[net-next-2.6.git] / net / core / filter.c

/*
 * Linux Socket Filter - Kernel level socket filtering
 *
 * Author:
 *     Jay Schulist <jschlst@samba.org>
 *
 * Based on the design of:
 *     - The Berkeley Packet Filter
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 *
 * Andi Kleen - Fix a few bad bugs and races.
 * Kris Katterjohn - Added many additional checks in sk_chk_filter()
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/mm.h>
#include <linux/fcntl.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/if_packet.h>
#include <net/ip.h>
#include <net/protocol.h>
#include <net/netlink.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <linux/errno.h>
#include <linux/timer.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/unaligned.h>
#include <linux/filter.h>

/* No hurry in this branch */
static void *__load_pointer(struct sk_buff *skb, int k)
{
	u8 *ptr = NULL;

	if (k >= SKF_NET_OFF)
		ptr = skb_network_header(skb) + k - SKF_NET_OFF;
	else if (k >= SKF_LL_OFF)
		ptr = skb_mac_header(skb) + k - SKF_LL_OFF;

	if (ptr >= skb->head && ptr < skb_tail_pointer(skb))
		return ptr;
	return NULL;
}

static inline void *load_pointer(struct sk_buff *skb, int k,
				 unsigned int size, void *buffer)
{
	if (k >= 0)
		return skb_header_pointer(skb, k, size, buffer);
	else {
		if (k >= SKF_AD_OFF)
			return NULL;
		return __load_pointer(skb, k);
	}
}

/**
 *	sk_filter - run a packet through a socket filter
 *	@sk: sock associated with &sk_buff
 *	@skb: buffer to filter
 *
 * Run the filter code and then cut skb->data to correct size returned by
 * sk_run_filter. If pkt_len is 0 we toss packet. If skb->len is smaller
 * than pkt_len we keep whole skb->data. This is the socket level
 * wrapper to sk_run_filter. It returns 0 if the packet should
 * be accepted or -EPERM if the packet should be tossed.
 *
 */
int sk_filter(struct sock *sk, struct sk_buff *skb)
{
	int err;
	struct sk_filter *filter;

	err = security_sock_rcv_skb(sk, skb);
	if (err)
		return err;

	rcu_read_lock_bh();
	filter = rcu_dereference_bh(sk->sk_filter);
	if (filter) {
		unsigned int pkt_len = sk_run_filter(skb, filter->insns,
				filter->len);
		err = pkt_len ? pskb_trim(skb, pkt_len) : -EPERM;
	}
	rcu_read_unlock_bh();

	return err;
}
EXPORT_SYMBOL(sk_filter);

/**
 *	sk_run_filter - run a filter on a socket
 *	@skb: buffer to run the filter on
 *	@filter: filter to apply
 *	@flen: length of filter
 *
 * Decode and apply filter instructions to the skb->data.
 * Return length to keep, 0 for none. skb is the data we are
 * filtering, filter is the array of filter instructions, and
 * len is the number of filter blocks in the array.
 */
unsigned int sk_run_filter(struct sk_buff *skb, struct sock_filter *filter, int flen)
{
	struct sock_filter *fentry;	/* We walk down these */
	void *ptr;
	u32 A = 0;			/* Accumulator */
	u32 X = 0;			/* Index Register */
	u32 mem[BPF_MEMWORDS];		/* Scratch Memory Store */
	u32 tmp;
	int k;
	int pc;

	/*
	 * Process array of filter instructions.
	 */
	for (pc = 0; pc < flen; pc++) {
		fentry = &filter[pc];

