locks: fix locks_mandatory_locked to respect file-private locks
As Trond pointed out, you can currently deadlock yourself by setting a
file-private lock on a file that requires mandatory locking and then
trying to do I/O on it.
Avoid this problem by plumbing some knowledge of file-private locks into
the mandatory locking code. In order to do this, we must pass down
information about the struct file that's being used to
locks_verify_locked.
Reported-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Acked-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/locks.c b/fs/locks.c
index 09d6c8c..d82c51c 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -1155,13 +1155,14 @@
/**
* locks_mandatory_locked - Check for an active lock
- * @inode: the file to check
+ * @file: the file to check
*
* Searches the inode's list of locks to find any POSIX locks which conflict.
* This function is called from locks_verify_locked() only.
*/
-int locks_mandatory_locked(struct inode *inode)
+int locks_mandatory_locked(struct file *file)
{
+ struct inode *inode = file_inode(file);
fl_owner_t owner = current->files;
struct file_lock *fl;
@@ -1172,7 +1173,7 @@
for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
if (!IS_POSIX(fl))
continue;
- if (fl->fl_owner != owner)
+ if (fl->fl_owner != owner && fl->fl_owner != (fl_owner_t)file)
break;
}
spin_unlock(&inode->i_lock);
diff --git a/fs/namei.c b/fs/namei.c
index d580df2..dc51bac 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2542,7 +2542,7 @@
/*
* Refuse to truncate files with mandatory locks held on them.
*/
- error = locks_verify_locked(inode);
+ error = locks_verify_locked(filp);
if (!error)
error = security_path_truncate(path);
if (!error) {
diff --git a/include/linux/fs.h b/include/linux/fs.h
index ae91dce..4aa81e6 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1912,6 +1912,11 @@
extern void ihold(struct inode * inode);
extern void iput(struct inode *);
+static inline struct inode *file_inode(struct file *f)
+{
+ return f->f_inode;
+}
+
/* /sys/fs */
extern struct kobject *fs_kobj;
@@ -1921,7 +1926,7 @@
#define FLOCK_VERIFY_WRITE 2
#ifdef CONFIG_FILE_LOCKING
-extern int locks_mandatory_locked(struct inode *);
+extern int locks_mandatory_locked(struct file *);
extern int locks_mandatory_area(int, struct inode *, struct file *, loff_t, size_t);
/*
@@ -1944,10 +1949,10 @@
return IS_MANDLOCK(ino) && __mandatory_lock(ino);
}
-static inline int locks_verify_locked(struct inode *inode)
+static inline int locks_verify_locked(struct file *file)
{
- if (mandatory_lock(inode))
- return locks_mandatory_locked(inode);
+ if (mandatory_lock(file_inode(file)))
+ return locks_mandatory_locked(file);
return 0;
}
@@ -2008,7 +2013,7 @@
}
#else /* !CONFIG_FILE_LOCKING */
-static inline int locks_mandatory_locked(struct inode *inode)
+static inline int locks_mandatory_locked(struct file *file)
{
return 0;
}
@@ -2030,7 +2035,7 @@
return 0;
}
-static inline int locks_verify_locked(struct inode *inode)
+static inline int locks_verify_locked(struct file *file)
{
return 0;
}
@@ -2297,11 +2302,6 @@
return (inode->i_mode & S_IXUGO) || S_ISDIR(inode->i_mode);
}
-static inline struct inode *file_inode(struct file *f)
-{
- return f->f_inode;
-}
-
static inline void file_start_write(struct file *file)
{
if (!S_ISREG(file_inode(file)->i_mode))
diff --git a/mm/mmap.c b/mm/mmap.c
index 20ff0c3..5932ce9 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1299,7 +1299,7 @@
/*
* Make sure there are no mandatory locks on the file.
*/
- if (locks_verify_locked(inode))
+ if (locks_verify_locked(file))
return -EAGAIN;
vm_flags |= VM_SHARED | VM_MAYSHARE;
diff --git a/mm/nommu.c b/mm/nommu.c
index 8740213..a554e5a 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -995,7 +995,7 @@
(file->f_mode & FMODE_WRITE))
return -EACCES;
- if (locks_verify_locked(file_inode(file)))
+ if (locks_verify_locked(file))
return -EAGAIN;
if (!(capabilities & BDI_CAP_MAP_DIRECT))
