{ /* 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, },