diff options
Diffstat (limited to 'net/ipv4/ip_fragment.c')
| -rw-r--r-- | net/ipv4/ip_fragment.c | 873 |
1 files changed, 873 insertions, 0 deletions
diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c new file mode 100644 index 00000000..3727e234 --- /dev/null +++ b/net/ipv4/ip_fragment.c @@ -0,0 +1,873 @@ +/* + * INET An implementation of the TCP/IP protocol suite for the LINUX + * operating system. INET is implemented using the BSD Socket + * interface as the means of communication with the user level. + * + * The IP fragmentation functionality. + * + * Authors: Fred N. van Kempen <waltje@uWalt.NL.Mugnet.ORG> + * Alan Cox <alan@lxorguk.ukuu.org.uk> + * + * Fixes: + * Alan Cox : Split from ip.c , see ip_input.c for history. + * David S. Miller : Begin massive cleanup... + * Andi Kleen : Add sysctls. + * xxxx : Overlapfrag bug. + * Ultima : ip_expire() kernel panic. + * Bill Hawes : Frag accounting and evictor fixes. + * John McDonald : 0 length frag bug. + * Alexey Kuznetsov: SMP races, threading, cleanup. + * Patrick McHardy : LRU queue of frag heads for evictor. + */ + +#define pr_fmt(fmt) "IPv4: " fmt + +#include <linux/compiler.h> +#include <linux/module.h> +#include <linux/types.h> +#include <linux/mm.h> +#include <linux/jiffies.h> +#include <linux/skbuff.h> +#include <linux/list.h> +#include <linux/ip.h> +#include <linux/icmp.h> +#include <linux/netdevice.h> +#include <linux/jhash.h> +#include <linux/random.h> +#include <linux/slab.h> +#include <net/route.h> +#include <net/dst.h> +#include <net/sock.h> +#include <net/ip.h> +#include <net/icmp.h> +#include <net/checksum.h> +#include <net/inetpeer.h> +#include <net/inet_frag.h> +#include <linux/tcp.h> +#include <linux/udp.h> +#include <linux/inet.h> +#include <linux/netfilter_ipv4.h> +#include <net/inet_ecn.h> + +/* NOTE. Logic of IP defragmentation is parallel to corresponding IPv6 + * code now. If you change something here, _PLEASE_ update ipv6/reassembly.c + * as well. Or notify me, at least. --ANK + */ + +static int sysctl_ipfrag_max_dist __read_mostly = 64; + +struct ipfrag_skb_cb +{ + struct inet_skb_parm h; + int offset; +}; + +#define FRAG_CB(skb) ((struct ipfrag_skb_cb *)((skb)->cb)) + +/* Describe an entry in the "incomplete datagrams" queue. */ +struct ipq { + struct inet_frag_queue q; + + u32 user; + __be32 saddr; + __be32 daddr; + __be16 id; + u8 protocol; + u8 ecn; /* RFC3168 support */ + int iif; + unsigned int rid; + struct inet_peer *peer; +}; + +/* RFC 3168 support : + * We want to check ECN values of all fragments, do detect invalid combinations. + * In ipq->ecn, we store the OR value of each ip4_frag_ecn() fragment value. + */ +#define IPFRAG_ECN_NOT_ECT 0x01 /* one frag had ECN_NOT_ECT */ +#define IPFRAG_ECN_ECT_1 0x02 /* one frag had ECN_ECT_1 */ +#define IPFRAG_ECN_ECT_0 0x04 /* one frag had ECN_ECT_0 */ +#define IPFRAG_ECN_CE 0x08 /* one frag had ECN_CE */ + +static inline u8 ip4_frag_ecn(u8 tos) +{ + return 1 << (tos & INET_ECN_MASK); +} + +/* Given the OR values of all fragments, apply RFC 3168 5.3 requirements + * Value : 0xff if frame should be dropped. + * 0 or INET_ECN_CE value, to be ORed in to final iph->tos field + */ +static const u8 ip4_frag_ecn_table[16] = { + /* at least one fragment had CE, and others ECT_0 or ECT_1 */ + [IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0] = INET_ECN_CE, + [IPFRAG_ECN_CE | IPFRAG_ECN_ECT_1] = INET_ECN_CE, + [IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0 | IPFRAG_ECN_ECT_1] = INET_ECN_CE, + + /* invalid combinations : drop frame */ + [IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE] = 0xff, + [IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_ECT_0] = 