queue_entry *qe, *ret =3D NULL; + struct hlist_head *htable; unsigned int key; int rc; =20 key =3D ima_hash_key(digest_value); rcu_read_lock(); - hlist_for_each_entry_rcu(qe, &ima_htable[key], hnext) { + htable =3D rcu_dereference(ima_htable); + hlist_for_each_entry_rcu(qe, &htable[key], hnext) { rc =3D memcmp(qe->entry->digests[ima_hash_algo_idx].digest, digest_value, hash_digest_size[ima_hash_algo]); if ((rc =3D=3D 0) && (qe->entry->pcr =3D=3D pcr)) { @@ -104,6 +138,7 @@ static int ima_add_digest_entry(struct ima_template_ent= ry *entry, bool update_htable) { struct ima_queue_entry *qe; + struct hlist_head *htable; unsigned int key; =20 qe =3D kmalloc_obj(*qe); @@ -116,10 +151,13 @@ static int ima_add_digest_entry(struct ima_template_e= ntry *entry, INIT_LIST_HEAD(&qe->later); list_add_tail_rcu(&qe->later, &ima_measurements); 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charset="utf-8" From: Roberto Sassu Make ima_num_entries as an array, to have separate counters per binary measurements list type. Currently, define the BINARY type for the existing binary measurements list. No functional change: the BINARY type is equivalent to the value without the array. Link: https://github.com/linux-integrity/linux/issues/1 Signed-off-by: Roberto Sassu --- security/integrity/ima/ima.h | 9 ++++++++- security/integrity/ima/ima_fs.c | 3 +-- security/integrity/ima/ima_kexec.c | 2 +- security/integrity/ima/ima_queue.c | 7 +++++-- 4 files changed, 15 insertions(+), 6 deletions(-) diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index 9cdc4c5afd3b..199237e2d2e3 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -28,6 +28,13 @@ enum ima_show_type { IMA_SHOW_BINARY, IMA_SHOW_BINARY_NO= _FIELD_LEN, IMA_SHOW_BINARY_OLD_STRING_FMT, IMA_SHOW_ASCII }; enum tpm_pcrs { TPM_PCR0 =3D 0, TPM_PCR8 =3D 8, TPM_PCR10 =3D 10 }; =20 +/* + * BINARY: current binary measurements list + */ +enum binary_lists { + BINARY, BINARY__LAST +}; + /* digest size for IMA, fits SHA1 or MD5 */ #define IMA_DIGEST_SIZE SHA1_DIGEST_SIZE #define IMA_EVENT_NAME_LEN_MAX 255 @@ -324,7 +331,7 @@ int ima_lsm_policy_change(struct notifier_block *nb, un= signed long event, */ extern spinlock_t ima_queue_lock; =20 -extern atomic_long_t ima_num_entries; +extern atomic_long_t ima_num_entries[BINARY__LAST]; extern atomic_long_t ima_num_violations; extern struct hlist_head __rcu *ima_htable; =20 diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_f= s.c index aaa460d70ff7..79b0f287c668 100644 --- a/security/integrity/ima/ima_fs.c +++ b/security/integrity/ima/ima_fs.c @@ -63,8 +63,7 @@ static ssize_t ima_show_measurements_count(struct file *f= ilp, char __user *buf, size_t count, loff_t *ppos) { - return ima_show_counter(buf, count, ppos, &ima_num_entries); - + return ima_show_counter(buf, count, ppos, &ima_num_entries[BINARY]); } =20 static const struct file_operations ima_measurements_count_ops =3D { diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/im= a_kexec.c index 5801649fbbef..40962dc0ca86 100644 --- a/security/integrity/ima/ima_kexec.c +++ b/security/integrity/ima/ima_kexec.c @@ -43,7 +43,7 @@ void ima_measure_kexec_event(const char *event_name) int n; =20 buf_size =3D ima_get_binary_runtime_size(); - len =3D atomic_long_read(&ima_num_entries); + len =3D atomic_long_read(&ima_num_entries[BINARY]); =20 n =3D scnprintf(ima_kexec_event, IMA_KEXEC_EVENT_LEN, "kexec_segment_size=3D%lu;ima_binary_runtime_size=3D%lu;" diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/im= a_queue.c index 41f4941ceaad..952172a4905d 100644 --- a/security/integrity/ima/ima_queue.c +++ b/security/integrity/ima/ima_queue.c @@ -33,7 +33,10 @@ static unsigned long binary_runtime_size =3D ULONG_MAX; #endif =20 /* num of stored measurements in the list */ -atomic_long_t ima_num_entries =3D ATOMIC_LONG_INIT(0); +atomic_long_t ima_num_entries[BINARY__LAST] =3D { + [0 ... 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Currently, define the BINARY type for the existing binary measurements list. Introduce ima_update_binary_runtime_size() to facilitate updating a binary_runtime_size value with a given binary measurement list type. Also add the binary measurements list type parameter to ima_get_binary_runtime_size(), to retrieve the desired value. Retrieving the value is now done under the ima_extend_list_mutex, since there can be concurrent updates. No functional change (except for the mutex usage, that fixes the concurrency issue): the BINARY array element is equivalent to the old binary_runtime_size. Link: https://github.com/linux-integrity/linux/issues/1 Signed-off-by: Roberto Sassu --- security/integrity/ima/ima.h | 2 +- security/integrity/ima/ima_kexec.c | 5 ++-- security/integrity/ima/ima_queue.c | 40 +++++++++++++++++++++--------- 3 files changed, 32 insertions(+), 15 deletions(-) diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index 199237e2d2e3..97b7d6024b5d 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -318,7 +318,7 @@ int ima_restore_measurement_entry(struct ima_template_e= ntry *entry); int ima_restore_measurement_list(loff_t bufsize, void *buf); int ima_measurements_show(struct seq_file *m, void *v); int __init ima_init_htable(void); -unsigned long ima_get_binary_runtime_size(void); +unsigned long ima_get_binary_runtime_size(enum binary_lists binary_list); int ima_init_template(void); void ima_init_template_list(void); int __init ima_init_digests(void); diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/im= a_kexec.c index 40962dc0ca86..44ebefbdcab0 100644 --- a/security/integrity/ima/ima_kexec.c +++ b/security/integrity/ima/ima_kexec.c @@ -42,7 +42,7 @@ void ima_measure_kexec_event(const char *event_name) long len; int n; =20 - buf_size =3D ima_get_binary_runtime_size(); + buf_size =3D ima_get_binary_runtime_size(BINARY); len =3D atomic_long_read(&ima_num_entries[BINARY]); =20 n =3D scnprintf(ima_kexec_event, IMA_KEXEC_EVENT_LEN, @@ -159,7 +159,8 @@ void ima_add_kexec_buffer(struct kimage *image) else extra_memory =3D CONFIG_IMA_KEXEC_EXTRA_MEMORY_KB * 1024; =20 - binary_runtime_size =3D ima_get_binary_runtime_size() + extra_memory; + binary_runtime_size =3D ima_get_binary_runtime_size(BINARY) + + extra_memory; =20 if (binary_runtime_size >=3D ULONG_MAX - PAGE_SIZE) kexec_segment_size =3D ULONG_MAX; diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/im= a_queue.c index 952172a4905d..b6d10dceb669 100644 --- a/security/integrity/ima/ima_queue.c +++ b/security/integrity/ima/ima_queue.c @@ -27,9 +27,11 @@ static struct tpm_digest *digests; =20 LIST_HEAD(ima_measurements); /* list of all measurements */ #ifdef CONFIG_IMA_KEXEC -static unsigned long binary_runtime_size; +static unsigned long binary_runtime_size[BINARY__LAST]; #else -static unsigned long binary_runtime_size =3D ULONG_MAX; +static unsigned long binary_runtime_size[BINARY__LAST] =3D { + [0 ... BINARY__LAST - 1] =3D ULONG_MAX +}; #endif =20 /* num of stored measurements in the list */ @@ -131,6 +133,20 @@ static int get_binary_runtime_size(struct ima_template= _entry *entry) return size; } =20 +static void ima_update_binary_runtime_size(struct ima_template_entry *entr= y, + enum binary_lists binary_list) +{ + int size; + + if (binary_runtime_size[binary_list] =3D=3D ULONG_MAX) + return; + + size =3D get_binary_runtime_size(entry); + binary_runtime_size[binary_list] =3D + (binary_runtime_size[binary_list] < ULONG_MAX - size) ? + binary_runtime_size[binary_list] + size : ULONG_MAX; +} + /* ima_add_template_entry helper function: * - Add template entry to the measurement list and hash table, for * all entries except those carried across kexec. @@ -163,13 +179,7 @@ static int ima_add_digest_entry(struct ima_template_en= try *entry, hlist_add_head_rcu(&qe->hnext, &htable[key]); } =20 - if (binary_runtime_size !=3D ULONG_MAX) { - int size; - - size =3D get_binary_runtime_size(entry); 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dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.18.224.235]) by frasgout11.his.huawei.com (SkyGuard) with ESMTPS id 4fhW1h5Kqdz1HBts; Fri, 27 Mar 2026 01:27:36 +0800 (CST) Received: from mail02.huawei.com (unknown [7.182.16.47]) by mail.maildlp.com (Postfix) with ESMTP id 07B9340560; Fri, 27 Mar 2026 01:31:24 +0800 (CST) Received: from huaweicloud.com (unknown [10.204.63.22]) by APP1 (Coremail) with SMTP id LxC2BwB3Yu84bcVppGUvAQ--.1881S7; Thu, 26 Mar 2026 18:31:23 +0100 (CET) From: Roberto Sassu To: corbet@lwn.net, skhan@linuxfoundation.org, zohar@linux.ibm.com, dmitry.kasatkin@gmail.com, eric.snowberg@oracle.com, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, gregorylumen@linux.microsoft.com, chenste@linux.microsoft.com, nramas@linux.microsoft.com, Roberto Sassu Subject: [PATCH v4 05/13] ima: Introduce _ima_measurements_start() and _ima_measurements_next() Date: Thu, 26 Mar 2026 18:30:03 +0100 Message-ID: <20260326173011.1191815-6-roberto.sassu@huaweicloud.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260326173011.1191815-1-roberto.sassu@huaweicloud.com> References: <20260326173011.1191815-1-roberto.sassu@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: LxC2BwB3Yu84bcVppGUvAQ--.1881S7 X-Coremail-Antispam: 1UD129KBjvJXoW7Kry8Jw4fAryrGFWxZw1xGrg_yoW5JFyxpa sxua4rCF4kJ3yxWF1xGrWDWr4ru3sag3WDWrWUJ34vvF1UJr1v9r43Aw12vrn0y348Xr1v vr90gr45Cw4FyaDanT9S1TB71UUUUUDqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUPlb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28IrcIa0xkI8VA2jI8067AKxVWUAV Cq3wA2048vs2IY020Ec7CjxVAFwI0_Xr0E3s1l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0 rcxSw2x7M28EF7xvwVC0I7IYx2IY67AKxVW8JVW5JwA2z4x0Y4vE2Ix0cI8IcVCY1x0267 AKxVW8Jr0_Cr1UM28EF7xvwVC2z280aVAFwI0_Gr0_Cr1l84ACjcxK6I8E87Iv6xkF7I0E 14v26r4UJVWxJr1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrV C2j2WlYx0E2Ix0cI8IcVAFwI0_Jrv_JF1lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE 7xkEbVWUJVW8JwACjcxG0xvY0x0EwIxGrwACI402YVCY1x02628vn2kIc2xKxwCY1x0262 kKe7AKxVWrXVW3AwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s02 6c02F40E14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_GF v_WrylIxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVW8JVW5JwCI42IY6xIIjxv20xvE c7CjxVAFwI0_Gr1j6F4UJwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aV AFwI0_Gr0_Cr1lIxAIcVC2z280aVCY1x0267AKxVW8Jr0_Cr1UYxBIdaVFxhVjvjDU0xZF pf9x07jhXo7UUUUU= X-CM-SenderInfo: purev21wro2thvvxqx5xdzvxpfor3voofrz/1tbiAgAEBGnEnS4T6AAAsn Content-Type: text/plain; charset="utf-8" From: Roberto Sassu Introduce _ima_measurements_start() and _ima_measurements_next(), renamed from ima_measurements_start() and ima_measurements_next(), to include the list head as an additional parameter, so that iteration on different lists can be implemented by calling those functions. No functional change: ima_measurements_start() and ima_measurements_next() pass the ima_measurements list head, used before. Link: https://github.com/linux-integrity/linux/issues/1 Signed-off-by: Roberto Sassu --- security/integrity/ima/ima_fs.