QUIC: added BPF packet data fallback

Use bpf_skb_load_bytes() in the reuseport BPF helper when the required
QUIC header bytes are not available through direct packet access.  This
keeps the direct access fast path while allowing the helper to parse the
flags byte, DCID length byte, and DCID key from non linear skb data.

A similar approach was implemented in [1].

[1] https://git.angie.software/web-server/angie/commit/4b527f5

diff --git a/src/event/quic/bpf/ngx_quic_reuseport_helper.c b/src/event/quic/bpf/ngx_quic_reuseport_helper.c
index 51b78f043600d1c3315f4bf52ca3f9343b033aab..cf7a24c5a6bcf4fdfd4c6873fe59c81c0702f355 100644 (file)
--- a/src/event/quic/bpf/ngx_quic_reuseport_helper.c
+++ b/src/event/quic/bpf/ngx_quic_reuseport_helper.c
@@ -44,15 +44,6 @@ char _license[] SEC("license") = LICENSE;
 #define NGX_QUIC_SERVER_CID_LEN  20
 
 
-#define advance_data(nbytes)                                                  \
-    offset += nbytes;                                                         \
-    if (start + offset > end) {                                               \
-        debugmsg("cannot read %ld bytes at offset %ld", nbytes, offset);      \
-        goto failed;                                                          \
-    }                                                                         \
-    data = start + offset - 1;
-
-
 #define ngx_quic_parse_uint64(p)                                              \
     (((__u64)(p)[0] << 56) |                                                  \
      ((__u64)(p)[1] << 48) |                                                  \
@@ -75,38 +66,54 @@ int ngx_quic_select_socket_by_dcid(struct sk_reuseport_md *ctx)
 {
     int             rc;
     __u64           key;
-    size_t          len, offset;
-    unsigned char  *start, *end, *data, *dcid;
+    size_t          offset;
+    unsigned char  *start, *end, *dcid, byte, buf[NGX_QUIC_SERVER_CID_LEN];
 
-    start = ctx->data;
+    start = (unsigned char *) ctx->data;
     end = (unsigned char *) ctx->data_end;
-    offset = 0;
+    offset = sizeof(struct udphdr);
 
-    advance_data(sizeof(struct udphdr)); /* data at UDP header */
-    advance_data(1); /* data at QUIC flags */
+    if (start + offset >= end) {
 
-    if (data[0] & NGX_QUIC_PKT_LONG) {
+        if (bpf_skb_load_bytes(ctx, offset, &byte, 1)) {
+            goto failed;
+        }
 
-        advance_data(4); /* data at QUIC version */
-        advance_data(1); /* data at DCID len */
+    } else {
+        byte = start[offset];
+    }
 
-        len = data[0];   /* read DCID length */
+    if (byte & NGX_QUIC_PKT_LONG) {
 
-        if (len < 8) {
-            /* it's useless to search for key in such short DCID */
-            return SK_PASS;
+        offset += 5;
+
+        if (start + offset >= end) {
+
+            if (bpf_skb_load_bytes(ctx, offset, &byte, 1)) {
+                goto failed;
+            }
+
+        } else {
+            byte = start[offset];
         }
 
-    } else {
-        len = NGX_QUIC_SERVER_CID_LEN;
+        if (byte != NGX_QUIC_SERVER_CID_LEN) {
+            return SK_PASS;
+        }
     }
 
-    dcid = &data[1];
-    advance_data(len); /* we expect the packet to have full DCID */
+    offset++;
 
