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Use correct byte ordering function for kernel struct member (skc_num) #2002

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Sep 16, 2024
Merged

Use correct byte ordering function for kernel struct member (skc_num) #2002

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14 changes: 8 additions & 6 deletions src/stirling/source_connectors/tcp_stats/bcc_bpf/tcp_stats.c
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Original file line number Diff line number Diff line change
Expand Up @@ -79,12 +79,12 @@ static int tcp_sendstat(struct pt_regs* ctx, uint32_t tgid, uint32_t id, int siz
event.upid.start_time_ticks = get_tgid_start_time();

if (family == AF_INET) {
event.local_addr.in4.sin_port = ntohs(lport);
event.local_addr.in4.sin_port = htons(lport);
event.remote_addr.in4.sin_port = rport;
BPF_PROBE_READ_KERNEL_VAR(event.local_addr.in4.sin_addr.s_addr, &sk_common->skc_rcv_saddr);
BPF_PROBE_READ_KERNEL_VAR(event.remote_addr.in4.sin_addr.s_addr, &sk_common->skc_daddr);
} else if (family == AF_INET6) {
event.local_addr.in6.sin6_port = ntohs(lport);
event.local_addr.in6.sin6_port = htons(lport);
event.remote_addr.in6.sin6_port = rport;
BPF_PROBE_READ_KERNEL_VAR(event.local_addr.in6.sin6_addr, &sk_common->skc_v6_rcv_saddr);
BPF_PROBE_READ_KERNEL_VAR(event.remote_addr.in6.sin6_addr, &sk_common->skc_v6_daddr);
Expand Down Expand Up @@ -158,12 +158,12 @@ int probe_entry_tcp_cleanup_rbuf(struct pt_regs* ctx, struct sock* sk, int copie
event.local_addr.sa.sa_family = family;

if (family == AF_INET) {
event.local_addr.in4.sin_port = ntohs(lport);
event.local_addr.in4.sin_port = htons(lport);
event.remote_addr.in4.sin_port = rport;
BPF_PROBE_READ_KERNEL_VAR(event.local_addr.in4.sin_addr.s_addr, &sk->__sk_common.skc_rcv_saddr);
BPF_PROBE_READ_KERNEL_VAR(event.remote_addr.in4.sin_addr.s_addr, &sk->__sk_common.skc_daddr);
} else if (family == AF_INET6) {
event.local_addr.in6.sin6_port = ntohs(lport);
event.local_addr.in6.sin6_port = htons(lport);
event.remote_addr.in6.sin6_port = rport;
BPF_PROBE_READ_KERNEL_VAR(event.local_addr.in6.sin6_addr, &sk->__sk_common.skc_v6_rcv_saddr);
BPF_PROBE_READ_KERNEL_VAR(event.remote_addr.in6.sin6_addr, &sk->__sk_common.skc_v6_daddr);
Expand Down Expand Up @@ -196,6 +196,8 @@ int probe_entry_tcp_retransmit_skb(struct pt_regs* ctx, struct sock* skp, struct

int lport = -1;
int rport = -1;
// skc_num is stored in host byte order. The rest of our user space processing
// assumes network byte order so convert it here.
BPF_PROBE_READ_KERNEL_VAR(lport, &skp->__sk_common.skc_num);
BPF_PROBE_READ_KERNEL_VAR(rport, &skp->__sk_common.skc_dport);

Expand All @@ -204,13 +206,13 @@ int probe_entry_tcp_retransmit_skb(struct pt_regs* ctx, struct sock* skp, struct
event.local_addr.sa.sa_family = family;

if (family == AF_INET) {
event.local_addr.in4.sin_port = ntohs(lport);
event.local_addr.in4.sin_port = htons(lport);
event.remote_addr.in4.sin_port = rport;
BPF_PROBE_READ_KERNEL_VAR(event.local_addr.in4.sin_addr.s_addr,
&skp->__sk_common.skc_rcv_saddr);
BPF_PROBE_READ_KERNEL_VAR(event.remote_addr.in4.sin_addr.s_addr, &skp->__sk_common.skc_daddr);
} else if (family == AF_INET6) {
event.local_addr.in6.sin6_port = ntohs(lport);
event.local_addr.in6.sin6_port = htons(lport);
event.remote_addr.in6.sin6_port = rport;
BPF_PROBE_READ_KERNEL_VAR(event.local_addr.in6.sin6_addr, &skp->__sk_common.skc_v6_rcv_saddr);
BPF_PROBE_READ_KERNEL_VAR(event.remote_addr.in6.sin6_addr, &skp->__sk_common.skc_v6_daddr);
Expand Down
3 changes: 3 additions & 0 deletions src/stirling/source_connectors/tcp_stats/tcp_stats_bpf_test.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -123,6 +123,9 @@ TEST_F(TcpTraceTest, Capture) {
EXPECT_THAT(records, IsSupersetOf(expected));
// TODO(RagalahariP): Explore options for testing retransmissions in a unit test case,
// as retransmissions are blocking calls without known timeout value.

// TODO(ddelnano): Use a test case that verifies that local address of the socket is correct.
// The current implementation is correct, but other source connectors have had bugs here.
}

} // namespace stirling
Expand Down
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