diff options
Diffstat (limited to 'net/ipv4/netfilter/arp_tables.c')
| -rw-r--r-- | net/ipv4/netfilter/arp_tables.c | 1667 |
1 files changed, 1667 insertions, 0 deletions
diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c new file mode 100644 index 000000000..2407066b0 --- /dev/null +++ b/net/ipv4/netfilter/arp_tables.c @@ -0,0 +1,1667 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Packet matching code for ARP packets. + * + * Based heavily, if not almost entirely, upon ip_tables.c framework. + * + * Some ARP specific bits are: + * + * Copyright (C) 2002 David S. Miller (davem@redhat.com) + * Copyright (C) 2006-2009 Patrick McHardy <kaber@trash.net> + * + */ +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt +#include <linux/kernel.h> +#include <linux/skbuff.h> +#include <linux/netdevice.h> +#include <linux/capability.h> +#include <linux/if_arp.h> +#include <linux/kmod.h> +#include <linux/vmalloc.h> +#include <linux/proc_fs.h> +#include <linux/module.h> +#include <linux/init.h> +#include <linux/mutex.h> +#include <linux/err.h> +#include <net/compat.h> +#include <net/sock.h> +#include <linux/uaccess.h> + +#include <linux/netfilter/x_tables.h> +#include <linux/netfilter_arp/arp_tables.h> +#include "../../netfilter/xt_repldata.h" + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("David S. Miller <davem@redhat.com>"); +MODULE_DESCRIPTION("arptables core"); + +void *arpt_alloc_initial_table(const struct xt_table *info) +{ + return xt_alloc_initial_table(arpt, ARPT); +} +EXPORT_SYMBOL_GPL(arpt_alloc_initial_table); + +static inline int arp_devaddr_compare(const struct arpt_devaddr_info *ap, + const char *hdr_addr, int len) +{ + int i, ret; + + if (len > ARPT_DEV_ADDR_LEN_MAX) + len = ARPT_DEV_ADDR_LEN_MAX; + + ret = 0; + for (i = 0; i < len; i++) + ret |= (hdr_addr[i] ^ ap->addr[i]) & ap->mask[i]; + + return ret != 0; +} + +/* + * Unfortunately, _b and _mask are not aligned to an int (or long int) + * Some arches dont care, unrolling the loop is a win on them. + * For other arches, we only have a 16bit alignement. + */ +static unsigned long ifname_compare(const char *_a, const char *_b, const char *_mask) +{ +#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS + unsigned long ret = ifname_compare_aligned(_a, _b, _mask); +#else + unsigned long ret = 0; + const u16 *a = (const u16 *)_a; + const u16 *b = (const u16 *)_b; + const u16 *mask = (const u16 *)_mask; + int i; + + for (i = 0; i < IFNAMSIZ/sizeof(u16); i++) + ret |= (a[i] ^ b[i]) & mask[i]; +#endif + return ret; +} + +/* Returns whether packet matches rule or not. */ +static inline int arp_packet_match(const struct arphdr *arphdr, + struct net_device *dev, + const char *indev, + const char *outdev, + const struct arpt_arp *arpinfo) +{ + const char *arpptr = (char *)(arphdr + 1); + const char *src_devaddr, *tgt_devaddr; + __be32 src_ipaddr, tgt_ipaddr; + long ret; + + if (NF_INVF(arpinfo, ARPT_INV_ARPOP, + (arphdr->ar_op & arpinfo->arpop_mask) != arpinfo->arpop)) + return 0; + + if (NF_INVF(arpinfo, ARPT_INV_ARPHRD, + (arphdr->ar_hrd & arpinfo->arhrd_mask) != arpinfo->arhrd)) + return 0; + + if (NF_INVF(arpinfo, ARPT_INV_ARPPRO, + (arphdr->ar_pro & arpinfo->arpro_mask) != arpinfo->arpro)) + return 0; + + if (NF_INVF(arpinfo, ARPT_INV_ARPHLN, + (arphdr->ar_hln & arpinfo->arhln_mask) != arpinfo->arhln)) + return 0; + + src_devaddr = arpptr; + arpptr += dev->addr_len; + memcpy(&src_ipaddr, arpptr, sizeof(u32)); + arpptr += sizeof(u32); + tgt_devaddr = arpptr; + arpptr += dev->addr_len; + memcpy(&tgt_ipaddr, arpptr, sizeof(u32)); + + if (NF_INVF(arpinfo, ARPT_INV_SRCDEVADDR, + arp_devaddr_compare(&arpinfo->src_devaddr, src_devaddr, + dev->addr_len)) || + NF_INVF(arpinfo, ARPT_INV_TGTDEVADDR, + arp_devaddr_compare(&arpinfo->tgt_devaddr, tgt_devaddr, + dev->addr_len))) + return 0; + + if (NF_INVF(arpinfo, ARPT_INV_SRCIP, + (src_ipaddr & arpinfo->smsk.s_addr) != arpinfo->src.s_addr) || + NF_INVF(arpinfo, ARPT_INV_TGTIP, + (tgt_ipaddr & arpinfo->tmsk.s_addr) != arpinfo->tgt.s_addr)) + return 0; + + /* Look for ifname matches. */ + ret = ifname_compare(indev, arpinfo->iniface, arpinfo->iniface_mask); + + if (NF_INVF(arpinfo, ARPT_INV_VIA_IN, ret != 0)) + return 0; + + ret = ifname_compare(outdev, arpinfo->outiface, arpinfo->outiface_mask); + + if (NF_INVF(arpinfo, ARPT_INV_VIA_OUT, ret != 0)) + return 0; + + return 1; +} + +static inline int arp_checkentry(const struct arpt_arp *arp) +{ + if (arp->flags & ~ARPT_F_MASK) + return 0; + if (arp->invflags & ~ARPT_INV_MASK) + return 0; + + return 1; +} + +static unsigned int +arpt_error(struct sk_buff *skb, const struct xt_action_param *par) +{ + net_err_ratelimited("arp_tables: error: '%s'\n", + (const char *)par->targinfo); + + return NF_DROP; +} + +static inline const struct xt_entry_target * +arpt_get_target_c(const struct arpt_entry *e) +{ + return arpt_get_target((struct arpt_entry *)e); +} + +static inline struct arpt_entry * +get_entry(const void *base, unsigned int offset) +{ + return (struct arpt_entry *)(base + offset); +} + +static inline +struct arpt_entry *arpt_next_entry(const struct