Re: [PATCH] Smack: Handle io_uring kernel thread privileges.
From: Eric W. Biederman <hidden>
Date: 2020-12-21 19:56:41
Also in:
lkml
Casey Schaufler [off-list ref] writes:
Smack assumes that kernel threads are privileged for smackfs operations. This was necessary because the credential of the kernel thread was not related to a user operation. With io_uring the credential does reflect a user's rights and can be used.
Acked-by: "Eric W. Biederman" <redacted>
quoted hunk
Suggested-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com> --- security/smack/smack_access.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)diff --git a/security/smack/smack_access.c b/security/smack/smack_access.c index efe2406a3960..7eabb448acab 100644 --- a/security/smack/smack_access.c +++ b/security/smack/smack_access.c@@ -688,9 +688,10 @@ bool smack_privileged_cred(int cap, const struct cred *cred) bool smack_privileged(int cap) { /* - * All kernel tasks are privileged + * Kernel threads may not have credentials we can use. + * The io_uring kernel threads do have reliable credentials. */ - if (unlikely(current->flags & PF_KTHREAD)) + if ((current->flags & (PF_KTHREAD | PF_IO_WORKER)) == PF_KTHREAD) return true; return smack_privileged_cred(cap, current_cred());