Add inline-asm based verifier tests that exercise stack argument validation logic directly. Positive tests: - subprog call with 6 arg's - Two sequential calls to different subprogs (6-arg and 7-arg) - Share a r11 store for both branches Negative tests — verifier rejection: - Read from uninitialized incoming stack arg slot - Gap in outgoing slots: only r11-16 written, r11-8 missing - Write at r11-80, exceeding max 7 stack args - Missing store on one branch with a shared store - First call has proper stack arguments and the second call intends to inherit stack arguments but not working - r11 load ordering issue Negative tests — pointer/ref tracking: - Pruning type mismatch: one branch stores PTR_TO_STACK, the other stores a scalar, callee dereferences — must not prune - Release invalidation: bpf_sk_release invalidates a socket pointer stored in a stack arg slot - Packet pointer invalidation: bpf_skb_pull_data invalidates a packet pointer stored in a stack arg slot - Null propagation: PTR_TO_MAP_VALUE_OR_NULL stored in stack arg slot, null branch attempts dereference via callee Signed-off-by: Yonghong Song --- .../selftests/bpf/prog_tests/verifier.c | 4 + .../bpf/progs/btf__verifier_stack_arg_order.c | 40 ++ .../selftests/bpf/progs/verifier_stack_arg.c | 444 ++++++++++++++++++ .../bpf/progs/verifier_stack_arg_order.c | 126 +++++ 4 files changed, 614 insertions(+) create mode 100644 tools/testing/selftests/bpf/progs/btf__verifier_stack_arg_order.c create mode 100644 tools/testing/selftests/bpf/progs/verifier_stack_arg.c create mode 100644 tools/testing/selftests/bpf/progs/verifier_stack_arg_order.c diff --git a/tools/testing/selftests/bpf/prog_tests/verifier.c b/tools/testing/selftests/bpf/prog_tests/verifier.c index a96b25ebff23..ee3d929fac8a 100644 --- a/tools/testing/selftests/bpf/prog_tests/verifier.c +++ b/tools/testing/selftests/bpf/prog_tests/verifier.c @@ -91,6 +91,8 @@ #include "verifier_sockmap_mutate.skel.h" #include "verifier_spill_fill.skel.h" #include "verifier_spin_lock.skel.h" +#include "verifier_stack_arg.skel.h" +#include "verifier_stack_arg_order.skel.h" #include "verifier_stack_ptr.skel.h" #include "verifier_store_release.skel.h" #include "verifier_subprog_precision.skel.h" @@ -238,6 +240,8 @@ void test_verifier_sock_addr(void) { RUN(verifier_sock_addr); } void test_verifier_sockmap_mutate(void) { RUN(verifier_sockmap_mutate); } void test_verifier_spill_fill(void) { RUN(verifier_spill_fill); } void test_verifier_spin_lock(void) { RUN(verifier_spin_lock); } +void test_verifier_stack_arg(void) { RUN(verifier_stack_arg); } +void test_verifier_stack_arg_order(void) { RUN(verifier_stack_arg_order); } void test_verifier_stack_ptr(void) { RUN(verifier_stack_ptr); } void test_verifier_store_release(void) { RUN(verifier_store_release); } void test_verifier_subprog_precision(void) { RUN(verifier_subprog_precision); } diff --git a/tools/testing/selftests/bpf/progs/btf__verifier_stack_arg_order.c b/tools/testing/selftests/bpf/progs/btf__verifier_stack_arg_order.c new file mode 100644 index 000000000000..83692570d5bc --- /dev/null +++ b/tools/testing/selftests/bpf/progs/btf__verifier_stack_arg_order.c @@ -0,0 +1,40 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */ +#include +#include + +#if