From 57400dcce6c2cf3985120c4ee28b37a1f4238dbb Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Wed, 8 Mar 2023 10:41:19 -0800 Subject: [PATCH] selftests/bpf: add iterators tests Add various tests for open-coded iterators. Some of them excercise various possible coding patterns in C, some go down to low-level assembly for more control over various conditions, especially invalid ones. We also make use of bpf_for(), bpf_for_each(), bpf_repeat() macros in some of these tests. Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20230308184121.1165081-7-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- tools/testing/selftests/bpf/prog_tests/iters.c | 15 + tools/testing/selftests/bpf/progs/bpf_misc.h | 1 + tools/testing/selftests/bpf/progs/iters.c | 720 +++++++++++++++++++++ tools/testing/selftests/bpf/progs/iters_looping.c | 163 +++++ .../selftests/bpf/progs/iters_state_safety.c | 426 ++++++++++++ 5 files changed, 1325 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/iters.c create mode 100644 tools/testing/selftests/bpf/progs/iters.c create mode 100644 tools/testing/selftests/bpf/progs/iters_looping.c create mode 100644 tools/testing/selftests/bpf/progs/iters_state_safety.c diff --git a/tools/testing/selftests/bpf/prog_tests/iters.c b/tools/testing/selftests/bpf/prog_tests/iters.c new file mode 100644 index 0000000..414fb8d --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/iters.c @@ -0,0 +1,15 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */ + +#include + +#include "iters.skel.h" +#include "iters_state_safety.skel.h" +#include "iters_looping.skel.h" + +void test_iters(void) +{ + RUN_TESTS(iters_state_safety); + RUN_TESTS(iters_looping); + RUN_TESTS(iters); +} diff --git a/tools/testing/selftests/bpf/progs/bpf_misc.h b/tools/testing/selftests/bpf/progs/bpf_misc.h index 597688a..43b154a 100644 --- a/tools/testing/selftests/bpf/progs/bpf_misc.h +++ b/tools/testing/selftests/bpf/progs/bpf_misc.h @@ -36,6 +36,7 @@ #define __clobber_common "r0", "r1", "r2", "r3", "r4", "r5", "memory" #define __imm(name) [name]"i"(name) #define __imm_addr(name) [name]"i"(&name) +#define __imm_ptr(name) [name]"p"(&name) #if defined(__TARGET_ARCH_x86) #define SYSCALL_WRAPPER 1 diff --git a/tools/testing/selftests/bpf/progs/iters.c b/tools/testing/selftests/bpf/progs/iters.c new file mode 100644 index 0000000..84e5dc1 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/iters.c @@ -0,0 +1,720 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */ + +#include +#include +#include +#include "bpf_misc.h" + +#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0])) + +static volatile int zero = 0; + +int my_pid; +int arr[256]; +int small_arr[16] SEC(".data.small_arr"); + +#ifdef REAL_TEST +#define MY_PID_GUARD() if (my_pid != (bpf_get_current_pid_tgid() >> 32)) return 0 +#else +#define MY_PID_GUARD() ({ }) +#endif + +SEC("?raw_tp") +__failure __msg("math between map_value pointer and register with unbounded min value is not allowed") +int iter_err_unsafe_c_loop(const void *ctx) +{ + struct bpf_iter_num it; + int *v, i = zero; /* obscure initial value of i */ + + MY_PID_GUARD(); + + bpf_iter_num_new(&it, 0, 1000); + while ((v = bpf_iter_num_next(&it))) { + i++; + } + bpf_iter_num_destroy(&it); + + small_arr[i] = 123; /* invalid */ + + return 0; +} + +SEC("?raw_tp") +__failure __msg("unbounded memory access") +int iter_err_unsafe_asm_loop(const void *ctx) +{ + struct bpf_iter_num it; + int *v, i = 0; + + MY_PID_GUARD(); + + asm volatile ( + "r6 = %[zero];" /* iteration counter */ + "r1 = %[it];" /* iterator state */ + "r2 = 0;" + "r3 = 1000;" + "r4 = 1;" + "call %[bpf_iter_num_new];" + "loop:" + "r1 = %[it];" + "call %[bpf_iter_num_next];" + "if r0 == 0 goto out;" + "r6 += 1;" + "goto loop;" + "out:" + "r1 = %[it];" + "call %[bpf_iter_num_destroy];" + "r1 = %[small_arr];" + "r2 = r6;" + "r2 <<= 2;" + "r1 += r2;" + "*(u32 *)(r1 + 0) = r6;" /* invalid */ + : + : [it]"r"(&it), + [small_arr]"p"(small_arr), + [zero]"p"(zero), + __imm(bpf_iter_num_new), + __imm(bpf_iter_num_next), + __imm(bpf_iter_num_destroy) + : __clobber_common, "r6" + ); + + return 0; +} + +SEC("raw_tp") +__success +int iter_while_loop(const void *ctx) +{ + struct bpf_iter_num it; + int *v, i; + + MY_PID_GUARD(); + + bpf_iter_num_new(&it, 0, 3); + while ((v = bpf_iter_num_next(&it))) { + bpf_printk("ITER_BASIC: E1 VAL: v=%d", *v); + } + bpf_iter_num_destroy(&it); + + return 0; +} + +SEC("raw_tp") +__success +int iter_while_loop_auto_cleanup(const void *ctx) +{ + __attribute__((cleanup(bpf_iter_num_destroy))) struct bpf_iter_num it; + int *v, i; + + MY_PID_GUARD(); + + bpf_iter_num_new(&it, 0, 3); + while ((v = bpf_iter_num_next(&it))) { + bpf_printk("ITER_BASIC: E1 VAL: v=%d", *v); + } + /* (!) no explicit bpf_iter_num_destroy() */ + + return 0; +} + +SEC("raw_tp") +__success +int iter_for_loop(const void *ctx) +{ + struct bpf_iter_num it; + int *v, i; + + MY_PID_GUARD(); + + bpf_iter_num_new(&it, 5, 10); + for (v = bpf_iter_num_next(&it); v; v = bpf_iter_num_next(&it)) { + bpf_printk("ITER_BASIC: E2 VAL: v=%d", *v); + } + bpf_iter_num_destroy(&it); + + return 0; +} + +SEC("raw_tp") +__success +int iter_bpf_for_each_macro(const void *ctx) +{ + int *v; + + MY_PID_GUARD(); + + bpf_for_each(num, v, 5, 10) { + bpf_printk("ITER_BASIC: E2 VAL: v=%d", *v); + } + + return 0; +} + +SEC("raw_tp") +__success +int iter_bpf_for_macro(const void *ctx) +{ + int i; + + MY_PID_GUARD(); + + bpf_for(i, 5, 10) { + bpf_printk("ITER_BASIC: E2 VAL: v=%d", i); + } + + return 0; +} + +SEC("raw_tp") +__success +int iter_pragma_unroll_loop(const void *ctx) +{ + struct bpf_iter_num it; + int *v, i; + + MY_PID_GUARD(); + + bpf_iter_num_new(&it, 0, 2); +#pragma nounroll + for (i = 0; i < 3; i++) { + v = bpf_iter_num_next(&it); + bpf_printk("ITER_BASIC: E3 VAL: i=%d v=%d", i, v ? *v : -1); + } + bpf_iter_num_destroy(&it); + + return 0; +} + +SEC("raw_tp") +__success +int iter_manual_unroll_loop(const void *ctx) +{ + struct bpf_iter_num it; + int *v, i; + + MY_PID_GUARD(); + + bpf_iter_num_new(&it, 100, 200); + v = bpf_iter_num_next(&it); + bpf_printk("ITER_BASIC: E4 VAL: v=%d", v ? *v : -1); + v = bpf_iter_num_next(&it); + bpf_printk("ITER_BASIC: E4 VAL: v=%d", v ? *v : -1); + v = bpf_iter_num_next(&it); + bpf_printk("ITER_BASIC: E4 VAL: v=%d", v ? *v : -1); + v = bpf_iter_num_next(&it); + bpf_printk("ITER_BASIC: E4 VAL: v=%d\n", v ? *v : -1); + bpf_iter_num_destroy(&it); + + return 0; +} + +SEC("raw_tp") +__success +int iter_multiple_sequential_loops(const void *ctx) +{ + struct bpf_iter_num it; + int *v, i; + + MY_PID_GUARD(); + + bpf_iter_num_new(&it, 0, 3); + while ((v = bpf_iter_num_next(&it))) { + bpf_printk("ITER_BASIC: E1 VAL: v=%d", *v); + } + bpf_iter_num_destroy(&it); + + bpf_iter_num_new(&it, 5, 10); + for (v = bpf_iter_num_next(&it); v; v = bpf_iter_num_next(&it)) { + bpf_printk("ITER_BASIC: E2 VAL: v=%d", *v); + } + bpf_iter_num_destroy(&it); + + bpf_iter_num_new(&it, 0, 2); +#pragma nounroll + for (i = 0; i < 3; i++) { + v = bpf_iter_num_next(&it); + bpf_printk("ITER_BASIC: E3 VAL: i=%d v=%d", i, v ? *v : -1); + } + bpf_iter_num_destroy(&it); + + bpf_iter_num_new(&it, 100, 200); + v = bpf_iter_num_next(&it); + bpf_printk("ITER_BASIC: