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authorEric W. Biederman <ebiederm@xmission.com>2021-10-20 12:44:00 -0500
committerEric W. Biederman <ebiederm@xmission.com>2021-10-29 14:31:33 -0500
commit941edc5bf174b67f94db19817cbeab0a93e0c32a (patch)
tree7dc80fe260947055907341c051c9dc22efe200aa /kernel/entry
parent26d5badbccddcc063dc5174a2baffd13a23322aa (diff)
exit/syscall_user_dispatch: Send ordinary signals on failure
Use force_fatal_sig instead of calling do_exit directly. This ensures the ordinary signal handling path gets invoked, core dumps as appropriate get created, and for multi-threaded processes all of the threads are terminated not just a single thread. When asked Gabriel Krisman Bertazi <krisman@collabora.com> said [1]: > ebiederm@xmission.com (Eric W. Biederman) asked: > > > Why does do_syscal_user_dispatch call do_exit(SIGSEGV) and > > do_exit(SIGSYS) instead of force_sig(SIGSEGV) and force_sig(SIGSYS)? > > > > Looking at the code these cases are not expected to happen, so I would > > be surprised if userspace depends on any particular behaviour on the > > failure path so I think we can change this. > > Hi Eric, > > There is not really a good reason, and the use case that originated the > feature doesn't rely on it. > > Unless I'm missing yet another problem and others correct me, I think > it makes sense to change it as you described. > > > Is using do_exit in this way something you copied from seccomp? > > I'm not sure, its been a while, but I think it might be just that. The > first prototype of SUD was implemented as a seccomp mode. If at some point it becomes interesting we could relax "force_fatal_sig(SIGSEGV)" to instead say "force_sig_fault(SIGSEGV, SEGV_MAPERR, sd->selector)". I avoid doing that in this patch to avoid making it possible to catch currently uncatchable signals. Cc: Gabriel Krisman Bertazi <krisman@collabora.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andy Lutomirski <luto@kernel.org> [1] https://lkml.kernel.org/r/87mtr6gdvi.fsf@collabora.com Link: https://lkml.kernel.org/r/20211020174406.17889-14-ebiederm@xmission.com Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Diffstat (limited to 'kernel/entry')
-rw-r--r--kernel/entry/syscall_user_dispatch.c12
1 files changed, 8 insertions, 4 deletions
diff --git a/kernel/entry/syscall_user_dispatch.c b/kernel/entry/syscall_user_dispatch.c
index c240302f56e2..4508201847d2 100644
--- a/kernel/entry/syscall_user_dispatch.c
+++ b/kernel/entry/syscall_user_dispatch.c
@@ -47,14 +47,18 @@ bool syscall_user_dispatch(struct pt_regs *regs)
* access_ok() is performed once, at prctl time, when
* the selector is loaded by userspace.
*/
- if (unlikely(__get_user(state, sd->selector)))
- do_exit(SIGSEGV);
+ if (unlikely(__get_user(state, sd->selector))) {
+ force_fatal_sig(SIGSEGV);
+ return true;
+ }
if (likely(state == SYSCALL_DISPATCH_FILTER_ALLOW))
return false;
- if (state != SYSCALL_DISPATCH_FILTER_BLOCK)
- do_exit(SIGSYS);
+ if (state != SYSCALL_DISPATCH_FILTER_BLOCK) {
+ force_fatal_sig(SIGSYS);
+ return true;
+ }
}
sd->on_dispatch = true;