diff options
| author | Xu Kuohai <xukuohai@huawei.com> | 2022-07-11 11:08:20 -0400 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2022-07-11 21:04:58 +0200 |
| commit | 535a57a7ffc04932ad83c1a5649b09ba6c93ce83 (patch) | |
| tree | ffc9d4fc14e5a6b489fc1cfa6f5de8001368f164 | |
| parent | 9974d37ea75f01b47d16072b5dad305bd8d23fcc (diff) | |
bpf: Remove is_valid_bpf_tramp_flags()
Before generating bpf trampoline, x86 calls is_valid_bpf_tramp_flags()
to check the input flags. This check is architecture independent.
So, to be consistent with x86, arm64 should also do this check
before generating bpf trampoline.
However, the BPF_TRAMP_F_XXX flags are not used by user code and the
flags argument is almost constant at compile time, so this run time
check is a bit redundant.
Remove is_valid_bpf_tramp_flags() and add some comments to the usage of
BPF_TRAMP_F_XXX flags, as suggested by Alexei.
Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20220711150823.2128542-2-xukuohai@huawei.com
| -rw-r--r-- | arch/x86/net/bpf_jit_comp.c | 20 | ||||
| -rw-r--r-- | kernel/bpf/bpf_struct_ops.c | 3 | ||||
| -rw-r--r-- | kernel/bpf/trampoline.c | 3 |
3 files changed, 6 insertions, 20 deletions
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index b88f43c9f050..d2614f1bf838 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -1936,23 +1936,6 @@ static int invoke_bpf_mod_ret(const struct btf_func_model *m, u8 **pprog, return 0; } -static bool is_valid_bpf_tramp_flags(unsigned int flags) -{ - if ((flags & BPF_TRAMP_F_RESTORE_REGS) && - (flags & BPF_TRAMP_F_SKIP_FRAME)) - return false; - - /* - * BPF_TRAMP_F_RET_FENTRY_RET is only used by bpf_struct_ops, - * and it must be used alone. - */ - if ((flags & BPF_TRAMP_F_RET_FENTRY_RET) && - (flags & ~BPF_TRAMP_F_RET_FENTRY_RET)) - return false; - - return true; -} - /* Example: * __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev); * its 'struct btf_func_model' will be nr_args=2 @@ -2031,9 +2014,6 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i if (nr_args > 6) return -ENOTSUPP; - if (!is_valid_bpf_tramp_flags(flags)) - return -EINVAL; - /* Generated trampoline stack layout: * * RBP + 8 [ return address ] diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c index 7e0068c3399c..84b2d9dba79a 100644 --- a/kernel/bpf/bpf_struct_ops.c +++ b/kernel/bpf/bpf_struct_ops.c @@ -341,6 +341,9 @@ int bpf_struct_ops_prepare_trampoline(struct bpf_tramp_links *tlinks, tlinks[BPF_TRAMP_FENTRY].links[0] = link; tlinks[BPF_TRAMP_FENTRY].nr_links = 1; + /* BPF_TRAMP_F_RET_FENTRY_RET is only used by bpf_struct_ops, + * and it must be used alone. + */ flags = model->ret_size > 0 ? BPF_TRAMP_F_RET_FENTRY_RET : 0; return arch_prepare_bpf_trampoline(NULL, image, image_end, model, flags, tlinks, NULL); diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index 6cd226584c33..fd69812412ca 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -360,6 +360,9 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr) if (tlinks[BPF_TRAMP_FEXIT].nr_links || tlinks[BPF_TRAMP_MODIFY_RETURN].nr_links) + /* NOTE: BPF_TRAMP_F_RESTORE_REGS and BPF_TRAMP_F_SKIP_FRAME + * should not be set together. + */ flags = BPF_TRAMP_F_CALL_ORIG | BPF_TRAMP_F_SKIP_FRAME; if (ip_arg) |