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

Pull fscrypt updates from Ted Ts'o:
 "Refactor support for encrypted symlinks to move common code to fscrypt"

Ted also points out about the merge:
 "This makes the f2fs symlink code use the fscrypt_encrypt_symlink()
  from the fscrypt tree. This will end up dropping the kzalloc() ->
  f2fs_kzalloc() change, which means the fscrypt-specific allocation
  won't get tested by f2fs's kmalloc error injection system; which is
  fine"

* tag 'fscrypt_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/fscrypt: (26 commits)
  fscrypt: fix build with pre-4.6 gcc versions
  fscrypt: remove 'ci' parameter from fscrypt_put_encryption_info()
  fscrypt: document symlink length restriction
  fscrypt: fix up fscrypt_fname_encrypted_size() for internal use
  fscrypt: define fscrypt_fname_alloc_buffer() to be for presented names
  fscrypt: calculate NUL-padding length in one place only
  fscrypt: move fscrypt_symlink_data to fscrypt_private.h
  fscrypt: remove fscrypt_fname_usr_to_disk()
  ubifs: switch to fscrypt_get_symlink()
  ubifs: switch to fscrypt ->symlink() helper functions
  ubifs: free the encrypted symlink target
  f2fs: switch to fscrypt_get_symlink()
  f2fs: switch to fscrypt ->symlink() helper functions
  ext4: switch to fscrypt_get_symlink()
  ext4: switch to fscrypt ->symlink() helper functions
  fscrypt: new helper function - fscrypt_get_symlink()
  fscrypt: new helper functions for ->symlink()
  fscrypt: trim down fscrypt.h includes
  fscrypt: move fscrypt_is_dot_dotdot() to fs/crypto/fname.c
  fscrypt: move fscrypt_valid_enc_modes() to fscrypt_private.h
  ...

3 files changed, 171 insertions, 130 deletions

diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
index 08b4b40c5aa8..952ab97af325 100644
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -14,42 +14,13 @@
 #ifndef _LINUX_FSCRYPT_H
 #define _LINUX_FSCRYPT_H
 
-#include <linux/key.h>
 #include <linux/fs.h>
-#include <linux/mm.h>
-#include <linux/bio.h>
-#include <linux/dcache.h>
-#include <crypto/skcipher.h>
-#include <uapi/linux/fs.h>
 
 #define FS_CRYPTO_BLOCK_SIZE		16
 
+struct fscrypt_ctx;
 struct fscrypt_info;
 
-struct fscrypt_ctx {
-	union {
-		struct {
-			struct page *bounce_page;	/* Ciphertext page */
-			struct page *control_page;	/* Original page  */
-		} w;
-		struct {
-			struct bio *bio;
-			struct work_struct work;
-		} r;
-		struct list_head free_list;	/* Free list */
-	};
-	u8 flags;				/* Flags */
-};
-
-/**
- * For encrypted symlinks, the ciphertext length is stored at the beginning
- * of the string in little-endian format.
- */
-struct fscrypt_symlink_data {
-	__le16 len;
-	char encrypted_path[1];
-} __packed;
-
 struct fscrypt_str {
 	unsigned char *name;
 	u32 len;
@@ -68,89 +39,14 @@ struct fscrypt_name {
 #define fname_name(p)		((p)->disk_name.name)
 #define fname_len(p)		((p)->disk_name.len)
 
-/*
- * fscrypt superblock flags
- */
-#define FS_CFLG_OWN_PAGES (1U << 1)
-
-/*
- * crypto opertions for filesystems
- */
-struct fscrypt_operations {
-	unsigned int flags;
-	const char *key_prefix;
-	int (*get_context)(struct inode *, void *, size_t);
-	int (*set_context)(struct inode *, const void *, size_t, void *);
-	bool (*dummy_context)(struct inode *);
-	bool (*empty_dir)(struct inode *);
-	unsigned (*max_namelen)(struct inode *);
-};
-
 /* Maximum value for the third parameter of fscrypt_operations.set_context(). */
 #define FSCRYPT_SET_CONTEXT_MAX_SIZE	28
 