-    /* make verifier happy */
-    if (dcid + sizeof(__u64) > end) {
-        goto failed;
+    if (start + offset + NGX_QUIC_SERVER_CID_LEN > end) {
+
+        if (bpf_skb_load_bytes(ctx, offset, buf, NGX_QUIC_SERVER_CID_LEN)) {
+            goto failed;
+        }
+
+        dcid = buf;
+
+    } else {
+        dcid = start + offset;
     }
 
     key = ngx_quic_parse_uint64(dcid);

diff --git a/src/event/quic/ngx_event_quic_bpf_code.c b/src/event/quic/ngx_event_quic_bpf_code.c
index 625f404056d9bd02e5757305a09f39b637b2b659..e32f1c68eadaccac58e3b13ea085ae4e0d1acb39 100644 (file)
--- a/src/event/quic/ngx_event_quic_bpf_code.c
+++ b/src/event/quic/ngx_event_quic_bpf_code.c
@@ -7,70 +7,88 @@
 
 
 static ngx_bpf_reloc_t bpf_reloc_prog_ngx_quic_reuseport_helper[] = {
-    { "ngx_quic_sockmap", 59 },
+    { "ngx_quic_sockmap", 77 },
 };
 
 static struct bpf_insn bpf_insn_prog_ngx_quic_reuseport_helper[] = {
     /* opcode dst          src         offset imm */
-    { 0x79,   BPF_REG_2,   BPF_REG_1, (int16_t)      0,        0x0 },
-    { 0x79,   BPF_REG_3,   BPF_REG_1, (int16_t)      8,        0x0 },
-    { 0xbf,   BPF_REG_6,   BPF_REG_2, (int16_t)      0,        0x0 },
-    {  0x7,   BPF_REG_6,   BPF_REG_0, (int16_t)      0,        0x8 },
-    { 0x2d,   BPF_REG_6,   BPF_REG_3, (int16_t)     58,        0x0 },
-    { 0xbf,   BPF_REG_4,   BPF_REG_2, (int16_t)      0,        0x0 },
-    {  0x7,   BPF_REG_4,   BPF_REG_0, (int16_t)      0,        0x9 },
-    { 0x2d,   BPF_REG_4,   BPF_REG_3, (int16_t)     55,        0x0 },
-    { 0xb7,   BPF_REG_4,   BPF_REG_0, (int16_t)      0,        0x8 },
-    { 0xb7,   BPF_REG_5,   BPF_REG_0, (int16_t)      0,       0x14 },
-    { 0xb7,   BPF_REG_0,   BPF_REG_0, (int16_t)      0,        0x9 },
-    { 0x71,   BPF_REG_6,   BPF_REG_6, (int16_t)      0,        0x0 },
-    { 0x67,   BPF_REG_6,   BPF_REG_0, (int16_t)      0,       0x38 },
-    { 0xc7,   BPF_REG_6,   BPF_REG_0, (int16_t)      0,       0x38 },
-    { 0x65,   BPF_REG_6,   BPF_REG_0, (int16_t)     11, 0xffffffff },
-    { 0xbf,   BPF_REG_5,   BPF_REG_2, (int16_t)      0,        0x0 },
-    {  0x7,   BPF_REG_5,   BPF_REG_0, (int16_t)      0,        0xd },
-    { 0x2d,   BPF_REG_5,   BPF_REG_3, (int16_t)     45,        0x0 },
-    { 0xbf,   BPF_REG_4,   BPF_REG_2, (int16_t)      0,        0x0 },
-    {  0x7,   BPF_REG_4,   BPF_REG_0, (int16_t)      0,        0xe },
-    { 0x2d,   BPF_REG_4,   BPF_REG_3, (int16_t)     42,        0x0 },
-    { 0xb7,   BPF_REG_4,   BPF_REG_0, (int16_t)      0,        0xd },
-    { 0xb7,   BPF_REG_0,   BPF_REG_0, (int16_t)      0,        0xe },
-    { 0x71,   BPF_REG_5,   BPF_REG_5, (int16_t)      0,        0x0 },