arpt_entry *entry) +{ + return (void *)entry + entry->next_offset; +} + +unsigned int arpt_do_table(void *priv, + struct sk_buff *skb, + const struct nf_hook_state *state) +{ + const struct xt_table *table = priv; + unsigned int hook = state->hook; + static const char nulldevname[IFNAMSIZ] __attribute__((aligned(sizeof(long)))); + unsigned int verdict = NF_DROP; + const struct arphdr *arp; + struct arpt_entry *e, **jumpstack; + const char *indev, *outdev; + const void *table_base; + unsigned int cpu, stackidx = 0; + const struct xt_table_info *private; + struct xt_action_param acpar; + unsigned int addend; + + if (!pskb_may_pull(skb, arp_hdr_len(skb->dev))) + return NF_DROP; + + indev = state->in ? state->in->name : nulldevname; + outdev = state->out ? state->out->name : nulldevname; + + local_bh_disable(); + addend = xt_write_recseq_begin(); + private = READ_ONCE(table->private); /* Address dependency. */ + cpu = smp_processor_id(); + table_base = private->entries; + jumpstack = (struct arpt_entry **)private->jumpstack[cpu]; + + /* No TEE support for arptables, so no need to switch to alternate + * stack. All targets that reenter must return absolute verdicts. + */ + e = get_entry(table_base, private->hook_entry[hook]); + + acpar.state = state; + acpar.hotdrop = false; + + arp = arp_hdr(skb); + do { + const struct xt_entry_target *t; + struct xt_counters *counter; + + if (!arp_packet_match(arp, skb->dev, indev, outdev, &e->arp)) { + e = arpt_next_entry(e); + continue; + } + + counter = xt_get_this_cpu_counter(&e->counters); + ADD_COUNTER(*counter, arp_hdr_len(skb->dev), 1); + + t = arpt_get_target_c(e); + + /* Standard target? */ + if (!t->u.kernel.target->target) { + int v; + + v = ((struct xt_standard_target *)t)->verdict; + if (v < 0) { + /* Pop from stack? */ + if (v != XT_RETURN) { + verdict = (unsigned int)(-v) - 1; + break; + } + if (stackidx == 0) { + e = get_entry(table_base, + private->underflow[hook]); + } else { + e = jumpstack[--stackidx]; + e = arpt_next_entry(e); + } + continue; + } + if (table_base + v + != arpt_next_entry(e)) { + if (unlikely(stackidx >= private->stacksize)) { + verdict = NF_DROP; + break; + } + jumpstack[stackidx++] = e; + } + + e = get_entry(table_base, v); + continue; + } + + acpar.target = t->u.kernel.target; + acpar.targinfo = t->data; + verdict = t->u.kernel.target->target(skb, &acpar); + + if (verdict == XT_CONTINUE) { + /* Target might have changed stuff. */ + arp = arp_hdr(skb); + e = arpt_next_entry(e); + } else { + /* Verdict */ + break; + } + } while (!acpar.hotdrop); + xt_write_recseq_end(addend); + local_bh_enable(); + + if (acpar.hotdrop) + return NF_DROP; + else + return verdict; +} + +/* All zeroes == unconditional rule. */ +static inline bool unconditional(const struct arpt_entry *e) +{ + static const struct arpt_arp uncond; + + return e->target_offset == sizeof(struct arpt_entry) && + memcmp(&e->arp, &uncond, sizeof(uncond)) == 0; +} + +/* Figures out from what hook each rule can be called: returns 0 if + * there are loops. Puts hook bitmask in comefrom. + */ +static int mark_source_chains(const struct xt_table_info *newinfo, + unsigned int valid_hooks, void *entry0, + unsigned int *offsets) +{ + unsigned int hook; + + /* No recursion; use packet counter to save back ptrs (reset + * to 0 as we leave), and comefrom to save source hook bitmask. + */ + for (hook = 0; hook < NF_ARP_NUMHOOKS; hook++) { + unsigned int pos = newinfo->hook_entry[hook]; + struct arpt_entry *e = entry0 + pos; + + if (!(valid_hooks & (1 << hook))) + continue; + + /* Set initial back pointer. */ + e->counters.pcnt = pos; + + for (;;) { + const struct xt_standard_target *t + = (void *)arpt_get_target_c(e); + int visited = e->comefrom & (1 << hook); + + if (e->comefrom & (1 << NF_ARP_NUMHOOKS)) + return 0; + + e->comefrom + |= ((1 << hook) | (1 << NF_ARP_NUMHOOKS)); + + /* Unconditional return/END. */ + if ((unconditional(e) && + (strcmp(t->target.u.user.name, + XT_STANDARD_TARGET) == 0) && + t->verdict < 0) || visited) { + unsigned int oldpos, size; + + /* Return: backtrack through the last + * big jump. + */ + do { + e->comefrom ^= (1<<NF_ARP_NUMHOOKS); + oldpos = pos; + pos = e->counters.pcnt; + e->counters.pcnt = 0; + + /* We're at the start. */ + if (pos == oldpos) + goto next; + + e = entry0 + pos; + } while (oldpos == pos + e->next_offset); + + /* Move along one */ + size = e->next_offset; + e = entry0 + pos + size; + if (pos + size >= newinfo->size) + return 0; + e->counters.pcnt = pos; + pos += size; + } else { + int newpos = t->verdict; + + if (strcmp(t->target.u.user.name, + XT_STANDARD_TARGET) == 0 && + newpos >= 0) { + /* This a jump; chase it. */ + if (!xt_find_jump_offset(offsets, newpos, + newinfo->number)) + return 0; + } else { + /* ... this is a fallthru */ + newpos = pos + e->next_offset; + if (newpos >= newinfo->size) + return 0; + } + e = entry0 + newpos; + e->counters.pcnt = pos; + pos = newpos; + } + } +next: ; + } + return 1; +} + +static int check_target(struct arpt_entry *e, struct net *net, const char *name) +{ + struct xt_entry_target *t = arpt_get_target(e); + struct