4.19-stable review patch. If anyone has any objections, please let me know.
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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 9394d72a77e80..9e52a3e0fc672 100644 --- a/security/keys/keyctl.c +++ b/security/keys/keyctl.c @@ -922,14 +922,19 @@ 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; }
@@ -1029,7 +1034,7 @@ 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; }