Merge tag 'fscrypt_for_linus' of git://git.kernel.org/pub/scm/fs/fscrypt/fscrypt

Pull fscrypt updates from Ted Ts'o:
 "Clean up fscrypt's dcache revalidation support, and other
  miscellaneous cleanups"

* tag 'fscrypt_for_linus' of git://git.kernel.org/pub/scm/fs/fscrypt/fscrypt:
  fscrypt: cache decrypted symlink target in ->i_link
  vfs: use READ_ONCE() to access ->i_link
  fscrypt: fix race where ->lookup() marks plaintext dentry as ciphertext
  fscrypt: only set dentry_operations on ciphertext dentries
  fs, fscrypt: clear DCACHE_ENCRYPTED_NAME when unaliasing directory
  fscrypt: fix race allowing rename() and link() of ciphertext dentries
  fscrypt: clean up and improve dentry revalidation
  fscrypt: use READ_ONCE() to access ->i_crypt_info
  fscrypt: remove WARN_ON_ONCE() when decryption fails
  fscrypt: drop inode argument from fscrypt_get_ctx()

fs/crypto/bio.c

@@ -36,12 +36,10 @@ static void __fscrypt_decrypt_bio(struct bio *bio, bool done)
 		int ret = fscrypt_decrypt_page(page->mapping->host, page,
 				PAGE_SIZE, 0, page->index);
 
-		if (ret) {
-			WARN_ON_ONCE(1);
+		if (ret)
 			SetPageError(page);
-		} else if (done) {
+		else if (done)
 			SetPageUptodate(page);
-		}
 		if (done)
 			unlock_page(page);
 	}
@@ -103,7 +101,7 @@ int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
 
 	BUG_ON(inode->i_sb->s_blocksize != PAGE_SIZE);
 
-	ctx = fscrypt_get_ctx(inode, GFP_NOFS);
+	ctx = fscrypt_get_ctx(GFP_NOFS);
 	if (IS_ERR(ctx))
 		return PTR_ERR(ctx);
 

fs/crypto/crypto.c

@@ -87,23 +87,17 @@ EXPORT_SYMBOL(fscrypt_release_ctx);
 
 /**
  * fscrypt_get_ctx() - Gets an encryption context
- * @inode:       The inode for which we are doing the crypto
  * @gfp_flags:   The gfp flag for memory allocation
  *
  * Allocates and initializes an encryption context.
  *
- * Return: An allocated and initialized encryption context on success; error
- * value or NULL otherwise.
+ * Return: A new encryption context on success; an ERR_PTR() otherwise.
  */
-struct fscrypt_ctx *fscrypt_get_ctx(const struct inode *inode, gfp_t gfp_flags)
+struct fscrypt_ctx *fscrypt_get_ctx(gfp_t gfp_flags)
 {
-	struct fscrypt_ctx *ctx = NULL;
-	struct fscrypt_info *ci = inode->i_crypt_info;
+	struct fscrypt_ctx *ctx;
 	unsigned long flags;
 
-	if (ci == NULL)
-		return ERR_PTR(-ENOKEY);
-
 	/*
 	 * We first try getting the ctx from a free list because in
 	 * the common case the ctx will have an allocated and
@@ -258,9 +252,9 @@ struct page *fscrypt_encrypt_page(const struct inode *inode,
 
 	BUG_ON(!PageLocked(page));
 
-	ctx = fscrypt_get_ctx(inode, gfp_flags);
+	ctx = fscrypt_get_ctx(gfp_flags);
 	if (IS_ERR(ctx))
-		return (struct page *)ctx;
+		return ERR_CAST(ctx);
 
 	/* The encryption operation will require a bounce page. */
 	ciphertext_page = fscrypt_alloc_bounce_page(ctx, gfp_flags);
@@ -313,45 +307,47 @@ int fscrypt_decrypt_page(const struct inode *inode, struct page *page,
 EXPORT_SYMBOL(fscrypt_decrypt_page);
 
 /*
- * Validate dentries for encrypted directories to make sure we aren't
- * potentially caching stale data after a key has been added or
- * removed.
+ * Validate dentries in encrypted directories to make sure we aren't potentially
+ * caching stale dentries after a key has been added.
  */
 static int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags)
 {
 	struct dentry *dir;
-	int dir_has_key, cached_with_key;
+	int err;
+	int valid;
+
+	/*
+	 * Plaintext names are always valid, since fscrypt doesn't support
+	 * reverting to ciphertext names without evicting the directory's inode
+	 * -- which implies eviction of the dentries in the directory.
+	 */
+	if (!(dentry->d_flags & DCACHE_ENCRYPTED_NAME))
+		return 1;
+
+	/*
+	 * Ciphertext name; valid if the directory's key is still unavailable.
+	 *
+	 * Although fscrypt forbids rename() on ciphertext names, we still must
+	 * use dget_parent() here rather than use ->d_parent directly.  That's
+	 * because a corrupted fs image may contain directory hard links, which
+	 * the VFS handles by moving the directory's dentry tree in the dcache
+	 * each time ->lookup() finds the directory and it already has a dentry
+	 * elsewhere.  Thus ->d_parent can be changing, and we must safely grab
+	 * a reference to some ->d_parent to prevent it from being freed.
+	 */
 
 	if (flags & LOOKUP_RCU)
 		return -ECHILD;
 
 	dir = dget_parent(dentry);
-	if (!IS_ENCRYPTED(d_inode(dir))) {
+	err = fscrypt_get_encryption_info(d_inode(dir));
+	valid = !fscrypt_has_encryption_key(d_inode(dir));
 	dput(dir);
-		return 0;
-	}
 
