From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 E7C5829DB64; Sat, 12 Sep 2026 16:04:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789229042; cv=none; b=dSY5haz+qX2OGDfWtAPyu2fpfiarp5vbfcriqoUyaYRK0aokjclE2JfiOWuV47GNOrNb+yVxqvu1ycN+/9fObEBVThTqGgb0jQUSFf0gdUem1szmOLTHCOwjadpl3A/inajVKcsJldLukg95mq+hyRQbXcA/Deg+YKHpQJWuBiM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789229042; c=relaxed/simple; bh=oY2oUcBBKZ/WLb46OttygFANRnVQekdeNftI4NPu1rM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=HhRRWdLbWCjGn2OSzzPgAj5bv00HcGdgtFY0LNUcEwYE2gwtxTW+33Rg4RRnmxyydFO569oZFEHanm+/kD1XfKt+GTHVGUmmqRId2jsg9eGD5PzeUVYjb9Y23siVuuGd2WW/Osd/hn03A1gSvmd2BqpVBP7PqQoGJIvS8bsrLEw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=rHEPO84y; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="rHEPO84y" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A3A941F000FF; Sat, 12 Sep 2026 16:03:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789229040; bh=mBc8AAGa/vaJjKj+ELLN/+a8yJuCB3eIzvskgwn0cDo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=rHEPO84yPEqBK6m/7B5jN2Li8J/r8gm5Ln8+KftxJnGR3THyrCwqQXCWY9eOO3Nj+ rcecQI5d6YLJE+SYOHw5gwB962gwdjCHFY1t+tgtcXS9EVzjXmrT4GnvNDDbsjahwi NJ+ZYeCuGZeBlBg7bUgoh2WhK2kINHPOx2anpEW4= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Konstantin Andreev , Casey Schaufler , Sasha Levin Subject: [PATCH 6.1 0467/1191] smack: fix incorrect task context in smack_msg_queue_msgrcv Date: Sat, 12 Sep 2026 08:53:15 +0200 Message-ID: <20260912065558.723854624@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260912065548.086904252@linuxfoundation.org> References: <20260912065548.086904252@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Konstantin Andreev [ Upstream commit fba3d32825f4bbc8e20f0cdc3b14df57965b8fe5 ] The smack_msg_queue_msgrcv() function incorrectly checks the permissions of the 'current' task instead of the 'target' task. In the msgsnd() syscall path, if a receiver is already waiting, the pipelined_send() optimization is used to push the message directly to the receiver task: ipc/msg.c`pipelined_send(): ` smp_store_release(&msr->r_msg, msg) In this case, the 'sender' (current) task performs the check on behalf of the 'receiver' task (msr->r_tsk, passed as the 'target' parameter): ipc/msg.c`pipelined_send(): ` security_msg_queue_msgrcv(,, target := msr->r_tsk,,) However, smack_msg_queue_msgrcv() ignores the 'target' and checks 'current': smack_msg_queue_msgrcv(…) ` smk_curacc_msq(isp, MAY_READWRITE); // current task 'current' MAY satisfy smack_msg_queue_msgrcv r/w requirement, but 'target' (the receiver task) might NOT; as a result, an unauthorized receiver gets the message, violating MAC policy. Test: 1) create a sysv message queue with label “foo” 2) echo "bar foo r" >/smack/load2 3) msgrcv(,,,0,MSG_NOERROR) in "bar"-labeled task. The task is waiting for the messages ... 4) msgsnd() from a "foo"-labeled task: "bar"-labeled task gets the message. This patch fixes the issue by checking permission on the 'target' task instead of 'current'. (2008-02-04, Casey Schaufler) Fixes: e114e473771c ("Smack: Simplified Mandatory Access Control Kernel") Signed-off-by: Konstantin Andreev Signed-off-by: Casey Schaufler Signed-off-by: Sasha Levin --- security/smack/smack_lsm.c | 65 +++++++++++++++++++++++++++----------- 1 file changed, 47 insertions(+), 18 deletions(-) diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c index 8c5bdae927152..0853da7748088 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -136,12 +136,13 @@ static int smk_bu_note(char *note, struct smack_known *sskp, #define smk_bu_note(note, sskp, oskp, mode, RC) (RC) #endif -#ifdef