# \[PATCH\] Revert "Smack: Handle io\_uring kernel thread privileges" - Subsystems: SECURITY SUBSYSTEM, SMACK SECURITY MODULE, THE REST - Maintainers: Paul Moore, James Morris, "Serge E. Hallyn", Casey Schaufler, Linus Torvalds - List: linux-security-module - 4 messages, 2 authors - Page: https://ratatoskr.run/linux-security-module/2021/03/6315995/t ## \[PATCH\] Revert "Smack: Handle io\_uring kernel thread privileges" - From: Jens Axboe \ - Date: 2021-03-26 00:43:56 - Message: https://ratatoskr.run/linux-security-module/2021/03/6315995.md ```text This reverts commit 942cb357ae7d9249088e3687ee6a00ed2745a0c7. The io_uring PF_IO_WORKER threads no longer have PF_KTHREAD set, so no need to special case them for credential checks. Cc: Casey Schaufler Signed-off-by: Jens Axboe --- security/smack/smack_access.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/security/smack/smack_access.c b/security/smack/smack_access.c index 7eabb448acab..efe2406a3960 100644 --- a/security/smack/smack_access.c +++ b/security/smack/smack_access.c @@ -688,10 +688,9 @@ bool smack_privileged_cred(int cap, const struct cred *cred) bool smack_privileged(int cap) { /* - * Kernel threads may not have credentials we can use. - * The io_uring kernel threads do have reliable credentials. + * All kernel tasks are privileged */ - if ((current->flags & (PF_KTHREAD | PF_IO_WORKER)) == PF_KTHREAD) + if (unlikely(current->flags & PF_KTHREAD)) return true; return smack_privileged_cred(cap, current_cred()); -- 2.31.0 -- Jens Axboe ``` ## Re: \[PATCH\] Revert "Smack: Handle io\_uring kernel thread privileges" - From: Casey Schaufler \ - Date: 2021-03-26 16:01:20 - Message: https://ratatoskr.run/linux-security-module/2021/03/6316919.md ```text On 3/25/2021 5:42 PM, Jens Axboe wrote: > This reverts commit 942cb357ae7d9249088e3687ee6a00ed2745a0c7. > > The io_uring PF_IO_WORKER threads no longer have PF_KTHREAD set, so no > need to special case them for credential checks. Could you cite the commit making that change? I wouldn't want to see this change back-ported to a kernel that doesn't have that change as well. > > Cc: Casey Schaufler > Signed-off-by: Jens Axboe > --- > security/smack/smack_access.c | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > > diff --git a/security/smack/smack_access.c b/security/smack/smack_access.c > index 7eabb448acab..efe2406a3960 100644 > --- a/security/smack/smack_access.c > +++ b/security/smack/smack_access.c > @@ -688,10 +688,9 @@ bool smack_privileged_cred(int cap, const struct cred *cred) > bool smack_privileged(int cap) > { > /* > - * Kernel threads may not have credentials we can use. > - * The io_uring kernel threads do have reliable credentials. > + * All kernel tasks are privileged > */ > - if ((current->flags & (PF_KTHREAD | PF_IO_WORKER)) == PF_KTHREAD) > + if (unlikely(current->flags & PF_KTHREAD)) > return true; > > return smack_privileged_cred(cap, current_cred()); ``` ## Re: \[PATCH\] Revert "Smack: Handle io\_uring kernel thread privileges" - From: Jens Axboe \ - Date: 2021-03-26 16:06:07 - Message: https://ratatoskr.run/linux-security-module/2021/03/6316940.md ```text On 3/26/21 10:00 AM, Casey Schaufler wrote: > On 3/25/2021 5:42 PM, Jens Axboe wrote: >> This reverts commit 942cb357ae7d9249088e3687ee6a00ed2745a0c7. >> >> The io_uring PF_IO_WORKER threads no longer have PF_KTHREAD set, so no >> need to special case them for credential checks. > > Could you cite the commit making that change? > I wouldn't want to see this change back-ported to a kernel > that doesn't have that change as well. This is strictly 5.12+. The change came about from: commit 3bfe6106693b6b4ba175ad1f929c4660b8f59ca8 Author: Jens Axboe [ref] Date: Tue Feb 16 14:15:30 2021 -0700 io-wq: fork worker threads from original task So don't backport it. -- Jens Axboe ``` ## Re: \[PATCH\] Revert "Smack: Handle io\_uring kernel thread privileges" - From: Casey Schaufler \ - Date: 2021-05-18 17:40:47 - Message: https://ratatoskr.run/linux-security-module/2021/05/1382413.md ```text On 3/25/2021 5:42 PM, Jens Axboe wrote: > This reverts commit 942cb357ae7d9249088e3687ee6a00ed2745a0c7. > > The io_uring PF_IO_WORKER threads no longer have PF_KTHREAD set, so no > need to special case them for credential checks. > > Cc: Casey Schaufler > Signed-off-by: Jens Axboe I have added this to smack-next. Thank you. > --- > security/smack/smack_access.c | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > > diff --git a/security/smack/smack_access.c b/security/smack/smack_access.c > index 7eabb448acab..efe2406a3960 100644 > --- a/security/smack/smack_access.c > +++ b/security/smack/smack_access.c > @@ -688,10 +688,9 @@ bool smack_privileged_cred(int cap, const struct cred *cred) > bool smack_privileged(int cap) > { > /* > - * Kernel threads may not have credentials we can use. > - * The io_uring kernel threads do have reliable credentials. > + * All kernel tasks are privileged > */ > - if ((current->flags & (PF_KTHREAD | PF_IO_WORKER)) == PF_KTHREAD) > + if (unlikely(current->flags & PF_KTHREAD)) > return true; > > return smack_privileged_cred(cap, current_cred()); ```