-	spin_lock(&dentry->d_lock);
-	cached_with_key = dentry->d_flags & DCACHE_ENCRYPTED_WITH_KEY;
-	spin_unlock(&dentry->d_lock);
-	dir_has_key = (d_inode(dir)->i_crypt_info != NULL);
-	dput(dir);
+	if (err < 0)
+		return err;
 
-	/*
-	 * If the dentry was cached without the key, and it is a
-	 * negative dentry, it might be a valid name.  We can't check
-	 * if the key has since been made available due to locking
-	 * reasons, so we fail the validation so ext4_lookup() can do
-	 * this check.
-	 *
-	 * We also fail the validation if the dentry was created with
-	 * the key present, but we no longer have the key, or vice versa.
-	 */
-	if ((!cached_with_key && d_is_negative(dentry)) ||
-			(!cached_with_key && dir_has_key) ||
-			(cached_with_key && !dir_has_key))
-		return 0;
-	return 1;
+	return valid;
 }
 
 const struct dentry_operations fscrypt_d_ops = {

fs/crypto/fname.c

@@ -269,7 +269,7 @@ int fscrypt_fname_disk_to_usr(struct inode *inode,
 	if (iname->len < FS_CRYPTO_BLOCK_SIZE)
 		return -EUCLEAN;
 
-	if (inode->i_crypt_info)
+	if (fscrypt_has_encryption_key(inode))
 		return fname_decrypt(inode, iname, oname);
 
 	if (iname->len <= FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE) {
@@ -336,7 +336,7 @@ int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname,
 	if (ret)
 		return ret;
 
-	if (dir->i_crypt_info) {
+	if (fscrypt_has_encryption_key(dir)) {
 		if (!fscrypt_fname_encrypted_size(dir, iname->len,
 						  dir->i_sb->s_cop->max_namelen,
 						  &fname->crypto_buf.len))
@@ -356,6 +356,7 @@ int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname,
 	}
 	if (!lookup)
 		return -ENOKEY;
+	fname->is_ciphertext_name = true;
 
 	/*
 	 * We don't have the key and we are doing a lookup; decode the

fs/crypto/hooks.c

@@ -49,7 +49,8 @@ int fscrypt_file_open(struct inode *inode, struct file *filp)
 }
 EXPORT_SYMBOL_GPL(fscrypt_file_open);
 
-int __fscrypt_prepare_link(struct inode *inode, struct inode *dir)
+int __fscrypt_prepare_link(struct inode *inode, struct inode *dir,
+			   struct dentry *dentry)
 {
 	int err;
 
@@ -57,6 +58,10 @@ int __fscrypt_prepare_link(struct inode *inode, struct inode *dir)
 	if (err)
 		return err;
 
+	/* ... in case we looked up ciphertext name before key was added */
+	if (dentry->d_flags & DCACHE_ENCRYPTED_NAME)
+		return -ENOKEY;
+
 	if (!fscrypt_has_permitted_context(dir, inode))
 		return -EXDEV;
 
@@ -78,6 +83,11 @@ int __fscrypt_prepare_rename(struct inode *old_dir, struct dentry *old_dentry,
 	if (err)
 		return err;
 
+	/* ... in case we looked up ciphertext name(s) before key was added */
+	if ((old_dentry->d_flags | new_dentry->d_flags) &
+	    DCACHE_ENCRYPTED_NAME)
+		return -ENOKEY;
+
 	if (old_dir != new_dir) {
 		if (IS_ENCRYPTED(new_dir) &&
 		    !fscrypt_has_permitted_context(new_dir,
@@ -94,21 +104,21 @@ int __fscrypt_prepare_rename(struct inode *old_dir, struct dentry *old_dentry,
 }
 EXPORT_SYMBOL_GPL(__fscrypt_prepare_rename);
 
-int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry)
+int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry,
+			     struct fscrypt_name *fname)
 {
-	int err = fscrypt_get_encryption_info(dir);
+	int err = fscrypt_setup_filename(dir, &dentry->d_name, 1, fname);
 
-	if (err)
+	if (err && err != -ENOENT)
 		return err;
 
-	if (fscrypt_has_encryption_key(dir)) {
+	if (fname->is_ciphertext_name) {
 		spin_lock(&dentry->d_lock);
-		dentry->d_flags |= DCACHE_ENCRYPTED_WITH_KEY;
+		dentry->d_flags |= DCACHE_ENCRYPTED_NAME;
 		spin_unlock(&dentry->d_lock);
-	}
-
 		d_set_d_op(dentry, &fscrypt_d_ops);
-	return 0;
+	}
+	return err;
 }
 EXPORT_SYMBOL_GPL(__fscrypt_prepare_lookup);
 
