From 6dd7f14080473b655c247863e61b7c34424f0c83 Mon Sep 17 00:00:00 2001 From: Paul Chaignon Date: Wed, 24 Apr 2019 21:51:26 +0200 Subject: selftests/bpf: test cases for pkt/null checks in subprogs The first test case, for pointer null checks, is equivalent to the following pseudo-code. It checks that the verifier does not complain on line 6 and recognizes that ptr isn't null. 1: ptr = bpf_map_lookup_elem(map, &key); 2: ret = subprog(ptr) { 3: return ptr != NULL; 4: } 5: if (ret) 6: value = *ptr; The second test case, for packet bound checks, is equivalent to the following pseudo-code. It checks that the verifier does not complain on line 7 and recognizes that the packet is at least 1 byte long. 1: pkt_end = ctx.pkt_end; 2: ptr = ctx.pkt + 8; 3: ret = subprog(ptr, pkt_end) { 4: return ptr <= pkt_end; 5: } 6: if (ret) 7: value = *(u8 *)ctx.pkt; Signed-off-by: Paul Chaignon Signed-off-by: Alexei Starovoitov --- tools/testing/selftests/bpf/verifier/calls.c | 25 ++++++++++++++++++++++ .../selftests/bpf/verifier/direct_packet_access.c | 22 +++++++++++++++++++ 2 files changed, 47 insertions(+) diff --git a/tools/testing/selftests/bpf/verifier/calls.c b/tools/testing/selftests/bpf/verifier/calls.c index fb11240b758b..9093a8f64dc6 100644 --- a/tools/testing/selftests/bpf/verifier/calls.c +++ b/tools/testing/selftests/bpf/verifier/calls.c @@ -374,6 +374,31 @@ .prog_type = BPF_PROG_TYPE_XDP, .flags = F_NEEDS_EFFICIENT_UNALIGNED_ACCESS, }, +{ + "calls: ptr null check in subprog", + .insns = { + BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0), + BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), + BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8), + BPF_LD_MAP_FD(BPF_REG_1, 0), + BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem), + BPF_MOV64_REG(BPF_REG_1, BPF_REG_0), + BPF_MOV64_REG(BPF_REG_6, BPF_REG_0), + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 1, 0, 3), + BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 1), + BPF_LDX_MEM(BPF_B, BPF_REG_0, BPF_REG_6, 0), + BPF_EXIT_INSN(), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0, 1), + BPF_MOV64_IMM(BPF_REG_0, 1), + BPF_EXIT_INSN(), + }, + .errstr_unpriv = "function calls to other bpf functions are allowed for root only", + .fixup_map_hash_48b = { 3 }, + .result_unpriv = REJECT, + .result = ACCEPT, + .retval = 0, +}, { "calls: two calls with args", .insns = { diff --git a/tools/testing/selftests/bpf/verifier/direct_packet_access.c b/tools/testing/selftests/bpf/verifier/direct_packet_access.c index e3fc22e672c2..d5c596fdc4b9 100644 --- a/tools/testing/selftests/bpf/verifier/direct_packet_access.c +++ b/tools/testing/selftests/bpf/verifier/direct_packet_access.c @@ -631,3 +631,25 @@ .errstr = "invalid access to packet", .prog_type = BPF_PROG_TYPE_SCHED_CLS, }, +{ + "direct packet access: test29 (reg > pkt_end in subprog)", + .insns = { + BPF_LDX_MEM(BPF_W, BPF_REG_6, BPF_REG_1, + offsetof(struct __sk_buff, data)), + BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, + offsetof(struct __sk_buff, data_end)), + BPF_MOV64_REG(BPF_REG_3, BPF_REG_6), + BPF_ALU64_IMM(BPF_ADD, BPF_REG_3, 8), + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 1, 0, 4), + BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 1), + BPF_LDX_MEM(BPF_B, BPF_REG_0, BPF_REG_6, 0), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_JMP_REG(BPF_JGT, BPF_REG_3, BPF_REG_2, 1), + BPF_MOV64_IMM(BPF_REG_0, 1), + BPF_EXIT_INSN(), + }, + .result = ACCEPT, + .prog_type = BPF_PROG_TYPE_SCHED_CLS, +}, -- cgit v1.2.3-58-ga151