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Merge branch 'two-small-fixes-for-global-subprog-tagging'

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Andrii Nakryiko says:

====================
Two small fixes for global subprog tagging

Fix a bug with passing trusted PTR_TO_BTF_ID_OR_NULL register into global
subprog that expects `__arg_trusted __arg_nullable` arguments, which was
discovered when adopting production BPF application.

Also fix annoying warnings that are irrelevant for static subprogs, which are
just an artifact of using btf_prepare_func_args() for both static and global
subprogs.
====================

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20240202190529.2374377-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Alexei Starovoitov 2024-02-02 18:08:59 -08:00
commit 2a79690eae
3 changed files with 36 additions and 3 deletions
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6
kernel/bpf/btf.c
View File

@ -7122,6 +7122,8 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog)
args = (const struct btf_param *)(t + 1);
nargs = btf_type_vlen(t);
if (nargs > MAX_BPF_FUNC_REG_ARGS) {
if (!is_global)
return -EINVAL;
bpf_log(log, "Global function %s() with %d > %d args. Buggy compiler.\n",
tname, nargs, MAX_BPF_FUNC_REG_ARGS);
return -EINVAL;
@ -7131,6 +7133,8 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog)
while (btf_type_is_modifier(t))
t = btf_type_by_id(btf, t->type);
if (!btf_type_is_int(t) && !btf_is_any_enum(t)) {
if (!is_global)
return -EINVAL;
bpf_log(log,
"Global function %s() doesn't return scalar. Only those are supported.\n",
tname);
@ -7251,6 +7255,8 @@ skip_pointer:
sub->args[i].arg_type = ARG_ANYTHING;
continue;
}
if (!is_global)
return -EINVAL;
bpf_log(log, "Arg#%d type %s in %s() is not supported yet.\n",
i, btf_type_str(t), tname);
return -EINVAL;

1
kernel/bpf/verifier.c
View File

@ -8242,6 +8242,7 @@ found:
switch ((int)reg->type) {
case PTR_TO_BTF_ID:
case PTR_TO_BTF_ID | PTR_TRUSTED:
case PTR_TO_BTF_ID | PTR_TRUSTED | PTR_MAYBE_NULL:
case PTR_TO_BTF_ID | MEM_RCU:
case PTR_TO_BTF_ID | PTR_MAYBE_NULL:
case PTR_TO_BTF_ID | PTR_MAYBE_NULL | MEM_RCU:

32
tools/testing/selftests/bpf/progs/verifier_global_ptr_args.c
View File

@ -19,15 +19,41 @@ __weak int subprog_trusted_task_nullable(struct task_struct *task __arg_trusted
return task->pid + task->tgid;
}
SEC("?kprobe")
__weak int subprog_trusted_task_nullable_extra_layer(struct task_struct *task __arg_trusted __arg_nullable)
{
return subprog_trusted_task_nullable(task) + subprog_trusted_task_nullable(NULL);
}
SEC("?tp_btf/task_newtask")
__success __log_level(2)
__msg("Validating subprog_trusted_task_nullable() func#1...")
__msg(": R1=trusted_ptr_or_null_task_struct(")
int trusted_task_arg_nullable(void *ctx)
{
struct task_struct *t = bpf_get_current_task_btf();
struct task_struct *t1 = bpf_get_current_task_btf();
struct task_struct *t2 = bpf_task_acquire(t1);
int res = 0;
return subprog_trusted_task_nullable(t) + subprog_trusted_task_nullable(NULL);
/* known NULL */
res += subprog_trusted_task_nullable(NULL);
/* known non-NULL */
res += subprog_trusted_task_nullable(t1);
res += subprog_trusted_task_nullable_extra_layer(t1);
/* unknown if NULL or not */
res += subprog_trusted_task_nullable(t2);
res += subprog_trusted_task_nullable_extra_layer(t2);
if (t2) {
/* known non-NULL after explicit NULL check, just in case */
res += subprog_trusted_task_nullable(t2);
res += subprog_trusted_task_nullable_extra_layer(t2);
bpf_task_release(t2);
}
return res;
}
__weak int subprog_trusted_task_nonnull(struct task_struct *task __arg_trusted)