From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: "Christian Göttsche" <cgzones@googlemail.com>,
"Jarkko Sakkinen" <jarkko@kernel.org>,
"Sasha Levin" <sashal@kernel.org>,
dhowells@redhat.com, paul@paul-moore.com, jmorris@namei.org,
serge@hallyn.com, keyrings@vger.kernel.org,
linux-security-module@vger.kernel.org
Subject: [PATCH AUTOSEL 5.10 24/25] security: keys: perform capable check only on privileged operations
Date: Sun, 13 Aug 2023 12:09:35 -0400 [thread overview]
Message-ID: <20230813160936.1082758-24-sashal@kernel.org> (raw)
In-Reply-To: <20230813160936.1082758-1-sashal@kernel.org>
From: Christian Göttsche <cgzones@googlemail.com>
[ 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: Christian Göttsche <cgzones@googlemail.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
security/keys/keyctl.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index 61a614c21b9b6..e3ffaf5ad6394 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -980,14 +980,19 @@ 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;
}
@@ -1088,7 +1093,7 @@ 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;
notify_key(key, NOTIFY_KEY_SETATTR, 0);
ret = 0;
--
2.40.1
parent reply other threads:[~2023-08-13 16:12 UTC|newest]
Thread overview: expand[flat|nested] mbox.gz Atom feed
[parent not found: <20230813160936.1082758-1-sashal@kernel.org>]
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