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_f= s.c index 79b0f287c668..9a8dba14d82a 100644 --- a/security/integrity/ima/ima_fs.c +++ b/security/integrity/ima/ima_fs.c @@ -72,14 +72,15 @@ static const struct file_operations ima_measurements_co= unt_ops =3D { }; =20 /* returns pointer to hlist_node */ -static void *ima_measurements_start(struct seq_file *m, loff_t *pos) +static void *_ima_measurements_start(struct seq_file *m, loff_t *pos, + struct list_head *head) { loff_t l =3D *pos; struct ima_queue_entry *qe; =20 /* we need a lock since pos could point beyond last element */ rcu_read_lock(); - list_for_each_entry_rcu(qe, &ima_measurements, later) { + list_for_each_entry_rcu(qe, head, later) { if (!l--) { rcu_read_unlock(); return qe; @@ -89,7 +90,13 @@ static void *ima_measurements_start(struct seq_file *m, = loff_t *pos) return NULL; } =20 -static void *ima_measurements_next(struct seq_file *m, void *v, loff_t *po= s) +static void *ima_measurements_start(struct seq_file *m, loff_t *pos) +{ + return _ima_measurements_start(m, pos, &ima_measurements); +} + +static void *_ima_measurements_next(struct seq_file *m, void *v, loff_t *p= os, + struct list_head *head) { struct ima_queue_entry *qe =3D v; =20 @@ -101,7 +108,12 @@ static void *ima_measurements_next(struct seq_file *m,= void *v, loff_t *pos) rcu_read_unlock(); (*pos)++; =20 - return (&qe->later =3D=3D &ima_measurements) ? NULL : qe; + return (&qe->later =3D=3D head) ? NULL : qe; +} + +static void *ima_measurements_next(struct seq_file *m, void *v, loff_t *po= s) +{ + return _ima_measurements_next(m, v, pos, &ima_measurements); } =20 static void ima_measurements_stop(struct seq_file *m, void *v) --=20 2.43.0 From nobody Thu Apr 2 18:49:56 2026 Received: from frasgout13.his.huawei.com (frasgout13.his.huawei.com [14.137.139.46]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 108CD4279E0; Thu, 26 Mar 2026 17:31:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=14.137.139.46 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774546302; cv=none; b=rwUJcANyb3Ozym8zUfi+yIWvzclK6rbaJ4WipHvI76YsVa8muveksQY3OR4m/7eBS12OJaLh7cY3j3/ttq4QgpLA+4U7sxngNlEpE5dCEFdgTwusA2IYDP3dbrXOuOyudTj6gZxWK6NpfeiSxye9FpQ9bAkgXOCnJHZTeaqQ87s= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774546302; c=relaxed/simple; bh=EOZOjyjMg6/Fn5W/fcIBelXq1e2DV8pmyX8Hk++1dSw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Ez6q+D6smHXCF1lZSkXsaDoKN72uabTftxVMB0ZQn75aC0qDqgemin5IJSxVjhWT8Vs5uFxtop68V86W64BIddMAIzTGJqcEMzFCKhlNXN4H8yvtfEbzdVU/vuvSjKtMRZJaQwmTdXQhgcOvVU1YiIL/ZPB75dRuzMqBVd8DKU4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=14.137.139.46 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.18.224.235]) by frasgout13.his.huawei.com (SkyGuard) with ESMTPS id 4fhW1r0TMkzpVh5; Fri, 27 Mar 2026 01:27:44 +0800 (CST) Received: from mail02.huawei.com (unknown [7.182.16.47]) by mail.maildlp.com (Postfix) with ESMTP id 4DCE840560; Fri, 27 Mar 2026 01:31:32 +0800 (CST) Received: from huaweicloud.com (unknown [10.204.63.22]) by APP1 (Coremail) with SMTP id LxC2BwB3Yu84bcVppGUvAQ--.1881S8; Thu, 26 Mar 2026 18:31:31 +0100 (CET) From: Roberto Sassu To: corbet@lwn.net, skhan@linuxfoundation.org, zohar@linux.ibm.com, dmitry.kasatkin@gmail.com, eric.snowberg@oracle.com, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, gregorylumen@linux.microsoft.com, chenste@linux.microsoft.com, nramas@linux.microsoft.com, Roberto Sassu Subject: [PATCH v4 06/13] ima: Mediate open/release method of the measurements list Date: Thu, 26 Mar 2026 18:30:04 +0100 Message-ID: <20260326173011.1191815-7-roberto.sassu@huaweicloud.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260326173011.1191815-1-roberto.sassu@huaweicloud.com> References: <20260326173011.1191815-1-roberto.sassu@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: LxC2BwB3Yu84bcVppGUvAQ--.1881S8 X-Coremail-Antispam: 1UD129KBjvJXoWxur1kCFW7ZFy5CFyDJryUAwb_yoWrCr43pa 93C3yrCr1kJrWfWFn7Ga47Zr4F9a4rKa15Wr4DJa4fAF1rJr9F9F4Yyr12kFs8tryrGr18 Xw4qqr45uas0yaDanT9S1TB71UUUUUDqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUPlb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28IrcIa0xkI8VA2jI8067AKxVWUAV Cq3wA2048vs2IY020Ec7CjxVAFwI0_Xr0E3s1l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0 rcxSw2x7M28EF7xvwVC0I7IYx2IY67AKxVW5JVW7JwA2z4x0Y4vE2Ix0cI8IcVCY1x0267 AKxVW8Jr0_Cr1UM28EF7xvwVC2z280aVAFwI0_Gr0_Cr1l84ACjcxK6I8E87Iv6xkF7I0E 14v26r4UJVWxJr1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrV C2j2WlYx0E2Ix0cI8IcVAFwI0_Jrv_JF1lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE 7xkEbVWUJVW8JwACjcxG0xvY0x0EwIxGrwACI402YVCY1x02628vn2kIc2xKxwCY1x0262 kKe7AKxVWrXVW3AwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s02 6c02F40E14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_GF v_WrylIxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVW5JVW7JwCI42IY6xIIjxv20xvE c7CjxVAFwI0_Gr1j6F4UJwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aV AFwI0_Gr0_Cr1lIxAIcVC2z280aVCY1x0267AKxVW8Jr0_Cr1UYxBIdaVFxhVjvjDU0xZF pf9x07jhXo7UUUUU= X-CM-SenderInfo: purev21wro2thvvxqx5xdzvxpfor3voofrz/1tbiAQAEBGnEnSsT2wAAsS Content-Type: text/plain; charset="utf-8" From: Roberto Sassu Introduce the ima_measure_users counter, to implement a semaphore-like locking scheme where the binary and ASCII measurements list interfaces can be concurrently open by multiple readers, or alternatively by a single writer. A semaphore cannot be used because the kernel cannot return to user space with a lock held. Introduce the ima_measure_lock() and ima_measure_unlock() primitives, to respectively lock/unlock the interfaces (safely with the ima_measure_users counter, without holding a lock). Finally, introduce _ima_measurements_open() to lock the interface before seq_open(), and call it from ima_measurements_open() and ima_ascii_measurements_open(). And, introduce ima_measurements_release(), to unlock the interface. Require CAP_SYS_ADMIN if the interface is opened for write (not possible for the current measurements interfaces, since they only have read permission). No functional changes: multiple readers are allowed as before. Link: https://github.com/linux-integrity/linux/issues/1 Signed-off-by: Roberto Sassu --- security/integrity/ima/ima_fs.c | 71 +++++++++++++++++++++++++++++++-- 1 file changed, 67 insertions(+), 4 deletions(-) diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_f= s.c index 9a8dba14d82a..68edea7139d5 100644 --- a/security/integrity/ima/ima_fs.c +++ b/security/integrity/ima/ima_fs.c @@ -25,6 +25,8 @@ #include "ima.h" =20 static DEFINE_MUTEX(ima_write_mutex); +static DEFINE_MUTEX(ima_measure_mutex); +static long ima_measure_users; =20 bool ima_canonical_fmt; static int __init default_canonical_fmt_setup(char *str) @@ -209,16 +211,76 @@ static const struct seq_operations ima_measurments_se= qops =3D { .show =3D ima_measurements_show }; =20 +static int ima_measure_lock(bool write) +{ + mutex_lock(&ima_measure_mutex); + if ((write && ima_measure_users !=3D 0) || + (!write && ima_measure_users < 0)) { + mutex_unlock(&ima_measure_mutex); + return -EBUSY; + } + + if (write) + ima_measure_users--; + else + ima_measure_users++; + mutex_unlock(&ima_measure_mutex); + return 0; +} + +static void ima_measure_unlock(bool write) +{ + mutex_lock(&ima_measure_mutex); + if (write) + ima_measure_users++; + else + ima_measure_users--; + mutex_unlock(&ima_measure_mutex); +} + +static int _ima_measurements_open(struct inode *inode, struct file *file, + const struct seq_operations *seq_ops) +{ + bool write =3D (file->f_mode & FMODE_WRITE); + int ret; + + if (write && !capable(CAP_SYS_ADMIN)) + return -EPERM; + + ret =3D ima_measure_lock(write); + if (ret < 0) + return ret; + + ret =3D seq_open(file, seq_ops); + if (ret < 0) + ima_measure_unlock(write); + + return ret; +} + static int ima_measurements_open(struct inode *inode, struct file *file) { - return seq_open(file, &ima_measurments_seqops); + return _ima_measurements_open(inode, file, &ima_measurments_seqops); +} + +static int ima_measurements_release(struct inode *inode, struct file *file) +{ + bool write =3D (file->f_mode & FMODE_WRITE); + int ret; + + /* seq_release() always returns zero. */ + ret =3D seq_release(inode, file); + + ima_measure_unlock(write); + + return ret; } =20 static const struct file_operations ima_measurements_ops =3D { .open =3D ima_measurements_open, .read =3D seq_read, .llseek =3D seq_lseek, - .release =3D seq_release, + .release =3D ima_measurements_release, }; =20 void ima_print_digest(struct seq_file *m, u8 *digest, u32 size) @@ -283,14 +345,15 @@ static const struct seq_operations ima_ascii_measurem= ents_seqops =3D { =20 static int ima_ascii_measurements_open(struct inode *inode, struct file *f= ile) { - return seq_open(file, &ima_ascii_measurements_seqops); + return _ima_measurements_open(inode, file, + &ima_ascii_measurements_seqops); } =20 static const struct file_operations ima_ascii_measurements_ops =3D { .open =3D ima_ascii_measurements_open, .read =3D seq_read, .llseek =3D seq_lseek, - .release =3D seq_release, + .release =3D ima_measurements_release, }; =20 static ssize_t ima_read_policy(char *path) --=20 2.43.0 From nobody Thu Apr 2 18:49:56 2026 Received: from frasgout13.his.huawei.com (frasgout13.his.huawei.com [14.137.139.46]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 51D1C428473; 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dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.18.224.235]) by frasgout13.his.huawei.com (SkyGuard) with ESMTPS id 4fhW202NKkzpW04; Fri, 27 Mar 2026 01:27:52 +0800 (CST) Received: from mail02.huawei.com (unknown [7.182.16.47]) by mail.maildlp.com (Postfix) with ESMTP id 8F18A40560; Fri, 27 Mar 2026 01:31:40 +0800 (CST) Received: from huaweicloud.com (unknown [10.204.63.22]) by APP1 (Coremail) with SMTP id LxC2BwB3Yu84bcVppGUvAQ--.1881S9; Thu, 26 Mar 2026 18:31:40 +0100 (CET) From: Roberto Sassu To: corbet@lwn.net, skhan@linuxfoundation.org, zohar@linux.ibm.com, dmitry.kasatkin@gmail.com, eric.snowberg@oracle.com, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, gregorylumen@linux.microsoft.com, chenste@linux.microsoft.com, nramas@linux.microsoft.com, Roberto Sassu Subject: [PATCH v4 07/13] ima: Use snprintf() in create_securityfs_measurement_lists Date: Thu, 26 Mar 2026 18:30:05 +0100 Message-ID: <20260326173011.1191815-8-roberto.sassu@huaweicloud.