1 files changed, 54 insertions, 26 deletions

diff --git a/fs/crypto/hooks.c b/fs/crypto/hooks.c
index 09fb8aa0f2e9..20b0df47fe6a 100644
--- a/fs/crypto/hooks.c
+++ b/fs/crypto/hooks.c
@@ -60,8 +60,8 @@ 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)
+	/* ... in case we looked up no-key name before key was added */
+	if (dentry->d_flags & DCACHE_NOKEY_NAME)
 		return -ENOKEY;
 
 	if (!fscrypt_has_permitted_context(dir, inode))
@@ -85,9 +85,8 @@ 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)
+	/* ... in case we looked up no-key name(s) before key was added */
+	if ((old_dentry->d_flags | new_dentry->d_flags) & DCACHE_NOKEY_NAME)
 		return -ENOKEY;
 
 	if (old_dir != new_dir) {
@@ -114,9 +113,9 @@ int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry,
 	if (err && err != -ENOENT)
 		return err;
 
-	if (fname->is_ciphertext_name) {
+	if (fname->is_nokey_name) {
 		spin_lock(&dentry->d_lock);
-		dentry->d_flags |= DCACHE_ENCRYPTED_NAME;
+		dentry->d_flags |= DCACHE_NOKEY_NAME;
 		spin_unlock(&dentry->d_lock);
 		d_set_d_op(dentry, &fscrypt_d_ops);
 	}
@@ -166,26 +165,51 @@ int fscrypt_prepare_setflags(struct inode *inode,
 	return 0;
 }
 
-int __fscrypt_prepare_symlink(struct inode *dir, unsigned int len,
-			      unsigned int max_len,
-			      struct fscrypt_str *disk_link)
+/**
+ * fscrypt_prepare_symlink() - prepare to create a possibly-encrypted symlink
+ * @dir: directory in which the symlink is being created
+ * @target: plaintext symlink target
+ * @len: length of @target excluding null terminator
+ * @max_len: space the filesystem has available to store the symlink target
+ * @disk_link: (out) the on-disk symlink target being prepared
+ *
+ * This function computes the size the symlink target will require on-disk,
+ * stores it in @disk_link->len, and validates it against @max_len.  An
+ * encrypted symlink may be longer than the original.
+ *
+ * Additionally, @disk_link->name is set to @target if the symlink will be
+ * unencrypted, but left NULL if the symlink will be encrypted.  For encrypted
+ * symlinks, the filesystem must call fscrypt_encrypt_symlink() to create the
+ * on-disk target later.  (The reason for the two-step process is that some
+ * filesystems need to know the size of the symlink target before creating the
+ * inode, e.g. to determine whether it will be a "fast" or "slow" symlink.)
+ *
+ * Return: 0 on success, -ENAMETOOLONG if the symlink target is too long,
+ * -ENOKEY if the encryption key is missing, or another -errno code if a problem
+ * occurred while setting up the encryption key.
+ */
+int fscrypt_prepare_symlink(struct inode *dir, const char *target,
+			    unsigned int len, unsigned int max_len,
+			    struct fscrypt_str *disk_link)
 {
-	int err;
+	const union fscrypt_policy *policy;
 
 	/*
 	 * To calculate the size of the encrypted symlink target we need to know
 	 * the amount of NUL padding, which is determined by the flags set in
 	 * the encryption policy which will be inherited from the directory.
-	 * The easiest way to get access to this is to just load the directory's
-	 * fscrypt_info, since we'll need it to create the dir_entry anyway.
-	 *
-	 * Note: in test_dummy_encryption mode, @dir may be unencrypted.
 	 */
-	err = fscrypt_get_encryption_info(dir);
-	if (err)
-		return err;
-	if (!fscrypt_has_encryption_key(dir))
-		return -ENOKEY;
+	policy = fscrypt_policy_to_inherit(dir);
+	if (policy == NULL) {
+		/* Not encrypted */
+		disk_link->name = (unsigned char *)target;
+		disk_link->len = len + 1;
+		if (disk_link->len > max_len)
+			return -ENAMETOOLONG;
+		return 0;
+	}
+	if (IS_ERR(policy))
+		return PTR_ERR(policy);
 
 	/*
 	 * Calculate the size of the encrypted symlink and verify it won't
@@ -198,7 +222,7 @@ int __fscrypt_prepare_symlink(struct inode *dir, unsigned int len,
 	 * counting it (even though it is meaningless for ciphertext) is simpler
 	 * for now since filesystems will assume it is there and subtract it.
 	 */
-	if (!fscrypt_fname_encrypted_size(dir, len,
+	if (!fscrypt_fname_encrypted_size(policy, len,
 					  max_len - sizeof(struct fscrypt_symlink_data),
 					  &disk_link->len))
 		return -ENAMETOOLONG;
@@ -207,7 +231,7 @@ int __fscrypt_prepare_symlink(struct inode *dir, unsigned int len,
 	disk_link->name = NULL;
 	return 0;
 }
-EXPORT_SYMBOL_GPL(__fscrypt_prepare_symlink);
+EXPORT_SYMBOL_GPL(fscrypt_prepare_symlink);
 
 int __fscrypt_encrypt_symlink(struct inode *inode, const char *target,
 			      unsigned int len, struct fscrypt_str *disk_link)
@@ -217,9 +241,13 @@ int __fscrypt_encrypt_symlink(struct inode *inode, const char *target,
 	struct fscrypt_symlink_data *sd;
 	unsigned int ciphertext_len;
 
-	err = fscrypt_require_key(inode);
-	if (err)
-		return err;
+	/*
+	 * fscrypt_prepare_new_inode() should have already set up the new
+	 * symlink inode's encryption key.  We don't wait until now to do it,
+	 * since we may be in a filesystem transaction now.
+	 */
+	if (WARN_ON_ONCE(!fscrypt_has_encryption_key(inode)))
+		return -ENOKEY;
 
 	if (disk_link->name) {
 		/* filesystem-provided buffer */
@@ -319,7 +347,7 @@ const char *fscrypt_get_symlink(struct inode *inode, const void *caddr,
 	if (cstr.len + sizeof(*sd) - 1 > max_size)
 		return ERR_PTR(-EUCLEAN);
 
-	err = fscrypt_fname_alloc_buffer(inode, cstr.len, &pstr);
+	err = fscrypt_fname_alloc_buffer(cstr.len, &pstr);
 	if (err)
 		return ERR_PTR(err);