-static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
-{
-	if (inode->i_sb->s_cop->dummy_context &&
-				inode->i_sb->s_cop->dummy_context(inode))
-		return true;
-	return false;
-}
-
-static inline bool fscrypt_valid_enc_modes(u32 contents_mode,
-					u32 filenames_mode)
-{
-	if (contents_mode == FS_ENCRYPTION_MODE_AES_128_CBC &&
-	    filenames_mode == FS_ENCRYPTION_MODE_AES_128_CTS)
-		return true;
-
-	if (contents_mode == FS_ENCRYPTION_MODE_AES_256_XTS &&
-	    filenames_mode == FS_ENCRYPTION_MODE_AES_256_CTS)
-		return true;
-
-	return false;
-}
-
-static inline bool fscrypt_is_dot_dotdot(const struct qstr *str)
-{
-	if (str->len == 1 && str->name[0] == '.')
-		return true;
-
-	if (str->len == 2 && str->name[0] == '.' && str->name[1] == '.')
-		return true;
-
-	return false;
-}
-
 #if __FS_HAS_ENCRYPTION
-
-static inline struct page *fscrypt_control_page(struct page *page)
-{
-	return ((struct fscrypt_ctx *)page_private(page))->w.control_page;
-}
-
-static inline bool fscrypt_has_encryption_key(const struct inode *inode)
-{
-	return (inode->i_crypt_info != NULL);
-}
-
 #include <linux/fscrypt_supp.h>
-
-#else /* !__FS_HAS_ENCRYPTION */
-
-static inline struct page *fscrypt_control_page(struct page *page)
-{
-	WARN_ON_ONCE(1);
-	return ERR_PTR(-EINVAL);
-}
-
-static inline bool fscrypt_has_encryption_key(const struct inode *inode)
-{
-	return 0;
-}
-
+#else
 #include <linux/fscrypt_notsupp.h>
-#endif /* __FS_HAS_ENCRYPTION */
+#endif
 
 /**
  * fscrypt_require_key - require an inode's encryption key
@@ -291,4 +187,68 @@ static inline int fscrypt_prepare_setattr(struct dentry *dentry,
 	return 0;
 }
 
+/**
+ * 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.
+ */
+static inline int fscrypt_prepare_symlink(struct inode *dir,
+					  const char *target,
+					  unsigned int len,
+					  unsigned int max_len,
+					  struct fscrypt_str *disk_link)
+{
+	if (IS_ENCRYPTED(dir) || fscrypt_dummy_context_enabled(dir))
+		return __fscrypt_prepare_symlink(dir, len, max_len, disk_link);
+
+	disk_link->name = (unsigned char *)target;
+	disk_link->len = len + 1;
+	if (disk_link->len > max_len)
+		return -ENAMETOOLONG;
+	return 0;
+}
+
+/**
+ * fscrypt_encrypt_symlink - encrypt the symlink target if needed
+ * @inode: symlink inode
+ * @target: plaintext symlink target
+ * @len: length of @target excluding null terminator
+ * @disk_link: (in/out) the on-disk symlink target being prepared
+ *
+ * If the symlink target needs to be encrypted, then this function encrypts it
+ * into @disk_link->name.  fscrypt_prepare_symlink() must have been called
+ * previously to compute @disk_link->len.  If the filesystem did not allocate a
+ * buffer for @disk_link->name after calling fscrypt_prepare_link(), then one
+ * will be kmalloc()'ed and the filesystem will be responsible for freeing it.
+ *
+ * Return: 0 on success, -errno on failure
+ */
+static inline int fscrypt_encrypt_symlink(struct inode *inode,
+					  const char *target,
+					  unsigned int len,
+					  struct fscrypt_str *disk_link)
+{
+	if (IS_ENCRYPTED(inode))
+		return __fscrypt_encrypt_symlink(inode, target, len, disk_link);
+	return 0;
+}
+
 #endif	/* _LINUX_FSCRYPT_H */
diff --git a/include/linux/fscrypt_notsupp.h b/include/linux/fscrypt_notsupp.h
index 63e58808519a..44b50c04bae9 100644
--- a/include/linux/fscrypt_notsupp.h
+++ b/include/linux/fscrypt_notsupp.h
@@ -14,6 +14,16 @@
 #ifndef _LINUX_FSCRYPT_NOTSUPP_H
 #define _LINUX_FSCRYPT_NOTSUPP_H
 
