ip6_tables.c

linux 内核源代码

					duprintf("mark_source_chains: bad "
						"negative verdict (%i)\n",
								t->verdict);
					return 0;
				}

				/* Return: backtrack through the last
				   big jump. */
				do {
					e->comefrom ^= (1<<NF_IP6_NUMHOOKS);
#ifdef DEBUG_IP_FIREWALL_USER
					if (e->comefrom
					    & (1 << NF_IP6_NUMHOOKS)) {
						duprintf("Back unset "
							 "on hook %u "
							 "rule %u\n",
							 hook, pos);
					}
#endif
					oldpos = pos;
					pos = e->counters.pcnt;
					e->counters.pcnt = 0;

					/* We're at the start. */
					if (pos == oldpos)
						goto next;

					e = (struct ip6t_entry *)
						(entry0 + pos);
				} while (oldpos == pos + e->next_offset);

				/* Move along one */
				size = e->next_offset;
				e = (struct ip6t_entry *)
					(entry0 + pos + size);
				e->counters.pcnt = pos;
				pos += size;
			} else {
				int newpos = t->verdict;

				if (strcmp(t->target.u.user.name,
					   IP6T_STANDARD_TARGET) == 0
				    && newpos >= 0) {
					if (newpos > newinfo->size -
						sizeof(struct ip6t_entry)) {
						duprintf("mark_source_chains: "
							"bad verdict (%i)\n",
								newpos);
						return 0;
					}
					/* This a jump; chase it. */
					duprintf("Jump rule %u -> %u\n",
						 pos, newpos);
				} else {
					/* ... this is a fallthru */
					newpos = pos + e->next_offset;
				}
				e = (struct ip6t_entry *)
					(entry0 + newpos);
				e->counters.pcnt = pos;
				pos = newpos;
			}
		}
		next:
		duprintf("Finished chain %u\n", hook);
	}
	return 1;
}

static inline int
cleanup_match(struct ip6t_entry_match *m, unsigned int *i)
{
	if (i && (*i)-- == 0)
		return 1;

	if (m->u.kernel.match->destroy)
		m->u.kernel.match->destroy(m->u.kernel.match, m->data);
	module_put(m->u.kernel.match->me);
	return 0;
}

static inline int
check_match(struct ip6t_entry_match *m,
	    const char *name,
	    const struct ip6t_ip6 *ipv6,
	    unsigned int hookmask,
	    unsigned int *i)
{
	struct xt_match *match;
	int ret;

	match = try_then_request_module(xt_find_match(AF_INET6, m->u.user.name,
					m->u.user.revision),
					"ip6t_%s", m->u.user.name);
	if (IS_ERR(match) || !match) {
		duprintf("check_match: `%s' not found\n", m->u.user.name);
		return match ? PTR_ERR(match) : -ENOENT;
	}
	m->u.kernel.match = match;

	ret = xt_check_match(match, AF_INET6, m->u.match_size - sizeof(*m),
			     name, hookmask, ipv6->proto,
			     ipv6->invflags & IP6T_INV_PROTO);
	if (ret)
		goto err;

	if (m->u.kernel.match->checkentry
	    && !m->u.kernel.match->checkentry(name, ipv6, match,  m->data,
					      hookmask)) {
		duprintf("ip_tables: check failed for `%s'.\n",
			 m->u.kernel.match->name);
		ret = -EINVAL;
		goto err;
	}

