core dump: remain dumpable
The coredump code always calls set_dumpable(0) when it starts (even
if RLIMIT_CORE prevents any core from being dumped). The effect of
this (via task_dumpable) is to make /proc/pid/* files owned by root
instead of the user, so the user can no longer examine his own
process--in a case where there was never any privileged data to
protect. This affects e.g. auxv, environ, fd; in Fedora (execshield)
kernels, also maps. In practice, you can only notice this when a
debugger has requested PTRACE_EVENT_EXIT tracing.
set_dumpable was only used in do_coredump for synchronization and not
intended for any security purpose. (It doesn't secure anything that wasn't
already unsecured when a process dies by SIGTERM instead of SIGQUIT.)
This changes do_coredump to check the core_waiters count as the means of
synchronization, which is sufficient. Now we leave the "dumpable" bits alone.
Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 file changed