+static inline bool fscrypt_has_encryption_key(const struct inode *inode)
+{
+	return false;
+}
+
+static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
+{
+	return false;
+}
+
 /* crypto.c */
 static inline struct fscrypt_ctx *fscrypt_get_ctx(const struct inode *inode,
 						  gfp_t gfp_flags)
@@ -43,6 +53,11 @@ static inline int fscrypt_decrypt_page(const struct inode *inode,
 	return -EOPNOTSUPP;
 }
 
+static inline struct page *fscrypt_control_page(struct page *page)
+{
+	WARN_ON_ONCE(1);
+	return ERR_PTR(-EINVAL);
+}
 
 static inline void fscrypt_restore_control_page(struct page *page)
 {
@@ -90,8 +105,7 @@ static inline int fscrypt_get_encryption_info(struct inode *inode)
 	return -EOPNOTSUPP;
 }
 
-static inline void fscrypt_put_encryption_info(struct inode *inode,
-					       struct fscrypt_info *ci)
+static inline void fscrypt_put_encryption_info(struct inode *inode)
 {
 	return;
 }
@@ -116,16 +130,8 @@ static inline void fscrypt_free_filename(struct fscrypt_name *fname)
 	return;
 }
 
-static inline u32 fscrypt_fname_encrypted_size(const struct inode *inode,
-					       u32 ilen)
-{
-	/* never happens */
-	WARN_ON(1);
-	return 0;
-}
-
 static inline int fscrypt_fname_alloc_buffer(const struct inode *inode,
-					     u32 ilen,
+					     u32 max_encrypted_len,
 					     struct fscrypt_str *crypto_str)
 {
 	return -EOPNOTSUPP;
@@ -144,13 +150,6 @@ static inline int fscrypt_fname_disk_to_usr(struct inode *inode,
 	return -EOPNOTSUPP;
 }
 
-static inline int fscrypt_fname_usr_to_disk(struct inode *inode,
-					    const struct qstr *iname,
-					    struct fscrypt_str *oname)
-{
-	return -EOPNOTSUPP;
-}
-
 static inline bool fscrypt_match_name(const struct fscrypt_name *fname,
 				      const u8 *de_name, u32 de_name_len)
 {
@@ -208,4 +207,28 @@ static inline int __fscrypt_prepare_lookup(struct inode *dir,
 	return -EOPNOTSUPP;
 }
 
+static inline int __fscrypt_prepare_symlink(struct inode *dir,
+					    unsigned int len,
+					    unsigned int max_len,
+					    struct fscrypt_str *disk_link)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int __fscrypt_encrypt_symlink(struct inode *inode,
+					    const char *target,
+					    unsigned int len,
+					    struct fscrypt_str *disk_link)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline const char *fscrypt_get_symlink(struct inode *inode,
+					      const void *caddr,
+					      unsigned int max_size,
+					      struct delayed_call *done)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+
 #endif	/* _LINUX_FSCRYPT_NOTSUPP_H */
diff --git a/include/linux/fscrypt_supp.h b/include/linux/fscrypt_supp.h
index cf9e9fc02f0a..477a7a6504d2 100644
--- a/include/linux/fscrypt_supp.h
+++ b/include/linux/fscrypt_supp.h
@@ -11,8 +11,54 @@
 #ifndef _LINUX_FSCRYPT_SUPP_H
 #define _LINUX_FSCRYPT_SUPP_H
 