@@ -179,11 +189,9 @@ int __fscrypt_encrypt_symlink(struct inode *inode, const char *target,
 	sd->len = cpu_to_le16(ciphertext_len);
 
 	err = fname_encrypt(inode, &iname, sd->encrypted_path, ciphertext_len);
-	if (err) {
-		if (!disk_link->name)
-			kfree(sd);
-		return err;
-	}
+	if (err)
+		goto err_free_sd;
+
 	/*
 	 * Null-terminating the ciphertext doesn't make sense, but we still
 	 * count the null terminator in the length, so we might as well
@@ -191,9 +199,20 @@ int __fscrypt_encrypt_symlink(struct inode *inode, const char *target,
 	 */
 	sd->encrypted_path[ciphertext_len] = '\0';
 
+	/* Cache the plaintext symlink target for later use by get_link() */
+	err = -ENOMEM;
+	inode->i_link = kmemdup(target, len + 1, GFP_NOFS);
+	if (!inode->i_link)
+		goto err_free_sd;
+
 	if (!disk_link->name)
 		disk_link->name = (unsigned char *)sd;
 	return 0;
+
+err_free_sd:
+	if (!disk_link->name)
+		kfree(sd);
+	return err;
 }
 EXPORT_SYMBOL_GPL(__fscrypt_encrypt_symlink);
 
@@ -202,7 +221,7 @@ EXPORT_SYMBOL_GPL(__fscrypt_encrypt_symlink);
  * @inode: the symlink inode
  * @caddr: the on-disk contents of the symlink
  * @max_size: size of @caddr buffer
- * @done: if successful, will be set up to free the returned target
+ * @done: if successful, will be set up to free the returned target if needed
  *
  * If the symlink's encryption key is available, we decrypt its target.
  * Otherwise, we encode its target for presentation.
@@ -217,12 +236,18 @@ const char *fscrypt_get_symlink(struct inode *inode, const void *caddr,
 {
 	const struct fscrypt_symlink_data *sd;
 	struct fscrypt_str cstr, pstr;
+	bool has_key;
 	int err;
 
 	/* This is for encrypted symlinks only */
 	if (WARN_ON(!IS_ENCRYPTED(inode)))
 		return ERR_PTR(-EINVAL);
 
+	/* If the decrypted target is already cached, just return it. */
+	pstr.name = READ_ONCE(inode->i_link);
+	if (pstr.name)
+		return pstr.name;
+
 	/*
 	 * Try to set up the symlink's encryption key, but we can continue
 	 * regardless of whether the key is available or not.
@@ -230,6 +255,7 @@ const char *fscrypt_get_symlink(struct inode *inode, const void *caddr,
 	err = fscrypt_get_encryption_info(inode);
 	if (err)
 		return ERR_PTR(err);
+	has_key = fscrypt_has_encryption_key(inode);
 
 	/*
 	 * For historical reasons, encrypted symlink targets are prefixed with
@@ -261,7 +287,17 @@ const char *fscrypt_get_symlink(struct inode *inode, const void *caddr,
 		goto err_kfree;
 
 	pstr.name[pstr.len] = '\0';
+
+	/*
+	 * Cache decrypted symlink targets in i_link for later use.  Don't cache
+	 * symlink targets encoded without the key, since those become outdated
+	 * once the key is added.  This pairs with the READ_ONCE() above and in
+	 * the VFS path lookup code.
+	 */
+	if (!has_key ||
+	    cmpxchg_release(&inode->i_link, NULL, pstr.name) != NULL)
 		set_delayed_call(done, kfree_link, pstr.name);
+
 	return pstr.name;
 
 err_kfree:

fs/crypto/keyinfo.c

@@ -508,7 +508,7 @@ int fscrypt_get_encryption_info(struct inode *inode)
 	u8 *raw_key = NULL;
 	int res;
 
-	if (inode->i_crypt_info)
+	if (fscrypt_has_encryption_key(inode))
 		return 0;
 
 	res = fscrypt_initialize(inode->i_sb->s_cop->flags);
@@ -572,7 +572,7 @@ int fscrypt_get_encryption_info(struct inode *inode)
 	if (res)
 		goto out;
 
-	if (cmpxchg(&inode->i_crypt_info, NULL, crypt_info) == NULL)
+	if (cmpxchg_release(&inode->i_crypt_info, NULL, crypt_info) == NULL)
 		crypt_info = NULL;
 out:
 	if (res == -ENOKEY)
@@ -583,9 +583,30 @@ int fscrypt_get_encryption_info(struct inode *inode)
 }
 EXPORT_SYMBOL(fscrypt_get_encryption_info);
 
