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authorAndrii Nakryiko <andrii@kernel.org>2024-08-08 16:22:29 -0700
committerAlexei Starovoitov <ast@kernel.org>2024-08-21 10:37:52 -0700
commitbaebe9aaba1e59e34cd1fe6455bb4c3029ad3bc1 (patch)
tree4f82bb8495a612d772caea6ea667d99fcd94bf31 /kernel/bpf
parent496ddd19a0fad22f250fc7a7b7a8000155418934 (diff)
bpf: allow passing struct bpf_iter_<type> as kfunc arguments
There are potentially useful cases where a specific iterator type might need to be passed into some kfunc. So, in addition to existing bpf_iter_<type>_{new,next,destroy}() kfuncs, allow to pass iterator pointer to any kfunc. We employ "__iter" naming suffix for arguments that are meant to accept iterators. We also enforce that they accept PTR -> STRUCT btf_iter_<type> type chain and point to a valid initialized on-the-stack iterator state. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20240808232230.2848712-3-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel/bpf')
-rw-r--r--kernel/bpf/verifier.c35
1 files changed, 24 insertions, 11 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index df3be12096cf..920d7c5fe944 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -7970,12 +7970,17 @@ static bool is_iter_destroy_kfunc(struct bpf_kfunc_call_arg_meta *meta)
return meta->kfunc_flags & KF_ITER_DESTROY;
}
-static bool is_kfunc_arg_iter(struct bpf_kfunc_call_arg_meta *meta, int arg)
+static bool is_kfunc_arg_iter(struct bpf_kfunc_call_arg_meta *meta, int arg_idx,
+ const struct btf_param *arg)
{
/* btf_check_iter_kfuncs() guarantees that first argument of any iter
* kfunc is iter state pointer
*/
- return arg == 0 && is_iter_kfunc(meta);
+ if (is_iter_kfunc(meta))
+ return arg_idx == 0;
+
+ /* iter passed as an argument to a generic kfunc */
+ return btf_param_match_suffix(meta->btf, arg, "__iter");
}
static int process_iter_arg(struct bpf_verifier_env *env, int regno, int insn_idx,
@@ -7983,14 +7988,20 @@ static int process_iter_arg(struct bpf_verifier_env *env, int regno, int insn_id
{
struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
const struct btf_type *t;
- const struct btf_param *arg;
- int spi, err, i, nr_slots;
- u32 btf_id;
+ int spi, err, i, nr_slots, btf_id;
- /* btf_check_iter_kfuncs() ensures we don't need to validate anything here */
- arg = &btf_params(meta->func_proto)[0];
- t = btf_type_skip_modifiers(meta->btf, arg->type, NULL); /* PTR */
- t = btf_type_skip_modifiers(meta->btf, t->type, &btf_id); /* STRUCT */
+ /* For iter_{new,next,destroy} functions, btf_check_iter_kfuncs()
+ * ensures struct convention, so we wouldn't need to do any BTF
+ * validation here. But given iter state can be passed as a parameter
+ * to any kfunc, if arg has "__iter" suffix, we need to be a bit more
+ * conservative here.
+ */
+ btf_id = btf_check_iter_arg(meta->btf, meta->func_proto, regno - 1);
+ if (btf_id < 0) {
+ verbose(env, "expected valid iter pointer as arg #%d\n", regno);
+ return -EINVAL;
+ }
+ t = btf_type_by_id(meta->btf, btf_id);
nr_slots = t->size / BPF_REG_SIZE;
if (is_iter_new_kfunc(meta)) {
@@ -8012,7 +8023,9 @@ static int process_iter_arg(struct bpf_verifier_env *env, int regno, int insn_id
if (err)
return err;
} else {
- /* iter_next() or iter_destroy() expect initialized iter state*/
+ /* iter_next() or iter_destroy(), as well as any kfunc
+ * accepting iter argument, expect initialized iter state
+ */
err = is_iter_reg_valid_init(env, reg, meta->btf, btf_id, nr_slots);
switch (err) {
case 0:
@@ -11382,7 +11395,7 @@ get_kfunc_ptr_arg_type(struct bpf_verifier_env *env,
if (is_kfunc_arg_dynptr(meta->btf, &args[argno]))
return KF_ARG_PTR_TO_DYNPTR;
- if (is_kfunc_arg_iter(meta, argno))
+ if (is_kfunc_arg_iter(meta, argno, &args[argno]))
return KF_ARG_PTR_TO_ITER;
if (is_kfunc_arg_list_head(meta->btf, &args[argno]))