xt_tgchk_param par = { + .net = net, + .table = name, + .entryinfo = e, + .target = t->u.kernel.target, + .targinfo = t->data, + .hook_mask = e->comefrom, + .family = NFPROTO_ARP, + }; + + return xt_check_target(&par, t->u.target_size - sizeof(*t), 0, false); +} + +static int +find_check_entry(struct arpt_entry *e, struct net *net, const char *name, + unsigned int size, + struct xt_percpu_counter_alloc_state *alloc_state) +{ + struct xt_entry_target *t; + struct xt_target *target; + int ret; + + if (!xt_percpu_counter_alloc(alloc_state, &e->counters)) + return -ENOMEM; + + t = arpt_get_target(e); + target = xt_request_find_target(NFPROTO_ARP, t->u.user.name, + t->u.user.revision); + if (IS_ERR(target)) { + ret = PTR_ERR(target); + goto out; + } + t->u.kernel.target = target; + + ret = check_target(e, net, name); + if (ret) + goto err; + return 0; +err: + module_put(t->u.kernel.target->me); +out: + xt_percpu_counter_free(&e->counters); + + return ret; +} + +static bool check_underflow(const struct arpt_entry *e) +{ + const struct xt_entry_target *t; + unsigned int verdict; + + if (!unconditional(e)) + return false; + t = arpt_get_target_c(e); + if (strcmp(t->u.user.name, XT_STANDARD_TARGET) != 0) + return false; + verdict = ((struct xt_standard_target *)t)->verdict; + verdict = -verdict - 1; + return verdict == NF_DROP || verdict == NF_ACCEPT; +} + +static inline int check_entry_size_and_hooks(struct arpt_entry *e, + struct xt_table_info *newinfo, + const unsigned char *base, + const unsigned char *limit, + const unsigned int *hook_entries, + const unsigned int *underflows, + unsigned int valid_hooks) +{ + unsigned int h; + int err; + + if ((unsigned long)e % __alignof__(struct arpt_entry) != 0 || + (unsigned char *)e + sizeof(struct arpt_entry) >= limit || + (unsigned char *)e + e->next_offset > limit) + return -EINVAL; + + if (e->next_offset + < sizeof(struct arpt_entry) + sizeof(struct xt_entry_target)) + return -EINVAL; + + if (!arp_checkentry(&e->arp)) + return -EINVAL; + + err = xt_check_entry_offsets(e, e->elems, e->target_offset, + e->next_offset); + if (err) + return err; + + /* Check hooks & underflows */ + for (h = 0; h < NF_ARP_NUMHOOKS; h++) { + if (!(valid_hooks & (1 << h))) + continue; + if ((unsigned char *)e - base == hook_entries[h]) + newinfo->hook_entry[h] = hook_entries[h]; + if ((unsigned char *)e - base == underflows[h]) { + if (!check_underflow(e)) + return -EINVAL; + + newinfo->underflow[h] = underflows[h]; + } + } + + /* Clear counters and comefrom */ + e->counters = ((struct xt_counters) { 0, 0 }); + e->comefrom = 0; + return 0; +} + +static void cleanup_entry(struct arpt_entry *e, struct net *net) +{ + struct xt_tgdtor_param par; + struct xt_entry_target *t; + + t = arpt_get_target(e); + par.net = net; + par.target = t->u.kernel.target; + par.targinfo = t->data; + par.family = NFPROTO_ARP; + if (par.target->destroy != NULL) + par.target->destroy(&par); + module_put(par.target->me); + xt_percpu_counter_free(&e->counters); +} + +/* Checks and translates the user-supplied table segment (held in + * newinfo). + */ +static int translate_table(struct net *net, + struct xt_table_info *newinfo, + void *entry0, + const struct arpt_replace *repl) +{ + struct xt_percpu_counter_alloc_state alloc_state = { 0 }; + struct arpt_entry *iter; + unsigned int *offsets; + unsigned int i; + int ret = 0; + + newinfo->size = repl->size; + newinfo->number = repl->num_entries; + + /* Init all hooks to impossible value. */ + for (i = 0; i < NF_ARP_NUMHOOKS; i++) { + newinfo->hook_entry[i] = 0xFFFFFFFF; + newinfo->underflow[i] = 0xFFFFFFFF; + } + + offsets = xt_alloc_entry_offsets(newinfo->number); + if (!offsets) + return -ENOMEM; + i = 0; + + /* Walk through entries, checking offsets. */ + xt_entry_foreach(iter, entry0, newinfo->size) { + ret = check_entry_size_and_hooks(iter, newinfo, entry0, + entry0 + repl->size, + repl->hook_entry, + repl->underflow, + repl->valid_hooks); + if (ret != 0) + goto out_free; + if (i < repl->num_entries) + offsets[i] = (void *)iter - entry0; + ++i; + if (strcmp(arpt_get_target(iter)->u.user.name, + XT_ERROR_TARGET) == 0) + ++newinfo->stacksize; + } + + ret = -EINVAL; + if (i != repl->num_entries) + goto out_free; + + ret = xt_check_table_hooks(newinfo, repl->valid_hooks); + if (ret) + goto out_free; + + if (!mark_source_chains(newinfo, repl->valid_hooks, entry0, offsets)) { + ret = -ELOOP; + goto out_free; + } + kvfree(offsets); + + /* Finally, each sanity check must pass */ + i = 0; + xt_entry_foreach(iter, entry0, newinfo->size) { + ret = find_check_entry(iter, net, repl->name, repl->size, + &alloc_state); + if (ret != 0) + break; + ++i; + } + + if (ret != 0) { + xt_entry_foreach(iter, entry0, newinfo->size) { + if (i-- == 0) + break; + cleanup_entry(iter, net); + } + return ret; + } + + return ret; + out_free: + kvfree(offsets); + return ret; +} + +static void get_counters(const struct xt_table_info *t, + struct xt_counters counters[]) +{ + struct arpt_entry *iter; + unsigned int cpu; + unsigned int i; + + for_each_possible_cpu(cpu) { + seqcount_t *s = &per_cpu(xt_recseq, cpu); + + i = 0; + xt_entry_foreach(iter, t->entries, t->size) { + struct xt_counters *tmp; + u64 bcnt, pcnt; + unsigned int start; + + tmp = xt_get_per_cpu_counter(&iter->counters, cpu); + do { + start = read_seqcount_begin(s); + bcnt = tmp->bcnt; + pcnt = tmp->pcnt; + } while (read_seqcount_retry(s, start)); + + ADD_COUNTER(counters[i], bcnt, pcnt); + ++i; + cond_resched(); + } + } +} + +static void get_old_counters(const struct xt_table_info *t, + struct xt_counters counters[]) +{ + struct arpt_entry *iter; + unsigned int cpu, i; + + for_each_possible_cpu(cpu) { + i = 0; + xt_entry_foreach(iter, t->entries, t->size) { + struct xt_counters *tmp; + + tmp = xt_get_per_cpu_counter(&iter->counters, cpu); + ADD_COUNTER(counters[i], tmp->bcnt, tmp->pcnt); + ++i; + } + cond_resched(); + } +} + +static struct xt_counters *alloc_counters(const struct xt_table *table) +{ + unsigned int countersize; + struct xt_counters *counters; + const struct xt_table_info *private = table->private; + + /* We need atomic snapshot of counters: rest doesn't change + * (other than comefrom, which userspace doesn't care + * about). + */ + countersize = sizeof(struct xt_counters) * private->number; + counters = vzalloc(countersize); + + if (counters == NULL) + return ERR_PTR(-ENOMEM); + + get_counters(private, counters); + + return counters; +} + +static int copy_entries_to_user(unsigned int total_size, + const struct xt_table *table, + void __user *userptr) +{ + unsigned int off, num; + const struct arpt_entry *e; + struct xt_counters *counters; + struct xt_table_info *private = table->private; + int ret = 0; + void *loc_cpu_entry; + + counters = alloc_counters(table); + if (IS_ERR(counters)) + return PTR_ERR(counters); + + loc_cpu_entry = private->entries; + + /* FIXME: use iterator macros --RR */ + /* ... then go back and fix counters and names */ + for (off = 0, num = 0; off < total_size; off += e->next_offset, num++){ + const struct xt_entry_target *t; + + e = loc_cpu_entry + off; + if (copy_to_user(userptr + off, e, sizeof(*e))) { + ret = -EFAULT; + goto free_counters; + } + if (copy_to_user(userptr + off + + offsetof(struct arpt_entry, counters), + &counters[num], + sizeof(counters[num])) != 0) { + ret = -EFAULT; + goto free_counters; + } + + t = arpt_get_target_c(e); + if (xt_target_to_user(t, userptr + off + e->target_offset)) { + ret = -EFAULT; + goto free_counters; + } + } + + free_counters: + vfree(counters); + return ret; +} + +#ifdef CONFIG_NETFILTER_XTABLES_COMPAT +static void compat_standard_from_user(void *dst, const void *src) +{ + int v = *(compat_int_t *)src; + + if (v > 0) + v += xt_compat_calc_jump(NFPROTO_ARP, v); + memcpy(dst, &v, sizeof(v)); +} + +static int compat_standard_to_user(void __user *dst, const void *src) +{ + compat_int_t cv = *(int *)src; + + if (cv > 0) + cv -= xt_compat_calc_jump(NFPROTO_ARP, cv); + return copy_to_user(dst, &cv, sizeof(cv)) ? -EFAULT : 0; +} + +static int compat_calc_entry(const struct arpt_entry *e, + const struct xt_table_info *info, + const void *base, struct xt_table_info *newinfo) +{ + const struct xt_entry_target *t; + unsigned int entry_offset; + int off, i, ret; + + off = sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry); + entry_offset = (void *)e - base; + + t = arpt_get_target_c(e); + off += xt_compat_target_offset(t->u.kernel.target); + newinfo->size -= off; + ret = xt_compat_add_offset(NFPROTO_ARP, entry_offset, off); + if (ret) + return ret; + + for (i = 0; i < NF_ARP_NUMHOOKS; i++) { + if (info->hook_entry[i] && + (e < (struct arpt_entry *)(base + info->hook_entry[i]))) + newinfo->hook_entry[i] -= off; + if (info->underflow[i] && + (e < (struct arpt_entry *)(base + info->underflow[i]))) + newinfo->underflow[i] -= off; + } + return 0; +} + +static int compat_table_info(const struct xt_table_info *info, + struct xt_table_info *newinfo) +{ + struct arpt_entry *iter; + const void *loc_cpu_entry; + int ret; + + if (!newinfo || !info) + return -EINVAL; + + /* we dont care about newinfo->entries */ + memcpy(newinfo, info, offsetof(struct xt_table_info, entries)); + newinfo->initial_entries = 0; + loc_cpu_entry = info->entries; + ret = xt_compat_init_offsets(NFPROTO_ARP, info->number); + if (ret) + return ret; + xt_entry_foreach(iter, loc_cpu_entry, info->size) { + ret = compat_calc_entry(iter, info, loc_cpu_entry, newinfo); + if (ret != 0) + return ret; + } + return 0; +} +#endif + +static int get_info(struct net *net, void __user *user, const int *len) +{ + char name[XT_TABLE_MAXNAMELEN]; + struct xt_table *t; + int ret; + + if (*len != sizeof(struct arpt_getinfo)) + return -EINVAL; + + if (copy_from_user(name, user, sizeof(name)) != 0) + return -EFAULT; + + name[XT_TABLE_MAXNAMELEN-1] = '\0'; +#ifdef CONFIG_NETFILTER_XTABLES_COMPAT + if (in_compat_syscall()) + xt_compat_lock(NFPROTO_ARP); +#endif + t = xt_request_find_table_lock(net, NFPROTO_ARP, name); + if (!IS_ERR(t)) { + struct arpt_getinfo info; + const struct xt_table_info *private = t->private; +#ifdef CONFIG_NETFILTER_XTABLES_COMPAT + struct xt_table_info tmp; + + if (in_compat_syscall()) { + ret = compat_table_info(private, &tmp); + xt_compat_flush_offsets(NFPROTO_ARP); + private = &tmp; + } +#endif + memset(&info, 0, sizeof(info)); + info.valid_hooks = t->valid_hooks; + memcpy(info.hook_entry, private->hook_entry, + sizeof(info.hook_entry)); + memcpy(info.underflow, private->underflow, + sizeof(info.underflow)); + info.num_entries = private->number; + info.size = private->size; + strcpy(info.name, name); + + if (copy_to_user(user, &info, *len) != 0) + ret = -EFAULT; + else + ret = 0; + xt_table_unlock(t); + module_put(t->me); + } else + ret = PTR_ERR(t); +#ifdef CONFIG_NETFILTER_XTABLES_COMPAT + if (in_compat_syscall()) + xt_compat_unlock(NFPROTO_ARP); +#endif + return ret; +} + +static int get_entries(struct net *net, struct arpt_get_entries __user *uptr, + const int *len) +{ + int ret; + struct arpt_get_entries get; + struct xt_table *t; + + if (*len < sizeof(get)) + return -EINVAL; + if (copy_from_user(&get, uptr, sizeof(get)) != 0) + return -EFAULT; + if (*len != sizeof(struct arpt_get_entries) + get.size) + return -EINVAL; + + get.name[sizeof(get.name) - 1] = '\0'; + + t = xt_find_table_lock(net, NFPROTO_ARP, get.name); + if (!IS_ERR(t)) { + const struct xt_table_info *private = t->private; + + if (get.size == private->size) + ret = copy_entries_to_user(private->size, + t, uptr->entrytable); + else + ret = -EAGAIN; + + module_put(t->me); + xt_table_unlock(t); + } else + ret = PTR_ERR(t); + + return ret; +} + +static int __do_replace(struct net *net, const char *name, + unsigned int valid_hooks, + struct xt_table_info *newinfo, + unsigned int num_counters, + void __user *counters_ptr) +{ + int ret; + struct xt_table *t; + struct xt_table_info *oldinfo; + struct xt_counters *counters; + void *loc_cpu_old_entry; + struct arpt_entry *iter; + + ret = 0; + counters = xt_counters_alloc(num_counters); + if (!counters) { + ret = -ENOMEM; + goto out; + } + + t = xt_request_find_table_lock(net, NFPROTO_ARP, name); + if (IS_ERR(t)) { + ret = PTR_ERR(t); + goto free_newinfo_counters_untrans; + } + + /* You lied! */ + if (valid_hooks != t->valid_hooks) { + ret = -EINVAL; + goto put_module; + } + + oldinfo = xt_replace_table(t, num_counters, newinfo, &ret); + if (!oldinfo) + goto put_module; + + /* Update module usage count based on number of rules */ + if ((oldinfo->number > oldinfo->initial_entries) || + (newinfo->number <= oldinfo->initial_entries)) + module_put(t->me); + if ((oldinfo->number > oldinfo->initial_entries) && + (newinfo->number <= oldinfo->initial_entries)) + module_put(t->me); + + xt_table_unlock(t); + + get_old_counters(oldinfo, counters); + + /* Decrease module usage counts and free resource */ + loc_cpu_old_entry = oldinfo->entries; + xt_entry_foreach(iter, loc_cpu_old_entry, oldinfo->size) + cleanup_entry(iter, net); + + xt_free_table_info(oldinfo); + if (copy_to_user(counters_ptr, counters, + sizeof(struct xt_counters) * num_counters) != 0) { + /* Silent error, can't fail, new table is already in place */ + net_warn_ratelimited("arptables: counters copy to user failed while replacing table\n"); + } + vfree(counters); + return ret; + + put_module: + module_put(t->me); + xt_table_unlock(t); + free_newinfo_counters_untrans: + vfree(counters); + out: + return ret; +} + +static int do_replace(struct net *net, sockptr_t arg, unsigned int len) +{ + int ret; + struct arpt_replace tmp; + struct xt_table_info *newinfo; + void *loc_cpu_entry; + struct arpt_entry *iter; + + if (copy_from_sockptr(&tmp, arg, sizeof(tmp)) != 0) + return -EFAULT; + + /* overflow check */ + if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters)) + return -ENOMEM; + if (tmp.num_counters == 0) + return -EINVAL; + + tmp.name[sizeof(tmp.name)-1] = 0; + + newinfo = xt_alloc_table_info(tmp.size); + if (!newinfo) + return -ENOMEM; + + loc_cpu_entry = newinfo->entries; + if (copy_from_sockptr_offset(loc_cpu_entry, arg, sizeof(tmp), + tmp.size) != 0) { + ret = -EFAULT; + goto free_newinfo; + } + + ret = translate_table(net, newinfo, loc_cpu_entry, &tmp); + if (ret != 0) + goto free_newinfo; + + ret = __do_replace(net, tmp.name, tmp.valid_hooks, newinfo, + tmp.num_counters, tmp.counters); + if (ret) + goto free_newinfo_untrans; + return 0; + + free_newinfo_untrans: + xt_entry_foreach(iter, loc_cpu_entry, newinfo->size) + cleanup_entry(iter, net); + free_newinfo: + xt_free_table_info(newinfo); + return ret; +} + +static int do_add_counters(struct net *net, sockptr_t arg, unsigned int len) +{ + unsigned int i; + struct xt_counters_info tmp; + struct xt_counters *paddc; + struct xt_table *t; + const struct xt_table_info *private; + int ret = 0; + struct arpt_entry *iter; + unsigned int addend; + + paddc = xt_copy_counters(arg, len, &tmp); + if (IS_ERR(paddc)) + return PTR_ERR(paddc); + + t = xt_find_table_lock(net, NFPROTO_ARP, tmp.name); + if (IS_ERR(t)) { + ret = PTR_ERR(t); + goto free; + } + + local_bh_disable(); + private = t->private; + if (private->number != tmp.num_counters) { + ret = -EINVAL; + goto unlock_up_free; + } + + i = 0; + + addend = xt_write_recseq_begin(); + xt_entry_foreach(iter, private->entries, private->size) { + struct