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| author | Otto Ebeling <otto.ebeling@iki.fi> | 2017-11-15 17:38:14 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-11-15 18:21:06 -0800 |
| commit | 313674661925ee265f16570c893ea13cb9e00b82 (patch) | |
| tree | 9b2a8326083499609054ebe315541eda8ea7e931 /mm/mempolicy.c | |
| parent | 7f0b5fb953e750a7410cc96c67a656d79db48bcb (diff) | |
| download | lwn-313674661925ee265f16570c893ea13cb9e00b82.tar.gz lwn-313674661925ee265f16570c893ea13cb9e00b82.zip | |
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/mempolicy.c')
| -rw-r--r-- | mm/mempolicy.c | 13 |
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)) { rcu_read_unlock(); err = -EPERM; goto out_put; |