Currently, all relayed packets are broken!
At the point when net_key_encrypt() is called from net_rx() for
encrypting a relay packet, the packet size must include the NetMIC
field. But the length of this field has already been removed during
decryption of the incoming packet (by decrypt_net_pkt()), although
mesh_crypto_packet_decrypt() has correctly reset the NetMIC field to
zeroes.
Move stripping of the NetMIC field length from decrypt_net_pkt() to
mesh_crypto_packet_parse(), so that the field length is only stripped
from the payload message (but keeping the field length for the network
PDU). Additionally add extra length checks during parsing.
---
mesh/crypto.c | 21 +++++++++++++++++++++
mesh/net-keys.c | 5 +----
2 files changed, 22 insertions(+), 4 deletions(-)
diff --git a/mesh/crypto.c b/mesh/crypto.c
index 3dcf226ad8d3..a03dc9483862 100644
--- a/mesh/crypto.c
+++ b/mesh/crypto.c
@@ -637,6 +637,9 @@ bool mesh_crypto_packet_parse(const uint8_t *packet, uint8_t packet_len,
if (dst)
*dst = this_dst;
+ if (packet_len < 9 + 4)
+ return false;
+
hdr = l_get_be32(packet + 9);
is_segmented = !!((hdr >> SEG_HDR_SHIFT) & 0x1);
@@ -646,6 +649,9 @@ bool mesh_crypto_packet_parse(const uint8_t *packet, uint8_t packet_len,
if (*ctl) {
uint8_t this_opcode = packet[9] & OPCODE_MASK;
+ /* NetMIC */
+ packet_len -= 8;
+
if (cookie)
*cookie = l_get_be32(packet + 2) ^ packet[6];
@@ -660,13 +666,22 @@ bool mesh_crypto_packet_parse(const uint8_t *packet, uint8_t packet_len,
*seqZero = (hdr >> SEQ_ZERO_HDR_SHIFT) &
SEQ_ZERO_MASK;
+ if (packet_len < 9)
+ return false;
+
*payload = packet + 9;
*payload_len = packet_len - 9;
} else {
+ if (packet_len < 10)
+ return false;
+
*payload = packet + 10;
*payload_len = packet_len - 10;
}
} else {
+ /* NetMIC */
+ packet_len -= 4;
+
if (cookie)
*cookie = l_get_be32(packet + packet_len - 8);
@@ -687,9 +702,15 @@ bool mesh_crypto_packet_parse(const uint8_t *packet, uint8_t packet_len,
if (segN)
*segN = (hdr >> SEGN_HDR_SHIFT) & SEG_MASK;
+ if (packet_len < 13)
+ return false;
+
*payload = packet + 13;
*payload_len = packet_len - 13;
} else {
+ if (packet_len < 10)
+ return false;
+
*payload = packet + 10;
*payload_len = packet_len - 10;
}
diff --git a/mesh/net-keys.c b/mesh/net-keys.c
index 0daeb9209b86..98e6d23d3f87 100644
--- a/mesh/net-keys.c
+++ b/mesh/net-keys.c
@@ -238,10 +238,7 @@ static void decrypt_net_pkt(void *a, void *b)
if (result) {
cache_id = key->id;
- if (cache_plain[1] & 0x80)
- cache_plainlen = cache_len - 8;
- else
- cache_plainlen = cache_len - 4;
+ cache_plainlen = cache_len;
}
}
--
2.43.0
