Re: [PATCH v3 2/2] proc: ensure security hook is called after exec

[Stephen Smalley]

On Fri, Dec 18, 2020 at 7:06 PM Stephen Brennan
<stephen.s.brennan@xxxxxxxxxx> wrote:
>
> Smack needs its security_task_to_inode() hook to be called when a task
> execs a new executable. Store the self_exec_id of the task and call the
> hook via pid_update_inode() whenever the exec_id changes.
>
> Signed-off-by: Stephen Brennan <stephen.s.brennan@xxxxxxxxxx>

Sorry to be late in responding, but the proc inode security structure
needs to be updated not only upon a context-changing exec but also
upon a setcon(3) aka write to /proc/self/attr/current just like the
uid/gid needs to be updated not only upon a setuid exec but also upon
a setuid(2).  I'm also unclear as to why you can't call
security_task_to_inode during RCU lookup; it doesn't block/sleep
AFAICT.
All it does is take a spinlock and update a few fields.