+/**
+ * fscrypt_put_encryption_info - free most of an inode's fscrypt data
+ *
+ * Free the inode's fscrypt_info.  Filesystems must call this when the inode is
+ * being evicted.  An RCU grace period need not have elapsed yet.
+ */
 void fscrypt_put_encryption_info(struct inode *inode)
 {
 	put_crypt_info(inode->i_crypt_info);
 	inode->i_crypt_info = NULL;
 }
 EXPORT_SYMBOL(fscrypt_put_encryption_info);
+
+/**
+ * fscrypt_free_inode - free an inode's fscrypt data requiring RCU delay
+ *
+ * Free the inode's cached decrypted symlink target, if any.  Filesystems must
+ * call this after an RCU grace period, just before they free the inode.
+ */
+void fscrypt_free_inode(struct inode *inode)
+{
+	if (IS_ENCRYPTED(inode) && S_ISLNK(inode->i_mode)) {
+		kfree(inode->i_link);
+		inode->i_link = NULL;
+	}
+}
+EXPORT_SYMBOL(fscrypt_free_inode);

fs/crypto/policy.c

@@ -194,8 +194,8 @@ int fscrypt_has_permitted_context(struct inode *parent, struct inode *child)
 	res = fscrypt_get_encryption_info(child);
 	if (res)
 		return 0;
-	parent_ci = parent->i_crypt_info;
-	child_ci = child->i_crypt_info;
+	parent_ci = READ_ONCE(parent->i_crypt_info);
+	child_ci = READ_ONCE(child->i_crypt_info);
 
 	if (parent_ci && child_ci) {
 		return memcmp(parent_ci->ci_master_key_descriptor,
@@ -246,7 +246,7 @@ int fscrypt_inherit_context(struct inode *parent, struct inode *child,
 	if (res < 0)
 		return res;
 
-	ci = parent->i_crypt_info;
+	ci = READ_ONCE(parent->i_crypt_info);
 	if (ci == NULL)
 		return -ENOKEY;
 

fs/dcache.c

@@ -18,6 +18,7 @@
 #include <linux/string.h>
 #include <linux/mm.h>
 #include <linux/fs.h>
+#include <linux/fscrypt.h>
 #include <linux/fsnotify.h>
 #include <linux/slab.h>
 #include <linux/init.h>
@@ -2797,6 +2798,7 @@ static void __d_move(struct dentry *dentry, struct dentry *target,
 	list_move(&dentry->d_child, &dentry->d_parent->d_subdirs);
 	__d_rehash(dentry);
 	fsnotify_update_flags(dentry);
+	fscrypt_handle_d_move(dentry);
 
 	write_seqcount_end(&target->d_seq);
 	write_seqcount_end(&dentry->d_seq);

fs/ext4/ext4.h

@@ -2303,23 +2303,47 @@ extern unsigned ext4_free_clusters_after_init(struct super_block *sb,
 ext4_fsblk_t ext4_inode_to_goal_block(struct inode *);
 
 #ifdef CONFIG_FS_ENCRYPTION
+static inline void ext4_fname_from_fscrypt_name(struct ext4_filename *dst,
+						const struct fscrypt_name *src)
+{
+	memset(dst, 0, sizeof(*dst));
+
+	dst->usr_fname = src->usr_fname;
+	dst->disk_name = src->disk_name;
+	dst->hinfo.hash = src->hash;
+	dst->hinfo.minor_hash = src->minor_hash;
+	dst->crypto_buf = src->crypto_buf;
+}
+
 static inline int ext4_fname_setup_filename(struct inode *dir,
 					    const struct qstr *iname,
-			int lookup, struct ext4_filename *fname)
+					    int lookup,
+					    struct ext4_filename *fname)
 {
 	struct fscrypt_name name;
 	int err;
 
-	memset(fname, 0, sizeof(struct ext4_filename));
-
 	err = fscrypt_setup_filename(dir, iname, lookup, &name);
+	if (err)
+		return err;
+
+	ext4_fname_from_fscrypt_name(fname, &name);
+	return 0;
+}
+
+static inline int ext4_fname_prepare_lookup(struct inode *dir,
+					    struct dentry *dentry,
+					    struct ext4_filename *fname)
+{
+	struct fscrypt_name name;
+	int err;
 
-	fname->usr_fname = name.usr_fname;
-	fname->disk_name = name.disk_name;
-	fname->hinfo.hash = name.hash;
-	fname->hinfo.minor_hash = name.minor_hash;
-	fname->crypto_buf = name.crypto_buf;
+	err = fscrypt_prepare_lookup(dir, dentry, &name);
+	if (err)
 		return err;
+
+	ext4_fname_from_fscrypt_name(fname, &name);
+	return 0;
 }
 
 static inline void ext4_fname_free_filename(struct ext4_filename *fname)
@@ -2333,19 +2357,27 @@ static inline void ext4_fname_free_filename(struct ext4_filename *fname)
 	fname->usr_fname = NULL;
 	fname->disk_name.name = NULL;
 }
-#else
+#else /* !CONFIG_FS_ENCRYPTION */
 static inline int ext4_fname_setup_filename(struct inode *dir,
 					    const struct qstr *iname,
-		int lookup, struct ext4_filename *fname)
+					    int lookup,
+					    struct ext4_filename *fname)
 {
 	fname->usr_fname = iname;
 	fname->disk_name.name = (unsigned char *) iname->name;
 	fname->disk_name.len = iname->len;
 	return 0;
 }
-static inline void ext4_fname_free_filename(struct ext4_filename *fname) { }
 