	(*i)++;
	return 0;
err:
	module_put(m->u.kernel.match->me);
	return ret;
}

static struct xt_target ip6t_standard_target;

static inline int
check_entry(struct ip6t_entry *e, const char *name, unsigned int size,
	    unsigned int *i)
{
	struct ip6t_entry_target *t;
	struct xt_target *target;
	int ret;
	unsigned int j;

	if (!ip6_checkentry(&e->ipv6)) {
		duprintf("ip_tables: ip check failed %p %s.\n", e, name);
		return -EINVAL;
	}

	if (e->target_offset + sizeof(struct ip6t_entry_target) >
								e->next_offset)
		return -EINVAL;

	j = 0;
	ret = IP6T_MATCH_ITERATE(e, check_match, name, &e->ipv6, e->comefrom, &j);
	if (ret != 0)
		goto cleanup_matches;

	t = ip6t_get_target(e);
	ret = -EINVAL;
	if (e->target_offset + t->u.target_size > e->next_offset)
			goto cleanup_matches;
	target = try_then_request_module(xt_find_target(AF_INET6,
							t->u.user.name,
							t->u.user.revision),
					 "ip6t_%s", t->u.user.name);
	if (IS_ERR(target) || !target) {
		duprintf("check_entry: `%s' not found\n", t->u.user.name);
		ret = target ? PTR_ERR(target) : -ENOENT;
		goto cleanup_matches;
	}
	t->u.kernel.target = target;

	ret = xt_check_target(target, AF_INET6, t->u.target_size - sizeof(*t),
			      name, e->comefrom, e->ipv6.proto,
			      e->ipv6.invflags & IP6T_INV_PROTO);
	if (ret)
		goto err;

	if (t->u.kernel.target->checkentry
		   && !t->u.kernel.target->checkentry(name, e, target, t->data,
						      e->comefrom)) {
		duprintf("ip_tables: check failed for `%s'.\n",
			 t->u.kernel.target->name);
		ret = -EINVAL;
		goto err;
	}

	(*i)++;
	return 0;
 err:
	module_put(t->u.kernel.target->me);
 cleanup_matches:
	IP6T_MATCH_ITERATE(e, cleanup_match, &j);
	return ret;
}

static inline int
check_entry_size_and_hooks(struct ip6t_entry *e,
			   struct xt_table_info *newinfo,
			   unsigned char *base,
			   unsigned char *limit,
			   const unsigned int *hook_entries,
			   const unsigned int *underflows,
			   unsigned int *i)
{
	unsigned int h;

	if ((unsigned long)e % __alignof__(struct ip6t_entry) != 0
	    || (unsigned char *)e + sizeof(struct ip6t_entry) >= limit) {
		duprintf("Bad offset %p\n", e);
		return -EINVAL;
	}

	if (e->next_offset
	    < sizeof(struct ip6t_entry) + sizeof(struct ip6t_entry_target)) {
		duprintf("checking: element %p size %u\n",
			 e, e->next_offset);
		return -EINVAL;
	}

	/* Check hooks & underflows */
	for (h = 0; h < NF_IP6_NUMHOOKS; h++) {
		if ((unsigned char *)e - base == hook_entries[h])
			newinfo->hook_entry[h] = hook_entries[h];
		if ((unsigned char *)e - base == underflows[h])
			newinfo->underflow[h] = underflows[h];
	}

	/* FIXME: underflows must be unconditional, standard verdicts
	   < 0 (not IP6T_RETURN). --RR */

	/* Clear counters and comefrom */
	e->counters = ((struct xt_counters) { 0, 0 });
	e->comefrom = 0;

	(*i)++;
	return 0;
}

static inline int
cleanup_entry(struct ip6t_entry *e, unsigned int *i)
{
	struct ip6t_entry_target *t;

	if (i && (*i)-- == 0)
		return 1;

	/* Cleanup all matches */
	IP6T_MATCH_ITERATE(e, cleanup_match, NULL);
	t = ip6t_get_target(e);
	if (t->u.kernel.target->destroy)
		t->u.kernel.target->destroy(t->u.kernel.target, t->data);
	module_put(t->u.kernel.target->me);
	return 0;
}

/* Checks and translates the user-supplied table segment (held in
   newinfo) */
static int
translate_table(const char *name,
		unsigned int valid_hooks,
		struct xt_table_info *newinfo,
		void *entry0,
		unsigned int size,
		unsigned int number,
		const unsigned int *hook_entries,
		const unsigned int *underflows)
{
	unsigned int i;
	int ret;

	newinfo->size = size;
	newinfo->number = number;

