dynptr for skb metadata behaves the same way as the dynptr for skb data with one exception - writes to skb_meta dynptr don't invalidate existing skb and skb_meta slices. Duplicate those the skb dynptr tests which we can, since bpf_dynptr_from_skb_meta kfunc can be called only from TC BPF, to cover the skb_meta dynptr verifier checks. Also add a couple of new tests (skb_data_valid_*) to ensure we don't invalidate the slices in the mentioned case, which are specific to skb_meta dynptr. Reviewed-by: Jesse Brandeburg Signed-off-by: Jakub Sitnicki --- tools/testing/selftests/bpf/prog_tests/dynptr.c | 2 + tools/testing/selftests/bpf/progs/dynptr_fail.c | 258 +++++++++++++++++++++ tools/testing/selftests/bpf/progs/dynptr_success.c | 55 +++++ 3 files changed, 315 insertions(+) diff --git a/tools/testing/selftests/bpf/prog_tests/dynptr.c b/tools/testing/selftests/bpf/prog_tests/dynptr.c index 9b2d9ceda210..b9f86cb91e81 100644 --- a/tools/testing/selftests/bpf/prog_tests/dynptr.c +++ b/tools/testing/selftests/bpf/prog_tests/dynptr.c @@ -32,6 +32,8 @@ static struct { {"test_ringbuf", SETUP_SYSCALL_SLEEP}, {"test_skb_readonly", SETUP_SKB_PROG}, {"test_dynptr_skb_data", SETUP_SKB_PROG}, + {"test_dynptr_skb_meta_data", SETUP_SKB_PROG}, + {"test_dynptr_skb_meta_flags", SETUP_SKB_PROG}, {"test_adjust", SETUP_SYSCALL_SLEEP}, {"test_adjust_err", SETUP_SYSCALL_SLEEP}, {"test_zero_size_dynptr", SETUP_SYSCALL_SLEEP}, diff --git a/tools/testing/selftests/bpf/progs/dynptr_fail.c b/tools/testing/selftests/bpf/progs/dynptr_fail.c index bd8f15229f5c..dda6a8dada82 100644 --- a/tools/testing/selftests/bpf/progs/dynptr_fail.c +++ b/tools/testing/selftests/bpf/progs/dynptr_fail.c @@ -269,6 +269,26 @@ int data_slice_out_of_bounds_skb(struct __sk_buff *skb) return SK_PASS; } +/* A metadata slice can't be accessed out of bounds */ +SEC("?tc") +__failure __msg("value is outside of the allowed memory range") +int data_slice_out_of_bounds_skb_meta(struct __sk_buff *skb) +{ + struct bpf_dynptr meta; + __u8 *md; + + bpf_dynptr_from_skb_meta(skb, 0, &meta); + + md = bpf_dynptr_slice_rdwr(&meta, 0, NULL, sizeof(*md)); + if (!md) + return SK_DROP; + + /* this should fail */ + *(md + 1) = 42; + + return SK_PASS; +} + SEC("?raw_tp") __failure __msg("value is outside of the allowed memory range") int data_slice_out_of_bounds_map_value(void *ctx) @@ -1089,6 +1109,26 @@ int skb_invalid_slice_write(struct __sk_buff *skb) return SK_PASS; } +/* bpf_dynptr_slice()s are read-only and cannot be written to */ +SEC("?tc") +__failure __msg("R{{[0-9]+}} cannot write into rdonly_mem") +int skb_meta_invalid_slice_write(struct __sk_buff *skb) +{ + struct bpf_dynptr meta; + __u8 *md; + + bpf_dynptr_from_skb_meta(skb, 0, &meta); + + md = bpf_dynptr_slice(&meta, 0, NULL, sizeof(*md)); + if (!md) + return SK_DROP; + + /* this should fail */ + *md = 42; + + return SK_PASS; +} + /* The read-only data slice is invalidated whenever a helper changes packet data */ SEC("?tc") __failure __msg("invalid mem access 'scalar'") @@ -1192,6 +1232,188 @@ int skb_invalid_data_slice4(struct __sk_buff *skb) return SK_PASS; } +/* Read-only skb data slice is invalidated on write to skb metadata */ +SEC("?tc") +__failure __msg("invalid mem access 'scalar'") +int ro_skb_slice_invalid_after_metadata_write(struct __sk_buff *skb) +{ + struct bpf_dynptr data, meta; + __u8 *d; + + bpf_dynptr_from_skb(skb, 