From 068d9d1eba72423e99162aad3586727180715c2a Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Tue, 11 Aug 2020 19:29:23 -0700 Subject: bpf: Fix XDP FD-based attach/detach logic around XDP_FLAGS_UPDATE_IF_NOEXIST MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Enforce XDP_FLAGS_UPDATE_IF_NOEXIST only if new BPF program to be attached is non-NULL (i.e., we are not detaching a BPF program). Fixes: d4baa9368a5e ("bpf, xdp: Extract common XDP program attachment logic") Reported-by: Stanislav Fomichev Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Tested-by: Stanislav Fomichev Acked-by: Toke Høiland-Jørgensen Link: https://lore.kernel.org/bpf/20200812022923.1217922-1-andriin@fb.com --- net/core/dev.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'net/core/dev.c') diff --git a/net/core/dev.c b/net/core/dev.c index 7df6c9617321..b5d1129d8310 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -8913,10 +8913,6 @@ static int dev_xdp_attach(struct net_device *dev, struct netlink_ext_ack *extack NL_SET_ERR_MSG(extack, "Active program does not match expected"); return -EEXIST; } - if ((flags & XDP_FLAGS_UPDATE_IF_NOEXIST) && cur_prog) { - NL_SET_ERR_MSG(extack, "XDP program already attached"); - return -EBUSY; - } /* put effective new program into new_prog */ if (link) @@ -8927,6 +8923,10 @@ static int dev_xdp_attach(struct net_device *dev, struct netlink_ext_ack *extack enum bpf_xdp_mode other_mode = mode == XDP_MODE_SKB ? XDP_MODE_DRV : XDP_MODE_SKB; + if ((flags & XDP_FLAGS_UPDATE_IF_NOEXIST) && cur_prog) { + NL_SET_ERR_MSG(extack, "XDP program already attached"); + return -EBUSY; + } if (!offload && dev_xdp_prog(dev, other_mode)) { NL_SET_ERR_MSG(extack, "Native and generic XDP can't be active at the same time"); return -EEXIST; -- cgit v1.2.3 From f8414a8d886b613b90d9fdf7cda6feea313b1069 Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Sat, 15 Aug 2020 09:29:30 +0200 Subject: net: xdp: pull ethernet header off packet after computing skb->protocol When an XDP program changes the ethernet header protocol field, eth_type_trans is used to recalculate skb->protocol. In order for eth_type_trans to work correctly, the ethernet header must actually be part of the skb data segment, so the code first pushes that onto the head of the skb. However, it subsequently forgets to pull it back off, making the behavior of the passed-on packet inconsistent between the protocol modifying case and the static protocol case. This patch fixes the issue by simply pulling the ethernet header back off of the skb head. Fixes: 297249569932 ("net: fix generic XDP to handle if eth header was mangled") Cc: Jesper Dangaard Brouer Cc: David S. Miller Signed-off-by: Jason A. Donenfeld Signed-off-by: David S. Miller --- net/core/dev.c | 1 + 1 file changed, 1 insertion(+) (limited to 'net/core/dev.c') diff --git a/net/core/dev.c b/net/core/dev.c index b5d1129d8310..7592d7dd6109 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4676,6 +4676,7 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb, (orig_bcast != is_multicast_ether_addr_64bits(eth->h_dest))) { __skb_push(skb, ETH_HLEN); skb->protocol = eth_type_trans(skb, skb->dev); + __skb_pull(skb, ETH_HLEN); } switch (act) { -- cgit v1.2.3 From 7f9bf6e82461b97ce43a912cb4a959c5a41367ac Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Mon, 17 Aug 2020 11:48:05 -0700 Subject: Revert "net: xdp: pull ethernet header off packet after computing skb->protocol" This reverts commit f8414a8d886b613b90d9fdf7cda6feea313b1069. eth_type_trans() does the necessary pull on the skb. Signed-off-by: David S. Miller --- net/core/dev.c | 1 - 1 file changed, 1 deletion(-) (limited to 'net/core/dev.c') diff --git a/net/core/dev.c b/net/core/dev.c index 7592d7dd6109..b5d1129d8310 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4676,7 +4676,6 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb, (orig_bcast != is_multicast_ether_addr_64bits(eth->h_dest))) { __skb_push(skb, ETH_HLEN); skb->protocol = eth_type_trans(skb, skb->dev); - __skb_pull(skb, ETH_HLEN); } switch (act) { -- cgit v1.2.3 From c8a36f1945b2b1b3f9823b66fc2181dc069cf803 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Wed, 19 Aug 2020 22:28:41 -0700 Subject: bpf: xdp: Fix XDP mode when no mode flags specified 7f0a838254bd ("bpf, xdp: Maintain info on attached XDP BPF programs in net_device") inadvertently changed which XDP mode is assumed when no mode flags are specified explicitly. Previously, driver mode was preferred, if driver supported it. If not, generic SKB mode was chosen. That commit changed default to SKB mode always. This patch fixes the issue and restores the original logic. Fixes: 7f0a838254bd ("bpf, xdp: Maintain info on attached XDP BPF programs in net_device") Reported-by: Lorenzo Bianconi Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Tested-by: Lorenzo Bianconi Link: https://lore.kernel.org/bpf/20200820052841.1559757-1-andriin@fb.com --- net/core/dev.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) (limited to 'net/core/dev.c') diff --git a/net/core/dev.c b/net/core/dev.c index b5d1129d8310..d42c9ea0c3c0 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -8742,13 +8742,15 @@ struct bpf_xdp_link { int flags; }; -static enum bpf_xdp_mode dev_xdp_mode(u32 flags) +static enum bpf_xdp_mode dev_xdp_mode(struct net_device *dev, u32 flags) { if (flags & XDP_FLAGS_HW_MODE) return XDP_MODE_HW; if (flags & XDP_FLAGS_DRV_MODE) return XDP_MODE_DRV; - return XDP_MODE_SKB; + if (flags & XDP_FLAGS_SKB_MODE) + return XDP_MODE_SKB; + return dev->netdev_ops->ndo_bpf ? XDP_MODE_DRV : XDP_MODE_SKB; } static bpf_op_t dev_xdp_bpf_op(struct net_device *dev, enum bpf_xdp_mode mode) @@ -8896,7 +8898,7 @@ static int dev_xdp_attach(struct net_device *dev, struct netlink_ext_ack *extack return -EINVAL; } - mode = dev_xdp_mode(flags); + mode = dev_xdp_mode(dev, flags); /* can't replace attached link */ if (dev_xdp_link(dev, mode)) { NL_SET_ERR_MSG(extack, "Can't replace active BPF XDP link"); @@ -8984,7 +8986,7 @@ static int dev_xdp_detach_link(struct net_device *dev, ASSERT_RTNL(); - mode = dev_xdp_mode(link->flags); + mode = dev_xdp_mode(dev, link->flags); if (dev_xdp_link(dev, mode) != link) return -EINVAL; @@ -9080,7 +9082,7 @@ static int bpf_xdp_link_update(struct bpf_link *link, struct bpf_prog *new_prog, goto out_unlock; } - mode = dev_xdp_mode(xdp_link->flags); + mode = dev_xdp_mode(xdp_link->dev, xdp_link->flags); bpf_op = dev_xdp_bpf_op(xdp_link->dev, mode); err = dev_xdp_install(xdp_link->dev, mode, bpf_op, NULL, xdp_link->flags, new_prog); @@ -9164,7 +9166,7 @@ out_put_dev: int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack, int fd, int expected_fd, u32 flags) { - enum bpf_xdp_mode mode = dev_xdp_mode(flags); + enum bpf_xdp_mode mode = dev_xdp_mode(dev, flags); struct bpf_prog *new_prog = NULL, *old_prog = NULL; int err; -- cgit v1.2.3 From df561f6688fef775baa341a0f5d960becd248b11 Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Sun, 23 Aug 2020 17:36:59 -0500 Subject: treewide: Use fallthrough pseudo-keyword Replace the existing /* fall through */ comments and its variants with the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary fall-through markings when it is the case. [1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through Signed-off-by: Gustavo A. R. Silva --- net/core/dev.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'net/core/dev.c') diff --git a/net/core/dev.c b/net/core/dev.c index d42c9ea0c3c0..b9c6f31ae96e 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4690,10 +4690,10 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb, break; default: bpf_warn_invalid_xdp_action(act); - /* fall through */ + fallthrough; case XDP_ABORTED: trace_xdp_exception(skb->dev, xdp_prog, act); - /* fall through */ + fallthrough; case XDP_DROP: do_drop: kfree_skb(skb); -- cgit v1.2.3