xt_counters *tmp; + + tmp = xt_get_this_cpu_counter(&iter->counters); + ADD_COUNTER(*tmp, paddc[i].bcnt, paddc[i].pcnt); + ++i; + } + xt_write_recseq_end(addend); + unlock_up_free: + local_bh_enable(); + xt_table_unlock(t); + module_put(t->me); + free: + vfree(paddc); + + return ret; +} + +#ifdef CONFIG_NETFILTER_XTABLES_COMPAT +struct compat_arpt_replace { + char name[XT_TABLE_MAXNAMELEN]; + u32 valid_hooks; + u32 num_entries; + u32 size; + u32 hook_entry[NF_ARP_NUMHOOKS]; + u32 underflow[NF_ARP_NUMHOOKS]; + u32 num_counters; + compat_uptr_t counters; + struct compat_arpt_entry entries[]; +}; + +static inline void compat_release_entry(struct compat_arpt_entry *e) +{ + struct xt_entry_target *t; + + t = compat_arpt_get_target(e); + module_put(t->u.kernel.target->me); +} + +static int +check_compat_entry_size_and_hooks(struct compat_arpt_entry *e, + struct xt_table_info *newinfo, + unsigned int *size, + const unsigned char *base, + const unsigned char *limit) +{ + struct xt_entry_target *t; + struct xt_target *target; + unsigned int entry_offset; + int ret, off; + + if ((unsigned long)e % __alignof__(struct compat_arpt_entry) != 0 || + (unsigned char *)e + sizeof(struct compat_arpt_entry) >= limit || + (unsigned char *)e + e->next_offset > limit) + return -EINVAL; + + if (e->next_offset < sizeof(struct compat_arpt_entry) + + sizeof(struct compat_xt_entry_target)) + return -EINVAL; + + if (!arp_checkentry(&e->arp)) + return -EINVAL; + + ret = xt_compat_check_entry_offsets(e, e->elems, e->target_offset, + e->next_offset); + if (ret) + return ret; + + off = sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry); + entry_offset = (void *)e - (void *)base; + + t = compat_arpt_get_target(e); + target = xt_request_find_target(NFPROTO_ARP, t->u.user.name, + t->u.user.revision); + if (IS_ERR(target)) { + ret = PTR_ERR(target); + goto out; + } + t->u.kernel.target = target; + + off += xt_compat_target_offset(target); + *size += off; + ret = xt_compat_add_offset(NFPROTO_ARP, entry_offset, off); + if (ret) + goto release_target; + + return 0; + +release_target: + module_put(t->u.kernel.target->me); +out: + return ret; +} + +static void +compat_copy_entry_from_user(struct compat_arpt_entry *e, void **dstptr, + unsigned int *size, + struct xt_table_info *newinfo, unsigned char *base) +{ + struct xt_entry_target *t; + struct arpt_entry *de; + unsigned int origsize; + int h; + + origsize = *size; + de = *dstptr; + memcpy(de, e, sizeof(struct arpt_entry)); + memcpy(&de->counters, &e->counters, sizeof(e->counters)); + + *dstptr += sizeof(struct arpt_entry); + *size += sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry); + + de->target_offset = e->target_offset - (origsize - *size); + t = compat_arpt_get_target(e); + xt_compat_target_from_user(t, dstptr, size); + + de->next_offset = e->next_offset - (origsize - *size); + for (h = 0; h < NF_ARP_NUMHOOKS; h++) { + if ((unsigned char *)de - base < newinfo->hook_entry[h]) + newinfo->hook_entry[h] -= origsize - *size; + if ((unsigned char *)de - base < newinfo->underflow[h]) + newinfo->underflow[h] -= origsize - *size; + } +} + +static int translate_compat_table(struct net *net, + struct xt_table_info **pinfo, + void **pentry0, + const struct compat_arpt_replace *compatr) +{ + unsigned int i, j; + struct xt_table_info *newinfo, *info; + void *pos, *entry0, *entry1; + struct compat_arpt_entry *iter0; + struct arpt_replace repl; + unsigned int size; + int ret; + + info = *pinfo; + entry0 = *pentry0; + size = compatr->size; + info->number = compatr->num_entries; + + j = 0; + xt_compat_lock(NFPROTO_ARP); + ret = xt_compat_init_offsets(NFPROTO_ARP, compatr->num_entries); + if (ret) + goto out_unlock; + /* Walk through entries, checking offsets. */ + xt_entry_foreach(iter0, entry0, compatr->size) { + ret = check_compat_entry_size_and_hooks(iter0, info, &size, + entry0, + entry0 + compatr->size); + if (ret != 0) + goto out_unlock; + ++j; + } + + ret = -EINVAL; + if (j != compatr->num_entries) + goto out_unlock; + + ret = -ENOMEM; + newinfo = xt_alloc_table_info(size); + if (!newinfo) + goto out_unlock; + + memset(newinfo->entries, 0, size); + + newinfo->number = compatr->num_entries; + for (i = 0; i < NF_ARP_NUMHOOKS; i++) { + newinfo->hook_entry[i] = compatr->hook_entry[i]; + newinfo->underflow[i] = compatr->underflow[i]; + } + entry1 = newinfo->entries; + pos = entry1; + size = compatr->size; + xt_entry_foreach(iter0, entry0, compatr->size) + compat_copy_entry_from_user(iter0, &pos, &size, + newinfo, entry1); + + /* all module references in entry0 are now gone */ + + xt_compat_flush_offsets(NFPROTO_ARP); + xt_compat_unlock(NFPROTO_ARP); + + memcpy(&repl, compatr, sizeof(*compatr)); + + for (i = 0; i < NF_ARP_NUMHOOKS; i++) { + repl.hook_entry[i] = newinfo->hook_entry[i]; + repl.underflow[i] = newinfo->underflow[i]; + } + + repl.num_counters = 0; + repl.counters = NULL; + repl.size = newinfo->size; + ret = translate_table(net, newinfo, entry1, &repl); + if (ret) + goto free_newinfo; + + *pinfo = newinfo; + *pentry0 = entry1; + xt_free_table_info(info); + return 