fscrypt: move fscrypt_prepare_symlink() out-of-line

In preparation for moving the logic for "get the encryption policy
inherited by new files in this directory" to a single place, make
fscrypt_prepare_symlink() a regular function rather than an inline
function that wraps __fscrypt_prepare_symlink().

This way, the new function fscrypt_policy_to_inherit() won't need to be
exported to filesystems.

Acked-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20200917041136.178600-12-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>

diff --git a/fs/crypto/hooks.c b/fs/crypto/hooks.c
index 7748db5..a399c54 100644 (file)
--- a/fs/crypto/hooks.c
+++ b/fs/crypto/hooks.c
@@ -166,12 +166,43 @@ 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;
 
+       if (!IS_ENCRYPTED(dir) && !fscrypt_get_dummy_context(dir->i_sb)) {
+               disk_link->name = (unsigned char *)target;
+               disk_link->len = len + 1;
+               if (disk_link->len > max_len)
+                       return -ENAMETOOLONG;
+               return 0;
+       }
+
        /*
         * 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
@@ -207,7 +238,7 @@ 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)

diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
index 81d6ded..39e7397 100644 (file)
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -225,9 +225,9 @@ int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry,
                             struct fscrypt_name *fname);
 int fscrypt_prepare_setflags(struct inode *inode,
                             unsigned int oldflags, unsigned int flags);
-int __fscrypt_prepare_symlink(struct inode *dir, unsigned int len,
-                             unsigned int max_len,
-                             struct fscrypt_str *disk_link);
+int fscrypt_prepare_symlink(struct inode *dir, const char *target,
+                           unsigned int len, unsigned int max_len,
+                           struct fscrypt_str *disk_link);
 int __fscrypt_encrypt_symlink(struct inode *inode, const char *target,
                              unsigned int len, struct fscrypt_str *disk_link);
 const char *fscrypt_get_symlink(struct inode *inode, const void *caddr,
@@ -520,15 +520,21 @@ static inline int fscrypt_prepare_setflags(struct inode *inode,
        return 0;
 }
 
-static inline int __fscrypt_prepare_symlink(struct inode *dir,
-                                           unsigned int len,
-                                           unsigned int max_len,
-                                           struct fscrypt_str *disk_link)
+static inline int fscrypt_prepare_symlink(struct inode *dir,
+                                         const char *target,
+                                         unsigned int len,
+                                         unsigned int max_len,
+                                         struct fscrypt_str *disk_link)
 {
-       return -EOPNOTSUPP;
+       if (IS_ENCRYPTED(dir))
+               return -EOPNOTSUPP;
+       disk_link->name = (unsigned char *)target;
+       disk_link->len = len + 1;
+       if (disk_link->len > max_len)
+               return -ENAMETOOLONG;
+       return 0;
 }
 
-
 static inline int __fscrypt_encrypt_symlink(struct inode *inode,
                                            const char *target,
                                            unsigned int len,
@@ -794,45 +800,6 @@ static inline int fscrypt_prepare_setattr(struct dentry *dentry,
 }
 
 /**
- * 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_get_dummy_context(dir->i_sb) != NULL)
-               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