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xfrm: fix race between netns cleanup and state expire notification

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The xfrm_user module registers its pernet init/exit after xfrm
itself so that its net exit function xfrm_user_net_exit() is
executed before xfrm_net_exit() which calls xfrm_state_fini() to
cleanup the SA's (xfrm states). This opens a window between
zeroing net->xfrm.nlsk pointer and deleting all xfrm_state
instances which may access it (via the timer). If an xfrm state
expires in this window, xfrm_exp_state_notify() will pass null
pointer as socket to nlmsg_multicast().

As the notifications are called inside rcu_read_lock() block, it
is sufficient to retrieve the nlsk socket with rcu_dereference()
and check the it for null.

Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Michal Kubecek 2014-06-03 10:26:06 +02:00 committed by David S. Miller
parent 1299b3c49b
commit 21ee543edc
1 changed files with 25 additions and 11 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

36
net/xfrm/xfrm_user.c
View file

@ -955,6 +955,20 @@ static struct sk_buff *xfrm_state_netlink(struct sk_buff *in_skb,
return skb;
}
/* A wrapper for nlmsg_multicast() checking that nlsk is still available.
* Must be called with RCU read lock.
*/
static inline int xfrm_nlmsg_multicast(struct net *net, struct sk_buff *skb,
u32 pid, unsigned int group)
{
struct sock *nlsk = rcu_dereference(net->xfrm.nlsk);
if (nlsk)
return nlmsg_multicast(nlsk, skb, pid, group, GFP_ATOMIC);
else
return -1;
}
static inline size_t xfrm_spdinfo_msgsize(void)
{
return NLMSG_ALIGN(4)
@ -2265,7 +2279,7 @@ static int xfrm_send_migrate(const struct xfrm_selector *sel, u8 dir, u8 type,
if (build_migrate(skb, m, num_migrate, k, sel, dir, type) < 0)
BUG();
return nlmsg_multicast(net->xfrm.nlsk, skb, 0, XFRMNLGRP_MIGRATE, GFP_ATOMIC);
return xfrm_nlmsg_multicast(net, skb, 0, XFRMNLGRP_MIGRATE);
}
#else
static int xfrm_send_migrate(const struct xfrm_selector *sel, u8 dir, u8 type,
@ -2456,7 +2470,7 @@ static int xfrm_exp_state_notify(struct xfrm_state *x, const struct km_event *c)
return -EMSGSIZE;
}
return nlmsg_multicast(net->xfrm.nlsk, skb, 0, XFRMNLGRP_EXPIRE, GFP_ATOMIC);
return xfrm_nlmsg_multicast(net, skb, 0, XFRMNLGRP_EXPIRE);
}
static int xfrm_aevent_state_notify(struct xfrm_state *x, const struct km_event *c)
@ -2471,7 +2485,7 @@ static int xfrm_aevent_state_notify(struct xfrm_state *x, const struct km_event
if (build_aevent(skb, x, c) < 0)
BUG();
return nlmsg_multicast(net->xfrm.nlsk, skb, 0, XFRMNLGRP_AEVENTS, GFP_ATOMIC);
return xfrm_nlmsg_multicast(net, skb, 0, XFRMNLGRP_AEVENTS);
}
static int xfrm_notify_sa_flush(const struct km_event *c)
@ -2497,7 +2511,7 @@ static int xfrm_notify_sa_flush(const struct km_event *c)
nlmsg_end(skb, nlh);
return nlmsg_multicast(net->xfrm.nlsk, skb, 0, XFRMNLGRP_SA, GFP_ATOMIC);
return xfrm_nlmsg_multicast(net, skb, 0, XFRMNLGRP_SA);
}
static inline size_t xfrm_sa_len(struct xfrm_state *x)
@ -2584,7 +2598,7 @@ static int xfrm_notify_sa(struct xfrm_state *x, const struct km_event *c)
nlmsg_end(skb, nlh);
return nlmsg_multicast(net->xfrm.nlsk, skb, 0, XFRMNLGRP_SA, GFP_ATOMIC);
return xfrm_nlmsg_multicast(net, skb, 0, XFRMNLGRP_SA);
out_free_skb:
kfree_skb(skb);
@ -2675,7 +2689,7 @@ static int xfrm_send_acquire(struct xfrm_state *x, struct xfrm_tmpl *xt,
if (build_acquire(skb, x, xt, xp) < 0)
BUG();
return nlmsg_multicast(net->xfrm.nlsk, skb, 0, XFRMNLGRP_ACQUIRE, GFP_ATOMIC);
return xfrm_nlmsg_multicast(net, skb, 0, XFRMNLGRP_ACQUIRE);
}
/* User gives us xfrm_user_policy_info followed by an array of 0
@ -2789,7 +2803,7 @@ static int xfrm_exp_policy_notify(struct xfrm_policy *xp, int dir, const struct
if (build_polexpire(skb, xp, dir, c) < 0)
BUG();
return nlmsg_multicast(net->xfrm.nlsk, skb, 0, XFRMNLGRP_EXPIRE, GFP_ATOMIC);
return xfrm_nlmsg_multicast(net, skb, 0, XFRMNLGRP_EXPIRE);
}
static int xfrm_notify_policy(struct xfrm_policy *xp, int dir, const struct km_event *c)
@ -2851,7 +2865,7 @@ static int xfrm_notify_policy(struct xfrm_policy *xp, int dir, const struct km_e
nlmsg_end(skb, nlh);
return nlmsg_multicast(net->xfrm.nlsk, skb, 0, XFRMNLGRP_POLICY, GFP_ATOMIC);
return xfrm_nlmsg_multicast(net, skb, 0, XFRMNLGRP_POLICY);
out_free_skb:
kfree_skb(skb);
@ -2879,7 +2893,7 @@ static int xfrm_notify_policy_flush(const struct km_event *c)
nlmsg_end(skb, nlh);
return nlmsg_multicast(net->xfrm.nlsk, skb, 0, XFRMNLGRP_POLICY, GFP_ATOMIC);
return xfrm_nlmsg_multicast(net, skb, 0, XFRMNLGRP_POLICY);
out_free_skb:
kfree_skb(skb);
@ -2948,7 +2962,7 @@ static int xfrm_send_report(struct net *net, u8 proto,
if (build_report(skb, proto, sel, addr) < 0)
BUG();
return nlmsg_multicast(net->xfrm.nlsk, skb, 0, XFRMNLGRP_REPORT, GFP_ATOMIC);
return xfrm_nlmsg_multicast(net, skb, 0, XFRMNLGRP_REPORT);
}
static inline size_t xfrm_mapping_msgsize(void)
@ -3000,7 +3014,7 @@ static int xfrm_send_mapping(struct xfrm_state *x, xfrm_address_t *ipaddr,
if (build_mapping(skb, x, ipaddr, sport) < 0)
BUG();
return nlmsg_multicast(net->xfrm.nlsk, skb, 0, XFRMNLGRP_MAPPING, GFP_ATOMIC);
return xfrm_nlmsg_multicast(net, skb, 0, XFRMNLGRP_MAPPING);
}
static bool xfrm_is_alive(const struct km_event *c)