From nobody Fri Dec 19 09:49:37 2025 Received: from mail-wr1-f74.google.com (mail-wr1-f74.google.com [209.85.221.74]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8232122091 for ; Mon, 18 Dec 2023 14:17:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--alpic.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="d3if3aAs" Received: by mail-wr1-f74.google.com with SMTP id ffacd0b85a97d-3366722026fso799670f8f.0 for ; Mon, 18 Dec 2023 06:17:26 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1702909045; x=1703513845; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=44dw+1MbFrV8dm3vgBswQyvwS3Dp0mHymbgWSDxJ4b4=; b=d3if3aAsu+tGgN2rNVliPhRAiwEdSPGcaNq0qf/Aab8oi84WbRt+aDjWHFeFuBlXMm 1kF1rd9kGiIJR69pJZLpj7g2oHDxyiZZuRteWfeIL/CGCDSyqCBClR4xbdcDNpBpUaq7 b3VsB53xNeDIYYpkLKoFR59toiyl6Nv5s/EDKtWrd3/2uTfl9kKHZKneiSan/y//Bzco bO7PgoB6+mXybiKUL9Ldyen6XkOJzdJMaxUB3Vw1Xt86RRzGXdelUwZSEsrRGdojNuqS eaO210dgIoGPjtj9wcbCL7UGzDiBQezGc6Ft5Lc45tuCPG/xjgnQsmn46041pb/ltBi6 1t4g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1702909045; x=1703513845; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=44dw+1MbFrV8dm3vgBswQyvwS3Dp0mHymbgWSDxJ4b4=; b=vzyI1heq012rjSI5U5a2724fd6E1Z/+ysxlXLcq2jqPJbR14l+EQ5jK17sOeeLqXRk oruWsZUQv97A/NAnBJNZS4szMK8chAA3sm/a0+i7EyYIhcBKJpkF/98Ivt91WaP3kejH afYPTwl0rebfH/XZA5gwoN60U1+JC+1Msl6uggbwyW5tWLeQAcWtfpCBSYutNgHBKKos /j66aFi3ZMw+8F1oUhECBHay2QWZ+wDYVE0TJo8UYdzS3BctG27mYTeYGYCqiLTKSyRy iYiijqbKqOpC/JC8s+gquiqmZHDoiqctLeXncz63lioTM0TCA/gjF3RemEWT4V0j/NDq FhSQ== X-Gm-Message-State: AOJu0Yw4dt2Ic3tAx0XiI8iZJHfDYLw/p/9Klgw/9qHfQQHp/WkIPP6Y tkAFDlb0bGF8l0pURhWeLlMz1TVJKQ== X-Google-Smtp-Source: AGHT+IGrzpN6d3kxEjH5SGgsV7I6GOM5TxLiko/VpzRBwSB3KAzF5SxT0a1LDJMp1jF3r1F8JbdXhGQb+w== X-Received: from alpic.c.googlers.com ([fda3:e722:ac3:cc00:28:9cb1:c0a8:1bf2]) (user=alpic job=sendgmr) by 2002:a5d:47ca:0:b0:336:5c04:90da with SMTP id o10-20020a5d47ca000000b003365c0490damr17367wrc.6.1702909044844; Mon, 18 Dec 2023 06:17:24 -0800 (PST) Date: Mon, 18 Dec 2023 15:16:45 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.43.0.472.g3155946c3a-goog Message-ID: <20231218141645.2548743-1-alpic@google.com> Subject: [PATCH] SELinux: Introduce security_file_ioctl_compat hook From: Alfred Piccioni To: Paul Moore , Stephen Smalley , Eric Paris Cc: stable@vger.kernel.org, selinux@vger.kernel.org, linux-kernel@vger.kernel.org, Alfred Piccioni Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Some ioctl commands do not require ioctl permission, but are routed to other permissions such as FILE_GETATTR or FILE_SETATTR. This routing is done by comparing the ioctl cmd to a set of 64-bit flags (FS_IOC_*). However, if a 32-bit process is running on a 64-bit kernel, it emits 32-bit flags (FS_IOC32_*) for certain ioctl operations. These flags are being checked erroneously, which leads to these ioctl operations being routed to the ioctl permission, rather than the correct file permissions. This was also noted in a RED-PEN finding from a while back - "/* RED-PEN how should LSM module know it's handling 32bit? */". This patch introduces a new hook, security_file_ioctl_compat, that is called from the