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260326173011.1191815-1-roberto.sassu@huaweicloud.com> References: <20260326173011.1191815-1-roberto.sassu@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: LxC2BwB3Yu84bcVppGUvAQ--.1881S9 X-Coremail-Antispam: 1UD129KBjvJXoW7tFy5XFWDWw1rtF1kWr4rXwb_yoW8tF48pa ySgF18Crs5J3yxKFn3K3Z7uaySk3yagF1UW3yvg3WkAFn3XrWFkr4vkr1jkr95Kr10yFy8 XrsFqF13C3Z0yaDanT9S1TB71UUUUUDqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUPlb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28IrcIa0xkI8VA2jI8067AKxVWUAV Cq3wA2048vs2IY020Ec7CjxVAFwI0_Xr0E3s1l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0 rcxSw2x7M28EF7xvwVC0I7IYx2IY67AKxVW5JVW7JwA2z4x0Y4vE2Ix0cI8IcVCY1x0267 AKxVW8Jr0_Cr1UM28EF7xvwVC2z280aVAFwI0_Gr0_Cr1l84ACjcxK6I8E87Iv6xkF7I0E 14v26r4UJVWxJr1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrV C2j2WlYx0E2Ix0cI8IcVAFwI0_Jrv_JF1lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE 7xkEbVWUJVW8JwACjcxG0xvY0x0EwIxGrwACI402YVCY1x02628vn2kIc2xKxwCY1x0262 kKe7AKxVWrXVW3AwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s02 6c02F40E14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_GF v_WrylIxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVW5JVW7JwCI42IY6xIIjxv20xvE c7CjxVAFwI0_Gr1j6F4UJwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aV AFwI0_Gr0_Cr1lIxAIcVC2z280aVCY1x0267AKxVW8Jr0_Cr1UYxBIdaVFxhVjvjDU0xZF pf9x07jhXo7UUUUU= X-CM-SenderInfo: purev21wro2thvvxqx5xdzvxpfor3voofrz/1tbiAgAEBGnEnS4T6QAAsm Content-Type: text/plain; charset="utf-8" From: Roberto Sassu Use the more secure snprintf() function (accepting the buffer size) in create_securityfs_measurement_lists(). No functional change: sprintf() and snprintf() have the same behavior. Link: https://github.com/linux-integrity/linux/issues/1 Signed-off-by: Roberto Sassu --- security/integrity/ima/ima_fs.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_f= s.c index 68edea7139d5..7709a4576322 100644 --- a/security/integrity/ima/ima_fs.c +++ b/security/integrity/ima/ima_fs.c @@ -472,11 +472,13 @@ static int __init create_securityfs_measurement_lists= (void) struct dentry *dentry; =20 if (algo =3D=3D HASH_ALGO__LAST) - sprintf(file_name, "ascii_runtime_measurements_tpm_alg_%x", - ima_tpm_chip->allocated_banks[i].alg_id); + snprintf(file_name, sizeof(file_name), + "ascii_runtime_measurements_tpm_alg_%x", + ima_tpm_chip->allocated_banks[i].alg_id); else - sprintf(file_name, "ascii_runtime_measurements_%s", - hash_algo_name[algo]); + snprintf(file_name, sizeof(file_name), + "ascii_runtime_measurements_%s", + hash_algo_name[algo]); dentry =3D securityfs_create_file(file_name, S_IRUSR | S_IRGRP, ima_dir, (void *)(uintptr_t)i, &ima_ascii_measurements_ops); @@ -484,11 +486,13 @@ static int __init create_securityfs_measurement_lists= (void) return PTR_ERR(dentry); =20 if (algo =3D=3D HASH_ALGO__LAST) - sprintf(file_name, "binary_runtime_measurements_tpm_alg_%x", - ima_tpm_chip->allocated_banks[i].alg_id); + snprintf(file_name, sizeof(file_name), + "binary_runtime_measurements_tpm_alg_%x", + ima_tpm_chip->allocated_banks[i].alg_id); else - sprintf(file_name, "binary_runtime_measurements_%s", - hash_algo_name[algo]); + snprintf(file_name, sizeof(file_name), + "binary_runtime_measurements_%s", + hash_algo_name[algo]); dentry =3D securityfs_create_file(file_name, S_IRUSR | S_IRGRP, ima_dir, (void *)(uintptr_t)i, &ima_measurements_ops); --=20 2.43.0 From nobody Thu Apr 2 18:49:56 2026 Received: from frasgout12.his.huawei.com (frasgout12.his.huawei.com [14.137.139.154]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9179D426ED4; Thu, 26 Mar 2026 17:31:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; 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spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.18.224.235]) by frasgout12.his.huawei.com (SkyGuard) with ESMTPS id 4fhW2N34KMztKR0; Fri, 27 Mar 2026 01:28:12 +0800 (CST) Received: from mail02.huawei.com (unknown [7.182.16.47]) by mail.maildlp.com (Postfix) with ESMTP id D571940569; Fri, 27 Mar 2026 01:31:48 +0800 (CST) Received: from huaweicloud.com (unknown [10.204.63.22]) by APP1 (Coremail) with SMTP id LxC2BwB3Yu84bcVppGUvAQ--.1881S10; Thu, 26 Mar 2026 18:31:48 +0100 (CET) From: Roberto Sassu To: corbet@lwn.net, skhan@linuxfoundation.org, zohar@linux.ibm.com, dmitry.kasatkin@gmail.com, eric.snowberg@oracle.com, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, gregorylumen@linux.microsoft.com, chenste@linux.microsoft.com, nramas@linux.microsoft.com, Roberto Sassu Subject: [PATCH v4 08/13] ima: Introduce ima_dump_measurement() Date: Thu, 26 Mar 2026 18:30:06 +0100 Message-ID: <20260326173011.1191815-9-roberto.sassu@huaweicloud.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260326173011.1191815-1-roberto.sassu@huaweicloud.com> References: <20260326173011.1191815-1-roberto.sassu@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: LxC2BwB3Yu84bcVppGUvAQ--.1881S10 X-Coremail-Antispam: 1UD129KBjvJXoW7CFyfXryDAw1rKFyfCFy7trb_yoW8AF43pa 9IgFy8Cr18tFyxKrn3GF98Ja1F93y8AF1UW3yDWwn3XF1DJr1Dur95Cr1IvrZ8GrZayF1x tw4agF4ruan0yaDanT9S1TB71UUUUUDqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUPlb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28IrcIa0xkI8VA2jI8067AKxVWUAV Cq3wA2048vs2IY020Ec7CjxVAFwI0_Xr0E3s1l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0 rcxSw2x7M28EF7xvwVC0I7IYx2IY67AKxVW5JVW7JwA2z4x0Y4vE2Ix0cI8IcVCY1x0267 AKxVW8Jr0_Cr1UM28EF7xvwVC2z280aVAFwI0_Gr0_Cr1l84ACjcxK6I8E87Iv6xkF7I0E 14v26r4UJVWxJr1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrV C2j2WlYx0E2Ix0cI8IcVAFwI0_Jrv_JF1lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE 7xkEbVWUJVW8JwACjcxG0xvY0x0EwIxGrwACI402YVCY1x02628vn2kIc2xKxwCY1x0262 kKe7AKxVWrXVW3AwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s02 6c02F40E14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_GF v_WrylIxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVW5JVW7JwCI42IY6xIIjxv20xvE c7CjxVAFwI0_Gr1j6F4UJwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aV AFwI0_Gr0_Cr1lIxAIcVC2z280aVCY1x0267AKxVW8Jr0_Cr1UYxBIdaVFxhVjvjDU0xZF pf9x07jhXo7UUUUU= X-CM-SenderInfo: purev21wro2thvvxqx5xdzvxpfor3voofrz/1tbiAgAEBGnEnS4T6QABsn Content-Type: text/plain; charset="utf-8" From: Roberto Sassu Introduce ima_dump_measurement() to simplify the code of ima_dump_measurement_list() and to avoid repeating the ima_dump_measurement() code block if iteration occurs on multiple lists. No functional change: only code moved to a separate function. Link: https://github.com/linux-integrity/linux/issues/1 Signed-off-by: Roberto Sassu --- security/integrity/ima/ima_kexec.c | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-) diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/im= a_kexec.c index 44ebefbdcab0..d7d0fb639d99 100644 --- a/security/integrity/ima/ima_kexec.c +++ b/security/integrity/ima/ima_kexec.c @@ -80,6 +80,17 @@ static int ima_alloc_kexec_file_buf(size_t segment_size) return 0; } =20 +static int ima_dump_measurement(struct ima_kexec_hdr *khdr, + struct ima_queue_entry *qe) +{ + if (ima_kexec_file.count >=3D ima_kexec_file.size) + return -EINVAL; + + khdr->count++; + ima_measurements_show(&ima_kexec_file, qe); + return 0; +} + static int ima_dump_measurement_list(unsigned long *buffer_size, void **bu= ffer, unsigned long segment_size) { @@ -97,13 +108,9 @@ static int ima_dump_measurement_list(unsigned long *buf= fer_size, void **buffer, khdr.version =3D 1; /* This is an append-only list, no need to hold the RCU read lock */ list_for_each_entry_rcu(qe, &ima_measurements, later, true) { - if (ima_kexec_file.count < ima_kexec_file.size) { - khdr.count++; - ima_measurements_show(&ima_kexec_file, qe); - } else { - ret =3D -EINVAL; + ret =3D ima_dump_measurement(&khdr, qe); + if (ret < 0) break; - } } =20 /* --=20 2.43.0 From nobody Thu Apr 2 18:49:56 2026 Received: from frasgout11.his.huawei.com (frasgout11.his.huawei.com [14.137.139.23]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9116C40148F; Thu, 26 Mar 2026 17:31:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=14.137.139.23 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774546326; cv=none; b=A+/lgpCCNRge1KB8wcdGd+ESjaTkHuueR31Gmq6w0EfYq5JFepWqQIFp5mxNy9QbWkb0k3aj8Gb+03E0OtEue2wNwhrhoB+jgCNql9za6BD10tj1nZIJougv36uzL1JZueTgQ3Jx6CagDYUZSwKrYsBXRcAnhzon0YdlrSdIDqE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774546326; c=relaxed/simple; bh=9p7fWaVl7ZEWmOdGITQtOUzcTdTRbGufiwagrCQXlbo=; 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Thu, 26 Mar 2026 18:31:56 +0100 (CET) From: Roberto Sassu To: corbet@lwn.net, skhan@linuxfoundation.org, zohar@linux.ibm.com, dmitry.kasatkin@gmail.com, eric.snowberg@oracle.com, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, gregorylumen@linux.microsoft.com, chenste@linux.microsoft.com, nramas@linux.microsoft.com, Roberto Sassu Subject: [PATCH v4 09/13] ima: Add support for staging measurements with prompt Date: Thu, 26 Mar 2026 18:30:07 +0100 Message-ID: <20260326173011.1191815-10-roberto.sassu@huaweicloud.