		switch (fentry->code) {
		case BPF_ALU|BPF_ADD|BPF_X:
			A += X;
			continue;
		case BPF_ALU|BPF_ADD|BPF_K:
			A += fentry->k;
			continue;
		case BPF_ALU|BPF_SUB|BPF_X:
			A -= X;
			continue;
		case BPF_ALU|BPF_SUB|BPF_K:
			A -= fentry->k;
			continue;
		case BPF_ALU|BPF_MUL|BPF_X:
			A *= X;
			continue;
		case BPF_ALU|BPF_MUL|BPF_K:
			A *= fentry->k;
			continue;
		case BPF_ALU|BPF_DIV|BPF_X:
			if (X == 0)
				return 0;
			A /= X;
			continue;
		case BPF_ALU|BPF_DIV|BPF_K:
			A /= fentry->k;
			continue;
		case BPF_ALU|BPF_AND|BPF_X:
			A &= X;
			continue;
		case BPF_ALU|BPF_AND|BPF_K:
			A &= fentry->k;
			continue;
		case BPF_ALU|BPF_OR|BPF_X:
			A |= X;
			continue;
		case BPF_ALU|BPF_OR|BPF_K:
			A |= fentry->k;
			continue;
		case BPF_ALU|BPF_LSH|BPF_X:
			A <<= X;
			continue;
		case BPF_ALU|BPF_LSH|BPF_K:
			A <<= fentry->k;
			continue;
		case BPF_ALU|BPF_RSH|BPF_X:
			A >>= X;
			continue;
		case BPF_ALU|BPF_RSH|BPF_K:
			A >>= fentry->k;
			continue;
		case BPF_ALU|BPF_NEG:
			A = -A;
			continue;
		case BPF_JMP|BPF_JA:
			pc += fentry->k;
			continue;
		case BPF_JMP|BPF_JGT|BPF_K:
			pc += (A > fentry->k) ? fentry->jt : fentry->jf;
			continue;
		case BPF_JMP|BPF_JGE|BPF_K:
			pc += (A >= fentry->k) ? fentry->jt : fentry->jf;
			continue;
		case BPF_JMP|BPF_JEQ|BPF_K:
			pc += (A == fentry->k) ? fentry->jt : fentry->jf;
			continue;
		case BPF_JMP|BPF_JSET|BPF_K:
			pc += (A & fentry->k) ? fentry->jt : fentry->jf;
			continue;
		case BPF_JMP|BPF_JGT|BPF_X:
			pc += (A > X) ? fentry->jt : fentry->jf;
			continue;
		case BPF_JMP|BPF_JGE|BPF_X:
			pc += (A >= X) ? fentry->jt : fentry->jf;
			continue;
		case BPF_JMP|BPF_JEQ|BPF_X:
			pc += (A == X) ? fentry->jt : fentry->jf;
			continue;
		case BPF_JMP|BPF_JSET|BPF_X:
			pc += (A & X) ? fentry->jt : fentry->jf;
			continue;
		case BPF_LD|BPF_W|BPF_ABS:
			k = fentry->k;
load_w:
			ptr = load_pointer(skb, k, 4, &tmp);
			if (ptr != NULL) {
				A = get_unaligned_be32(ptr);
				continue;
			}
			break;
		case BPF_LD|BPF_H|BPF_ABS:
			k = fentry->k;
load_h:
			ptr = load_pointer(skb, k, 2, &tmp);
			if (ptr != NULL) {
				A = get_unaligned_be16(ptr);
				continue;
			}
			break;
		case BPF_LD|BPF_B|BPF_ABS:
			k = fentry->k;
load_b:
			ptr = load_pointer(skb, k, 1, &tmp);
			if (ptr != NULL) {
				A = *(u8 *)ptr;
				continue;
			}
			break;
		case BPF_LD|BPF_W|BPF_LEN:
			A = skb->len;
			continue;
		case BPF_LDX|BPF_W|BPF_LEN:
			X = skb->len;
			continue;
		case BPF_LD|BPF_W|BPF_IND:
			k = X + fentry->k;
			goto load_w;
		case BPF_LD|BPF_H|BPF_IND:
			k = X + fentry->k;
			goto load_h;
		case BPF_LD|BPF_B|BPF_IND:
			k = X + fentry->k;
			goto load_b;
		case BPF_LDX|BPF_B|BPF_MSH:
			ptr = load_pointer(skb, fentry->k, 1, &tmp);
			if (ptr != NULL) {
				X = (*(u8 *)ptr & 0xf) << 2;
				continue;
			}
			return 0;
		case BPF_LD|BPF_IMM:
			A = fentry->k;
			continue;
		case BPF_LDX|BPF_IMM:
			X = fentry->k;
			continue;
		case BPF_LD|BPF_MEM:
			A = mem[fentry->k];
			continue;
		case BPF_LDX|BPF_MEM:
			X = mem[fentry->k];
			continue;
		case BPF_MISC|BPF_TAX:
			X = A;
			continue;
		case BPF_MISC|BPF_TXA:
			A = X;
			continue;
		case BPF_RET|BPF_K:
			return fentry->k;
		case BPF_RET|BPF_A:
			return A;
		case BPF_ST:
			mem[fentry->k] = A;
			continue;
		case BPF_STX:
			mem[fentry->k] = X;
			continue;
		default:
			WARN_ON(1);
			return 0;
		}