-#endif
+static inline int ext4_fname_prepare_lookup(struct inode *dir,
+					    struct dentry *dentry,
+					    struct ext4_filename *fname)
+{
+	return ext4_fname_setup_filename(dir, &dentry->d_name, 1, fname);
+}
+
+static inline void ext4_fname_free_filename(struct ext4_filename *fname) { }
+#endif /* !CONFIG_FS_ENCRYPTION */
 
 /* dir.c */
 extern int __ext4_check_dir_entry(const char *, unsigned int, struct inode *,

fs/ext4/namei.c

@@ -1371,7 +1371,7 @@ static int is_dx_internal_node(struct inode *dir, ext4_lblk_t block,
 }
 
 /*
- *	ext4_find_entry()
+ *	__ext4_find_entry()
  *
  * finds an entry in the specified directory with the wanted name. It
  * returns the cache buffer in which the entry was found, and the entry
@@ -1381,8 +1381,8 @@ static int is_dx_internal_node(struct inode *dir, ext4_lblk_t block,
  * The returned buffer_head has ->b_count elevated.  The caller is expected
  * to brelse() it when appropriate.
  */
-static struct buffer_head * ext4_find_entry (struct inode *dir,
-					const struct qstr *d_name,
+static struct buffer_head *__ext4_find_entry(struct inode *dir,
+					     struct ext4_filename *fname,
 					     struct ext4_dir_entry_2 **res_dir,
 					     int *inlined)
 {
@@ -1390,30 +1390,23 @@ static struct buffer_head * ext4_find_entry (struct inode *dir,
 	struct buffer_head *bh_use[NAMEI_RA_SIZE];
 	struct buffer_head *bh, *ret = NULL;
 	ext4_lblk_t start, block;
-	const u8 *name = d_name->name;
+	const u8 *name = fname->usr_fname->name;
 	size_t ra_max = 0;	/* Number of bh's in the readahead
 				   buffer, bh_use[] */
 	size_t ra_ptr = 0;	/* Current index into readahead
 				   buffer */
 	ext4_lblk_t  nblocks;
 	int i, namelen, retval;
-	struct ext4_filename fname;
 
 	*res_dir = NULL;
 	sb = dir->i_sb;
-	namelen = d_name->len;
+	namelen = fname->usr_fname->len;
 	if (namelen > EXT4_NAME_LEN)
 		return NULL;
 
-	retval = ext4_fname_setup_filename(dir, d_name, 1, &fname);
-	if (retval == -ENOENT)
-		return NULL;
-	if (retval)
-		return ERR_PTR(retval);
-
 	if (ext4_has_inline_data(dir)) {
 		int has_inline_data = 1;
-		ret = ext4_find_inline_entry(dir, &fname, res_dir,
+		ret = ext4_find_inline_entry(dir, fname, res_dir,
 					     &has_inline_data);
 		if (has_inline_data) {
 			if (inlined)
@@ -1433,7 +1426,7 @@ static struct buffer_head * ext4_find_entry (struct inode *dir,
 		goto restart;
 	}
 	if (is_dx(dir)) {
-		ret = ext4_dx_find_entry(dir, &fname, res_dir);
+		ret = ext4_dx_find_entry(dir, fname, res_dir);
 		/*
 		 * On success, or if the error was file not found,
 		 * return.  Otherwise, fall back to doing a search the
@@ -1497,7 +1490,7 @@ static struct buffer_head * ext4_find_entry (struct inode *dir,
 			goto cleanup_and_exit;
 		}
 		set_buffer_verified(bh);
-		i = search_dirblock(bh, dir, &fname,
+		i = search_dirblock(bh, dir, fname,
 			    block << EXT4_BLOCK_SIZE_BITS(sb), res_dir);
 		if (i == 1) {
 			EXT4_I(dir)->i_dir_start_lookup = block;
@@ -1528,10 +1521,50 @@ static struct buffer_head * ext4_find_entry (struct inode *dir,
 	/* Clean up the read-ahead blocks */
 	for (; ra_ptr < ra_max; ra_ptr++)
 		brelse(bh_use[ra_ptr]);
-	ext4_fname_free_filename(&fname);
 	return ret;
 }
 