+#include <linux/mm.h>
+#include <linux/slab.h>
+
+/*
+ * fscrypt superblock flags
+ */
+#define FS_CFLG_OWN_PAGES (1U << 1)
+
+/*
+ * crypto operations for filesystems
+ */
+struct fscrypt_operations {
+	unsigned int flags;
+	const char *key_prefix;
+	int (*get_context)(struct inode *, void *, size_t);
+	int (*set_context)(struct inode *, const void *, size_t, void *);
+	bool (*dummy_context)(struct inode *);
+	bool (*empty_dir)(struct inode *);
+	unsigned (*max_namelen)(struct inode *);
+};
+
+struct fscrypt_ctx {
+	union {
+		struct {
+			struct page *bounce_page;	/* Ciphertext page */
+			struct page *control_page;	/* Original page  */
+		} w;
+		struct {
+			struct bio *bio;
+			struct work_struct work;
+		} r;
+		struct list_head free_list;	/* Free list */
+	};
+	u8 flags;				/* Flags */
+};
+
+static inline bool fscrypt_has_encryption_key(const struct inode *inode)
+{
+	return (inode->i_crypt_info != NULL);
+}
+
+static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
+{
+	return inode->i_sb->s_cop->dummy_context &&
+		inode->i_sb->s_cop->dummy_context(inode);
+}
+
 /* crypto.c */
-extern struct kmem_cache *fscrypt_info_cachep;
 extern struct fscrypt_ctx *fscrypt_get_ctx(const struct inode *, gfp_t);
 extern void fscrypt_release_ctx(struct fscrypt_ctx *);
 extern struct page *fscrypt_encrypt_page(const struct inode *, struct page *,
@@ -20,6 +66,12 @@ extern struct page *fscrypt_encrypt_page(const struct inode *, struct page *,
 						u64, gfp_t);
 extern int fscrypt_decrypt_page(const struct inode *, struct page *, unsigned int,
 				unsigned int, u64);
+
+static inline struct page *fscrypt_control_page(struct page *page)
+{
+	return ((struct fscrypt_ctx *)page_private(page))->w.control_page;
+}
+
 extern void fscrypt_restore_control_page(struct page *);
 
 extern const struct dentry_operations fscrypt_d_ops;
@@ -44,7 +96,7 @@ extern int fscrypt_inherit_context(struct inode *, struct inode *,
 					void *, bool);
 /* keyinfo.c */
 extern int fscrypt_get_encryption_info(struct inode *);
-extern void fscrypt_put_encryption_info(struct inode *, struct fscrypt_info *);
+extern void fscrypt_put_encryption_info(struct inode *);
 
 /* fname.c */
 extern int fscrypt_setup_filename(struct inode *, const struct qstr *,
@@ -55,14 +107,11 @@ static inline void fscrypt_free_filename(struct fscrypt_name *fname)
 	kfree(fname->crypto_buf.name);
 }
 
-extern u32 fscrypt_fname_encrypted_size(const struct inode *, u32);
 extern int fscrypt_fname_alloc_buffer(const struct inode *, u32,
 				struct fscrypt_str *);
 extern void fscrypt_fname_free_buffer(struct fscrypt_str *);
 extern int fscrypt_fname_disk_to_usr(struct inode *, u32, u32,
 			const struct fscrypt_str *, struct fscrypt_str *);
-extern int fscrypt_fname_usr_to_disk(struct inode *, const struct qstr *,
-			struct fscrypt_str *);
 
 #define FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE	32
 
@@ -153,5 +202,14 @@ extern int __fscrypt_prepare_rename(struct inode *old_dir,
 				    struct dentry *new_dentry,
 				    unsigned int flags);
 extern int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry);
+extern int __fscrypt_prepare_symlink(struct inode *dir, unsigned int len,
+				     unsigned int max_len,
+				     struct fscrypt_str *disk_link);
+extern int __fscrypt_encrypt_symlink(struct inode *inode, const char *target,
+				     unsigned int len,
+				     struct fscrypt_str *disk_link);
+extern const char *fscrypt_get_symlink(struct inode *inode, const void *caddr,
+				       unsigned int max_size,
+				       struct delayed_call *done);
 
 #endif	/* _LINUX_FSCRYPT_SUPP_H */