		/*
		 * Handle ancillary data, which are impossible
		 * (or very difficult) to get parsing packet contents.
		 */
		switch (k-SKF_AD_OFF) {
		case SKF_AD_PROTOCOL:
			A = ntohs(skb->protocol);
			continue;
		case SKF_AD_PKTTYPE:
			A = skb->pkt_type;
			continue;
		case SKF_AD_IFINDEX:
			A = skb->dev->ifindex;
			continue;
		case SKF_AD_MARK:
			A = skb->mark;
			continue;
		case SKF_AD_QUEUE:
			A = skb->queue_mapping;
			continue;
		case SKF_AD_NLATTR: {
			struct nlattr *nla;

			if (skb_is_nonlinear(skb))
				return 0;
			if (A > skb->len - sizeof(struct nlattr))
				return 0;

			nla = nla_find((struct nlattr *)&skb->data[A],
				       skb->len - A, X);
			if (nla)
				A = (void *)nla - (void *)skb->data;
			else
				A = 0;
			continue;
		}
		case SKF_AD_NLATTR_NEST: {
			struct nlattr *nla;

			if (skb_is_nonlinear(skb))
				return 0;
			if (A > skb->len - sizeof(struct nlattr))
				return 0;

			nla = (struct nlattr *)&skb->data[A];
			if (nla->nla_len > A - skb->len)
				return 0;

			nla = nla_find_nested(nla, X);
			if (nla)
				A = (void *)nla - (void *)skb->data;
			else
				A = 0;
			continue;
		}
		default:
			return 0;
		}
	}

	return 0;
}
EXPORT_SYMBOL(sk_run_filter);

/**
 *	sk_chk_filter - verify socket filter code
 *	@filter: filter to verify
 *	@flen: length of filter
 *
 * Check the user's filter code. If we let some ugly
 * filter code slip through kaboom! The filter must contain
 * no references or jumps that are out of range, no illegal
 * instructions, and must end with a RET instruction.
 *
 * All jumps are forward as they are not signed.
 *
 * Returns 0 if the rule set is legal or -EINVAL if not.
 */
int sk_chk_filter(struct sock_filter *filter, int flen)
{
	struct sock_filter *ftest;
	int pc;

	if (flen == 0 || flen > BPF_MAXINSNS)
		return -EINVAL;

	/* check the filter code now */
	for (pc = 0; pc < flen; pc++) {
		ftest = &filter[pc];

