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Commit 3899c1d1 authored by Christian Göttsche's avatar Christian Göttsche Committed by Greg Kroah-Hartman
Browse files

security: keys: perform capable check only on privileged operations 



[ Upstream commit 2d7f105edbb3b2be5ffa4d833abbf9b6965e9ce7 ]

If the current task fails the check for the queried capability via
`capable(CAP_SYS_ADMIN)` LSMs like SELinux generate a denial message.
Issuing such denial messages unnecessarily can lead to a policy author
granting more privileges to a subject than needed to silence them.

Reorder CAP_SYS_ADMIN checks after the check whether the operation is
actually privileged.

Signed-off-by: default avatarChristian Göttsche <cgzones@googlemail.com>
Reviewed-by: default avatarJarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: default avatarJarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 97ed1be2

security/keys/keyctl.c

+8 −3
Original line number Diff line number Diff line
@@ -977,14 +977,19 @@ long keyctl_chown_key(key_serial_t id, uid_t user, gid_t group) 
	ret = -EACCES;

	down_write(&key->sem);



	if (!capable(CAP_SYS_ADMIN)) {

	{

		bool is_privileged_op = false;



		/* only the sysadmin can chown a key to some other UID */

		if (user != (uid_t) -1 && !uid_eq(key->uid, uid))

			goto error_put;

			is_privileged_op = true;



		/* only the sysadmin can set the key's GID to a group other

		 * than one of those that the current process subscribes to */

		if (group != (gid_t) -1 && !gid_eq(gid, key->gid) && !in_group_p(gid))

			is_privileged_op = true;



		if (is_privileged_op && !capable(CAP_SYS_ADMIN))

			goto error_put;

	}
@@ -1084,7 +1089,7 @@ long keyctl_setperm_key(key_serial_t id, key_perm_t perm) 
	down_write(&key->sem);



	/* if we're not the sysadmin, we can only change a key that we own */

	if (capable(CAP_SYS_ADMIN) || uid_eq(key->uid, current_fsuid())) {

	if (uid_eq(key->uid, current_fsuid()) || capable(CAP_SYS_ADMIN)) {

		key->perm = perm;

		ret = 0;

	}