0, &data); + bpf_dynptr_from_skb_meta(skb, 0, &meta); + + d = bpf_dynptr_slice(&data, 0, NULL, sizeof(*d)); + if (!d) + return SK_DROP; + + bpf_dynptr_write(&meta, 0, "x", 1, 0); + + /* this should fail */ + val = *d; + + return SK_PASS; +} + +/* Read-write skb data slice is invalidated on write to skb metadata */ +SEC("?tc") +__failure __msg("invalid mem access 'scalar'") +int rw_skb_slice_invalid_after_metadata_write(struct __sk_buff *skb) +{ + struct bpf_dynptr data, meta; + __u8 *d; + + bpf_dynptr_from_skb(skb, 0, &data); + bpf_dynptr_from_skb_meta(skb, 0, &meta); + + d = bpf_dynptr_slice_rdwr(&data, 0, NULL, sizeof(*d)); + if (!d) + return SK_DROP; + + bpf_dynptr_write(&meta, 0, "x", 1, 0); + + /* this should fail */ + *d = 42; + + return SK_PASS; +} + +/* Read-only skb metadata slice is invalidated on write to skb data */ +SEC("?tc") +__failure __msg("invalid mem access 'scalar'") +int ro_skb_meta_slice_invalid_after_payload_write(struct __sk_buff *skb) +{ + struct bpf_dynptr data, meta; + __u8 *md; + + bpf_dynptr_from_skb(skb, 0, &data); + bpf_dynptr_from_skb_meta(skb, 0, &meta); + + md = bpf_dynptr_slice(&meta, 0, NULL, sizeof(*md)); + if (!md) + return SK_DROP; + + bpf_dynptr_write(&data, 0, "x", 1, 0); + + /* this should fail */ + val = *md; + + return SK_PASS; +} + +/* Read-write skb metadata slice is invalidated on write to skb data slice */ +SEC("?tc") +__failure __msg("invalid mem access 'scalar'") +int rw_skb_meta_slice_invalid_after_payload_write(struct __sk_buff *skb) +{ + struct bpf_dynptr data, meta; + __u8 *md; + + bpf_dynptr_from_skb(skb, 0, &data); + bpf_dynptr_from_skb_meta(skb, 0, &meta); + + md = bpf_dynptr_slice_rdwr(&meta, 0, NULL, sizeof(*md)); + if (!md) + return SK_DROP; + + bpf_dynptr_write(&data, 0, "x", 1, 0); + + /* this should fail */ + *md = 42; + + return SK_PASS; +} + +/* Read-only skb metadata slice is invalidated whenever a helper changes packet data */ +SEC("?tc") +__failure __msg("invalid mem access 'scalar'") +int ro_skb_meta_slice_invalid_after_payload_helper(struct __sk_buff *skb) +{ + struct bpf_dynptr meta; + __u8 *md; + + bpf_dynptr_from_skb_meta(skb, 0, &meta); + + md = bpf_dynptr_slice(&meta, 0, NULL, sizeof(*md)); + if (!md) + return SK_DROP; + + if (bpf_skb_pull_data(skb, skb->len)) + return SK_DROP; + + /* this should fail */ + val = *md; + + return SK_PASS; +} + +/* Read-write skb metadata slice is invalidated whenever a helper changes packet data */ +SEC("?tc") +__failure __msg("invalid mem access 'scalar'") +int rw_skb_meta_slice_invalid_after_payload_helper(struct __sk_buff *skb) +{ + struct bpf_dynptr meta; + __u8 *md; + + bpf_dynptr_from_skb_meta(skb, 0, &meta); + + md = bpf_dynptr_slice_rdwr(&meta, 0, NULL, sizeof(*md)); + if (!md) + return SK_DROP; + + if (bpf_skb_pull_data(skb, skb->len)) + return SK_DROP; + + /* this should fail */ + *md = 42; + + return SK_PASS; +} + +/* Read-only skb metadata slice is invalidated on write to skb metadata */ +SEC("?tc") +__failure __msg("invalid mem access 'scalar'") +int ro_skb_meta_slice_invalid_after_metadata_write(struct __sk_buff *skb) +{ + struct bpf_dynptr meta; + __u8 *md; + + bpf_dynptr_from_skb_meta(skb, 0, &meta); + + md = bpf_dynptr_slice(&meta, 0, NULL, sizeof(*md)); + if (!md) + return SK_DROP; + + bpf_dynptr_write(&meta, 0, "x", 1, 0); + + /* this should fail */ + val = *md; + + return