From 8aa2d4b4b92cd534d53353b0c2fb079572b97fdf Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Mon, 1 Apr 2019 21:27:49 -0700 Subject: [PATCH] selftests/bpf: synthetic tests to push verifier limits Add a test to generate 1m ld_imm64 insns to stress the verifier. Bump the size of fill_ld_abs_vlan_push_pop test from 4k to 29k and jump_around_ld_abs from 4k to 5.5k. Larger sizes are not possible due to 16-bit offset encoding in jump instructions. Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann --- tools/testing/selftests/bpf/test_verifier.c | 35 +++++++++++++++----- tools/testing/selftests/bpf/verifier/ld_dw.c | 9 +++++ 2 files changed, 35 insertions(+), 9 deletions(-) diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c index 19b5d03acc2a..75ef63b42f2c 100644 --- a/tools/testing/selftests/bpf/test_verifier.c +++ b/tools/testing/selftests/bpf/test_verifier.c @@ -50,6 +50,7 @@ #include "../../../include/linux/filter.h" #define MAX_INSNS BPF_MAXINSNS +#define MAX_TEST_INSNS 1000000 #define MAX_FIXUPS 8 #define MAX_NR_MAPS 14 #define MAX_TEST_RUNS 8 @@ -66,6 +67,7 @@ static int skips; struct bpf_test { const char *descr; struct bpf_insn insns[MAX_INSNS]; + struct bpf_insn *fill_insns; int fixup_map_hash_8b[MAX_FIXUPS]; int fixup_map_hash_48b[MAX_FIXUPS]; int fixup_map_hash_16b[MAX_FIXUPS]; @@ -83,6 +85,7 @@ struct bpf_test { const char *errstr; const char *errstr_unpriv; uint32_t retval, retval_unpriv, insn_processed; + int prog_len; enum { UNDEF, ACCEPT, @@ -119,10 +122,11 @@ struct other_val { static void bpf_fill_ld_abs_vlan_push_pop(struct bpf_test *self) { - /* test: {skb->data[0], vlan_push} x 68 + {skb->data[0], vlan_pop} x 68 */ + /* test: {skb->data[0], vlan_push} x 51 + {skb->data[0], vlan_pop} x 51 */ #define PUSH_CNT 51 - unsigned int len = BPF_MAXINSNS; - struct bpf_insn *insn = self->insns; + /* jump range is limited to 16 bit. PUSH_CNT of ld_abs needs room */ + unsigned int len = (1 << 15) - PUSH_CNT * 2 * 5 * 6; + struct bpf_insn *insn = self->fill_insns; int i = 0, j, k = 0; insn[i++] = BPF_MOV64_REG(BPF_REG_6, BPF_REG_1); @@ -156,12 +160,14 @@ loop: for (; i < len - 1; i++) insn[i] = BPF_ALU32_IMM(BPF_MOV, BPF_REG_0, 0xbef); insn[len - 1] = BPF_EXIT_INSN(); + self->prog_len = len; } static void bpf_fill_jump_around_ld_abs(struct bpf_test *self) { - struct bpf_insn *insn = self->insns; - unsigned int len = BPF_MAXINSNS; + struct bpf_insn *insn = self->fill_insns; + /* jump range is limited to 16 bit. every ld_abs is replaced by 6 insns */ + unsigned int len = (1 << 15) / 6; int i = 0; insn[i++] = BPF_MOV64_REG(BPF_REG_6, BPF_REG_1); @@ -171,11 +177,12 @@ static void bpf_fill_jump_around_ld_abs(struct bpf_test *self) while (i < len - 1) insn[i++] = BPF_LD_ABS(BPF_B, 1); insn[i] = BPF_EXIT_INSN(); + self->prog_len = i + 1; } static void bpf_fill_rand_ld_dw(struct bpf_test *self) { - struct bpf_insn *insn = self->insns; + struct bpf_insn *insn = self->fill_insns; uint64_t res = 0; int i = 0; @@ -193,6 +200,7 @@ static void bpf_fill_rand_ld_dw(struct bpf_test *self) insn[i++] = BPF_ALU64_IMM(BPF_RSH, BPF_REG_1, 32); insn[i++] = BPF_ALU64_REG(BPF_XOR, BPF_REG_0, BPF_REG_1); insn[i] = BPF_EXIT_INSN(); + self->prog_len = i + 1; res ^= (res >> 32); self->retval = (uint32_t)res; } @@ -520,8 +528,10 @@ static void do_test_fixup(struct bpf_test *test, enum bpf_prog_type prog_type, int *fixup_percpu_cgroup_storage = test->fixup_percpu_cgroup_storage; int *fixup_map_spin_lock = test->fixup_map_spin_lock; - if (test->fill_helper) + if (test->fill_helper) { + test->fill_insns = calloc(MAX_TEST_INSNS, sizeof(struct bpf_insn)); test->fill_helper(test); + } /* Allocating HTs with 1 elem is fine here, since we only test * for verifier and not do a runtime lookup, so the only thing @@ -718,12 +728,17 @@ static void do_test_single(struct bpf_test *test, bool unpriv, prog_type = BPF_PROG_TYPE_SOCKET_FILTER; fixup_skips = skips; do_test_fixup(test, prog_type, prog, map_fds); + if (test->fill_insns) { + prog = test->fill_insns; + prog_len = test->prog_len; + } else { + prog_len = probe_filter_length(prog); + } /* If there were some map skips during fixup due to missing bpf * features, skip this test. */ if (fixup_skips != skips) return; - prog_len = probe_filter_length(prog); pflags = 0; if (test->flags & F_LOAD_WITH_STRICT_ALIGNMENT) @@ -731,7 +746,7 @@ static void do_test_single(struct bpf_test *test, bool unpriv, if (test->flags & F_NEEDS_EFFICIENT_UNALIGNED_ACCESS) pflags |= BPF_F_ANY_ALIGNMENT; fd_prog = bpf_verify_program(prog_type, prog, prog_len, pflags, - "GPL", 0, bpf_vlog, sizeof(bpf_vlog), 1); + "GPL", 0, bpf_vlog, sizeof(bpf_vlog), 4); if (fd_prog < 0 && !bpf_probe_prog_type(prog_type, 0)) { printf("SKIP (unsupported program type %d)\n", prog_type); skips++; @@ -830,6 +845,8 @@ static void do_test_single(struct bpf_test *test, bool unpriv, goto fail_log; } close_fds: + if (test->fill_insns) + free(test->fill_insns); close(fd_prog); for (i = 0; i < MAX_NR_MAPS; i++) close(map_fds[i]); diff --git a/tools/testing/selftests/bpf/verifier/ld_dw.c b/tools/testing/selftests/bpf/verifier/ld_dw.c index d2c75b889598..0f18e62f0099 100644 --- a/tools/testing/selftests/bpf/verifier/ld_dw.c +++ b/tools/testing/selftests/bpf/verifier/ld_dw.c @@ -34,3 +34,12 @@ .result = ACCEPT, .retval = 5, }, +{ + "ld_dw: xor semi-random 64 bit imms, test 5", + .insns = { }, + .data = { }, + .fill_helper = bpf_fill_rand_ld_dw, + .prog_type = BPF_PROG_TYPE_SCHED_CLS, + .result = ACCEPT, + .retval = 1000000 - 6, +},