		/* Only allow valid instructions */
		switch (ftest->code) {
		case BPF_ALU|BPF_ADD|BPF_K:
		case BPF_ALU|BPF_ADD|BPF_X:
		case BPF_ALU|BPF_SUB|BPF_K:
		case BPF_ALU|BPF_SUB|BPF_X:
		case BPF_ALU|BPF_MUL|BPF_K:
		case BPF_ALU|BPF_MUL|BPF_X:
		case BPF_ALU|BPF_DIV|BPF_X:
		case BPF_ALU|BPF_AND|BPF_K:
		case BPF_ALU|BPF_AND|BPF_X:
		case BPF_ALU|BPF_OR|BPF_K:
		case BPF_ALU|BPF_OR|BPF_X:
		case BPF_ALU|BPF_LSH|BPF_K:
		case BPF_ALU|BPF_LSH|BPF_X:
		case BPF_ALU|BPF_RSH|BPF_K:
		case BPF_ALU|BPF_RSH|BPF_X:
		case BPF_ALU|BPF_NEG:
		case BPF_LD|BPF_W|BPF_ABS:
		case BPF_LD|BPF_H|BPF_ABS:
		case BPF_LD|BPF_B|BPF_ABS:
		case BPF_LD|BPF_W|BPF_LEN:
		case BPF_LD|BPF_W|BPF_IND:
		case BPF_LD|BPF_H|BPF_IND:
		case BPF_LD|BPF_B|BPF_IND:
		case BPF_LD|BPF_IMM:
		case BPF_LDX|BPF_W|BPF_LEN:
		case BPF_LDX|BPF_B|BPF_MSH:
		case BPF_LDX|BPF_IMM:
		case BPF_MISC|BPF_TAX:
		case BPF_MISC|BPF_TXA:
		case BPF_RET|BPF_K:
		case BPF_RET|BPF_A:
			break;

		/* Some instructions need special checks */

		case BPF_ALU|BPF_DIV|BPF_K:
			/* check for division by zero */
			if (ftest->k == 0)
				return -EINVAL;
			break;

		case BPF_LD|BPF_MEM:
		case BPF_LDX|BPF_MEM:
		case BPF_ST:
		case BPF_STX:
			/* check for invalid memory addresses */
			if (ftest->k >= BPF_MEMWORDS)
				return -EINVAL;
			break;

		case BPF_JMP|BPF_JA:
			/*
			 * Note, the large ftest->k might cause loops.
			 * Compare this with conditional jumps below,
			 * where offsets are limited. --ANK (981016)
			 */
			if (ftest->k >= (unsigned)(flen-pc-1))
				return -EINVAL;
			break;

		case BPF_JMP|BPF_JEQ|BPF_K:
		case BPF_JMP|BPF_JEQ|BPF_X:
		case BPF_JMP|BPF_JGE|BPF_K:
		case BPF_JMP|BPF_JGE|BPF_X:
		case BPF_JMP|BPF_JGT|BPF_K:
		case BPF_JMP|BPF_JGT|BPF_X:
		case BPF_JMP|BPF_JSET|BPF_K:
		case BPF_JMP|BPF_JSET|BPF_X:
			/* for conditionals both must be safe */
			if (pc + ftest->jt + 1 >= flen ||
			    pc + ftest->jf + 1 >= flen)
				return -EINVAL;
			break;

		default:
			return -EINVAL;
		}
	}

	return (BPF_CLASS(filter[flen - 1].code) == BPF_RET) ? 0 : -EINVAL;
}
EXPORT_SYMBOL(sk_chk_filter);

/**
 * 	sk_filter_rcu_release: Release a socket filter by rcu_head
 *	@rcu: rcu_head that contains the sk_filter to free
 */
static void sk_filter_rcu_release(struct rcu_head *rcu)
{
	struct sk_filter *fp = container_of(rcu, struct sk_filter, rcu);

	sk_filter_release(fp);
}

static void sk_filter_delayed_uncharge(struct sock *sk, struct sk_filter *fp)
{
	unsigned int size = sk_filter_len(fp);

	atomic_sub(size, &sk->sk_omem_alloc);
	call_rcu_bh(&fp->rcu, sk_filter_rcu_release);
}

/**
 *	sk_attach_filter - attach a socket filter
 *	@fprog: the filter program
 *	@sk: the socket to use
 *
 * Attach the user's filter code. We first run some sanity checks on
 * it to make sure it does not explode on us later. If an error
 * occurs or there is insufficient memory for the filter a negative
 * errno code is returned. On success the return is zero.
 */
int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk)
{
	struct sk_filter *fp, *old_fp;
	unsigned int fsize = sizeof(struct sock_filter) * fprog->len;
	int err;

