From patchwork Thu Dec 19 20:41:41 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hamza Mahfooz X-Patchwork-Id: 13915765 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by smtp.subspace.kernel.org (Postfix) with ESMTP id E1B4E3FD1; Thu, 19 Dec 2024 20:42:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=13.77.154.182 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734640957; cv=none; b=nnNzI5hBWGAgDi9rWisoNY47xd+WX47Qd0J7rJ6WiqXqTVz/F5H84RtoRqn7mSKjJOnaIxgAHaWRKl4hdvOZQr7u6T215P/oj4DWJ44o1yAeoX8ou5IxfVqqcbsoXoxBHCmM/Kf8Znkq5O6Utd6OUUB9L9sTU6pAEnfbdlE2cW8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734640957; c=relaxed/simple; bh=6DSTopWMJNTlqwjejKr077ARPFYD2iH2vMsPv/ooX6o=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=aB2DZhyk5QXHQDxm8SGYJjuxcjwM138Au2SbXmjQkPiXjKc4c5nt8epxPxMi+7KoJUrLpSX/qBOZ36+UQh9cRCzhkMKBw8tX3sfdGun3wYcXLz0dzqKtustQaZuMkZq/bRwYFIQUeqUu7V1XlCYkqij03Aayy8rQgxOFLxXI4Gg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com; spf=pass smtp.mailfrom=linux.microsoft.com; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b=YMF++CYn; arc=none smtp.client-ip=13.77.154.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="YMF++CYn" Received: from hm-sls2.corp.microsoft.com (bras-base-toroon4332w-grc-63-70-49-166-4.dsl.bell.ca [70.49.166.4]) by linux.microsoft.com (Postfix) with ESMTPSA id 6EFB9203FC94; Thu, 19 Dec 2024 12:42:34 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 6EFB9203FC94 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1734640955; bh=iVZB9ew11Lrxd3x06+Ra7NzDQmQpUub+riVhr6QI1Yk=; h=From:To:Cc:Subject:Date:From; b=YMF++CYnXVuqr38qBKTGY/FrIBR1gwXG6P5cu+XkY4PAPBmgKo1u7j0AihVILJrGO pJmeRJOb97F55RRX2qAgAVnKxNWofj1p8MfEwMUnw+SOrMs/uULp48iXqzv6x2dk5n tqyN2NUymW1T3ZxbliFMRpHGBpyi4Fmi5yil4pTs= From: Hamza Mahfooz To: linux-security-module@vger.kernel.org, io-uring@vger.kernel.org Cc: Hamza Mahfooz , Paul Moore , Jens Axboe , James Morris , "Serge E. Hallyn" , Pavel Begunkov , Stephen Smalley , Ondrej Mosnacek , =?utf-8?q?Thi=C3=A9baud_Weksteen?= , Masahiro Yamada , =?utf-8?q?Bram_Bonn=C3=A9?= , linux-kernel@vger.kernel.org, selinux@vger.kernel.org Subject: [PATCH] lsm,io_uring: add LSM hooks for io_uring_setup() Date: Thu, 19 Dec 2024 15:41:41 -0500 Message-ID: <20241219204143.74736-1-hamzamahfooz@linux.microsoft.com> X-Mailer: git-send-email 2.47.1 Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 It is desirable to allow LSM to configure accessibility to io_uring. So, add an LSM for io_uring_allowed() to guard access to io_uring. Cc: Paul Moore Cc: Jens Axboe Signed-off-by: Hamza Mahfooz --- include/linux/lsm_hook_defs.h | 1 + include/linux/security.h | 5 +++++ io_uring/io_uring.c | 21 ++++++++++++++------- security/security.c | 12 ++++++++++++ security/selinux/hooks.c | 14 ++++++++++++++ security/selinux/include/classmap.h | 2 +- 6 files changed, 47 insertions(+), 8 deletions(-) diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index eb2937599cb0..ee45229418dd 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -456,6 +456,7 @@ LSM_HOOK(int, 0, perf_event_write, struct perf_event *event) LSM_HOOK(int, 0, uring_override_creds, const struct cred *new) LSM_HOOK(int, 0, uring_sqpoll, void) LSM_HOOK(int, 0, uring_cmd, struct io_uring_cmd *ioucmd) +LSM_HOOK(int, 0, uring_allowed, void) #endif /* CONFIG_IO_URING */ LSM_HOOK(void, LSM_RET_VOID, initramfs_populated, void) diff --git a/include/linux/security.h b/include/linux/security.h index cbdba435b798..0a5e897289e8 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -2351,6 +2351,7 @@ static inline int security_perf_event_write(struct perf_event *event) extern int security_uring_override_creds(const struct cred *new); extern int security_uring_sqpoll(void); extern int security_uring_cmd(struct io_uring_cmd *ioucmd); +extern int security_uring_allowed(void); #else static inline int security_uring_override_creds(const struct cred *new) { @@ -2364,6 +2365,10 @@ static inline int security_uring_cmd(struct io_uring_cmd *ioucmd) { return 0; } +extern int security_uring_allowed(void) +{ + return 0; +} #endif /* CONFIG_SECURITY */ #endif /* CONFIG_IO_URING */ diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index 06ff41484e29..0922bb0724c0 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -3806,29 +3806,36 @@ static long io_uring_setup(u32 entries, struct io_uring_params __user *params) return io_uring_create(entries, &p, params); } -static inline bool io_uring_allowed(void) +static inline int io_uring_allowed(void) { int disabled = READ_ONCE(sysctl_io_uring_disabled); kgid_t io_uring_group; if (disabled == 2) - return false; + return -EPERM; if (disabled == 0 || capable(CAP_SYS_ADMIN)) - return true; + goto allowed_lsm; io_uring_group = make_kgid(&init_user_ns, sysctl_io_uring_group); if (!gid_valid(io_uring_group)) - return false; + return -EPERM; + + if (!in_group_p(io_uring_group)) + return -EPERM; - return in_group_p(io_uring_group); +allowed_lsm: + return security_uring_allowed(); } SYSCALL_DEFINE2(io_uring_setup, u32, entries, struct io_uring_params __user *, params) { - if (!io_uring_allowed()) - return -EPERM; + int ret; + + ret = io_uring_allowed(); + if (ret) + return ret; return io_uring_setup(entries, params); } diff --git a/security/security.c b/security/security.c index 09664e09fec9..e4d532e4ead4 100644 --- a/security/security.c +++ b/security/security.c @@ -5996,6 +5996,18 @@ int security_uring_cmd(struct io_uring_cmd *ioucmd) { return call_int_hook(uring_cmd, ioucmd); } + +/** + * security_uring_allowed() - Check if io_uring_setup() is allowed + * + * Check whether the current task is allowed to call io_uring_setup(). + * + * Return: Returns 0 if permission is granted. + */ +int security_uring_allowed(void) +{ + return call_int_hook(uring_allowed); +} #endif /* CONFIG_IO_URING */ /** diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 366c87a40bd1..b4e298c51c16 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -7117,6 +7117,19 @@ static int selinux_uring_cmd(struct io_uring_cmd *ioucmd) return avc_has_perm(current_sid(), isec->sid, SECCLASS_IO_URING, IO_URING__CMD, &ad); } + +/** + * selinux_uring_allowed - check if io_uring_setup() can be called + * + * Check to see if the current task is allowed to call io_uring_setup(). + */ +static int selinux_uring_allowed(void) +{ + u32 sid = current_sid(); + + return avc_has_perm(sid, sid, SECCLASS_IO_URING, IO_URING__ALLOWED, + NULL); +} #endif /* CONFIG_IO_URING */ static const struct lsm_id selinux_lsmid = { @@ -7370,6 +7383,7 @@ static struct security_hook_list selinux_hooks[] __ro_after_init = { LSM_HOOK_INIT(uring_override_creds, selinux_uring_override_creds), LSM_HOOK_INIT(uring_sqpoll, selinux_uring_sqpoll), LSM_HOOK_INIT(uring_cmd, selinux_uring_cmd), + LSM_HOOK_INIT(uring_allowed, selinux_uring_allowed), #endif /* diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h index 2bc20135324a..5ae222f7e543 100644 --- a/security/selinux/include/classmap.h +++ b/security/selinux/include/classmap.h @@ -177,7 +177,7 @@ const struct security_class_mapping secclass_map[] = { { "perf_event", { "open", "cpu", "kernel", "tracepoint", "read", "write", NULL } }, { "anon_inode", { COMMON_FILE_PERMS, NULL } }, - { "io_uring", { "override_creds", "sqpoll", "cmd", NULL } }, + { "io_uring", { "override_creds", "sqpoll", "cmd", "allowed", NULL } }, { "user_namespace", { "create", NULL } }, { NULL } };