0xff, + [IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_ECT_1] = 0xff, + [IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_ECT_0 | IPFRAG_ECN_ECT_1] = 0xff, + [IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0] = 0xff, + [IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE | IPFRAG_ECN_ECT_1] = 0xff, + [IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0 | IPFRAG_ECN_ECT_1] = 0xff, +}; + +static struct inet_frags ip4_frags; + +int ip_frag_nqueues(struct net *net) +{ + return net->ipv4.frags.nqueues; +} + +int ip_frag_mem(struct net *net) +{ + return atomic_read(&net->ipv4.frags.mem); +} + +static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev, + struct net_device *dev); + +struct ip4_create_arg { + struct iphdr *iph; + u32 user; +}; + +static unsigned int ipqhashfn(__be16 id, __be32 saddr, __be32 daddr, u8 prot) +{ + return jhash_3words((__force u32)id << 16 | prot, + (__force u32)saddr, (__force u32)daddr, + ip4_frags.rnd) & (INETFRAGS_HASHSZ - 1); +} + +static unsigned int ip4_hashfn(struct inet_frag_queue *q) +{ + struct ipq *ipq; + + ipq = container_of(q, struct ipq, q); + return ipqhashfn(ipq->id, ipq->saddr, ipq->daddr, ipq->protocol); +} + +static int ip4_frag_match(struct inet_frag_queue *q, void *a) +{ + struct ipq *qp; + struct ip4_create_arg *arg = a; + + qp = container_of(q, struct ipq, q); + return qp->id == arg->iph->id && + qp->saddr == arg->iph->saddr && + qp->daddr == arg->iph->daddr && + qp->protocol == arg->iph->protocol && + qp->user == arg->user; +} + +/* Memory Tracking Functions. */ +static void frag_kfree_skb(struct netns_frags *nf, struct sk_buff *skb) +{ + atomic_sub(skb->truesize, &nf->mem); + kfree_skb(skb); +} + +static void ip4_frag_init(struct inet_frag_queue *q, void *a) +{ + struct ipq *qp = container_of(q, struct ipq, q); + struct ip4_create_arg *arg = a; + + qp->protocol = arg->iph->protocol; + qp->id = arg->iph->id; + qp->ecn = ip4_frag_ecn(arg->iph->tos); + qp->saddr = arg->iph->saddr; + qp->daddr = arg->iph->daddr; + qp->user = arg->user; + qp->peer = sysctl_ipfrag_max_dist ? + inet_getpeer_v4(arg->iph->saddr, 1) : NULL; +} + +static __inline__ void ip4_frag_free(struct inet_frag_queue *q) +{ + struct ipq *qp; + + qp = container_of(q, struct ipq, q); + if (qp->peer) + inet_putpeer(qp->peer); +} + + +/* Destruction primitives. */ + +static __inline__ void ipq_put(struct ipq *ipq) +{ + inet_frag_put(&ipq->q, &ip4_frags); +} + +/* Kill ipq entry. It is not destroyed immediately, + * because caller (and someone more) holds reference count. + */ +static void ipq_kill(struct ipq *ipq) +{ + inet_frag_kill(&ipq->q, &ip4_frags); +} + +/* Memory limiting on fragments. Evictor trashes the oldest + * fragment queue until we are back under the threshold. + */ +static void ip_evictor(struct net *net) +{ + int evicted; + + evicted = inet_frag_evictor(&net->ipv4.frags, &ip4_frags); + if (evicted) + IP_ADD_STATS_BH(net, IPSTATS_MIB_REASMFAILS, evicted); +} + +/* + * Oops, a fragment queue timed out. Kill it and send an ICMP reply. + */ +static void ip_expire(unsigned long arg) +{ + struct ipq *qp; + struct net *net; + + qp = container_of((struct inet_frag_queue *) arg, struct ipq, q); + net = container_of(qp->q.net, struct net, ipv4.frags); + + spin_lock(&qp->q.lock); + + if (qp->q.last_in & INET_FRAG_COMPLETE) + goto out; + + ipq_kill(qp); + + IP_INC_STATS_BH(net, IPSTATS_MIB_REASMTIMEOUT); + IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS); + + if ((qp->q.last_in & INET_FRAG_FIRST_IN) && qp->q.fragments != NULL) { + struct sk_buff *head = qp->q.fragments; + const struct iphdr *iph; + int err; + + rcu_read_lock(); + head->dev = dev_get_by_index_rcu(net, qp->iif); + if (!head->dev) + goto out_rcu_unlock; + + /* skb dst is stale, drop it, and perform route lookup again */ + skb_dst_drop(head); + iph = ip_hdr(head); + err = ip_route_input_noref(head, iph->daddr, iph->saddr, + iph->tos, head->dev); + if (err) + goto out_rcu_unlock; + + /* + * Only an end host needs to send an ICMP + * "Fragment Reassembly Timeout" message, per RFC792. + */ + if (qp->user == IP_DEFRAG_AF_PACKET || + (qp->user == IP_DEFRAG_CONNTRACK_IN && + skb_rtable(head)->rt_type != RTN_LOCAL)) + goto out_rcu_unlock; + + + /* Send an ICMP "Fragment Reassembly Timeout" message. */ + icmp_send(head, ICMP_TIME_EXCEEDED, ICMP_EXC_FRAGTIME, 0); +out_rcu_unlock: + rcu_read_unlock(); + } +out: + spin_unlock(&qp->q.lock); + ipq_put(qp); +} + +/* Find the correct entry in the "incomplete datagrams" queue for + * this IP datagram, and create new one, if nothing is found. + */ +static inline struct ipq *ip_find(struct net *net, struct iphdr *iph, u32 user) +{ + struct inet_frag_queue *q; + struct ip4_create_arg arg; + unsigned int hash; + + arg.iph = iph; + arg.user = user; + + read_lock(&ip4_frags.lock); + hash = ipqhashfn(iph->id, iph->saddr, iph->daddr, iph->protocol); + + q = inet_frag_find(&net->ipv4.frags, &ip4_frags, &arg, hash); + if (q == NULL) + goto out_nomem; + + return container_of(q, struct ipq, q); + +out_nomem: + LIMIT_NETDEBUG(KERN_ERR pr_fmt("ip_frag_create: no memory left !\n")); + return NULL; +} + +/* Is the fragment too far ahead to be part of ipq? */ +static inline int ip_frag_too_far(struct ipq *qp) +{ + struct inet_peer *peer = qp->peer; + unsigned int max = sysctl_ipfrag_max_dist; + unsigned int start, end; + + int rc; + + if (!peer || !max) + return 0; + + start = qp->rid; + end = atomic_inc_return(&peer->rid); + qp->rid = end; + + rc = qp->q.fragments && (end - start) > max; + + if (rc) { + struct net *net; + + net = container_of(qp->q.net, struct net, ipv4.frags); + IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS); + } + + return rc; +} + +static int ip_frag_reinit(struct ipq *qp) +{ + struct sk_buff *fp; + + if (!mod_timer(&qp->q.timer, jiffies + qp->q.net->timeout)) { + atomic_inc(&qp->q.refcnt); + return -ETIMEDOUT; + } + + fp = qp->q.fragments; + do { + struct sk_buff *xp = fp->next; + frag_kfree_skb(qp->q.net, fp); + fp = xp; + } while (fp); + + qp->q.last_in = 0; + qp->q.len = 0; + qp->q.meat = 0; + qp->q.fragments = NULL; + qp->q.fragments_tail = NULL; + qp->iif = 0; + qp->ecn = 0; + + return 0; +} + +/* Add new segment to existing queue. */ +static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb) +{ + struct sk_buff *prev, *next; + struct net_device *dev; + int flags, offset; + int ihl, end; + int err = -ENOENT; + u8 ecn; + + if (qp->q.last_in & INET_FRAG_COMPLETE) + goto err; + + if (!(IPCB(skb)->flags & IPSKB_FRAG_COMPLETE) && + unlikely(ip_frag_too_far(qp)) && + unlikely(err = ip_frag_reinit(qp))) { + ipq_kill(qp); + goto err; + } + + ecn = ip4_frag_ecn(ip_hdr(skb)->tos); + offset = ntohs(ip_hdr(skb)->frag_off); + flags = offset & ~IP_OFFSET; + offset &= IP_OFFSET; + offset <<= 3; /* offset is in 8-byte chunks */ + ihl = ip_hdrlen(skb); + + /* Determine the position of this fragment. */ + end = offset + skb->len - ihl; + err = -EINVAL; + + /* Is this the final fragment? */ + if ((flags & IP_MF) == 0) { + /* If we already have some bits beyond end + * or have different end, the segment is corrupted. + */ + if (end < qp->q.len || + ((qp->q.last_in & INET_FRAG_LAST_IN) && end != qp->q.len)) + goto err; + qp->q.last_in |= INET_FRAG_LAST_IN; + qp->q.len = end; + } else { + if (end&7) { + end &= ~7; + if (skb->ip_summed != CHECKSUM_UNNECESSARY) + skb->ip_summed = CHECKSUM_NONE; + } + if (end > qp->q.len) { + /* Some bits beyond end -> corruption. */ + if (qp->q.last_in & INET_FRAG_LAST_IN) + goto err; + qp->q.len = end; + } + } + if (end == offset) + goto err; + + err = -ENOMEM; + if (pskb_pull(skb, ihl) == NULL) + goto err; + + err = pskb_trim_rcsum(skb, end - offset); + if (err) + goto err; + + /* Find out which fragments are in front and at the back of us + * in the chain of fragments so far. We must know where to put + * this fragment, right? + */ + prev = qp->q.fragments_tail; + if (!prev || FRAG_CB(prev)->offset < offset) { + next = NULL; + goto found; + } + prev = NULL; + for (next = qp->q.fragments; next != NULL; next = next->next) { + if (FRAG_CB(next)->offset >= offset) + break; /* bingo! */ + prev = next; + } + +found: + /* We found where to put this one. Check for overlap with + * preceding fragment, and, if needed, align things so that + * any overlaps are eliminated. + */ + if (prev) { + int i = (FRAG_CB(prev)->offset + prev->len) - offset; + + if (i > 0) { + offset += i; + err = -EINVAL; + if (end <= offset) + goto err; + err = -ENOMEM; + if (!pskb_pull(skb, i)) + goto err; + if (skb->ip_summed != CHECKSUM_UNNECESSARY) + skb->ip_summed = CHECKSUM_NONE; + } + } + + err = -ENOMEM; + + while (next && FRAG_CB(next)->offset < end) { + int i = end - FRAG_CB(next)->offset; /* overlap is 'i' bytes */ + + if (i < next->len) { + /* Eat head of the next overlapped fragment + * and leave the loop. The next ones cannot overlap. + */ + if (!pskb_pull(next, i)) + goto err; + FRAG_CB(next)->offset += i; + qp->q.meat -= i; + if (next->ip_summed != CHECKSUM_UNNECESSARY) + next->ip_summed = CHECKSUM_NONE; + break; + } else { + struct sk_buff *free_it = next; + + /* Old fragment is completely overridden with + * new one drop it. + */ + next = next->next; + + if (prev) + prev->next = next; + else + qp->q.fragments = next; + + qp->q.meat -= free_it->len; + frag_kfree_skb(qp->q.net, free_it); + } + } + + FRAG_CB(skb)->offset = offset; + + /* Insert this fragment in the chain of fragments. */ + skb->next = next; + if (!next) + qp->q.fragments_tail = skb; + if (prev) + prev->next = skb; + else + qp->q.fragments = skb; + + dev = skb->dev; + if (dev) { + qp->iif = dev->ifindex; + skb->dev = NULL; + } + qp->q.stamp = skb->tstamp; + qp->q.meat += skb->len; + qp->ecn |= ecn; + atomic_add(skb->truesize, &qp->q.net->mem); + if (offset == 0) + qp->q.last_in |= INET_FRAG_FIRST_IN; + + if (qp->q.last_in == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) && + qp->q.meat == qp->q.len) + return ip_frag_reasm(qp, prev, dev); + + write_lock(&ip4_frags.lock); + list_move_tail(&qp->q.lru_list, &qp->q.net->lru_list); + write_unlock(&ip4_frags.lock); + return -EINPROGRESS; + +err: + kfree_skb(skb); + return err; +} + + +/* Build a new IP datagram from all its fragments. */ + +static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev, + struct net_device *dev) +{ + struct net *net = container_of(qp->q.net, struct net, ipv4.frags); + struct iphdr *iph; + struct sk_buff *fp, *head = qp->q.fragments; + int len; + int ihlen; + int err; + u8 ecn; + + ipq_kill(qp); + + ecn = ip4_frag_ecn_table[qp->ecn]; + if (unlikely(ecn == 0xff)) { + err = -EINVAL; + goto out_fail; + } + /* Make the one we just received the head. */ + if (prev) { + head = prev->next; + fp = skb_clone(head, GFP_ATOMIC); + if (!fp) + goto out_nomem; + + fp->next = head->next; + if (!fp->next) + qp->q.fragments_tail = fp; + prev->next = fp; + + skb_morph(head, qp->q.fragments); + head->next = qp->q.fragments->next; + + kfree_skb(qp->q.fragments); + qp->q.fragments = head; + } + + WARN_ON(head == NULL); + WARN_ON(FRAG_CB(head)->offset != 0); + + /* Allocate a new buffer for the datagram. */ + ihlen = ip_hdrlen(head); + len = ihlen + qp->q.len; + + err = -E2BIG; + if (len > 65535) + goto out_oversize; + + /* Head of list must not be cloned. */ + if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC)) + goto out_nomem; + + /* If the first fragment is fragmented itself, we split + * it to two chunks: the first with data and paged part + * and the second, holding only fragments. */ + if (skb_has_frag_list(head)) { + struct sk_buff *clone; + int i, plen = 0; + + if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL) + goto out_nomem; + clone->next = head->next; + head->next = clone; + skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list; + skb_frag_list_init(head); + for (i = 0; i < skb_shinfo(head)->nr_frags; i++) + plen += skb_frag_size(&skb_shinfo(head)->frags[i]); + clone->len = clone->data_len = head->data_len - plen; + head->data_len -= clone->len; + head->len -= clone->len; + clone->csum = 0; + clone->ip_summed = head->ip_summed; + atomic_add(clone->truesize, &qp->q.net->mem); + } + + skb_shinfo(head)->frag_list = head->next; + skb_push(head, head->data - skb_network_header(head)); + + for (fp=head->next; fp; fp = fp->next) { + head->data_len += fp->len; + head->len += fp->len; + if (head->ip_summed != fp->ip_summed) + head->ip_summed = CHECKSUM_NONE; + else if (head->ip_summed == CHECKSUM_COMPLETE) + head->csum = csum_add(head->csum, fp->csum); + head->truesize += fp->truesize; + } + atomic_sub(head->truesize, &qp->q.net->mem); + + head->next = NULL; + head->dev = dev; + head->tstamp = qp->q.stamp; + + iph = ip_hdr(head); + iph->frag_off = 0; + iph->tot_len = htons(len); + iph->tos |= ecn; + IP_INC_STATS_BH(net, IPSTATS_MIB_REASMOKS); + qp->q.fragments = NULL; + qp->q.fragments_tail = NULL; + return 0; + +out_nomem: + LIMIT_NETDEBUG(KERN_ERR pr_fmt("queue_glue: no memory for gluing queue %p\n"), + qp); + err = -ENOMEM; + goto out_fail; +out_oversize: + if (net_ratelimit()) + pr_info("Oversized IP packet from %pI4\n", &qp->saddr); +out_fail: + IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS); + return err; +} + +/* Process an incoming IP datagram fragment. */ +int ip_defrag(struct sk_buff *skb, u32 user) +{ + struct ipq *qp; + struct net *net; + + net = skb->dev ? dev_net(skb->dev) : dev_net(skb_dst(skb)->dev); + IP_INC_STATS_BH(net, IPSTATS_MIB_REASMREQDS); + + /* Start by cleaning up the memory. */ + if (atomic_read(&net->ipv4.frags.mem) > net->ipv4.frags.high_thresh) + ip_evictor(net); + + /* Lookup (or create) queue header */ + if ((qp = ip_find(net, ip_hdr(skb), user)) != NULL) { + int ret; + + spin_lock(&qp->q.lock); + + ret = ip_frag_queue(qp, skb); + + spin_unlock(&qp->q.lock); + ipq_put(qp); + return ret; + } + + IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS); + kfree_skb(skb); + return -ENOMEM; +} +EXPORT_SYMBOL(ip_defrag); + +struct sk_buff *ip_check_defrag(struct sk_buff *skb, u32 user) +{ + const struct iphdr *iph; + u32 len; + + if (skb->protocol != htons(ETH_P_IP)) + return skb; + + if (!pskb_may_pull(skb, sizeof(struct iphdr))) + return skb; + + iph = ip_hdr(skb); + if (iph->ihl < 5 || iph->version != 4) + return skb; + if (!pskb_may_pull(skb, iph->ihl*4)) + return skb; + iph = ip_hdr(skb); + len = ntohs(iph->tot_len); + if (skb->len < len || len < (iph->ihl * 4)) + return skb; + + if (ip_is_fragment(ip_hdr(skb))) { + skb = skb_share_check(skb, GFP_ATOMIC); + if (skb) { + if (pskb_trim_rcsum(skb, len)) + return skb; + memset(IPCB(skb), 0, sizeof(struct inet_skb_parm)); + if (ip_defrag(skb, user)) + return