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Date: Thu, 6 Apr 2023 18:36:38 -0700
From: Alexei Starovoitov <alexei.starovoitov@...il.com>
To: Florian Westphal <fw@...len.de>
Cc: netdev@...r.kernel.org, netfilter-devel@...r.kernel.org,
bpf@...r.kernel.org, dxu@...uu.xyz, qde@...cy.de
Subject: Re: [PATCH bpf-next 6/6] bpf: add test_run support for netfilter
program type
On Wed, Apr 05, 2023 at 06:11:16PM +0200, Florian Westphal wrote:
> also add two simple retval tests: as-is, a return value other
> than accept or drop will cause issues.
>
> NF_QUEUE could be implemented later IFF we can guarantee that
> attachment of such programs can be rejected if they get attached
> to a pf/hook that doesn't support async reinjection.
>
> NF_STOLEN could be implemented via trusted helpers that will eventually
> free the skb, else this would leak the skb reference.
>
> Signed-off-by: Florian Westphal <fw@...len.de>
> ---
> include/linux/bpf.h | 3 +
> net/bpf/test_run.c | 143 ++++++++++++++++++
> net/netfilter/nf_bpf_link.c | 1 +
> .../selftests/bpf/verifier/netfilter.c | 23 +++
> 4 files changed, 170 insertions(+)
> create mode 100644 tools/testing/selftests/bpf/verifier/netfilter.c
>
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index 2d8f3f639e68..453cee1efdd3 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -2235,6 +2235,9 @@ int bpf_prog_test_run_raw_tp(struct bpf_prog *prog,
> int bpf_prog_test_run_sk_lookup(struct bpf_prog *prog,
> const union bpf_attr *kattr,
> union bpf_attr __user *uattr);
> +int bpf_prog_test_run_nf(struct bpf_prog *prog,
> + const union bpf_attr *kattr,
> + union bpf_attr __user *uattr);
> bool btf_ctx_access(int off, int size, enum bpf_access_type type,
> const struct bpf_prog *prog,
> struct bpf_insn_access_aux *info);
> diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
> index f1652f5fbd2e..c14f577fd987 100644
> --- a/net/bpf/test_run.c
> +++ b/net/bpf/test_run.c
> @@ -19,7 +19,9 @@
> #include <linux/error-injection.h>
> #include <linux/smp.h>
> #include <linux/sock_diag.h>
> +#include <linux/netfilter.h>
> #include <net/xdp.h>
> +#include <net/netfilter/nf_bpf_link.h>
>
> #define CREATE_TRACE_POINTS
> #include <trace/events/bpf_test_run.h>
> @@ -1690,6 +1692,147 @@ int bpf_prog_test_run_syscall(struct bpf_prog *prog,
> return err;
> }
>
> +static int verify_and_copy_hook_state(struct nf_hook_state *state,
> + const struct nf_hook_state *user,
> + struct net_device *dev)
> +{
> + if (user->in || user->out)
> + return -EINVAL;
> +
> + if (user->net || user->sk || user->okfn)
> + return -EINVAL;
> +
> + switch (user->pf) {
> + case NFPROTO_IPV4:
> + case NFPROTO_IPV6:
> + switch (state->hook) {
> + case NF_INET_PRE_ROUTING:
> + state->in = dev;
> + break;
> + case NF_INET_LOCAL_IN:
> + state->in = dev;
> + break;
> + case NF_INET_FORWARD:
> + state->in = dev;
> + state->out = dev;
> + break;
> + case NF_INET_LOCAL_OUT:
> + state->out = dev;
> + break;
> + case NF_INET_POST_ROUTING:
> + state->out = dev;
> + break;
> + }
> +
> + break;
> + default:
> + return -EINVAL;
> + }
> +
> + state->pf = user->pf;
> + state->hook = user->hook;
> +
> + return 0;
> +}
> +
> +int bpf_prog_test_run_nf(struct bpf_prog *prog,
> + const union bpf_attr *kattr,
> + union bpf_attr __user *uattr)
> +{
> + struct net *net = current->nsproxy->net_ns;
> + struct net_device *dev = net->loopback_dev;
> + struct nf_hook_state *user_ctx, hook_state = {
> + .pf = NFPROTO_IPV4,
> + .hook = NF_INET_PRE_ROUTING,
> + };
> + u32 size = kattr->test.data_size_in;