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260326173011.1191815-1-roberto.sassu@huaweicloud.com> References: <20260326173011.1191815-1-roberto.sassu@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: LxC2BwB3Yu84bcVppGUvAQ--.1881S11 X-Coremail-Antispam: 1UD129KBjvAXoW3tw18Cr1DKFW5AF48Zw4kXrb_yoW8CFykWo Za9rZ8GF48Wrn3Cw4UKrsxtFy8WFZ5Wws7Jr4rtrs8CF129r15GayIq3WUAa1Iqw4rW34U G34kA348ZFs2q3Z3n29KB7ZKAUJUUUU5529EdanIXcx71UUUUU7v73VFW2AGmfu7bjvjm3 AaLaJ3UjIYCTnIWjp_UUUOo7kC6x804xWl14x267AKxVWrJVCq3wAFc2x0x2IEx4CE42xK 8VAvwI8IcIk0rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_JF 0E3s1l82xGYIkIc2x26xkF7I0E14v26ryj6s0DM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vE j48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Xr0_Ar1l84ACjcxK6xIIjxv20xvEc7CjxV AFwI0_Gr1j6F4UJwA2z4x0Y4vEx4A2jsIE14v26r4j6F4UM28EF7xvwVC2z280aVCY1x02 67AKxVW8Jr0_Cr1UM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F4 0Ex7xfMcIj6xIIjxv20xvE14v26r1Y6r17McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC 6x0Yz7v_Jr0_Gr1lF7xvr2IYc2Ij64vIr41lFIxGxcIEc7CjxVA2Y2ka0xkIwI1lc7CjxV Aaw2AFwI0_Wrv_ZF1l42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2Iq xVAqx4xG67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r 4a6rW5MIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Xr0_Ar1lIxAIcVC0I7IYx2IY 6xkF7I0E14v26r4UJVWxJr1lIxAIcVCF04k26cxKx2IYs7xG6r1j6r1xMIIF0xvEx4A2js IE14v26r4j6F4UMIIF0xvEx4A2jsIEc7CjxVAFwI0_Gr1j6F4UJbIYCTnIWIevJa73UjIF yTuYvjxUVdgAUUUUU X-CM-SenderInfo: purev21wro2thvvxqx5xdzvxpfor3voofrz/1tbiAQAEBGnEnSsT3gAAsX Content-Type: text/plain; charset="utf-8" From: Roberto Sassu Introduce the ability of staging the IMA measurement list and deleting them with a prompt. Staging means moving the current content of the measurement list to a separate location, and allowing users to read and delete it. This causes the measurement list to be atomically truncated before new measurements can be added. Staging can be done only once at a time. In the event of kexec(), staging is reverted and staged entries will be carried over to the new kernel. Introduce ascii_runtime_measurements__staged and binary_runtime_measurements__staged interfaces to stage and delete the measurements. Use 'echo A > ' and 'echo D > ' to respectively stage and delete the entire measurements list. Locking of these interfaces is also mediated with a call to _ima_measurements_open() and with ima_measurements_release(). Implement the staging functionality by introducing the new global measurements list ima_measurements_staged, and ima_queue_stage() and ima_queue_delete_staged_all() to respectively move measurements from the current measurements list to the staged one, and to move staged measurements to the ima_measurements_trim list for deletion. Introduce ima_queue_delete() to delete the measurements. Finally, introduce the BINARY_STAGED AND BINARY_FULL binary measurements list types, to maintain the counters and the binary size of staged measurements and the full measurements list (including entries that were staged). BINARY still represents the current binary measurements list. Use the binary size for the BINARY + BINARY_STAGED types in ima_add_kexec_buffer(), since both measurements list types are copied to the secondary kernel during kexec. Use BINARY_FULL in ima_measure_kexec_event(), to generate a critical data record. It should be noted that the BINARY_FULL counter is not passed through kexec. Thus, the number of entries included in the kexec critical data records refers to the entries since the previous kexec records. Note: This code derives from the Alt-IMA Huawei project, whose license is GPL-2.0 OR MIT. Link: https://github.com/linux-integrity/linux/issues/1 Suggested-by: Gregory Lumen (staging rev= ert) Signed-off-by: Roberto Sassu --- security/integrity/ima/Kconfig | 13 +++ security/integrity/ima/ima.h | 8 +- security/integrity/ima/ima_fs.c | 167 ++++++++++++++++++++++++++--- security/integrity/ima/ima_kexec.c | 22 +++- security/integrity/ima/ima_queue.c | 97 ++++++++++++++++- 5 files changed, 286 insertions(+), 21 deletions(-) diff --git a/security/integrity/ima/Kconfig b/security/integrity/ima/Kconfig index 976e75f9b9ba..e714726f3384 100644 --- a/security/integrity/ima/Kconfig +++ b/security/integrity/ima/Kconfig @@ -332,4 +332,17 @@ config IMA_KEXEC_EXTRA_MEMORY_KB If set to the default value of 0, an extra half page of memory for those additional measurements will be allocated. =20 +config IMA_STAGING + bool "Support for staging the measurements list" + default y + help + Add support for staging the measurements list. + + It allows user space to stage the measurements list for deletion and + to delete the staged measurements after confirmation. + + On kexec, staging is reverted and staged measurements are prepended + to the current measurements list when measurements are copied to the + secondary kernel. + endif diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index 97b7d6024b5d..65db152a0a24 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -30,9 +30,11 @@ enum tpm_pcrs { TPM_PCR0 =3D 0, TPM_PCR8 =3D 8, TPM_PCR1= 0 =3D 10 }; =20 /* * BINARY: current binary measurements list + * BINARY_STAGED: staged binary measurements list + * BINARY_FULL: binary measurements list since IMA init (lost after kexec) */ enum binary_lists { - BINARY, BINARY__LAST + BINARY, BINARY_STAGED, BINARY_FULL, BINARY__LAST }; =20 /* digest size for IMA, fits SHA1 or MD5 */ @@ -125,6 +127,7 @@ struct ima_queue_entry { struct ima_template_entry *entry; }; extern struct list_head ima_measurements; /* list of all measurements */ +extern struct list_head ima_measurements_staged; /* list of staged meas. */ =20 /* Some details preceding the binary serialized measurement list */ struct ima_kexec_hdr { @@ -314,6 +317,8 @@ struct ima_template_desc *ima_template_desc_current(voi= d); struct ima_template_desc *ima_template_desc_buf(void); struct ima_template_desc *lookup_template_desc(const char *name); bool ima_template_has_modsig(const struct ima_template_desc *ima_template); +int ima_queue_stage(void); +int ima_queue_staged_delete_all(void); int ima_restore_measurement_entry(struct ima_template_entry *entry); int ima_restore_measurement_list(loff_t bufsize, void *buf); int ima_measurements_show(struct seq_file *m, void *v); @@ -334,6 +339,7 @@ extern spinlock_t ima_queue_lock; extern atomic_long_t ima_num_entries[BINARY__LAST]; extern atomic_long_t ima_num_violations; extern struct hlist_head __rcu *ima_htable; +extern struct mutex ima_extend_list_mutex; =20 static inline unsigned int ima_hash_key(u8 *digest) { diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_f= s.c index 7709a4576322..39d9128e9f22 100644 --- a/security/integrity/ima/ima_fs.c +++ b/security/integrity/ima/ima_fs.c @@ -24,6 +24,13 @@ =20 #include "ima.h" =20 +/* + * Requests: + * 'A\n': stage the entire measurements list + * 'D\n': delete all staged measurements + */ +#define STAGED_REQ_LENGTH 21 + static DEFINE_MUTEX(ima_write_mutex); static DEFINE_MUTEX(ima_measure_mutex); static long ima_measure_users; @@ -97,6 +104,11 @@ static void *ima_measurements_start(struct seq_file *m,= loff_t *pos) return _ima_measurements_start(m, pos, &ima_measurements); } =20 +static void *ima_measurements_staged_start(struct seq_file *m, loff_t *pos) +{ + return _ima_measurements_start(m, pos, &ima_measurements_staged); +} + static void *_ima_measurements_next(struct seq_file *m, void *v, loff_t *p= os, struct list_head *head) { @@ -118,6 +130,12 @@ static void *ima_measurements_next(struct seq_file *m,= void *v, loff_t *pos) return _ima_measurements_next(m, v, pos, &ima_measurements); } =20 +static void *ima_measurements_staged_next(struct seq_file *m, void *v, + loff_t *pos) +{ + return _ima_measurements_next(m, v, pos, &ima_measurements_staged); +} + static void ima_measurements_stop(struct seq_file *m, void *v) { } @@ -283,6 +301,68 @@ static const struct file_operations ima_measurements_o= ps =3D { .release =3D ima_measurements_release, }; =20 +static const struct seq_operations ima_measurments_staged_seqops =3D { + .start =3D ima_measurements_staged_start, + .next =3D ima_measurements_staged_next, + .stop =3D ima_measurements_stop, + .show =3D ima_measurements_show +}; + +static int ima_measurements_staged_open(struct inode *inode, struct file *= file) +{ + return _ima_measurements_open(inode, file, + &ima_measurments_staged_seqops); +} + +static ssize_t ima_measurements_staged_write(struct file *file, + const char __user *buf, + size_t datalen, loff_t *ppos) +{ + char req[STAGED_REQ_LENGTH]; + int ret; + + if (*ppos > 0 || datalen < 2 || datalen > STAGED_REQ_LENGTH) + return -EINVAL; + + if (copy_from_user(req, buf, datalen) !=3D 0) + return -EFAULT; + + if (req[datalen - 1] !=3D '\n') + return -EINVAL; + + req[datalen - 1] =3D '\0'; + + switch (req[0]) { + case 'A': + if (datalen !=3D 2) + return -EINVAL; + + ret =3D ima_queue_stage(); + break; + case 'D': + if (datalen !