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fix(ebpf): flag events lost to a failed copy, and mark TLS on the tracked connection #367

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Merged
blue4209211 merged 2 commits into from
Oct 6, 2026
+39 −29
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fix(ebpf): flag events lost to a failed copy, and mark TLS on the tracked connection #367

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929db7b
fix(ebpf): flag events lost to a failed copy, and mark TLS on the tra…
mayankpande88 Oct 6, 2026
3c893ed
refactor(ebpf): drop COPY_PAYLOAD_RINGBUF's unused event parameter
mayankpande88 Oct 6, 2026
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20 changes: 10 additions & 10 deletions ebpftracer/ebpf.go
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48 changes: 29 additions & 19 deletions ebpftracer/ebpf/l7/l7.c
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Original file line number Diff line number Diff line change
Expand Up @@ -56,13 +56,20 @@
} \
})

// COPY_PAYLOAD_RINGBUF copies a payload into an event from reserve_l7_event
// and returns 0 (dropping the event) if the read fails.
#define COPY_PAYLOAD_RINGBUF(e, dst, size, src) ({ \
TRUNCATE_COPY_SIZE(size); \
if (bpf_probe_read(dst, size, src)) { \
return 0; \
} \
// connection.l7_lost bits: events lost on the written and read side.
#define L7_LOST_WRITES 1
#define L7_LOST_READS 2

// COPY_PAYLOAD_RINGBUF copies a payload into an event from reserve_l7_event.
// If the read fails the event is dropped (returns 0), and the loss is
// recorded on the connection as send_event records a full ring buffer, so a
// stateful parser learns of the gap.
#define COPY_PAYLOAD_RINGBUF(conn, lost, dst, size, src) ({ \
TRUNCATE_COPY_SIZE(size); \
if (bpf_probe_read(dst, size, src)) { \
(conn)->l7_lost |= (lost); \
return 0; \
} \
})

