libceph: factor out __ceph_x_decrypt()

Will be used for decrypting the server challenge which is only preceded
by ceph_x_encrypt_header.

Drop struct_v check to allow for extending ceph_x_encrypt_header in the
future.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Sage Weil <sage@redhat.com>

1 files changed, 24 insertions, 9 deletions

diff --git a/net/ceph/auth_x.c b/net/ceph/auth_x.c
index 6caac27fca85..cd1118d106a5 100644
--- a/net/ceph/auth_x.c
+++ b/net/ceph/auth_x.c
@@ -70,25 +70,40 @@ static int ceph_x_encrypt(struct ceph_crypto_key *secret, void *buf,
         return sizeof(u32) + ciphertext_len;
 }
 
+static int __ceph_x_decrypt(struct ceph_crypto_key *secret, void *p,
+                            int ciphertext_len)
+{
+        struct ceph_x_encrypt_header *hdr = p;
+        int plaintext_len;
+        int ret;
+
+        ret = ceph_crypt(secret, false, p, ciphertext_len, ciphertext_len,
+                         &plaintext_len);
+        if (ret)
+                return ret;
+
+        if (le64_to_cpu(hdr->magic) != CEPHX_ENC_MAGIC) {
+                pr_err("%s bad magic\n", __func__);
+                return -EINVAL;
+        }
+
+        return plaintext_len - sizeof(*hdr);
+}
+
 static int ceph_x_decrypt(struct ceph_crypto_key *secret, void **p, void *end)
 {
-        struct ceph_x_encrypt_header *hdr = *p + sizeof(u32);
-        int ciphertext_len, plaintext_len;
+        int ciphertext_len;
         int ret;
 
         ceph_decode_32_safe(p, end, ciphertext_len, e_inval);
         ceph_decode_need(p, end, ciphertext_len, e_inval);
 
-        ret = ceph_crypt(secret, false, *p, end - *p, ciphertext_len,
-                         &plaintext_len);
-        if (ret)
+        ret = __ceph_x_decrypt(secret, *p, ciphertext_len);
+        if (ret < 0)
                 return ret;
 
-        if (hdr->struct_v != 1 || le64_to_cpu(hdr->magic) != CEPHX_ENC_MAGIC)
-                return -EPERM;
-
         *p += ciphertext_len;
-        return plaintext_len - sizeof(struct ceph_x_encrypt_header);
+        return ret;
 
 e_inval:
         return -EINVAL;