keyctl_read_key() has a strange code which allows possessor to read key's payload regardless of READ permission status:
$ keyctl add user test test @u 196773443 $ keyctl print 196773443 test $ keyctl describe 196773443 196773443: alswrv-----v------------ 1000 1000 user: test $ keyctl rdescribe 196773443 user;1000;1000;3f010000;test $ keyctl setperm 196773443 0x3d010000 $ keyctl describe 196773443 196773443: alsw-v-----v------------ 1000 1000 user: test $ keyctl print 196773443 test The last keyctl print should fail with -EACCESS instead of success. Fix this by removing weird possessor checks. Signed-off-by: Andrey Ryabinin <[email protected]> --- - This was noticed by code review. It seems like a bug to me, but if I'm wrong and current behavior is correct, I think we need at least better comment here. security/keys/keyctl.c | 15 +-------------- 1 file changed, 1 insertion(+), 14 deletions(-) diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c index 96a92a645216d..2ec021c7adc12 100644 --- a/security/keys/keyctl.c +++ b/security/keys/keyctl.c @@ -845,22 +845,9 @@ long keyctl_read_key(key_serial_t keyid, char __user *buffer, size_t buflen) /* see if we can read it directly */ ret = key_permission(key_ref, KEY_NEED_READ); - if (ret == 0) - goto can_read_key; - if (ret != -EACCES) + if (ret != 0) goto key_put_out; - /* we can't; see if it's searchable from this process's keyrings - * - we automatically take account of the fact that it may be - * dangling off an instantiation key - */ - if (!is_key_possessed(key_ref)) { - ret = -EACCES; - goto key_put_out; - } - - /* the key is probably readable - now try to read it */ -can_read_key: if (!key->type->read) { ret = -EOPNOTSUPP; goto key_put_out; -- 2.26.2