=3D 2) + return -EINVAL; + + ret =3D ima_queue_staged_delete_all(); + break; + default: + ret =3D -EINVAL; + } + + if (ret < 0) + return ret; + + return datalen; +} + +static const struct file_operations ima_measurements_staged_ops =3D { + .open =3D ima_measurements_staged_open, + .read =3D seq_read, + .write =3D ima_measurements_staged_write, + .llseek =3D seq_lseek, + .release =3D ima_measurements_release, +}; + void ima_print_digest(struct seq_file *m, u8 *digest, u32 size) { u32 i; @@ -356,6 +436,28 @@ static const struct file_operations ima_ascii_measurem= ents_ops =3D { .release =3D ima_measurements_release, }; =20 +static const struct seq_operations ima_ascii_measurements_staged_seqops = =3D { + .start =3D ima_measurements_staged_start, + .next =3D ima_measurements_staged_next, + .stop =3D ima_measurements_stop, + .show =3D ima_ascii_measurements_show +}; + +static int ima_ascii_measurements_staged_open(struct inode *inode, + struct file *file) +{ + return _ima_measurements_open(inode, file, + &ima_ascii_measurements_staged_seqops); +} + +static const struct file_operations ima_ascii_measurements_staged_ops =3D { + .open =3D ima_ascii_measurements_staged_open, + .read =3D seq_read, + .write =3D ima_measurements_staged_write, + .llseek =3D seq_lseek, + .release =3D ima_measurements_release, +}; + static ssize_t ima_read_policy(char *path) { void *data =3D NULL; @@ -459,10 +561,21 @@ static const struct seq_operations ima_policy_seqops = =3D { }; #endif =20 -static int __init create_securityfs_measurement_lists(void) +static int __init create_securityfs_measurement_lists(bool staging) { + const struct file_operations *ascii_ops =3D &ima_ascii_measurements_ops; + const struct file_operations *binary_ops =3D &ima_measurements_ops; + mode_t permissions =3D S_IRUSR | S_IRGRP; + const char *file_suffix =3D ""; int count =3D NR_BANKS(ima_tpm_chip); =20 + if (staging) { + ascii_ops =3D &ima_ascii_measurements_staged_ops; + binary_ops =3D &ima_measurements_staged_ops; + file_suffix =3D "_staged"; + permissions |=3D (S_IWUSR | S_IWGRP); + } + if (ima_sha1_idx >=3D NR_BANKS(ima_tpm_chip)) count++; =20 @@ -473,29 +586,32 @@ static int __init create_securityfs_measurement_lists= (void) =20 if (algo =3D=3D HASH_ALGO__LAST) snprintf(file_name, sizeof(file_name), - "ascii_runtime_measurements_tpm_alg_%x", - ima_tpm_chip->allocated_banks[i].alg_id); + "ascii_runtime_measurements_tpm_alg_%x%s", + ima_tpm_chip->allocated_banks[i].alg_id, + file_suffix); else snprintf(file_name, sizeof(file_name), - "ascii_runtime_measurements_%s", - hash_algo_name[algo]); - dentry =3D securityfs_create_file(file_name, S_IRUSR | S_IRGRP, + "ascii_runtime_measurements_%s%s", + hash_algo_name[algo], file_suffix); + dentry =3D securityfs_create_file(file_name, permissions, ima_dir, (void *)(uintptr_t)i, - &ima_ascii_measurements_ops); + ascii_ops); if (IS_ERR(dentry)) return PTR_ERR(dentry); =20 if (algo =3D=3D HASH_ALGO__LAST) snprintf(file_name, sizeof(file_name), - "binary_runtime_measurements_tpm_alg_%x", - ima_tpm_chip->allocated_banks[i].alg_id); + "binary_runtime_measurements_tpm_alg_%x%s", + ima_tpm_chip->allocated_banks[i].alg_id, + file_suffix); else snprintf(file_name, sizeof(file_name), - "binary_runtime_measurements_%s", - hash_algo_name[algo]); - dentry =3D securityfs_create_file(file_name, S_IRUSR | S_IRGRP, + "binary_runtime_measurements_%s%s", + hash_algo_name[algo], file_suffix); + + dentry =3D securityfs_create_file(file_name, permissions, ima_dir, (void *)(uintptr_t)i, - &ima_measurements_ops); + binary_ops); if (IS_ERR(dentry)) return PTR_ERR(dentry); } @@ -503,6 +619,23 @@ static int __init create_securityfs_measurement_lists(= void) return 0; } =20 +static int __init create_securityfs_staging_links(void) +{ + struct dentry *dentry; + + dentry =3D securityfs_create_symlink("binary_runtime_measurements_staged", + ima_dir, "binary_runtime_measurements_sha1_staged", NULL); + if (IS_ERR(dentry)) + return PTR_ERR(dentry); + + dentry =3D securityfs_create_symlink("ascii_runtime_measurements_staged", + ima_dir, "ascii_runtime_measurements_sha1_staged", NULL); + if (IS_ERR(dentry)) + return PTR_ERR(dentry); + + return 0; +} + /* * ima_open_policy: sequentialize access to the policy file */ @@ -595,7 +728,13 @@ int __init ima_fs_init(void) goto out; } =20 - ret =3D create_securityfs_measurement_lists(); + ret =3D create_securityfs_measurement_lists(false); + if (ret =3D=3D 0 && IS_ENABLED(CONFIG_IMA_STAGING)) { + ret =3D create_securityfs_measurement_lists(true); + if (ret =3D=3D 0) + ret =3D create_securityfs_staging_links(); + } + if (ret !=3D 0) goto out; =20 diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/im= a_kexec.c index d7d0fb639d99..d5503dd5cc9b 100644 --- a/security/integrity/ima/ima_kexec.c +++ b/security/integrity/ima/ima_kexec.c @@ -42,8 +42,8 @@ void ima_measure_kexec_event(const char *event_name) long len; int n; =20 - buf_size =3D ima_get_binary_runtime_size(BINARY); - len =3D atomic_long_read(&ima_num_entries[BINARY]); + buf_size =3D ima_get_binary_runtime_size(BINARY_FULL); + len =3D atomic_long_read(&ima_num_entries[BINARY_FULL]); =20 n =3D scnprintf(ima_kexec_event, IMA_KEXEC_EVENT_LEN, "kexec_segment_size=3D%lu;ima_binary_runtime_size=3D%lu;" @@ -106,13 +106,26 @@ static int ima_dump_measurement_list(unsigned long *b= uffer_size, void **buffer, =20 memset(&khdr, 0, sizeof(khdr)); khdr.version =3D 1; - /* This is an append-only list, no need to hold the RCU read lock */ - list_for_each_entry_rcu(qe, &ima_measurements, later, true) { + /* It can race with ima_queue_stage() and ima_queue_delete_staged(). */ + mutex_lock(&ima_extend_list_mutex); + + list_for_each_entry_rcu(qe, &ima_measurements_staged, later, + lockdep_is_held(&ima_extend_list_mutex)) { ret =3D ima_dump_measurement(&khdr, qe); if (ret < 0) break; } =20 + list_for_each_entry_rcu(qe, &ima_measurements, later, + lockdep_is_held(&ima_extend_list_mutex)) { + if (!ret) + ret =3D ima_dump_measurement(&khdr, qe); + if (ret < 0) + break; + } + + mutex_unlock(&ima_extend_list_mutex); + /* * fill in reserved space with some buffer details * (eg. version, buffer size, number of measurements) @@ -167,6 +180,7 @@ void ima_add_kexec_buffer(struct kimage *image) extra_memory =3D CONFIG_IMA_KEXEC_EXTRA_MEMORY_KB * 1024; =20 binary_runtime_size =3D ima_get_binary_runtime_size(BINARY) + + ima_get_binary_runtime_size(BINARY_STAGED) + extra_memory; =20 if (binary_runtime_size >=3D ULONG_MAX - PAGE_SIZE) diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/im= a_queue.c index b6d10dceb669..50519ed837d4 100644 --- a/security/integrity/ima/ima_queue.c +++ b/security/integrity/ima/ima_queue.c @@ -26,6 +26,7 @@ static struct tpm_digest *digests; =20 LIST_HEAD(ima_measurements); /* list of all measurements */ +LIST_HEAD(ima_measurements_staged); /* list of staged measurements */ #ifdef CONFIG_IMA_KEXEC static unsigned long binary_runtime_size[BINARY__LAST]; #else @@ -45,11 +46,11 @@ atomic_long_t ima_num_violations =3D ATOMIC_LONG_INIT(0= ); /* key: inode (before secure-hashing a file) */ struct hlist_head __rcu *ima_htable; =20 -/* mutex protects atomicity of extending measurement list +/* mutex protects atomicity of extending and staging measurement list * and extending the TPM PCR aggregate. Since tpm_extend can take * long (and the tpm driver uses a mutex), we can't use the spinlock. */ -static DEFINE_MUTEX(ima_extend_list_mutex); +DEFINE_MUTEX(ima_extend_list_mutex); =20 /* * Used internally by the kernel to suspend measurements. @@ -174,12 +175,16 @@ static int ima_add_digest_entry(struct ima_template_e= ntry *entry, lockdep_is_held(&ima_extend_list_mutex)); =20 atomic_long_inc(&ima_num_entries[BINARY]); + atomic_long_inc(&ima_num_entries[BINARY_FULL]); + if (update_htable) { key =3D ima_hash_key(entry->digests[ima_hash_algo_idx].digest); hlist_add_head_rcu(&qe->hnext, &htable[key]); } =20 ima_update_binary_runtime_size(entry, BINARY); + ima_update_binary_runtime_size(entry, BINARY_FULL); + return 0; } =20 @@ -280,6 +285,94 @@ int ima_add_template_entry(struct ima_template_entry *= entry, int violation, return result; } =20 +int ima_queue_stage(void) +{ + int ret =3D 0; + + mutex_lock(&ima_extend_list_mutex); + if (!list_empty(&ima_measurements_staged)) { + ret =3D -EEXIST; + goto out_unlock; + } + + if (list_empty(&ima_measurements)) { + ret =3D -ENOENT; + goto out_unlock; + } + + list_replace(&ima_measurements, &ima_measurements_staged); + INIT_LIST_HEAD(&ima_measurements); + + atomic_long_set(&ima_num_entries[BINARY_STAGED], + atomic_long_read(&ima_num_entries[BINARY])); + atomic_long_set(&ima_num_entries[BINARY], 0); + + if (IS_ENABLED(CONFIG_IMA_KEXEC)) { + binary_runtime_size[BINARY_STAGED] =3D + binary_runtime_size[BINARY]; + binary_runtime_size[BINARY] =3D 0; + } +out_unlock: + mutex_unlock(&ima_extend_list_mutex); + return ret; +} + +static void ima_queue_delete(struct list_head *head); + +int ima_queue_staged_delete_all(void) +{ + LIST_HEAD(ima_measurements_trim); + + mutex_lock(&ima_extend_list_mutex); + if (list_empty(&ima_measurements_staged)) { + mutex_unlock(&ima_extend_list_mutex); + return -ENOENT; + } + + list_replace(&ima_measurements_staged, &ima_measurements_trim); + INIT_LIST_HEAD(&ima_measurements_staged); + + atomic_long_set(&ima_num_entries[BINARY_STAGED], 0); + + if (IS_ENABLED(CONFIG_IMA_KEXEC)) + binary_runtime_size[BINARY_STAGED] =3D 0; + + mutex_unlock(&ima_extend_list_mutex); + + ima_queue_delete(&ima_measurements_trim); + return 0; +} + +static void ima_queue_delete(struct list_head *head) +{ + struct ima_queue_entry *qe, *qe_tmp; + unsigned int i; + + list_for_each_entry_safe(qe, qe_tmp, head, later) { + /* + * Safe to free template_data here without synchronize_rcu() + * because the only htable reader, ima_lookup_digest_entry(), + * accesses only entry->digests, not template_data. 