procfs: make /proc/*/{stack,syscall,personality} 0400
These procfs files contain sensitive information and currently their mode is 0444. Change this to 0400, so the VFS will be able to block unprivileged processes from getting file descriptors on arbitrary privileged /proc/*/{stack,syscall,personality} files. This reduces the scope of ASLR leaking and bypasses by protecting already running processes. Signed-off-by: Djalal Harouni <tixxdz@opendz.org> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Andy Lutomirski <luto@amacapital.net> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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