SK_PASS; +} + +/* Read-write skb metadata slice is invalidated on write to skb metadata */ +SEC("?tc") +__failure __msg("invalid mem access 'scalar'") +int rw_skb_meta_slice_invalid_after_metadata_write(struct __sk_buff *skb) +{ + struct bpf_dynptr meta; + __u8 *md; + + bpf_dynptr_from_skb_meta(skb, 0, &meta); + + md = bpf_dynptr_slice_rdwr(&meta, 0, NULL, sizeof(*md)); + if (!md) + return SK_DROP; + + bpf_dynptr_write(&meta, 0, "x", 1, 0); + + /* this should fail */ + *md = 42; + + return SK_PASS; +} + /* The read-only data slice is invalidated whenever a helper changes packet data */ SEC("?xdp") __failure __msg("invalid mem access 'scalar'") @@ -1255,6 +1477,19 @@ int skb_invalid_ctx(void *ctx) return 0; } +/* Only supported prog type can create skb_meta-type dynptrs */ +SEC("?raw_tp") +__failure __msg("calling kernel function bpf_dynptr_from_skb_meta is not allowed") +int skb_meta_invalid_ctx(void *ctx) +{ + struct bpf_dynptr meta; + + /* this should fail */ + bpf_dynptr_from_skb_meta(ctx, 0, &meta); + + return 0; +} + SEC("fentry/skb_tx_error") __failure __msg("must be referenced or trusted") int BPF_PROG(skb_invalid_ctx_fentry, void *skb) @@ -1665,6 +1900,29 @@ int clone_skb_packet_data(struct __sk_buff *skb) return 0; } +/* A skb clone's metadata slice becomes invalid anytime packet data changes */ +SEC("?tc") +__failure __msg("invalid mem access 'scalar'") +int clone_skb_packet_meta(struct __sk_buff *skb) +{ + struct bpf_dynptr clone, meta; + __u8 *md; + + bpf_dynptr_from_skb_meta(skb, 0, &meta); + bpf_dynptr_clone(&meta, &clone); + md = bpf_dynptr_slice_rdwr(&clone, 0, NULL, sizeof(*md)); + if (!md) + return SK_DROP; + + if (bpf_skb_pull_data(skb, skb->len)) + return SK_DROP; + + /* this should fail */ + *md = 42; + + return 0; +} + /* A xdp clone's data slices should be invalid anytime packet data changes */ SEC("?xdp") __failure __msg("invalid mem access 'scalar'") diff --git a/tools/testing/selftests/bpf/progs/dynptr_success.c b/tools/testing/selftests/bpf/progs/dynptr_success.c index 8315273cb900..127dea342e5a 100644 --- a/tools/testing/selftests/bpf/progs/dynptr_success.c +++ b/tools/testing/selftests/bpf/progs/dynptr_success.c @@ -211,6 +211,61 @@ int test_dynptr_skb_data(struct __sk_buff *skb) return 1; } +SEC("?tc") +int test_dynptr_skb_meta_data(struct __sk_buff *skb) +{ + struct bpf_dynptr meta; + __u8 *md; + int ret; + + err = 1; + ret = bpf_dynptr_from_skb_meta(skb, 0, &meta); + if (ret) + return 1; + + /* This should return NULL. Must use bpf_dynptr_slice API */ + err = 2; + md = bpf_dynptr_data(&meta, 0, sizeof(*md)); + if (md) + return 1; + + err = 0; + return 1; +} + +/* Check that skb metadata dynptr ops don't accept any flags. */ +SEC("?tc") +int test_dynptr_skb_meta_flags(struct __sk_buff *skb) +{ + const __u64 INVALID_FLAGS = ~0ULL; + struct bpf_dynptr meta; + __u8 buf; + int ret; + + err = 1; + ret = bpf_dynptr_from_skb_meta(skb, INVALID_FLAGS, &meta); + if (ret != -EINVAL) + return 1; + + err = 2; + ret = bpf_dynptr_from_skb_meta(skb, 0, &meta); + if (ret) + return 1; + + err = 3; + ret = bpf_dynptr_read(&buf, 0, &meta, 0, INVALID_FLAGS); + if (ret != -EINVAL) + return 1; + + err = 4; + ret = bpf_dynptr_write(&meta, 0, &buf, 0, INVALID_FLAGS); + if (ret != -EINVAL) + return 1; + + err = 0; + return 1; +} + SEC("tp/syscalls/sys_enter_nanosleep") int test_adjust(void *ctx) { -- 2.43.0