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spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.18.224.235]) by frasgout12.his.huawei.com (SkyGuard) with ESMTPS id 4fhW3x5hrfztKRF; Fri, 27 Mar 2026 01:29:33 +0800 (CST) Received: from mail02.huawei.com (unknown [7.182.16.47]) by mail.maildlp.com (Postfix) with ESMTP id 3C0D840560; Fri, 27 Mar 2026 01:33:10 +0800 (CST) Received: from huaweicloud.com (unknown [10.204.63.22]) by APP1 (Coremail) with SMTP id LxC2BwCHcu_MbcVpXmwvAQ--.1493S2; Thu, 26 Mar 2026 18:33:09 +0100 (CET) From: Roberto Sassu To: corbet@lwn.net, skhan@linuxfoundation.org, zohar@linux.ibm.com, dmitry.kasatkin@gmail.com, eric.snowberg@oracle.com, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, gregorylumen@linux.microsoft.com, chenste@linux.microsoft.com, nramas@linux.microsoft.com, Roberto Sassu Subject: [PATCH v4 10/13] ima: Add support for flushing the hash table when staging measurements Date: Thu, 26 Mar 2026 18:30:08 +0100 Message-ID: <20260326173011.1191815-11-roberto.sassu@huaweicloud.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260326173011.1191815-1-roberto.sassu@huaweicloud.com> References: <20260326173011.1191815-1-roberto.sassu@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: LxC2BwCHcu_MbcVpXmwvAQ--.1493S2 X-Coremail-Antispam: 1UD129KBjvJXoWxJF1xtFyruFWrJw4UXFWDArb_yoWrAFWUpa ykWry8KrZ5JF1vgry8ArZ3AFya9397WF1UGw4rG3s5JF15Xr4jgF1akryS9Fn5uryrtF1f tr4aqr4Yya1rtrJanT9S1TB71UUUUUDqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUvvb4IE77IF4wAFF20E14v26ryj6rWUM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4 vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Xr0_Ar1l84ACjcxK6xIIjxv20xvEc7Cj xVAFwI0_Gr1j6F4UJwA2z4x0Y4vEx4A2jsIE14v26r4j6F4UM28EF7xvwVC2z280aVCY1x 0267AKxVW8Jr0_Cr1UM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02 F40Ex7xfMcIj6xIIjxv20xvE14v26r1Y6r17McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4I kC6x0Yz7v_Jr0_Gr1lF7xvr2IYc2Ij64vIr41lFIxGxcIEc7CjxVA2Y2ka0xkIwI1lc7Cj xVAaw2AFwI0_Wrv_ZF1l42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2 IqxVAqx4xG67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v2 6r4a6rW5MIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Xr0_Ar1lIxAIcVC0I7IYx2 IY6xkF7I0E14v26r4UJVWxJr1lIxAIcVCF04k26cxKx2IYs7xG6r1j6r1xMIIF0xvEx4A2 jsIE14v26r4j6F4UMIIF0xvEx4A2jsIEc7CjxVAFwI0_Gr1j6F4UJbIYCTnIWIevJa73Uj IFyTuYvjxUVHqcUUUUU X-CM-SenderInfo: purev21wro2thvvxqx5xdzvxpfor3voofrz/1tbiAgAEBGnEnS4T7QAAsi Content-Type: text/plain; charset="utf-8" From: Roberto Sassu Introduce the new kernel option ima_flush_htable to decide whether or not the digests of staged measurement entries are flushed from the hash table, when they are deleted. When the option is enabled, replace the old hash table with a new one, by calling ima_alloc_replace_htable(), and completely delete the measurements entries. Note: This code derives from the Alt-IMA Huawei project, whose license is GPL-2.0 OR MIT. Link: https://github.com/linux-integrity/linux/issues/1 Signed-off-by: Roberto Sassu --- .../admin-guide/kernel-parameters.txt | 4 +++ security/integrity/ima/ima.h | 1 + security/integrity/ima/ima_queue.c | 36 ++++++++++++++++--- 3 files changed, 37 insertions(+), 4 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentatio= n/admin-guide/kernel-parameters.txt index 89670c5e7c8e..a651a3864dcf 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2345,6 +2345,10 @@ Kernel parameters Use the canonical format for the binary runtime measurements, instead of host native format. =20 + ima_flush_htable [IMA] + Flush the IMA hash table when deleting all the + staged measurement entries. + ima_hash=3D [IMA] Format: { md5 | sha1 | rmd160 | sha256 | sha384 | sha512 | ... } diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index 65db152a0a24..699b735dec7d 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -340,6 +340,7 @@ extern atomic_long_t ima_num_entries[BINARY__LAST]; extern atomic_long_t ima_num_violations; extern struct hlist_head __rcu *ima_htable; extern struct mutex ima_extend_list_mutex; +extern bool ima_flush_htable; =20 static inline unsigned int ima_hash_key(u8 *digest) { diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/im= a_queue.c index 50519ed837d4..f5c18acfbc43 100644 --- a/security/integrity/ima/ima_queue.c +++ b/security/integrity/ima/ima_queue.c @@ -22,6 +22,20 @@ =20 #define AUDIT_CAUSE_LEN_MAX 32 =20 +bool ima_flush_htable; + +static int __init ima_flush_htable_setup(char *str) +{ + if (IS_ENABLED(CONFIG_IMA_DISABLE_HTABLE)) { + pr_warn("Hash table not enabled, ignoring request to flush\n"); + return 1; + } + + ima_flush_htable =3D true; + return 1; +} +__setup("ima_flush_htable", ima_flush_htable_setup); + /* pre-allocated array of tpm_digest structures to extend a PCR */ static struct tpm_digest *digests; =20 @@ -317,10 +331,11 @@ int ima_queue_stage(void) return ret; } =20 -static void ima_queue_delete(struct list_head *head); +static void ima_queue_delete(struct list_head *head, bool flush_htable); =20 int ima_queue_staged_delete_all(void) { + struct hlist_head *old_queue =3D NULL; LIST_HEAD(ima_measurements_trim); =20 mutex_lock(&ima_extend_list_mutex); @@ -337,13 +352,26 @@ int ima_queue_staged_delete_all(void) if (IS_ENABLED(CONFIG_IMA_KEXEC)) binary_runtime_size[BINARY_STAGED] =3D 0; =20 + if (ima_flush_htable) { + old_queue =3D ima_alloc_replace_htable(); + if (IS_ERR(old_queue)) { + mutex_unlock(&ima_extend_list_mutex); + return PTR_ERR(old_queue); + } + } + mutex_unlock(&ima_extend_list_mutex); =20 - ima_queue_delete(&ima_measurements_trim); + if (ima_flush_htable) { + synchronize_rcu(); + kfree(old_queue); + } + + ima_queue_delete(&ima_measurements_trim, ima_flush_htable); return 0; } =20 -static void ima_queue_delete(struct list_head *head) +static void ima_queue_delete(struct list_head *head, bool flush_htable) { struct ima_queue_entry *qe, *qe_tmp; unsigned int i; @@ -365,7 +393,7 @@ static void ima_queue_delete(struct list_head *head) list_del(&qe->later); 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Fri, 27 Mar 2026 01:33:18 +0800 (CST) Received: from huaweicloud.com (unknown [10.204.63.22]) by APP1 (Coremail) with SMTP id LxC2BwCHcu_MbcVpXmwvAQ--.1493S3; Thu, 26 Mar 2026 18:33:17 +0100 (CET) From: Roberto Sassu To: corbet@lwn.net, skhan@linuxfoundation.org, zohar@linux.ibm.com, dmitry.kasatkin@gmail.com, eric.snowberg@oracle.com, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, gregorylumen@linux.microsoft.com, chenste@linux.microsoft.com, nramas@linux.microsoft.com, Roberto Sassu Subject: [PATCH v4 11/13] ima: Support staging and deleting N measurements entries Date: Thu, 26 Mar 2026 18:30:09 +0100 Message-ID: <20260326173011.1191815-12-roberto.sassu@huaweicloud.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260326173011.1191815-1-roberto.sassu@huaweicloud.com> References: <20260326173011.1191815-1-roberto.sassu@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: LxC2BwCHcu_MbcVpXmwvAQ--.1493S3 X-Coremail-Antispam: 1UD129KBjvJXoWxKFyfCw43Kw13CrWUAw43Jrb_yoWxKrykpa 90ga48Cry8JryxKrykGas7Ars5W3ykGF1UGw43GasFyF13XFyj9rnxAFy2kFs8CrZ5Xr4f twsIqrs8Can0yaDanT9S1TB71UUUUUDqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUPqb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28IrcIa0xkI8VA2jI8067AKxVWUGw A2048vs2IY020Ec7CjxVAFwI0_Gr0_Xr1l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0rcxS w2x7M28EF7xvwVC0I7IYx2IY67AKxVW5JVW7JwA2z4x0Y4vE2Ix0cI8IcVCY1x0267AKxV W8Jr0_Cr1UM28EF7xvwVC2z280aVAFwI0_Gr0_Cr1l84ACjcxK6I8E87Iv6xkF7I0E14v2 6r4UJVWxJr1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2 WlYx0E2Ix0cI8IcVAFwI0_Jrv_JF1lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkE bVWUJVW8JwACjcxG0xvY0x0EwIxGrwACI402YVCY1x02628vn2kIc2xKxwCY1x0262kKe7 AKxVWrXVW3AwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02 F40E14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_GFv_Wr ylIxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVW5JVW7JwCI42IY6xIIjxv20xvEc7Cj xVAFwI0_Gr1j6F4UJwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI 0_Gr0_Cr1lIxAIcVC2z280aVCY1x0267AKxVW8Jr0_Cr1UYxBIdaVFxhVjvjDU0xZFpf9x 07jQ4SrUUUUU= X-CM-SenderInfo: purev21wro2thvvxqx5xdzvxpfor3voofrz/1tbiAgAEBGnEnS4T7QABsj Content-Type: text/plain; charset="utf-8" From: Roberto Sassu Add support for sending a value N between 1 and ULONG_MAX to the staging interface. This value represents the number of measurements that should be deleted from the current measurements list. This staging method allows the remote attestation agents to easily separate the measurements that were verified (staged and deleted) from those that weren't due to the race between taking a TPM quote and reading the measurements list. In order to minimize the locking time of ima_extend_list_mutex, deleting N entries is realized by staging the entire current measurements list (with the lock), by determining the N-th staged entry (without the lock), and by splicing the entries in excess back to the current measurements list (with the lock). Finally, the N entries are deleted (without the lock). Flushing the hash table is not supported for N entries, since it would require removing the N entries one by one from the hash table under the ima_extend_list_mutex lock, which would increase the locking time. The ima_extend_list_mutex lock is necessary in ima_dump_measurement_list() because ima_queue_staged_delete_partial() uses __list_cut_position() to modify ima_measurements_staged, for which no RCU-safe variant exists. For the staging with prompt flavor alone, list_replace_rcu() could have been used instead, but since both flavors share the same kexec serialization path, the mutex is required regardless. Link: https://github.com/linux-integrity/linux/issues/1 Suggested-by: Steven Chen Signed-off-by: Roberto Sassu --- security/integrity/ima/Kconfig | 3 ++ security/integrity/ima/ima.h | 1 + security/integrity/ima/ima_fs.c | 22 +++++++++- security/integrity/ima/ima_queue.c | 70 ++++++++++++++++++++++++++++++ 4 files changed, 95 insertions(+), 1 deletion(-) diff --git a/security/integrity/ima/Kconfig b/security/integrity/ima/Kconfig index e714726f3384..6ddb4e77bff5 100644 --- a/security/integrity/ima/Kconfig +++ b/security/integrity/ima/Kconfig @@ -341,6 +341,9 @@ config IMA_STAGING It allows user space to stage the measurements list for deletion and to delete the staged measurements after confirmation. =20 + Or, alternatively, it allows user space to