Merge tag 'pull-revalidate' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull vfs d_revalidate updates from Al Viro:
 "Provide stable parent and name to ->d_revalidate() instances

  Most of the filesystem methods where we care about dentry name and
  parent have their stability guaranteed by the callers;
  ->d_revalidate() is the major exception.

  It's easy enough for callers to supply stable values for expected name
  and expected parent of the dentry being validated. That kills quite a
  bit of boilerplate in ->d_revalidate() instances, along with a bunch
  of races where they used to access ->d_name without sufficient
  precautions"

* tag 'pull-revalidate' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  9p: fix ->rename_sem exclusion
  orangefs_d_revalidate(): use stable parent inode and name passed by caller
  ocfs2_dentry_revalidate(): use stable parent inode and name passed by caller
  nfs: fix ->d_revalidate() UAF on ->d_name accesses
  nfs{,4}_lookup_validate(): use stable parent inode passed by caller
  gfs2_drevalidate(): use stable parent inode and name passed by caller
  fuse_dentry_revalidate(): use stable parent inode and name passed by caller
  vfat_revalidate{,_ci}(): use stable parent inode passed by caller
  exfat_d_revalidate(): use stable parent inode passed by caller
  fscrypt_d_revalidate(): use stable parent inode passed by caller
  ceph_d_revalidate(): propagate stable name down into request encoding
  ceph_d_revalidate(): use stable parent inode passed by caller
  afs_d_revalidate(): use stable name and parent inode passed by caller
  Pass parent directory inode and expected name to ->d_revalidate()
  generic_ci_d_compare(): use shortname_storage
  ext4 fast_commit: make use of name_snapshot primitives
  dissolve external_name.u into separate members
  make take_dentry_name_snapshot() lockless
  dcache: back inline names with a struct-wrapped array of unsigned long
  make sure that DNAME_INLINE_LEN is a multiple of word size

1 files changed, 12 insertions, 28 deletions

diff --git a/fs/afs/dir.c b/fs/afs/dir.c
index a843c36fc471..02cbf38e1a77 100644
--- a/fs/afs/dir.c
+++ b/fs/afs/dir.c
@@ -23,7 +23,8 @@ static struct dentry *afs_lookup(struct inode *dir, struct dentry *dentry,
 				 unsigned int flags);
 static int afs_dir_open(struct inode *inode, struct file *file);
 static int afs_readdir(struct file *file, struct dir_context *ctx);
-static int afs_d_revalidate(struct dentry *dentry, unsigned int flags);
+static int afs_d_revalidate(struct inode *dir, const struct qstr *name,
+			    struct dentry *dentry, unsigned int flags);
 static int afs_d_delete(const struct dentry *dentry);
 static void afs_d_iput(struct dentry *dentry, struct inode *inode);
 static bool afs_lookup_one_filldir(struct dir_context *ctx, const char *name, int nlen,
@@ -597,19 +598,19 @@ static bool afs_lookup_one_filldir(struct dir_context *ctx, const char *name,
  * Do a lookup of a single name in a directory
  * - just returns the FID the dentry name maps to if found
  */
-static int afs_do_lookup_one(struct inode *dir, struct dentry *dentry,
+static int afs_do_lookup_one(struct inode *dir, const struct qstr *name,
 			     struct afs_fid *fid,
 			     afs_dataversion_t *_dir_version)
 {
 	struct afs_super_info *as = dir->i_sb->s_fs_info;
 	struct afs_lookup_one_cookie cookie = {
 		.ctx.actor = afs_lookup_one_filldir,
-		.name = dentry->d_name,
+		.name = *name,
 		.fid.vid = as->volume->vid
 	};
 	int ret;
 
-	_enter("{%lu},%p{%pd},", dir->i_ino, dentry, dentry);
+	_enter("{%lu},{%.*s},", dir->i_ino, name->len, name->name);
 