	/* Make sure new filter is there and in the right amounts. */
	if (fprog->filter == NULL)
		return -EINVAL;

	fp = sock_kmalloc(sk, fsize+sizeof(*fp), GFP_KERNEL);
	if (!fp)
		return -ENOMEM;
	if (copy_from_user(fp->insns, fprog->filter, fsize)) {
		sock_kfree_s(sk, fp, fsize+sizeof(*fp));
		return -EFAULT;
	}

	atomic_set(&fp->refcnt, 1);
	fp->len = fprog->len;

	err = sk_chk_filter(fp->insns, fp->len);
	if (err) {
		sk_filter_uncharge(sk, fp);
		return err;
	}

	rcu_read_lock_bh();
	old_fp = rcu_dereference_bh(sk->sk_filter);
	rcu_assign_pointer(sk->sk_filter, fp);
	rcu_read_unlock_bh();

	if (old_fp)
		sk_filter_delayed_uncharge(sk, old_fp);
	return 0;
}
EXPORT_SYMBOL_GPL(sk_attach_filter);

int sk_detach_filter(struct sock *sk)
{
	int ret = -ENOENT;
	struct sk_filter *filter;

	rcu_read_lock_bh();
	filter = rcu_dereference_bh(sk->sk_filter);
	if (filter) {
		rcu_assign_pointer(sk->sk_filter, NULL);
		sk_filter_delayed_uncharge(sk, filter);
		ret = 0;
	}
	rcu_read_unlock_bh();
	return ret;
}
EXPORT_SYMBOL_GPL(sk_detach_filter);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* Linux Socket Filter - Kernel level socket filtering
	3	*
	4	* Author:
	5	* Jay Schulist <jschlst@samba.org>
	6	*
	7	* Based on the design of:
	8	* - The Berkeley Packet Filter
	9	*
	10	* This program is free software; you can redistribute it and/or
	11	* modify it under the terms of the GNU General Public License
	12	* as published by the Free Software Foundation; either version
	13	* 2 of the License, or (at your option) any later version.
	14	*
	15	* Andi Kleen - Fix a few bad bugs and races.
93699863	16	* Kris Katterjohn - Added many additional checks in sk_chk_filter()
1da177e4 LT	17	*/
	18
	19	#include <linux/module.h>
	20	#include <linux/types.h>
1da177e4 LT	21	#include <linux/mm.h>
	22	#include <linux/fcntl.h>
	23	#include <linux/socket.h>
	24	#include <linux/in.h>
	25	#include <linux/inet.h>
	26	#include <linux/netdevice.h>
	27	#include <linux/if_packet.h>
	28	#include <net/ip.h>
	29	#include <net/protocol.h>
4738c1db	30	#include <net/netlink.h>
1da177e4 LT	31	#include <linux/skbuff.h>
	32	#include <net/sock.h>
	33	#include <linux/errno.h>
	34	#include <linux/timer.h>
	35	#include <asm/system.h>
	36	#include <asm/uaccess.h>
40daafc8	37	#include <asm/unaligned.h>
1da177e4 LT	38	#include <linux/filter.h>
	39
	40	/* No hurry in this branch */
0b05b2a4	41	static void __load_pointer(struct sk_buff skb, int k)
1da177e4 LT	42	{
	43	u8 *ptr = NULL;
	44
	45	if (k >= SKF_NET_OFF)
d56f90a7	46	ptr = skb_network_header(skb) + k - SKF_NET_OFF;
1da177e4	47	else if (k >= SKF_LL_OFF)
98e399f8	48	ptr = skb_mac_header(skb) + k - SKF_LL_OFF;
1da177e4	49
27a884dc	50	if (ptr >= skb->head && ptr < skb_tail_pointer(skb))
1da177e4 LT	51	return ptr;
	52	return NULL;
	53	}
	54
0b05b2a4	55	static inline void load_pointer(struct sk_buff skb, int k,
4ec93edb	56	unsigned int size, void *buffer)
0b05b2a4 PM	57	{
	58	if (k >= 0)
	59	return skb_header_pointer(skb, k, size, buffer);
