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net: Add device index to tcp_md5sig 

Add support for userspace to specify a device index to limit the scope
of an entry via the TCP_MD5SIG_EXT setsockopt. The existing __tcpm_pad
is renamed to tcpm_ifindex and the new field is only checked if the new
TCP_MD5SIG_FLAG_IFINDEX is set in tcpm_flags. For now, the device index
must point to an L3 master device (e.g., VRF). The API and error
handling are setup to allow the constraint to be relaxed in the future
to any device index.

Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David Ahern 2019-12-30 14:14:29 -08:00 committed by David S. Miller
parent dea53bb80e
commit 6b102db50c
3 changed files with 40 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
include/uapi/linux/tcp.h
View File

@ -317,14 +317,15 @@ enum {
#define TCP_MD5SIG_MAXKEYLEN 80
/* tcp_md5sig extension flags for TCP_MD5SIG_EXT */
#define TCP_MD5SIG_FLAG_PREFIX 1 /* address prefix length */
#define TCP_MD5SIG_FLAG_PREFIX 0x1 /* address prefix length */
#define TCP_MD5SIG_FLAG_IFINDEX 0x2 /* ifindex set */
struct tcp_md5sig {
struct __kernel_sockaddr_storage tcpm_addr; /* address associated */
__u8 tcpm_flags; /* extension flags */
__u8 tcpm_prefixlen; /* address prefix */
__u16 tcpm_keylen; /* key length */
__u32 __tcpm_pad; /* zero */
int tcpm_ifindex; /* device index for scope */
__u8 tcpm_key[TCP_MD5SIG_MAXKEYLEN]; /* key (binary) */
};

18
net/ipv4/tcp_ipv4.c
View File

@ -1196,6 +1196,24 @@ static int tcp_v4_parse_md5_keys(struct sock *sk, int optname,
return -EINVAL;
}
if (optname == TCP_MD5SIG_EXT &&
cmd.tcpm_flags & TCP_MD5SIG_FLAG_IFINDEX) {
struct net_device *dev;
rcu_read_lock();
dev = dev_get_by_index_rcu(sock_net(sk), cmd.tcpm_ifindex);
if (dev && netif_is_l3_master(dev))
l3index = dev->ifindex;
rcu_read_unlock();
/* ok to reference set/not set outside of rcu;
* right now device MUST be an L3 master
*/
if (!dev || !l3index)
return -EINVAL;
}
addr = (union tcp_md5_addr *)&sin->sin_addr.s_addr;
if (!cmd.tcpm_keylen)

20
net/ipv6/tcp_ipv6.c
View File

@ -578,10 +578,28 @@ static int tcp_v6_parse_md5_keys(struct sock *sk, int optname,
prefixlen = ipv6_addr_v4mapped(&sin6->sin6_addr) ? 32 : 128;
}
if (optname == TCP_MD5SIG_EXT &&
cmd.tcpm_flags & TCP_MD5SIG_FLAG_IFINDEX) {
struct net_device *dev;
rcu_read_lock();
dev = dev_get_by_index_rcu(sock_net(sk), cmd.tcpm_ifindex);
if (dev && netif_is_l3_master(dev))
l3index = dev->ifindex;
rcu_read_unlock();
/* ok to reference set/not set outside of rcu;
* right now device MUST be an L3 master
*/
if (!dev || !l3index)
return -EINVAL;
}
if (!cmd.tcpm_keylen) {
if (ipv6_addr_v4mapped(&sin6->sin6_addr))
return tcp_md5_do_del(sk, (union tcp_md5_addr *)&sin6->sin6_addr.s6_addr32[3],
AF_INET, prefixlen, l3index);
AF_INET, prefixlen,
l3index);
return tcp_md5_do_del(sk, (union tcp_md5_addr *)&sin6->sin6_addr,
AF_INET6, prefixlen, l3index);
}