futex: Mark get_robust_list as deprecated

Notify get_robust_list users that the syscall is going away.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Cc: Darren Hart <dvhart@linux.intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Serge E. Hallyn <serge.hallyn@canonical.com>
Cc: kernel-hardening@lists.openwall.com
Cc: spender@grsecurity.net
Link: http://lkml.kernel.org/r/20120323190855.GA27213@www.outflux.net
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

3 files changed, 14 insertions, 0 deletions

diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt
index 0cad4803ffa..c1be8066ea5 100644
--- a/Documentation/feature-removal-schedule.txt
+++ b/Documentation/feature-removal-schedule.txt
@@ -529,3 +529,13 @@ When:	3.5
 Why:    The old kmap_atomic() with two arguments is deprecated, we only
         keep it for backward compatibility for few cycles and then drop it.
 Who:    Cong Wang <amwang@redhat.com>
+
+----------------------------
+
+What:   get_robust_list syscall
+When:   2013
+Why:    There appear to be no production users of the get_robust_list syscall,
+        and it runs the risk of leaking address locations, allowing the bypass
+        of ASLR. It was only ever intended for debugging, so it should be
+        removed.
+Who:    Kees Cook <keescook@chromium.org>
diff --git a/kernel/futex.c b/kernel/futex.c
index d701be57c42..e2b0fb9a0b3 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -2449,6 +2449,8 @@ SYSCALL_DEFINE3(get_robust_list, int, pid,
         if (!futex_cmpxchg_enabled)
                 return -ENOSYS;
 
+        WARN_ONCE(1, "deprecated: get_robust_list will be deleted in 2013.\n");
+
         rcu_read_lock();
 
         ret = -ESRCH;
diff --git a/kernel/futex_compat.c b/kernel/futex_compat.c
index a9642d52863..83e368b005f 100644
--- a/kernel/futex_compat.c
+++ b/kernel/futex_compat.c
@@ -142,6 +142,8 @@ compat_sys_get_robust_list(int pid, compat_uptr_t __user *head_ptr,
         if (!futex_cmpxchg_enabled)
                 return -ENOSYS;
 
+        WARN_ONCE(1, "deprecated: get_robust_list will be deleted in 2013.\n");
+
         rcu_read_lock();
 
         ret = -ESRCH;