	/* Init all hooks to impossible value. */
	for (i = 0; i < NF_IP6_NUMHOOKS; i++) {
		newinfo->hook_entry[i] = 0xFFFFFFFF;
		newinfo->underflow[i] = 0xFFFFFFFF;
	}

	duprintf("translate_table: size %u\n", newinfo->size);
	i = 0;
	/* Walk through entries, checking offsets. */
	ret = IP6T_ENTRY_ITERATE(entry0, newinfo->size,
				check_entry_size_and_hooks,
				newinfo,
				entry0,
				entry0 + size,
				hook_entries, underflows, &i);
	if (ret != 0)
		return ret;

	if (i != number) {
		duprintf("translate_table: %u not %u entries\n",
			 i, number);
		return -EINVAL;
	}

	/* Check hooks all assigned */
	for (i = 0; i < NF_IP6_NUMHOOKS; i++) {
		/* Only hooks which are valid */
		if (!(valid_hooks & (1 << i)))
			continue;
		if (newinfo->hook_entry[i] == 0xFFFFFFFF) {
			duprintf("Invalid hook entry %u %u\n",
				 i, hook_entries[i]);
			return -EINVAL;
		}
		if (newinfo->underflow[i] == 0xFFFFFFFF) {
			duprintf("Invalid underflow %u %u\n",
				 i, underflows[i]);
			return -EINVAL;
		}
	}

	if (!mark_source_chains(newinfo, valid_hooks, entry0))
		return -ELOOP;

	/* Finally, each sanity check must pass */
	i = 0;
	ret = IP6T_ENTRY_ITERATE(entry0, newinfo->size,
				check_entry, name, size, &i);

	if (ret != 0) {
		IP6T_ENTRY_ITERATE(entry0, newinfo->size,
				   cleanup_entry, &i);
		return ret;
	}

	/* And one copy for every other CPU */
	for_each_possible_cpu(i) {
		if (newinfo->entries[i] && newinfo->entries[i] != entry0)
			memcpy(newinfo->entries[i], entry0, newinfo->size);
	}

	return 0;
}

/* Gets counters. */
static inline int
add_entry_to_counter(const struct ip6t_entry *e,
		     struct xt_counters total[],
		     unsigned int *i)
{
	ADD_COUNTER(total[*i], e->counters.bcnt, e->counters.pcnt);

	(*i)++;
	return 0;
}

static inline int
set_entry_to_counter(const struct ip6t_entry *e,
		     struct ip6t_counters total[],
		     unsigned int *i)
{
	SET_COUNTER(total[*i], e->counters.bcnt, e->counters.pcnt);

	(*i)++;
	return 0;
}

static void
get_counters(const struct xt_table_info *t,
	     struct xt_counters counters[])
{
	unsigned int cpu;
	unsigned int i;
	unsigned int curcpu;

	/* Instead of clearing (by a previous call to memset())
	 * the counters and using adds, we set the counters
	 * with data used by 'current' CPU
	 * We dont care about preemption here.
	 */
	curcpu = raw_smp_processor_id();

	i = 0;
	IP6T_ENTRY_ITERATE(t->entries[curcpu],
			   t->size,
			   set_entry_to_counter,
			   counters,
			   &i);

	for_each_possible_cpu(cpu) {
		if (cpu == curcpu)
			continue;
		i = 0;
		IP6T_ENTRY_ITERATE(t->entries[cpu],
				  t->size,
				  add_entry_to_counter,
				  counters,
				  &i);
	}
}

static int
copy_entries_to_user(unsigned int total_size,
		     struct xt_table *table,
		     void __user *userptr)
{
	unsigned int off, num, countersize;
	struct ip6t_entry *e;
	struct xt_counters *counters;
	struct xt_table_info *private = table->private;
	int ret = 0;
	void *loc_cpu_entry;

	/* 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 = vmalloc(countersize);

	if (counters == NULL)
		return -ENOMEM;