-    { 0xb7,   BPF_REG_6,   BPF_REG_0, (int16_t)      0,        0x8 },
-    { 0x2d,   BPF_REG_6,   BPF_REG_5, (int16_t)     37,        0x0 },
-    { 0xbf,   BPF_REG_6,   BPF_REG_2, (int16_t)      0,        0x0 },
-    {  0xf,   BPF_REG_6,   BPF_REG_0, (int16_t)      0,        0x0 },
-    {  0xf,   BPF_REG_6,   BPF_REG_5, (int16_t)      0,        0x0 },
-    { 0x2d,   BPF_REG_6,   BPF_REG_3, (int16_t)     33,        0x0 },
-    {  0xf,   BPF_REG_2,   BPF_REG_4, (int16_t)      0,        0x0 },
-    { 0xbf,   BPF_REG_4,   BPF_REG_2, (int16_t)      0,        0x0 },
-    {  0x7,   BPF_REG_4,   BPF_REG_0, (int16_t)      0,        0x9 },
-    { 0x2d,   BPF_REG_4,   BPF_REG_3, (int16_t)     29,        0x0 },
-    { 0x71,   BPF_REG_4,   BPF_REG_2, (int16_t)      1,        0x0 },
-    { 0x67,   BPF_REG_4,   BPF_REG_0, (int16_t)      0,       0x38 },
-    { 0x71,   BPF_REG_3,   BPF_REG_2, (int16_t)      2,        0x0 },
-    { 0x67,   BPF_REG_3,   BPF_REG_0, (int16_t)      0,       0x30 },
-    { 0x4f,   BPF_REG_3,   BPF_REG_4, (int16_t)      0,        0x0 },
-    { 0x71,   BPF_REG_4,   BPF_REG_2, (int16_t)      3,        0x0 },
-    { 0x67,   BPF_REG_4,   BPF_REG_0, (int16_t)      0,       0x28 },
-    { 0x4f,   BPF_REG_3,   BPF_REG_4, (int16_t)      0,        0x0 },
-    { 0x71,   BPF_REG_4,   BPF_REG_2, (int16_t)      4,        0x0 },
-    { 0x67,   BPF_REG_4,   BPF_REG_0, (int16_t)      0,       0x20 },
-    { 0x4f,   BPF_REG_3,   BPF_REG_4, (int16_t)      0,        0x0 },
-    { 0x71,   BPF_REG_4,   BPF_REG_2, (int16_t)      5,        0x0 },
-    { 0x67,   BPF_REG_4,   BPF_REG_0, (int16_t)      0,       0x18 },
-    { 0x4f,   BPF_REG_3,   BPF_REG_4, (int16_t)      0,        0x0 },
-    { 0x71,   BPF_REG_4,   BPF_REG_2, (int16_t)      6,        0x0 },
-    { 0x67,   BPF_REG_4,   BPF_REG_0, (int16_t)      0,       0x10 },
-    { 0x4f,   BPF_REG_3,   BPF_REG_4, (int16_t)      0,        0x0 },
-    { 0x71,   BPF_REG_4,   BPF_REG_2, (int16_t)      7,        0x0 },
-    { 0x67,   BPF_REG_4,   BPF_REG_0, (int16_t)      0,        0x8 },
-    { 0x4f,   BPF_REG_3,   BPF_REG_4, (int16_t)      0,        0x0 },
-    { 0x71,   BPF_REG_2,   BPF_REG_2, (int16_t)      8,        0x0 },
-    { 0x4f,   BPF_REG_3,   BPF_REG_2, (int16_t)      0,        0x0 },
-    { 0x7b,  BPF_REG_10,   BPF_REG_3, (int16_t)  65528,        0x0 },
+    { 0xbf,   BPF_REG_6,   BPF_REG_1, (int16_t)      0,        0x0 },
+    { 0x79,   BPF_REG_8,   BPF_REG_6, (int16_t)      8,        0x0 },
+    { 0x79,   BPF_REG_7,   BPF_REG_6, (int16_t)      0,        0x0 },
+    { 0xbf,   BPF_REG_1,   BPF_REG_7, (int16_t)      0,        0x0 },
+    {  0x7,   BPF_REG_1,   BPF_REG_0, (int16_t)      0,        0x8 },
