[ Upstream commit 389ede06c297 ] These test cases try to hide read and precision marks from loop convergence logic: marks would only be assigned on subsequent loop iterations or after exploring states pushed to env->head stack first. Without verifier fix to use exact states comparison logic for iterators convergence these tests (except 'triple_continue') would be errorneously marked as safe. Signed-off-by: Eduard Zingerman <eddyz87@xxxxxxxxx> Link: https://lore.kernel.org/r/20231024000917.12153-5-eddyz87@xxxxxxxxx Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx> --- tools/testing/selftests/bpf/progs/iters.c | 518 ++++++++++++++++++++++ 1 file changed, 518 insertions(+) diff --git a/tools/testing/selftests/bpf/progs/iters.c b/tools/testing/selftests/bpf/progs/iters.c index 6b9b3c56f009..764a68420c3e 100644 --- a/tools/testing/selftests/bpf/progs/iters.c +++ b/tools/testing/selftests/bpf/progs/iters.c @@ -14,6 +14,13 @@ int my_pid; int arr[256]; int small_arr[16] SEC(".data.small_arr"); +struct { + __uint(type, BPF_MAP_TYPE_HASH); + __uint(max_entries, 10); + __type(key, int); + __type(value, int); +} amap SEC(".maps"); + #ifdef REAL_TEST #define MY_PID_GUARD() if (my_pid != (bpf_get_current_pid_tgid() >> 32)) return 0 #else @@ -716,4 +723,515 @@ int iter_pass_iter_ptr_to_subprog(const void *ctx) return 0; } +SEC("?raw_tp") +__failure +__msg("R1 type=scalar expected=fp") +__naked int delayed_read_mark(void) +{ + /* This is equivalent to C program below. + * The call to bpf_iter_num_next() is reachable with r7 values &fp[-16] and 0xdead. + * State with r7=&fp[-16] is visited first and follows r6 != 42 ... continue branch. + * At this point iterator next() call is reached with r7 that has no read mark. + * Loop body with r7=0xdead would only be visited if verifier would decide to continue + * with second loop iteration. Absence of read mark on r7 might affect state + * equivalent logic used for iterator convergence tracking. + * + * r7 = &fp[-16] + * fp[-16] = 0 + * r6 = bpf_get_prandom_u32() + * bpf_iter_num_new(&fp[-8], 0, 10) + * while (bpf_iter_num_next(&fp[-8])) { + * r6++ + * if (r6 != 42) { + * r7 = 0xdead + * continue; + * } + * bpf_probe_read_user(r7, 8, 0xdeadbeef); // this is not safe + * } + * bpf_iter_num_destroy(&fp[-8]) + * return 0 + */ + asm volatile ( + "r7 = r10;" + "r7 += -16;" + "r0 = 0;" + "*(u64 *)(r7 + 0) = r0;" + "call %[bpf_get_prandom_u32];" + "r6 = r0;" + "r1 = r10;" + "r1 += -8;" + "r2 = 0;" + "r3 = 10;" + "call %[bpf_iter_num_new];" + "1:" + "r1 = r10;" + "r1 += -8;" + "call %[bpf_iter_num_next];" + "if r0 == 0 goto 2f;" + "r6 += 1;" + "if r6 != 42 goto 3f;" + "r7 = 0xdead;" + "goto 1b;" + "3:" + "r1 = r7;" + "r2 = 8;" + "r3 = 0xdeadbeef;" + "call %[bpf_probe_read_user];" + "goto 1b;" + "2:" + "r1 = r10;" + "r1 += -8;" + "call %[bpf_iter_num_destroy];" + "r0 = 0;" + "exit;" + : + : __imm(bpf_get_prandom_u32), + __imm(bpf_iter_num_new), + __imm(bpf_iter_num_next), + __imm(bpf_iter_num_destroy), + __imm(bpf_probe_read_user) + : __clobber_all + ); +} + +SEC("?raw_tp") +__failure +__msg("math between fp pointer and register with unbounded") +__naked int delayed_precision_mark(void) +{ + /* This is equivalent to C program below. + * The test is similar to delayed_iter_mark