From 6eca7604f13afa67087ec9996628ce4aa881154c Mon Sep 17 00:00:00 2001 From: Mark Huang Date: Mon, 14 Aug 2006 15:10:44 +0000 Subject: [PATCH] Fix kernel panic on various SMP machines. The culprit is a null ub->skb in ulog_send(). If ulog_timer() has already been scheduled on one CPU and is spinning on the lock, and ipt_ulog_packet() flushes the queue on another CPU by calling ulog_send() right before it exits, there will be no skbuff when ulog_timer() acquires the lock and calls ulog_send(). Cancelling the timer in ulog_send() doesn't help because it has already been scheduled and is running on the first CPU. Similar problem exists in ebt_ulog.c and nfnetlink_log.c. --- net/bridge/netfilter/ebt_ulog.c | 83 +++++++++++++++++++++++++++------ net/netfilter/nfnetlink_log.c | 3 ++ 2 files changed, 71 insertions(+), 15 deletions(-) diff --git a/net/bridge/netfilter/ebt_ulog.c b/net/bridge/netfilter/ebt_ulog.c index 01af4fcef..d051e2c09 100644 --- a/net/bridge/netfilter/ebt_ulog.c +++ b/net/bridge/netfilter/ebt_ulog.c @@ -3,6 +3,7 @@ * * Authors: * Bart De Schuymer + * Harald Welte * * November, 2004 * @@ -45,7 +46,7 @@ #define PRINTR(format, args...) do { if (net_ratelimit()) \ printk(format , ## args); } while (0) -static unsigned int nlbufsiz = 4096; +static unsigned int nlbufsiz = NLMSG_GOODSIZE; module_param(nlbufsiz, uint, 0600); MODULE_PARM_DESC(nlbufsiz, "netlink buffer size (number of bytes) " "(defaults to 4096)"); @@ -78,8 +79,11 @@ static void ulog_send(unsigned int nlgroup) if (ub->qlen > 1) ub->lastnlh->nlmsg_type = NLMSG_DONE; - NETLINK_CB(ub->skb).dst_groups = 1 << nlgroup; - netlink_broadcast(ebtulognl, ub->skb, 0, 1 << nlgroup, GFP_ATOMIC); + if (!ub->skb) + return; + + NETLINK_CB(ub->skb).dst_group = nlgroup + 1; + netlink_broadcast(ebtulognl, ub->skb, 0, nlgroup + 1, GFP_ATOMIC); ub->qlen = 0; ub->skb = NULL; @@ -97,12 +101,14 @@ static void ulog_timer(unsigned long data) static struct sk_buff *ulog_alloc_skb(unsigned int size) { struct sk_buff *skb; + unsigned int n; - skb = alloc_skb(nlbufsiz, GFP_ATOMIC); + n = max(size, nlbufsiz); + skb = alloc_skb(n, GFP_ATOMIC); if (!skb) { PRINTR(KERN_ERR "ebt_ulog: can't alloc whole buffer " - "of size %ub!\n", nlbufsiz); - if (size < nlbufsiz) { + "of size %ub!\n", n); + if (n > size) { /* try to allocate only as much as we need for * current packet */ skb = alloc_skb(size, GFP_ATOMIC); @@ -115,14 +121,13 @@ static struct sk_buff *ulog_alloc_skb(unsigned int size) return skb; } -static void ebt_ulog(const struct sk_buff *skb, unsigned int hooknr, +static void ebt_ulog_packet(unsigned int hooknr, const struct sk_buff *skb, const struct net_device *in, const struct net_device *out, - const void *data, unsigned int datalen) + const struct ebt_ulog_info *uloginfo, const char *prefix) { ebt_ulog_packet_msg_t *pm; size_t size, copy_len; struct nlmsghdr *nlh; - struct ebt_ulog_info *uloginfo = (struct ebt_ulog_info *)data; unsigned int group = uloginfo->nlgroup; ebt_ulog_buff_t *ub = &ulog_buffers[group]; spinlock_t *lock = &ub->lock; @@ -162,7 +167,7 @@ static void ebt_ulog(const struct sk_buff *skb, unsigned int hooknr, pm->version = EBT_ULOG_VERSION; do_gettimeofday(&pm->stamp); if (ub->qlen == 1) - ub->skb->stamp = pm->stamp; + skb_set_timestamp(ub->skb, &pm->stamp); pm->data_len = copy_len; pm->mark = skb->nfmark; pm->hook = hooknr; @@ -216,6 +221,39 @@ alloc_failure: goto unlock; } +/* this function is registered with the netfilter core */ +static void ebt_log_packet(unsigned int pf, unsigned int hooknum, + const struct sk_buff *skb, const struct net_device *in, + const struct net_device *out, const struct nf_loginfo *li, + const char *prefix) +{ + struct ebt_ulog_info loginfo; + + if (!li || li->type != NF_LOG_TYPE_ULOG) { + loginfo.nlgroup = EBT_ULOG_DEFAULT_NLGROUP; + loginfo.cprange = 0; + loginfo.qthreshold = EBT_ULOG_DEFAULT_QTHRESHOLD; + loginfo.prefix[0] = '\0'; + } else { + loginfo.nlgroup = li->u.ulog.group; + loginfo.cprange = li->u.ulog.copy_len; + loginfo.qthreshold = li->u.ulog.qthreshold; + strlcpy(loginfo.prefix, prefix, sizeof(loginfo.prefix)); + } + + ebt_ulog_packet(hooknum, skb, in, out, &loginfo, prefix); +} + +static void ebt_ulog(const struct sk_buff *skb, unsigned int hooknr, + const struct net_device *in, const struct net_device *out, + const void *data, unsigned int datalen) +{ + struct ebt_ulog_info *uloginfo = (struct ebt_ulog_info *)data; + + ebt_ulog_packet(hooknr, skb, in, out, uloginfo, NULL); +} + + static int ebt_ulog_check(const char *tablename, unsigned int hookmask, const struct ebt_entry *e, void *data, unsigned int datalen) { @@ -240,7 +278,13 @@ static struct ebt_watcher ulog = { .me = THIS_MODULE, }; -static int __init init(void) +static struct nf_logger ebt_ulog_logger = { + .name = EBT_ULOG_WATCHER, + .logfn = &ebt_log_packet, + .me = THIS_MODULE, +}; + +static int __init ebt_ulog_init(void) { int i, ret = 0; @@ -258,20 +302,29 @@ static int __init init(void) spin_lock_init(&ulog_buffers[i].lock); } - ebtulognl = netlink_kernel_create(NETLINK_NFLOG, NULL); + ebtulognl = netlink_kernel_create(NETLINK_NFLOG, EBT_ULOG_MAXNLGROUPS, + NULL, THIS_MODULE); if (!ebtulognl) ret = -ENOMEM; else if ((ret = ebt_register_watcher(&ulog))) sock_release(ebtulognl->sk_socket); + if (nf_log_register(PF_BRIDGE, &ebt_ulog_logger) < 0) { + printk(KERN_WARNING "ebt_ulog: not logging via ulog " + "since somebody else already registered for PF_BRIDGE\n"); + /* we cannot make module load fail here, since otherwise + * ebtables userspace would abort */ + } + return ret; } -static void __exit fini(void) +static void __exit ebt_ulog_fini(void) { ebt_ulog_buff_t *ub; int i; + nf_log_unregister_logger(&ebt_ulog_logger); ebt_unregister_watcher(&ulog); for (i = 0; i < EBT_ULOG_MAXNLGROUPS; i++) { ub = &ulog_buffers[i]; @@ -287,8 +340,8 @@ static void __exit fini(void) sock_release(ebtulognl->sk_socket); } -module_init(init); -module_exit(fini); +module_init(ebt_ulog_init); +module_exit(ebt_ulog_fini); MODULE_LICENSE("GPL"); MODULE_AUTHOR("Bart De Schuymer "); MODULE_DESCRIPTION("ebtables userspace logging module for bridged Ethernet" diff --git a/net/netfilter/nfnetlink_log.c b/net/netfilter/nfnetlink_log.c index 61cdda4e5..9cc07e68b 100644 --- a/net/netfilter/nfnetlink_log.c +++ b/net/netfilter/nfnetlink_log.c @@ -369,6 +369,9 @@ __nfulnl_send(struct nfulnl_instance *inst) if (inst->qlen > 1) inst->lastnlh->nlmsg_type = NLMSG_DONE; + if (!inst->skb) + return 0; + status = nfnetlink_unicast(inst->skb, inst->peer_pid, MSG_DONTWAIT); if (status < 0) { UDEBUG("netlink_unicast() failed\n"); -- 2.47.0