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bpf: Search and add kfuncs in struct_ops prologue and epilogue

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Currently, add_kfunc_call() is only invoked once before the main
verification loop. Therefore, the verifier could not find the
bpf_kfunc_btf_tab of a new kfunc call which is not seen in user defined
struct_ops operators but introduced in gen_prologue or gen_epilogue
during do_misc_fixup(). Fix this by searching kfuncs in the patching
instruction buffer and add them to prog->aux->kfunc_tab.

Signed-off-by: Amery Hung <amery.hung@bytedance.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20250225233545.285481-1-ameryhung@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Amery Hung 2025-02-25 15:35:44 -08:00 committed by Alexei Starovoitov
parent f3c2d243a3
commit d519594ee2
1 changed files with 24 additions and 1 deletions
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25
kernel/bpf/verifier.c
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@ -3275,6 +3275,21 @@ bpf_jit_find_kfunc_model(const struct bpf_prog *prog,
return res ? &res->func_model : NULL;
}
static int add_kfunc_in_insns(struct bpf_verifier_env *env,
struct bpf_insn *insn, int cnt)
{
int i, ret;
for (i = 0; i < cnt; i++, insn++) {
if (bpf_pseudo_kfunc_call(insn)) {
ret = add_kfunc_call(env, insn->imm, insn->off);
if (ret < 0)
return ret;
}
}
return 0;
}
static int add_subprog_and_kfunc(struct bpf_verifier_env *env)
{
struct bpf_subprog_info *subprog = env->subprog_info;
@ -20433,7 +20448,7 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
{
struct bpf_subprog_info *subprogs = env->subprog_info;
const struct bpf_verifier_ops *ops = env->ops;
int i, cnt, size, ctx_field_size, delta = 0, epilogue_cnt = 0;
int i, cnt, size, ctx_field_size, ret, delta = 0, epilogue_cnt = 0;
const int insn_cnt = env->prog->len;
struct bpf_insn *epilogue_buf = env->epilogue_buf;
struct bpf_insn *insn_buf = env->insn_buf;
@ -20462,6 +20477,10 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
return -ENOMEM;
env->prog = new_prog;
delta += cnt - 1;
ret = add_kfunc_in_insns(env, epilogue_buf, epilogue_cnt - 1);
if (ret < 0)
return ret;
}
}
@ -20482,6 +20501,10 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
env->prog = new_prog;
delta += cnt - 1;
ret = add_kfunc_in_insns(env, insn_buf, cnt - 1);
if (ret < 0)
return ret;
}
}