From: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
Move dynptr type check to is_dynptr_type_expected() from
is_dynptr_reg_valid_init(), so that callers can better determine the cause
of a negative result (dynamic pointer not valid/initialized, dynamic
pointer of the wrong type).
Also, splitting makes the code more readable, since checking the dynamic
pointer type is not necessarily related to validity and initialization.
Split the validity/initialization and dynamic pointer type check also in
the verifier, and adjust the expected error message in the test (a test for
an unexpected dynptr type passed to a helper cannot be added due to missing
suitable helpers, but this case has been tested manually).
Cc: Joanne Koong <joannelkoong@xxxxxxxxx>
Cc: Kumar Kartikeya Dwivedi <memxor@xxxxxxxxx>
Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
---
kernel/bpf/verifier.c | 35 ++++++++++++++-----
.../testing/selftests/bpf/prog_tests/dynptr.c | 2 +-
2 files changed, 28 insertions(+), 9 deletions(-)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 0194a36d0b36..1b913db252a3 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -779,8 +779,8 @@ static bool is_dynptr_reg_valid_uninit(struct bpf_verifier_env *env, struct bpf_
return true;
}
-static bool is_dynptr_reg_valid_init(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
- enum bpf_arg_type arg_type)
+static bool is_dynptr_reg_valid_init(struct bpf_verifier_env *env,
+ struct bpf_reg_state *reg)
{
struct bpf_func_state *state = func(env, reg);
int spi = get_spi(reg->off);
@@ -796,11 +796,24 @@ static bool is_dynptr_reg_valid_init(struct bpf_verifier_env *env, struct bpf_re
return false;
}
+ return true;
+}
+
+static bool is_dynptr_type_expected(struct bpf_verifier_env *env,
+ struct bpf_reg_state *reg,
+ enum bpf_arg_type arg_type)
+{
+ struct bpf_func_state *state = func(env, reg);
+ int spi = get_spi(reg->off);
+ enum bpf_dynptr_type dynptr_type;
+
/* ARG_PTR_TO_DYNPTR takes any type of dynptr */
if (arg_type == ARG_PTR_TO_DYNPTR)
return true;
- return state->stack[spi].spilled_ptr.dynptr.type == arg_to_dynptr_type(arg_type);
+ dynptr_type = arg_to_dynptr_type(arg_type);
+
+ return state->stack[spi].spilled_ptr.dynptr.type == dynptr_type;
}
/* The reg state of a pointer or a bounded scalar was saved when
@@ -6050,21 +6063,27 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
}
meta->uninit_dynptr_regno = regno;
- } else if (!is_dynptr_reg_valid_init(env, reg, arg_type)) {
+ } else if (!is_dynptr_reg_valid_init(env, reg)) {
+ verbose(env,
+ "Expected an initialized dynptr as arg #%d\n",
+ arg + 1);
+ return -EINVAL;
+ } else if (!is_dynptr_type_expected(env, reg, arg_type)) {
const char *err_extra = "";
switch (arg_type & DYNPTR_TYPE_FLAG_MASK) {
case DYNPTR_TYPE_LOCAL:
- err_extra = "local ";
+ err_extra = "local";
break;
case DYNPTR_TYPE_RINGBUF:
- err_extra = "ringbuf ";
+ err_extra = "ringbuf";
break;
default:
+ err_extra = "<unknown>";
break;
}
-
- verbose(env, "Expected an initialized %sdynptr as arg #%d\n",
+ verbose(env,
+ "Expected a dynptr of type %s as arg #%d\n",
err_extra, arg + 1);
return -EINVAL;
}
diff --git a/tools/testing/selftests/bpf/prog_tests/dynptr.c b/tools/testing/selftests/bpf/prog_tests/dynptr.c
index bcf80b9f7c27..8fc4e6c02bfd 100644
--- a/tools/testing/selftests/bpf/prog_tests/dynptr.c
+++ b/tools/testing/selftests/bpf/prog_tests/dynptr.c
@@ -30,7 +30,7 @@ static struct {
{"invalid_helper2", "Expected an initialized dynptr as arg #3"},
{"invalid_write1", "Expected an initialized dynptr as arg #1"},
{"invalid_write2", "Expected an initialized dynptr as arg #3"},
- {"invalid_write3", "Expected an initialized ringbuf dynptr as arg #1"},
+ {"invalid_write3", "Expected an initialized dynptr as arg #1"},
{"invalid_write4", "arg 1 is an unacquired reference"},
{"invalid_read1", "invalid read from stack"},
{"invalid_read2", "cannot pass in dynptr at an offset"},
--
2.25.1
