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seccomp: always propagate NO_NEW_PRIVS on tsync 

[ Upstream commit 103502a35c ]

Before this patch, a process with some permissive seccomp filter
that was applied by root without NO_NEW_PRIVS was able to add
more filters to itself without setting NO_NEW_PRIVS by setting
the new filter from a throwaway thread with NO_NEW_PRIVS.

Signed-off-by: Jann Horn <jann@thejh.net>
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
wifi-calibration
Jann Horn 2015-12-26 06:00:48 +01:00 committed by Sasha Levin
parent aa54b6de2b
commit 9885909665
1 changed files with 11 additions and 11 deletions
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22
kernel/seccomp.c
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@ -317,24 +317,24 @@ static inline void seccomp_sync_threads(void)
put_seccomp_filter(thread);
smp_store_release(&thread->seccomp.filter,
caller->seccomp.filter);
/*
* Don't let an unprivileged task work around
* the no_new_privs restriction by creating
* a thread that sets it up, enters seccomp,
* then dies.
*/
if (task_no_new_privs(caller))
task_set_no_new_privs(thread);
/*
* Opt the other thread into seccomp if needed.
* As threads are considered to be trust-realm
* equivalent (see ptrace_may_access), it is safe to
* allow one thread to transition the other.
*/
if (thread->seccomp.mode == SECCOMP_MODE_DISABLED) {
/*
* Don't let an unprivileged task work around
* the no_new_privs restriction by creating
* a thread that sets it up, enters seccomp,
* then dies.
*/
if (task_no_new_privs(caller))
task_set_no_new_privs(thread);
if (thread->seccomp.mode == SECCOMP_MODE_DISABLED)
seccomp_assign_mode(thread, SECCOMP_MODE_FILTER);
}
}
}