+static struct buffer_head *ext4_find_entry(struct inode *dir,
+					   const struct qstr *d_name,
+					   struct ext4_dir_entry_2 **res_dir,
+					   int *inlined)
+{
+	int err;
+	struct ext4_filename fname;
+	struct buffer_head *bh;
+
+	err = ext4_fname_setup_filename(dir, d_name, 1, &fname);
+	if (err == -ENOENT)
+		return NULL;
+	if (err)
+		return ERR_PTR(err);
+
+	bh = __ext4_find_entry(dir, &fname, res_dir, inlined);
+
+	ext4_fname_free_filename(&fname);
+	return bh;
+}
+
+static struct buffer_head *ext4_lookup_entry(struct inode *dir,
+					     struct dentry *dentry,
+					     struct ext4_dir_entry_2 **res_dir)
+{
+	int err;
+	struct ext4_filename fname;
+	struct buffer_head *bh;
+
+	err = ext4_fname_prepare_lookup(dir, dentry, &fname);
+	if (err == -ENOENT)
+		return NULL;
+	if (err)
+		return ERR_PTR(err);
+
+	bh = __ext4_find_entry(dir, &fname, res_dir, NULL);
+
+	ext4_fname_free_filename(&fname);
+	return bh;
+}
+
 static struct buffer_head * ext4_dx_find_entry(struct inode *dir,
 			struct ext4_filename *fname,
 			struct ext4_dir_entry_2 **res_dir)
@@ -1590,16 +1623,11 @@ static struct dentry *ext4_lookup(struct inode *dir, struct dentry *dentry, unsi
 	struct inode *inode;
 	struct ext4_dir_entry_2 *de;
 	struct buffer_head *bh;
-	int err;
-
-	err = fscrypt_prepare_lookup(dir, dentry, flags);
-	if (err)
-		return ERR_PTR(err);
 
 	if (dentry->d_name.len > EXT4_NAME_LEN)
 		return ERR_PTR(-ENAMETOOLONG);
 
-	bh = ext4_find_entry(dir, &dentry->d_name, &de, NULL);
+	bh = ext4_lookup_entry(dir, dentry, &de);
 	if (IS_ERR(bh))
 		return ERR_CAST(bh);
 	inode = NULL;

fs/ext4/readpage.c

@@ -244,7 +244,7 @@ int ext4_mpage_readpages(struct address_space *mapping,
 			struct fscrypt_ctx *ctx = NULL;
 
 			if (IS_ENCRYPTED(inode) && S_ISREG(inode->i_mode)) {
-				ctx = fscrypt_get_ctx(inode, GFP_NOFS);
+				ctx = fscrypt_get_ctx(GFP_NOFS);
 				if (IS_ERR(ctx))
 					goto set_error_page;
 			}

fs/ext4/super.c

@@ -1113,6 +1113,7 @@ static int ext4_drop_inode(struct inode *inode)
 
 static void ext4_free_in_core_inode(struct inode *inode)
 {
+	fscrypt_free_inode(inode);
 	kmem_cache_free(ext4_inode_cachep, EXT4_I(inode));
 }
 

fs/f2fs/namei.c

@@ -436,19 +436,23 @@ static struct dentry *f2fs_lookup(struct inode *dir, struct dentry *dentry,
 	nid_t ino = -1;
 	int err = 0;
 	unsigned int root_ino = F2FS_ROOT_INO(F2FS_I_SB(dir));
+	struct fscrypt_name fname;
 
 	trace_f2fs_lookup_start(dir, dentry, flags);
 
-	err = fscrypt_prepare_lookup(dir, dentry, flags);
-	if (err)
-		goto out;
-
 	if (dentry->d_name.len > F2FS_NAME_LEN) {
 		err = -ENAMETOOLONG;
 		goto out;
 	}
 
-	de = f2fs_find_entry(dir, &dentry->d_name, &page);
+	err = fscrypt_prepare_lookup(dir, dentry, &fname);
+	if (err == -ENOENT)
+		goto out_splice;
+	if (err)
+		goto out;
+	de = __f2fs_find_entry(dir, &fname, &page);
+	fscrypt_free_filename(&fname);
+
 	if (!de) {
 		if (IS_ERR(page)) {
 			err = PTR_ERR(page);
@@ -488,8 +492,7 @@ static struct dentry *f2fs_lookup(struct inode *dir, struct dentry *dentry,
 	}
 out_splice:
 	new = d_splice_alias(inode, dentry);
-	if (IS_ERR(new))
-		err = PTR_ERR(new);
+	err = PTR_ERR_OR_ZERO(new);
 	trace_f2fs_lookup_end(dir, dentry, ino, err);
 	return new;
 out_iput:

fs/f2fs/super.c

@@ -1002,6 +1002,7 @@ static void f2fs_dirty_inode(struct inode *inode, int flags)
 
 static void f2fs_free_inode(struct inode *inode)
 {
+	fscrypt_free_inode(inode);
 	kmem_cache_free(f2fs_inode_cachep, F2FS_I(inode));
 }
 

fs/namei.c

@@ -1066,7 +1066,7 @@ const char *get_link(struct nameidata *nd)
 		return ERR_PTR(error);
 
 	nd->last_type = LAST_BIND;
-	res = inode->i_link;
+	res = READ_ONCE(inode->i_link);
 	if (!res) {
 		const char * (*get)(struct dentry *, struct inode *,
 				struct delayed_call *);
@@ -4729,7 +4729,7 @@ int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen)
 		spin_unlock(&inode->i_lock);
 	}
 
