Fix harcoded offset bug in grpc-go (#763)

grafana · Apr 19, 2024 · e36cd60 · e36cd60
1 parent 6bf78e9
commit e36cd60
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Showing 6 changed files with 3 additions and 10 deletions.
diff --git a/bpf/go_grpc.c b/bpf/go_grpc.c
@@ -449,7 +449,7 @@ int uprobe_grpcFramerWriteHeaders(struct pt_regs *ctx) {
     void *framer = GO_PARAM1(ctx);
     u64 stream_id = (u64)GO_PARAM2(ctx);
 
-    bpf_printk("framer=%llx, stream_id=%lld", framer, ((u64)stream_id));
+    bpf_printk("framer=%llx, stream_id=%lld, framer_w_pos %llx", framer, ((u64)stream_id), framer_w_pos);
 
     u32 stream_lookup = (u32)stream_id;
 
@@ -549,7 +549,7 @@ int uprobe_grpcFramerWriteHeaders_returns(struct pt_regs *ctx) {
                 bpf_probe_write_user(buf_arr + (n & 0x0ffff), tp_str, sizeof(tp_str));
                 n += TP_MAX_VAL_LENGTH;
                 // Update the value of n in w to reflect the new size
-                bpf_probe_write_user((void *)(w_ptr + 32), &n, sizeof(n));
+                bpf_probe_write_user((void *)(w_ptr + grpc_transport_buf_writer_offset_pos), &n, sizeof(n));
 
                 // http2 encodes the length of the headers in the first 3 bytes of buf, we need to update those
                 u8 size_1 = 0;

diff --git a/pkg/internal/ebpf/grpc/bpf_tp_bpfel_arm64.o b/pkg/internal/ebpf/grpc/bpf_tp_bpfel_arm64.o
diff --git a/pkg/internal/ebpf/grpc/bpf_tp_bpfel_x86.o b/pkg/internal/ebpf/grpc/bpf_tp_bpfel_x86.o
diff --git a/pkg/internal/ebpf/grpc/bpf_tp_debug_bpfel_arm64.o b/pkg/internal/ebpf/grpc/bpf_tp_debug_bpfel_arm64.o
diff --git a/pkg/internal/ebpf/grpc/bpf_tp_debug_bpfel_x86.o b/pkg/internal/ebpf/grpc/bpf_tp_debug_bpfel_x86.o
diff --git a/pkg/internal/ebpf/grpc/grpc.go b/pkg/internal/ebpf/grpc/grpc.go
@@ -110,14 +110,7 @@ func (p *Tracer) Constants(_ *exec.FileInfo, offsets *goexec.Offsets) map[string
 		"fd_laddr_pos",
 		"fd_raddr_pos",
 	} {
-		// Since gRPC 1.60 remoteaddr and localaddr were replaced by peer.
-		// We don't fail the store of unknown fields, we make them -1 so we detect
-		// what to read from the Go structures.
-		if off, ok := offsets.Field[s]; ok {
-			constants[s] = off
-		} else {
-			constants[s] = uint64(0xffffffffffffffff)
-		}
+		constants[s] = offsets.Field[s]
 	}
 	return constants
 }