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Exercise this with bpf_skb_ct_lookup(), which writes errors through its opts memory argument. Verify that the verifier marks the program as directly writing packet data, causing TC to emit its writable-skb prologue. Match the semantic prologue sequence while allowing architecture-specific zero extensions and the endian-specific cloned-bit mask. Signed-off-by: Amery Hung --- .../selftests/bpf/prog_tests/verifier.c | 2 + .../bpf/progs/verifier_kfunc_packet_access.c | 47 +++++++++++++++++++ 2 files changed, 49 insertions(+) create mode 100644 tools/testing/selftests/bpf/progs/verifier_kfunc_packet_access.c diff --git a/tools/testing/selftests/bpf/prog_tests/verifier.c b/tools/testing/selftests/bpf/prog_tests/verifier.c index f7f94ccebce2..b97381448248 100644 --- a/tools/testing/selftests/bpf/prog_tests/verifier.c +++ b/tools/testing/selftests/bpf/prog_tests/verifier.c @@ -54,6 +54,7 @@ #include "verifier_iterating_callbacks.skel.h" #include "verifier_jeq_infer_not_null.skel.h" #include "verifier_jit_convergence.skel.h" +#include "verifier_kfunc_packet_access.skel.h" #include "verifier_ld_ind.skel.h" #include "verifier_ldsx.skel.h" #include "verifier_leak_ptr.skel.h" @@ -218,6 +219,7 @@ void test_verifier_int_ptr(void) { RUN(verifier_int_ptr); } void test_verifier_iterating_callbacks(void) { RUN(verifier_iterating_callbacks); } void test_verifier_jeq_infer_not_null(void) { RUN(verifier_jeq_infer_not_null); } void test_verifier_jit_convergence(void) { RUN(verifier_jit_convergence); } +void test_verifier_kfunc_packet_access(void) { RUN_TESTS(verifier_kfunc_packet_access); } void test_verifier_load_acquire(void) { RUN(verifier_load_acquire); } void test_verifier_ld_ind(void) { RUN(verifier_ld_ind); } void test_verifier_ldsx(void) { RUN(verifier_ldsx); } diff --git a/tools/testing/selftests/bpf/progs/verifier_kfunc_packet_access.c b/tools/testing/selftests/bpf/progs/verifier_kfunc_packet_access.c new file mode 100644 index 000000000000..9ae63c9eab02 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/verifier_kfunc_packet_access.c @@ -0,0 +1,47 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include +#include +#include "bpf_misc.h" + +struct nf_conn *bpf_skb_ct_lookup(struct __sk_buff *skb_ctx, + struct bpf_sock_tuple *bpf_tuple, + u32 tuple__sz, struct bpf_ct_opts *opts, + u32 opts__sz) __ksym; +void bpf_ct_release(struct nf_conn *nfct) __ksym; + +char _license[] SEC("license") = "GPL"; + +SEC("tc") +__description("kfunc packet write requests writable skb") +__success +/* bpf_unclone_prologue() */ +__xlated("r6 = *(u8 *)(r1 +{{[0-9]+}})") +__xlated("...") +__xlated("w6 &= {{1|128}}") +__xlated("...") +__xlated("if r6 == 0x0 goto") +__xlated("r6 = r1") +__xlated("r2 ^= r2") +__xlated("call") +__xlated("if r0 == 0x0 goto") +__xlated("w0 = 2") +__xlated("...") +__xlated("exit") +__xlated("r1 = r6") +int kfunc_packet_write(struct __sk_buff *skb) +{ + void *data_end = (void *)(long)skb->data_end; + void *data = (void *)(long)skb->data; + struct bpf_sock_tuple tuple = {}; + struct nf_conn *nfct; + + if (data + sizeof(struct bpf_ct_opts) > data_end) + return 0; + + /* An invalid tuple size makes bpf_skb_ct_lookup() write opts->error. */ + nfct = bpf_skb_ct_lookup(skb, &tuple, 1, data, sizeof(struct bpf_ct_opts)); + if (nfct) + bpf_ct_release(nfct); + return 0; +} -- 2.52.0