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Kernel: Do some basic sanity checking on IPv4 packet headers

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Ignore packets that are too small, or not as large as they claim to be.
This commit is contained in:
Andreas Kling 2019-08-09 09:36:06 +02:00
parent 04603237da
commit 9e2a00248e
1 changed files with 16 additions and 2 deletions
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18
Kernel/Net/NetworkTask.cpp
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@ -72,8 +72,8 @@ void NetworkTask_main()
continue; continue;
} }
auto& packet = packet_maybe_null.value(); auto& packet = packet_maybe_null.value();
if (packet.size() < (int)(sizeof(EthernetFrameHeader))) { if (packet.size() < sizeof(EthernetFrameHeader)) {
kprintf("NetworkTask: Packet is too small to be an Ethernet packet! (%d)\n", packet.size()); kprintf("NetworkTask: Packet is too small to be an Ethernet packet! (%zu)\n", packet.size());
continue; continue;
} }
auto& eth = *(const EthernetFrameHeader*)packet.data(); auto& eth = *(const EthernetFrameHeader*)packet.data();
@ -185,10 +185,24 @@ void handle_ipv4(const EthernetFrameHeader& eth, int frame_size)
constexpr int minimum_ipv4_frame_size = sizeof(EthernetFrameHeader) + sizeof(IPv4Packet); constexpr int minimum_ipv4_frame_size = sizeof(EthernetFrameHeader) + sizeof(IPv4Packet);
if (frame_size < minimum_ipv4_frame_size) { if (frame_size < minimum_ipv4_frame_size) {
kprintf("handle_ipv4: Frame too small (%d, need %d)\n", frame_size, minimum_ipv4_frame_size); kprintf("handle_ipv4: Frame too small (%d, need %d)\n", frame_size, minimum_ipv4_frame_size);
hang();
return; return;
} }
auto& packet = *static_cast<const IPv4Packet*>(eth.payload()); auto& packet = *static_cast<const IPv4Packet*>(eth.payload());
if (packet.length() < sizeof(IPv4Packet)) {
kprintf("handle_ipv4: IPv4 packet too short (%u, need %u)\n", packet.length(), sizeof(IPv4Packet));
hang();
return;
}
size_t actual_ipv4_packet_length = frame_size - sizeof(EthernetFrameHeader);
if (packet.length() > actual_ipv4_packet_length) {
kprintf("handle_ipv4: IPv4 packet claims to be longer than it is (%u, actually %zu)\n", packet.length(), actual_ipv4_packet_length);
hang();
return;
}
#ifdef IPV4_DEBUG #ifdef IPV4_DEBUG
kprintf("handle_ipv4: source=%s, target=%s\n", kprintf("handle_ipv4: source=%s, target=%s\n",
packet.source().to_string().characters(), packet.source().to_string().characters(),