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Add support for dynamic gRPC tables #1530

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merged 4 commits into from
Jan 15, 2025
Merged

Add support for dynamic gRPC tables #1530

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030ce68
add support for dynamic http2 tables
grcevski Jan 15, 2025
566b6d5
only prevent dynamic table indexing on failed index
grcevski Jan 15, 2025
96f08ee
add test for the decoder going out of sync
grcevski Jan 15, 2025
dcc641b
Add integration test
grcevski Jan 15, 2025
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1 change: 1 addition & 0 deletions bpf/http_types.h
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Original file line number Diff line number Diff line change
Expand Up @@ -192,6 +192,7 @@ typedef struct http2_grpc_request {
// with other instrumented processes
pid_info pid;
u8 ssl;
u8 new_conn;
tp_info_t tp;
} http2_grpc_request_t;

Expand Down
9 changes: 6 additions & 3 deletions bpf/k_tracer_defs.h
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Expand Up @@ -42,11 +42,14 @@ static __always_inline void handle_buf_with_args(void *ctx, call_protocol_args_t
bpf_tail_call(ctx, &jump_table, k_tail_protocol_http);
} else if (is_http2_or_grpc(args->small_buf, MIN_HTTP2_SIZE)) {
bpf_dbg_printk("Found HTTP2 or gRPC connection");
u8 is_ssl = args->ssl;
bpf_map_update_elem(&ongoing_http2_connections, &args->pid_conn, &is_ssl, BPF_ANY);
u8 flags = http2_conn_flag_new;
if (args->ssl) {
flags |= http2_conn_flag_ssl;
}
bpf_map_update_elem(&ongoing_http2_connections, &args->pid_conn, &flags, BPF_ANY);
} else {
u8 *h2g = bpf_map_lookup_elem(&ongoing_http2_connections, &args->pid_conn);
if (h2g && *h2g == args->ssl) {
if (h2g && (http2_flag_ssl(*h2g) == args->ssl)) {
bpf_tail_call(ctx, &jump_table, k_tail_protocol_http2);
} else { // large request tracking
http_info_t *info = bpf_map_lookup_elem(&ongoing_http, &args->pid_conn);
Expand Down
20 changes: 19 additions & 1 deletion bpf/protocol_http2.h
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Expand Up @@ -10,10 +10,13 @@
#include "protocol_common.h"
#include "ringbuf.h"

// These are bit flags, if you add any use power of 2 values
enum { http2_conn_flag_ssl = WITH_SSL, http2_conn_flag_new = 0x2 };

struct {
__uint(type, BPF_MAP_TYPE_LRU_HASH);
__type(key, pid_connection_info_t);
__type(value, u8); // ssl or not
__type(value, u8); // flags
__uint(max_entries, MAX_CONCURRENT_REQUESTS);
} ongoing_http2_connections SEC(".maps");

Expand Down Expand Up @@ -62,6 +65,14 @@ static __always_inline grpc_frames_ctx_t *grpc_ctx() {
return bpf_map_lookup_elem(&grpc_frames_ctx_mem, &zero);
}

static __always_inline u8 http2_flag_ssl(u8 flags) {
return flags & http2_conn_flag_ssl;
}

static __always_inline u8 http2_flag_new(u8 flags) {
return flags & http2_conn_flag_new;
}

static __always_inline http2_grpc_request_t *empty_http2_info() {
int zero = 0;
http2_grpc_request_t *value = bpf_map_lookup_elem(&http2_info_mem, &zero);
Expand Down Expand Up @@ -98,6 +109,13 @@ static __always_inline void http2_grpc_start(
h2g_info->pid = meta->pid;
h2g_info->type = meta->type;
}

h2g_info->new_conn = 0;
u8 *h2g = bpf_map_lookup_elem(&ongoing_http2_connections, &s_key->pid_conn);
if (h2g && http2_flag_new(*h2g)) {
h2g_info->new_conn = 1;
}

fixup_connection_info(
&h2g_info->conn_info, h2g_info->type == EVENT_HTTP_CLIENT, orig_dport);
bpf_probe_read(h2g_info->data, KPROBES_HTTP2_BUF_SIZE, u_buf);
Expand Down
20 changes: 15 additions & 5 deletions pkg/internal/ebpf/bhpack/hpack.go
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Expand Up @@ -95,17 +95,21 @@ type Decoder struct {
// to fully parse before. Unlike buf, we own this data.
saveBuf bytes.Buffer

firstField bool // processing the first field of the header block
firstField bool // processing the first field of the header block
lastGoodIndex uint64
failedToIndex bool
}

