From 2b16f048729bf35e6c28a40cbfad07239f9dcd90 Mon Sep 17 00:00:00 2001 From: Daniel Axtens Date: Wed, 31 Jan 2018 14:15:33 +1100 Subject: [PATCH 1/2] net: create skb_gso_validate_mac_len() If you take a GSO skb, and split it into packets, will the MAC length (L2 + L3 + L4 headers + payload) of those packets be small enough to fit within a given length? Move skb_gso_mac_seglen() to skbuff.h with other related functions like skb_gso_network_seglen() so we can use it, and then create skb_gso_validate_mac_len to do the full calculation. Signed-off-by: Daniel Axtens Signed-off-by: David S. Miller --- include/linux/skbuff.h | 16 +++++++++ net/core/skbuff.c | 73 +++++++++++++++++++++++++++++++----------- net/sched/sch_tbf.c | 10 ------ 3 files changed, 71 insertions(+), 28 deletions(-) diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index ac89a93b7c83..5ebc0f869720 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -3287,6 +3287,7 @@ int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen); void skb_scrub_packet(struct sk_buff *skb, bool xnet); unsigned int skb_gso_transport_seglen(const struct sk_buff *skb); bool skb_gso_validate_mtu(const struct sk_buff *skb, unsigned int mtu); +bool skb_gso_validate_mac_len(const struct sk_buff *skb, unsigned int len); struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features); struct sk_buff *skb_vlan_untag(struct sk_buff *skb); int skb_ensure_writable(struct sk_buff *skb, int write_len); @@ -4120,6 +4121,21 @@ static inline unsigned int skb_gso_network_seglen(const struct sk_buff *skb) return hdr_len + skb_gso_transport_seglen(skb); } +/** + * skb_gso_mac_seglen - Return length of individual segments of a gso packet + * + * @skb: GSO skb + * + * skb_gso_mac_seglen is used to determine the real size of the + * individual segments, including MAC/L2, Layer3 (IP, IPv6) and L4 + * headers (TCP/UDP). + */ +static inline unsigned int skb_gso_mac_seglen(const struct sk_buff *skb) +{ + unsigned int hdr_len = skb_transport_header(skb) - skb_mac_header(skb); + return hdr_len + skb_gso_transport_seglen(skb); +} + /* Local Checksum Offload. * Compute outer checksum based on the assumption that the * inner checksum will be offloaded later. diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 01e8285aea73..8c61c27c1b28 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -4913,6 +4913,45 @@ unsigned int skb_gso_transport_seglen(const struct sk_buff *skb) } EXPORT_SYMBOL_GPL(skb_gso_transport_seglen); +/** + * skb_gso_size_check - check the skb size, considering GSO_BY_FRAGS + * + * There are a couple of instances where we have a GSO skb, and we + * want to determine what size it would be after it is segmented. + * + * We might want to check: + * - L3+L4+payload size (e.g. IP forwarding) + * - L2+L3+L4+payload size (e.g. sanity check before passing to driver) + * + * This is a helper to do that correctly considering GSO_BY_FRAGS. + * + * @seg_len: The segmented length (from skb_gso_*_seglen). In the + * GSO_BY_FRAGS case this will be [header sizes + GSO_BY_FRAGS]. + * + * @max_len: The maximum permissible length. + * + * Returns true if the segmented length <= max length. + */ +static inline bool skb_gso_size_check(const struct sk_buff *skb, + unsigned int seg_len, + unsigned int max_len) { + const struct skb_shared_info *shinfo = skb_shinfo(skb); + const struct sk_buff *iter; + + if (shinfo->gso_size != GSO_BY_FRAGS) + return seg_len <= max_len; + + /* Undo this so we can re-use header sizes */ + seg_len -= GSO_BY_FRAGS; + + skb_walk_frags(skb, iter) { + if (seg_len + skb_headlen(iter) > max_len) + return false; + } + + return true; +} + /** * skb_gso_validate_mtu - Return in case such skb fits a given MTU * @@ -4924,27 +4963,25 @@ EXPORT_SYMBOL_GPL(skb_gso_transport_seglen); */ bool skb_gso_validate_mtu(const