specify N measurements + entries to be deleted. + On kexec, staging is reverted and staged measurements are prepended to the current measurements list when measurements are copied to the secondary kernel. diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index 699b735dec7d..de0693fce53c 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -319,6 +319,7 @@ struct ima_template_desc *lookup_template_desc(const ch= ar *name); bool ima_template_has_modsig(const struct ima_template_desc *ima_template); int ima_queue_stage(void); int ima_queue_staged_delete_all(void); +int ima_queue_staged_delete_partial(unsigned long req_value); int ima_restore_measurement_entry(struct ima_template_entry *entry); int ima_restore_measurement_list(loff_t bufsize, void *buf); int ima_measurements_show(struct seq_file *m, void *v); diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_f= s.c index 39d9128e9f22..eb3f343c1138 100644 --- a/security/integrity/ima/ima_fs.c +++ b/security/integrity/ima/ima_fs.c @@ -28,6 +28,7 @@ * Requests: * 'A\n': stage the entire measurements list * 'D\n': delete all staged measurements + * '[1, ULONG_MAX]\n' delete N measurements entries */ #define STAGED_REQ_LENGTH 21 =20 @@ -319,6 +320,7 @@ static ssize_t ima_measurements_staged_write(struct fil= e *file, size_t datalen, loff_t *ppos) { char req[STAGED_REQ_LENGTH]; + unsigned long req_value; int ret; =20 if (*ppos > 0 || datalen < 2 || datalen > STAGED_REQ_LENGTH) @@ -346,7 +348,25 @@ static ssize_t ima_measurements_staged_write(struct fi= le *file, ret =3D ima_queue_staged_delete_all(); break; default: - ret =3D -EINVAL; + if (ima_flush_htable) { + pr_debug("Deleting staged N measurements not supported when flushing th= e hash table is requested\n"); + return -EINVAL; + } + + ret =3D kstrtoul(req, 10, &req_value); + if (ret < 0) + return ret; + + if (req_value =3D=3D 0) { + pr_debug("Must delete at least one entry\n"); + return -EINVAL; + } + + ret =3D ima_queue_stage(); + if (ret < 0) + return ret; + + ret =3D ima_queue_staged_delete_partial(req_value); } =20 if (ret < 0) diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/im= a_queue.c index f5c18acfbc43..4fb557d61a88 100644 --- a/security/integrity/ima/ima_queue.c +++ b/security/integrity/ima/ima_queue.c @@ -371,6 +371,76 @@ int ima_queue_staged_delete_all(void) return 0; } =20 +int ima_queue_staged_delete_partial(unsigned long req_value) +{ + unsigned long req_value_copy =3D req_value; + unsigned long size_to_remove =3D 0, num_to_remove =3D 0; + struct list_head *cut_pos =3D NULL; + LIST_HEAD(ima_measurements_trim); + struct ima_queue_entry *qe; + int ret =3D 0; + + /* + * Safe walk (no concurrent write), not under ima_extend_list_mutex + * for performance reasons. + */ + list_for_each_entry(qe, &ima_measurements_staged, later) { + size_to_remove +=3D get_binary_runtime_size(qe->entry); + num_to_remove++; + + if (--req_value_copy =3D=3D 0) { + /* qe->later always points to a valid list entry. */ + cut_pos =3D &qe->later; + break; + } + } + + /* Nothing to remove, undoing staging. */ + if (req_value_copy > 0) { + size_to_remove =3D 0; + num_to_remove =3D 0; + ret =3D -ENOENT; + } + + mutex_lock(&ima_extend_list_mutex); + if (list_empty(&ima_measurements_staged)) { + mutex_unlock(&ima_extend_list_mutex); + return -ENOENT; + } + + if (cut_pos !=3D NULL) + /* + * ima_dump_measurement_list() does not modify the list, + * cut_pos remains the same even if it was computed before + * the lock. + */ + __list_cut_position(&ima_measurements_trim, + &ima_measurements_staged, cut_pos); + + atomic_long_sub(num_to_remove, &ima_num_entries[BINARY_STAGED]); 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dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.18.224.196]) by frasgout12.his.huawei.com (SkyGuard) with ESMTPS id 4fhW4G1S18ztKRH; Fri, 27 Mar 2026 01:29:50 +0800 (CST) Received: from mail02.huawei.com (unknown [7.182.16.47]) by mail.maildlp.com (Postfix) with ESMTP id 9E3A14056B; Fri, 27 Mar 2026 01:33:26 +0800 (CST) Received: from huaweicloud.com (unknown [10.204.63.22]) by APP1 (Coremail) with SMTP id LxC2BwCHcu_MbcVpXmwvAQ--.1493S4; Thu, 26 Mar 2026 18:33:26 +0100 (CET) From: Roberto Sassu To: corbet@lwn.net, skhan@linuxfoundation.org, zohar@linux.ibm.com, dmitry.kasatkin@gmail.com, eric.snowberg@oracle.com, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, gregorylumen@linux.microsoft.com, chenste@linux.microsoft.com, nramas@linux.microsoft.com, Roberto Sassu Subject: [PATCH v4 12/13] ima: Return error on deleting staged measurements after kexec Date: Thu, 26 Mar 2026 18:30:10 +0100 Message-ID: <20260326173011.1191815-13-roberto.sassu@huaweicloud.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260326173011.1191815-1-roberto.sassu@huaweicloud.com> References: <20260326173011.1191815-1-roberto.sassu@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: LxC2BwCHcu_MbcVpXmwvAQ--.1493S4 X-Coremail-Antispam: 1UD129KBjvJXoWxJF1kAFy7XFy5uFWUGr18uFg_yoW5Cw1kpa sFgFWUCr4UJFyxKrykGa43Cr4Fk39YgF4UGwsxG3Z2yF1rWFyj9rnxAr12krn8KrW5tF1x twsIqr45Aa1DtaDanT9S1TB71UUUUUDqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUPqb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28IrcIa0xkI8VA2jI8067AKxVWUXw A2048vs2IY020Ec7CjxVAFwI0_Xr0E3s1l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0rcxS w2x7M28EF7xvwVC0I7IYx2IY67AKxVW5JVW7JwA2z4x0Y4vE2Ix0cI8IcVCY1x0267AKxV W8Jr0_Cr1UM28EF7xvwVC2z280aVAFwI0_Gr0_Cr1l84ACjcxK6I8E87Iv6xkF7I0E14v2 6r4UJVWxJr1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2 WlYx0E2Ix0cI8IcVAFwI0_Jrv_JF1lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkE bVWUJVW8JwACjcxG0xvY0x0EwIxGrwACI402YVCY1x02628vn2kIc2xKxwCY1x0262kKe7 AKxVWrXVW3AwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02 F40E14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_GFv_Wr ylIxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVW5JVW7JwCI42IY6xIIjxv20xvEc7Cj xVAFwI0_Gr1j6F4UJwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI 0_Gr0_Cr1lIxAIcVC2z280aVCY1x0267AKxVW8Jr0_Cr1UYxBIdaVFxhVjvjDU0xZFpf9x 07jh6pPUUUUU= X-CM-SenderInfo: purev21wro2thvvxqx5xdzvxpfor3voofrz/1tbiAgAEBGnEnS4T7QACsg Content-Type: text/plain; charset="utf-8" From: Roberto Sassu Refuse to delete staged measurements (both with prompt and without) if a kexec racing with the deletion already prepended staged measurements in the kexec buffer. In this way, user space becomes aware that staged measurements are going to appear in the secondary kernel, and thus they don't have to be saved twice. Link: https://github.com/linux-integrity/linux/issues/1 Signed-off-by: Roberto Sassu --- security/integrity/ima/ima.h | 1 + security/integrity/ima/ima_kexec.c | 3 +++ security/integrity/ima/ima_queue.c | 17 +++++++++++++++++ 3 files changed, 21 insertions(+) diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index de0693fce53c..0816b69f7c39 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -342,6 +342,7 @@ extern atomic_long_t ima_num_violations; extern struct hlist_head __rcu *ima_htable; extern struct mutex ima_extend_list_mutex; extern bool ima_flush_htable; +extern bool ima_staged_measurements_prepended; =20 static inline unsigned int ima_hash_key(u8 *digest) { diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/im= a_kexec.c index d5503dd5cc9b..25c8356be22a 100644 --- a/security/integrity/ima/ima_kexec.c +++ b/security/integrity/ima/ima_kexec.c @@ -116,6 +116,9 @@ static int ima_dump_measurement_list(unsigned long *buf= fer_size, void **buffer, break; } =20 + if (!list_empty(&ima_measurements_staged)) + ima_staged_measurements_prepended =3D true; + list_for_each_entry_rcu(qe, &ima_measurements, later, lockdep_is_held(&ima_extend_list_mutex)) { if (!ret) diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/im= a_queue.c index 4fb557d61a88..1918c8ea9abb 100644 --- a/security/integrity/ima/ima_queue.c +++ b/security/integrity/ima/ima_queue.c @@ -72,6 +72,13 @@ DEFINE_MUTEX(ima_extend_list_mutex); */ static bool ima_measurements_suspended; =20 +/* + * Used to determine if staged measurements were prepended during kexec, + * so that an error can be sent to user space during deletion, and they do= n't + * store staged measurements twice. + */ +bool ima_staged_measurements_prepended; + /* Callers must call synchronize_rcu() and free the hash table. */ static struct hlist_head *ima_alloc_replace_htable(void) { @@ -344,6 +351,11 @@ int ima_queue_staged_delete_all(void) return -ENOENT; } =20 + if (ima_staged_measurements_prepended) { + mutex_unlock(&ima_extend_list_mutex); + return -ESTALE; + } + list_replace(&ima_measurements_staged, &ima_measurements_trim); INIT_LIST_HEAD(&ima_measurements_staged); =20 @@ -408,6 +420,11 @@ int ima_queue_staged_delete_partial(unsigned long req_= value) return -ENOENT; } =20 + if (ima_staged_measurements_prepended) { + mutex_unlock(&ima_extend_list_mutex); + return -ESTALE; + } + if (cut_pos !=3D NULL) /* * ima_dump_measurement_list() does not modify the list, --=20 2.43.0 From nobody Thu Apr 2 18:49:56 2026 Received: from frasgout11.his.huawei.com (frasgout11.his.huawei.com [14.137.139.23]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BBC1E426D0C; Thu, 26 Mar 2026 17:33:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=14.137.139.23 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774546421; cv=none; b=TyLKsoPEU9YDVxv+N9VUETRjXiJ8PrtZVJUh1Z5kFl0G57X8iVaUzm6usmOL3eDoOy+dl99AvMpI2AJceSZmDcbcFlIW9qTJQB+X+2pSIvN4QBakeDNEUJVqDAS+ikiU8qy0jO77H4L882KOnB5kAaNeOxGSQh3YqgBjcqZkTGI= ARC-Message-Signature: i=1; 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Fri, 27 Mar 2026 01:33:34 +0800 (CST) Received: from huaweicloud.com (unknown [10.204.63.22]) by APP1 (Coremail) with SMTP id LxC2BwCHcu_MbcVpXmwvAQ--.1493S5; Thu, 26 Mar 2026 18:33:34 +0100 (CET) From: Roberto Sassu To: corbet@lwn.net, skhan@linuxfoundation.org, zohar@linux.ibm.com, dmitry.kasatkin@gmail.com, eric.snowberg@oracle.com, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, gregorylumen@linux.microsoft.com, chenste@linux.microsoft.com, nramas@linux.microsoft.com, Roberto Sassu Subject: [PATCH v4 13/13] doc: security: Add documentation of the IMA staging mechanism Date: Thu, 26 Mar 2026 18:30:11 +0100 Message-ID: <20260326173011.1191815-14-roberto.sassu@huaweicloud.