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net: allow gro_max_size to exceed 65536

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Allow the gro_max_size to exceed a value larger than 65536.

There weren't really any external limitations that prevented this other
than the fact that IPv4 only supports a 16 bit length field. Since we have
the option of adding a hop-by-hop header for IPv6 we can allow IPv6 to
exceed this value and for IPv4 and non-TCP flows we can cap things at 65536
via a constant rather than relying on gro_max_size.

[edumazet] limit GRO_MAX_SIZE to (8 * 65535) to avoid overflows.

Signed-off-by: Alexander Duyck <alexanderduyck@fb.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexander Duyck 2022-05-13 11:34:03 -07:00 committed by David S. Miller
parent 81fbc81213
commit 0fe79f28bf
6 changed files with 16 additions and 12 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

2
drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
View file

@ -2038,7 +2038,7 @@ mlx5e_hw_gro_skb_has_enough_space(struct sk_buff *skb, u16 data_bcnt)
{
int nr_frags = skb_shinfo(skb)->nr_frags;
return PAGE_SIZE * nr_frags + data_bcnt <= GRO_MAX_SIZE;
return PAGE_SIZE * nr_frags + data_bcnt <= GRO_LEGACY_MAX_SIZE;
}
static void

6
include/linux/netdevice.h
View file

@ -2161,7 +2161,11 @@ struct net_device {
struct bpf_prog __rcu *xdp_prog;
unsigned long gro_flush_timeout;
int napi_defer_hard_irqs;
#define GRO_MAX_SIZE 65536
#define GRO_LEGACY_MAX_SIZE 65536u
/* TCP minimal MSS is 8 (TCP_MIN_GSO_SIZE),
* and shinfo->gso_segs is a 16bit field.
*/
#define GRO_MAX_SIZE (8 * 65535u)
unsigned int gro_max_size;
rx_handler_func_t __rcu *rx_handler;
void __rcu *rx_handler_data;

2
include/net/ipv6.h
View file

@ -477,7 +477,7 @@ static inline int ipv6_has_hopopt_jumbo(const struct sk_buff *skb)
const struct hop_jumbo_hdr *jhdr;
const struct ipv6hdr *nhdr;
if (likely(skb->len <= GRO_MAX_SIZE))
if (likely(skb->len <= GRO_LEGACY_MAX_SIZE))
return 0;
if (skb->protocol != htons(ETH_P_IPV6))

2
net/core/dev.c
View file

@ -10598,7 +10598,7 @@ struct net_device *alloc_netdev_mqs(int sizeof_priv, const char *name,
dev->gso_max_size = GSO_LEGACY_MAX_SIZE;
dev->gso_max_segs = GSO_MAX_SEGS;
dev->gro_max_size = GRO_MAX_SIZE;
dev->gro_max_size = GRO_LEGACY_MAX_SIZE;
dev->tso_max_size = TSO_LEGACY_MAX_SIZE;
dev->tso_max_segs = TSO_MAX_SEGS;
dev->upper_level = 1;

8
net/core/gro.c
View file

@ -167,6 +167,14 @@ int skb_gro_receive(struct sk_buff *p, struct sk_buff *skb)
if (unlikely(p->len + len >= gro_max_size || NAPI_GRO_CB(skb)->flush))
return -E2BIG;
if (unlikely(p->len + len >= GRO_LEGACY_MAX_SIZE)) {
if (p->protocol != htons(ETH_P_IPV6) ||
skb_headroom(p) < sizeof(struct hop_jumbo_hdr) ||
ipv6_hdr(p)->nexthdr != IPPROTO_TCP ||
p->encapsulation)
return -E2BIG;
}
lp = NAPI_GRO_CB(p)->last;
pinfo = skb_shinfo(lp);

8
net/core/rtnetlink.c
View file

@ -2360,14 +2360,6 @@ static int validate_linkmsg(struct net_device *dev, struct nlattr *tb[],
}
}
if (tb[IFLA_GRO_MAX_SIZE]) {
u32 gro_max_size = nla_get_u32(tb[IFLA_GRO_MAX_SIZE]);
if (gro_max_size > GRO_MAX_SIZE) {
NL_SET_ERR_MSG(extack, "too big gro_max_size");
return -EINVAL;
}
}
return 0;
}