Fix f_flags/f_mode in case of lookup_instantiate_filp() from open(pathname, 3)

Just set f_flags when shoving struct file into nameidata; don't
postpone that until __dentry_open().  do_filp_open() has correct
value; lookup_instantiate_filp() doesn't - we lose the difference
between O_RDWR and 3 by that point.

We still set .intent.open.flags, so no fs code needs to be changed.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

3 files changed, 17 insertions, 9 deletions

diff --git a/fs/internal.h b/fs/internal.h
index f67cd141d9a8..e96a1667d749 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -85,3 +85,10 @@ extern struct file *get_empty_filp(void);
  * super.c
  */
 extern int do_remount_sb(struct super_block *, int, void *, int);
+
+/*
+ * open.c
+ */
+struct nameidata;
+extern struct file *nameidata_to_filp(struct nameidata *);
+extern void release_open_intent(struct nameidata *);
diff --git a/fs/namei.c b/fs/namei.c
index dad4b80257db..d517f73aa36b 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1640,6 +1640,7 @@ struct file *do_filp_open(int dfd, const char *pathname,
                 if (filp == NULL)
                         return ERR_PTR(-ENFILE);
                 nd.intent.open.file = filp;
+                filp->f_flags = open_flag;
                 nd.intent.open.flags = flag;
                 nd.intent.open.create_mode = 0;
                 error = do_path_lookup(dfd, pathname,
@@ -1685,6 +1686,7 @@ struct file *do_filp_open(int dfd, const char *pathname,
         if (filp == NULL)
                 goto exit_parent;
         nd.intent.open.file = filp;
+        filp->f_flags = open_flag;
         nd.intent.open.flags = flag;
         nd.intent.open.create_mode = mode;
         dir = nd.path.dentry;
@@ -1725,7 +1727,7 @@ do_last:
                         mnt_drop_write(nd.path.mnt);
                         goto exit;
                 }
-                filp = nameidata_to_filp(&nd, open_flag);
+                filp = nameidata_to_filp(&nd);
                 mnt_drop_write(nd.path.mnt);
                 if (nd.root.mnt)
                         path_put(&nd.root);
@@ -1789,7 +1791,7 @@ ok:
                         mnt_drop_write(nd.path.mnt);
                 goto exit;
         }
-        filp = nameidata_to_filp(&nd, open_flag);
+        filp = nameidata_to_filp(&nd);
         if (!IS_ERR(filp)) {
                 error = ima_path_check(&filp->f_path, filp->f_mode &
                                (MAY_READ | MAY_WRITE | MAY_EXEC));
diff --git a/fs/open.c b/fs/open.c
index ca69241796bd..6daee28f6e8f 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -821,15 +821,14 @@ static inline int __get_file_write_access(struct inode *inode,
 }
 
 static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
-                                        int flags, struct file *f,
+                                        struct file *f,
                                         int (*open)(struct inode *, struct file *),
                                         const struct cred *cred)
 {
         struct inode *inode;
         int error;
 
-        f->f_flags = flags;
-        f->f_mode = (__force fmode_t)((flags+1) & O_ACCMODE) | FMODE_LSEEK |
+        f->f_mode = (__force fmode_t)((f->f_flags+1) & O_ACCMODE) | FMODE_LSEEK |
                                 FMODE_PREAD | FMODE_PWRITE;
         inode = dentry->d_inode;
         if (f->f_mode & FMODE_WRITE) {
@@ -930,7 +929,6 @@ struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry
         if (IS_ERR(dentry))
                 goto out_err;
         nd->intent.open.file = __dentry_open(dget(dentry), mntget(nd->path.mnt),
-                                             nd->intent.open.flags - 1,
                                              nd->intent.open.file,
                                              open, cred);
 out:
@@ -949,7 +947,7 @@ EXPORT_SYMBOL_GPL(lookup_instantiate_filp);
  *
  * Note that this function destroys the original nameidata
  */
-struct file *nameidata_to_filp(struct nameidata *nd, int flags)
+struct file *nameidata_to_filp(struct nameidata *nd)
 {
         const struct cred *cred = current_cred();
         struct file *filp;
@@ -958,7 +956,7 @@ struct file *nameidata_to_filp(struct nameidata *nd, int flags)
         filp = nd->intent.open.file;
         /* Has the filesystem initialised the file for us? */
         if (filp->f_path.dentry == NULL)
-                filp = __dentry_open(nd->path.dentry, nd->path.mnt, flags, filp,
+                filp = __dentry_open(nd->path.dentry, nd->path.mnt, filp,
                                      NULL, cred);
         else
                 path_put(&nd->path);
@@ -997,7 +995,8 @@ struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags,
                 return ERR_PTR(error);
         }
 
-        return __dentry_open(dentry, mnt, flags, f, NULL, cred);
+        f->f_flags = flags;
+        return __dentry_open(dentry, mnt, f, NULL, cred);
 }
 EXPORT_SYMBOL(dentry_open);