-	link = inode->i_link;
+	link = READ_ONCE(inode->i_link);
 	if (!link) {
 		link = inode->i_op->get_link(dentry, inode, &done);
 		if (IS_ERR(link))

fs/ubifs/dir.c

@@ -220,11 +220,9 @@ static struct dentry *ubifs_lookup(struct inode *dir, struct dentry *dentry,
 
 	dbg_gen("'%pd' in dir ino %lu", dentry, dir->i_ino);
 
-	err = fscrypt_prepare_lookup(dir, dentry, flags);
-	if (err)
-		return ERR_PTR(err);
-
-	err = fscrypt_setup_filename(dir, &dentry->d_name, 1, &nm);
+	err = fscrypt_prepare_lookup(dir, dentry, &nm);
+	if (err == -ENOENT)
+		return d_splice_alias(NULL, dentry);
 	if (err)
 		return ERR_PTR(err);
 

fs/ubifs/super.c

@@ -275,7 +275,10 @@ static struct inode *ubifs_alloc_inode(struct super_block *sb)
 static void ubifs_free_inode(struct inode *inode)
 {
 	struct ubifs_inode *ui = ubifs_inode(inode);
+
 	kfree(ui->data);
+	fscrypt_free_inode(inode);
+
 	kmem_cache_free(ubifs_inode_slab, ui);
 }
 

include/linux/dcache.h

@@ -211,7 +211,7 @@ struct dentry_operations {
 
 #define DCACHE_MAY_FREE			0x00800000
 #define DCACHE_FALLTHRU			0x01000000 /* Fall through to lower layer */
-#define DCACHE_ENCRYPTED_WITH_KEY	0x02000000 /* dir is encrypted with a valid key */
+#define DCACHE_ENCRYPTED_NAME		0x02000000 /* Encrypted name (dir key was unavailable) */
 #define DCACHE_OP_REAL			0x04000000
 
 #define DCACHE_PAR_LOOKUP		0x10000000 /* being looked up (with parent locked shared) */

include/linux/fscrypt.h

@@ -33,6 +33,7 @@ struct fscrypt_name {
 	u32 hash;
 	u32 minor_hash;
 	struct fscrypt_str crypto_buf;
+	bool is_ciphertext_name;
 };
 
 #define FSTR_INIT(n, l)		{ .name = n, .len = l }
@@ -79,7 +80,8 @@ struct fscrypt_ctx {
 
 static inline bool fscrypt_has_encryption_key(const struct inode *inode)
 {
-	return (inode->i_crypt_info != NULL);
+	/* pairs with cmpxchg_release() in fscrypt_get_encryption_info() */
+	return READ_ONCE(inode->i_crypt_info) != NULL;
 }
 
 static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
@@ -88,9 +90,21 @@ static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
 		inode->i_sb->s_cop->dummy_context(inode);
 }
 
+/*
+ * When d_splice_alias() moves a directory's encrypted alias to its decrypted
+ * alias as a result of the encryption key being added, DCACHE_ENCRYPTED_NAME
+ * must be cleared.  Note that we don't have to support arbitrary moves of this
+ * flag because fscrypt doesn't allow encrypted aliases to be the source or
+ * target of a rename().
+ */
+static inline void fscrypt_handle_d_move(struct dentry *dentry)
+{
+	dentry->d_flags &= ~DCACHE_ENCRYPTED_NAME;
+}
+
 /* crypto.c */
 extern void fscrypt_enqueue_decrypt_work(struct work_struct *);
-extern struct fscrypt_ctx *fscrypt_get_ctx(const struct inode *, gfp_t);
+extern struct fscrypt_ctx *fscrypt_get_ctx(gfp_t);
 extern void fscrypt_release_ctx(struct fscrypt_ctx *);
 extern struct page *fscrypt_encrypt_page(const struct inode *, struct page *,
 						unsigned int, unsigned int,
@@ -114,6 +128,7 @@ extern int fscrypt_inherit_context(struct inode *, struct inode *,
 /* keyinfo.c */
 extern int fscrypt_get_encryption_info(struct inode *);
 extern void fscrypt_put_encryption_info(struct inode *);
+extern void fscrypt_free_inode(struct inode *);
 
 /* fname.c */
 extern int fscrypt_setup_filename(struct inode *, const struct qstr *,
@@ -214,13 +229,15 @@ extern int fscrypt_zeroout_range(const struct inode *, pgoff_t, sector_t,
 
 /* hooks.c */
 extern int fscrypt_file_open(struct inode *inode, struct file *filp);
-extern int __fscrypt_prepare_link(struct inode *inode, struct inode *dir);
+extern int __fscrypt_prepare_link(struct inode *inode, struct inode *dir,
+				  struct dentry *dentry);
 extern int __fscrypt_prepare_rename(struct inode *old_dir,
 				    struct dentry *old_dentry,
 				    struct inode *new_dir,
 				    struct dentry *new_dentry,
 				    unsigned int flags);
-extern int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry);
+extern int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry,
+				    struct fscrypt_name *fname);
 extern int __fscrypt_prepare_symlink(struct inode *dir, unsigned int len,
 				     unsigned int max_len,
 				     struct fscrypt_str *disk_link);
@@ -242,13 +259,16 @@ static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
 	return false;
 }
 