// NewDecoder returns a new decoder with the provided maximum dynamic
// table size. The emitFunc will be called for each valid field
// parsed, in the same goroutine as calls to Write, before Write returns.
func NewDecoder(maxDynamicTableSize uint32, emitFunc func(f HeaderField)) *Decoder {
d := &Decoder{
emit: emitFunc,
emitEnabled: true,
firstField: true,
emit: emitFunc,
emitEnabled: true,
firstField: true,
failedToIndex: false,
lastGoodIndex: 0,
}
d.dynTab.table.init()
d.dynTab.allowedMaxSize = maxDynamicTableSize
Expand Down Expand Up @@ -345,9 +349,15 @@ func (d *Decoder) parseFieldIndexed() error {
}
hf, ok := d.at(idx)
d.buf = buf
if !ok {
// If we've failed once to find an index, don't allow us to find
// a value for index that's greater than the last successful one
if !ok || (d.failedToIndex && idx > d.lastGoodIndex) {
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did you mean !d.failedToIndex here?

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it should be d.failedToIndex, but I caught a bug with that. I have a new version which changes how this is done now. All I block is adding new entries to the dynamic table. I'll push an update soon once I have integration tests

d.failedToIndex = true
return d.callEmit(HeaderField{Name: "<BAD INDEX>", Value: ""})
}
if idx > d.lastGoodIndex {
d.lastGoodIndex = idx
}
return d.callEmit(HeaderField{Name: hf.Name, Value: hf.Value})
}

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7 changes: 4 additions & 3 deletions pkg/internal/ebpf/common/bpf_arm64_bpfel.go
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4 changes: 2 additions & 2 deletions pkg/internal/ebpf/common/bpf_arm64_bpfel.o
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7 changes: 4 additions & 3 deletions pkg/internal/ebpf/common/bpf_x86_bpfel.go
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38 changes: 25 additions & 13 deletions pkg/internal/ebpf/common/http2grpc_transform.go
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Expand Up @@ -27,6 +27,8 @@ const (
GRPC
)

const initialHeaderTableSize = 4096

type h2Connection struct {
hdec *bhpack.Decoder
hdecRet *bhpack.Decoder
Expand All @@ -45,13 +47,18 @@ func byteFramer(data []uint8) *http2.Framer {
return fr
}

func getOrInitH2Conn(conn *BPFConnInfo) *h2Connection {
func getOrInitH2Conn(conn *BPFConnInfo, newConn bool) *h2Connection {
v, ok := activeGRPCConnections.Get(*conn)

dynamicTableSize := initialHeaderTableSize
if !newConn {
dynamicTableSize = 0
}

if !ok {
h := h2Connection{
hdec: bhpack.NewDecoder(0, nil),
hdecRet: bhpack.NewDecoder(0, nil),
hdec: bhpack.NewDecoder(uint32(dynamicTableSize), nil),
hdecRet: bhpack.NewDecoder(uint32(dynamicTableSize), nil),
protocol: HTTP2,
}
activeGRPCConnections.Add(*conn, h)
Expand All @@ -64,8 +71,8 @@ func getOrInitH2Conn(conn *BPFConnInfo) *h2Connection {
return &v
}

func protocolIsGRPC(conn *BPFConnInfo) {
h2c := getOrInitH2Conn(conn)
func protocolIsGRPC(conn *BPFConnInfo, newConn bool) {
h2c := getOrInitH2Conn(conn, newConn)
if h2c != nil {
h2c.protocol = GRPC
}
Expand Down Expand Up @@ -102,8 +109,8 @@ func knownFrameKeys(fr *http2.Framer, hf *http2.HeadersFrame) bool {
return known
}

func readMetaFrame(conn *BPFConnInfo, fr *http2.Framer, hf *http2.HeadersFrame) (string, string, string, bool) {
h2c := getOrInitH2Conn(conn)
func readMetaFrame(conn *BPFConnInfo, newConn bool, fr *http2.Framer, hf *http2.HeadersFrame) (string, string, string, bool) {
h2c := getOrInitH2Conn(conn, newConn)

