Add verifier coverage for the three cases affected by preserving the full pointer state across scalar += pointer: stack frame number inheritance, readonly-untrusted memory access, and dynptr data-slice invalidation.
Signed-off-by: Yiyang Chen <[email protected]> --- .../testing/selftests/bpf/progs/dynptr_fail.c | 31 ++++++++++++++ .../bpf/progs/mem_rdonly_untrusted.c | 17 ++++++++ .../bpf/progs/verifier_basic_stack.c | 41 +++++++++++++++++++ 3 files changed, 89 insertions(+) diff --git a/tools/testing/selftests/bpf/progs/dynptr_fail.c b/tools/testing/selftests/bpf/progs/dynptr_fail.c index 94489ac64da8e..7da4266bae09b 100644 --- a/tools/testing/selftests/bpf/progs/dynptr_fail.c +++ b/tools/testing/selftests/bpf/progs/dynptr_fail.c @@ -1635,6 +1635,37 @@ static int callback(__u32 index, void *data) return 0; } +/* A commuted add should preserve the parent id of a dynptr data slice. + */ +SEC("?raw_tp") +__failure __msg("invalid mem access 'scalar'") +int dynptr_slice_commuted_invalidate(void *ctx) +{ + struct bpf_dynptr ptr; + __u32 *slice, *derived; + + bpf_ringbuf_reserve_dynptr(&ringbuf, sizeof(__u32), 0, &ptr); + + slice = bpf_dynptr_data(&ptr, 0, sizeof(__u32)); + if (!slice) + goto done; + + asm volatile ("%[dst] = 0;" + "%[dst] += %[src];" + "%[src] = 0;" + : [dst]"=&r"(derived), [src]"+r"(slice) + : + : "memory"); + + bpf_ringbuf_discard_dynptr(&ptr, 0); + val = *derived; + return 0; + +done: + bpf_ringbuf_discard_dynptr(&ptr, 0); + return 0; +} + /* If the dynptr is written into in a callback function, its data * slices should be invalidated as well. */ diff --git a/tools/testing/selftests/bpf/progs/mem_rdonly_untrusted.c b/tools/testing/selftests/bpf/progs/mem_rdonly_untrusted.c index 5b4453747c230..f166fff8f2176 100644 --- a/tools/testing/selftests/bpf/progs/mem_rdonly_untrusted.c +++ b/tools/testing/selftests/bpf/progs/mem_rdonly_untrusted.c @@ -226,4 +226,21 @@ int null_check(void *ctx) return 0; } +SEC("socket") +__success +__retval(1) +int ldx_is_ok_commuted_addr(void *ctx) +{ + int v, *p, *derived; + + v = 1; + p = bpf_rdonly_cast(&v, 0); + asm volatile ("%[dst] = 0;" + "%[dst] += %[src];" + : [dst]"=&r"(derived) + : [src]"r"(p) + : "memory"); + return *derived; +} + char _license[] SEC("license") = "GPL"; diff --git a/tools/testing/selftests/bpf/progs/verifier_basic_stack.c b/tools/testing/selftests/bpf/progs/verifier_basic_stack.c index fb62e09f21146..d3df7a9f1d8c8 100644 --- a/tools/testing/selftests/bpf/progs/verifier_basic_stack.c +++ b/tools/testing/selftests/bpf/progs/verifier_basic_stack.c @@ -97,4 +97,45 @@ __naked void misaligned_read_from_stack(void) " ::: __clobber_all); } +SEC("socket") +__description("stack pointer arithmetic preserves frame number") +__failure __msg("R7 invalid mem access 'scalar'") +__naked void stack_ptr_arith_preserves_frameno(void) +{ + asm volatile ("\ + r3 = 0; \ + *(u64 *)(r10 - 8) = r3; \ + r1 = %[map_hash_8b] ll; \ + r2 = r10; \ + r2 += -8; \ + call %[bpf_map_lookup_elem]; \ + if r0 != 0 goto +2; \ + r0 = 0; \ + exit; \ + r1 = r0; \ + r2 = 0; \ + r3 = 0; \ + call stack_ptr_arith_preserves_frameno_subprog;\ + r0 = 0; \ + exit; \ + ": + : __imm(bpf_map_lookup_elem), + __imm_addr(map_hash_8b) + : __clobber_all); +} + +static __used __naked void stack_ptr_arith_preserves_frameno_subprog(void) +{ + asm volatile ("\ + *(u64 *)(r10 - 8) = r1; \ + r6 = -8; \ + r6 += r10; \ + *(u64 *)(r6 + 0) = r2; \ + r7 = *(u64 *)(r10 - 8); \ + *(u64 *)(r7 + 0) = r3; \ + r0 = 0; \ + exit; \ + "::: __clobber_all); +} + char _license[] SEC("license") = "GPL"; -- 2.34.1
