eCryptfs: Combine page_offset crypto functions

Combine ecryptfs_encrypt_page_offset() and
ecryptfs_decrypt_page_offset(). These two functions are functionally
identical so they can be safely merged if the caller can indicate
whether an encryption or decryption operation should occur.

Signed-off-by: Tyler Hicks <tyhicks@canonical.com>

1 files changed, 18 insertions, 51 deletions

diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index fb54a0182f2e..609efc01d5c2 100644
--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -40,14 +40,9 @@
 #define DECRYPT         0
 #define ENCRYPT         1
 
-static int
-ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
-                             struct page *dst_page, struct page *src_page,
-                             int offset, int size, unsigned char *iv);
-static int
-ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
+static int crypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
                              struct page *dst_page, struct page *src_page,
-                             int offset, int size, unsigned char *iv);
+                             int offset, int size, unsigned char *iv, int op);
 
 /**
  * ecryptfs_to_hex
@@ -452,9 +447,9 @@ static int ecryptfs_encrypt_extent(struct page *enc_extent_page,
                         (unsigned long long)(extent_base + extent_offset), rc);
                 goto out;
         }
-        rc = ecryptfs_encrypt_page_offset(crypt_stat, enc_extent_page, page,
-                                        extent_offset * crypt_stat->extent_size,
-                                        crypt_stat->extent_size, extent_iv);
+        rc = crypt_page_offset(crypt_stat, enc_extent_page, page,
+                               (extent_offset * crypt_stat->extent_size),
+                               crypt_stat->extent_size, extent_iv, ENCRYPT);
         if (rc < 0) {
                 printk(KERN_ERR "%s: Error attempting to encrypt page with "
                        "page->index = [%ld], extent_offset = [%ld]; "
@@ -555,9 +550,9 @@ static int ecryptfs_decrypt_extent(struct page *page,
                         (unsigned long long)(extent_base + extent_offset), rc);
                 goto out;
         }
-        rc = ecryptfs_decrypt_page_offset(crypt_stat, page, enc_extent_page,
-                                        extent_offset * crypt_stat->extent_size,
-                                        crypt_stat->extent_size, extent_iv);
+        rc = crypt_page_offset(crypt_stat, page, enc_extent_page,
+                               (extent_offset * crypt_stat->extent_size),
+                               crypt_stat->extent_size, extent_iv, DECRYPT);
         if (rc < 0) {
                 printk(KERN_ERR "%s: Error attempting to decrypt to page with "
                        "page->index = [%ld], extent_offset = [%ld]; "
@@ -628,20 +623,20 @@ out:
 }
 
 /**
- * ecryptfs_encrypt_page_offset
+ * crypt_page_offset
  * @crypt_stat: The cryptographic context
- * @dst_page: The page to encrypt into
- * @src_page: The page to encrypt from
+ * @dst_page: The page to write the result into
+ * @src_page: The page to read from
  * @offset: The byte offset into the dst_page and src_page
- * @size: The number of bytes to encrypt
- * @iv: The initialization vector to use for the encryption
+ * @size: The number of bytes of data
+ * @iv: The initialization vector to use for the crypto operation
+ * @op: ENCRYPT or DECRYPT to indicate the desired operation
  *
- * Returns the number of bytes encrypted
+ * Returns the number of bytes encrypted or decrypted
  */
-static int
-ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
+static int crypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
                              struct page *dst_page, struct page *src_page,
-                             int offset, int size, unsigned char *iv)
+                             int offset, int size, unsigned char *iv, int op)
 {
         struct scatterlist src_sg, dst_sg;
 
@@ -650,36 +645,8 @@ ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
 
         sg_set_page(&src_sg, src_page, size, offset);
         sg_set_page(&dst_sg, dst_page, size, offset);
-        return crypt_scatterlist(crypt_stat, &dst_sg, &src_sg,
-                                 size, iv, ENCRYPT);
-}
-
-/**
- * ecryptfs_decrypt_page_offset
- * @crypt_stat: The cryptographic context
- * @dst_page: The page to decrypt into
- * @src_page: The page to decrypt from
- * @offset: The byte offset into the dst_page and src_page
- * @size: The number of bytes to decrypt
- * @iv: The initialization vector to use for the decryption
- *
- * Returns the number of bytes decrypted
- */
-static int
-ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
-                             struct page *dst_page, struct page *src_page,
-                             int offset, int size, unsigned char *iv)
-{
-        struct scatterlist src_sg, dst_sg;
-
-        sg_init_table(&src_sg, 1);
-        sg_set_page(&src_sg, src_page, size, offset);
-
-        sg_init_table(&dst_sg, 1);
-        sg_set_page(&dst_sg, dst_page, size, offset);
 
-        return crypt_scatterlist(crypt_stat, &dst_sg, &src_sg,
-                                 size, iv, DECRYPT);
+        return crypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv, op);
 }
 
 #define ECRYPTFS_MAX_SCATTERLIST_LEN 4