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authorLinus Torvalds <torvalds@linux-foundation.org>2016-09-01 15:55:56 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-09-01 15:55:56 -0700
commit511a8cdb650544b7efd1bbccf7967d3153aee5f6 (patch)
tree9e97e173ca7fb552e4994dd527dcff396acfdcfb
parent7d1ce606a37922879cbe40a6122047827105a332 (diff)
parent5efc244346f9f338765da3d592f7947b0afdc4b5 (diff)
downloadlinux-511a8cdb650544b7efd1bbccf7967d3153aee5f6.tar.bz2
Merge branch 'stable-4.8' of git://git.infradead.org/users/pcmoore/audit
Pull audit fixes from Paul Moore: "Two small patches to fix some bugs with the audit-by-executable functionality we introduced back in v4.3 (both patches are marked for the stable folks)" * 'stable-4.8' of git://git.infradead.org/users/pcmoore/audit: audit: fix exe_file access in audit_exe_compare mm: introduce get_task_exe_file
-rw-r--r--fs/proc/base.c7
-rw-r--r--include/linux/mm.h1
-rw-r--r--kernel/audit_watch.c8
-rw-r--r--kernel/fork.c23
4 files changed, 30 insertions, 9 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 54e270262979..ac0df4dde823 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1556,18 +1556,13 @@ static const struct file_operations proc_pid_set_comm_operations = {
static int proc_exe_link(struct dentry *dentry, struct path *exe_path)
{
struct task_struct *task;
- struct mm_struct *mm;
struct file *exe_file;
task = get_proc_task(d_inode(dentry));
if (!task)
return -ENOENT;
- mm = get_task_mm(task);
+ exe_file = get_task_exe_file(task);
put_task_struct(task);
- if (!mm)
- return -ENOENT;
- exe_file = get_mm_exe_file(mm);
- mmput(mm);
if (exe_file) {
*exe_path = exe_file->f_path;
path_get(&exe_file->f_path);
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 08ed53eeedd5..ef815b9cd426 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2014,6 +2014,7 @@ extern void mm_drop_all_locks(struct mm_struct *mm);
extern void set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file);
extern struct file *get_mm_exe_file(struct mm_struct *mm);
+extern struct file *get_task_exe_file(struct task_struct *task);
extern bool may_expand_vm(struct mm_struct *, vm_flags_t, unsigned long npages);
extern void vm_stat_account(struct mm_struct *, vm_flags_t, long npages);
diff --git a/kernel/audit_watch.c b/kernel/audit_watch.c
index d6709eb70970..0d302a87f21b 100644
--- a/kernel/audit_watch.c
+++ b/kernel/audit_watch.c
@@ -19,6 +19,7 @@
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
+#include <linux/file.h>
#include <linux/kernel.h>
#include <linux/audit.h>
#include <linux/kthread.h>
@@ -544,10 +545,11 @@ int audit_exe_compare(struct task_struct *tsk, struct audit_fsnotify_mark *mark)
unsigned long ino;
dev_t dev;
- rcu_read_lock();
- exe_file = rcu_dereference(tsk->mm->exe_file);
+ exe_file = get_task_exe_file(tsk);
+ if (!exe_file)
+ return 0;
ino = exe_file->f_inode->i_ino;
dev = exe_file->f_inode->i_sb->s_dev;
- rcu_read_unlock();
+ fput(exe_file);
return audit_mark_compare(mark, ino, dev);
}
diff --git a/kernel/fork.c b/kernel/fork.c
index aaf782327bf3..36c0daa03c60 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -799,6 +799,29 @@ struct file *get_mm_exe_file(struct mm_struct *mm)
EXPORT_SYMBOL(get_mm_exe_file);
/**
+ * get_task_exe_file - acquire a reference to the task's executable file
+ *
+ * Returns %NULL if task's mm (if any) has no associated executable file or
+ * this is a kernel thread with borrowed mm (see the comment above get_task_mm).
+ * User must release file via fput().
+ */
+struct file *get_task_exe_file(struct task_struct *task)
+{
+ struct file *exe_file = NULL;
+ struct mm_struct *mm;
+
+ task_lock(task);
+ mm = task->mm;
+ if (mm) {
+ if (!(task->flags & PF_KTHREAD))
+ exe_file = get_mm_exe_file(mm);
+ }
+ task_unlock(task);
+ return exe_file;
+}
+EXPORT_SYMBOL(get_task_exe_file);
+
+/**
* get_task_mm - acquire a reference to the task's mm
*
* Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning