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Message-Id: <20230405161116.13565-7-fw@strlen.de>
Date: Wed, 5 Apr 2023 18:11:16 +0200
From: Florian Westphal <fw@...len.de>
To: <netdev@...r.kernel.org>
Cc: netfilter-devel@...r.kernel.org, bpf@...r.kernel.org,
dxu@...uu.xyz, qde@...cy.de, Florian Westphal <fw@...len.de>
Subject: [PATCH bpf-next 6/6] bpf: add test_run support for netfilter program type
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,
+},
--
2.39.2
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