![Robert Shearman](/assets/img/avatar_default.png)
When attempting to free lwtunnel state after the module for the encap
has been unloaded an oops occurs:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
IP: lwtstate_free+0x18/0x40
[..]
task: ffff88003e372380 task.stack: ffffc900001fc000
RIP: 0010:lwtstate_free+0x18/0x40
RSP: 0018:ffff88003fd83e88 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff88002bbb3380 RCX: ffff88000c91a300
[..]
Call Trace:
<IRQ>
free_fib_info_rcu+0x195/0x1a0
? rt_fibinfo_free+0x50/0x50
rcu_process_callbacks+0x2d3/0x850
? rcu_process_callbacks+0x296/0x850
__do_softirq+0xe4/0x4cb
irq_exit+0xb0/0xc0
smp_apic_timer_interrupt+0x3d/0x50
apic_timer_interrupt+0x93/0xa0
[..]
Code: e8 6e c6 fc ff 89 d8 5b 5d c3 bb de ff ff ff eb f4 66 90 66 66 66 66 90 55 48 89 e5 53 0f b7 07 48 89 fb 48 8b 04 c5 00 81 d5 81 <48> 8b 40 08 48 85 c0 74 13 ff d0 48 8d 7b 20 be 20 00 00 00 e8
The problem is after the module for the encap can be unloaded the
corresponding ops is removed and is thus NULL here.
Modules implementing lwtunnel ops should not be allowed to unload
while there is state alive using those ops, so grab the module
reference for the ops on creating lwtunnel state and of course release
the reference when freeing the state.
Fixes: 1104d9ba44
("lwtunnel: Add destroy state operation")
Signed-off-by: Robert Shearman <rshearma@brocade.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
393 lines
8.3 KiB
C
393 lines
8.3 KiB
C
/*
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* lwtunnel Infrastructure for light weight tunnels like mpls
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*
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* Authors: Roopa Prabhu, <roopa@cumulusnetworks.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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*/
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#include <linux/capability.h>
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/uaccess.h>
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#include <linux/skbuff.h>
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#include <linux/netdevice.h>
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#include <linux/lwtunnel.h>
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#include <linux/in.h>
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#include <linux/init.h>
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#include <linux/err.h>
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#include <net/lwtunnel.h>
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#include <net/rtnetlink.h>
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#include <net/ip6_fib.h>
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#include <net/nexthop.h>
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#ifdef CONFIG_MODULES
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static const char *lwtunnel_encap_str(enum lwtunnel_encap_types encap_type)
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{
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/* Only lwt encaps implemented without using an interface for
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* the encap need to return a string here.
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*/
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switch (encap_type) {
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case LWTUNNEL_ENCAP_MPLS:
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return "MPLS";
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case LWTUNNEL_ENCAP_ILA:
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return "ILA";
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case LWTUNNEL_ENCAP_SEG6:
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return "SEG6";
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case LWTUNNEL_ENCAP_BPF:
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return "BPF";
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case LWTUNNEL_ENCAP_IP6:
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case LWTUNNEL_ENCAP_IP:
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case LWTUNNEL_ENCAP_NONE:
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case __LWTUNNEL_ENCAP_MAX:
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/* should not have got here */
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WARN_ON(1);
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break;
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}
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return NULL;
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}
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#endif /* CONFIG_MODULES */
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struct lwtunnel_state *lwtunnel_state_alloc(int encap_len)
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{
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struct lwtunnel_state *lws;
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lws = kzalloc(sizeof(*lws) + encap_len, GFP_ATOMIC);
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return lws;
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}
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EXPORT_SYMBOL(lwtunnel_state_alloc);
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static const struct lwtunnel_encap_ops __rcu *
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lwtun_encaps[LWTUNNEL_ENCAP_MAX + 1] __read_mostly;
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int lwtunnel_encap_add_ops(const struct lwtunnel_encap_ops *ops,
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unsigned int num)
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{
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if (num > LWTUNNEL_ENCAP_MAX)
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return -ERANGE;
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return !cmpxchg((const struct lwtunnel_encap_ops **)
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&lwtun_encaps[num],
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NULL, ops) ? 0 : -1;
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}
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EXPORT_SYMBOL(lwtunnel_encap_add_ops);
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int lwtunnel_encap_del_ops(const struct lwtunnel_encap_ops *ops,
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unsigned int encap_type)
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{
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int ret;
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if (encap_type == LWTUNNEL_ENCAP_NONE ||
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encap_type > LWTUNNEL_ENCAP_MAX)
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return -ERANGE;
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ret = (cmpxchg((const struct lwtunnel_encap_ops **)
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&lwtun_encaps[encap_type],
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ops, NULL) == ops) ? 0 : -1;
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synchronize_net();
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return ret;
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}
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EXPORT_SYMBOL(lwtunnel_encap_del_ops);
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int lwtunnel_build_state(struct net_device *dev, u16 encap_type,
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struct nlattr *encap, unsigned int family,
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const void *cfg, struct lwtunnel_state **lws)
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{
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const struct lwtunnel_encap_ops *ops;
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int ret = -EINVAL;
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if (encap_type == LWTUNNEL_ENCAP_NONE ||
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encap_type > LWTUNNEL_ENCAP_MAX)
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return ret;
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ret = -EOPNOTSUPP;
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rcu_read_lock();
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ops = rcu_dereference(lwtun_encaps[encap_type]);