 	/* search the directory */
 	ret = afs_dir_iterate(dir, &cookie.ctx, NULL, _dir_version);
@@ -1023,21 +1024,12 @@ static struct dentry *afs_lookup(struct inode *dir, struct dentry *dentry,
 /*
  * Check the validity of a dentry under RCU conditions.
  */
-static int afs_d_revalidate_rcu(struct dentry *dentry)
+static int afs_d_revalidate_rcu(struct afs_vnode *dvnode, struct dentry *dentry)
 {
-	struct afs_vnode *dvnode;
-	struct dentry *parent;
-	struct inode *dir;
 	long dir_version, de_version;
 
 	_enter("%p", dentry);
 
-	/* Check the parent directory is still valid first. */
-	parent = READ_ONCE(dentry->d_parent);
-	dir = d_inode_rcu(parent);
-	if (!dir)
-		return -ECHILD;
-	dvnode = AFS_FS_I(dir);
 	if (test_bit(AFS_VNODE_DELETED, &dvnode->flags))
 		return -ECHILD;
 
@@ -1065,11 +1057,11 @@ static int afs_d_revalidate_rcu(struct dentry *dentry)
  * - NOTE! the hit can be a negative hit too, so we can't assume we have an
  *   inode
  */
-static int afs_d_revalidate(struct dentry *dentry, unsigned int flags)
+static int afs_d_revalidate(struct inode *parent_dir, const struct qstr *name,
+			    struct dentry *dentry, unsigned int flags)
 {
-	struct afs_vnode *vnode, *dir;
+	struct afs_vnode *vnode, *dir = AFS_FS_I(parent_dir);
 	struct afs_fid fid;
-	struct dentry *parent;
 	struct inode *inode;
 	struct key *key;
 	afs_dataversion_t dir_version, invalid_before;
@@ -1077,7 +1069,7 @@ static int afs_d_revalidate(struct dentry *dentry, unsigned int flags)
 	int ret;
 
 	if (flags & LOOKUP_RCU)
-		return afs_d_revalidate_rcu(dentry);
+		return afs_d_revalidate_rcu(dir, dentry);
 
 	if (d_really_is_positive(dentry)) {
 		vnode = AFS_FS_I(d_inode(dentry));
@@ -1092,14 +1084,9 @@ static int afs_d_revalidate(struct dentry *dentry, unsigned int flags)
 	if (IS_ERR(key))
 		key = NULL;
 
-	/* Hold the parent dentry so we can peer at it */
-	parent = dget_parent(dentry);
-	dir = AFS_FS_I(d_inode(parent));
-
 	/* validate the parent directory */
 	ret = afs_validate(dir, key);
 	if (ret == -ERESTARTSYS) {
-		dput(parent);
 		key_put(key);
 		return ret;
 	}
@@ -1127,7 +1114,7 @@ static int afs_d_revalidate(struct dentry *dentry, unsigned int flags)
 	afs_stat_v(dir, n_reval);
 
 	/* search the directory for this vnode */
-	ret = afs_do_lookup_one(&dir->netfs.inode, dentry, &fid, &dir_version);
+	ret = afs_do_lookup_one(&dir->netfs.inode, name, &fid, &dir_version);
 	switch (ret) {
 	case 0:
 		/* the filename maps to something */
@@ -1171,22 +1158,19 @@ static int afs_d_revalidate(struct dentry *dentry, unsigned int flags)
 		goto out_valid;
 
 	default:
-		_debug("failed to iterate dir %pd: %d",
-		       parent, ret);
+		_debug("failed to iterate parent %pd2: %d", dentry, ret);
 		goto not_found;
 	}
 
 out_valid:
 	dentry->d_fsdata = (void *)(unsigned long)dir_version;
 out_valid_noupdate:
-	dput(parent);
 	key_put(key);
 	_leave(" = 1 [valid]");
 	return 1;
 
 not_found:
 	_debug("dropping dentry %pd2", dentry);
-	dput(parent);
 	key_put(key);
 
 	_leave(" = 0 [bad]");