1 files changed, 67 insertions, 107 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 */