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if (likely(ops && ops->build_state && try_module_get(ops->owner))) {
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ret = ops->build_state(dev, encap, family, cfg, lws);
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if (ret)
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module_put(ops->owner);
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}
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rcu_read_unlock();
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return ret;
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}
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EXPORT_SYMBOL(lwtunnel_build_state);
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int lwtunnel_valid_encap_type(u16 encap_type)
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{
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const struct lwtunnel_encap_ops *ops;
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int ret = -EINVAL;
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if (encap_type == LWTUNNEL_ENCAP_NONE ||
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encap_type > LWTUNNEL_ENCAP_MAX)
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return ret;
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rcu_read_lock();
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ops = rcu_dereference(lwtun_encaps[encap_type]);
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rcu_read_unlock();
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#ifdef CONFIG_MODULES
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if (!ops) {
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const char *encap_type_str = lwtunnel_encap_str(encap_type);
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if (encap_type_str) {
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__rtnl_unlock();
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request_module("rtnl-lwt-%s", encap_type_str);
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rtnl_lock();
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rcu_read_lock();
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ops = rcu_dereference(lwtun_encaps[encap_type]);
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rcu_read_unlock();
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}
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}
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#endif
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return ops ? 0 : -EOPNOTSUPP;
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}
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EXPORT_SYMBOL(lwtunnel_valid_encap_type);
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int lwtunnel_valid_encap_type_attr(struct nlattr *attr, int remaining)
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{
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struct rtnexthop *rtnh = (struct rtnexthop *)attr;
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struct nlattr *nla_entype;
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struct nlattr *attrs;
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struct nlattr *nla;
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u16 encap_type;
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int attrlen;
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while (rtnh_ok(rtnh, remaining)) {
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attrlen = rtnh_attrlen(rtnh);
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if (attrlen > 0) {
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attrs = rtnh_attrs(rtnh);
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nla = nla_find(attrs, attrlen, RTA_ENCAP);
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nla_entype = nla_find(attrs, attrlen, RTA_ENCAP_TYPE);
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if (nla_entype) {
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encap_type = nla_get_u16(nla_entype);
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if (lwtunnel_valid_encap_type(encap_type) != 0)
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return -EOPNOTSUPP;
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}
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}
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rtnh = rtnh_next(rtnh, &remaining);
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}
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return 0;
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}
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EXPORT_SYMBOL(lwtunnel_valid_encap_type_attr);
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void lwtstate_free(struct lwtunnel_state *lws)
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{
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const struct lwtunnel_encap_ops *ops = lwtun_encaps[lws->type];
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if (ops->destroy_state) {
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ops->destroy_state(lws);
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kfree_rcu(lws, rcu);
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} else {
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kfree(lws);
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}
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module_put(ops->owner);
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}
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EXPORT_SYMBOL(lwtstate_free);
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int lwtunnel_fill_encap(struct sk_buff *skb, struct lwtunnel_state *lwtstate)
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{
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const struct lwtunnel_encap_ops *ops;
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struct nlattr *nest;
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int ret = -EINVAL;
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if (!lwtstate)
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return 0;
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if (lwtstate->type == LWTUNNEL_ENCAP_NONE ||
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lwtstate->type > LWTUNNEL_ENCAP_MAX)
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return 0;
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ret = -EOPNOTSUPP;
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nest = nla_nest_start(skb, RTA_ENCAP);
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rcu_read_lock();
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ops = rcu_dereference(lwtun_encaps[lwtstate->type]);
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if (likely(ops && ops->fill_encap))
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ret = ops->fill_encap(skb, lwtstate);
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rcu_read_unlock();
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if (ret)
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goto nla_put_failure;
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nla_nest_end(skb, nest);
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ret = nla_put_u16(skb, RTA_ENCAP_TYPE, lwtstate->type);
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if (ret)
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goto nla_put_failure;
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return 0;
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nla_put_failure:
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nla_nest_cancel(skb, nest);
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return (ret == -EOPNOTSUPP ? 0 : ret);
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}
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EXPORT_SYMBOL(lwtunnel_fill_encap);
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int lwtunnel_get_encap_size(struct lwtunnel_state *lwtstate)
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{
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const struct lwtunnel_encap_ops *ops;
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int ret = 0;
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if (!lwtstate)
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return 0;
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if (lwtstate->type == LWTUNNEL_ENCAP_NONE ||
