From 64e25a5d351ce3569237690054010d4aa876e18f Mon Sep 17 00:00:00 2001 From: Dmitry Yakunin Date: Mon, 3 Aug 2020 12:05:45 +0300 Subject: [PATCH] UPSTREAM: bpf: Allow to specify ifindex for skb in bpf_prog_test_run_skb Now skb->dev is unconditionally set to the loopback device in current net namespace. But if we want to test bpf program which contains code branch based on ifindex condition (eg filters out localhost packets) it is useful to allow specifying of ifindex from userspace. This patch adds such option through ctx_in (__sk_buff) parameter. Change-Id: Ia56479984ad24f3e0deb878c30dc42a6377bfb0b Signed-off-by: Dmitry Yakunin Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20200803090545.82046-3-zeil@yandex-team.ru --- net/bpf/test_run.c | 22 +++++++++++++++++-- .../selftests/bpf/prog_tests/skb_ctx.c | 5 +++++ 2 files changed, 25 insertions(+), 2 deletions(-) diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c index 0a9ff221506a..0816708a212e 100644 --- a/net/bpf/test_run.c +++ b/net/bpf/test_run.c @@ -328,6 +328,12 @@ static int convert___skb_to_skb(struct sk_buff *skb, struct __sk_buff *__skb) /* priority is allowed */ if (!range_is_zero(__skb, offsetofend(struct __sk_buff, priority), + offsetof(struct __sk_buff, ifindex))) + return -EINVAL; + + /* ifindex is allowed */ + + if (!range_is_zero(__skb, offsetofend(struct __sk_buff, ifindex), offsetof(struct __sk_buff, cb))) return -EINVAL; @@ -382,6 +388,7 @@ static void convert_skb_to___skb(struct sk_buff *skb, struct __sk_buff *__skb) __skb->mark = skb->mark; __skb->priority = skb->priority; + __skb->ifindex = skb->dev->ifindex; __skb->tstamp = skb->tstamp; memcpy(__skb->cb, &cb->data, QDISC_CB_PRIV_LEN); __skb->wire_len = cb->pkt_len; @@ -392,6 +399,8 @@ int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr, union bpf_attr __user *uattr) { bool is_l2 = false, is_direct_pkt_access = false; + struct net *net = current->nsproxy->net_ns; + struct net_device *dev = net->loopback_dev; u32 size = kattr->test.data_size_in; u32 repeat = kattr->test.repeat; struct __sk_buff *ctx = NULL; @@ -433,7 +442,7 @@ int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr, kfree(ctx); return -ENOMEM; } - sock_net_set(sk, current->nsproxy->net_ns); + sock_net_set(sk, net); sock_init_data(NULL, sk); skb = build_skb(data, 0); @@ -447,7 +456,14 @@ int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr, skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN); __skb_put(skb, size); - skb->protocol = eth_type_trans(skb, current->nsproxy->net_ns->loopback_dev); + if (ctx && ctx->ifindex > 1) { + dev = dev_get_by_index(net, ctx->ifindex); + if (!dev) { + ret = -ENODEV; + goto out; + } + } + skb->protocol = eth_type_trans(skb, dev); skb_reset_network_header(skb); switch (skb->protocol) { @@ -503,6 +519,8 @@ int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr, ret = bpf_ctx_finish(kattr, uattr, ctx, sizeof(struct __sk_buff)); out: + if (dev && dev != net->loopback_dev) + dev_put(dev); kfree_skb(skb); bpf_sk_storage_free(sk); kfree(sk); diff --git a/tools/testing/selftests/bpf/prog_tests/skb_ctx.c b/tools/testing/selftests/bpf/prog_tests/skb_ctx.c index c6d6b685a946..2d3739408b9e 100644 --- a/tools/testing/selftests/bpf/prog_tests/skb_ctx.c +++ b/tools/testing/selftests/bpf/prog_tests/skb_ctx.c @@ -10,6 +10,7 @@ void test_skb_ctx(void) .cb[3] = 4, .cb[4] = 5, .priority = 6, + .ifindex = 1, .tstamp = 7, .wire_len = 100, .gso_segs = 8, @@ -90,6 +91,10 @@ void test_skb_ctx(void) "ctx_out_priority", "skb->priority == %d, expected %d\n", skb.priority, 7); + CHECK_ATTR(skb.ifindex != 1, + "ctx_out_ifindex", + "skb->ifindex == %d, expected %d\n", + skb.ifindex, 1); CHECK_ATTR(skb.tstamp != 8, "ctx_out_tstamp", "skb->tstamp == %lld, expected %d\n",