NULL; + skb->rxhash = 0; + } + } + return skb; +} +EXPORT_SYMBOL(ip_check_defrag); + +#ifdef CONFIG_SYSCTL +static int zero; + +static struct ctl_table ip4_frags_ns_ctl_table[] = { + { + .procname = "ipfrag_high_thresh", + .data = &init_net.ipv4.frags.high_thresh, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec + }, + { + .procname = "ipfrag_low_thresh", + .data = &init_net.ipv4.frags.low_thresh, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec + }, + { + .procname = "ipfrag_time", + .data = &init_net.ipv4.frags.timeout, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_jiffies, + }, + { } +}; + +static struct ctl_table ip4_frags_ctl_table[] = { + { + .procname = "ipfrag_secret_interval", + .data = &ip4_frags.secret_interval, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_jiffies, + }, + { + .procname = "ipfrag_max_dist", + .data = &sysctl_ipfrag_max_dist, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = &zero + }, + { } +}; + +static int __net_init ip4_frags_ns_ctl_register(struct net *net) +{ + struct ctl_table *table; + struct ctl_table_header *hdr; + + table = ip4_frags_ns_ctl_table; + if (!net_eq(net, &init_net)) { + table = kmemdup(table, sizeof(ip4_frags_ns_ctl_table), GFP_KERNEL); + if (table == NULL) + goto err_alloc; + + table[0].data = &net->ipv4.frags.high_thresh; + table[1].data = &net->ipv4.frags.low_thresh; + table[2].data = &net->ipv4.frags.timeout; + } + + hdr = register_net_sysctl_table(net, net_ipv4_ctl_path, table); + if (hdr == NULL) + goto err_reg; + + net->ipv4.frags_hdr = hdr; + return 0; + +err_reg: + if (!net_eq(net, &init_net)) + kfree(table); +err_alloc: + return -ENOMEM; +} + +static void __net_exit ip4_frags_ns_ctl_unregister(struct net *net) +{ + struct ctl_table *table; + + table = net->ipv4.frags_hdr->ctl_table_arg; + unregister_net_sysctl_table(net->ipv4.frags_hdr); + kfree(table); +} + +static void ip4_frags_ctl_register(void) +{ + register_net_sysctl_rotable(net_ipv4_ctl_path, ip4_frags_ctl_table); +} +#else +static inline int ip4_frags_ns_ctl_register(struct net *net) +{ + return 0; +} + +static inline void ip4_frags_ns_ctl_unregister(struct net *net) +{ +} + +static inline void ip4_frags_ctl_register(void) +{ +} +#endif + +static int __net_init ipv4_frags_init_net(struct net *net) +{ + /* + * Fragment cache limits. We will commit 256K at one time. Should we + * cross that limit we will prune down to 192K. This should cope with + * even the most extreme cases without allowing an attacker to + * measurably harm machine performance. + */ + net->ipv4.frags.high_thresh = 256 * 1024; + net->ipv4.frags.low_thresh = 192 * 1024; + /* + * Important NOTE! Fragment queue must be destroyed before MSL expires. + * RFC791 is wrong proposing to prolongate timer each fragment arrival + * by TTL. + */ + net->ipv4.frags.timeout = IP_FRAG_TIME; + + inet_frags_init_net(&net->ipv4.frags); + + return ip4_frags_ns_ctl_register(net); +} + +static void __net_exit ipv4_frags_exit_net(struct net *net) +{ + ip4_frags_ns_ctl_unregister(net); + inet_frags_exit_net(&net->ipv4.frags, &ip4_frags); +} + +static struct pernet_operations ip4_frags_ops = { + .init = ipv4_frags_init_net, + .exit = ipv4_frags_exit_net, +}; + +void __init ipfrag_init(void) +{ + ip4_frags_ctl_register(); + register_pernet_subsys(&ip4_frags_ops); + ip4_frags.hashfn = ip4_hashfn; + ip4_frags.constructor = ip4_frag_init; + ip4_frags.destructor = ip4_frag_free; + ip4_frags.skb_free = NULL; + ip4_frags.qsize = sizeof(struct ipq); + ip4_frags.match = ip4_frag_match; + ip4_frags.frag_expire = ip_expire; + ip4_frags.secret_interval = 10 * 60 * HZ; + inet_frags_init(&ip4_frags); +} |