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lwtstate->type > LWTUNNEL_ENCAP_MAX)
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return 0;
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rcu_read_lock();
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ops = rcu_dereference(lwtun_encaps[lwtstate->type]);
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if (likely(ops && ops->get_encap_size))
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ret = nla_total_size(ops->get_encap_size(lwtstate));
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rcu_read_unlock();
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return ret;
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}
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EXPORT_SYMBOL(lwtunnel_get_encap_size);
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int lwtunnel_cmp_encap(struct lwtunnel_state *a, struct lwtunnel_state *b)
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{
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const struct lwtunnel_encap_ops *ops;
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int ret = 0;
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if (!a && !b)
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return 0;
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if (!a || !b)
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return 1;
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if (a->type != b->type)
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return 1;
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if (a->type == LWTUNNEL_ENCAP_NONE ||
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a->type > LWTUNNEL_ENCAP_MAX)
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return 0;
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rcu_read_lock();
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ops = rcu_dereference(lwtun_encaps[a->type]);
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if (likely(ops && ops->cmp_encap))
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ret = ops->cmp_encap(a, b);
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rcu_read_unlock();
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return ret;
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}
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EXPORT_SYMBOL(lwtunnel_cmp_encap);
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int lwtunnel_output(struct net *net, struct sock *sk, struct sk_buff *skb)
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{
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struct dst_entry *dst = skb_dst(skb);
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const struct lwtunnel_encap_ops *ops;
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struct lwtunnel_state *lwtstate;
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int ret = -EINVAL;
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if (!dst)
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goto drop;
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lwtstate = dst->lwtstate;
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if (lwtstate->type == LWTUNNEL_ENCAP_NONE ||
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lwtstate->type > LWTUNNEL_ENCAP_MAX)
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return 0;
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ret = -EOPNOTSUPP;
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rcu_read_lock();
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ops = rcu_dereference(lwtun_encaps[lwtstate->type]);
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if (likely(ops && ops->output))
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ret = ops->output(net, sk, skb);
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rcu_read_unlock();
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if (ret == -EOPNOTSUPP)
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goto drop;
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return ret;
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drop:
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kfree_skb(skb);
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return ret;
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}
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EXPORT_SYMBOL(lwtunnel_output);
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int lwtunnel_xmit(struct sk_buff *skb)
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{
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struct dst_entry *dst = skb_dst(skb);
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const struct lwtunnel_encap_ops *ops;
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struct lwtunnel_state *lwtstate;
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int ret = -EINVAL;
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if (!dst)
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goto drop;
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lwtstate = dst->lwtstate;
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if (lwtstate->type == LWTUNNEL_ENCAP_NONE ||
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lwtstate->type > LWTUNNEL_ENCAP_MAX)
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return 0;
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ret = -EOPNOTSUPP;
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rcu_read_lock();
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ops = rcu_dereference(lwtun_encaps[lwtstate->type]);
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if (likely(ops && ops->xmit))
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ret = ops->xmit(skb);
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rcu_read_unlock();
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if (ret == -EOPNOTSUPP)
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goto drop;
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return ret;
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drop:
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kfree_skb(skb);
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return ret;
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}
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EXPORT_SYMBOL(lwtunnel_xmit);
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int lwtunnel_input(struct sk_buff *skb)
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{
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struct dst_entry *dst = skb_dst(skb);
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const struct lwtunnel_encap_ops *ops;
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struct lwtunnel_state *lwtstate;
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int ret = -EINVAL;
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if (!dst)
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goto drop;
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lwtstate = dst->lwtstate;
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if (lwtstate->type == LWTUNNEL_ENCAP_NONE ||
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lwtstate->type > LWTUNNEL_ENCAP_MAX)
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return 0;
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ret = -EOPNOTSUPP;
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rcu_read_lock();
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ops = rcu_dereference(lwtun_encaps[lwtstate->type]);
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if (likely(ops && ops->input))
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ret = ops->input(skb);
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rcu_read_unlock();
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if (ret == -EOPNOTSUPP)
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goto drop;
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return ret;
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drop:
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kfree_skb(skb);
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return ret;
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}
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EXPORT_SYMBOL(lwtunnel_input);
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