CONFIG_SECURITY_SMACK_BRINGUP -static int smk_bu_current(char *note, struct smack_known *oskp, - int mode, int rc) +static int +smk_bu_tsk_to_obj(struct task_struct *tsk, const struct task_smack *tsp, + char *note, struct smack_known *oskp, int mode, int rc) { - struct task_smack *tsp = smack_cred(current_cred()); +#ifdef CONFIG_SECURITY_SMACK_BRINGUP char acc[SMK_NUM_ACCESS_TYPE + 1]; + char comm[TASK_COMM_LEN]; if (rc <= 0) return rc; @@ -149,14 +150,22 @@ static int smk_bu_current(char *note, struct smack_known *oskp, rc = 0; smk_bu_mode(mode, acc); + pr_info("Smack %s: (%s %s %s) %s %s\n", smk_bu_mess[rc], - tsp->smk_task->smk_known, oskp->smk_known, - acc, current->comm, note); + smk_of_task(tsp)->smk_known, oskp->smk_known, + acc, get_task_comm(comm, tsk), note); return 0; -} #else -#define smk_bu_current(note, oskp, mode, RC) (RC) + return rc; #endif +} + +static int smk_bu_current(char *note, struct smack_known *oskp, + int mode, int rc) +{ + return smk_bu_tsk_to_obj(current, smack_cred(current_cred()), + note, oskp, mode, rc); +} #ifdef CONFIG_SECURITY_SMACK_BRINGUP static int smk_bu_task(struct task_struct *otp, int mode, int rc) @@ -3212,14 +3221,20 @@ static int smack_sem_semop(struct kern_ipc_perm *isp, struct sembuf *sops, } /** - * smk_curacc_msq : helper to check if current has access on msq - * @isp : the msq + * smk_tskacc_msq : helper to check if tsk has access on msq + * @tsk: the task that requests access + * @isp : the sysv msg queue permissions * @access : access requested * - * return 0 if current has access, error otherwise + * return 0 if tsk has access, error otherwise */ -static int smk_curacc_msq(struct kern_ipc_perm *isp, int access) +static int +smk_tskacc_msq(struct task_struct *tsk, struct kern_ipc_perm *isp, int access) { + const bool tsk_is_current = (tsk == current); + const struct cred * const tsk_cred = + (tsk_is_current ? current_cred() : get_task_cred(tsk)); + struct task_smack * const tsp = smack_cred(tsk_cred); struct smack_known *msp = smack_of_ipc(isp); struct smk_audit_info ad; int rc; @@ -3228,11 +3243,25 @@ static int smk_curacc_msq(struct kern_ipc_perm *isp, int access) smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_IPC); ad.a.u.ipc_id = isp->id; #endif - rc = smk_curacc(msp, access, &ad); - rc = smk_bu_current("msq", msp, access, rc); + rc = smk_tskacc(tsp, msp, access, &ad); + rc = smk_bu_tsk_to_obj(tsk, tsp, "msq", msp, access, rc); + if (!tsk_is_current) + put_cred(tsk_cred); return rc; } +/** + * smk_curacc_msq : helper to check if current has access on msq + * @isp : the sysv msg queue permissions + * @access : access requested + * + * return 0 if current has access, error otherwise + */ +static int smk_curacc_msq(struct kern_ipc_perm *isp, int access) +{ + return smk_tskacc_msq(current, isp, access); +} + /** * smack_msg_queue_associate - Smack access check for msg_queue * @isp: the object @@ -3300,21 +3329,21 @@ static int smack_msg_queue_msgsnd(struct kern_ipc_perm *isp, struct msg_msg *msg } /** - * smack_msg_queue_msgrcv - Smack access check for msg_queue + * smack_msg_queue_msgrcv - check it target has r/w access to msg_queue * @isp: the object * @msg: unused - * @target: unused + * @target: the task that msgrcv() from the queue * @type: unused * @mode: unused * - * Returns 0 if current has read and write access, error code otherwise + * Returns 0 if target has read and write access, error code otherwise */ static int smack_msg_queue_msgrcv(struct kern_ipc_perm *isp, struct msg_msg *msg, struct task_struct *target, long type, int mode) { - return smk_curacc_msq(isp, MAY_READWRITE); + return smk_tskacc_msq(target, isp, MAY_READWRITE); } /** -- 2.53.0