E4 VAL: v=%d", v ? *v : -1); + v = bpf_iter_num_next(&it); + bpf_printk("ITER_BASIC: E4 VAL: v=%d", v ? *v : -1); + v = bpf_iter_num_next(&it); + bpf_printk("ITER_BASIC: E4 VAL: v=%d", v ? *v : -1); + v = bpf_iter_num_next(&it); + bpf_printk("ITER_BASIC: E4 VAL: v=%d\n", v ? *v : -1); + bpf_iter_num_destroy(&it); + + return 0; +} + +SEC("raw_tp") +__success +int iter_limit_cond_break_loop(const void *ctx) +{ + struct bpf_iter_num it; + int *v, i = 0, sum = 0; + + MY_PID_GUARD(); + + bpf_iter_num_new(&it, 0, 10); + while ((v = bpf_iter_num_next(&it))) { + bpf_printk("ITER_SIMPLE: i=%d v=%d", i, *v); + sum += *v; + + i++; + if (i > 3) + break; + } + bpf_iter_num_destroy(&it); + + bpf_printk("ITER_SIMPLE: sum=%d\n", sum); + + return 0; +} + +SEC("raw_tp") +__success +int iter_obfuscate_counter(const void *ctx) +{ + struct bpf_iter_num it; + int *v, sum = 0; + /* Make i's initial value unknowable for verifier to prevent it from + * pruning if/else branch inside the loop body and marking i as precise. + */ + int i = zero; + + MY_PID_GUARD(); + + bpf_iter_num_new(&it, 0, 10); + while ((v = bpf_iter_num_next(&it))) { + int x; + + i += 1; + + /* If we initialized i as `int i = 0;` above, verifier would + * track that i becomes 1 on first iteration after increment + * above, and here verifier would eagerly prune else branch + * and mark i as precise, ruining open-coded iterator logic + * completely, as each next iteration would have a different + * *precise* value of i, and thus there would be no + * convergence of state. This would result in reaching maximum + * instruction limit, no matter what the limit is. + */ + if (i == 1) + x = 123; + else + x = i * 3 + 1; + + bpf_printk("ITER_OBFUSCATE_COUNTER: i=%d v=%d x=%d", i, *v, x); + + sum += x; + } + bpf_iter_num_destroy(&it); + + bpf_printk("ITER_OBFUSCATE_COUNTER: sum=%d\n", sum); + + return 0; +} + +SEC("raw_tp") +__success +int iter_search_loop(const void *ctx) +{ + struct bpf_iter_num it; + int *v, *elem = NULL; + bool found = false; + + MY_PID_GUARD(); + + bpf_iter_num_new(&it, 0, 10); + + while ((v = bpf_iter_num_next(&it))) { + bpf_printk("ITER_SEARCH_LOOP: v=%d", *v); + + if (*v == 2) { + found = true; + elem = v; + barrier_var(elem); + } + } + + /* should fail to verify if bpf_iter_num_destroy() is here */ + + if (found) + /* here found element will be wrong, we should have copied + * value to a variable, but here we want to make sure we can + * access memory after the loop anyways + */ + bpf_printk("ITER_SEARCH_LOOP: FOUND IT = %d!\n", *elem); + else + bpf_printk("ITER_SEARCH_LOOP: NOT FOUND IT!\n"); + + bpf_iter_num_destroy(&it); + + return 0; +} + +SEC("raw_tp") +__success +int iter_array_fill(const void *ctx) +{ + int sum, i; + + MY_PID_GUARD(); + + bpf_for(i, 0, ARRAY_SIZE(arr)) { + arr[i] = i * 2; + } + + sum = 0; + bpf_for(i, 0, ARRAY_SIZE(arr)) { + sum += arr[i]; + } + + bpf_printk("ITER_ARRAY_FILL: sum=%d (should be %d)\n", sum, 255 * 256); + + return 0; +} + +static int arr2d[4][5]; +static int arr2d_row_sums[4]; +static int arr2d_col_sums[5]; + +SEC("raw_tp") +__success +int iter_nested_iters(const void *ctx) +{ + int sum, row, col; + + MY_PID_GUARD(); + + bpf_for(row, 0, ARRAY_SIZE(arr2d)) { + bpf_for( col, 0, ARRAY_SIZE(arr2d[0])) { + arr2d[row][col] = row * col; + } + } + + /* zero-initialize sums */ + sum = 0; + bpf_for(row, 0, ARRAY_SIZE(arr2d)) { + arr2d_row_sums[row] = 0; + } + bpf_for(col, 0, ARRAY_SIZE(arr2d[0])) { + arr2d_col_sums[col] = 0; + } + + /* calculate sums */ + bpf_for(row, 0, ARRAY_SIZE(arr2d)) { + bpf_for(col, 0, ARRAY_SIZE(arr2d[0])) { + sum += arr2d[row][col]; + arr2d_row_sums[row] += arr2d[row][col]; + arr2d_col_sums[col] += arr2d[row][col]; + } + } + + bpf_printk("ITER_NESTED_ITERS: total sum=%d", sum); + bpf_for(row, 0, ARRAY_SIZE(arr2d)) { + bpf_printk("ITER_NESTED_ITERS: row #%d sum=%d", row, arr2d_row_sums[row]); + } + bpf_for(col, 0, ARRAY_SIZE(arr2d[0])) { + bpf_printk("ITER_NESTED_ITERS: col #%d sum=%d%s", + col, arr2d_col_sums[col], + col == ARRAY_SIZE(arr2d[0]) - 1 ? "\n" : ""); + } + + return 0; +} + +SEC("raw_tp") +__success +int iter_nested_deeply_iters(const void *ctx) +{ + int sum = 0; + + MY_PID_GUARD(); + + bpf_repeat(10) { + bpf_repeat(10) { + bpf_repeat(10) { + bpf_repeat(10) { + bpf_repeat(10) { + sum += 1; + } + } + } + } + /* validate that we can break from inside bpf_repeat() */ + break; + } + + return sum; +} + +static __noinline void fill_inner_dimension(int row) +{ + int col; + + bpf_for(col, 0, ARRAY_SIZE(arr2d[0])) { + arr2d[row][col] = row * col; + } +} + +static __noinline int sum_inner_dimension(int row) +{ + int sum = 0, col; + + bpf_for(col, 0, ARRAY_SIZE(arr2d[0])) { + sum += arr2d[row][col]; + arr2d_row_sums[row] += arr2d[row][col]; + arr2d_col_sums[col] += arr2d[row][col]; + } + + return sum; +} + +SEC("raw_tp") +__success +int iter_subprog_iters(const void *ctx) +{ + int sum, row, col; + + MY_PID_GUARD(); + + bpf_for(row, 0, ARRAY_SIZE(arr2d)) { + fill_inner_dimension(row); + } + + /* zero-initialize sums */ + sum = 0; + bpf_for(row, 0, ARRAY_SIZE(arr2d)) { + arr2d_row_sums[row] = 0; + } + bpf_for(col, 0, ARRAY_SIZE(arr2d[0])) { + arr2d_col_sums[col] = 0; + } + + /* calculate sums */ + bpf_for(row, 0, ARRAY_SIZE(arr2d)) { + sum += sum_inner_dimension(row); + } + + bpf_printk("ITER_SUBPROG_ITERS: total sum=%d", sum); + bpf_for(row, 0, ARRAY_SIZE(arr2d)) { + bpf_printk("ITER_SUBPROG_ITERS: row #%d sum=%d", + row, arr2d_row_sums[row]); + } + bpf_for(col, 0, ARRAY_SIZE(arr2d[0])) { + bpf_printk("ITER_SUBPROG_ITERS: col #%d sum=%d%s", + col, arr2d_col_sums[col], + col == ARRAY_SIZE(arr2d[0]) - 1 ? "\n" : ""); + } + + return 0; +} + +struct { + __uint(type, BPF_MAP_TYPE_ARRAY); + __type(key, int); + __type(value, int); + __uint(max_entries, 1000); +} arr_map SEC(".maps"); + +SEC("?raw_tp") +__failure __msg("invalid mem access 'scalar'") +int iter_err_too_permissive1(const void *ctx) +{ + int *map_val = NULL; + int key = 0; + + MY_PID_GUARD(); + + map_val = bpf_map_lookup_elem(&arr_map, &key); + if (!map_val) + return 0; + + bpf_repeat(1000000) { + map_val = NULL; + } + + *map_val = 123; + + return 0; +} + +SEC("?raw_tp") +__failure __msg("invalid mem access 'map_value_or_null'") +int iter_err_too_permissive2(const void *ctx) +{ + int *map_val = NULL; + int key = 0; + + MY_PID_GUARD(); + + map_val = bpf_map_lookup_elem(&arr_map, &key); + if (!map_val) + return 0; + + bpf_repeat(1000000) { + map_val = bpf_map_lookup_elem(&arr_map, &key); + } + + *map_val = 123; + + return 0; +} + +SEC("?raw_tp") +__failure __msg("invalid mem access 'map_value_or_null'") +int iter_err_too_permissive3(const void *ctx) +{ + int *map_val = NULL; + int key = 0; + bool found = false; + + MY_PID_GUARD(); + + bpf_repeat(1000000) { + map_val = bpf_map_lookup_elem(&arr_map, &key); + found = true; + } + + if (found) + *map_val = 123; + + return 0; +} + +SEC("raw_tp") +__success +int iter_tricky_but_fine(const void *ctx) +{ + int *map_val = NULL; + int key = 0; + bool found = false; + + MY_PID_GUARD(); + + bpf_repeat(1000000) { + map_val = bpf_map_lookup_elem(&arr_map, &key); + if (map_val) { + found = true; + break; + } + } + + if (found) + *map_val = 123; + + return 0; +} + +#define __bpf_memzero(p, sz) bpf_probe_read_kernel((p), (sz), 0) + +SEC("raw_tp") +__success +int iter_stack_array_loop(const void *ctx) +{ + long arr1[16], arr2[16], sum = 0; + int *v, i; + + MY_PID_GUARD(); + + /* zero-init arr1 and arr2 in such a way that verifier doesn't know + * it's all zeros; if we don't do that, we'll make BPF verifier track + * all combination of zero/non-zero stack slots for arr1/arr2, which + * will lead to O(2^(ARRAY_SIZE(arr1)+ARRAY_SIZE(arr2))) different + * states + */ + __bpf_memzero(arr1, sizeof(arr1)); + __bpf_memzero(arr2, sizeof(arr1)); + + /* validate that we can break and continue when using bpf_for() */ + bpf_for(i, 0, ARRAY_SIZE(arr1)) { + if (i & 1) { + arr1[i] = i; + continue; + } else { + arr2[i] = i; + break; + } + } + + bpf_for(i, 0, ARRAY_SIZE(arr1)) { + sum += arr1[i] + arr2[i]; + } + + return sum; +} + +static __noinline void fill(struct bpf_iter_num *it, int *arr, __u32 n, int mul) +{ + int *t, i; + + while ((t = bpf_iter_num_next(it))) { + i = *t; + if (i >= n) + break; + arr[i] = i * mul; + } +} + +static __noinline int sum(struct bpf_iter_num *it, int *arr, __u32 n) +{ + int *t, i, sum = 0;; + + while ((t = bpf_iter_num_next(it))) { + i = *t; + if (i >= n) + break; + sum += arr[i]; + } + + return sum; +} + +SEC("raw_tp") +__success +int iter_pass_iter_ptr_to_subprog(const void *ctx) +{ + int arr1[16], arr2[32]; + struct bpf_iter_num it; + int n, sum1, sum2; + + MY_PID_GUARD(); + + /* fill arr1 */ + n = ARRAY_SIZE(arr1); + bpf_iter_num_new(&it, 0, n); + fill(&it, arr1, n, 2); + bpf_iter_num_destroy(&it); + + /* fill arr2 */ + n = ARRAY_SIZE(arr2); + bpf_iter_num_new(&it, 0, n); + fill(&it, arr2, n, 10); + bpf_iter_num_destroy(&it); + + /* sum arr1 */ + n = ARRAY_SIZE(arr1); + bpf_iter_num_new(&it, 0, n); + sum1 = sum(&it, arr1, n); + bpf_iter_num_destroy(&it); + + /* sum arr2 */ + n = ARRAY_SIZE(arr2); + bpf_iter_num_new(&it, 0, n); + sum2 = sum(&it, arr2, n); + bpf_iter_num_destroy(&it); + + bpf_printk("sum1=%d, sum2=%d", sum1, sum2); + + return 0; +} + +char _license[] SEC("license") = "GPL"; diff --git a/tools/testing/selftests/bpf/progs/iters_looping.c b/tools/testing/selftests/bpf/progs/iters_looping.c new file mode 100644 index 0000000..05fa5ce --- /dev/null +++ b/tools/testing/selftests/bpf/progs/iters_looping.c @@ -0,0 +1,163 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */ + +#include +#include +#include +#include +#include "bpf_misc.h" + +char _license[] SEC("license") = "GPL"; + +#define ITER_HELPERS \ + __imm(bpf_iter_num_new), \ + __imm(bpf_iter_num_next), \ + __imm(bpf_iter_num_destroy) + +SEC("?raw_tp") +__success +int force_clang_to_emit_btf_for_externs(void *ctx) +{ + /* we need this as a workaround to enforce compiler emitting BTF + * information for bpf_iter_num_{new,next,destroy}() kfuncs, + * as, apparently, it doesn't emit it for symbols only referenced from + * assembly (or cleanup attribute, for that matter, as well) + */ + bpf_repeat(0); + + return 0; +} + +SEC("?raw_tp") +__success +int consume_first_item_only(void *ctx) +{ + struct bpf_iter_num iter; + + asm volatile ( + /* create iterator */ + "r1 = %[iter];" + "r2 = 0;" + "r3 = 1000;" + "call %[bpf_iter_num_new];" + + /* consume first item */ + "r1 = %[iter];" + "call %[bpf_iter_num_next];" + + "if r0 == 0 goto +1;" + "r0 = *(u32 *)(r0 + 0);" + + /* destroy iterator */ + "r1 = %[iter];" + "call %[bpf_iter_num_destroy];" + : + : __imm_ptr(iter), ITER_HELPERS + : __clobber_common + ); + + return 0; +} + +SEC("?raw_tp") +__failure __msg("R0 invalid mem access 'scalar'") +int missing_null_check_fail(void *ctx) +{ + struct bpf_iter_num iter; + + asm volatile ( + /* create iterator */ + "r1 = %[iter];" + "r2 = 0;" + "r3 = 1000;" + "call %[bpf_iter_num_new];" + + /* consume first element */ + "r1 = %[iter];" + "call %[bpf_iter_num_next];" + + /* FAIL: deref with no NULL check */ + "r1 = *(u32 *)(r0 + 0);" + + /* destroy iterator */ + "r1 = %[iter];" + "call %[bpf_iter_num_destroy];" + : + : __imm_ptr(iter), ITER_HELPERS + : __clobber_common + ); + + return 0; +} + +SEC("?raw_tp") +__failure +__msg("invalid access to memory, mem_size=4 off=0 size=8") +__msg("R0 min value is outside of the allowed memory range") +int wrong_sized_read_fail(void *ctx) +{ + struct bpf_iter_num iter; + + asm volatile ( + /* create iterator */ + "r1 = %[iter];" + "r2 = 0;" + "r3 = 1000;" + "call %[bpf_iter_num_new];" + + /* consume first element */ + "r1 = %[iter];" + "call %[bpf_iter_num_next];" + + "if r0 == 0 goto +1;" + /* FAIL: deref more than available 4 bytes */ + "r0 = *(u64 *)(r0 + 0);" + + /* destroy iterator */ + "r1 = %[iter];" + "call %[bpf_iter_num_destroy];" + : + : __imm_ptr(iter), ITER_HELPERS + : __clobber_common + ); + + return 0; +} + +SEC("?raw_tp") +__success __log_level(2) +__flag(BPF_F_TEST_STATE_FREQ) +int simplest_loop(void *ctx) +{ + struct bpf_iter_num iter; + + asm volatile ( + "r6 = 0;" /* init sum */ + + /* create iterator */ + "r1 = %[iter];" + "r2 = 0;" + "r3 = 10;" + "call %[bpf_iter_num_new];" + + "1:" + /* consume next item */ + "r1 = %[iter];" + "call %[bpf_iter_num_next];" + + "if r0 == 0 goto 2f;" + "r0 = *(u32 *)(r0 + 0);" + "r6 += r0;" /* accumulate sum */ + "goto 1b;" + + "2:" + /* destroy iterator */ + "r1 = %[iter];" + "call %[bpf_iter_num_destroy];" + : + : __imm_ptr(iter), ITER_HELPERS + : __clobber_common, "r6" + ); + + return 0; +} diff --git a/tools/testing/selftests/bpf/progs/iters_state_safety.c b/tools/testing/selftests/bpf/progs/iters_state_safety.c new file mode 100644 index 0000000..d47e59a --- /dev/null +++ b/tools/testing/selftests/bpf/progs/iters_state_safety.c @@ -0,0 +1,426 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2022 Facebook */ + +#include +#include +#include +#include +#include "bpf_misc.h" + +char _license[] SEC("license") = "GPL"; + +#define ITER_HELPERS \ + __imm(bpf_iter_num_new), \ + __imm(bpf_iter_num_next), \ + __imm(bpf_iter_num_destroy) + +SEC("?raw_tp") +__success +int force_clang_to_emit_btf_for_externs(void *ctx) +{ + /* we need this as a workaround to enforce compiler emitting BTF + * information for bpf_iter_num_{new,next,destroy}() kfuncs, + * as, apparently, it doesn't emit it for symbols only referenced from + * assembly (or cleanup attribute, for that matter, as well) + */ + bpf_repeat(0); + + return 0; +} + +SEC("?raw_tp") +__success __log_level(2) +__msg("fp-8_w=iter_num(ref_id=1,state=active,depth=0)") +int create_and_destroy(void *ctx) +{ + struct bpf_iter_num iter; + + asm volatile ( + /* create iterator */ + "r1 = %[iter];" + "r2 = 0;" + "r3 = 1000;" + "call %[bpf_iter_num_new];" + /* destroy iterator */ + "r1 = %[iter];" + "call %[bpf_iter_num_destroy];" + : + : __imm_ptr(iter), ITER_HELPERS + : __clobber_common + ); + + return 0; +} + +SEC("?raw_tp") +__failure __msg("Unreleased reference id=1") +int create_and_forget_to_destroy_fail(void *ctx) +{ + struct bpf_iter_num iter; + + asm volatile ( + /* create iterator */ + "r1 = %[iter];" + "r2 = 0;" + "r3 = 1000;" + "call %[bpf_iter_num_new];" + : + : __imm_ptr(iter), ITER_HELPERS + : __clobber_common + ); + + return 0; +} + +SEC("?raw_tp") +__failure __msg("expected an initialized iter_num as arg #1") +int destroy_without_creating_fail(void *ctx) +{ + /* init with zeros to stop verifier complaining about uninit stack */ + struct bpf_iter_num iter; + + asm volatile ( + "r1 = %[iter];" + "call %[bpf_iter_num_destroy];" + : + : __imm_ptr(iter), ITER_HELPERS + : __clobber_common + ); + + return 0; +} + +SEC("?raw_tp") +__failure __msg("expected an initialized iter_num as arg #1") +int compromise_iter_w_direct_write_fail(void *ctx) +{ + struct bpf_iter_num iter; + + asm volatile ( + /* create iterator */ + "r1 = %[iter];" + "r2 = 0;" + "r3 = 1000;" + "call %[bpf_iter_num_new];" + + /* directly write over first half of iter state */ + "*(u64 *)(%[iter] + 0) = r0;" + + /* (attempt to) destroy iterator */ + "r1 = %[iter];" + "call %[bpf_iter_num_destroy];" + : + : __imm_ptr(iter), ITER_HELPERS + : __clobber_common + ); + + return 0; +} + +SEC("?raw_tp") +__failure __msg("Unreleased reference id=1") +int compromise_iter_w_direct_write_and_skip_destroy_fail(void *ctx) +{ + struct bpf_iter_num iter; + + asm volatile ( + /* create iterator */ + "r1 = %[iter];" + "r2 = 0;" + "r3 = 1000;" + "call %[bpf_iter_num_new];" + + /* directly write over first half of iter state */ + "*(u64 *)(%[iter] + 0) = r0;" + + /* don't destroy iter, leaking ref, which should fail */ + : + : __imm_ptr(iter), ITER_HELPERS + : __clobber_common + ); + + return 0; +} + +SEC("?raw_tp") +__failure __msg("expected an initialized iter_num as arg #1") +int compromise_iter_w_helper_write_fail(void *ctx) +{ + struct bpf_iter_num iter; + + asm volatile ( + /* create iterator */ + "r1 = %[iter];" + "r2 = 0;" + "r3 = 1000;" + "call %[bpf_iter_num_new];" + + /* overwrite 8th byte with bpf_probe_read_kernel() */ + "r1 = %[iter];" + "r1 += 7;" + "r2 = 1;" + "r3 = 0;" /* NULL */ + "call %[bpf_probe_read_kernel];" + + /* (attempt to) destroy iterator */ + "r1 = %[iter];" + "call %[bpf_iter_num_destroy];" + : + : __imm_ptr(iter), ITER_HELPERS, __imm(bpf_probe_read_kernel) + : __clobber_common + ); + + return 0; +} + +static __noinline void subprog_with_iter(void) +{ + struct bpf_iter_num iter; + + bpf_iter_num_new(&iter, 0, 1); + + return; +} + +SEC("?raw_tp") +__failure +/* ensure there was a call to subprog, which might happen without __noinline */ +__msg("returning from callee:") +__msg("Unreleased reference id=1") +int leak_iter_from_subprog_fail(void *ctx) +{ + subprog_with_iter(); + + return 0; +} + +SEC("?raw_tp") +__success __log_level(2) +__msg("fp-8_w=iter_num(ref_id=1,state=active,depth=0)") +int valid_stack_reuse(void *ctx) +{ + struct bpf_iter_num iter; + + asm volatile ( + /* create iterator */ + "r1 = %[iter];" + "r2 = 0;" + "r3 = 1000;" + "call %[bpf_iter_num_new];" + /* destroy iterator */ + "r1 = %[iter];" + "call %[bpf_iter_num_destroy];" + + /* now reuse same stack slots */ + + /* create iterator */ + "r1 = %[iter];" + "r2 = 0;" + "r3 = 1000;" + "call %[bpf_iter_num_new];" + /* destroy iterator */ + "r1 = %[iter];" + "call %[bpf_iter_num_destroy];" + : + : __imm_ptr(iter), ITER_HELPERS + : __clobber_common + ); + + return 0; +} + +SEC("?raw_tp") +__failure __msg("expected uninitialized iter_num as arg #1") +int double_create_fail(void *ctx) +{ + struct bpf_iter_num iter; + + asm volatile ( + /* create iterator */ + "r1 = %[iter];" + "r2 = 0;" + "r3 = 1000;" + "call %[bpf_iter_num_new];" + /* (attempt to) create iterator again */ + "r1 = %[iter];" + "r2 = 0;" + "r3 = 1000;" + "call %[bpf_iter_num_new];" + /* destroy iterator */ + "r1 = %[iter];" + "call %[bpf_iter_num_destroy];" + : + : __imm_ptr(iter), ITER_HELPERS + : __clobber_common + ); + + return 0; +} + +SEC("?raw_tp") +__failure __msg("expected