but verifies that incomplete + * precision don't fool verifier. + * The call to bpf_iter_num_next() is reachable with r7 values -16 and -32. + * State with r7=-16 is visited first and follows r6 != 42 ... continue branch. + * At this point iterator next() call is reached with r7 that has no read + * and precision marks. + * Loop body with r7=-32 would only be visited if verifier would decide to continue + * with second loop iteration. Absence of precision mark on r7 might affect state + * equivalent logic used for iterator convergence tracking. + * + * r8 = 0 + * fp[-16] = 0 + * r7 = -16 + * r6 = bpf_get_prandom_u32() + * bpf_iter_num_new(&fp[-8], 0, 10) + * while (bpf_iter_num_next(&fp[-8])) { + * if (r6 != 42) { + * r7 = -32 + * r6 = bpf_get_prandom_u32() + * continue; + * } + * r0 = r10 + * r0 += r7 + * r8 = *(u64 *)(r0 + 0) // this is not safe + * r6 = bpf_get_prandom_u32() + * } + * bpf_iter_num_destroy(&fp[-8]) + * return r8 + */ + asm volatile ( + "r8 = 0;" + "*(u64 *)(r10 - 16) = r8;" + "r7 = -16;" + "call %[bpf_get_prandom_u32];" + "r6 = r0;" + "r1 = r10;" + "r1 += -8;" + "r2 = 0;" + "r3 = 10;" + "call %[bpf_iter_num_new];" + "1:" + "r1 = r10;" + "r1 += -8;\n" + "call %[bpf_iter_num_next];" + "if r0 == 0 goto 2f;" + "if r6 != 42 goto 3f;" + "r7 = -32;" + "call %[bpf_get_prandom_u32];" + "r6 = r0;" + "goto 1b;\n" + "3:" + "r0 = r10;" + "r0 += r7;" + "r8 = *(u64 *)(r0 + 0);" + "call %[bpf_get_prandom_u32];" + "r6 = r0;" + "goto 1b;\n" + "2:" + "r1 = r10;" + "r1 += -8;" + "call %[bpf_iter_num_destroy];" + "r0 = r8;" + "exit;" + : + : __imm(bpf_get_prandom_u32), + __imm(bpf_iter_num_new), + __imm(bpf_iter_num_next), + __imm(bpf_iter_num_destroy), + __imm(bpf_probe_read_user) + : __clobber_all + ); +} + +SEC("?raw_tp") +__failure +__msg("math between fp pointer and register with unbounded") +__flag(BPF_F_TEST_STATE_FREQ) +__naked int loop_state_deps1(void) +{ + /* This is equivalent to C program below. + * + * The case turns out to be tricky in a sense that: + * - states with c=-25 are explored only on a second iteration + * of the outer loop; + * - states with read+precise mark on c are explored only on + * second iteration of the inner loop and in a state which + * is pushed to states stack first. + * + * Depending on the details of iterator convergence logic + * verifier might stop states traversal too early and miss + * unsafe c=-25 memory access. + * + * j = iter_new(); // fp[-16] + * a = 0; // r6 + * b = 0; // r7 + * c = -24; // r8 + * while (iter_next(j)) { + * i = iter_new(); // fp[-8] + * a = 0; // r6 + * b = 0; // r7 + * while (iter_next(i)) { + * if (a == 1) { + * a = 0; + * b = 1; + * } else if (a == 0) { + * a = 1; + * if (random() == 42) + * continue; + * if (b == 1) { + * *(r10 + c) = 7; // this is not safe + * iter_destroy(i); + * iter_destroy(j); + * return; + * } + * } + * } + * iter_destroy(i); + * a = 0; + * b = 0; + * c = -25; + * } + * iter_destroy(j); + * return; + */ + asm volatile ( + "r1 = r10;" + "r1 += -16;" + "r2 = 0;" + "r3 = 10;" + "call %[bpf_iter_num_new];" + "r6 = 0;" + "r7 = 0;" + "r8 = -24;" + "j_loop_%=:" + "r1 = r10;" + "r1 += -16;" + "call %[bpf_iter_num_next];" + "if r0 == 0 goto j_loop_end_%=;" + "r1 = r10;" + "r1 += -8;" + "r2 = 0;" + "r3 = 10;" + "call %[bpf_iter_num_new];" + "r6 = 0;" + "r7 = 0;" + "i_loop_%=:" + "r1 = r10;" + "r1 += -8;" + "call %[bpf_iter_num_next];" + "if r0 == 0 goto i_loop_end_%=;" + "check_one_r6_%=:" + "if r6 != 1 goto check_zero_r6_%=;" + "r6 = 0;" + "r7 = 1;" + "goto i_loop_%=;" + "check_zero_r6_%=:" + "if r6 != 0 goto i_loop_%=;" + "r6 = 1;" + "call %[bpf_get_prandom_u32];" + "if r0 != 42 goto check_one_r7_%=;" + "goto i_loop_%=;" + "check_one_r7_%=:" + "if r7 != 1 goto i_loop_%=;" + "r0 = r10;" + "r0 += r8;" + "r1 = 7;" + "*(u64 *)(r0 + 0) = r1;" + "r1 = r10;" + "r1 += -8;" + "call %[bpf_iter_num_destroy];" + "r1 = r10;" + "r1 += -16;" + "call %[bpf_iter_num_destroy];" + "r0 = 0;" + "exit;" + "i_loop_end_%=:" + "r1 = r10;" + "r1 += -8;" + "call %[bpf_iter_num_destroy];" + "r6 = 0;" + "r7 = 0;" + "r8 = -25;" + "goto j_loop_%=;" + "j_loop_end_%=:" + "r1 = r10;" + "r1 += -16;" + "call %[bpf_iter_num_destroy];" + "r0 = 0;" + "exit;" + : + : __imm(bpf_get_prandom_u32), + __imm(bpf_iter_num_new), + __imm(bpf_iter_num_next), + __imm(bpf_iter_num_destroy) + : __clobber_all + ); +} + +SEC("?raw_tp") +__success +__naked int triple_continue(void) +{ + /* This is equivalent to C program below. + * High branching factor of the loop body turned out to be + * problematic for one of the iterator convergence tracking + * algorithms explored. + * + * r6 = bpf_get_prandom_u32() + * bpf_iter_num_new(&fp[-8], 0, 10) + * while (bpf_iter_num_next(&fp[-8])) { + * if (bpf_get_prandom_u32() != 42) + * continue; + * if (bpf_get_prandom_u32() != 42) + * continue; + * if (bpf_get_prandom_u32() != 42) + * continue; + * r0 += 0; + * } + * bpf_iter_num_destroy(&fp[-8]) + * return 0 + */ + asm volatile ( + "r1 = r10;" + "r1 += -8;" + "r2 = 0;" + "r3 = 10;" + "call %[bpf_iter_num_new];" + "loop_%=:" + "r1 = r10;" + "r1 += -8;" + "call %[bpf_iter_num_next];" + "if r0 == 0 goto loop_end_%=;" + "call %[bpf_get_prandom_u32];" + "if r0 != 42 goto loop_%=;" + "call %[bpf_get_prandom_u32];" + "if r0 != 42 goto loop_%=;" + "call %[bpf_get_prandom_u32];" + "if r0 != 42 goto loop_%=;" + "r0 += 0;" + "goto loop_%=;" + "loop_end_%=:" + "r1 = r10;" + "r1 += -8;" + "call %[bpf_iter_num_destroy];" + "r0 = 0;" + "exit;" + : + : __imm(bpf_get_prandom_u32), + __imm(bpf_iter_num_new), + __imm(bpf_iter_num_next), + __imm(bpf_iter_num_destroy) + : __clobber_all + ); +} + +SEC("?raw_tp") +__success +__naked int widen_spill(void) +{ + /* This is equivalent to C program below. + * The counter is stored in fp[-16], if this counter is not widened + * verifier states representing loop iterations would never converge. + * + * fp[-16] = 0 + * bpf_iter_num_new(&fp[-8], 0, 10) + * while (bpf_iter_num_next(&fp[-8])) { + * r0 = fp[-16]; + * r0 += 1; + * fp[-16] = r0; + * } + * bpf_iter_num_destroy(&fp[-8]) + * return 0 + */ + asm volatile ( + "r0 = 0;" + "*(u64 *)(r10 - 16) = r0;" + "r1 = r10;" + "r1 += -8;" + "r2 = 0;" + "r3 = 10;" + "call %[bpf_iter_num_new];" + "loop_%=:" + "r1 = r10;" + "r1 += -8;" + "call %[bpf_iter_num_next];" + "if r0 == 0 goto loop_end_%=;" + "r0 = *(u64 *)(r10 - 16);" + "r0 += 1;" + "*(u64 *)(r10 - 16) = r0;" + "goto loop_%=;" + "loop_end_%=:" + "r1 = r10;" + "r1 += -8;" + "call %[bpf_iter_num_destroy];" + "r0 = 