Unverified Commit 07158813 authored by Ondrej Mosnacek's avatar Ondrej Mosnacek Committed by Serge Hallyn
Browse files

ipc: don't audit capability check in ipc_permissions() 



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.

Fixes: 0889f44e ("ipc: Check permissions for checkpoint_restart sysctls at open time")
Signed-off-by: default avatarOndrej Mosnacek <omosnace@redhat.com>
Acked-by: default avatarAlexey Gladkov <legion@kernel.org>
Acked-by: default avatarSerge Hallyn <serge@hallyn.com>
Signed-off-by: default avatarSerge Hallyn <sergeh@kernel.org>
parent 24e9b431

include/linux/capability.h

+6 −0
Original line number Diff line number Diff line
@@ -203,6 +203,12 @@ static inline bool checkpoint_restore_ns_capable(struct user_namespace *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,

ipc/ipc_sysctl.c

+1 −1
Original line number Diff line number Diff line
@@ -214,7 +214,7 @@ static int ipc_permissions(struct ctl_table_header *head, const struct ctl_table 
	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