an initialized iter_num as arg #1") +int double_destroy_fail(void *ctx) +{ + struct bpf_iter_num iter; + + asm volatile ( + /* create iterator */ + "r1 = %[iter];" + "r2 = 0;" + "r3 = 1000;" + "call %[bpf_iter_num_new];" + /* destroy iterator */ + "r1 = %[iter];" + "call %[bpf_iter_num_destroy];" + /* (attempt to) destroy iterator again */ + "r1 = %[iter];" + "call %[bpf_iter_num_destroy];" + : + : __imm_ptr(iter), ITER_HELPERS + : __clobber_common + ); + + return 0; +} + +SEC("?raw_tp") +__failure __msg("expected an initialized iter_num as arg #1") +int next_without_new_fail(void *ctx) +{ + struct bpf_iter_num iter; + + asm volatile ( + /* don't create iterator and try to iterate*/ + "r1 = %[iter];" + "call %[bpf_iter_num_next];" + /* destroy iterator */ + "r1 = %[iter];" + "call %[bpf_iter_num_destroy];" + : + : __imm_ptr(iter), ITER_HELPERS + : __clobber_common + ); + + return 0; +} + +SEC("?raw_tp") +__failure __msg("expected an initialized iter_num as arg #1") +int next_after_destroy_fail(void *ctx) +{ + struct bpf_iter_num iter; + + asm volatile ( + /* create iterator */ + "r1 = %[iter];" + "r2 = 0;" + "r3 = 1000;" + "call %[bpf_iter_num_new];" + /* destroy iterator */ + "r1 = %[iter];" + "call %[bpf_iter_num_destroy];" + /* don't create iterator and try to iterate*/ + "r1 = %[iter];" + "call %[bpf_iter_num_next];" + : + : __imm_ptr(iter), ITER_HELPERS + : __clobber_common + ); + + return 0; +} + +SEC("?raw_tp") +__failure __msg("invalid read from stack") +int __naked read_from_iter_slot_fail(void) +{ + asm volatile ( + /* r6 points to struct bpf_iter_num on the stack */ + "r6 = r10;" + "r6 += -24;" + + /* create iterator */ + "r1 = r6;" + "r2 = 0;" + "r3 = 1000;" + "call %[bpf_iter_num_new];" + + /* attemp to leak bpf_iter_num state */ + "r7 = *(u64 *)(r6 + 0);" + "r8 = *(u64 *)(r6 + 8);" + + /* destroy iterator */ + "r1 = r6;" + "call %[bpf_iter_num_destroy];" + + /* leak bpf_iter_num state */ + "r0 = r7;" + "if r7 > r8 goto +1;" + "r0 = r8;" + "exit;" + : + : ITER_HELPERS + : __clobber_common, "r6", "r7", "r8" + ); +} + +int zero; + +SEC("?raw_tp") +__failure +__flag(BPF_F_TEST_STATE_FREQ) +__msg("Unreleased reference") +int stacksafe_should_not_conflate_stack_spill_and_iter(void *ctx) +{ + struct bpf_iter_num iter; + + asm volatile ( + /* Create a fork in logic, with general setup as follows: + * - fallthrough (first) path is valid; + * - branch (second) path is invalid. + * Then depending on what we do in fallthrough vs branch path, + * we try to detect bugs in func_states_equal(), regsafe(), + * refsafe(), stack_safe(), and similar by tricking verifier + * into believing that branch state is a valid subset of + * a fallthrough state. Verifier should reject overall + * validation, unless there is a bug somewhere in verifier + * logic. + */ + "call %[bpf_get_prandom_u32];" + "r6 = r0;" + "call %[bpf_get_prandom_u32];" + "r7 = r0;" + + "if r6 > r7 goto bad;" /* fork */ + + /* spill r6 into stack slot of bpf_iter_num var */ + "*(u64 *)(%[iter] + 0) = r6;" + + "goto skip_bad;" + + "bad:" + /* create iterator in the same stack slot */ + "r1 = %[iter];" + "r2 = 0;" + "r3 = 1000;" + "call %[bpf_iter_num_new];" + + /* but then forget about it and overwrite it back to r6 spill */ + "*(u64 *)(%[iter] + 0) = r6;" + + "skip_bad:" + "goto +0;" /* force checkpoint */ + + /* corrupt stack slots, if they are really dynptr */ + "*(u64 *)(%[iter] + 0) = r6;" + : + : __imm_ptr(iter), + __imm_addr(zero), + __imm(bpf_get_prandom_u32), + __imm(bpf_dynptr_from_mem), + ITER_HELPERS + : __clobber_common, "r6", "r7" + ); + + return 0; +} -- 2.7.4