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260326173011.1191815-1-roberto.sassu@huaweicloud.com> References: <20260326173011.1191815-1-roberto.sassu@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: LxC2BwCHcu_MbcVpXmwvAQ--.1493S5 X-Coremail-Antispam: 1UD129KBjvJXoW3XFW7Xw18WrWrJF1rXF4Dtwb_yoW3tr45pa 9IgFyfCwn5Ja4xJw1rJw1xGr1ru3yfGa1UCrn3tw1xtFn8Wryvvr4akrWY9FsxKr10vrWY v3ZFvr45Aw4qqFJanT9S1TB71UUUUUDqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUPqb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28IrcIa0xkI8VA2jI8067AKxVWUWw A2048vs2IY020Ec7CjxVAFwI0_Xr0E3s1l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0rcxS w2x7M28EF7xvwVC0I7IYx2IY67AKxVW5JVW7JwA2z4x0Y4vE2Ix0cI8IcVCY1x0267AKxV W8Jr0_Cr1UM28EF7xvwVC2z280aVAFwI0_Gr0_Cr1l84ACjcxK6I8E87Iv6xkF7I0E14v2 6r4UJVWxJr1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2 WlYx0E2Ix0cI8IcVAFwI0_Jrv_JF1lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkE bVWUJVW8JwACjcxG0xvY0x0EwIxGrwACI402YVCY1x02628vn2kIc2xKxwCY1x0262kKe7 AKxVWrXVW3AwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02 F40E14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_GFv_Wr ylIxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVW5JVW7JwCI42IY6xIIjxv20xvEc7Cj xVAFwI0_Gr1j6F4UJwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI 0_Gr0_Cr1lIxAIcVC2z280aVCY1x0267AKxVW8Jr0_Cr1UYxBIdaVFxhVjvjDU0xZFpf9x 07jSiihUUUUU= X-CM-SenderInfo: purev21wro2thvvxqx5xdzvxpfor3voofrz/1tbiAQAEBGnEnSsT4AAAsp Content-Type: text/plain; charset="utf-8" From: Roberto Sassu Add the documentation of the IMA staging mechanism in Documentation/security/IMA-staging.rst. Also add the missing Documentation/security/IMA-templates.rst file in MAINTAINERS. Signed-off-by: Roberto Sassu --- Documentation/security/IMA-staging.rst | 159 +++++++++++++++++++++++++ Documentation/security/index.rst | 1 + MAINTAINERS | 2 + 3 files changed, 162 insertions(+) create mode 100644 Documentation/security/IMA-staging.rst diff --git a/Documentation/security/IMA-staging.rst b/Documentation/securit= y/IMA-staging.rst new file mode 100644 index 000000000000..d0c27c0435c0 --- /dev/null +++ b/Documentation/security/IMA-staging.rst @@ -0,0 +1,159 @@ +.. SPDX-License-Identifier: GPL-2.0 + +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D +IMA Measurements Staging Mechanism +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D + + +Introduction +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D + +The IMA measurements list is currently stored in the kernel memory. Memory +occupation grows linearly with the number of entries, and can become a +problem especially in environments with reduced resources. + +While there is an advantage in keeping the IMA measurements list in kernel +memory, so that it is always available for reading from the securityfs +interfaces, storing it elsewhere would make it possible to free precious +memory for other kernel components. + +Storing the IMA measurements list outside the kernel does not introduce +security issues, since its integrity is anyway protected by the TPM. + +Hence, the new IMA staging mechanism is introduced to allow user space +to remove the desired portion of the measurements list from the kernel. + + +Usage +=3D=3D=3D=3D=3D + +The IMA staging mechanism can be enabled from the kernel configuration with +the CONFIG_IMA_STAGING option. + +If it is enabled, IMA duplicates the current measurements interfaces (both +binary and ASCII), by adding the ``_staged`` file suffix. Unlike the +existing counterparts, the ``_staged`` interfaces have write permission for +the root user and group, and require the process to have CAP_SYS_ADMIN set. + +The staging mechanism supports two flavors. + + +Staging with prompt +~~~~~~~~~~~~~~~~~~~ + +This staging process is achieved with the following steps. + + 1. ``echo A > <_staged interface>``: the user requests IMA to stage the + entire measurements list; + 2. ``cat <_staged interface>``: the user reads the staged measurements; + 3. ``echo D > <_staged interface>`` : the user request IMA to delete + staged measurements. + + +Staging and deleting +~~~~~~~~~~~~~~~~~~~~ + +This staging process is achieved with the following steps. + + 1. ``cat <_non_staged interface>``: the user reads the current + measurements list and determines what the value N for staging should + be; + 2. ``echo N > <_staged interface>``: the user requests IMA to delete N + measurements from the current measurements list. + + +Interface Access +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D + +In order to avoid the IMA measurements list be suddenly truncated by the +staging mechanism during a read, or having multiple concurrent staging, a +semaphore-like locking scheme has been implemented on all the measurements +list interfaces. + +Multiple readers can access concurrently the non-staged interfaces, and +they can be in mutual exclusion with one writer accessing the staged +interfaces. + +If an illegal access occurs, the open to the measurements list interface is +denied. + + +Management of Staged Measurements +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D + +Since with the staging mechanism measurements entries are removed from the +kernel, the user needs to save the staged ones in a storage and concatenate +them together, so that it can present them to remote attestation agents as +if staging was never done. + +Coordination is necessary in the case where there are multiple actors +requesting measurements to be staged. + +In the staging with prompt case, the staging interface can be accessed only +by one actor at time, so the others will get an error until the former +closes it. Since the actors don't care about N, when they gain access to +the interface, they will get all the staged measurements at the time of +their request. + +In the case of staging and deleting, coordination is more important, since +there is the risk that two actors unaware of each other compute the value N +on the current measurements list and request IMA to stage N twice. + + +Remote Attestation Agent Workflow +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D + +Users can choose the staging method they find more appropriate for their +workflow. + +If, as an example, a remote attestation agent would like to present to the +remote attestation server only the measurements that are required to +verify the TPM quote, its workflow would be the following. + +With staging with prompt, the agent stages the current measurements list, +reads and stores the measurements in a storage and immediately requests +IMA to delete the staged measurements from kernel memory. Afterwards, it +calculates N by replaying the PCR extend on the stored measurements until +the calculated PCRs match the quoted PCRs. It then keeps the measurements +in excess for the next attestation request. + +At the next attestation request, the agent performs the same steps above, +and concatenates the new measurements to the ones in excess from the +previous request. Also in this case, the agent replays the PCR extend until +it matches the currently quoted PCRs, keeps the measurements in excess and +presents the new N measurements entries to the remote attestation server. + +With the staging with deleting method, the agents reads the current +measurements list, calculates N and requests IMA to delete only those. The +measurements in excess are kept in the IMA measurements list and can be +retrieved at the next remote attestation request. + +Kexec +=3D=3D=3D=3D=3D + +In the event a kexec() system call occurs between staging and deleting, the +staged measurements entries are prepended to the current measurements list= s, +so that they are both available when the secondary kernel starts. In that +case, IMA returns an error to the user when attempting to delete staged +measurements to notify about their copy to the kexec buffer, so that the +user does not store them twice. + + +Hash table +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D + +By default, the template digest of staged measurement entries are kept in +kernel memory (only template data are freed), to be able to detect +duplicate entries independently of staging. + +The new kernel option ``ima_flush_htable`` has been introduced to +explicitly request a complete deletion of the staged measurements, for +maximum kernel memory saving. If the option has been specified, duplicate +entries are still avoided on entries of the current measurements list, +but there can be duplicates between different groups of staged +measurements. + +Flushing the hash table is supported only for the staging with prompt +flavor. For the staging and deleting flavor, it would have been necessary +to lock the hot path adding new measurements for the time needed to remove +each staged measurement individually. diff --git a/Documentation/security/index.rst b/Documentation/security/inde= x.rst index 3e0a7114a862..cec064dc1c83 100644 --- a/Documentation/security/index.rst +++ b/Documentation/security/index.rst @@ -8,6 +8,7 @@ Security Documentation credentials snp-tdx-threat-model IMA-templates + IMA-staging keys/index lsm lsm-development diff --git a/MAINTAINERS b/MAINTAINERS index 04823afa8b74..e78dfb4f4482 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -12668,6 +12668,8 @@ R: Eric Snowberg L: linux-integrity@vger.kernel.org S: Supported T: git git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity= .git +F: Documentation/security/IMA-staging.rst +F: Documentation/security/IMA-templates.rst F: include/linux/secure_boot.h F: security/integrity/ F: security/integrity/ima/ --=20 2.43.0