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bpf,test: Fix verifier issues in IPv6 BPF tests when running locally #25191

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merged 1 commit into from
May 1, 2023
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bpf,test: Fix verifier issues in IPv6 BPF tests when running locally #25191

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3 changes: 3 additions & 0 deletions bpf/tests/ipv6_test.c
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Original file line number Diff line number Diff line change
Expand Up @@ -144,6 +144,9 @@ int ipv6_with_hop_auth_tcp_pktgen(struct __ctx_buff *ctx)
return TEST_ERROR;

authhdr = (struct ipv6_authhdr *)l3_next;
if ((void *) authhdr + sizeof(struct ipv6_authhdr) > ctx_data_end(ctx))
return TEST_ERROR;

authhdr->spi = 0x222;
authhdr->seq = 1;

Expand Down
41 changes: 7 additions & 34 deletions bpf/tests/pktgen.h
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Original file line number Diff line number Diff line change
Expand Up @@ -147,8 +147,8 @@ enum pkt_layer {
/* Packet builder */
struct pktgen {
struct __ctx_buff *ctx;
__u16 cur_off;
__u16 layer_offsets[PKT_BUILDER_LAYERS];
__u64 cur_off;
__u64 layer_offsets[PKT_BUILDER_LAYERS];
enum pkt_layer layers[PKT_BUILDER_LAYERS];
};

Expand Down Expand Up @@ -176,29 +176,6 @@ int pktgen__free_layer(const struct pktgen *builder)
return -1;
}

static __always_inline
__attribute__((warn_unused_result))
int ctx_data_valid(const struct __ctx_buff *ctx, __maybe_unused __u16 off)
{
int ret = 0;

/* try to open up a range on the pkt reg */
asm volatile("r1 = *(u32 *)(%[ctx] +0)\n\t"
"r2 = *(u32 *)(%[ctx] +4)\n\t"
"%[off] &= %[offmax]\n\t"
"r1 += %[off]\n\t"
"if r1 > r2 goto +2\n\t"
"%[ret] = 0\n\t"
"goto +1\n\t"
"%[ret] = %[errno]\n\t"
: [ret]"=r"(ret)
: [ctx]"r"(ctx), [off]"r"(off),
[offmax]"i"(0xff), [errno]"i"(-EINVAL)
: "r1", "r2");

return ret;
}

/* Push an empty ethernet header onto the packet */
static __always_inline
__attribute__((warn_unused_result))
Expand Down Expand Up @@ -398,11 +375,7 @@ struct ipv6_opt_hdr *pktgen__append_ipv6_extension_header(struct pktgen *builder
if (!hdr)
return NULL;

/* after multiple extension headers are added, LLVM tends to generate
* code that verifier doesn't understand. try to open up a range on
* the pkt reg
*/
if (ctx_data_valid(builder->ctx, builder->cur_off))
if ((void *) hdr + sizeof(struct ipv6_opt_hdr) > ctx_data_end(builder->ctx))
return NULL;

hdr->hdrlen = hdrlen;
Expand Down Expand Up @@ -537,7 +510,7 @@ void *pktgen__push_data_room(struct pktgen *builder, int len)
/* Check that any value within the struct will not exceed a u16 which
* is the max allowed offset within a packet from ctx->data.
*/
if (builder->cur_off >= MAX_PACKET_OFF - len)
if ((__s64)builder->cur_off >= MAX_PACKET_OFF - len)
return 0;

layer = ctx_data(ctx) + builder->cur_off;
Expand Down Expand Up @@ -581,10 +554,10 @@ void pktgen__finish(const struct pktgen *builder)
struct ipv6hdr *ipv6_layer;
struct ipv6_opt_hdr *ipv6_opt_layer;
struct tcphdr *tcp_layer;
__u16 layer_off;
__u64 layer_off;
__u16 v4len;
__be16 v6len;
__u16 hdr_size;
__u64 hdr_size;

#pragma unroll
for (int i = 0; i < PKT_BUILDER_LAYERS; i++) {
Expand Down Expand Up @@ -780,7 +753,7 @@ void pktgen__finish(const struct pktgen *builder)
builder->layer_offsets[i];
}

tcp_layer->doff = hdr_size / 4;
tcp_layer->doff = (__u16)hdr_size / 4;

break;

Expand Down