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Subject[PATCH v3 4/6] net: ipv4: allow setting address on interface outside current namespace
Date
This patch allows an interface outside of the current namespace to be
selected when setting a new IPv4 address for a device. This uses the
IFA_TARGET_NETNSID attribute to select the namespace in which to search
for the interface to act upon.

Signed-off-by: Jonas Bonn <jonas@norrbonn.se>
---
net/ipv4/devinet.c | 61 ++++++++++++++++++++++++++++++++++------------
1 file changed, 45 insertions(+), 16 deletions(-)

diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index a4b5bd4d2c89..eecd1b0bb7d2 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -813,22 +813,17 @@ static void set_ifa_lifetime(struct in_ifaddr *ifa, __u32 valid_lft,
ifa->ifa_cstamp = ifa->ifa_tstamp;
}

-static struct in_ifaddr *rtm_to_ifaddr(struct net *net, struct nlmsghdr *nlh,
+static struct in_ifaddr *rtm_to_ifaddr(struct nlattr *tb[],
+ struct net *net, struct nlmsghdr *nlh,
__u32 *pvalid_lft, __u32 *pprefered_lft,
struct netlink_ext_ack *extack)
{
- struct nlattr *tb[IFA_MAX+1];
struct in_ifaddr *ifa;
struct ifaddrmsg *ifm;
struct net_device *dev;
struct in_device *in_dev;
int err;

- err = nlmsg_parse_deprecated(nlh, sizeof(*ifm), tb, IFA_MAX,
- ifa_ipv4_policy, extack);
- if (err < 0)
- goto errout;
-
ifm = nlmsg_data(nlh);
err = -EINVAL;
if (ifm->ifa_prefixlen > 32 || !tb[IFA_LOCAL])
@@ -922,16 +917,38 @@ static int inet_rtm_newaddr(struct sk_buff *skb, struct nlmsghdr *nlh,
struct netlink_ext_ack *extack)
{
struct net *net = sock_net(skb->sk);
+ struct net *tgt_net = NULL;
struct in_ifaddr *ifa;
struct in_ifaddr *ifa_existing;
__u32 valid_lft = INFINITY_LIFE_TIME;
__u32 prefered_lft = INFINITY_LIFE_TIME;
+ struct nlattr *tb[IFA_MAX + 1];
+ int err;

ASSERT_RTNL();

- ifa = rtm_to_ifaddr(net, nlh, &valid_lft, &prefered_lft, extack);
- if (IS_ERR(ifa))
- return PTR_ERR(ifa);
+ err = nlmsg_parse_deprecated(nlh, sizeof(struct ifaddrmsg), tb, IFA_MAX,
+ ifa_ipv4_policy, extack);
+ if (err < 0)
+ return err;
+
+ if (tb[IFA_TARGET_NETNSID]) {
+ s32 netnsid = nla_get_s32(tb[IFA_TARGET_NETNSID]);
+
+ tgt_net = rtnl_get_net_ns_capable(NETLINK_CB(skb).sk, netnsid);
+ if (IS_ERR(tgt_net)) {
+ NL_SET_ERR_MSG(extack,
+ "ipv4: Invalid target network namespace id");
+ return PTR_ERR(tgt_net);
+ }
+ net = tgt_net;
+ }
+
+ ifa = rtm_to_ifaddr(tb, net, nlh, &valid_lft, &prefered_lft, extack);
+ if (IS_ERR(ifa)) {
+ err = PTR_ERR(ifa);
+ goto out;
+ }

ifa_existing = find_matching_ifa(ifa);
if (!ifa_existing) {
@@ -945,19 +962,24 @@ static int inet_rtm_newaddr(struct sk_buff *skb, struct nlmsghdr *nlh,

if (ret < 0) {
inet_free_ifa(ifa);
- return ret;
+ err = ret;
+ goto out;
}
}
- return __inet_insert_ifa(ifa, nlh, NETLINK_CB(skb).portid,
- extack);
+ err = __inet_insert_ifa(ifa, nlh, NETLINK_CB(skb).portid,
+ extack);
+ if (err < 0)
+ goto out;
} else {
u32 new_metric = ifa->ifa_rt_priority;

inet_free_ifa(ifa);

if (nlh->nlmsg_flags & NLM_F_EXCL ||
- !(nlh->nlmsg_flags & NLM_F_REPLACE))
- return -EEXIST;
+ !(nlh->nlmsg_flags & NLM_F_REPLACE)) {
+ err = -EEXIST;
+ goto out;
+ }
ifa = ifa_existing;

if (ifa->ifa_rt_priority != new_metric) {
@@ -971,7 +993,14 @@ static int inet_rtm_newaddr(struct sk_buff *skb, struct nlmsghdr *nlh,
&check_lifetime_work, 0);
rtmsg_ifa(RTM_NEWADDR, ifa, nlh, NETLINK_CB(skb).portid);
}
- return 0;
+
+ err = 0;
+
+out:
+ if (tgt_net)
+ put_net(tgt_net);
+
+ return err;
}

/*
--
2.20.1
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