From nobody Mon Dec 15 02:55:36 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 6DF53205502; Fri, 16 May 2025 11:25:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747394752; cv=none; b=p7EdDWvIO2Nwt4zoRo7ie/uD4nBijyvLfTKXrghQGSm0bi1aW69uzfaGPk1yEOxNV24jSglSiN0095qb5TFnGfccC0SPB/KsQhvKViSl5JCAuYr7aVUgoB6vy3kfew4+TVgbD+YtFbjg0E5y/NOnN9acxhEntx8AZyYfYm/L5c8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747394752; c=relaxed/simple; bh=aEsNIF9y6JxcvOwyyzzXZ1H3HPtUSep+0f3agKGpmcE=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=nciB7KmLkuYvWKdeGkWCbDiNlildFOdD5S2Sb8Mmh7/K/Z4PW2ZbGTAylPSGJ8fe2YUg5mmbGn/mnlFr9BYbohwp8VXDPoNOcOpZLiNr0rZYuFMy5Mkn3OAyER4bSvIUe+TYW4g0kqC6/by4f6Pn709RWQDR4SRjjjrb1IC1vPA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=pAJEYftS; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="pAJEYftS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 98753C4CEE4; Fri, 16 May 2025 11:25:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1747394752; bh=aEsNIF9y6JxcvOwyyzzXZ1H3HPtUSep+0f3agKGpmcE=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=pAJEYftSqS3wkN3BRYgU3SIPkSLTPQNiSALKSkPtRAypqJ4ukWIB5If3C4d+RLXCd ehiy2COgUCbUcdzPaT6slmiIIe5sslmzE2TLRGT9dDbChRZ7AK+rJS5ekSscvIzuPu tJbUXmEfWnZywVf1+MCRmhD5zP9eMNJnFErqgTOSTseNgsvbwvgfbG0tP1pB9zh0MD hKFDqowhqAAizpbkxuHMD7fORZ/POBpbaTeIp7/TfbdWcSU5LwIXvuG+Pk90H6EPdT FxQyiWNShNZBgEuLitSC6C7MioiSjv6sv6wn8aREMWYwIMxhRvFDTnpFnWp4zhx6NP XpClbpocZ7aww== From: Christian Brauner Date: Fri, 16 May 2025 13:25:28 +0200 Subject: [PATCH v8 1/9] coredump: massage format_corename() Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20250516-work-coredump-socket-v8-1-664f3caf2516@kernel.org> References: <20250516-work-coredump-socket-v8-0-664f3caf2516@kernel.org> In-Reply-To: <20250516-work-coredump-socket-v8-0-664f3caf2516@kernel.org> To: linux-fsdevel@vger.kernel.org, Jann Horn , Daniel Borkmann , Kuniyuki Iwashima Cc: Eric Dumazet , Oleg Nesterov , "David S. Miller" , Alexander Viro , Daan De Meyer , David Rheinsberg , Jakub Kicinski , Jan Kara , Lennart Poettering , Luca Boccassi , Mike Yuan , Paolo Abeni , Simon Horman , =?utf-8?q?Zbigniew_J=C4=99drzejewski-Szmek?= , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-security-module@vger.kernel.org, Christian Brauner , Alexander Mikhalitsyn , Serge Hallyn X-Mailer: b4 0.15-dev-6f78e X-Developer-Signature: v=1; a=openpgp-sha256; l=4920; i=brauner@kernel.org; h=from:subject:message-id; bh=aEsNIF9y6JxcvOwyyzzXZ1H3HPtUSep+0f3agKGpmcE=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWSoK2zNll65uP+fdZW3UFZK/p59S8oP58Rbcn4XiLvP+ PS7maduRykLgxgXg6yYIotDu0m43HKeis1GmRowc1iZQIYwcHEKwERuBjIy7FjvxCGluG+Z5wan 3rA1kYHqrQ5TwgNdzsWnKxx4YbZFlJHh0Mwfd4QPzuY8MmOys0n/h8nCR9+e/v6vKNlHY86UlZ4 zOAA= X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 We're going to extend the coredump code in follow-up patches. Clean it up so we can do this more easily. Acked-by: Serge Hallyn Acked-by: Luca Boccassi Reviewed-by: Jann Horn Reviewed-by: Alexander Mikhalitsyn Signed-off-by: Christian Brauner --- fs/coredump.c | 46 +++++++++++++++++++++++++--------------------- 1 file changed, 25 insertions(+), 21 deletions(-) diff --git a/fs/coredump.c b/fs/coredump.c index d740a0411266..45725465c299 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -76,9 +76,15 @@ static char core_pattern[CORENAME_MAX_SIZE] =3D "core"; static int core_name_size =3D CORENAME_MAX_SIZE; unsigned int core_file_note_size_limit =3D CORE_FILE_NOTE_SIZE_DEFAULT; =20 +enum coredump_type_t { + COREDUMP_FILE =3D 1, + COREDUMP_PIPE =3D 2, +}; + struct core_name { char *corename; int used, size; + enum coredump_type_t core_type; }; =20 static int expand_corename(struct core_name *cn, int size) @@ -218,18 +224,21 @@ static int format_corename(struct core_name *cn, stru= ct coredump_params *cprm, { const struct cred *cred =3D current_cred(); const char *pat_ptr =3D core_pattern; - int ispipe =3D (*pat_ptr =3D=3D '|'); bool was_space =3D false; int pid_in_pattern =3D 0; int err =3D 0; =20 cn->used =3D 0; cn->corename =3D NULL; + if (*pat_ptr =3D=3D '|') + cn->core_type =3D COREDUMP_PIPE; + else + cn->core_type =3D COREDUMP_FILE; if (expand_corename(cn, core_name_size)) return -ENOMEM; cn->corename[0] =3D '\0'; =20 - if (ispipe) { + if (cn->core_type =3D=3D COREDUMP_PIPE) { int argvs =3D sizeof(core_pattern) / 2; (*argv) =3D kmalloc_array(argvs, sizeof(**argv), GFP_KERNEL); if (!(*argv)) @@ -247,7 +256,7 @@ static int format_corename(struct core_name *cn, struct= coredump_params *cprm, * Split on spaces before doing template expansion so that * %e and %E don't get split if they have spaces in them */ - if (ispipe) { + if (cn->core_type =3D=3D COREDUMP_PIPE) { if (isspace(*pat_ptr)) { if (cn->used !=3D 0) was_space =3D true; @@ -353,7 +362,7 @@ static int format_corename(struct core_name *cn, struct= coredump_params *cprm, * Installing a pidfd only makes sense if * we actually spawn a usermode helper. */ - if (!ispipe) + if (cn->core_type !=3D COREDUMP_PIPE) break; =20 /* @@ -384,12 +393,9 @@ static int format_corename(struct core_name *cn, struc= t coredump_params *cprm, * If core_pattern does not include a %p (as is the default) * and core_uses_pid is set, then .%pid will be appended to * the filename. Do not do this for piped commands. */ - if (!ispipe && !pid_in_pattern && core_uses_pid) { - err =3D cn_printf(cn, ".%d", task_tgid_vnr(current)); - if (err) - return err; - } - return ispipe; + if (cn->core_type =3D=3D COREDUMP_FILE && !pid_in_pattern && core_uses_pi= d) + return cn_printf(cn, ".%d", task_tgid_vnr(current)); + return 0; } =20 static int zap_process(struct signal_struct *signal, int exit_code) @@ -583,7 +589,6 @@ void do_coredump(const kernel_siginfo_t *siginfo) const struct cred *old_cred; struct cred *cred; int retval =3D 0; - int ispipe; size_t *argv =3D NULL; int argc =3D 0; /* require nonrelative corefile path and be extra careful */ @@ -632,19 +637,18 @@ void do_coredump(const kernel_siginfo_t *siginfo) =20 old_cred =3D override_creds(cred); =20 - ispipe =3D format_corename(&cn, &cprm, &argv, &argc); + retval =3D format_corename(&cn, &cprm, &argv, &argc); + if (retval < 0) { + coredump_report_failure("format_corename failed, aborting core"); + goto fail_unlock; + } =20 - if (ispipe) { + if (cn.core_type =3D=3D COREDUMP_PIPE) { int argi; int dump_count; char **helper_argv; struct subprocess_info *sub_info; =20 - if (ispipe < 0) { - coredump_report_failure("format_corename failed, aborting core"); - goto fail_unlock; - } - if (cprm.limit =3D=3D 1) { /* See umh_coredump_setup() which sets RLIMIT_CORE =3D 1. * @@ -695,7 +699,7 @@ void do_coredump(const kernel_siginfo_t *siginfo) coredump_report_failure("|%s pipe failed", cn.corename); goto close_fail; } - } else { + } else if (cn.core_type =3D=3D COREDUMP_FILE) { struct mnt_idmap *idmap; struct inode *inode; int open_flags =3D O_CREAT | O_WRONLY | O_NOFOLLOW | @@ -823,13 +827,13 @@ void do_coredump(const kernel_siginfo_t *siginfo) file_end_write(cprm.file); free_vma_snapshot(&cprm); } - if (ispipe && core_pipe_limit) + if ((cn.core_type =3D=3D COREDUMP_PIPE) && core_pipe_limit) wait_for_dump_helpers(cprm.file); close_fail: if (cprm.file) filp_close(cprm.file, NULL); fail_dropcount: - if (ispipe) + if (cn.core_type =3D=3D COREDUMP_PIPE) atomic_dec(&core_dump_count); fail_unlock: kfree(argv); --=20 2.47.2 From nobody Mon Dec 15 02:55:36 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 D6650205502; Fri, 16 May 2025 11:25:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747394758; cv=none; b=JxVVlv7lmTwzl4TAZjykCTvBRpf0L9g5Ogx6h9mp+UigIIx38RJL069S7fTX9c7E9FtG2/mRrlRgWJLHxqK6TI2XU5sp1dOA84UOAu4IGt31AHqE7vKoefvHEFJUD2a8bVN9+mWppOhWbSpVivPYXWfzH2AjUTBBetH/gCnSRAo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747394758; c=relaxed/simple; bh=ko2BjK77OT+gmmXf5cdOJrFqFr0W5DbZFPX/gNkIr84=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=E9iyBpl4dXiixk0RtYoTAzxVrUN8iWDjwyDioFgBskCdyTPbRNt5lXRtD8T7T2rXKVVQR6PV3NxFmFbIf58oeCH0qyzsjn4GXComewQuGg0V/TZ2qYdIDuj/Zbe9ZxksNKvTdb1EFyrVpaM4toUBNreYGCcvbduZDplSDrI+Q60= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Co7OiZ12; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Co7OiZ12" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B3EE6C4CEE4; Fri, 16 May 2025 11:25:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1747394757; bh=ko2BjK77OT+gmmXf5cdOJrFqFr0W5DbZFPX/gNkIr84=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=Co7OiZ126uEXurIc0JVM+7N6XOb1KpZg6YoZ2vvH2AFYesv5nfZ1PWdOwxZy7+MEq 85ncbEN8tkfDhzKRLo4Np1h5qckf6qT2XcH+KhCF+uYMBd4IT/fTFnUkKvUco44D8w js8zwm15qtVtx5Avb8w9f4/g/XciemlqgAlSPiFxekNYiUmu296CEaXLmTO5pNHEUt /Z12QGFkPmy9hOF28f5acw3t+PtfsyCYPzMPtF6lYarmjdojQE5saEz+RE1ozJqSF7 y+ciKXTKfCoK3NQT7cvHSgoM12DkLNwZ4PmEU7xzUUcELQMWvWaAcEG0g5AxXxtwsX 1OAHPHXjDRnJA== From: Christian Brauner Date: Fri, 16 May 2025 13:25:29 +0200 Subject: [PATCH v8 2/9] coredump: massage do_coredump() Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20250516-work-coredump-socket-v8-2-664f3caf2516@kernel.org> References: <20250516-work-coredump-socket-v8-0-664f3caf2516@kernel.org> In-Reply-To: <20250516-work-coredump-socket-v8-0-664f3caf2516@kernel.org> To: linux-fsdevel@vger.kernel.org, Jann Horn , Daniel Borkmann , Kuniyuki Iwashima Cc: Eric Dumazet , Oleg Nesterov , "David S. Miller" , Alexander Viro , Daan De Meyer , David Rheinsberg , Jakub Kicinski , Jan Kara , Lennart Poettering , Luca Boccassi , Mike Yuan , Paolo Abeni , Simon Horman , =?utf-8?q?Zbigniew_J=C4=99drzejewski-Szmek?= , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-security-module@vger.kernel.org, Christian Brauner , Alexander Mikhalitsyn X-Mailer: b4 0.15-dev-6f78e X-Developer-Signature: v=1; a=openpgp-sha256; l=5079; i=brauner@kernel.org; h=from:subject:message-id; bh=ko2BjK77OT+gmmXf5cdOJrFqFr0W5DbZFPX/gNkIr84=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWSoK2ydeeTLkos1zkeEH3DolMSIvV0SkrZ316cz2arKf y9cCNiv21HKwiDGxSArpsji0G4SLrecp2KzUaYGzBxWJpAhDFycAjCRT0qMDPfOh39cz/p841k7 qwlX3os3LbQJmbFx7znFzbyzdJl/vqlmZGhpdj83t/96xO7Ssx+/Jl0tlDnX+9v3/wSLfv5IpTN ptVwA X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 We're going to extend the coredump code in follow-up patches. Clean it up so we can do this more easily. Acked-by: Luca Boccassi Reviewed-by: Jann Horn Reviewed-by: Alexander Mikhalitsyn Signed-off-by: Christian Brauner --- fs/coredump.c | 122 +++++++++++++++++++++++++++++++-----------------------= ---- 1 file changed, 65 insertions(+), 57 deletions(-) diff --git a/fs/coredump.c b/fs/coredump.c index 45725465c299..47c811d32028 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -643,63 +643,8 @@ void do_coredump(const kernel_siginfo_t *siginfo) goto fail_unlock; } =20 - if (cn.core_type =3D=3D COREDUMP_PIPE) { - int argi; - int dump_count; - char **helper_argv; - struct subprocess_info *sub_info; - - if (cprm.limit =3D=3D 1) { - /* See umh_coredump_setup() which sets RLIMIT_CORE =3D 1. - * - * Normally core limits are irrelevant to pipes, since - * we're not writing to the file system, but we use - * cprm.limit of 1 here as a special value, this is a - * consistent way to catch recursive crashes. - * We can still crash if the core_pattern binary sets - * RLIM_CORE =3D !1, but it runs as root, and can do - * lots of stupid things. - * - * Note that we use task_tgid_vnr here to grab the pid - * of the process group leader. That way we get the - * right pid if a thread in a multi-threaded - * core_pattern process dies. - */ - coredump_report_failure("RLIMIT_CORE is set to 1, aborting core"); - goto fail_unlock; - } - cprm.limit =3D RLIM_INFINITY; - - dump_count =3D atomic_inc_return(&core_dump_count); - if (core_pipe_limit && (core_pipe_limit < dump_count)) { - coredump_report_failure("over core_pipe_limit, skipping core dump"); - goto fail_dropcount; - } - - helper_argv =3D kmalloc_array(argc + 1, sizeof(*helper_argv), - GFP_KERNEL); - if (!helper_argv) { - coredump_report_failure("%s failed to allocate memory", __func__); - goto fail_dropcount; - } - for (argi =3D 0; argi < argc; argi++) - helper_argv[argi] =3D cn.corename + argv[argi]; - helper_argv[argi] =3D NULL; - - retval =3D -ENOMEM; - sub_info =3D call_usermodehelper_setup(helper_argv[0], - helper_argv, NULL, GFP_KERNEL, - umh_coredump_setup, NULL, &cprm); - if (sub_info) - retval =3D call_usermodehelper_exec(sub_info, - UMH_WAIT_EXEC); - - kfree(helper_argv); - if (retval) { - coredump_report_failure("|%s pipe failed", cn.corename); - goto close_fail; - } - } else if (cn.core_type =3D=3D COREDUMP_FILE) { + switch (cn.core_type) { + case COREDUMP_FILE: { struct mnt_idmap *idmap; struct inode *inode; int open_flags =3D O_CREAT | O_WRONLY | O_NOFOLLOW | @@ -793,6 +738,69 @@ void do_coredump(const kernel_siginfo_t *siginfo) if (do_truncate(idmap, cprm.file->f_path.dentry, 0, 0, cprm.file)) goto close_fail; + break; + } + case COREDUMP_PIPE: { + int argi; + int dump_count; + char **helper_argv; + struct subprocess_info *sub_info; + + if (cprm.limit =3D=3D 1) { + /* See umh_coredump_setup() which sets RLIMIT_CORE =3D 1. + * + * Normally core limits are irrelevant to pipes, since + * we're not writing to the file system, but we use + * cprm.limit of 1 here as a special value, this is a + * consistent way to catch recursive crashes. + * We can still crash if the core_pattern binary sets + * RLIM_CORE =3D !1, but it runs as root, and can do + * lots of stupid things. + * + * Note that we use task_tgid_vnr here to grab the pid + * of the process group leader. That way we get the + * right pid if a thread in a multi-threaded + * core_pattern process dies. + */ + coredump_report_failure("RLIMIT_CORE is set to 1, aborting core"); + goto fail_unlock; + } + cprm.limit =3D RLIM_INFINITY; + + dump_count =3D atomic_inc_return(&core_dump_count); + if (core_pipe_limit && (core_pipe_limit < dump_count)) { + coredump_report_failure("over core_pipe_limit, skipping core dump"); + goto fail_dropcount; + } + + helper_argv =3D kmalloc_array(argc + 1, sizeof(*helper_argv), + GFP_KERNEL); + if (!helper_argv) { + coredump_report_failure("%s failed to allocate memory", __func__); + goto fail_dropcount; + } + for (argi =3D 0; argi < argc; argi++) + helper_argv[argi] =3D cn.corename + argv[argi]; + helper_argv[argi] =3D NULL; + + retval =3D -ENOMEM; + sub_info =3D call_usermodehelper_setup(helper_argv[0], + helper_argv, NULL, GFP_KERNEL, + umh_coredump_setup, NULL, &cprm); + if (sub_info) + retval =3D call_usermodehelper_exec(sub_info, + UMH_WAIT_EXEC); + + kfree(helper_argv); + if (retval) { + coredump_report_failure("|%s pipe failed", cn.corename); + goto close_fail; + } + break; + } + default: + WARN_ON_ONCE(true); + goto close_fail; } =20 /* get us an unshared descriptor table; almost always a no-op */ --=20 2.47.2 From nobody Mon Dec 15 02:55:36 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 05B3823816B; Fri, 16 May 2025 11:26:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747394763; cv=none; b=tssb/yS+ogko6X1qqAWwfcEYPWOZFR5/d69MnOlRj1zO2DXzVsLwwDuTb/fPWAFditG0TVzImq98zedDV/EVc7uF0B8h83jW/iq9cTjiTTrfQ1jR3Dd7TcAUqLNui/uPX9Z7QpcRDNBoOneK60yG69C0qL7WFjfEeJysn9nRidI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747394763; c=relaxed/simple; bh=So2gG7QcCwBeFlnjr1ntJgcFQt5U/NoPavduZCJOHsc=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=Xk0R4IpOx9hsSt5ywKIo7yOjKvsa0sMJhKUOs26j9AFb7BbKU6zbiUNQ1wve5mj+H7JKjvTM/A/4tt3zTS+gdylHpMemJ4eNPLWXL+HDvgjjkfudkdaBeCZs4Mj9YyuppR03k4yXj2cOrYoEs7FZ4+SRDXARkmOLkU5MMjY4nMM= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=E6AMSPQ/; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="E6AMSPQ/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BE2FAC4CEF1; Fri, 16 May 2025 11:25:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1747394762; bh=So2gG7QcCwBeFlnjr1ntJgcFQt5U/NoPavduZCJOHsc=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=E6AMSPQ/vB6VlIrTqQlpQr/nb3B+IReAJvy7OKGMKOiyNualnuZ15bqRd60MGCvo3 Mv0QsxsC5A/eIDFGjJkmyGwbhKTO3xDHFLEJb9b/uRMYdVuvTKGCcGxzHu3xMz5Chs NUyipLdZmOYK0EGs7uJaEwQIvUNR5X68nTr5RgYisQix3lZuFpP/uj489N/vuMv5QZ a3xAiyx8fDuBicIlzAwDTBN5BycXl2GfOsYmYcWL5Ntnlax2VkWnm32qkFUAROYV42 wh15nJfMW6VSB3+zDxuoYXRA/7sgAqAKAgviNnyD3oCi1BlR3Hmh0jWOOVHoIj2p8t wGQGhfKDD8IBg== From: Christian Brauner Date: Fri, 16 May 2025 13:25:30 +0200 Subject: [PATCH v8 3/9] coredump: reflow dump helpers a little Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20250516-work-coredump-socket-v8-3-664f3caf2516@kernel.org> References: <20250516-work-coredump-socket-v8-0-664f3caf2516@kernel.org> In-Reply-To: <20250516-work-coredump-socket-v8-0-664f3caf2516@kernel.org> To: linux-fsdevel@vger.kernel.org, Jann Horn , Daniel Borkmann , Kuniyuki Iwashima Cc: Eric Dumazet , Oleg Nesterov , "David S. Miller" , Alexander Viro , Daan De Meyer , David Rheinsberg , Jakub Kicinski , Jan Kara , Lennart Poettering , Luca Boccassi , Mike Yuan , Paolo Abeni , Simon Horman , =?utf-8?q?Zbigniew_J=C4=99drzejewski-Szmek?= , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-security-module@vger.kernel.org, Christian Brauner , Alexander Mikhalitsyn X-Mailer: b4 0.15-dev-6f78e X-Developer-Signature: v=1; a=openpgp-sha256; l=1646; i=brauner@kernel.org; h=from:subject:message-id; bh=So2gG7QcCwBeFlnjr1ntJgcFQt5U/NoPavduZCJOHsc=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWSoK2xN95rx8qYg4z9BXb9kH20LYesbUj+nPey1XOlg+ q6n6JF3RykLgxgXg6yYIotDu0m43HKeis1GmRowc1iZQIYwcHEKwEQs1Bj+F3/+V3h7T1xxo7D7 hxNsk16dyPPmKvzl5bBTtyhzvds8NobfLGc0fy3tS+94La59YMX3yCW5nOuq+04UJsmz3/qtban FDQA= X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 They look rather messy right now. Acked-by: Luca Boccassi Reviewed-by: Jann Horn Reviewed-by: Alexander Mikhalitsyn Signed-off-by: Christian Brauner --- fs/coredump.c | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-) diff --git a/fs/coredump.c b/fs/coredump.c index 47c811d32028..4b9ea455a59c 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -864,10 +864,9 @@ static int __dump_emit(struct coredump_params *cprm, c= onst void *addr, int nr) struct file *file =3D cprm->file; loff_t pos =3D file->f_pos; ssize_t n; + if (cprm->written + nr > cprm->limit) return 0; - - if (dump_interrupted()) return 0; n =3D __kernel_write(file, addr, nr, &pos); @@ -884,20 +883,21 @@ static int __dump_skip(struct coredump_params *cprm, = size_t nr) { static char zeroes[PAGE_SIZE]; struct file *file =3D cprm->file; + if (file->f_mode & FMODE_LSEEK) { - if (dump_interrupted() || - vfs_llseek(file, nr, SEEK_CUR) < 0) + if (dump_interrupted() || vfs_llseek(file, nr, SEEK_CUR) < 0) return 0; cprm->pos +=3D nr; return 1; - } else { - while (nr > PAGE_SIZE) { - if (!