ok := false
method := ""
Expand All @@ -126,7 +133,7 @@ func readMetaFrame(conn *BPFConnInfo, fr *http2.Framer, hf *http2.HeadersFrame)
case "content-type":
contentType = strings.ToLower(hf.Value)
if contentType == "application/grpc" {
protocolIsGRPC(conn)
protocolIsGRPC(conn, newConn)
}
ok = true
}
Expand Down Expand Up @@ -162,8 +169,8 @@ func http2grpcStatus(status int) int {
return 2 // Unknown
}

func readRetMetaFrame(conn *BPFConnInfo, fr *http2.Framer, hf *http2.HeadersFrame) (int, bool, bool) {
h2c := getOrInitH2Conn(conn)
func readRetMetaFrame(conn *BPFConnInfo, newConn bool, fr *http2.Framer, hf *http2.HeadersFrame) (int, bool, bool) {
h2c := getOrInitH2Conn(conn, newConn)

ok := false
status := 0
Expand All @@ -184,7 +191,7 @@ func readRetMetaFrame(conn *BPFConnInfo, fr *http2.Framer, hf *http2.HeadersFram
ok = true
case "grpc-status":
status, _ = strconv.Atoi(hf.Value)
protocolIsGRPC(conn)
protocolIsGRPC(conn, newConn)
grpc = true
ok = true
}
Expand Down Expand Up @@ -276,6 +283,11 @@ func http2FromBuffers(event *BPFHTTP2Info) (request.Span, bool, error) {
status := 0
eventType := HTTP2

newConn := true
if event.NewConn == 0 {
newConn = false
}

for {
f, err := framer.ReadFrame()

Expand All @@ -285,7 +297,7 @@ func http2FromBuffers(event *BPFHTTP2Info) (request.Span, bool, error) {

if ff, ok := f.(*http2.HeadersFrame); ok {
rok := false
method, path, contentType, ok := readMetaFrame((*BPFConnInfo)(&event.ConnInfo), framer, ff)
method, path, contentType, ok := readMetaFrame((*BPFConnInfo)(&event.ConnInfo), newConn, framer, ff)

if path == "" {
path = "*"
Expand All @@ -301,7 +313,7 @@ func http2FromBuffers(event *BPFHTTP2Info) (request.Span, bool, error) {
}

if ff, ok := retF.(*http2.HeadersFrame); ok {
status, grpcInStatus, rok = readRetMetaFrame((*BPFConnInfo)(&event.ConnInfo), retFramer, ff)
status, grpcInStatus, rok = readRetMetaFrame((*BPFConnInfo)(&event.ConnInfo), newConn, retFramer, ff)
break
}
}
Expand Down
2 changes: 1 addition & 1 deletion pkg/internal/ebpf/common/http2grpc_transform_test.go
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Expand Up @@ -119,7 +119,7 @@ func TestHTTP2Parsing(t *testing.T) {

if ff, ok := f.(*http2.HeadersFrame); ok {
connInfo := BPFConnInfo{}
method, path, contentType, _ := readMetaFrame(&connInfo, framer, ff)
method, path, contentType, _ := readMetaFrame(&connInfo, false, framer, ff)
assert.Equal(t, method, tt.method)
assert.Equal(t, path, tt.path)
assert.Equal(t, contentType, tt.contentType)
Expand Down
7 changes: 4 additions & 3 deletions pkg/internal/ebpf/generictracer/bpf_arm64_bpfel.go
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7 changes: 4 additions & 3 deletions pkg/internal/ebpf/generictracer/bpf_debug_arm64_bpfel.go
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7 changes: 4 additions & 3 deletions pkg/internal/ebpf/generictracer/bpf_debug_x86_bpfel.go
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7 changes: 4 additions & 3 deletions pkg/internal/ebpf/generictracer/bpf_tp_arm64_bpfel.go
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7 changes: 4 additions & 3 deletions pkg/internal/ebpf/generictracer/bpf_tp_debug_arm64_bpfel.go
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7 changes: 4 additions & 3 deletions pkg/internal/ebpf/generictracer/bpf_tp_debug_x86_bpfel.go
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