+    { 0x2d,   BPF_REG_8,   BPF_REG_1, (int16_t)     10,        0x0 },
+    { 0xbf,   BPF_REG_3,  BPF_REG_10, (int16_t)      0,        0x0 },
+    {  0x7,   BPF_REG_3,   BPF_REG_0, (int16_t)      0, 0xfffffff7 },
+    { 0xbf,   BPF_REG_1,   BPF_REG_6, (int16_t)      0,        0x0 },
+    { 0xb7,   BPF_REG_2,   BPF_REG_0, (int16_t)      0,        0x8 },
+    { 0xb7,   BPF_REG_4,   BPF_REG_0, (int16_t)      0,        0x1 },
+    { 0x85,   BPF_REG_0,   BPF_REG_0, (int16_t)      0,       0x1a },
+    { 0x15,   BPF_REG_0,   BPF_REG_0, (int16_t)      1,        0x0 },
+    {  0x5,   BPF_REG_0,   BPF_REG_0, (int16_t)     67,        0x0 },
+    { 0x71,   BPF_REG_1,  BPF_REG_10, (int16_t)  65527,        0x0 },
+    {  0x5,   BPF_REG_0,   BPF_REG_0, (int16_t)      2,        0x0 },
+    { 0x71,   BPF_REG_1,   BPF_REG_1, (int16_t)      0,        0x0 },
+    { 0x73,  BPF_REG_10,   BPF_REG_1, (int16_t)  65527,        0x0 },
+    { 0xb7,   BPF_REG_2,   BPF_REG_0, (int16_t)      0,        0x9 },
+    { 0x67,   BPF_REG_1,   BPF_REG_0, (int16_t)      0,       0x38 },
+    { 0xc7,   BPF_REG_1,   BPF_REG_0, (int16_t)      0,       0x38 },
+    { 0x65,   BPF_REG_1,   BPF_REG_0, (int16_t)     18, 0xffffffff },
+    { 0xbf,   BPF_REG_1,   BPF_REG_7, (int16_t)      0,        0x0 },
+    {  0x7,   BPF_REG_1,   BPF_REG_0, (int16_t)      0,        0xd },
+    { 0x2d,   BPF_REG_8,   BPF_REG_1, (int16_t)     11,        0x0 },
+    { 0xbf,   BPF_REG_3,  BPF_REG_10, (int16_t)      0,        0x0 },
+    {  0x7,   BPF_REG_3,   BPF_REG_0, (int16_t)      0, 0xfffffff7 },
+    { 0xbf,   BPF_REG_1,   BPF_REG_6, (int16_t)      0,        0x0 },
+    { 0xb7,   BPF_REG_2,   BPF_REG_0, (int16_t)      0,        0xd },
+    { 0xb7,   BPF_REG_4,   BPF_REG_0, (int16_t)      0,        0x1 },
+    { 0x85,   BPF_REG_0,   BPF_REG_0, (int16_t)      0,       0x1a },
+    { 0x55,   BPF_REG_0,   BPF_REG_0, (int16_t)     49,        0x0 },
+    { 0xb7,   BPF_REG_2,   BPF_REG_0, (int16_t)      0,        0xe },
+    { 0x71,   BPF_REG_1,  BPF_REG_10, (int16_t)  65527,        0x0 },
+    { 0x15,   BPF_REG_1,   BPF_REG_0, (int16_t)      5,       0x14 },
+    {  0x5,   BPF_REG_0,   BPF_REG_0, (int16_t)     45,        0x0 },
+    { 0xb7,   BPF_REG_2,   BPF_REG_0, (int16_t)      0,        0xe },
+    { 0x71,   BPF_REG_1,   BPF_REG_1, (int16_t)      0,        0x0 },
+    { 0x73,  BPF_REG_10,   BPF_REG_1, (int16_t)  65527,        0x0 },
+    { 0x55,   BPF_REG_1,   BPF_REG_0, (int16_t)     41,       0x14 },
+    {  0xf,   BPF_REG_7,   BPF_REG_2, (int16_t)      0,        0x0 },
+    { 0xbf,   BPF_REG_1,   BPF_REG_7, (int16_t)      0,        0x0 },
