Check that signature data lengths do not exceed the available data

[onak.git] / decodekey.c

diff --git a/decodekey.c b/decodekey.c
index 57a1e660754b1a7adf79284d028f248d23416b6d..522ad901383dd6a217b0ef5ed2320a93e3d51f8b 100644 (file)
--- a/decodekey.c
+++ b/decodekey.c
@@ -34,6 +34,8 @@
 /*
  *     parse_subpackets - Parse the subpackets of a Type 4 signature.
  *     @data: The subpacket data.
+ *     @len: The amount of data available to read.
+ *     @parselen: The amount of data that was actually parsed.
  *     @keyid: A pointer to where we should return the keyid.
  *     @creationtime: A pointer to where we should return the creation time.
  *
@@ -42,7 +44,8 @@
  *     processed. If the value of any piece of data is not desired a NULL
  *     can be passed instead of a pointer to a storage area for that value.
  */
-int parse_subpackets(unsigned char *data, uint64_t *keyid, time_t *creation)
+onak_status_t parse_subpackets(unsigned char *data, size_t len,
+               size_t *parselen, uint64_t *keyid, time_t *creation)
 {
        int offset = 0;
        int length = 0;
@@ -50,8 +53,20 @@ int parse_subpackets(unsigned char *data, uint64_t *keyid, time_t *creation)
 
        log_assert(data != NULL);
 
+       /* Make sure we actually have the 2 byte length field */
+       if (len < 2) {
+               return ONAK_E_INVALID_PKT;
+       }
+
        length = (data[0] << 8) + data[1] + 2;
 
+       /* If the length is off the end of the data available, it's bogus */
+       if (len < length) {
+               return ONAK_E_INVALID_PKT;
+       }
+
+       *parselen = length;
+
        offset = 2;
        while (offset < length) {
                packetlen = data[offset++];
@@ -152,7 +167,7 @@ int parse_subpackets(unsigned char *data, uint64_t *keyid, time_t *creation)
                offset += packetlen;
        }
 
-       return length;
+       return ONAK_E_OK;
 }
 
 /**
@@ -187,10 +202,12 @@ struct ll *keysigs(struct ll *curll,
  *     key or pulls the data directly from v2/3. NULL can be passed for any
  *     values which aren't cared about.
  */
-void sig_info(struct openpgp_packet *packet, uint64_t *keyid, time_t *creation)
+onak_status_t sig_info(struct openpgp_packet *packet, uint64_t *keyid,
+               time_t *creation)
 {
-       int length = 0;
-       
+       size_t length = 0;
+       onak_status_t res;
+
        if (packet != NULL) {
                switch (packet->data[0]) {
                case 2:
@@ -223,20 +240,25 @@ void sig_info(struct openpgp_packet *packet, uint64_t *keyid, time_t *creation)
                        }
                        break;
                case 4:
-                       length = parse_subpackets(&packet->data[4],
-                                       keyid, creation);
-                       parse_subpackets(&packet->data[length + 4],
-                                       keyid, creation);
-                       /*
-                        * Don't bother to look at the unsigned packets.
-                        */
+                       res = parse_subpackets(&packet->data[4],
+                                       packet->length - 4,
+                                       &length, keyid, creation);
+                       if (res != ONAK_E_OK) {
+                               return res;
+                       }
+                       res = parse_subpackets(&packet->data[length + 4],
+                                       packet->length - (4 + length),
+                                       &length, keyid, creation);
+                       if (res != ONAK_E_OK) {
+                               return res;
+                       }
                        break;
                default:
                        break;
                }
        }
 
-       return;
+       return ONAK_E_OK;
 }
 
 /**