pid-namespaces-vs-locks-interaction

fcntl(F_GETLK,..) can return pid of process for not current pid namespace
(if process is belonged to the several namespaces).  It is true also for
pids in /proc/locks.  So correct behavior is saving pointer to the struct
pid of the process lock owner.

Signed-off-by: Vitaliy Gusev <vgusev@openvz.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

2 files changed, 24 insertions, 6 deletions

diff --git a/fs/locks.c b/fs/locks.c
index faddccb6336a..49354b9c7dc1 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -125,6 +125,7 @@
 #include <linux/syscalls.h>
 #include <linux/time.h>
 #include <linux/rcupdate.h>
+#include <linux/pid_namespace.h>
 
 #include <asm/semaphore.h>
 #include <asm/uaccess.h>
@@ -185,6 +186,7 @@ void locks_init_lock(struct file_lock *fl)
         fl->fl_fasync = NULL;
         fl->fl_owner = NULL;
         fl->fl_pid = 0;
+        fl->fl_nspid = NULL;
         fl->fl_file = NULL;
         fl->fl_flags = 0;
         fl->fl_type = 0;
@@ -553,6 +555,8 @@ static void locks_insert_lock(struct file_lock **pos, struct file_lock *fl)
 {
         list_add(&fl->fl_link, &file_lock_list);
 
+        fl->fl_nspid = get_pid(task_tgid(current));
+
         /* insert into file's list */
         fl->fl_next = *pos;
         *pos = fl;
@@ -584,6 +588,11 @@ static void locks_delete_lock(struct file_lock **thisfl_p)
         if (fl->fl_ops && fl->fl_ops->fl_remove)
                 fl->fl_ops->fl_remove(fl);
 
+        if (fl->fl_nspid) {
+                put_pid(fl->fl_nspid);
+                fl->fl_nspid = NULL;
+        }
+
         locks_wake_up_blocks(fl);
         locks_free_lock(fl);
 }
@@ -646,14 +655,16 @@ posix_test_lock(struct file *filp, struct file_lock *fl)
                 if (posix_locks_conflict(fl, cfl))
                         break;
         }
-        if (cfl)
+        if (cfl) {
                 __locks_copy_lock(fl, cfl);
-        else
+                if (cfl->fl_nspid)
+                        fl->fl_pid = pid_nr_ns(cfl->fl_nspid,
+                                                task_active_pid_ns(current));
+        } else
                 fl->fl_type = F_UNLCK;
         unlock_kernel();
         return;
 }
-
 EXPORT_SYMBOL(posix_test_lock);
 
 /*
@@ -2070,6 +2081,12 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl,
                                                         int id, char *pfx)
 {
         struct inode *inode = NULL;
+        unsigned int fl_pid;
+
+        if (fl->fl_nspid)
+                fl_pid = pid_nr_ns(fl->fl_nspid, task_active_pid_ns(current));
+        else
+                fl_pid = fl->fl_pid;
 
         if (fl->fl_file != NULL)
                 inode = fl->fl_file->f_path.dentry->d_inode;
@@ -2110,16 +2127,16 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl,
         }
         if (inode) {
 #ifdef WE_CAN_BREAK_LSLK_NOW
-                seq_printf(f, "%d %s:%ld ", fl->fl_pid,
+                seq_printf(f, "%d %s:%ld ", fl_pid,
                                 inode->i_sb->s_id, inode->i_ino);
 #else
                 /* userspace relies on this representation of dev_t ;-( */
-                seq_printf(f, "%d %02x:%02x:%ld ", fl->fl_pid,
+                seq_printf(f, "%d %02x:%02x:%ld ", fl_pid,
                                 MAJOR(inode->i_sb->s_dev),
                                 MINOR(inode->i_sb->s_dev), inode->i_ino);
 #endif
         } else {
-                seq_printf(f, "%d <none>:0 ", fl->fl_pid);
+                seq_printf(f, "%d <none>:0 ", fl_pid);
         }
         if (IS_POSIX(fl)) {
                 if (fl->fl_end == OFFSET_MAX)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index a516b6716870..b7736ab8bb5e 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -872,6 +872,7 @@ struct file_lock {
         struct list_head fl_block;      /* circular list of blocked processes */
         fl_owner_t fl_owner;
         unsigned int fl_pid;
+        struct pid *fl_nspid;
         wait_queue_head_t fl_wait;
         struct file *fl_file;
         unsigned char fl_flags;