__dump_emit(cprm, zeroes, PAGE_SIZE)) - return 0; - nr -=3D PAGE_SIZE; - } - return __dump_emit(cprm, zeroes, nr); } + + while (nr > PAGE_SIZE) { + if (!__dump_emit(cprm, zeroes, PAGE_SIZE)) + return 0; + nr -=3D PAGE_SIZE; + } + + return __dump_emit(cprm, zeroes, nr); } =20 int dump_emit(struct coredump_params *cprm, const void *addr, int nr) --=20 2.47.2 From nobody Mon Dec 15 02:55:36 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 EE4C923814C; Fri, 16 May 2025 11:26:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747394768; cv=none; b=Mena9B/p9UJHncIUbIJmIIs29LzGg6+qG3MtbVnfDo2V2DdHBqIusKw8e9ZEAvA3ywyinb9JKwSR64epsWsEzT+ltBIGLROoofsOhCvIuArfoCSZe+7l+OkZRu/BC5PgTnZwqYd2TP76wAsWa7nxO+N4k2ntEQmG1rGMOT8pohw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747394768; c=relaxed/simple; bh=I0FLSau3CcCCIaWzaWkXLPHR7CUrMZvzVdgOX8/naXU=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=TNlZGpz2QJ2Q/k8dtSXT8IqlY3JNcTkQ6nKpmI9XQAeTDoNmpfBu5Rwc8gG+dQ5SIfSc1mGTPEC+jPe3zPSWbXia/Q1jygbrfuE46Nqn2IePJ0GsLfAqVHvDYjA9Gyg8iHeXjdgExKw7jZAbaBcWLgB82HxljfBwpHyiCeYpp8I= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ImVKPdg2; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ImVKPdg2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E8D55C4CEE4; Fri, 16 May 2025 11:26:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1747394767; bh=I0FLSau3CcCCIaWzaWkXLPHR7CUrMZvzVdgOX8/naXU=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=ImVKPdg2BgZHX2ggX8sYb7m/N1QjScSgsIPj4KH8+mxZnyDnSfZbbIcGPfTjwFdcx qJQ+GHfGK2fgmZ+sh4WygLnnJHUEswbrbQSfY1GBYVHxsMZ7zlkkHB+KftVt+qZriI HRwMVcZ38YErH2l2IaNQ2yTPz/UN1pw6KYaVGwS64j2bknAyt1Qy2JNJ4tkPpOm7os bOan9s9wZ77BqdP2VF9q0SJD3kfwnLoYMZaV7NmOtpYfVWhJ9RtFaEGHG5kVbDFXFS iQuXI4yR62+zhiwz72o0bibp/wqiQDzSOxuas2ITfeZoxA7wwXPbZOSCiiWg2k+Fiu SgvuBnR2XR1Dg== From: Christian Brauner Date: Fri, 16 May 2025 13:25:31 +0200 Subject: [PATCH v8 4/9] coredump: add coredump socket Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20250516-work-coredump-socket-v8-4-664f3caf2516@kernel.org> References: <20250516-work-coredump-socket-v8-0-664f3caf2516@kernel.org> In-Reply-To: <20250516-work-coredump-socket-v8-0-664f3caf2516@kernel.org> To: linux-fsdevel@vger.kernel.org, Jann Horn , Daniel Borkmann , Kuniyuki Iwashima Cc: Eric Dumazet , Oleg Nesterov , "David S. Miller" , Alexander Viro , Daan De Meyer , David Rheinsberg , Jakub Kicinski , Jan Kara , Lennart Poettering , Luca Boccassi , Mike Yuan , Paolo Abeni , Simon Horman , =?utf-8?q?Zbigniew_J=C4=99drzejewski-Szmek?= , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-security-module@vger.kernel.org, Christian Brauner , Alexander Mikhalitsyn X-Mailer: b4 0.15-dev-6f78e X-Developer-Signature: v=1; a=openpgp-sha256; l=14302; i=brauner@kernel.org; h=from:subject:message-id; bh=I0FLSau3CcCCIaWzaWkXLPHR7CUrMZvzVdgOX8/naXU=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWSoK2ztmKbLLP+AS9xwgcj5kk9TFUonhQVmdUzf+6Ty8 EJtR4Y/HaUsDGJcDLJiiiwO7Sbhcst5KjYbZWrAzGFlAhnCwMUpABMxeMrwhytQlou12m3jwX9G DEcrG++ovd00vXTViuKEqljx+idnHBgZ9id5tV82VHJXtGvvUbxw7aFuwQWuCa3fYyLdE29snsT MAgA= X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 Coredumping currently supports two modes: (1) Dumping directly into a file somewhere on the filesystem. (2) Dumping into a pipe connected to a usermode helper process spawned as a child of the system_unbound_wq or kthreadd. For simplicity I'm mostly ignoring (1). There's probably still some users of (1) out there but processing coredumps in this way can be considered adventurous especially in the face of set*id binaries. The most common option should be (2) by now. It works by allowing userspace to put a string into /proc/sys/kernel/core_pattern like: |/usr/lib/systemd/systemd-coredump %P %u %g %s %t %c %h The "|" at the beginning indicates to the kernel that a pipe must be used. The path following the pipe indicator is a path to a binary that will be spawned as a usermode helper process. Any additional parameters pass information about the task that is generating the coredump to the binary that processes the coredump. In the example core_pattern shown above systemd-coredump is spawned as a usermode helper. There's various conceptual consequences of this (non-exhaustive list): - systemd-coredump is spawned with file descriptor number 0 (stdin) connected to the read-end of the pipe. All other file descriptors are closed. That specifically includes 1 (stdout) and 2 (stderr). This has already caused bugs because userspace assumed that this cannot happen (Whether or not this is a sane assumption is irrelevant.). - systemd-coredump will be spawned as a child of system_unbound_wq. So it is not a child of any userspace process and specifically not a child of PID 1. It cannot be waited upon and is in a weird hybrid upcall which are difficult for userspace to control correctly. - systemd-coredump is spawned with full kernel privileges. This necessitates all kinds of weird privilege dropping excercises in userspace to make this safe. - A new usermode helper has to be spawned for each crashing process. This series adds a new mode: (3) Dumping into an AF_UNIX socket. Userspace can set /proc/sys/kernel/core_pattern to: @/path/to/coredump.socket The "@" at the beginning indicates to the kernel that an AF_UNIX coredump socket will be used to process coredumps. The coredump socket must be located in the initial mount namespace. When a task coredumps it opens a client socket in the initial network namespace and connects to the coredump socket. - The coredump server uses SO_PEERPIDFD to get a stable handle on the connected crashing task. The retrieved pidfd will provide a stable reference even if the crashing task gets SIGKILLed while generating the coredump. - By setting core_pipe_limit non-zero userspace can guarantee that the crashing task cannot be reaped behind it's back and thus process all necessary information in /proc/. The SO_PEERPIDFD can be used to detect whether /proc/ still refers to the same process. The core_pipe_limit isn't used to rate-limit connections to the socket. This can simply be done via AF_UNIX sockets directly. - The pidfd for the crashing task will grow new information how the task coredumps. - The coredump server should mark itself as non-dumpable. - A container coredump server in a separate network namespace can simply bind to another well-know address and systemd-coredump fowards coredumps to the container. - Coredumps could in the future also be handled via per-user/session coredump servers that run only with that users privileges. The coredump server listens on the coredump socket and accepts a new coredump connection. It then retrieves SO_PEERPIDFD for the client, inspects uid/gid and hands the accepted client to the users own coredump handler which runs with the users privileges only (It must of coure pay close attention to not forward crashing suid binaries.). The new coredump socket will allow userspace to not have to rely on usermode helpers for processing coredumps and provides a safer way to handle them instead of relying on super privileged coredumping helpers that have and continue to cause significant CVEs. This will also be significantly more lightweight since no fork()+exec() for the usermodehelper is required for each crashing process. The coredump server in userspace can e.g., just keep a worker pool. Acked-by: Luca Boccassi Reviewed-by: Kuniyuki Iwashima Reviewed-by: Alexander Mikhalitsyn Signed-off-by: Christian Brauner Reviewed-by: Jann Horn Reviewed-by: Paul Moore --- fs/coredump.c | 118 ++++++++++++++++++++++++++++++++++++++++++++++++= ++-- include/linux/net.h | 1 + net/unix/af_unix.c | 54 ++++++++++++++++++------ 3 files changed, 156 insertions(+), 17 deletions(-) diff --git a/fs/coredump.c b/fs/coredump.c index 4b9ea455a59c..6eaf2ff89af8 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -44,7 +44,11 @@ #include #include #include +#include +#include +#include #include +#include =20 #include #include @@ -79,6 +83,7 @@ unsigned int core_file_note_size_limit =3D CORE_FILE_NOTE= _SIZE_DEFAULT; enum coredump_type_t { COREDUMP_FILE =3D 1, COREDUMP_PIPE =3D 2, + COREDUMP_SOCK =3D 3, }; =20 struct core_name { @@ -232,13 +237,16 @@ static int format_corename(struct core_name *cn, stru= ct coredump_params *cprm, cn->corename =3D NULL; if (*pat_ptr =3D=3D '|') cn->core_type =3D COREDUMP_PIPE; + else if (*pat_ptr =3D=3D '@') + cn->core_type =3D COREDUMP_SOCK; else cn->core_type =3D COREDUMP_FILE; if (expand_corename(cn, core_name_size)) return -ENOMEM; cn->corename[0] =3D '\0'; =20 - if (cn->core_type =3D=3D COREDUMP_PIPE) { + switch (cn->core_type) { + case COREDUMP_PIPE: { int argvs =3D sizeof(core_pattern) / 2; (*argv) =3D kmalloc_array(argvs, sizeof(**argv), GFP_KERNEL); if (!(*argv)) @@ -247,6 +255,36 @@ static int format_corename(struct core_name *cn, struc= t coredump_params *cprm, ++pat_ptr; if (!(*pat_ptr)) return -ENOMEM; + break; + } + case COREDUMP_SOCK: { + /* skip the @ */ + pat_ptr++; + if (!(*pat_ptr)) + return -ENOMEM; + + err =3D cn_printf(cn, "%s", pat_ptr); + if (err) + return err; + + /* Require absolute paths. */ + if (cn->corename[0] !=3D '/') + return -EINVAL; + + /* + * Currently no need to parse any other options. + * Relevant information can be retrieved from the peer + * pidfd retrievable via SO_PEERPIDFD by the receiver or + * via /proc/, using the SO_PEERPIDFD to guard + * against pid recycling when opening /proc/. + */ + return 0; + } + case COREDUMP_FILE: + break; + default: + WARN_ON_ONCE(true); + return -EINVAL; } =20 /* Repeat as long as we have more pattern to process and more output @@ -395,6 +433,7 @@ static int format_corename(struct core_name *cn, struct= coredump_params *cprm, * the filename. Do not do this for piped commands. */ if (cn->core_type =3D=3D COREDUMP_FILE && !pid_in_pattern && core_uses_pi= d) return cn_printf(cn, ".%d", task_tgid_vnr(current)); + return 0; } =20 @@ -798,6 +837,53 @@ void do_coredump(const kernel_siginfo_t *siginfo) } break; } + case COREDUMP_SOCK: { +#ifdef CONFIG_UNIX + struct file *file __free(fput) =3D NULL; + struct sockaddr_un addr =3D { + .sun_family =3D AF_UNIX, + }; + ssize_t addr_len; + struct socket *socket; + + addr_len =3D strscpy(addr.sun_path, cn.corename); + if (addr_len < 0) + goto close_fail; + addr_len +=3D offsetof(struct sockaddr_un, sun_path) + 1; + + /* + * It is possible that the userspace process which is + * supposed to handle the coredump and is listening on + * the AF_UNIX socket coredumps. Userspace should just + * mark itself non dumpable. + */ + + retval =3D sock_create_kern(&init_net, AF_UNIX, SOCK_STREAM, 0, &socket); + if (retval < 0) + goto close_fail; + + file =3D sock_alloc_file(socket, 0, NULL); + if (IS_ERR(file)) + goto close_fail; + + retval =3D kernel_connect(socket, (struct sockaddr *)(&addr), + addr_len, O_NONBLOCK | SOCK_COREDUMP); + if (retval) { + if (retval =3D=3D -EAGAIN) + coredump_report_failure("Coredump socket %s receive queue full", addr.= sun_path); + else + coredump_report_failure("Coredump socket connection %s failed %d", add= r.sun_path, retval); + goto close_fail; + } + + cprm.limit =3D RLIM_INFINITY; + cprm.file =3D no_free_ptr(file); +#else + coredump_report_failure("Core dump socket support %s disabled", cn.coren= ame); + goto close_fail; +#endif + break; + } default: WARN_ON_ONCE(true); goto close_fail; @@ -835,8 +921,32 @@ void do_coredump(const kernel_siginfo_t *siginfo) file_end_write(cprm.file); free_vma_snapshot(&cprm); } - if ((cn.core_type =3D=3D COREDUMP_PIPE) && core_pipe_limit) - wait_for_dump_helpers(cprm.file); + + /* + * When core_pipe_limit is set we wait for the coredump server + * or usermodehelper to finish before exiting so it can e.g., + * inspect /proc/. + */ + if (core_pipe_limit) { + switch (cn.core_type) { + case COREDUMP_PIPE: + wait_for_dump_helpers(cprm.file); + break; + case COREDUMP_SOCK: { + /* + * We use a simple read to wait for the coredump + * processing to finish. Either the socket is + * closed or we get sent unexpected data. In + * both cases, we're done. + */ + __kernel_read(cprm.file, &(char){ 0 }, 1, NULL); + break; + } + default: + break; + } + } + close_fail: if (cprm.file) filp_close(cprm.file, NULL); @@ -1066,7 +1176,7 @@ EXPORT_SYMBOL(dump_align); void validate_coredump_safety(void) { if (suid_dumpable =3D=3D SUID_DUMP_ROOT && - core_pattern[0] !=3D '/' && core_pattern[0] !=3D '|') { + core_pattern[0] !=3D '/' && core_pattern[0] !=3D '|' && core_pattern[= 0] !=3D '@') { =20 coredump_report_failure("Unsafe core_pattern used with fs.suid_dumpable= =3D2: " "pipe handler or fully qualified core dump path required. " diff --git a/include/linux/net.h b/include/linux/net.h index 0ff950eecc6b..139c85d0f2ea 100644 --- a/include/linux/net.h +++ b/include/linux/net.h @@ -81,6 +81,7 @@ enum sock_type { #ifndef SOCK_NONBLOCK #define SOCK_NONBLOCK O_NONBLOCK #endif +#define SOCK_COREDUMP O_NOCTTY =20 #endif /* ARCH_HAS_SOCKET_TYPES */ =20 diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 472f8aa9ea15..59a64b2ced6e 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -85,10 +85,13 @@ #include #include #include +#include #include #include #include #include +#include +#include #include #include #include @@ -100,7 +103,6 @@ #include #include #include -#include #include #include #include @@ -1146,7 +1148,7 @@ static int unix_release(struct socket *sock) } =20 static struct sock *unix_find_bsd(struct sockaddr_un *sunaddr, int addr_le= n, - int type) + int type, int flags) { struct inode *inode; struct path path; @@ -1154,13 +1156,39 @@ static struct sock *unix_find_bsd(struct sockaddr_u= n *sunaddr, int addr_len, int err; =20 unix_mkname_bsd(sunaddr, addr_len); - err =3D kern_path(sunaddr->sun_path, LOOKUP_FOLLOW, &path); - if (err) - goto fail; =20 - err =3D path_permission(&path, MAY_WRITE); - if (err) - goto path_put; + if (flags & SOCK_COREDUMP) { + const struct cred *cred; + struct cred *kcred; + struct path root; + + kcred =3D prepare_kernel_cred(&init_task); + if (!kcred) { + err =3D -ENOMEM; + goto fail; + } + + task_lock(&init_task); + get_fs_root(init_task.fs, &root); + task_unlock(&init_task); + + cred =3D override_creds(kcred); + err =3D vfs_path_lookup(root.dentry, root.mnt, sunaddr->sun_path, + LOOKUP_BENEATH | LOOKUP_NO_SYMLINKS | + LOOKUP_NO_MAGICLINKS, &path); + put_cred(revert_creds(cred)); + path_put(&root); + if (err) + goto fail; + } else { + err =3D kern_path(sunaddr->sun_path, LOOKUP_FOLLOW, &path); + if (err) + goto fail; + + err =3D path_permission(&path, MAY_WRITE); + if (err) + goto path_put; + } =20 err =3D -ECONNREFUSED; inode =3D d_backing_inode(path.dentry); @@ -1210,12 +1238,12 @@ static struct sock *unix_find_abstract(struct net *= net, =20 static struct sock *unix_find_other(struct net *net, struct sockaddr_un *sunaddr, - int addr_len, int type) + int addr_len, int type, int flags) { struct sock *sk; =20 if (sunaddr->sun_path[0]) - sk =3D unix_find_bsd(sunaddr, addr_len, type); + sk =3D unix_find_bsd(sunaddr, addr_len, type, flags); else sk =3D unix_find_abstract(net, sunaddr, addr_len, type); =20 @@ -1473,7 +1501,7 @@ static int unix_dgram_connect(struct socket *sock, st= ruct sockaddr *addr, } =20 restart: - other =3D unix_find_other(sock_net(sk), sunaddr, alen, sock->type); + other =3D unix_find_other(sock_net(sk), sunaddr, alen, sock->type, 0); if (IS_ERR(other)) { err =3D PTR_ERR(other); goto out; @@ -1620,7 +1648,7 @@ static int unix_stream_connect(struct socket *sock, s= truct sockaddr *uaddr, =20 restart: /* Find listening sock. */ - other =3D unix_find_other(net, sunaddr, addr_len, sk->sk_type); + other =3D unix_find_other(net, sunaddr, addr_len, sk->sk_type, flags); if (IS_ERR(other)) { err =3D PTR_ERR(other); goto out_free_skb; @@ -2089,7 +2117,7 @@ static int unix_dgram_sendmsg(struct socket *sock, st= ruct msghdr *msg, if (msg->msg_namelen) { lookup: other =3D unix_find_other(sock_net(sk), msg->msg_name, - msg->msg_namelen, sk->sk_type); + msg->msg_namelen, sk->sk_type, 0); if (IS_ERR(other)) { err =3D PTR_ERR(other); goto out_free; --=20 2.47.2 From nobody Mon Dec 15 02:55:36 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 0E9F824166E; Fri, 16 May 2025 11:26:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747394773; cv=none; b=p0CaV+Iyx3S/etQRjsuQomtfzF7dJgkCa/sjDZ9shATDMnTOWMZx3i991gBVhDc8AlKrMLR7xR4g9w9MwUvjpD9w6uwq0vcCsNNtXcW/3OXocJFo6O8gAf7jhYlHbBumNkd87/f9t6Yq8+jV9tq+7Gc1vfoXzKQbwxcHo29WppA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747394773; c=relaxed/simple; bh=lBq5fYSvXf+MUseDlW1solvXpXQVzOG148v6Vygqtuk=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=YSSvU6ubYFXeNhjDU5/w987c5IBFBM3OrDkc04wThWgGfHGhwO+TeBfetiWVVg5RaplvOjSXrU4imJJis62DLldi+OzQhjb2w/K8s9rvBohkciSq67jfXLRnrjifqtwQh82hYq3WAYZIsVOqJkiiZmNiQWdaIPMh61dowiXn/90= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ZHYq3n6K; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ZHYq3n6K" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DED7AC4CEEF; Fri, 16 May 2025 11:26:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1747394772; bh=lBq5fYSvXf+MUseDlW1solvXpXQVzOG148v6Vygqtuk=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=ZHYq3n6KxJpCo/J+fIsddX1zWKvl3pCFecvBstZBJUARnmoGkmlB6urJqK+mlsTPI 5eEJ5t4CdDwcdOaLXDlg6tQpJoNmuw/CA6n4O0uHRmbUdjX6RCXBnp2n99CTZnRJay HSWhu4kVUjWCR5sVKno43FMgqR6MEgayJCiyuYVYWs1MVMpxeJZOanyYuDCjbz8lTF 9FeFmjVK8Yu4HMStCCPlfUJDBqHmorw3CKaaM5QpQU/fN1BE5Ct4kzpo/Zq65qKx1h jgS9mUH5alpWD+mH2A/5ZzIljgfGH4iH6aPDy/a+iEyWXAWuJVu9tcI+2nu4ZpwHBX JmX58ZqoGO0ug== From: Christian Brauner Date: Fri, 16 May 2025 13:25:32 +0200 Subject: [PATCH v8 5/9] pidfs, coredump: add PIDFD_INFO_COREDUMP Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20250516-work-coredump-socket-v8-5-664f3caf2516@kernel.org> References: <20250516-work-coredump-socket-v8-0-664f3caf2516@kernel.org> In-Reply-To: <20250516-work-coredump-socket-v8-0-664f3caf2516@kernel.org> To: linux-fsdevel@vger.kernel.org, Jann Horn , Daniel Borkmann , Kuniyuki Iwashima Cc: Eric Dumazet , Oleg Nesterov , "David S. Miller" , Alexander Viro , Daan De Meyer , David Rheinsberg , Jakub Kicinski , Jan Kara , Lennart Poettering , Luca Boccassi , Mike Yuan , Paolo Abeni , Simon Horman , =?utf-8?q?Zbigniew_J=C4=99drzejewski-Szmek?= , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-security-module@vger.kernel.org, Christian Brauner , Alexander Mikhalitsyn X-Mailer: b4 0.15-dev-6f78e X-Developer-Signature: v=1; a=openpgp-sha256; l=8340; i=brauner@kernel.org; h=from:subject:message-id; bh=lBq5fYSvXf+MUseDlW1solvXpXQVzOG148v6Vygqtuk=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWSoK2y9ohYvpqD+9dPs/ycXnH+fu8fuukCl5g/tSQd1H 1asKHRj6ChlYRDjYpAVU2RxaDcJl1vOU7HZKFMDZg4rE8gQBi5OAZjInlRGhovircIhPhOUj1g3 hD67YT6nLe3gWXuvc/Ldsp6pF3Rb7zAyXLVp71v4TcE/xuLHg9j1qSq5FxZXBTted64oa562k9W SEwA= X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 Extend the PIDFD_INFO_COREDUMP ioctl() with the new PIDFD_INFO_COREDUMP mask flag. This adds the @coredump_mask field to struct pidfd_info. When a task coredumps the kernel will provide the following information to userspace in @coredump_mask: * PIDFD_COREDUMPED is raised if the task did actually coredump. * PIDFD_COREDUMP_SKIP is raised if the task skipped coredumping (e.g., undumpable). * PIDFD_COREDUMP_USER is raised if this is a regular coredump and doesn't need special care by the coredump server. * PIDFD_COREDUMP_ROOT is raised if the generated coredump should be treated as sensitive and the coredump server should restrict to the generated coredump to sufficiently privileged users. The kernel guarantees that by the time the connection is made the all PIDFD_INFO_COREDUMP info is available. Acked-by: Luca Boccassi Reviewed-by: Alexander Mikhalitsyn Signed-off-by: Christian Brauner Reviewed-by: Jann Horn --- fs/coredump.c | 31 ++++++++++++++++++++++++++ fs/pidfs.c | 55 ++++++++++++++++++++++++++++++++++++++++++= ++++ include/linux/pidfs.h | 5 +++++ include/uapi/linux/pidfd.h | 16 ++++++++++++++ 4 files changed, 107 insertions(+) diff --git a/fs/coredump.c b/fs/coredump.c index 6eaf2ff89af8..48064b1d6305 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -46,7 +46,9 @@ #include #include #include +#include #include +#include #include #include =20 @@ -590,6 +592,8 @@ static int umh_coredump_setup(struct subprocess_info *i= nfo, struct cred *new) if (IS_ERR(pidfs_file)) return PTR_ERR(pidfs_file); =20 + pidfs_coredump(cp); + /* * Usermode helpers are childen of either * system_unbound_wq or of kthreadd. So we know that @@ -866,8 +870,31 @@ void do_coredump(const kernel_siginfo_t *siginfo) if (IS_ERR(file)) goto close_fail; =20 + /* + * Set the thread-group leader pid which is used for the + * peer credentials during connect() below. Then + * immediately register it in pidfs... + */ + cprm.pid =3D task_tgid(current); + retval =3D pidfs_register_pid(cprm.pid); + if (retval) + goto close_fail; + + /* + * ... and set the coredump information so userspace + * has it available after connect()... + */ + pidfs_coredump(&cprm); + retval =3D kernel_connect(socket, (struct sockaddr *)(&addr), addr_len, O_NONBLOCK | SOCK_COREDUMP); + + /* + * ... Make sure to only put our reference after connect() took + * its own reference keeping the pidfs entry alive ... + */ + pidfs_put_pid(cprm.pid); + if (retval) { if (retval =3D=3D -EAGAIN) coredump_report_failure("Coredump socket %s receive queue full", addr.= sun_path); @@ -876,6 +903,10 @@ void do_coredump(const kernel_siginfo_t *siginfo) goto close_fail; } =20 + /* ... and validate that @sk_peer_pid matches @cprm.pid. */ + if (WARN_ON_ONCE(unix_peer(socket->sk)->sk_peer_pid !=3D cprm.pid)) + goto close_fail; + cprm.limit =3D RLIM_INFINITY; cprm.file =3D no_free_ptr(file); #else diff --git a/fs/pidfs.c b/fs/pidfs.c index 3b39e471840b..c0069fd52dd4 100644 --- a/fs/pidfs.c +++ b/fs/pidfs.c @@ -20,6 +20,7 @@ #include #include #include +#include =20 #include "internal.h" #include "mount.h" @@ -33,6 +34,7 @@ static struct kmem_cache *pidfs_cachep __ro_after_init; struct pidfs_exit_info { __u64 cgroupid; __s32 exit_code; + __u32 coredump_mask; }; =20 struct pidfs_inode { @@ -240,6 +242,22 @@ static inline bool pid_in_current_pidns(const struct p= id *pid) return false; } =20 +static __u32 pidfs_coredump_mask(unsigned long mm_flags) +{ + switch (__get_dumpable(mm_flags)) { + case SUID_DUMP_USER: + return PIDFD_COREDUMP_USER; + case SUID_DUMP_ROOT: + return PIDFD_COREDUMP_ROOT; + case SUID_DUMP_DISABLE: + return PIDFD_COREDUMP_SKIP; + default: + WARN_ON_ONCE(true); + } + + return 0; +} + static long pidfd_info(struct file *file, unsigned int cmd, unsigned long = arg) { struct pidfd_info __user *uinfo =3D (struct pidfd_info __user *)arg; @@ -280,6 +298,11 @@ static long pidfd_info(struct file *file, unsigned int= cmd, unsigned long arg) } } =20 + if (mask & PIDFD_INFO_COREDUMP) { + kinfo.mask |=3D PIDFD_INFO_COREDUMP; + kinfo.coredump_mask =3D READ_ONCE(pidfs_i(inode)->__pei.coredump_mask); + } + task =3D get_pid_task(pid, PIDTYPE_PID); if (!task) { /* @@ -296,6 +319,13 @@ static long pidfd_info(struct file *file, unsigned int= cmd, unsigned long arg) if (!c) return -ESRCH; =20 + if (!(kinfo.mask & PIDFD_INFO_COREDUMP)) { + task_lock(task); + if (task->mm) + kinfo.coredump_mask =3D pidfs_coredump_mask(task->mm->flags); + task_unlock(task); + } + /* Unconditionally return identifiers and credentials, the rest only on r= equest */ =20 user_ns =3D current_user_ns(); @@ -559,6 +589,31 @@ void pidfs_exit(struct task_struct *tsk) } } =20 +#ifdef CONFIG_COREDUMP +void pidfs_coredump(const struct coredump_params *cprm) +{ + struct pid *pid =3D cprm->pid; + struct pidfs_exit_info *exit_info; + struct dentry *dentry; + struct inode *inode; + __u32 coredump_mask =3D 0; + + dentry =3D pid->stashed; + if (WARN_ON_ONCE(!dentry)) + return; + + inode =3D d_inode(dentry); + exit_info =3D &pidfs_i(inode)->__pei; + /* Note how we were coredumped. */ + coredump_mask =3D pidfs_coredump_mask(cprm->mm_flags); + /* Note that we actually did coredump. */ + coredump_mask |=3D PIDFD_COREDUMPED; + /* If coredumping is set to skip we should never end up here. */ + VFS_WARN_ON_ONCE(coredump_mask & PIDFD_COREDUMP_SKIP); + smp_store_release(&exit_info->coredump_mask, coredump_mask); +} +#endif + static struct vfsmount *pidfs_mnt __ro_after_init; =20 /* diff --git a/include/linux/pidfs.h b/include/linux/pidfs.h index 2676890c4d0d..77e7db194914 100644 --- a/include/linux/pidfs.h +++ b/include/linux/pidfs.h @@ -2,11 +2,16 @@ #ifndef _LINUX_PID_FS_H #define _LINUX_PID_FS_H =20 +struct coredump_params; + struct file *pidfs_alloc_file(struct pid *pid, unsigned int flags); void __init pidfs_init(void); void pidfs_add_pid(struct pid *pid); void pidfs_remove_pid(struct pid *pid); void pidfs_exit(struct task_struct *tsk); +#ifdef CONFIG_COREDUMP +void pidfs_coredump(const struct coredump_params *cprm); +#endif extern const struct dentry_operations pidfs_dentry_operations; int pidfs_register_pid(struct pid *pid); void pidfs_get_pid(struct pid *pid); diff --git a/include/uapi/linux/pidfd.h b/include/uapi/linux/pidfd.h index 8c1511edd0e9..c27a4e238e4b 100644 --- a/include/uapi/linux/pidfd.h +++ b/include/uapi/linux/pidfd.h @@ -25,9 +25,23 @@ #define PIDFD_INFO_CREDS (1UL << 1) /* Always returned, even if not reque= sted */ #define PIDFD_INFO_CGROUPID (1UL << 2) /* Always returned if available, e= ven if not requested */ #define PIDFD_INFO_EXIT (1UL << 3) /* Only returned if requested. */ +#define PIDFD_INFO_COREDUMP (1UL << 4) /* Only returned if requested. */ =20 #define PIDFD_INFO_SIZE_VER0 64 /* sizeof first published struct */ =20 +/* + * Values for @coredump_mask in pidfd_info. + * Only valid if PIDFD_INFO_COREDUMP is set in @mask. + * + * Note, the @PIDFD_COREDUMP_ROOT flag indicates that the generated + * coredump should be treated as sensitive and access should only be + * granted to privileged users. + */ +#define PIDFD_COREDUMPED (1U << 0) /* Did crash and... */ +#define PIDFD_COREDUMP_SKIP (1U << 1) /* coredumping generation was skippe= d. */ +#define PIDFD_COREDUMP_USER (1U << 2) /* coredump was done as the user. */ +#define PIDFD_COREDUMP_ROOT (1U << 3) /* coredump was done as root. */ + /* * The concept of process and threads in userland and the kernel is a conf= using * one - within the kernel every thread is a 'task' with its own individua= l PID, @@ -92,6 +106,8 @@ struct pidfd_info { __u32 fsuid; __u32 fsgid; __s32 exit_code; + __u32 coredump_mask; + __u32 __spare1; }; =20 #define PIDFS_IOCTL_MAGIC 0xFF --=20 2.47.2 From nobody Mon Dec 15 02:55:36 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 4DE8A239E6C; Fri, 16 May 2025 11:26:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747394778; cv=none; b=R228hxsp7EamMIyUDzLTYB8inImv/IdsaTLaA3TBTLXl98c9hoerie4lXmLqeN3Giz2fkLmP5ks2zoHXtkdBOOcO6zXF/rhrguIlFcxTYpnH19tCpmugPqZ/ES2F9NOO12M50J0umH/7HDL1mRks8KL4XPUOxlNHaDtp3PBb8bw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747394778; c=relaxed/simple; bh=Ii80ZxJgXHUTdBEM8Pc8vb2Z1/i3PEc4YOr90pWXMkI=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=FhpeVdH1Kd1L1i+aiH6ZTAnpEMiGnXKI4eLLo+4KDpwOZgfM64XZOfBRbSQqQRfHJxb9o7MaIH5uehYKWEdfvbiLoivj0H1WUGjCiLZxsEwl7NWJBycYxy3AWKxlr4SZEthRuPh7LvQA5/1KRYlsNDyDOA0mv5EeeAmbE9xYcAk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=G+oRi4VG; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="G+oRi4VG" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 001A7C4CEEB; Fri, 16 May 2025 11:26:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1747394777; bh=Ii80ZxJgXHUTdBEM8Pc8vb2Z1/i3PEc4YOr90pWXMkI=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=G+oRi4VGSnKZbLkeRauM6bHc9FKkjYD17GUAxoWWJQDc02OlLQU2ssBv3UUEgkmrM yJUV23OLaaVUOyjXhrIT9U7SO0dNA2S3pAAuwNF7zy0JP01vvqyiUUyGWBnqV14Ale 4Cj9Ln7TkSfhvZRZ7QKERWWwwx3O0YqQ7m02FT75FU7Up+uNv4Aup0UtAiG1Qzd2hS BfmN94tnT+RGODuiayiKwM4LjgldINIg+/Q0yR2VGDIrYjLjaimqfVfDaAzqtDc+xj udVF/VhOcadna5gy+q51BGzJFnkotJrj20JpN5o2fDmQUtYXYbn/Xr+TVXdZzSdxty KsEPHJhXVcDkA== From: Christian Brauner Date: Fri, 16 May 2025 13:25:33 +0200 Subject: [PATCH v8 6/9] coredump: show supported coredump modes Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20250516-work-coredump-socket-v8-6-664f3caf2516@kernel.org> References: <20250516-work-coredump-socket-v8-0-664f3caf2516@kernel.org> In-Reply-To: <20250516-work-coredump-socket-v8-0-664f3caf2516@kernel.org> To: linux-fsdevel@vger.kernel.org, Jann Horn , Daniel Borkmann , Kuniyuki Iwashima Cc: Eric Dumazet , Oleg Nesterov , "David S. Miller" , Alexander Viro , Daan De Meyer , David Rheinsberg , Jakub Kicinski , Jan Kara , Lennart Poettering , Luca Boccassi , Mike Yuan , Paolo Abeni , Simon Horman , =?utf-8?q?Zbigniew_J=C4=99drzejewski-Szmek?= , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-security-module@vger.kernel.org, Christian Brauner , Alexander Mikhalitsyn X-Mailer: b4 0.15-dev-6f78e X-Developer-Signature: v=1; a=openpgp-sha256; l=1288; i=brauner@kernel.org; h=from:subject:message-id; bh=Ii80ZxJgXHUTdBEM8Pc8vb2Z1/i3PEc4YOr90pWXMkI=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWSoK2yN+6Ms+3TiB72NRS3ngqrfl8YJyMzQvD1bKfpD/ Anho4lfOkpZGMS4GGTFFFkc2k3C5ZbzVGw2ytSAmcPKBDKEgYtTACbyr5jhf7SQ9/bVMdvL2E98 Zb0rG6j7SHX5wzuaWY/65l5j+/n9ADvDP1UZr2zBmr1PP1z6wP5IhuGfZ4yvkXL5oa1z1kWdz7K J4AcA X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 Allow userspace to discover what coredump modes are supported. Acked-by: Luca Boccassi Reviewed-by: Jann Horn Reviewed-by: Alexander Mikhalitsyn Signed-off-by: Christian Brauner --- fs/coredump.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/fs/coredump.c b/fs/coredump.c index 48064b1d6305..7b9a659683fc 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -1227,6 +1227,12 @@ static int proc_dostring_coredump(const struct ctl_t= able *table, int write, =20 static const unsigned int core_file_note_size_min =3D CORE_FILE_NOTE_SIZE_= DEFAULT; static const unsigned int core_file_note_size_max =3D CORE_FILE_NOTE_SIZE_= MAX; +static char core_modes[] =3D { + "file\npipe" +#ifdef CONFIG_UNIX + "\nsocket" +#endif +}; =20 static const struct ctl_table coredump_sysctls[] =3D { { @@ -1270,6 +1276,13 @@ static const struct ctl_table coredump_sysctls[] =3D= { .extra1 =3D SYSCTL_ZERO, .extra2 =3D SYSCTL_ONE, }, + { + .procname =3D "core_modes", + .data =3D core_modes, + .maxlen =3D sizeof(core_modes) - 1, + .mode =3D 0444, + .proc_handler =3D proc_dostring, + }, }; =20 static int __init init_fs_coredump_sysctls(void) --=20 2.47.2 From nobody Mon Dec 15 02:55:36 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 DA29A236431; Fri, 16 May 2025 11:26:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747394783; cv=none; b=K5jQ0vg7F2qbXjWJOmAuCz3gIxYCYXN/pqQB1KTkDAa0oJ4kOF5UL1Ubno1k47h5PrmB9hUucw9dbsp6isjk9wCrYM3FckWRImsbWYy/xFzfMa4GgOH4AX++1HuT45gnVHlJ7l7oaSv+HO4KncRTBQ/LQdc0cTLyg/iL55tuu3s= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747394783; c=relaxed/simple; bh=cdHC8XIcBNIdLFjlHlwiRrtkhnKb7FpbkKLOq0IziuI=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=LSgJhsHmelYMTgViN2o20iAujlUgrgoRhBUS+d305esUpcAXEv+RJOm3uXEa1QU6vOAIoWBd96qp/J9ZqBfcwqKrfRHHld+lo7l7+5acYGD1AqIOpL4Epa/TZ5yP+G+5jqUT5eJyVsdMSuQOxb6DmDuR7+hHiQHV9rRFzcNLCSg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=kyQJhYJI; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="kyQJhYJI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3EB1AC4CEE4; Fri, 16 May 2025 11:26:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1747394782; bh=cdHC8XIcBNIdLFjlHlwiRrtkhnKb7FpbkKLOq0IziuI=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=kyQJhYJI9pGnMPXVFWedYdnvczVPVcbPy74MhDh7FnQeSybufq49b8RL4d2dGKH+n HxdvUlyi4fHZZRoUOB1Vgq451o2pttbclrDkLZgb9P0W5drdepSPnJ9DRBzPiW+1PH XNHRJNuqm9aVHuyq1p/cE/5BbM5xHD0uYeXt97GjvAx0sQS7VmrB0+k0BuOAMXDjxj LXH2+NoK2BfrKwbpv+VhcWBaK4nUPLftgu7Md7/sKpMcG/VdVy+Z2hxiyqtNTurD1b UW0gA6b4tjMIIfwbzkWwYIez3lYFnswtIkS78EKuKlE9W0qWS3+5WDxkG6XOJiHlFM Tah9xrmBty54Q== From: Christian Brauner Date: Fri, 16 May 2025 13:25:34 +0200 Subject: [PATCH v8 7/9] coredump: validate socket name as it is written Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20250516-work-coredump-socket-v8-7-664f3caf2516@kernel.org> References: <20250516-work-coredump-socket-v8-0-664f3caf2516@kernel.org> In-Reply-To: <20250516-work-coredump-socket-v8-0-664f3caf2516@kernel.org> To: linux-fsdevel@vger.kernel.org, Jann Horn , Daniel Borkmann , Kuniyuki Iwashima Cc: Eric Dumazet , Oleg Nesterov , "David S. Miller" , Alexander Viro , Daan De Meyer , David Rheinsberg , Jakub Kicinski , Jan Kara , Lennart Poettering , Luca Boccassi , Mike Yuan , Paolo Abeni , Simon Horman , =?utf-8?q?Zbigniew_J=C4=99drzejewski-Szmek?= , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-security-module@vger.kernel.org, Christian Brauner , Alexander Mikhalitsyn X-Mailer: b4 0.15-dev-6f78e X-Developer-Signature: v=1; a=openpgp-sha256; l=1893; i=brauner@kernel.org; h=from:subject:message-id; bh=cdHC8XIcBNIdLFjlHlwiRrtkhnKb7FpbkKLOq0IziuI=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWSoK2zdde9lejNPSz732qlnNYUq0+MXLnj25NSkP7umO zUd+GR/r6OUhUGMi0FWTJHFod0kXG45T8Vmo0wNmDmsTCBDGLg4BWAi5QqMDJ0bH3EfnXi663Px +292Lpp7Vhw0PSpT1j6//U5JWMrlvxoM/51Sn9/oz/Hvv1JW8HypjWjwibrLHMueW55IuM1SGf2 2kx0A X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 In contrast to other parameters written into /proc/sys/kernel/core_pattern that never fail we can validate enabling the new AF_UNIX support. This is obviously racy as hell but it's always been that way. Acked-by: Luca Boccassi Reviewed-by: Jann Horn Reviewed-by: Alexander Mikhalitsyn Signed-off-by: Christian Brauner --- fs/coredump.c | 37 ++++++++++++++++++++++++++++++++++--- 1 file changed, 34 insertions(+), 3 deletions(-) diff --git a/fs/coredump.c b/fs/coredump.c index 7b9a659683fc..c5c57e8e496f 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -1215,13 +1215,44 @@ void validate_coredump_safety(void) } } =20 +static inline bool check_coredump_socket(void) +{ + if (core_pattern[0] !=3D '@') + return true; + + /* + * Coredump socket must be located in the initial mount + * namespace. Don't give the impression that anything else is + * supported right now. + */ + if (current->nsproxy->mnt_ns !=3D init_task.nsproxy->mnt_ns) + return false; + + /* Must be an absolute path. */ + if (*(core_pattern + 1) !=3D '/') + return false; + + return true; +} + static int proc_dostring_coredump(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { - int error =3D proc_dostring(table, write, buffer, lenp, ppos); + int error; + ssize_t retval; + char old_core_pattern[CORENAME_MAX_SIZE]; + + retval =3D strscpy(old_core_pattern, core_pattern, CORENAME_MAX_SIZE); + + error =3D proc_dostring(table, write, buffer, lenp, ppos); + if (error) + return error; + if (!check_coredump_socket()) { + strscpy(core_pattern, old_core_pattern, retval + 1); + return -EINVAL; + } =20 - if (!error) - validate_coredump_safety(); + validate_coredump_safety(); return error; } =20 --=20 2.47.2 From nobody Mon Dec 15 02:55:36 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 3017C237180; Fri, 16 May 2025 11:26:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747394788; cv=none; b=kIuBpMYy/CWUlAaiVC5soaqVUXqktKs/nZoDWmVZfVW5EPvonMHPGt3P/9J457/N3PAZDWvi6W0jh7nNULjcVF0n9ot06tmHryk7DmyU3KaTrHUS079aWGo9yQm4CfB+C2cWA99PPVWJyWgAyHdwx6uWtumkvRHe/k/ZtbB/1IU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747394788; c=relaxed/simple; bh=BpKwYMdV1GtmnJFOT8ouIh8HQZHbI95yXB+KWWXUyU4=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=AEPxxAeSPc/zhkKsiI2/y/lkjW2ItFV/af3e6gb+UavVarz4aJH9ZEbby9N/780jfyosRxs6sur6FfxRR/m+TsTtMj57LbXA8vkK25+QOaUy3wKgrvPGDCr2+mUsPJFZaTLXbAj8rhT4bA6aC0cGxO6c16qyGit8o9OGTTG+ZqI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=IJw8vE3V; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="IJw8vE3V" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3389CC4CEEB; Fri, 16 May 2025 11:26:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1747394787; bh=BpKwYMdV1GtmnJFOT8ouIh8HQZHbI95yXB+KWWXUyU4=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=IJw8vE3VWBg50EPR2Q062FHQbDBCqMvJfRaQUxdTjooocb5oCN/vcmhkc7lu9cp8t RhTVz7YevfK3iaF+R/UTkmmDtviV3bBpyDTceEl96R7E6BaKVg1L83ykktyBy78Y4H vVc4JPQ6F/0gMSiNHD8hMAUwjx8su6SbpZxgaDctKGhVNRIla9yhMwANn1fgvVxFX9 WDCSAzAkK60HW323A0q4J0LWwMJZzNAzI2ILMu2gDgkgACKw8TjGrLc7jadSlkaepW jDTKBdXmvnJYGVTEh3DwIY/3Jb58ZGPkZcoO2vf8+vQEncRRW6B9Cbt0QIv2gfg36i gZvbY+4owQYIQ== From: Christian Brauner Date: Fri, 16 May 2025 13:25:35 +0200 Subject: [PATCH v8 8/9] selftests/pidfd: add PIDFD_INFO_COREDUMP infrastructure Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20250516-work-coredump-socket-v8-8-664f3caf2516@kernel.org> References: <20250516-work-coredump-socket-v8-0-664f3caf2516@kernel.org> In-Reply-To: <20250516-work-coredump-socket-v8-0-664f3caf2516@kernel.org> To: linux-fsdevel@vger.kernel.org, Jann Horn , Daniel Borkmann , Kuniyuki Iwashima Cc: Eric Dumazet , Oleg Nesterov , "David S. Miller" , Alexander Viro , Daan De Meyer , David Rheinsberg , Jakub Kicinski , Jan Kara , Lennart Poettering , Luca Boccassi , Mike Yuan , Paolo Abeni , Simon Horman , =?utf-8?q?Zbigniew_J=C4=99drzejewski-Szmek?= , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-security-module@vger.kernel.org, Christian Brauner , Alexander Mikhalitsyn X-Mailer: b4 0.15-dev-6f78e X-Developer-Signature: v=1; a=openpgp-sha256; l=1479; i=brauner@kernel.org; h=from:subject:message-id; bh=BpKwYMdV1GtmnJFOT8ouIh8HQZHbI95yXB+KWWXUyU4=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWSoK2zz41pg/qKqVrApSFrripTy0SO60SujY1X7BWPeP 8879y2so5SFQYyLQVZMkcWh3SRcbjlPxWajTA2YOaxMIEMYuDgFYCIFiQw/GWerv/ZcKdZ7hX1R uJFH9939K155HWA7sDLTYemseTsEKxgZHusw2gYYihm+/nMkIvv1v8vMUx39HxryNCVFCbm3/NF lBAA= X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 Add PIDFD_INFO_COREDUMP infrastructure so we can use it in tests. Acked-by: Luca Boccassi Reviewed-by: Alexander Mikhalitsyn Signed-off-by: Christian Brauner --- tools/testing/selftests/pidfd/pidfd.h | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/tools/testing/selftests/pidfd/pidfd.h b/tools/testing/selftest= s/pidfd/pidfd.h index 55bcf81a2b9a..efd74063126e 100644 --- a/tools/testing/selftests/pidfd/pidfd.h +++ b/tools/testing/selftests/pidfd/pidfd.h @@ -131,6 +131,26 @@ #define PIDFD_INFO_EXIT (1UL << 3) /* Always returned if available, even= if not requested */ #endif =20 +#ifndef PIDFD_INFO_COREDUMP +#define PIDFD_INFO_COREDUMP (1UL << 4) +#endif + +#ifndef PIDFD_COREDUMPED +#define PIDFD_COREDUMPED (1U << 0) /* Did crash and... */ +#endif + +#ifndef PIDFD_COREDUMP_SKIP +#define PIDFD_COREDUMP_SKIP (1U << 1) /* coredumping generation was skippe= d. */ +#endif + +#ifndef PIDFD_COREDUMP_USER +#define PIDFD_COREDUMP_USER (1U << 2) /* coredump was done as the user. */ +#endif + +#ifndef PIDFD_COREDUMP_ROOT +#define PIDFD_COREDUMP_ROOT (1U << 3) /* coredump was done as root. */ +#endif + #ifndef PIDFD_THREAD #define PIDFD_THREAD O_EXCL #endif @@ -150,6 +170,8 @@ struct pidfd_info { __u32 fsuid; __u32 fsgid; __s32 exit_code; + __u32 coredump_mask; + __u32 __spare1; }; =20 /* --=20 2.47.2 From nobody Mon Dec 15 02:55:36 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 593F423BCEC; Fri, 16 May 2025 11:26:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747394793; cv=none; b=JEx0gL2PGkLt2Bg92wSXWxGq7YTAcOsJjzphkRKd2szj0G6q/jYvH4sh/V5+HVLNZXOnv5dcqsGNwUiw/bp7r46HizbaHj2PqDlSxidyz9MRJsxWKhOBSCsIuoOy9JfoYYmjrG2tUvmFe+nZQxTWPEVomQk8VVLAmpieSPJfxKc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747394793; c=relaxed/simple; bh=CjMXLNxQTUQ+NVWK7UNF0LloR85gncPFDeQLLNmPQqY=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=ft6+UeLJFiDMzgoqSpEwBUq0hBDTo73HRpPww1mbgRy/RvjOK62yl6+funSzypczC3TN+qV0wXEfooUD0imqjE1BikfpTFVtYAHvF1goijIwqQAfOrJVImG5SavHFwAIHB/O6YNn0BcmYettUsp+tvrnS6lP2hHZnkxpCDsrZWE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=uLMsPK0Y; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="uLMsPK0Y" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 245D7C4CEE4; Fri, 16 May 2025 11:26:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1747394792; bh=CjMXLNxQTUQ+NVWK7UNF0LloR85gncPFDeQLLNmPQqY=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=uLMsPK0YTvUJMuBgknFn24RjNHOZY5v8pcYt/B4WmpdAk1QNXchkrcADfUQm4OMO9 spjC1aTTIT1yCzbx/s+b+l0R0CxWAy1H02vuA2+FkxoRKnaUafIZdpRFu8BQ91LloW yN/jovsq4P/mc1em774EgSw9mBF7Tn4ME26EoGottAIK9aI7JbiBuxxnHu0D1B8aFO WpYoFvqxhJCYakY4caUMAyBNB4j+yv5+V9Z/HsxcCTJMHeclxT+OqHCwqcCfRUPmx2 TK4RSNtZ3Yd1illREo4g8FYQi5PzpO+FYpVsUl0glioOXN1E09rbNmkDCXUbBcm7+x Ekqyf17L8xKAA== From: Christian Brauner Date: Fri, 16 May 2025 13:25:36 +0200 Subject: [PATCH v8 9/9] selftests/coredump: add tests for AF_UNIX coredumps Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20250516-work-coredump-socket-v8-9-664f3caf2516@kernel.org> References: <20250516-work-coredump-socket-v8-0-664f3caf2516@kernel.org> In-Reply-To: <20250516-work-coredump-socket-v8-0-664f3caf2516@kernel.org> To: linux-fsdevel@vger.kernel.org, Jann Horn , Daniel Borkmann , Kuniyuki Iwashima Cc: Eric Dumazet , Oleg Nesterov , "David S. Miller" , Alexander Viro , Daan De Meyer , David Rheinsberg , Jakub Kicinski , Jan Kara , Lennart Poettering , Luca Boccassi , Mike Yuan , Paolo Abeni , Simon Horman , =?utf-8?q?Zbigniew_J=C4=99drzejewski-Szmek?= , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-security-module@vger.kernel.org, Christian Brauner , Alexander Mikhalitsyn X-Mailer: b4 0.15-dev-6f78e X-Developer-Signature: v=1; a=openpgp-sha256; l=14551; i=brauner@kernel.org; h=from:subject:message-id; bh=CjMXLNxQTUQ+NVWK7UNF0LloR85gncPFDeQLLNmPQqY=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWSoK2xTcjwQXP/kvOCKRzF3K/6Xq38Rumo42/7Gk3vnd gtu4jmwuqOUhUGMi0FWTJHFod0kXG45T8Vmo0wNmDmsTCBDGLg4BWAidQsZGabmJSa/mhh4M1Bd 88MHHjGd11YXhRQzpm6bbRV4afPLOBeGfxbv3xy9wtRw68KlfxdaQ7Yo3NvmfHAW245nLgphpVt 6l/MBAA== X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 Add a simple test for generating coredumps via AF_UNIX sockets. Acked-by: Luca Boccassi Reviewed-by: Alexander Mikhalitsyn Signed-off-by: Christian Brauner --- tools/testing/selftests/coredump/stackdump_test.c | 467 ++++++++++++++++++= +++- 1 file changed, 466 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/coredump/stackdump_test.c b/tools/test= ing/selftests/coredump/stackdump_test.c index fe3c728cd6be..9984413be9f0 100644 --- a/tools/testing/selftests/coredump/stackdump_test.c +++ b/tools/testing/selftests/coredump/stackdump_test.c @@ -1,14 +1,20 @@ // SPDX-License-Identifier: GPL-2.0 =20 #include +#include #include #include #include #include +#include #include +#include +#include +#include #include =20 #include "../kselftest_harness.h" +#include "../pidfd/pidfd.h" =20 #define STACKDUMP_FILE "stack_values" #define STACKDUMP_SCRIPT "stackdump" @@ -35,6 +41,7 @@ static void crashing_child(void) FIXTURE(coredump) { char original_core_pattern[256]; + pid_t pid_coredump_server; }; =20 FIXTURE_SETUP(coredump) @@ -44,6 +51,7 @@ FIXTURE_SETUP(coredump) char *dir; int ret; =20 + self->pid_coredump_server =3D -ESRCH; file =3D fopen("/proc/sys/kernel/core_pattern", "r"); ASSERT_NE(NULL, file); =20 @@ -61,10 +69,17 @@ FIXTURE_TEARDOWN(coredump) { const char *reason; FILE *file; - int ret; + int ret, status; =20 unlink(STACKDUMP_FILE); =20 + if (self->pid_coredump_server > 0) { + kill(self->pid_coredump_server, SIGTERM); + waitpid(self->pid_coredump_server, &status, 0); + } + unlink("/tmp/coredump.file"); + unlink("/tmp/coredump.socket"); + file =3D fopen("/proc/sys/kernel/core_pattern", "w"); if (!file) { reason =3D "Unable to open core_pattern"; @@ -154,4 +169,454 @@ TEST_F_TIMEOUT(coredump, stackdump, 120) fclose(file); } =20 +TEST_F(coredump, socket) +{ + int fd, pidfd, ret, status; + FILE *file; + pid_t pid, pid_coredump_server; + struct stat st; + char core_file[PATH_MAX]; + struct pidfd_info info =3D {}; + int ipc_sockets[2]; + char c; + const struct sockaddr_un coredump_sk =3D { + .sun_family =3D AF_UNIX, + .sun_path =3D "/tmp/coredump.socket", + }; + size_t coredump_sk_len =3D offsetof(struct sockaddr_un, sun_path) + + sizeof("/tmp/coredump.socket"); + + ret =3D socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0, ipc_sockets); + ASSERT_EQ(ret, 0); + + file =3D fopen("/proc/sys/kernel/core_pattern", "w"); + ASSERT_NE(file, NULL); + + ret =3D fprintf(file, "@/tmp/coredump.socket"); + ASSERT_EQ(ret, strlen("@/tmp/coredump.socket")); + ASSERT_EQ(fclose(file), 0); + + pid_coredump_server =3D fork(); + ASSERT_GE(pid_coredump_server, 0); + if (pid_coredump_server =3D=3D 0) { + int fd_server, fd_coredump, fd_peer_pidfd, fd_core_file; + socklen_t fd_peer_pidfd_len; + + close(ipc_sockets[0]); + + fd_server =3D socket(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0); + if (fd_server < 0) + _exit(EXIT_FAILURE); + + ret =3D bind(fd_server, (const struct sockaddr *)&coredump_sk, coredump_= sk_len); + if (ret < 0) { + fprintf(stderr, "Failed to bind coredump socket\n"); + close(fd_server); + close(ipc_sockets[1]); + _exit(EXIT_FAILURE); + } + + ret =3D listen(fd_server, 1); + if (ret < 0) { + fprintf(stderr, "Failed to listen on coredump socket\n"); + close(fd_server); + close(ipc_sockets[1]); + _exit(EXIT_FAILURE); + } + + if (write_nointr(ipc_sockets[1], "1", 1) < 0) { + close(fd_server); + close(ipc_sockets[1]); + _exit(EXIT_FAILURE); + } + + close(ipc_sockets[1]); + + fd_coredump =3D accept4(fd_server, NULL, NULL, SOCK_CLOEXEC); + if (fd_coredump < 0) { + fprintf(stderr, "Failed to accept coredump socket connection\n"); + close(fd_server); + _exit(EXIT_FAILURE); + } + + fd_peer_pidfd_len =3D sizeof(fd_peer_pidfd); + ret =3D getsockopt(fd_coredump, SOL_SOCKET, SO_PEERPIDFD, + &fd_peer_pidfd, &fd_peer_pidfd_len); + if (ret < 0) { + fprintf(stderr, "%m - Failed to retrieve peer pidfd for coredump socket= connection\n"); + close(fd_coredump); + close(fd_server); + _exit(EXIT_FAILURE); + } + + memset(&info, 0, sizeof(info)); + info.mask =3D PIDFD_INFO_EXIT | PIDFD_INFO_COREDUMP; + ret =3D ioctl(fd_peer_pidfd, PIDFD_GET_INFO, &info); + if (ret < 0) { + fprintf(stderr, "Failed to retrieve pidfd info from peer pidfd for core= dump socket connection\n"); + close(fd_coredump); + close(fd_server); + close(fd_peer_pidfd); + _exit(EXIT_FAILURE); + } + + if (!