+static inline void fscrypt_handle_d_move(struct dentry *dentry)
+{
+}
+
 /* crypto.c */
 static inline void fscrypt_enqueue_decrypt_work(struct work_struct *work)
 {
 }
 
-static inline struct fscrypt_ctx *fscrypt_get_ctx(const struct inode *inode,
-						  gfp_t gfp_flags)
+static inline struct fscrypt_ctx *fscrypt_get_ctx(gfp_t gfp_flags)
 {
 	return ERR_PTR(-EOPNOTSUPP);
 }
@@ -322,6 +342,10 @@ static inline void fscrypt_put_encryption_info(struct inode *inode)
 	return;
 }
 
+static inline void fscrypt_free_inode(struct inode *inode)
+{
+}
+
  /* fname.c */
 static inline int fscrypt_setup_filename(struct inode *dir,
 					 const struct qstr *iname,
@@ -330,7 +354,7 @@ static inline int fscrypt_setup_filename(struct inode *dir,
 	if (IS_ENCRYPTED(dir))
 		return -EOPNOTSUPP;
 
-	memset(fname, 0, sizeof(struct fscrypt_name));
+	memset(fname, 0, sizeof(*fname));
 	fname->usr_fname = iname;
 	fname->disk_name.name = (unsigned char *)iname->name;
 	fname->disk_name.len = iname->len;
@@ -401,8 +425,8 @@ static inline int fscrypt_file_open(struct inode *inode, struct file *filp)
 	return 0;
 }
 
-static inline int __fscrypt_prepare_link(struct inode *inode,
-					 struct inode *dir)
+static inline int __fscrypt_prepare_link(struct inode *inode, struct inode *dir,
+					 struct dentry *dentry)
 {
 	return -EOPNOTSUPP;
 }
@@ -417,7 +441,8 @@ static inline int __fscrypt_prepare_rename(struct inode *old_dir,
 }
 
 static inline int __fscrypt_prepare_lookup(struct inode *dir,
-					   struct dentry *dentry)
+					   struct dentry *dentry,
+					   struct fscrypt_name *fname)
 {
 	return -EOPNOTSUPP;
 }
@@ -497,7 +522,7 @@ static inline int fscrypt_prepare_link(struct dentry *old_dentry,
 				       struct dentry *dentry)
 {
 	if (IS_ENCRYPTED(dir))
-		return __fscrypt_prepare_link(d_inode(old_dentry), dir);
+		return __fscrypt_prepare_link(d_inode(old_dentry), dir, dentry);
 	return 0;
 }
 
@@ -538,27 +563,32 @@ static inline int fscrypt_prepare_rename(struct inode *old_dir,
  * fscrypt_prepare_lookup - prepare to lookup a name in a possibly-encrypted directory
  * @dir: directory being searched
  * @dentry: filename being looked up
- * @flags: lookup flags
+ * @fname: (output) the name to use to search the on-disk directory
  *
- * Prepare for ->lookup() in a directory which may be encrypted.  Lookups can be
- * done with or without the directory's encryption key; without the key,
+ * Prepare for ->lookup() in a directory which may be encrypted by determining
+ * the name that will actually be used to search the directory on-disk.  Lookups
+ * can be done with or without the directory's encryption key; without the key,
  * filenames are presented in encrypted form.  Therefore, we'll try to set up
  * the directory's encryption key, but even without it the lookup can continue.
  *
- * To allow invalidating stale dentries if the directory's encryption key is
- * added later, we also install a custom ->d_revalidate() method and use the
- * DCACHE_ENCRYPTED_WITH_KEY flag to indicate whether a given dentry is a
- * plaintext name (flag set) or a ciphertext name (flag cleared).
+ * This also installs a custom ->d_revalidate() method which will invalidate the
+ * dentry if it was created without the key and the key is later added.
  *
- * Return: 0 on success, -errno if a problem occurred while setting up the
- * encryption key
+ * Return: 0 on success; -ENOENT if key is unavailable but the filename isn't a
+ * correctly formed encoded ciphertext name, so a negative dentry should be
+ * created; or another -errno code.
  */
 static inline int fscrypt_prepare_lookup(struct inode *dir,
 					 struct dentry *dentry,
-					 unsigned int flags)
+					 struct fscrypt_name *fname)
 {
 	if (IS_ENCRYPTED(dir))
-		return __fscrypt_prepare_lookup(dir, dentry);
+		return __fscrypt_prepare_lookup(dir, dentry, fname);
+
+	memset(fname, 0, sizeof(*fname));
+	fname->usr_fname = &dentry->d_name;
+	fname->disk_name.name = (unsigned char *)dentry->d_name.name;
+	fname->disk_name.len = dentry->d_name.len;
 	return 0;
 }