0; + +free_newinfo: + xt_free_table_info(newinfo); + return ret; +out_unlock: + xt_compat_flush_offsets(NFPROTO_ARP); + xt_compat_unlock(NFPROTO_ARP); + xt_entry_foreach(iter0, entry0, compatr->size) { + if (j-- == 0) + break; + compat_release_entry(iter0); + } + return ret; +} + +static int compat_do_replace(struct net *net, sockptr_t arg, unsigned int len) +{ + int ret; + struct compat_arpt_replace tmp; + struct xt_table_info *newinfo; + void *loc_cpu_entry; + struct arpt_entry *iter; + + if (copy_from_sockptr(&tmp, arg, sizeof(tmp)) != 0) + return -EFAULT; + + /* overflow check */ + if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters)) + return -ENOMEM; + if (tmp.num_counters == 0) + return -EINVAL; + + tmp.name[sizeof(tmp.name)-1] = 0; + + newinfo = xt_alloc_table_info(tmp.size); + if (!newinfo) + return -ENOMEM; + + loc_cpu_entry = newinfo->entries; + if (copy_from_sockptr_offset(loc_cpu_entry, arg, sizeof(tmp), + tmp.size) != 0) { + ret = -EFAULT; + goto free_newinfo; + } + + ret = translate_compat_table(net, &newinfo, &loc_cpu_entry, &tmp); + if (ret != 0) + goto free_newinfo; + + ret = __do_replace(net, tmp.name, tmp.valid_hooks, newinfo, + tmp.num_counters, compat_ptr(tmp.counters)); + if (ret) + goto free_newinfo_untrans; + return 0; + + free_newinfo_untrans: + xt_entry_foreach(iter, loc_cpu_entry, newinfo->size) + cleanup_entry(iter, net); + free_newinfo: + xt_free_table_info(newinfo); + return ret; +} + +static int compat_copy_entry_to_user(struct arpt_entry *e, void __user **dstptr, + compat_uint_t *size, + struct xt_counters *counters, + unsigned int i) +{ + struct xt_entry_target *t; + struct compat_arpt_entry __user *ce; + u_int16_t target_offset, next_offset; + compat_uint_t origsize; + int ret; + + origsize = *size; + ce = *dstptr; + if (copy_to_user(ce, e, sizeof(struct arpt_entry)) != 0 || + copy_to_user(&ce->counters, &counters[i], + sizeof(counters[i])) != 0) + return -EFAULT; + + *dstptr += sizeof(struct compat_arpt_entry); + *size -= sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry); + + target_offset = e->target_offset - (origsize - *size); + + t = arpt_get_target(e); + ret = xt_compat_target_to_user(t, dstptr, size); + if (ret) + return ret; + next_offset = e->next_offset - (origsize - *size); + if (put_user(target_offset, &ce->target_offset) != 0 || + put_user(next_offset, &ce->next_offset) != 0) + return -EFAULT; + return 0; +} + +static int compat_copy_entries_to_user(unsigned int total_size, + struct xt_table *table, + void __user *userptr) +{ + struct xt_counters *counters; + const struct xt_table_info *private = table->private; + void __user *pos; + unsigned int size; + int ret = 0; + unsigned int i = 0; + struct arpt_entry *iter; + + counters = alloc_counters(table); + if (IS_ERR(counters)) + return PTR_ERR(counters); + + pos = userptr; + size = total_size; + xt_entry_foreach(iter, private->entries, total_size) { + ret = compat_copy_entry_to_user(iter, &pos, + &size, counters, i++); + if (ret != 0) + break; + } + vfree(counters); + return ret; +} + +struct compat_arpt_get_entries { + char name[XT_TABLE_MAXNAMELEN]; + compat_uint_t size; + struct compat_arpt_entry entrytable[]; +}; + +static int compat_get_entries(struct net *net, + struct compat_arpt_get_entries __user *uptr, + int *len) +{ + int ret; + struct compat_arpt_get_entries get; + struct xt_table *t; + + if (*len < sizeof(get)) + return -EINVAL; + if (copy_from_user(&get, uptr, sizeof(get)) != 0) + return -EFAULT; + if (*len != sizeof(struct compat_arpt_get_entries) + get.size) + return -EINVAL; + + get.name[sizeof(get.name) - 1] = '\0'; + + xt_compat_lock(NFPROTO_ARP); + t = xt_find_table_lock(net, NFPROTO_ARP, get.name); + if (!IS_ERR(t)) { + const struct xt_table_info *private = t->private; + struct xt_table_info info; + + ret = compat_table_info(private, &info); + if (!ret && get.size == info.size) { + ret = compat_copy_entries_to_user(private->size, + t, uptr->entrytable); + } else if (!ret) + ret = -EAGAIN; + + xt_compat_flush_offsets(NFPROTO_ARP); + module_put(t->me); + xt_table_unlock(t); + } else + ret = PTR_ERR(t); + + xt_compat_unlock(NFPROTO_ARP); + return ret; +} +#endif + +static int do_arpt_set_ctl(struct sock *sk, int cmd, sockptr_t arg, + unsigned int len) +{ + int ret; + + if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN)) + return -EPERM; + + switch (cmd) { + case ARPT_SO_SET_REPLACE: +#ifdef CONFIG_NETFILTER_XTABLES_COMPAT + if (in_compat_syscall()) + ret = compat_do_replace(sock_net(sk), arg, len); + else +#endif + ret = do_replace(sock_net(sk), arg, len); + break; + + case ARPT_SO_SET_ADD_COUNTERS: + ret = do_add_counters(sock_net(sk), arg, len); + break; + + default: + ret = -EINVAL; + } + + return ret; +} + +static int do_arpt_get_ctl(struct sock *sk, int cmd, void __user *user, int *len) +{ + int ret; + + if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN)) + return -EPERM; + + switch (cmd) { + case ARPT_SO_GET_INFO: + ret = get_info(sock_net(sk), user, len); + break; + + case ARPT_SO_GET_ENTRIES: +#ifdef CONFIG_NETFILTER_XTABLES_COMPAT + if (in_compat_syscall()) + ret = compat_get_entries(sock_net(sk), user, len); + else +#endif + ret = get_entries(sock_net(sk), user, len); + break; + + case ARPT_SO_GET_REVISION_TARGET: { + struct xt_get_revision rev; + + if (*len != sizeof(rev)) { + ret = -EINVAL; + break; + } + if (copy_from_user(&rev, user, sizeof(rev)) != 0) { + ret = -EFAULT; + break; + } + rev.name[sizeof(rev.name)-1] = 0; + + try_then_request_module(xt_find_revision(NFPROTO_ARP, rev.name, + rev.revision, 1, &ret), + "arpt_%s", rev.name); + break; + } + + default: + ret = -EINVAL; + } + + return ret; +} + +static void __arpt_unregister_table(struct net *net, struct xt_table *table) +{ + struct xt_table_info *private; + void *loc_cpu_entry; + struct module *table_owner = table->me; + struct arpt_entry *iter; + + private = xt_unregister_table(table); + + /* Decrease module usage counts and free resources */ + loc_cpu_entry = private->entries; + xt_entry_foreach(iter, loc_cpu_entry, private->size) + cleanup_entry(iter, net); + if (private->number > private->initial_entries) + module_put(table_owner); + xt_free_table_info(private); +} + +int arpt_register_table(struct net *net, + const struct xt_table *table, + const struct arpt_replace *repl, + const struct nf_hook_ops *template_ops) +{ + struct nf_hook_ops *ops; + unsigned int num_ops; + int ret, i; + struct xt_table_info *newinfo; + struct xt_table_info bootstrap = {0}; + void *loc_cpu_entry; + struct xt_table *new_table; + + newinfo = xt_alloc_table_info(repl->size); + if (!newinfo) + return -ENOMEM; + + loc_cpu_entry = newinfo->entries; + memcpy(loc_cpu_entry, repl->entries, repl->size); + + ret = translate_table(net, newinfo, loc_cpu_entry, repl); + if (ret != 0) { + xt_free_table_info(newinfo); + return ret; + } + + new_table = xt_register_table(net, table, &bootstrap, newinfo); + if (IS_ERR(new_table)) { + struct arpt_entry *iter; + + xt_entry_foreach(iter, loc_cpu_entry, newinfo->size) + cleanup_entry(iter, net); + xt_free_table_info(newinfo); + return PTR_ERR(new_table); + } + + num_ops = hweight32(table->valid_hooks); + if (num_ops == 0) { + ret = -EINVAL; + goto out_free; + } + + ops = kmemdup(template_ops, sizeof(*ops) * num_ops, GFP_KERNEL); + if (!ops) { + ret = -ENOMEM; + goto out_free; + } + + for (i = 0; i < num_ops; i++) + ops[i].priv = new_table; + + new_table->ops = ops; + + ret = nf_register_net_hooks(net, ops, num_ops); + if (ret != 0) + goto out_free; + + return ret; + +out_free: + __arpt_unregister_table(net, new_table); + return ret; +} + +void arpt_unregister_table_pre_exit(struct net *net, const char *name) +{ + struct xt_table *table = xt_find_table(net, NFPROTO_ARP, name); + + if (table) + nf_unregister_net_hooks(net, table->ops, hweight32(table->valid_hooks)); +} +EXPORT_SYMBOL(arpt_unregister_table_pre_exit); + +void arpt_unregister_table(struct net *net, const char *name) +{ + struct xt_table *table = xt_find_table(net, NFPROTO_ARP, name); + + if (table) + __arpt_unregister_table(net, table); +} + +/* The built-in targets: standard (NULL) and error. */ +static struct xt_target arpt_builtin_tg[] __read_mostly = { + { + .name = XT_STANDARD_TARGET, + .targetsize = sizeof(int), + .family = NFPROTO_ARP, +#ifdef CONFIG_NETFILTER_XTABLES_COMPAT + .compatsize = sizeof(compat_int_t), + .compat_from_user = compat_standard_from_user, + .compat_to_user = compat_standard_to_user, +#endif + }, + { + .name = XT_ERROR_TARGET, + .target = arpt_error, + .targetsize = XT_FUNCTION_MAXNAMELEN, + .family = NFPROTO_ARP, + }, +}; + +static struct nf_sockopt_ops arpt_sockopts = { + .pf = PF_INET, + .set_optmin = ARPT_BASE_CTL, + .set_optmax = ARPT_SO_SET_MAX+1, + .set = do_arpt_set_ctl, + .get_optmin = ARPT_BASE_CTL, + .get_optmax = ARPT_SO_GET_MAX+1, + .get = do_arpt_get_ctl, + .owner = THIS_MODULE, +}; + +static int __net_init arp_tables_net_init(struct net *net) +{ + return xt_proto_init(net, NFPROTO_ARP); +} + +static void __net_exit arp_tables_net_exit(struct net *net) +{ + xt_proto_fini(net, NFPROTO_ARP); +} + +static struct pernet_operations arp_tables_net_ops = { + .init = arp_tables_net_init, + .exit = arp_tables_net_exit, +}; + +static int __init arp_tables_init(void) +{ + int ret; + + ret = register_pernet_subsys(&arp_tables_net_ops); + if (ret < 0) + goto err1; + + /* No one else will be downing sem now, so we won't sleep */ + ret = xt_register_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg)); + if (ret < 0) + goto err2; + + /* Register setsockopt */ + ret = nf_register_sockopt(&arpt_sockopts); + if (ret < 0) + goto err4; + + return 0; + +err4: + xt_unregister_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg)); +err2: + unregister_pernet_subsys(&arp_tables_net_ops); +err1: + return ret; +} + +static void __exit arp_tables_fini(void) +{ + nf_unregister_sockopt(&arpt_sockopts); + xt_unregister_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg)); + unregister_pernet_subsys(&arp_tables_net_ops); +} + +EXPORT_SYMBOL(arpt_register_table); +EXPORT_SYMBOL(arpt_unregister_table); +EXPORT_SYMBOL(arpt_do_table); + +module_init(arp_tables_init); +module_exit(arp_tables_fini); |