(info.mask & PIDFD_INFO_COREDUMP)) { + fprintf(stderr, "Missing coredump information from coredumping task\n"); + close(fd_coredump); + close(fd_server); + close(fd_peer_pidfd); + _exit(EXIT_FAILURE); + } + + if (!(info.coredump_mask & PIDFD_COREDUMPED)) { + fprintf(stderr, "Received connection from non-coredumping task\n"); + close(fd_coredump); + close(fd_server); + close(fd_peer_pidfd); + _exit(EXIT_FAILURE); + } + + fd_core_file =3D creat("/tmp/coredump.file", 0644); + if (fd_core_file < 0) { + fprintf(stderr, "Failed to create coredump file\n"); + close(fd_coredump); + close(fd_server); + close(fd_peer_pidfd); + _exit(EXIT_FAILURE); + } + + for (;;) { + char buffer[4096]; + ssize_t bytes_read, bytes_write; + + bytes_read =3D read(fd_coredump, buffer, sizeof(buffer)); + if (bytes_read < 0) { + close(fd_coredump); + close(fd_server); + close(fd_peer_pidfd); + close(fd_core_file); + _exit(EXIT_FAILURE); + } + + if (bytes_read =3D=3D 0) + break; + + bytes_write =3D write(fd_core_file, buffer, bytes_read); + if (bytes_read !=3D bytes_write) { + close(fd_coredump); + close(fd_server); + close(fd_peer_pidfd); + close(fd_core_file); + _exit(EXIT_FAILURE); + } + } + + close(fd_coredump); + close(fd_server); + close(fd_peer_pidfd); + close(fd_core_file); + _exit(EXIT_SUCCESS); + } + self->pid_coredump_server =3D pid_coredump_server; + + EXPECT_EQ(close(ipc_sockets[1]), 0); + ASSERT_EQ(read_nointr(ipc_sockets[0], &c, 1), 1); + EXPECT_EQ(close(ipc_sockets[0]), 0); + + pid =3D fork(); + ASSERT_GE(pid, 0); + if (pid =3D=3D 0) + crashing_child(); + + pidfd =3D sys_pidfd_open(pid, 0); + ASSERT_GE(pidfd, 0); + + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFSIGNALED(status)); + ASSERT_TRUE(WCOREDUMP(status)); + + info.mask =3D PIDFD_INFO_EXIT | PIDFD_INFO_COREDUMP; + ASSERT_EQ(ioctl(pidfd, PIDFD_GET_INFO, &info), 0); + ASSERT_GT((info.mask & PIDFD_INFO_COREDUMP), 0); + ASSERT_GT((info.coredump_mask & PIDFD_COREDUMPED), 0); + + waitpid(pid_coredump_server, &status, 0); + self->pid_coredump_server =3D -ESRCH; + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), 0); + + ASSERT_EQ(stat("/tmp/coredump.file", &st), 0); + ASSERT_GT(st.st_size, 0); + /* + * We should somehow validate the produced core file. + * For now just allow for visual inspection + */ + system("file /tmp/coredump.file"); +} + +TEST_F(coredump, socket_detect_userspace_client) +{ + int fd, pidfd, ret, status; + FILE *file; + pid_t pid, pid_coredump_server; + struct stat st; + char core_file[PATH_MAX]; + struct pidfd_info info =3D {}; + int ipc_sockets[2]; + char c; + const struct sockaddr_un coredump_sk =3D { + .sun_family =3D AF_UNIX, + .sun_path =3D "/tmp/coredump.socket", + }; + size_t coredump_sk_len =3D offsetof(struct sockaddr_un, sun_path) + + sizeof("/tmp/coredump.socket"); + + file =3D fopen("/proc/sys/kernel/core_pattern", "w"); + ASSERT_NE(file, NULL); + + ret =3D fprintf(file, "@/tmp/coredump.socket"); + ASSERT_EQ(ret, strlen("@/tmp/coredump.socket")); + ASSERT_EQ(fclose(file), 0); + + ret =3D socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0, ipc_sockets); + ASSERT_EQ(ret, 0); + + pid_coredump_server =3D fork(); + ASSERT_GE(pid_coredump_server, 0); + if (pid_coredump_server =3D=3D 0) { + int fd_server, fd_coredump, fd_peer_pidfd, fd_core_file; + socklen_t fd_peer_pidfd_len; + + close(ipc_sockets[0]); + + fd_server =3D socket(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0); + if (fd_server < 0) + _exit(EXIT_FAILURE); + + ret =3D bind(fd_server, (const struct sockaddr *)&coredump_sk, coredump_= sk_len); + if (ret < 0) { + fprintf(stderr, "Failed to bind coredump socket\n"); + close(fd_server); + close(ipc_sockets[1]); + _exit(EXIT_FAILURE); + } + + ret =3D listen(fd_server, 1); + if (ret < 0) { + fprintf(stderr, "Failed to listen on coredump socket\n"); + close(fd_server); + close(ipc_sockets[1]); + _exit(EXIT_FAILURE); + } + + if (write_nointr(ipc_sockets[1], "1", 1) < 0) { + close(fd_server); + close(ipc_sockets[1]); + _exit(EXIT_FAILURE); + } + + close(ipc_sockets[1]); + + fd_coredump =3D accept4(fd_server, NULL, NULL, SOCK_CLOEXEC); + if (fd_coredump < 0) { + fprintf(stderr, "Failed to accept coredump socket connection\n"); + close(fd_server); + _exit(EXIT_FAILURE); + } + + fd_peer_pidfd_len =3D sizeof(fd_peer_pidfd); + ret =3D getsockopt(fd_coredump, SOL_SOCKET, SO_PEERPIDFD, + &fd_peer_pidfd, &fd_peer_pidfd_len); + if (ret < 0) { + fprintf(stderr, "%m - Failed to retrieve peer pidfd for coredump socket= connection\n"); + close(fd_coredump); + close(fd_server); + _exit(EXIT_FAILURE); + } + + memset(&info, 0, sizeof(info)); + info.mask =3D PIDFD_INFO_EXIT | PIDFD_INFO_COREDUMP; + ret =3D ioctl(fd_peer_pidfd, PIDFD_GET_INFO, &info); + if (ret < 0) { + fprintf(stderr, "Failed to retrieve pidfd info from peer pidfd for core= dump socket connection\n"); + close(fd_coredump); + close(fd_server); + close(fd_peer_pidfd); + _exit(EXIT_FAILURE); + } + + if (!(info.mask & PIDFD_INFO_COREDUMP)) { + fprintf(stderr, "Missing coredump information from coredumping task\n"); + close(fd_coredump); + close(fd_server); + close(fd_peer_pidfd); + _exit(EXIT_FAILURE); + } + + if (info.coredump_mask & PIDFD_COREDUMPED) { + fprintf(stderr, "Received unexpected connection from coredumping task\n= "); + close(fd_coredump); + close(fd_server); + close(fd_peer_pidfd); + _exit(EXIT_FAILURE); + } + + close(fd_coredump); + close(fd_server); + close(fd_peer_pidfd); + close(fd_core_file); + _exit(EXIT_SUCCESS); + } + self->pid_coredump_server =3D pid_coredump_server; + + EXPECT_EQ(close(ipc_sockets[1]), 0); + ASSERT_EQ(read_nointr(ipc_sockets[0], &c, 1), 1); + EXPECT_EQ(close(ipc_sockets[0]), 0); + + pid =3D fork(); + ASSERT_GE(pid, 0); + if (pid =3D=3D 0) { + int fd_socket; + ssize_t ret; + + fd_socket =3D socket(AF_UNIX, SOCK_STREAM, 0); + if (fd_socket < 0) + _exit(EXIT_FAILURE); + + + ret =3D connect(fd_socket, (const struct sockaddr *)&coredump_sk, coredu= mp_sk_len); + if (ret < 0) + _exit(EXIT_FAILURE); + + (void *)write(fd_socket, &(char){ 0 }, 1); + close(fd_socket); + _exit(EXIT_SUCCESS); + } + + pidfd =3D sys_pidfd_open(pid, 0); + ASSERT_GE(pidfd, 0); + + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), 0); + + info.mask =3D PIDFD_INFO_EXIT | PIDFD_INFO_COREDUMP; + ASSERT_EQ(ioctl(pidfd, PIDFD_GET_INFO, &info), 0); + ASSERT_GT((info.mask & PIDFD_INFO_COREDUMP), 0); + ASSERT_EQ((info.coredump_mask & PIDFD_COREDUMPED), 0); + + waitpid(pid_coredump_server, &status, 0); + self->pid_coredump_server =3D -ESRCH; + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), 0); + + ASSERT_NE(stat("/tmp/coredump.file", &st), 0); + ASSERT_EQ(errno, ENOENT); +} + +TEST_F(coredump, socket_enoent) +{ + int pidfd, ret, status; + FILE *file; + pid_t pid; + char core_file[PATH_MAX]; + + file =3D fopen("/proc/sys/kernel/core_pattern", "w"); + ASSERT_NE(file, NULL); + + ret =3D fprintf(file, "@/tmp/coredump.socket"); + ASSERT_EQ(ret, strlen("@/tmp/coredump.socket")); + ASSERT_EQ(fclose(file), 0); + + pid =3D fork(); + ASSERT_GE(pid, 0); + if (pid =3D=3D 0) + crashing_child(); + + pidfd =3D sys_pidfd_open(pid, 0); + ASSERT_GE(pidfd, 0); + + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFSIGNALED(status)); + ASSERT_FALSE(WCOREDUMP(status)); +} + +TEST_F(coredump, socket_no_listener) +{ + int pidfd, ret, status; + FILE *file; + pid_t pid, pid_coredump_server; + int ipc_sockets[2]; + char c; + const struct sockaddr_un coredump_sk =3D { + .sun_family =3D AF_UNIX, + .sun_path =3D "/tmp/coredump.socket", + }; + size_t coredump_sk_len =3D offsetof(struct sockaddr_un, sun_path) + + sizeof("/tmp/coredump.socket"); + + ret =3D socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0, ipc_sockets); + ASSERT_EQ(ret, 0); + + file =3D fopen("/proc/sys/kernel/core_pattern", "w"); + ASSERT_NE(file, NULL); + + ret =3D fprintf(file, "@/tmp/coredump.socket"); + ASSERT_EQ(ret, strlen("@/tmp/coredump.socket")); + ASSERT_EQ(fclose(file), 0); + + pid_coredump_server =3D fork(); + ASSERT_GE(pid_coredump_server, 0); + if (pid_coredump_server =3D=3D 0) { + int fd_server; + socklen_t fd_peer_pidfd_len; + + close(ipc_sockets[0]); + + fd_server =3D socket(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0); + if (fd_server < 0) + _exit(EXIT_FAILURE); + + ret =3D bind(fd_server, (const struct sockaddr *)&coredump_sk, coredump_= sk_len); + if (ret < 0) { + fprintf(stderr, "Failed to bind coredump socket\n"); + close(fd_server); + close(ipc_sockets[1]); + _exit(EXIT_FAILURE); + } + + if (write_nointr(ipc_sockets[1], "1", 1) < 0) { + close(fd_server); + close(ipc_sockets[1]); + _exit(EXIT_FAILURE); + } + + close(fd_server); + close(ipc_sockets[1]); + _exit(EXIT_SUCCESS); + } + self->pid_coredump_server =3D pid_coredump_server; + + EXPECT_EQ(close(ipc_sockets[1]), 0); + ASSERT_EQ(read_nointr(ipc_sockets[0], &c, 1), 1); + EXPECT_EQ(close(ipc_sockets[0]), 0); + + pid =3D fork(); + ASSERT_GE(pid, 0); + if (pid =3D=3D 0) + crashing_child(); + + pidfd =3D sys_pidfd_open(pid, 0); + ASSERT_GE(pidfd, 0); + + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFSIGNALED(status)); + ASSERT_FALSE(WCOREDUMP(status)); + + waitpid(pid_coredump_server, &status, 0); + self->pid_coredump_server =3D -ESRCH; + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), 0); +} + TEST_HARNESS_MAIN --=20 2.47.2