summaryrefslogtreecommitdiff
path: root/fs/proc/internal.h
diff options
context:
space:
mode:
authorOleg Nesterov <oleg@redhat.com>2014-10-09 22:25:26 (GMT)
committerLinus Torvalds <torvalds@linux-foundation.org>2014-10-10 02:25:48 (GMT)
commit29a40ace841cba9b661711f042d1821cdc4ad47c (patch)
treeb04f8e2de4a4fd8e19889c2adfaef02235c678ec /fs/proc/internal.h
parent5381e169e78405bd54256860f151596f5a887617 (diff)
downloadlinux-29a40ace841cba9b661711f042d1821cdc4ad47c.tar.xz
fs/proc/task_mmu.c: shift mm_access() from m_start() to proc_maps_open()
A simple test-case from Kirill Shutemov cat /proc/self/maps >/dev/null chmod +x /proc/self/net/packet exec /proc/self/net/packet makes lockdep unhappy, cat/exec take seq_file->lock + cred_guard_mutex in the opposite order. It's a false positive and probably we should not allow "chmod +x" on proc files. Still I think that we should avoid mm_access() and cred_guard_mutex in sys_read() paths, security checking should happen at open time. Besides, this doesn't even look right if the task changes its ->mm between m_stop() and m_start(). Add the new "mm_struct *mm" member into struct proc_maps_private and change proc_maps_open() to initialize it using proc_mem_open(). Change m_start() to use priv->mm if atomic_inc_not_zero(mm_users) succeeds or return NULL (eof) otherwise. The only complication is that proc_maps_open() users should additionally do mmdrop() in fop->release(), add the new proc_map_release() helper for that. Note: this is the user-visible change, if the task execs after open("maps") the new ->mm won't be visible via this file. I hope this is fine, and this matches /proc/pid/mem bahaviour. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Oleg Nesterov <oleg@redhat.com> Reported-by: "Kirill A. Shutemov" <kirill@shutemov.name> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Cyrill Gorcunov <gorcunov@openvz.org> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/proc/internal.h')
-rw-r--r--fs/proc/internal.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/fs/proc/internal.h b/fs/proc/internal.h
index 3c68556..d271828 100644
--- a/fs/proc/internal.h
+++ b/fs/proc/internal.h
@@ -270,6 +270,7 @@ extern int proc_remount(struct super_block *, int *, char *);
struct proc_maps_private {
struct pid *pid;
struct task_struct *task;
+ struct mm_struct *mm;
#ifdef CONFIG_MMU
struct vm_area_struct *tail_vma;
#endif