+    {  0x7,   BPF_REG_1,   BPF_REG_0, (int16_t)      0,       0x14 },
+    { 0x3d,   BPF_REG_8,   BPF_REG_1, (int16_t)      7,        0x0 },
+    { 0xbf,   BPF_REG_7,  BPF_REG_10, (int16_t)      0,        0x0 },
+    {  0x7,   BPF_REG_7,   BPF_REG_0, (int16_t)      0, 0xffffffe3 },
+    { 0xbf,   BPF_REG_1,   BPF_REG_6, (int16_t)      0,        0x0 },
+    { 0xbf,   BPF_REG_3,   BPF_REG_7, (int16_t)      0,        0x0 },
+    { 0xb7,   BPF_REG_4,   BPF_REG_0, (int16_t)      0,       0x14 },
+    { 0x85,   BPF_REG_0,   BPF_REG_0, (int16_t)      0,       0x1a },
+    { 0x55,   BPF_REG_0,   BPF_REG_0, (int16_t)     30,        0x0 },
+    { 0x71,   BPF_REG_2,   BPF_REG_7, (int16_t)      0,        0x0 },
+    { 0x67,   BPF_REG_2,   BPF_REG_0, (int16_t)      0,       0x38 },
+    { 0x71,   BPF_REG_1,   BPF_REG_7, (int16_t)      1,        0x0 },
+    { 0x67,   BPF_REG_1,   BPF_REG_0, (int16_t)      0,       0x30 },
+    { 0x4f,   BPF_REG_1,   BPF_REG_2, (int16_t)      0,        0x0 },
+    { 0x71,   BPF_REG_2,   BPF_REG_7, (int16_t)      2,        0x0 },
+    { 0x67,   BPF_REG_2,   BPF_REG_0, (int16_t)      0,       0x28 },
+    { 0x4f,   BPF_REG_1,   BPF_REG_2, (int16_t)      0,        0x0 },
+    { 0x71,   BPF_REG_2,   BPF_REG_7, (int16_t)      3,        0x0 },
+    { 0x67,   BPF_REG_2,   BPF_REG_0, (int16_t)      0,       0x20 },
+    { 0x4f,   BPF_REG_1,   BPF_REG_2, (int16_t)      0,        0x0 },
+    { 0x71,   BPF_REG_2,   BPF_REG_7, (int16_t)      4,        0x0 },
+    { 0x67,   BPF_REG_2,   BPF_REG_0, (int16_t)      0,       0x18 },
+    { 0x4f,   BPF_REG_1,   BPF_REG_2, (int16_t)      0,        0x0 },
+    { 0x71,   BPF_REG_2,   BPF_REG_7, (int16_t)      5,        0x0 },
+    { 0x67,   BPF_REG_2,   BPF_REG_0, (int16_t)      0,       0x10 },
+    { 0x4f,   BPF_REG_1,   BPF_REG_2, (int16_t)      0,        0x0 },
+    { 0x71,   BPF_REG_2,   BPF_REG_7, (int16_t)      6,        0x0 },
+    { 0x67,   BPF_REG_2,   BPF_REG_0, (int16_t)      0,        0x8 },
+    { 0x4f,   BPF_REG_1,   BPF_REG_2, (int16_t)      0,        0x0 },
+    { 0x71,   BPF_REG_2,   BPF_REG_7, (int16_t)      7,        0x0 },
+    { 0x4f,   BPF_REG_1,   BPF_REG_2, (int16_t)      0,        0x0 },
+    { 0x7b,  BPF_REG_10,   BPF_REG_1, (int16_t)  65528,        0x0 },
     { 0xbf,   BPF_REG_3,  BPF_REG_10, (int16_t)      0,        0x0 },
     {  0x7,   BPF_REG_3,   BPF_REG_0, (int16_t)      0, 0xfffffff8 },
+    { 0xbf,   BPF_REG_1,   BPF_REG_6, (int16_t)      0,        0x0 },
     { 0x18,   BPF_REG_2,   BPF_REG_0, (int16_t)      0,        0x0 },
     {  0x0,   BPF_REG_0,   BPF_REG_0, (int16_t)      0,        0x0 },
     { 0xb7,   BPF_REG_4,   BPF_REG_0, (int16_t)      0,        0x0 },