0;" + "exit;" + : + : __imm(bpf_iter_num_new), + __imm(bpf_iter_num_next), + __imm(bpf_iter_num_destroy) + : __clobber_all + ); +} + +SEC("raw_tp") +__success +__naked int checkpoint_states_deletion(void) +{ + /* This is equivalent to C program below. + * + * int *a, *b, *c, *d, *e, *f; + * int i, sum = 0; + * bpf_for(i, 0, 10) { + * a = bpf_map_lookup_elem(&amap, &i); + * b = bpf_map_lookup_elem(&amap, &i); + * c = bpf_map_lookup_elem(&amap, &i); + * d = bpf_map_lookup_elem(&amap, &i); + * e = bpf_map_lookup_elem(&amap, &i); + * f = bpf_map_lookup_elem(&amap, &i); + * if (a) sum += 1; + * if (b) sum += 1; + * if (c) sum += 1; + * if (d) sum += 1; + * if (e) sum += 1; + * if (f) sum += 1; + * } + * return 0; + * + * The body of the loop spawns multiple simulation paths + * with different combination of NULL/non-NULL information for a/b/c/d/e/f. + * Each combination is unique from states_equal() point of view. + * Explored states checkpoint is created after each iterator next call. + * Iterator convergence logic expects that eventually current state + * would get equal to one of the explored states and thus loop + * exploration would be finished (at-least for a specific path). + * Verifier evicts explored states with high miss to hit ratio + * to to avoid comparing current state with too many explored + * states per instruction. + * This test is designed to "stress test" eviction policy defined using formula: + * + * sl->miss_cnt > sl->hit_cnt * N + N // if true sl->state is evicted + * + * Currently N is set to 64, which allows for 6 variables in this test. + */ + asm volatile ( + "r6 = 0;" /* a */ + "r7 = 0;" /* b */ + "r8 = 0;" /* c */ + "*(u64 *)(r10 - 24) = r6;" /* d */ + "*(u64 *)(r10 - 32) = r6;" /* e */ + "*(u64 *)(r10 - 40) = r6;" /* f */ + "r9 = 0;" /* sum */ + "r1 = r10;" + "r1 += -8;" + "r2 = 0;" + "r3 = 10;" + "call %[bpf_iter_num_new];" + "loop_%=:" + "r1 = r10;" + "r1 += -8;" + "call %[bpf_iter_num_next];" + "if r0 == 0 goto loop_end_%=;" + + "*(u64 *)(r10 - 16) = r0;" + + "r1 = %[amap] ll;" + "r2 = r10;" + "r2 += -16;" + "call %[bpf_map_lookup_elem];" + "r6 = r0;" + + "r1 = %[amap] ll;" + "r2 = r10;" + "r2 += -16;" + "call %[bpf_map_lookup_elem];" + "r7 = r0;" + + "r1 = %[amap] ll;" + "r2 = r10;" + "r2 += -16;" + "call %[bpf_map_lookup_elem];" + "r8 = r0;" + + "r1 = %[amap] ll;" + "r2 = r10;" + "r2 += -16;" + "call %[bpf_map_lookup_elem];" + "*(u64 *)(r10 - 24) = r0;" + + "r1 = %[amap] ll;" + "r2 = r10;" + "r2 += -16;" + "call %[bpf_map_lookup_elem];" + "*(u64 *)(r10 - 32) = r0;" + + "r1 = %[amap] ll;" + "r2 = r10;" + "r2 += -16;" + "call %[bpf_map_lookup_elem];" + "*(u64 *)(r10 - 40) = r0;" + + "if r6 == 0 goto +1;" + "r9 += 1;" + "if r7 == 0 goto +1;" + "r9 += 1;" + "if r8 == 0 goto +1;" + "r9 += 1;" + "r0 = *(u64 *)(r10 - 24);" + "if r0 == 0 goto +1;" + "r9 += 1;" + "r0 = *(u64 *)(r10 - 32);" + "if r0 == 0 goto +1;" + "r9 += 1;" + "r0 = *(u64 *)(r10 - 40);" + "if r0 == 0 goto +1;" + "r9 += 1;" + + "goto loop_%=;" + "loop_end_%=:" + "r1 = r10;" + "r1 += -8;" + "call %[bpf_iter_num_destroy];" + "r0 = 0;" + "exit;" + : + : __imm(bpf_map_lookup_elem), + __imm(bpf_iter_num_new), + __imm(bpf_iter_num_next), + __imm(bpf_iter_num_destroy), + __imm_addr(amap) + : __clobber_all + ); +} + char _license[] SEC("license") = "GPL"; -- 2.43.0
