diff options
author | Maciej Żenczykowski <maze@google.com> | 2023-03-15 00:51:54 +0000 |
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committer | Maciej Żenczykowski <maze@google.com> | 2023-03-15 01:16:12 +0000 |
commit | aae2fb956c405449ba76827fa558ef440bd890f9 (patch) | |
tree | 32a8381b82e2a856551198cc35c17a9034ff9cb5 | |
parent | 1afdff720473aaba38ff824e83ad19c90195960f (diff) | |
download | android-clat-aae2fb956c405449ba76827fa558ef440bd890f9.tar.gz |
clatd: perform checksum calculation when required
Test: TreeHugger
Bug: 265591307
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: Ia0188a34d26eeffadbdbfd5a9c8fe3427f4eba98
-rw-r--r-- | clatd.c | 26 |
1 files changed, 22 insertions, 4 deletions
@@ -128,21 +128,39 @@ void process_packet_6_to_4(struct tun_data *tunnel) { } if (readlen < sizeof(struct virtio_net_hdr) + tp_net) { - logmsg(ANDROID_LOG_WARN, "%s: ignoring %zd byte pkt shorter than %u L2 header", - __func__, readlen, tp_net); + logmsg(ANDROID_LOG_WARN, "%s: ignoring %zd byte pkt shorter than %zu+%u L2 header", + __func__, readlen, sizeof(struct virtio_net_hdr), tp_net); return; } + const int pkt_len = readlen - sizeof(struct virtio_net_hdr); + // This will detect a skb->ip_summed == CHECKSUM_PARTIAL packet with non-final L4 checksum if (tp_status & TP_STATUS_CSUMNOTREADY) { static bool logged = false; if (!logged) { - logmsg(ANDROID_LOG_WARN, "read_packet checksum not ready"); + logmsg(ANDROID_LOG_WARN, "%s: L4 checksum calculation required", __func__); logged = true; } + + // These are non-negative by virtue of csum_start/offset being u16 + const int cs_start = buf.vnet.csum_start; + const int cs_offset = cs_start + buf.vnet.csum_offset; + if (cs_start > pkt_len) { + logmsg(ANDROID_LOG_ERROR, "%s: out of range - checksum start %d > %d", + __func__, cs_start, pkt_len); + } else if (cs_offset + 1 >= pkt_len) { + logmsg(ANDROID_LOG_ERROR, "%s: out of range - checksum offset %d + 1 >= %d", + __func__, cs_offset, pkt_len); + } else { + uint16_t csum = ip_checksum(buf.payload + cs_start, pkt_len - cs_start); + if (!csum) csum = 0xFFFF; // required fixup for UDP, TCP must live with it + buf.payload[cs_offset] = csum & 0xFF; + buf.payload[cs_offset + 1] = csum >> 8; + } } - translate_packet(tunnel->fd4, 0 /* to_ipv6 */, buf.payload + tp_net, readlen - sizeof(struct virtio_net_hdr) - tp_net); + translate_packet(tunnel->fd4, 0 /* to_ipv6 */, buf.payload + tp_net, pkt_len - tp_net); } // reads TUN_PI + L3 IPv4 packet from tun, translates to IPv6, writes to AF_INET6/RAW socket |