selftests/bpf: Add tests for kfunc register offset checks

Include a few verifier selftests that test against the problems being
fixed by previous commits, i.e. release kfunc always require
PTR_TO_BTF_ID fixed and var_off to be 0, and negative offset is not
permitted and returns a helpful error message.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220304224645.3677453-9-memxor@gmail.com

diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index fcc8301..ba410b0 100644 (file)
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -270,9 +270,14 @@ struct sock * noinline bpf_kfunc_call_test3(struct sock *sk)
        return sk;
 }
 
+struct prog_test_member {
+       u64 c;
+};
+
 struct prog_test_ref_kfunc {
        int a;
        int b;
+       struct prog_test_member memb;
        struct prog_test_ref_kfunc *next;
 };
 
@@ -295,6 +300,10 @@ noinline void bpf_kfunc_call_test_release(struct prog_test_ref_kfunc *p)
 {
 }
 
+noinline void bpf_kfunc_call_memb_release(struct prog_test_member *p)
+{
+}
+
 struct prog_test_pass1 {
        int x0;
        struct {
@@ -379,6 +388,7 @@ BTF_ID(func, bpf_kfunc_call_test2)
 BTF_ID(func, bpf_kfunc_call_test3)
 BTF_ID(func, bpf_kfunc_call_test_acquire)
 BTF_ID(func, bpf_kfunc_call_test_release)
+BTF_ID(func, bpf_kfunc_call_memb_release)
 BTF_ID(func, bpf_kfunc_call_test_pass_ctx)
 BTF_ID(func, bpf_kfunc_call_test_pass1)
 BTF_ID(func, bpf_kfunc_call_test_pass2)
@@ -396,6 +406,7 @@ BTF_SET_END(test_sk_acquire_kfunc_ids)
 
 BTF_SET_START(test_sk_release_kfunc_ids)
 BTF_ID(func, bpf_kfunc_call_test_release)
+BTF_ID(func, bpf_kfunc_call_memb_release)
 BTF_SET_END(test_sk_release_kfunc_ids)
 
 BTF_SET_START(test_sk_ret_null_kfunc_ids)

diff --git a/tools/testing/selftests/bpf/verifier/calls.c b/tools/testing/selftests/bpf/verifier/calls.c
index f890333..2e03dec 100644 (file)
--- a/tools/testing/selftests/bpf/verifier/calls.c
+++ b/tools/testing/selftests/bpf/verifier/calls.c
@@ -115,6 +115,89 @@
                { "bpf_kfunc_call_test_release", 5 },
        },
 },
+{
+       "calls: invalid kfunc call: reg->off must be zero when passed to release kfunc",
+       .insns = {
+       BPF_MOV64_REG(BPF_REG_1, BPF_REG_10),
+       BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -8),
+       BPF_ST_MEM(BPF_DW, BPF_REG_1, 0, 0),
+       BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0),
+       BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 1),
+       BPF_EXIT_INSN(),
+       BPF_ALU64_IMM(BPF_ADD, BPF_REG_0, 8),
+       BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+       BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0),
+       BPF_MOV64_IMM(BPF_REG_0, 0),
+       BPF_EXIT_INSN(),
+       },
+       .prog_type = BPF_PROG_TYPE_SCHED_CLS,
+       .result = REJECT,
+       .errstr = "R1 must have zero offset when passed to release func",
+       .fixup_kfunc_btf_id = {
+               { "bpf_kfunc_call_test_acquire", 3 },
+               { "bpf_kfunc_call_memb_release", 8 },
+       },
+},
+{
+       "calls: invalid kfunc call: PTR_TO_BTF_ID with negative offset",
+       .insns = {
+       BPF_MOV64_REG(BPF_REG_1, BPF_REG_10),
+       BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -8),
+       BPF_ST_MEM(BPF_DW, BPF_REG_1, 0, 0),
+       BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0),
+       BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 1),
+       BPF_EXIT_INSN(),
+       BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+       BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_1, 16),
+       BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -4),
+       BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0),
+       BPF_MOV64_IMM(BPF_REG_0, 0),
+       BPF_EXIT_INSN(),
+       },
+       .prog_type = BPF_PROG_TYPE_SCHED_CLS,
+       .fixup_kfunc_btf_id = {
+               { "bpf_kfunc_call_test_acquire", 3 },
+               { "bpf_kfunc_call_test_release", 9 },
+       },
+       .result_unpriv = REJECT,
+       .result = REJECT,
+       .errstr = "negative offset ptr_ ptr R1 off=-4 disallowed",
+},
+{
+       "calls: invalid kfunc call: PTR_TO_BTF_ID with variable offset",
+       .insns = {
+       BPF_MOV64_REG(BPF_REG_1, BPF_REG_10),
+       BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -8),
+       BPF_ST_MEM(BPF_DW, BPF_REG_1, 0, 0),
+       BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0),
+       BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 1),
+       BPF_EXIT_INSN(),
+       BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+       BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_0, 4),
+       BPF_JMP_IMM(BPF_JLE, BPF_REG_2, 4, 3),
+       BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0),
+       BPF_MOV64_IMM(BPF_REG_0, 0),
+       BPF_EXIT_INSN(),
+       BPF_JMP_IMM(BPF_JGE, BPF_REG_2, 0, 3),
+       BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0),
+       BPF_MOV64_IMM(BPF_REG_0, 0),
+       BPF_EXIT_INSN(),
+       BPF_ALU64_REG(BPF_ADD, BPF_REG_1, BPF_REG_2),
+       BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0),
+       BPF_MOV64_IMM(BPF_REG_0, 0),
+       BPF_EXIT_INSN(),
+       },
+       .prog_type = BPF_PROG_TYPE_SCHED_CLS,
+       .fixup_kfunc_btf_id = {
+               { "bpf_kfunc_call_test_acquire", 3 },
+               { "bpf_kfunc_call_test_release", 9 },
+               { "bpf_kfunc_call_test_release", 13 },
+               { "bpf_kfunc_call_test_release", 17 },
+       },
+       .result_unpriv = REJECT,
+       .result = REJECT,
+       .errstr = "variable ptr_ access var_off=(0x0; 0x7) disallowed",
+},
 {
        "calls: basic sanity",
        .insns = {