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>

diff --git a/fs/proc/base.c b/fs/proc/base.c
index b9760628e1fde7b9a5c681798a65185144abeb92..a08c922893571b250ff7daf363b67f675a4483ed 100644 (file)
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2588,7 +2588,7 @@ static const struct pid_entry tgid_base_stuff[] = {
        REG("environ",    S_IRUSR, proc_environ_operations),
        INF("auxv",       S_IRUSR, proc_pid_auxv),
        ONE("status",     S_IRUGO, proc_pid_status),
-       ONE("personality", S_IRUGO, proc_pid_personality),
+       ONE("personality", S_IRUSR, proc_pid_personality),
        INF("limits",     S_IRUGO, proc_pid_limits),
 #ifdef CONFIG_SCHED_DEBUG
        REG("sched",      S_IRUGO|S_IWUSR, proc_pid_sched_operations),
@@ -2598,7 +2598,7 @@ static const struct pid_entry tgid_base_stuff[] = {
 #endif
        REG("comm",      S_IRUGO|S_IWUSR, proc_pid_set_comm_operations),
 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
-       INF("syscall",    S_IRUGO, proc_pid_syscall),
+       INF("syscall",    S_IRUSR, proc_pid_syscall),
 #endif
        INF("cmdline",    S_IRUGO, proc_pid_cmdline),
        ONE("stat",       S_IRUGO, proc_tgid_stat),
@@ -2626,7 +2626,7 @@ static const struct pid_entry tgid_base_stuff[] = {
        INF("wchan",      S_IRUGO, proc_pid_wchan),
 #endif
 #ifdef CONFIG_STACKTRACE
-       ONE("stack",      S_IRUGO, proc_pid_stack),
+       ONE("stack",      S_IRUSR, proc_pid_stack),
 #endif
 #ifdef CONFIG_SCHEDSTATS
        INF("schedstat",  S_IRUGO, proc_pid_schedstat),
@@ -2927,14 +2927,14 @@ static const struct pid_entry tid_base_stuff[] = {
        REG("environ",   S_IRUSR, proc_environ_operations),
        INF("auxv",      S_IRUSR, proc_pid_auxv),
        ONE("status",    S_IRUGO, proc_pid_status),
-       ONE("personality", S_IRUGO, proc_pid_personality),
+       ONE("personality", S_IRUSR, proc_pid_personality),
        INF("limits",    S_IRUGO, proc_pid_limits),
 #ifdef CONFIG_SCHED_DEBUG
        REG("sched",     S_IRUGO|S_IWUSR, proc_pid_sched_operations),
 #endif
        REG("comm",      S_IRUGO|S_IWUSR, proc_pid_set_comm_operations),
 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
-       INF("syscall",   S_IRUGO, proc_pid_syscall),
+       INF("syscall",   S_IRUSR, proc_pid_syscall),
 #endif
        INF("cmdline",   S_IRUGO, proc_pid_cmdline),
        ONE("stat",      S_IRUGO, proc_tid_stat),
@@ -2964,7 +2964,7 @@ static const struct pid_entry tid_base_stuff[] = {
        INF("wchan",     S_IRUGO, proc_pid_wchan),
 #endif
 #ifdef CONFIG_STACKTRACE
-       ONE("stack",      S_IRUGO, proc_pid_stack),
+       ONE("stack",      S_IRUSR, proc_pid_stack),
 #endif
 #ifdef CONFIG_SCHEDSTATS
        INF("schedstat", S_IRUGO, proc_pid_schedstat),