struct sk_buff *skb, unsigned int mtu) { - const struct skb_shared_info *shinfo = skb_shinfo(skb); - const struct sk_buff *iter; - unsigned int hlen; - - hlen = skb_gso_network_seglen(skb); - - if (shinfo->gso_size != GSO_BY_FRAGS) - return hlen <= mtu; - - /* Undo this so we can re-use header sizes */ - hlen -= GSO_BY_FRAGS; - - skb_walk_frags(skb, iter) { - if (hlen + skb_headlen(iter) > mtu) - return false; - } - - return true; + return skb_gso_size_check(skb, skb_gso_network_seglen(skb), mtu); } EXPORT_SYMBOL_GPL(skb_gso_validate_mtu); +/** + * skb_gso_validate_mac_len - Will a split GSO skb fit in a given length? + * + * @skb: GSO skb + * @len: length to validate against + * + * skb_gso_validate_mac_len validates if a given skb will fit a wanted + * length once split, including L2, L3 and L4 headers and the payload. + */ +bool skb_gso_validate_mac_len(const struct sk_buff *skb, unsigned int len) +{ + return skb_gso_size_check(skb, skb_gso_mac_seglen(skb), len); +} +EXPORT_SYMBOL_GPL(skb_gso_validate_mac_len); + static struct sk_buff *skb_reorder_vlan_header(struct sk_buff *skb) { if (skb_cow(skb, skb_headroom(skb)) < 0) { diff --git a/net/sched/sch_tbf.c b/net/sched/sch_tbf.c index 83e76d046993..229172d509cc 100644 --- a/net/sched/sch_tbf.c +++ b/net/sched/sch_tbf.c @@ -142,16 +142,6 @@ static u64 psched_ns_t2l(const struct psched_ratecfg *r, return len; } -/* - * Return length of individual segments of a gso packet, - * including all headers (MAC, IP, TCP/UDP) - */ -static unsigned int skb_gso_mac_seglen(const struct sk_buff *skb) -{ - unsigned int hdr_len = skb_transport_header(skb) - skb_mac_header(skb); - return hdr_len + skb_gso_transport_seglen(skb); -} - /* GSO packet is too big, segment it so that tbf can transmit * each segment in time */ From 8914a595110a6eca69a5e275b323f5d09e18f4f9 Mon Sep 17 00:00:00 2001 From: Daniel Axtens Date: Wed, 31 Jan 2018 14:15:34 +1100 Subject: [PATCH 2/2] bnx2x: disable GSO where gso_size is too big for hardware If a bnx2x card is passed a GSO packet with a gso_size larger than ~9700 bytes, it will cause a firmware error that will bring the card down: bnx2x: [bnx2x_attn_int_deasserted3:4323(enP24p1s0f0)]MC assert! bnx2x: [bnx2x_mc_assert:720(enP24p1s0f0)]XSTORM_ASSERT_LIST_INDEX 0x2 bnx2x: [bnx2x_mc_assert:736(enP24p1s0f0)]XSTORM_ASSERT_INDEX 0x0 = 0x00000000 0x25e43e47 0x00463e01 0x00010052 bnx2x: [bnx2x_mc_assert:750(enP24p1s0f0)]Chip Revision: everest3, FW Version: 7_13_1 ... (dump of values continues) ... Detect when the mac length of a GSO packet is greater than the maximum packet size (9700 bytes) and disable GSO. Signed-off-by: Daniel Axtens Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller --- .../net/ethernet/broadcom/bnx2x/bnx2x_main.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c index 7b08323e3f3d..74fc9af4aadb 100644 --- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c +++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c @@ -12934,6 +12934,24 @@ static netdev_features_t bnx2x_features_check(struct sk_buff *skb, struct net_device *dev, netdev_features_t features) { + /* + * A skb with gso_size + header length > 9700 will cause a + * firmware panic. Drop GSO support. + * + * Eventually the upper layer should not pass these packets down. + * + * For speed, if the gso_size is <= 9000, assume there will + * not be 700 bytes of headers and pass it through. Only do a + * full (slow) validation if the gso_size is > 9000. + * + * (Due to the way SKB_BY_FRAGS works this will also do a full + * validation in that case.) + */ + if (unlikely(skb_is_gso(skb) && + (skb_shinfo(skb)->gso_size > 9000) && + !skb_gso_validate_mac_len(skb, 9700))) + features &= ~NETIF_F_GSO_MASK; + features = vlan_features_check(skb, features); return vxlan_features_check(skb, features); }