path: root/mm
diff options
authorOtto Ebeling <otto.ebeling@iki.fi>2017-11-15 17:38:14 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-11-15 18:21:06 -0800
commit313674661925ee265f16570c893ea13cb9e00b82 (patch)
tree9b2a8326083499609054ebe315541eda8ea7e931 /mm
parent7f0b5fb953e750a7410cc96c67a656d79db48bcb (diff)
Unify migrate_pages and move_pages access checks
Commit 197e7e521384 ("Sanitize 'move_pages()' permission checks") fixed a security issue I reported in the move_pages syscall, and made it so that you can't act on set-uid processes unless you have the CAP_SYS_PTRACE capability. Unify the access check logic of migrate_pages to match the new behavior of move_pages. We discussed this a bit in the security@ list and thought it'd be good for consistency even though there's no evident security impact. The NUMA node access checks are left intact and require CAP_SYS_NICE as before. Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1710011830320.6333@lakka.kapsi.fi Signed-off-by: Otto Ebeling <otto.ebeling@iki.fi> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
1 files changed, 4 insertions, 9 deletions
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index a2af6d58a68f..dad166b736ba 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -85,6 +85,7 @@
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/compat.h>
+#include <linux/ptrace.h>
#include <linux/swap.h>
#include <linux/seq_file.h>
#include <linux/proc_fs.h>
@@ -1365,7 +1366,6 @@ SYSCALL_DEFINE4(migrate_pages, pid_t, pid, unsigned long, maxnode,
const unsigned long __user *, old_nodes,
const unsigned long __user *, new_nodes)
- const struct cred *cred = current_cred(), *tcred;
struct mm_struct *mm = NULL;
struct task_struct *task;
nodemask_t task_nodes;
@@ -1401,15 +1401,10 @@ SYSCALL_DEFINE4(migrate_pages, pid_t, pid, unsigned long, maxnode,
err = -EINVAL;
- * Check if this process has the right to modify the specified
- * process. The right exists if the process has administrative
- * capabilities, superuser privileges or the same
- * userid as the target process.
+ * Check if this process has the right to modify the specified process.
+ * Use the regular "ptrace_may_access()" checks.
- tcred = __task_cred(task);
- if (!uid_eq(cred->euid, tcred->suid) && !uid_eq(cred->euid, tcred->uid) &&
- !uid_eq(cred->uid, tcred->suid) && !uid_eq(cred->uid, tcred->uid) &&
- !capable(CAP_SYS_NICE)) {
+ if (!ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS)) {
err = -EPERM;
goto out_put;