	/* First, sum counters... */
	write_lock_bh(&table->lock);
	get_counters(private, counters);
	write_unlock_bh(&table->lock);

	/* choose the copy that is on ourc node/cpu */
	loc_cpu_entry = private->entries[raw_smp_processor_id()];
	if (copy_to_user(userptr, loc_cpu_entry, total_size) != 0) {
		ret = -EFAULT;
		goto free_counters;
	}

	/* 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++){
		unsigned int i;
		struct ip6t_entry_match *m;
		struct ip6t_entry_target *t;

		e = (struct ip6t_entry *)(loc_cpu_entry + off);
		if (copy_to_user(userptr + off
				 + offsetof(struct ip6t_entry, counters),
				 &counters[num],
				 sizeof(counters[num])) != 0) {
			ret = -EFAULT;
			goto free_counters;
		}

		for (i = sizeof(struct ip6t_entry);
		     i < e->target_offset;
		     i += m->u.match_size) {
			m = (void *)e + i;

			if (copy_to_user(userptr + off + i
					 + offsetof(struct ip6t_entry_match,
						    u.user.name),
					 m->u.kernel.match->name,
					 strlen(m->u.kernel.match->name)+1)
			    != 0) {
				ret = -EFAULT;
				goto free_counters;
			}
		}

		t = ip6t_get_target(e);
		if (copy_to_user(userptr + off + e->target_offset
				 + offsetof(struct ip6t_entry_target,
					    u.user.name),
				 t->u.kernel.target->name,
				 strlen(t->u.kernel.target->name)+1) != 0) {
			ret = -EFAULT;
			goto free_counters;
		}
	}

 free_counters:
	vfree(counters);
	return ret;
}

static int
get_entries(const struct ip6t_get_entries *entries,
	    struct ip6t_get_entries __user *uptr)
{
	int ret;
	struct xt_table *t;

	t = xt_find_table_lock(AF_INET6, entries->name);
	if (t && !IS_ERR(t)) {
		struct xt_table_info *private = t->private;
		duprintf("t->private->number = %u\n", private->number);
		if (entries->size == private->size)
			ret = copy_entries_to_user(private->size,
						   t, uptr->entrytable);
		else {
			duprintf("get_entries: I've got %u not %u!\n",
				 private->size, entries->size);
			ret = -EINVAL;
		}
		module_put(t->me);
		xt_table_unlock(t);
	} else
		ret = t ? PTR_ERR(t) : -ENOENT;

	return ret;
}

static int
do_replace(void __user *user, unsigned int len)
{
	int ret;
	struct ip6t_replace tmp;
	struct xt_table *t;
	struct xt_table_info *newinfo, *oldinfo;
	struct xt_counters *counters;
	void *loc_cpu_entry, *loc_cpu_old_entry;

	if (copy_from_user(&tmp, user, sizeof(tmp)) != 0)
		return -EFAULT;

	/* overflow check */
	if (tmp.size >= (INT_MAX - sizeof(struct xt_table_info)) / NR_CPUS -
			SMP_CACHE_BYTES)
		return -ENOMEM;
	if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
		return -ENOMEM;

	newinfo = xt_alloc_table_info(tmp.size);
	if (!newinfo)
		return -ENOMEM;

	/* choose the copy that is on our node/cpu */
	loc_cpu_entry = newinfo->entries[raw_smp_processor_id()];
	if (copy_from_user(loc_cpu_entry, user + sizeof(tmp),
			   tmp.size) != 0) {
		ret = -EFAULT;
		goto free_newinfo;
	}

	counters = vmalloc(tmp.num_counters * sizeof(struct xt_counters));
	if (!counters) {
		ret = -ENOMEM;
		goto free_newinfo;
	}

	ret = translate_table(tmp.name, tmp.valid_hooks,
			      newinfo, loc_cpu_entry, tmp.size, tmp.num_entries,
			      tmp.hook_entry, tmp.underflow);
	if (ret != 0)
		goto free_newinfo_counters;