defined(__TARGET_ARCH_x86) && defined(__BPF_FEATURE_STACK_ARGUMENT) + +int subprog_bad_order_6args(int a, int b, int c, int d, int e, int f) +{ + return a + b + c + d + e + f; +} + +int subprog_call_before_load_6args(int a, int b, int c, int d, int e, int f) +{ + return a + b + c + d + e + f; +} + +int subprog_pruning_call_before_load_6args(int a, int b, int c, int d, int e, int f) +{ + return a + b + c + d + e + f; +} + +#else + +int subprog_bad_order_6args(void) +{ + return 0; +} + +int subprog_call_before_load_6args(void) +{ + return 0; +} + +int subprog_pruning_call_before_load_6args(void) +{ + return 0; +} + +#endif diff --git a/tools/testing/selftests/bpf/progs/verifier_stack_arg.c b/tools/testing/selftests/bpf/progs/verifier_stack_arg.c new file mode 100644 index 000000000000..6587bf912bc0 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/verifier_stack_arg.c @@ -0,0 +1,444 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */ + +#include +#include +#include "bpf_misc.h" + +struct { + __uint(type, BPF_MAP_TYPE_HASH); + __uint(max_entries, 1); + __type(key, long long); + __type(value, long long); +} map_hash_8b SEC(".maps"); + +#if defined(__TARGET_ARCH_x86) && defined(__BPF_FEATURE_STACK_ARGUMENT) + +__noinline __used +static int subprog_6args(int a, int b, int c, int d, int e, int f) +{ + return a + b + c + d + e + f; +} + +__noinline __used +static int subprog_7args(int a, int b, int c, int d, int e, int f, int g) +{ + return a + b + c + d + e + f + g; +} + +__noinline __used +static long subprog_deref_arg6(long a, long b, long c, long d, long e, long *f) +{ + return *f; +} + +SEC("tc") +__description("stack_arg: subprog with 6 args") +__success __retval(21) +__naked void stack_arg_6args(void) +{ + asm volatile ( + "r1 = 1;" + "r2 = 2;" + "r3 = 3;" + "r4 = 4;" + "r5 = 5;" + "*(u64 *)(r11 - 8) = 6;" + "call subprog_6args;" + "exit;" + ::: __clobber_all + ); +} + +SEC("tc") +__description("stack_arg: two subprogs with >5 args") +__success __retval(90) +__naked void stack_arg_two_subprogs(void) +{ + asm volatile ( + "r1 = 1;" + "r2 = 2;" + "r3 = 3;" + "r4 = 4;" + "r5 = 5;" + "*(u64 *)(r11 - 8) = 10;" + "call subprog_6args;" + "r6 = r0;" + "r1 = 1;" + "r2 = 2;" + "r3 = 3;" + "r4 = 4;" + "r5 = 5;" + "*(u64 *)(r11 - 16) = 30;" + "*(u64 *)(r11 - 8) = 20;" + "call subprog_7args;" + "r0 += r6;" + "exit;" + ::: __clobber_all + ); +} + +SEC("tc") +__description("stack_arg: read from uninitialized stack arg slot") +__failure +__msg("invalid read from stack arg off 8 depth 0") +__naked void stack_arg_read_uninitialized(void) +{ + asm volatile ( + "r0 = *(u64 *)(r11 + 8);" + "r0 = 0;" + "exit;" + ::: __clobber_all + ); +} + +SEC("tc") +__description("stack_arg: gap at offset -8, only wrote -16") +__failure +__msg("callee expects 7 args, stack arg1 is not initialized") +__naked void stack_arg_gap_at_minus8(void) +{ + asm volatile ( + "r1 = 1;" + "r2 = 2;" + "r3 = 3;" + "r4 = 4;" + "r5 = 5;" + "*(u64 *)(r11 - 16) = 30;" + "call subprog_7args;" + "exit;" + ::: __clobber_all + ); +} + +SEC("tc") +__description("stack_arg: pruning with different stack arg types") +__failure +__flag(BPF_F_TEST_STATE_FREQ) +__msg("R{{[0-9]}} invalid mem access 'scalar'") +__naked void stack_arg_pruning_type_mismatch(void) +{ + asm volatile ( + "call %[bpf_get_prandom_u32];" + "r6 = r0;" + /* local = 0 on program stack */ + "r7 = 0;" + "*(u64 *)(r10 - 8) = r7;" + /* Branch based on random value */ + "if r6 s> 3 goto l0_%=;" + /* Path 1: store stack pointer to outgoing arg6 */ + "r1 = r10;" + "r1 += -8;" + "*(u64 *)(r11 - 8) = r1;" + "goto l1_%=;" + "l0_%=:" + /* Path 2: store scalar to outgoing arg6 */ + "*(u64 *)(r11 - 8) = 42;" + "l1_%=:" + /* Call subprog that dereferences arg6 */ + "r1 = r6;" + "r2 = 0;" + "r3 = 0;" + "r4 = 0;" + "r5 = 0;" + "call subprog_deref_arg6;" + "exit;" + :: __imm(bpf_get_prandom_u32) + : __clobber_all + ); +} + +SEC("tc") +__description("stack_arg: release_reference invalidates stack arg slot") +__failure +__msg("R{{[0-9]}} !read_ok") +__naked void stack_arg_release_ref(void) +{ + asm volatile ( + "r6 = r1;" + /* struct bpf_sock_tuple tuple = {} */ + "r2 = 0;" + "*(u32 *)(r10 - 8) = r2;" + "*(u64 *)(r10 - 16) = r2;" + "*(u64 *)(r10 - 24) = r2;" + "*(u64 *)(r10 - 32) = r2;" + "*(u64 *)(r10 - 40) = r2;" + "*(u64 *)(r10 - 48) = r2;" + /* sk = bpf_sk_lookup_tcp(ctx, &tuple, sizeof(tuple), 0, 0) */ + "r1 = r6;" + "r2 = r10;" + "r2 += -48;" + "r3 = %[sizeof_bpf_sock_tuple];" + "r4 = 0;" + "r5 = 0;" + "call %[bpf_sk_lookup_tcp];" + /* r0 = sk (PTR_TO_SOCK_OR_NULL) */ + "if r0 == 0 goto l0_%=;" + /* Store sock ref to outgoing arg6 slot */ + "*(u64 *)(r11 - 8) = r0;" + /* Release the reference — invalidates the stack arg slot */ + "r1 = r0;" + "call %[bpf_sk_release];" + /* Call subprog that dereferences arg6 — should fail */ + "r1 = 1;" + "r2 = 2;" + "r3 = 3;" + "r4 = 4;" + "r5 = 5;" + "call subprog_deref_arg6;" + "l0_%=:" + "r0 = 0;" + "exit;" + : + : __imm(bpf_sk_lookup_tcp), + __imm(bpf_sk_release), + __imm_const(sizeof_bpf_sock_tuple, sizeof(struct bpf_sock_tuple)) + : __clobber_all + ); +} + +SEC("tc") +__description("stack_arg: pkt pointer in stack arg slot invalidated after pull_data") +__failure +__msg("R{{[0-9]}} !read_ok") +__naked void stack_arg_stale_pkt_ptr(void) +{ + asm volatile ( + "r6 = r1;" + "r7 = *(u32 *)(r6 + %[__sk_buff_data]);" + "r8 = *(u32 *)(r6 + %[__sk_buff_data_end]);" + /* check pkt has at least 1 byte */ + "r0 = r7;" + "r0 += 8;" + "if r0 > r8 goto l0_%=;" + /* Store valid pkt pointer to outgoing arg6 slot */ + "*(u64 *)(r11 - 8) = r7;" + /* bpf_skb_pull_data invalidates all pkt pointers */ + "r1 = r6;" + "r2 = 0;" + "call %[bpf_skb_pull_data];" + /* Call subprog that dereferences arg6 — should fail */ + "r1 = 1;" + "r2 = 2;" + "r3 = 3;" + "r4 = 4;" + "r5 = 5;" + "call subprog_deref_arg6;" + "l0_%=:" + "r0 = 0;" + "exit;" + : + : __imm(bpf_skb_pull_data), + __imm_const(__sk_buff_data, offsetof(struct __sk_buff, data)), + __imm_const(__sk_buff_data_end, offsetof(struct __sk_buff, data_end)) + : __clobber_all + ); +} + +SEC("tc") +__description("stack_arg: null propagation rejects deref on null branch") +__failure +__msg("R{{[0-9]}} invalid mem access 'scalar'") +__naked void stack_arg_null_propagation_fail(void) +{ + asm volatile ( + "r1 = 0;" + "*(u64 *)(r10 - 8) = r1;" + /* r0 = bpf_map_lookup_elem(&map_hash_8b, &key) */ + "r2 = r10;" + "r2 += -8;" + "r1 = %[map_hash_8b] ll;" + "call %[bpf_map_lookup_elem];" + /* Store PTR_TO_MAP_VALUE_OR_NULL to outgoing arg6 slot */ + "*(u64 *)(r11 - 8) = r0;" + /* null check on r0 */ + "if r0 != 0 goto l0_%=;" + /* + * On null branch, outgoing slot is SCALAR(0). + * Call subprog that dereferences arg6 — should fail. + */ + "r1 = 0;" + "r2 = 0;" + "r3 = 0;" + "r4 = 0;" + "r5 = 0;" + "call subprog_deref_arg6;" + "l0_%=:" + "r0 = 0;" + "exit;" + : + : __imm(bpf_map_lookup_elem), + __imm_addr(map_hash_8b) + : __clobber_all + ); +} + +SEC("tc") +__description("stack_arg: missing store on one branch") +__failure +__msg("callee expects 7 args, stack arg1 is not initialized") +__naked void stack_arg_missing_store_one_branch(void) +{ + asm volatile ( + "call %[bpf_get_prandom_u32];" + "r1 = 1;" + "r2 = 2;" + "r3 = 3;" + "r4 = 4;" + "r5 = 5;" + /* Write arg7 (r11-16) before branch */ + "*(u64 *)(r11 - 16) = 20;" + "if r0 > 0 goto l0_%=;" + /* Path 1: write arg6 and call */ + "*(u64 *)(r11 - 8) = 10;" + "r1 = 1;" + "r2 = 2;" + "r3 = 3;" + "r4 = 4;" + "r5 = 5;" + "call subprog_7args;" + "goto l1_%=;" + "l0_%=:" + /* Path 2: missing arg6 store, call should fail */ + "r1 = 1;" + "r2 = 2;" + "r3 = 3;" + "r4 = 4;" + "r5 = 5;" + "call subprog_7args;" + "l1_%=:" + "r0 = 0;" + "exit;" + :: __imm(bpf_get_prandom_u32) + : __clobber_all + ); +} + +SEC("tc") +__description("stack_arg: share a store for both branches") +__success __retval(0) +__naked void stack_arg_shared_store(void) +{ + asm volatile ( + "call %[bpf_get_prandom_u32];" + "r1 = 1;" + "r2 = 2;" + "r3 = 3;" + "r4 = 4;" + "r5 = 5;" + /* Write arg7 (r11-16) before branch */ + "*(u64 *)(r11 - 16) = 20;" + "if r0 > 0 goto l0_%=;" + /* Path 1: write arg6 and call */ + "*(u64 *)(r11 - 8) = 10;" + "r1 = 1;" + "r2 = 2;" + "r3 = 3;" + "r4 = 4;" + "r5 = 5;" + "call subprog_7args;" + "goto l1_%=;" + "l0_%=:" + /* Path 2: also write arg6 and call */ + "*(u64 *)(r11 - 8) = 30;" + "r1 = 1;" + "r2 = 2;" + "r3 = 3;" + "r4 = 4;" + "r5 = 5;" + "call subprog_7args;" + "l1_%=:" + "r0 = 0;" + "exit;" + :: __imm(bpf_get_prandom_u32) + : __clobber_all + ); +} + +SEC("tc") +__description("stack_arg: write beyond max outgoing depth") +__failure +__msg("stack arg write offset -80 exceeds max 7 stack args") +__naked void stack_arg_write_beyond_max(void) +{ + asm volatile ( + "r1 = 1;" + "r2 = 2;" + "r3 = 3;" + "r4 = 4;" + "r5 = 5;" + /* Write to offset -80, way beyond any callee's needs */ + "*(u64 *)(r11 - 80) = 99;" + "*(u64 *)(r11 - 16) = 20;" + "*(u64 *)(r11 - 8) = 10;" + "call subprog_7args;" + "r0 = 0;" + "exit;" + ::: __clobber_all + ); +} + +SEC("tc") +__description("stack_arg: write unused stack arg slot") +__failure +__msg("func#0 writes 5 stack arg slots, but calls only require 2") +__naked void stack_arg_write_unused_slot(void) +{ + asm volatile ( + "r1 = 1;" + "r2 = 2;" + "r3 = 3;" + "r4 = 4;" + "r5 = 5;" + /* Write to offset -40, unused for the callee */ + "*(u64 *)(r11 - 40) = 99;" + "*(u64 *)(r11 - 16) = 20;" + "*(u64 *)(r11 - 8) = 10;" + "call subprog_7args;" + "r0 = 0;" + "exit;" + ::: __clobber_all + ); +} + +SEC("tc") +__description("stack_arg: sequential calls reuse slots") +__failure +__msg("callee expects 7 args, stack arg1 is not initialized") +__naked void stack_arg_sequential_calls(void) +{ + asm volatile ( + "r1 = 1;" + "r2 = 2;" + "r3 = 3;" + "r4 = 4;" + "r5 = 5;" + "*(u64 *)(r11 - 8) = 6;" + "*(u64 *)(r11 - 16) = 7;" + "call subprog_7args;" + "r6 = r0;" + "r1 = 1;" + "r2 = 2;" + "r3 = 3;" + "r4 = 4;" + "r5 = 5;" + "call subprog_7args;" + "r0 += r6;" + "exit;" + ::: __clobber_all + ); +} + +#else + +SEC("socket") +__description("stack_arg is not supported by compiler or jit, use a dummy test") +__success +int dummy_test(void) +{ + return 0; +} + +#endif + +char _license[] SEC("license") = "GPL"; diff --git a/tools/testing/selftests/bpf/progs/verifier_stack_arg_order.c b/tools/testing/selftests/bpf/progs/verifier_stack_arg_order.c new file mode 100644 index 000000000000..938f4a2f5482 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/verifier_stack_arg_order.c @@ -0,0 +1,126 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */ + +#include +#include +#include "bpf_misc.h" + +#if defined(__TARGET_ARCH_x86) && defined(__BPF_FEATURE_STACK_ARGUMENT) + +__noinline __used __naked +static int subprog_bad_order_6args(int a, int b, int c, int d, int e, int f) +{ + asm volatile ( + "*(u64 *)(r11 - 8) = r1;" + "r0 = *(u64 *)(r11 + 8);" + "exit;" + ::: __clobber_all + ); +} + +SEC("tc") +__description("stack_arg: r11 load after r11 store") +__failure +__msg("r11 load must be before any r11 store or call insn") +__btf_func_path("btf__verifier_stack_arg_order.bpf.o") +__naked void stack_arg_load_after_store(void) +{ + asm volatile ( + "r1 = 1;" + "r2 = 2;" + "r3 = 3;" + "r4 = 4;" + "r5 = 5;" + "*(u64 *)(r11 - 8) = 6;" + "call subprog_bad_order_6args;" + "exit;" + ::: __clobber_all + ); +} + +__noinline __used __naked +static int subprog_call_before_load_6args(int a, int b, int c, int d, int e, + int f) +{ + asm volatile ( + "call %[bpf_get_prandom_u32];" + "r0 = *(u64 *)(r11 + 8);" + "exit;" + :: __imm(bpf_get_prandom_u32) + : __clobber_all + ); +} + +SEC("tc") +__description("stack_arg: r11 load after a call") +__failure +__msg("r11 load must be before any r11 store or call insn") +__btf_func_path("btf__verifier_stack_arg_order.bpf.o") +__naked void stack_arg_load_after_call(void) +{ + asm volatile ( + "r1 = 1;" + "r2 = 2;" + "r3 = 3;" + "r4 = 4;" + "r5 = 5;" + "*(u64 *)(r11 - 8) = 6;" + "call subprog_call_before_load_6args;" + "exit;" + ::: __clobber_all + ); +} + +__noinline __used __naked +static int subprog_pruning_call_before_load_6args(int a, int b, int c, int d, + int e, int f) +{ + asm volatile ( + "if r1 s> 0 goto l0_%=;" + "goto l1_%=;" + "l0_%=:" + "call %[bpf_get_prandom_u32];" + "l1_%=:" + "r0 = *(u64 *)(r11 + 8);" + "exit;" + :: __imm(bpf_get_prandom_u32) + : __clobber_all + ); +} + +SEC("tc") +__description("stack_arg: pruning keeps r11 load ordering") +__failure +__flag(BPF_F_TEST_STATE_FREQ) +__msg("r11 load must be before any r11 store or call insn") +__btf_func_path("btf__verifier_stack_arg_order.bpf.o") +__naked void stack_arg_pruning_load_after_call(void) +{ + asm volatile ( + "call %[bpf_get_prandom_u32];" + "r1 = r0;" + "r2 = 2;" + "r3 = 3;" + "r4 = 4;" + "r5 = 5;" + "*(u64 *)(r11 - 8) = 6;" + "call subprog_pruning_call_before_load_6args;" + "exit;" + :: __imm(bpf_get_prandom_u32) + : __clobber_all + ); +} + +#else + +SEC("socket") +__description("stack_arg order is not supported by compiler or jit, use a dummy test") +__success +int dummy_test(void) +{ + return 0; +} + +#endif + +char _license[] SEC("license") = "GPL"; -- 2.53.0-Meta