+ ipc-dont-audit-capability-check-in-ipc_permissions.patch added to mm-nonmm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: ipc: don't audit capability check in ipc_permissions()
has been added to the -mm mm-nonmm-unstable branch.  Its filename is
     ipc-dont-audit-capability-check-in-ipc_permissions.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/ipc-dont-audit-capability-check-in-ipc_permissions.patch

This patch will later appear in the mm-nonmm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Ondrej Mosnacek <omosnace@redhat.com>
Subject: ipc: don't audit capability check in ipc_permissions()
Date: Thu, 22 Jan 2026 15:13:03 +0100

The IPC sysctls implement the ctl_table_root::permissions hook and they
override the file access mode based on the CAP_CHECKPOINT_RESTORE
capability, which is being checked regardless of whether any access is
actually denied or not, so if an LSM denies the capability, an audit
record may be logged even when access is in fact granted.

It wouldn't be viable to restructure the sysctl permission logic to only
check the capability when the access would be actually denied if it's not
granted.  Thus, do the same as in net_ctl_permissions() (net/sysctl_net.c)
- switch from ns_capable() to ns_capable_noaudit(), so that the check
never emits an audit record.

Link: https://lkml.kernel.org/r/20260122141303.241133-1-omosnace@redhat.com
Fixes: 0889f44e2810 ("ipc: Check permissions for checkpoint_restart sysctls at open time")
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Acked-by: Alexey Gladkov <legion@kernel.org>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/capability.h |    6 ++++++
 ipc/ipc_sysctl.c           |    2 +-
 2 files changed, 7 insertions(+), 1 deletion(-)

--- a/include/linux/capability.h~ipc-dont-audit-capability-check-in-ipc_permissions
+++ a/include/linux/capability.h
@@ -203,6 +203,12 @@ static inline bool checkpoint_restore_ns
 		ns_capable(ns, CAP_SYS_ADMIN);
 }
 
+static inline bool checkpoint_restore_ns_capable_noaudit(struct user_namespace *ns)
+{
+	return ns_capable_noaudit(ns, CAP_CHECKPOINT_RESTORE) ||
+		ns_capable_noaudit(ns, CAP_SYS_ADMIN);
+}
+
 /* audit system wants to get cap info from files as well */
 int get_vfs_caps_from_disk(struct mnt_idmap *idmap,
 			   const struct dentry *dentry,
--- a/ipc/ipc_sysctl.c~ipc-dont-audit-capability-check-in-ipc_permissions
+++ a/ipc/ipc_sysctl.c
@@ -214,7 +214,7 @@ static int ipc_permissions(struct ctl_ta
 	if (((table->data == &ns->ids[IPC_SEM_IDS].next_id) ||
 	     (table->data == &ns->ids[IPC_MSG_IDS].next_id) ||
 	     (table->data == &ns->ids[IPC_SHM_IDS].next_id)) &&
-	    checkpoint_restore_ns_capable(ns->user_ns))
+	    checkpoint_restore_ns_capable_noaudit(ns->user_ns))
 		mode = 0666;
 	else
 #endif
_

Patches currently in -mm which might be from omosnace@redhat.com are

ipc-dont-audit-capability-check-in-ipc_permissions.patch