compat ioctl syscal. All current LSMs have been changed to support this hook. Reviewing the three places where we are currently using security_file_ioctl, it appears that only SELinux needs a dedicated compat change; TOMOYO and SMACK appear to be functional without any change. Fixes: 0b24dcb7f2f7 ("Revert "selinux: simplify ioctl checking"") Signed-off-by: Alfred Piccioni Cc: stable@vger.kernel.org --- fs/ioctl.c | 3 +-- include/linux/lsm_hook_defs.h | 2 ++ include/linux/security.h | 7 +++++++ security/security.c | 17 +++++++++++++++++ security/selinux/hooks.c | 26 ++++++++++++++++++++++++++ security/smack/smack_lsm.c | 1 + security/tomoyo/tomoyo.c | 1 + 7 files changed, 55 insertions(+), 2 deletions(-) diff --git a/fs/ioctl.c b/fs/ioctl.c index f5fd99d6b0d4..76cf22ac97d7 100644 --- a/fs/ioctl.c +++ b/fs/ioctl.c @@ -920,8 +920,7 @@ COMPAT_SYSCALL_DEFINE3(ioctl, unsigned int, fd, unsigne= d int, cmd, if (!f.file) return -EBADF; =20 - /* RED-PEN how should LSM module know it's handling 32bit? */ - error =3D security_file_ioctl(f.file, cmd, arg); + error =3D security_file_ioctl_compat(f.file, cmd, arg); if (error) goto out; =20 diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index ac962c4cb44b..626aa8cf930d 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -171,6 +171,8 @@ LSM_HOOK(int, 0, file_alloc_security, struct file *file) LSM_HOOK(void, LSM_RET_VOID, file_free_security, struct file *file) LSM_HOOK(int, 0, file_ioctl, struct file *file, unsigned int cmd, unsigned long arg) +LSM_HOOK(int, 0, file_ioctl_compat, struct file *file, unsigned int cmd, + unsigned long arg) LSM_HOOK(int, 0, mmap_addr, unsigned long addr) LSM_HOOK(int, 0, mmap_file, struct file *file, unsigned long reqprot, unsigned long prot, unsigned long flags) diff --git a/include/linux/security.h b/include/linux/security.h index 5f16eecde00b..22a82b7c59f1 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -389,6 +389,7 @@ int security_file_permission(struct file *file, int mas= k); int security_file_alloc(struct file *file); void security_file_free(struct file *file); int security_file_ioctl(struct file *file, unsigned int cmd, unsigned long= arg); +int security_file_ioctl_compat(struct file *file, unsigned int cmd, unsign= ed long arg); int security_mmap_file(struct file *file, unsigned long prot, unsigned long flags); int security_mmap_addr(unsigned long addr); @@ -987,6 +988,12 @@ static inline int security_file_ioctl(struct file *fil= e, unsigned int cmd, return 0; } =20 +static inline int security_file_ioctl_compat(struct file *file, unsigned i= nt cmd, + unsigned long arg) +{ + return 0; +} + static inline int security_mmap_file(struct file *file, unsigned long prot, unsigned long flags) { diff --git a/security/security.c b/security/security.c index 23b129d482a7..5c16ffc99b1e 100644 --- a/security/security.c +++ b/security/security.c @@ -2648,6 +2648,23 @@ int security_file_ioctl(struct file *file, unsigned = int cmd, unsigned long arg) } EXPORT_SYMBOL_GPL(security_file_ioctl); =20 +/** + * security_file_ioctl_compat() - Check if an ioctl is allowed in 32-bit c= ompat mode + * @file: associated file + * @cmd: ioctl cmd + * @arg: ioctl arguments + * + * Compat version of security_file_ioctl() that correctly handles 32-bit p= rocesses + * running on 64-bit kernels. + * + * Return: Returns 0 if permission is granted. + */ +int security_file_ioctl_compat(struct file *file, unsigned int cmd, unsign= ed long arg) +{ + return call_int_hook(file_ioctl_compat, 0, file, cmd, arg); +} +EXPORT_SYMBOL_GPL(security_file_ioctl_compat); + static inline unsigned long mmap_prot(struct file *file, unsigned long pro= t) { /* diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 2aa0e219d721..de96d156e6ea 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -3731,6 +3731,31 @@ static int selinux_file_ioctl(struct file *file, uns= igned int cmd, return error; } =20 +static int selinux_file_ioctl_compat(struct file *file, unsigned int cmd, + unsigned long arg) +{ + // If we are in a 64-bit kernel running 32-bit userspace, we need to make + // sure we don't compare 32-bit flags to 64-bit flags. + switch (cmd) { + case FS_IOC32_GETFLAGS: + cmd =3D FS_IOC_GETFLAGS; + break; + case FS_IOC32_SETFLAGS: + cmd =3D FS_IOC_GETFLAGS; + break; + case FS_IOC32_GETVERSION: + cmd =3D FS_IOC_GETVERSION; + break; + case FS_IOC32_SETVERSION: + cmd =3D FS_IOC_SETVERSION; + break; + default: + break; + } + + return selinux_file_ioctl(file, cmd, arg); +} + static int default_noexec __ro_after_init; =20 static int file_map_prot_check(struct file *file, unsigned long prot, int = shared) @@ -7036,6 +7061,7 @@ static struct security_hook_list selinux_hooks[] __ro= _after_init =3D { LSM_HOOK_INIT(file_permission, selinux_file_permission), LSM_HOOK_INIT(file_alloc_security, selinux_file_alloc_security), LSM_HOOK_INIT(file_ioctl, selinux_file_ioctl), + LSM_HOOK_INIT(file_ioctl_compat, selinux_file_ioctl_compat), LSM_HOOK_INIT(mmap_file, selinux_mmap_file), LSM_HOOK_INIT(mmap_addr, selinux_mmap_addr), LSM_HOOK_INIT(file_mprotect, selinux_file_mprotect), diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c index 65130a791f57..1f1ea8529421 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -4973,6 +4973,7 @@ static struct security_hook_list smack_hooks[] __ro_a= fter_init =3D { =20 LSM_HOOK_INIT(file_alloc_security, smack_file_alloc_security), LSM_HOOK_INIT(file_ioctl, smack_file_ioctl), + LSM_HOOK_INIT(file_ioctl_compat, smack_file_ioctl), LSM_HOOK_INIT(file_lock, smack_file_lock), LSM_HOOK_INIT(file_fcntl, smack_file_fcntl), LSM_HOOK_INIT(mmap_file, smack_mmap_file), diff --git a/security/tomoyo/tomoyo.c b/security/tomoyo/tomoyo.c index 25006fddc964..298d182759c2 100644 --- a/security/tomoyo/tomoyo.c +++ b/security/tomoyo/tomoyo.c @@ -568,6 +568,7 @@ static struct security_hook_list tomoyo_hooks[] __ro_af= ter_init =3D { LSM_HOOK_INIT(path_rename, tomoyo_path_rename), LSM_HOOK_INIT(inode_getattr, tomoyo_inode_getattr), LSM_HOOK_INIT(file_ioctl, tomoyo_file_ioctl), + LSM_HOOK_INIT(file_ioctl_compat, tomoyo_file_ioctl), LSM_HOOK_INIT(path_chmod, tomoyo_path_chmod), LSM_HOOK_INIT(path_chown, tomoyo_path_chown), LSM_HOOK_INIT(path_chroot, tomoyo_path_chroot), base-commit: 196e95aa8305aecafc4e1857b7d3eff200d953b6 --=20 2.43.0.472.g3155946c3a-goog