[PATCH] Smack: Handle io_uring kernel thread privileges.
Eric W. Biederman
ebiederm at xmission.com
Mon Dec 21 19:55:01 UTC 2020
Casey Schaufler <casey at schaufler-ca.com> 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" <ebiederm at xmission.com>
> Suggested-by: Jens Axboe <axboe at kernel.dk>
> Signed-off-by: Casey Schaufler <casey at 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());
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