Add bpf_jit_supports_stack_args() as a weak function defaulting to false. Architectures that implement JIT support for stack arguments override it to return true. Reject BPF functions and kfuncs with more than 5 parameters at verification time if the architecture does not support stack arguments. Acked-by: Puranjay Mohan Signed-off-by: Yonghong Song --- include/linux/filter.h | 1 + kernel/bpf/btf.c | 8 +++++++- kernel/bpf/core.c | 5 +++++ kernel/bpf/verifier.c | 5 +++++ 4 files changed, 18 insertions(+), 1 deletion(-) diff --git a/include/linux/filter.h b/include/linux/filter.h index b77d0b06db6e..911205dd670e 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -1163,6 +1163,7 @@ bool bpf_jit_inlines_helper_call(s32 imm); bool bpf_jit_supports_subprog_tailcalls(void); bool bpf_jit_supports_percpu_insn(void); bool bpf_jit_supports_kfunc_call(void); +bool bpf_jit_supports_stack_args(void); bool bpf_jit_supports_far_kfunc_call(void); bool bpf_jit_supports_exceptions(void); bool bpf_jit_supports_ptr_xchg(void); diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index cfb35a2decf6..fa4b971c5289 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -7890,8 +7890,14 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog) tname, nargs, MAX_BPF_FUNC_REG_ARGS); return -EINVAL; } - if (nargs > MAX_BPF_FUNC_REG_ARGS) + if (nargs > MAX_BPF_FUNC_REG_ARGS) { + if (!bpf_jit_supports_stack_args()) { + bpf_log(log, "JIT does not support function %s() with %d args\n", + tname, nargs); + return -ENOTSUPP; + } sub->incoming_stack_arg_depth = (nargs - MAX_BPF_FUNC_REG_ARGS) * BPF_REG_SIZE; + } /* check that function is void or returns int, exception cb also requires this */ t = btf_type_by_id(btf, t->type); diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index ec8523e6e4eb..7522b3d7b267 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -3217,6 +3217,11 @@ bool __weak bpf_jit_supports_kfunc_call(void) return false; } +bool __weak bpf_jit_supports_stack_args(void) +{ + return false; +} + bool __weak bpf_jit_supports_far_kfunc_call(void) { return false; diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index e041c182c614..0ba140dabe93 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -12254,6 +12254,11 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_ MAX_BPF_FUNC_REG_ARGS); return -EINVAL; } + if (nargs > MAX_BPF_FUNC_REG_ARGS && !bpf_jit_supports_stack_args()) { + verbose(env, "JIT does not support kfunc %s() with %d args\n", + func_name, nargs); + return -ENOTSUPP; + } /* Check that BTF function arguments match actual types that the * verifier sees. -- 2.52.0