Merge branch 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszer...

[sfrench/cifs-2.6.git] / fs / overlayfs / copy_up.c

diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index 3f803b3a1f8295b9d9d3f903cc9f1198c6910f4a..aeb60f791418d6d6cba59f2dc743e8b8c71d5297 100644 (file)
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -57,6 +57,7 @@ int ovl_copy_xattr(struct dentry *old, struct dentry *new)
        ssize_t list_size, size, value_size = 0;
        char *buf, *name, *value = NULL;
        int uninitialized_var(error);
+       size_t slen;
 
        if (!(old->d_inode->i_opflags & IOP_XATTR) ||
            !(new->d_inode->i_opflags & IOP_XATTR))
@@ -79,7 +80,16 @@ int ovl_copy_xattr(struct dentry *old, struct dentry *new)
                goto out;
        }
 
-       for (name = buf; name < (buf + list_size); name += strlen(name) + 1) {
+       for (name = buf; list_size; name += slen) {
+               slen = strnlen(name, list_size) + 1;
+
+               /* underlying fs providing us with an broken xattr list? */
+               if (WARN_ON(slen > list_size)) {
+                       error = -EIO;
+                       break;
+               }
+               list_size -= slen;
+
                if (ovl_is_private_xattr(name))
                        continue;
 retry:
@@ -174,40 +184,6 @@ out_fput:
        return error;
 }
 
-static char *ovl_read_symlink(struct dentry *realdentry)
-{
-       int res;
-       char *buf;
-       struct inode *inode = realdentry->d_inode;
-       mm_segment_t old_fs;
-
-       res = -EINVAL;
-       if (!inode->i_op->readlink)
-               goto err;
-
-       res = -ENOMEM;
-       buf = (char *) __get_free_page(GFP_KERNEL);
-       if (!buf)
-               goto err;
-
-       old_fs = get_fs();
-       set_fs(get_ds());
-       /* The cast to a user pointer is valid due to the set_fs() */
-       res = inode->i_op->readlink(realdentry,
-                                   (char __user *)buf, PAGE_SIZE - 1);
-       set_fs(old_fs);
-       if (res < 0) {
-               free_page((unsigned long) buf);
-               goto err;
-       }
-       buf[res] = '\0';
-
-       return buf;
-
-err:
-       return ERR_PTR(res);
-}
-
 static int ovl_set_timestamps(struct dentry *upperdentry, struct kstat *stat)
 {
        struct iattr attr = {
@@ -354,19 +330,20 @@ out_cleanup:
 int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
                    struct path *lowerpath, struct kstat *stat)
 {
+       DEFINE_DELAYED_CALL(done);
        struct dentry *workdir = ovl_workdir(dentry);
        int err;
        struct kstat pstat;
        struct path parentpath;
+       struct dentry *lowerdentry = lowerpath->dentry;
        struct dentry *upperdir;
        struct dentry *upperdentry;
-       const struct cred *old_cred;
-       char *link = NULL;
+       const char *link = NULL;
 
        if (WARN_ON(!workdir))
                return -EROFS;
 
-       ovl_do_check_copy_up(lowerpath->dentry);
+       ovl_do_check_copy_up(lowerdentry);
 
        ovl_path_upper(parent, &parentpath);
        upperdir = parentpath.dentry;
@@ -376,13 +353,11 @@ int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
                return err;
 
        if (S_ISLNK(stat->mode)) {
-               link = ovl_read_symlink(lowerpath->dentry);
+               link = vfs_get_link(lowerdentry, &done);
                if (IS_ERR(link))
                        return PTR_ERR(link);
        }
 
-       old_cred = ovl_override_creds(dentry->d_sb);
-
        err = -EIO;
        if (lock_rename(workdir, upperdir) != NULL) {
                pr_err("overlayfs: failed to lock workdir+upperdir\n");
@@ -403,19 +378,16 @@ int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
        }
 out_unlock:
        unlock_rename(workdir, upperdir);
-       revert_creds(old_cred);
-
-       if (link)
-               free_page((unsigned long) link);
+       do_delayed_call(&done);
 
        return err;
 }
 
 int ovl_copy_up(struct dentry *dentry)
 {
-       int err;
+       int err = 0;
+       const struct cred *old_cred = ovl_override_creds(dentry->d_sb);
 
-       err = 0;
        while (!err) {
                struct dentry *next;
                struct dentry *parent;
@@ -447,6 +419,7 @@ int ovl_copy_up(struct dentry *dentry)
                dput(parent);
                dput(next);
        }
+       revert_creds(old_cred);
 
        return err;
 }