diff options
Diffstat (limited to 'tools/testing/selftests/bpf/verifier/jeq_infer_not_null.c')
| -rw-r--r-- | tools/testing/selftests/bpf/verifier/jeq_infer_not_null.c | 174 |
1 files changed, 174 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/verifier/jeq_infer_not_null.c b/tools/testing/selftests/bpf/verifier/jeq_infer_not_null.c new file mode 100644 index 000000000000..67a1c07ead34 --- /dev/null +++ b/tools/testing/selftests/bpf/verifier/jeq_infer_not_null.c @@ -0,0 +1,174 @@ +{ + /* This is equivalent to the following program: + * + * r6 = skb->sk; + * r7 = sk_fullsock(r6); + * r0 = sk_fullsock(r6); + * if (r0 == 0) return 0; (a) + * if (r0 != r7) return 0; (b) + * *r7->type; (c) + * return 0; + * + * It is safe to dereference r7 at point (c), because of (a) and (b). + * The test verifies that relation r0 == r7 is propagated from (b) to (c). + */ + "jne/jeq infer not null, PTR_TO_SOCKET_OR_NULL -> PTR_TO_SOCKET for JNE false branch", + .insns = { + /* r6 = skb->sk; */ + BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1, offsetof(struct __sk_buff, sk)), + /* if (r6 == 0) return 0; */ + BPF_JMP_IMM(BPF_JEQ, BPF_REG_6, 0, 8), + /* r7 = sk_fullsock(skb); */ + BPF_MOV64_REG(BPF_REG_1, BPF_REG_6), + BPF_EMIT_CALL(BPF_FUNC_sk_fullsock), + BPF_MOV64_REG(BPF_REG_7, BPF_REG_0), + /* r0 = sk_fullsock(skb); */ + BPF_MOV64_REG(BPF_REG_1, BPF_REG_6), + BPF_EMIT_CALL(BPF_FUNC_sk_fullsock), + /* if (r0 == null) return 0; */ + BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2), + /* if (r0 == r7) r0 = *(r7->type); */ + BPF_JMP_REG(BPF_JNE, BPF_REG_0, BPF_REG_7, 1), /* Use ! JNE ! */ + BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_7, offsetof(struct bpf_sock, type)), + /* return 0 */ + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }, + .prog_type = BPF_PROG_TYPE_CGROUP_SKB, + .result = ACCEPT, + .result_unpriv = REJECT, + .errstr_unpriv = "R7 pointer comparison", +}, +{ + /* Same as above, but verify that another branch of JNE still + * prohibits access to PTR_MAYBE_NULL. + */ + "jne/jeq infer not null, PTR_TO_SOCKET_OR_NULL unchanged for JNE true branch", + .insns = { + /* r6 = skb->sk */ + BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1, offsetof(struct __sk_buff, sk)), + /* if (r6 == 0) return 0; */ + BPF_JMP_IMM(BPF_JEQ, BPF_REG_6, 0, 9), + /* r7 = sk_fullsock(skb); */ + BPF_MOV64_REG(BPF_REG_1, BPF_REG_6), + BPF_EMIT_CALL(BPF_FUNC_sk_fullsock), + BPF_MOV64_REG(BPF_REG_7, BPF_REG_0), + /* r0 = sk_fullsock(skb); */ + BPF_MOV64_REG(BPF_REG_1, BPF_REG_6), + BPF_EMIT_CALL(BPF_FUNC_sk_fullsock), + /* if (r0 == null) return 0; */ + BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 3), + /* if (r0 == r7) return 0; */ + BPF_JMP_REG(BPF_JNE, BPF_REG_0, BPF_REG_7, 1), /* Use ! JNE ! */ + BPF_JMP_IMM(BPF_JA, 0, 0, 1), + /* r0 = *(r7->type); */ + BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_7, offsetof(struct bpf_sock, type)), + /* return 0 */ + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }, + .prog_type = BPF_PROG_TYPE_CGROUP_SKB, + .result = REJECT, + .errstr = "R7 invalid mem access 'sock_or_null'", + .result_unpriv = REJECT, + .errstr_unpriv = "R7 pointer comparison", +}, +{ + /* Same as a first test, but not null should be inferred for JEQ branch */ + "jne/jeq infer not null, PTR_TO_SOCKET_OR_NULL -> PTR_TO_SOCKET for JEQ true branch", + .insns = { + /* r6 = skb->sk; */ + BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1, offsetof(struct __sk_buff, sk)), + /* if (r6 == null) return 0; */ + BPF_JMP_IMM(BPF_JEQ, BPF_REG_6, 0, 9), + /* r7 = sk_fullsock(skb); */ + BPF_MOV64_REG(BPF_REG_1, BPF_REG_6), + BPF_EMIT_CALL(BPF_FUNC_sk_fullsock), + BPF_MOV64_REG(BPF_REG_7, BPF_REG_0), + /* r0 = sk_fullsock(skb); */ + BPF_MOV64_REG(BPF_REG_1, BPF_REG_6), + BPF_EMIT_CALL(BPF_FUNC_sk_fullsock), + /* if (r0 == null) return 0; */ + BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 3), + /* if (r0 != r7) return 0; */ + BPF_JMP_REG(BPF_JEQ, BPF_REG_0, BPF_REG_7, 1), /* Use ! JEQ ! */ + BPF_JMP_IMM(BPF_JA, 0, 0, 1), + /* r0 = *(r7->type); */ + BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_7, offsetof(struct bpf_sock, type)), + /* return 0; */ + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }, + .prog_type = BPF_PROG_TYPE_CGROUP_SKB, + .result = ACCEPT, + .result_unpriv = REJECT, + .errstr_unpriv = "R7 pointer comparison", +}, +{ + /* Same as above, but verify that another branch of JNE still + * prohibits access to PTR_MAYBE_NULL. + */ + "jne/jeq infer not null, PTR_TO_SOCKET_OR_NULL unchanged for JEQ false branch", + .insns = { + /* r6 = skb->sk; */ + BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1, offsetof(struct __sk_buff, sk)), + /* if (r6 == null) return 0; */ + BPF_JMP_IMM(BPF_JEQ, BPF_REG_6, 0, 8), + /* r7 = sk_fullsock(skb); */ + BPF_MOV64_REG(BPF_REG_1, BPF_REG_6), + BPF_EMIT_CALL(BPF_FUNC_sk_fullsock), + BPF_MOV64_REG(BPF_REG_7, BPF_REG_0), + /* r0 = sk_fullsock(skb); */ + BPF_MOV64_REG(BPF_REG_1, BPF_REG_6), + BPF_EMIT_CALL(BPF_FUNC_sk_fullsock), + /* if (r0 == null) return 0; */ + BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2), + /* if (r0 != r7) r0 = *(r7->type); */ + BPF_JMP_REG(BPF_JEQ, BPF_REG_0, BPF_REG_7, 1), /* Use ! JEQ ! */ + BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_7, offsetof(struct bpf_sock, type)), + /* return 0; */ + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }, + .prog_type = BPF_PROG_TYPE_CGROUP_SKB, + .result = REJECT, + .errstr = "R7 invalid mem access 'sock_or_null'", + .result_unpriv = REJECT, + .errstr_unpriv = "R7 pointer comparison", +}, +{ + /* Maps are treated in a different branch of `mark_ptr_not_null_reg`, + * so separate test for maps case. + */ + "jne/jeq infer not null, PTR_TO_MAP_VALUE_OR_NULL -> PTR_TO_MAP_VALUE", + .insns = { + /* r9 = &some stack to use as key */ + BPF_ST_MEM(BPF_W, BPF_REG_10, -8, 0), + BPF_MOV64_REG(BPF_REG_9, BPF_REG_10), + BPF_ALU64_IMM(BPF_ADD, BPF_REG_9, -8), + /* r8 = process local map */ + BPF_LD_MAP_FD(BPF_REG_8, 0), + /* r6 = map_lookup_elem(r8, r9); */ + BPF_MOV64_REG(BPF_REG_1, BPF_REG_8), + BPF_MOV64_REG(BPF_REG_2, BPF_REG_9), + BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem), + BPF_MOV64_REG(BPF_REG_6, BPF_REG_0), + /* r7 = map_lookup_elem(r8, r9); */ + BPF_MOV64_REG(BPF_REG_1, BPF_REG_8), + BPF_MOV64_REG(BPF_REG_2, BPF_REG_9), + BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem), + BPF_MOV64_REG(BPF_REG_7, BPF_REG_0), + /* if (r6 == 0) return 0; */ + BPF_JMP_IMM(BPF_JEQ, BPF_REG_6, 0, 2), + /* if (r6 != r7) return 0; */ + BPF_JMP_REG(BPF_JNE, BPF_REG_6, BPF_REG_7, 1), + /* read *r7; */ + BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_7, offsetof(struct bpf_xdp_sock, queue_id)), + /* return 0; */ + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }, + .fixup_map_xskmap = { 3 }, + .prog_type = BPF_PROG_TYPE_XDP, + .result = ACCEPT, +}, |