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Date: Thu, 17 Dec 2020 17:12:29 -0800 From: Casey Schaufler <casey@...aufler-ca.com> To: "SMACK-discuss@...ts.01.org" <SMACK-discuss@...ts.01.org>, Linux Security Module list <linux-security-module@...r.kernel.org> Cc: Jens Axboe <axboe@...nel.dk>, "Eric W. Biederman" <ebiederm@...ssion.com>, Casey Schaufler <casey@...aufler-ca.com>, LKML <linux-kernel@...r.kernel.org> Subject: [PATCH] Smack: Handle io_uring kernel thread privileges. 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. Suggested-by: Jens Axboe <axboe@...nel.dk> Signed-off-by: Casey Schaufler <casey@...aufler-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());
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