> + u32 repeat = kattr->test.repeat;
> + const struct ethhdr *eth;
> + struct bpf_nf_ctx ctx = {
> + .state = &hook_state,
> + };
> + struct sk_buff *skb = NULL;
> + u32 retval, duration;
> + void *data;
> + int ret;
> +
> + if (kattr->test.flags || kattr->test.cpu || kattr->test.batch_size)
> + return -EINVAL;
> +
> + if (size < ETH_HLEN + sizeof(struct iphdr))
> + return -EINVAL;
> +
> + data = bpf_test_init(kattr, kattr->test.data_size_in, size,
> + NET_SKB_PAD + NET_IP_ALIGN,
> + SKB_DATA_ALIGN(sizeof(struct skb_shared_info)));
> + if (IS_ERR(data))
> + return PTR_ERR(data);
> +
> + eth = (struct ethhdr *)data;
> +
> + if (!repeat)
> + repeat = 1;
> +
> + user_ctx = bpf_ctx_init(kattr, sizeof(struct nf_hook_state));
> + if (IS_ERR(user_ctx)) {
> + kfree(data);
> + return PTR_ERR(user_ctx);
> + }
> +
> + if (user_ctx) {
> + ret = verify_and_copy_hook_state(&hook_state, user_ctx, dev);
> + if (ret)
> + goto out;
> + }
> +
> + skb = slab_build_skb(data);
> + if (!skb) {
> + ret = -ENOMEM;
> + goto out;
> + }
> +
> + data = NULL; /* data released via kfree_skb */
> +
> + skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN);
> + __skb_put(skb, size);
> +
> + skb->protocol = eth_type_trans(skb, dev);
> +
> + skb_reset_network_header(skb);
> +
> + ret = -EINVAL;
> +
> + switch (skb->protocol) {
> + case htons(ETH_P_IP):
> + if (hook_state.pf == NFPROTO_IPV4)
> + break;
> + goto out;
> + case htons(ETH_P_IPV6):
> + if (size < ETH_HLEN + sizeof(struct ipv6hdr))
> + goto out;
> + if (hook_state.pf == NFPROTO_IPV6)
> + break;
> + goto out;
> + default:
> + ret = -EPROTO;
> + goto out;
> + }
> +
> + ctx.skb = skb;
> +
> + ret = bpf_test_run(prog, &ctx, repeat, &retval, &duration, false);
> + if (ret)
> + goto out;
> +
> + ret = bpf_test_finish(kattr, uattr, NULL, NULL, 0, retval, duration);
> +
> +out:
> + kfree(user_ctx);
> + kfree_skb(skb);
> + kfree(data);
> + return ret;
> +}
> +
> static const struct btf_kfunc_id_set bpf_prog_test_kfunc_set = {
> .owner = THIS_MODULE,
> .set = &test_sk_check_kfunc_ids,
> diff --git a/net/netfilter/nf_bpf_link.c b/net/netfilter/nf_bpf_link.c
> index 4b22a31d6df5..c27fd569adf1 100644
> --- a/net/netfilter/nf_bpf_link.c
> +++ b/net/netfilter/nf_bpf_link.c
> @@ -128,6 +128,7 @@ int bpf_nf_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
> }
>
> const struct bpf_prog_ops netfilter_prog_ops = {
> + .test_run = bpf_prog_test_run_nf,
> };
>
> static bool nf_ptr_to_btf_id(struct bpf_insn_access_aux *info, const char *name)
> diff --git a/tools/testing/selftests/bpf/verifier/netfilter.c b/tools/testing/selftests/bpf/verifier/netfilter.c
> new file mode 100644
> index 000000000000..deeb87afdf50
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/verifier/netfilter.c
> @@ -0,0 +1,23 @@
> +{
> + "netfilter, accept all",
> + .insns = {
> + BPF_MOV64_IMM(BPF_REG_0, 1),
> + BPF_EXIT_INSN(),
> + },
> + .result = ACCEPT,
> + .prog_type = BPF_PROG_TYPE_NETFILTER,
> + .retval = 1,
> + .data = {
> + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x08, 0x00,
> + },
> +},
> +{
> + "netfilter, stolen verdict",
> + .insns = {
> + BPF_MOV64_IMM(BPF_REG_0, 2),
> + BPF_EXIT_INSN(),
> + },
> + .result = REJECT,
> + .errstr = "At program exit the register R0 has value (0x2; 0x0) should have been in (0x0; 0x1)",
> + .prog_type = BPF_PROG_TYPE_NETFILTER,
We're adding all new asm tests to test_progs now instead of test_verifier. See progs/verifier_*.c.
Other than this nit and build bot complains it looks good to me.
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