#define IOVEC_BUF_SIZE MAX_PAYLOAD_SIZE * 2 // must be double of MAX_PAYLOAD_SIZE
Expand Down Expand Up @@ -313,7 +320,7 @@ void send_event(void *ctx, struct l7_event *e, struct connection_id cid, struct
if (drops) {
*drops += 1;
}
conn->l7_lost |= e->method == METHOD_HTTP2_SERVER_FRAMES ? 2 : 1;
conn->l7_lost |= e->method == METHOD_HTTP2_SERVER_FRAMES ? L7_LOST_READS : L7_LOST_WRITES;
} else if (e->lost_before) {
conn->l7_lost = 0;
}
Expand Down Expand Up @@ -588,6 +595,9 @@ int trace_enter_write(void *ctx, __u64 fd, __u16 is_tls, char *buf, __u64 size,
struct connection *tracked = bpf_map_lookup_elem(&active_connections, &cid);
if (tracked) {
conn = tracked;
// If another CPU inserted it first (the TCP connect path
// does, with tls 0), the mark above went to the stack copy.
mark_tls(conn);
}
}
} else if (conn->tls) {
Expand Down Expand Up @@ -638,7 +648,7 @@ int trace_enter_write(void *ctx, __u64 fd, __u16 is_tls, char *buf, __u64 size,
e->method = METHOD_HTTP2_CLIENT_FRAMES;
e->duration = bpf_ktime_get_ns();
e->payload_size = size;
COPY_PAYLOAD_RINGBUF(e, e->payload, size, payload);
COPY_PAYLOAD_RINGBUF(conn, L7_LOST_WRITES, e->payload, size, payload);
send_event(ctx, e, cid, conn);
if (is_tls) { bpf_printk("l7_H2_SENT: pid=%u fd=%llu size=%llu", cid.pid, fd, size); }
return 0;
Expand All @@ -655,7 +665,7 @@ int trace_enter_write(void *ctx, __u64 fd, __u16 is_tls, char *buf, __u64 size,
e->method = 0;
e->duration = bpf_ktime_get_ns();
e->payload_size = size;
COPY_PAYLOAD_RINGBUF(e, e->payload, size, payload);
COPY_PAYLOAD_RINGBUF(conn, L7_LOST_WRITES, e->payload, size, payload);
send_event(ctx, e, cid, conn);
return 0;
}
Expand All @@ -682,7 +692,7 @@ int trace_enter_write(void *ctx, __u64 fd, __u16 is_tls, char *buf, __u64 size,
e->method = METHOD_HTTP2_CLIENT_FRAMES;
e->duration = bpf_ktime_get_ns();
e->payload_size = size;
COPY_PAYLOAD_RINGBUF(e, e->payload, size, payload);
COPY_PAYLOAD_RINGBUF(conn, L7_LOST_WRITES, e->payload, size, payload);
send_event(ctx, e, cid, conn);
return 0;
}
Expand Down Expand Up @@ -726,7 +736,7 @@ int trace_enter_write(void *ctx, __u64 fd, __u16 is_tls, char *buf, __u64 size,
e->method = METHOD_HTTP2_CLIENT_FRAMES;
e->duration = bpf_ktime_get_ns();
e->payload_size = size;
COPY_PAYLOAD_RINGBUF(e, e->payload, size, payload);
COPY_PAYLOAD_RINGBUF(conn, L7_LOST_WRITES, e->payload, size, payload);
send_event(ctx, e, cid, conn);
return 0;
} else if (conn->dport == 5672 && (is_rabbitmq_connection(payload, size) || is_amqp_frame(payload, size) || is_amqp_method_frame(payload, size))) {
Expand Down Expand Up @@ -761,7 +771,7 @@ int trace_enter_write(void *ctx, __u64 fd, __u16 is_tls, char *buf, __u64 size,
e->protocol = PROTOCOL_POSTGRES;
e->method = METHOD_STATEMENT_CLOSE;
e->payload_size = size;
COPY_PAYLOAD_RINGBUF(e, e->payload, size, payload);
COPY_PAYLOAD_RINGBUF(conn, L7_LOST_WRITES, e->payload, size, payload);
send_event(ctx, e, cid, conn);
return 0;
}
Expand All @@ -771,7 +781,7 @@ int trace_enter_write(void *ctx, __u64 fd, __u16 is_tls, char *buf, __u64 size,
e->protocol = PROTOCOL_MYSQL;
e->method = METHOD_STATEMENT_CLOSE;
e->payload_size = size;
COPY_PAYLOAD_RINGBUF(e, e->payload, size, payload);
COPY_PAYLOAD_RINGBUF(conn, L7_LOST_WRITES, e->payload, size, payload);
send_event(ctx, e, cid, conn);
return 0;
}
Expand Down Expand Up @@ -906,7 +916,7 @@ int trace_exit_read(void *ctx, __u64 id, __u32 pid, __u16 is_tls, long int ret)
e->method = METHOD_HTTP2_SERVER_FRAMES;
e->duration = bpf_ktime_get_ns();
e->payload_size = ret;
COPY_PAYLOAD_RINGBUF(e, e->payload, ret, payload);
COPY_PAYLOAD_RINGBUF(conn, L7_LOST_READS, e->payload, ret, payload);
send_event(ctx, e, cid, conn);
return 0;
}
Expand All @@ -923,7 +933,7 @@ int trace_exit_read(void *ctx, __u64 id, __u32 pid, __u16 is_tls, long int ret)
e->protocol = PROTOCOL_DNS;
e->duration = bpf_ktime_get_ns() - req->ns;
e->payload_size = ret;
COPY_PAYLOAD_RINGBUF(e, e->payload, ret, payload);
COPY_PAYLOAD_RINGBUF(conn, L7_LOST_READS, e->payload, ret, payload);
send_event(ctx, e, cid, conn);
bpf_map_delete_elem(&active_l7_requests, &k);
return 0;
Expand All @@ -941,7 +951,7 @@ int trace_exit_read(void *ctx, __u64 id, __u32 pid, __u16 is_tls, long int ret)
e->method = METHOD_HTTP2_SERVER_FRAMES;
e->duration = bpf_ktime_get_ns();
e->payload_size = ret;
COPY_PAYLOAD_RINGBUF(e, e->payload, ret, payload);
COPY_PAYLOAD_RINGBUF(conn, L7_LOST_READS, e->payload, ret, payload);
send_event(ctx, e, cid, conn);
return 0;
} else {
Expand All @@ -952,7 +962,7 @@ int trace_exit_read(void *ctx, __u64 id, __u32 pid, __u16 is_tls, long int ret)

e->protocol = req->protocol;
e->payload_size = req->payload_size;
COPY_PAYLOAD_RINGBUF(e, e->payload, req->payload_size, req->payload);
COPY_PAYLOAD_RINGBUF(conn, L7_LOST_READS, e->payload, req->payload_size, req->payload);
if (e->protocol == PROTOCOL_HTTP) {
response = is_http_response(payload, &e->status);
} else if (e->protocol == PROTOCOL_POSTGRES) {
Expand Down Expand Up @@ -1007,7 +1017,7 @@ int trace_exit_read(void *ctx, __u64 id, __u32 pid, __u16 is_tls, long int ret)
}
e->duration = bpf_ktime_get_ns() - req->ns;
e->response_size = ret;
COPY_PAYLOAD_RINGBUF(e, e->response, ret, payload);
COPY_PAYLOAD_RINGBUF(conn, L7_LOST_READS, e->response, ret, payload);
send_event(ctx, e, cid, conn);
return 0;
}
Expand Down
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