bpf: add additional verifier tests for BPF_PROG_TYPE_LWT_*

- direct packet read is allowed for LWT_*
 - direct packet write for LWT_IN/LWT_OUT is prohibited
 - direct packet write for LWT_XMIT is allowed
 - access to skb->tc_classid is prohibited for LWT_*

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
index 8d71e44..0103bf2 100644 (file)
--- a/tools/testing/selftests/bpf/test_verifier.c
+++ b/tools/testing/selftests/bpf/test_verifier.c
@@ -2743,6 +2743,140 @@ static struct bpf_test tests[] = {
                .result = REJECT,
                .prog_type = BPF_PROG_TYPE_TRACEPOINT,
        },
+       {
+               "invalid direct packet write for LWT_IN",
+               .insns = {
+                       BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
+                                   offsetof(struct __sk_buff, data)),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1,
+                                   offsetof(struct __sk_buff, data_end)),
+                       BPF_MOV64_REG(BPF_REG_0, BPF_REG_2),
+                       BPF_ALU64_IMM(BPF_ADD, BPF_REG_0, 8),
+                       BPF_JMP_REG(BPF_JGT, BPF_REG_0, BPF_REG_3, 1),
+                       BPF_STX_MEM(BPF_B, BPF_REG_2, BPF_REG_2, 0),
+                       BPF_MOV64_IMM(BPF_REG_0, 0),
+                       BPF_EXIT_INSN(),
+               },
+               .errstr = "cannot write into packet",
+               .result = REJECT,
+               .prog_type = BPF_PROG_TYPE_LWT_IN,
+       },
+       {
+               "invalid direct packet write for LWT_OUT",
+               .insns = {
+                       BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
+                                   offsetof(struct __sk_buff, data)),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1,
+                                   offsetof(struct __sk_buff, data_end)),
+                       BPF_MOV64_REG(BPF_REG_0, BPF_REG_2),
+                       BPF_ALU64_IMM(BPF_ADD, BPF_REG_0, 8),
+                       BPF_JMP_REG(BPF_JGT, BPF_REG_0, BPF_REG_3, 1),
+                       BPF_STX_MEM(BPF_B, BPF_REG_2, BPF_REG_2, 0),
+                       BPF_MOV64_IMM(BPF_REG_0, 0),
+                       BPF_EXIT_INSN(),
+               },
+               .errstr = "cannot write into packet",
+               .result = REJECT,
+               .prog_type = BPF_PROG_TYPE_LWT_OUT,
+       },
+       {
+               "direct packet write for LWT_XMIT",
+               .insns = {
+                       BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
+                                   offsetof(struct __sk_buff, data)),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1,
+                                   offsetof(struct __sk_buff, data_end)),
+                       BPF_MOV64_REG(BPF_REG_0, BPF_REG_2),
+                       BPF_ALU64_IMM(BPF_ADD, BPF_REG_0, 8),
+                       BPF_JMP_REG(BPF_JGT, BPF_REG_0, BPF_REG_3, 1),
+                       BPF_STX_MEM(BPF_B, BPF_REG_2, BPF_REG_2, 0),
+                       BPF_MOV64_IMM(BPF_REG_0, 0),
+                       BPF_EXIT_INSN(),
+               },
+               .result = ACCEPT,
+               .prog_type = BPF_PROG_TYPE_LWT_XMIT,
+       },
+       {
+               "direct packet read for LWT_IN",
+               .insns = {
+                       BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
+                                   offsetof(struct __sk_buff, data)),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1,
+                                   offsetof(struct __sk_buff, data_end)),
+                       BPF_MOV64_REG(BPF_REG_0, BPF_REG_2),
+                       BPF_ALU64_IMM(BPF_ADD, BPF_REG_0, 8),
+                       BPF_JMP_REG(BPF_JGT, BPF_REG_0, BPF_REG_3, 1),
+                       BPF_LDX_MEM(BPF_B, BPF_REG_0, BPF_REG_2, 0),
+                       BPF_MOV64_IMM(BPF_REG_0, 0),
+                       BPF_EXIT_INSN(),
+               },
+               .result = ACCEPT,
+               .prog_type = BPF_PROG_TYPE_LWT_IN,
+       },
+       {
+               "direct packet read for LWT_OUT",
+               .insns = {
+                       BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
+                                   offsetof(struct __sk_buff, data)),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1,
+                                   offsetof(struct __sk_buff, data_end)),
+                       BPF_MOV64_REG(BPF_REG_0, BPF_REG_2),
+                       BPF_ALU64_IMM(BPF_ADD, BPF_REG_0, 8),
+                       BPF_JMP_REG(BPF_JGT, BPF_REG_0, BPF_REG_3, 1),
+                       BPF_LDX_MEM(BPF_B, BPF_REG_0, BPF_REG_2, 0),
+                       BPF_MOV64_IMM(BPF_REG_0, 0),
+                       BPF_EXIT_INSN(),
+               },
+               .result = ACCEPT,
+               .prog_type = BPF_PROG_TYPE_LWT_OUT,
+       },
+       {
+               "direct packet read for LWT_XMIT",
+               .insns = {
+                       BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
+                                   offsetof(struct __sk_buff, data)),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1,
+                                   offsetof(struct __sk_buff, data_end)),
+                       BPF_MOV64_REG(BPF_REG_0, BPF_REG_2),
+                       BPF_ALU64_IMM(BPF_ADD, BPF_REG_0, 8),
+                       BPF_JMP_REG(BPF_JGT, BPF_REG_0, BPF_REG_3, 1),
+                       BPF_LDX_MEM(BPF_B, BPF_REG_0, BPF_REG_2, 0),
+                       BPF_MOV64_IMM(BPF_REG_0, 0),
+                       BPF_EXIT_INSN(),
+               },
+               .result = ACCEPT,
+               .prog_type = BPF_PROG_TYPE_LWT_XMIT,
+       },
+       {
+               "invalid access of tc_classid for LWT_IN",
+               .insns = {
+                       BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,
+                                   offsetof(struct __sk_buff, tc_classid)),
+                       BPF_EXIT_INSN(),
+               },
+               .result = REJECT,
+               .errstr = "invalid bpf_context access",
+       },
+       {
+               "invalid access of tc_classid for LWT_OUT",
+               .insns = {
+                       BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,
+                                   offsetof(struct __sk_buff, tc_classid)),
+                       BPF_EXIT_INSN(),
+               },
+               .result = REJECT,
+               .errstr = "invalid bpf_context access",
+       },
+       {
+               "invalid access of tc_classid for LWT_XMIT",
+               .insns = {
+                       BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,
+                                   offsetof(struct __sk_buff, tc_classid)),
+                       BPF_EXIT_INSN(),
+               },
+               .result = REJECT,
+               .errstr = "invalid bpf_context access",
+       },
 };
 
 static int probe_filter_length(const struct bpf_insn *fp)