	60	else {
	61	if (k >= SKF_AD_OFF)
	62	return NULL;
	63	return __load_pointer(skb, k);
	64	}
	65	}
	66
43db6d65 SH	67	/**
	68	* sk_filter - run a packet through a socket filter
	69	* @sk: sock associated with &sk_buff
	70	* @skb: buffer to filter
43db6d65 SH	71	*
	72	* Run the filter code and then cut skb->data to correct size returned by
	73	* sk_run_filter. If pkt_len is 0 we toss packet. If skb->len is smaller
	74	* than pkt_len we keep whole skb->data. This is the socket level
	75	* wrapper to sk_run_filter. It returns 0 if the packet should
	76	* be accepted or -EPERM if the packet should be tossed.
	77	*
	78	*/
	79	int sk_filter(struct sock sk, struct sk_buff skb)
	80	{
	81	int err;
	82	struct sk_filter *filter;
	83
	84	err = security_sock_rcv_skb(sk, skb);
	85	if (err)
	86	return err;
	87
	88	rcu_read_lock_bh();
a898def2	89	filter = rcu_dereference_bh(sk->sk_filter);
43db6d65 SH	90	if (filter) {
	91	unsigned int pkt_len = sk_run_filter(skb, filter->insns,
	92	filter->len);
	93	err = pkt_len ? pskb_trim(skb, pkt_len) : -EPERM;
	94	}
	95	rcu_read_unlock_bh();
	96
	97	return err;
	98	}
	99	EXPORT_SYMBOL(sk_filter);
	100
1da177e4	101	/**
2966b66c	102	* sk_run_filter - run a filter on a socket
1da177e4 LT	103	* @skb: buffer to run the filter on
	104	* @filter: filter to apply
	105	* @flen: length of filter
	106	*
	107	* Decode and apply filter instructions to the skb->data.
	108	* Return length to keep, 0 for none. skb is the data we are
	109	* filtering, filter is the array of filter instructions, and
	110	* len is the number of filter blocks in the array.
	111	*/
4bad4dc9	112	unsigned int sk_run_filter(struct sk_buff skb, struct sock_filter filter, int flen)
1da177e4	113	{
1da177e4	114	struct sock_filter fentry; / We walk down these */
0b05b2a4	115	void *ptr;
2966b66c KK	116	u32 A = 0; /* Accumulator */
2966b66c KK	117	u32 X = 0; /* Index Register */
1da177e4	118	u32 mem[BPF_MEMWORDS]; /* Scratch Memory Store */
0b05b2a4	119	u32 tmp;
1da177e4 LT	120	int k;
	121	int pc;
	122
	123	/*
	124	* Process array of filter instructions.
	125	*/
	126	for (pc = 0; pc < flen; pc++) {
	127	fentry = &filter[pc];
4ec93edb	128
1da177e4 LT	129	switch (fentry->code) {
	130	case BPF_ALU\|BPF_ADD\|BPF_X:
	131	A += X;
	132	continue;
	133	case BPF_ALU\|BPF_ADD\|BPF_K:
	134	A += fentry->k;
	135	continue;
	136	case BPF_ALU\|BPF_SUB\|BPF_X:
	137	A -= X;
	138	continue;
	139	case BPF_ALU\|BPF_SUB\|BPF_K:
	140	A -= fentry->k;
	141	continue;
	142	case BPF_ALU\|BPF_MUL\|BPF_X:
	143	A *= X;
	144	continue;
	145	case BPF_ALU\|BPF_MUL\|BPF_K:
	146	A *= fentry->k;
	147	continue;
	148	case BPF_ALU\|BPF_DIV\|BPF_X:
	149	if (X == 0)
	150	return 0;
	151	A /= X;
	152	continue;
	153	case BPF_ALU\|BPF_DIV\|BPF_K:
1da177e4 LT	154	A /= fentry->k;
	155	continue;
	156	case BPF_ALU\|BPF_AND\|BPF_X:
	157	A &= X;
	158	continue;
	159	case BPF_ALU\|BPF_AND\|BPF_K:
	160	A &= fentry->k;
	161	continue;
	162	case BPF_ALU\|BPF_OR\|BPF_X:
	163	A \|= X;
	164	continue;
	165	case BPF_ALU\|BPF_OR\|BPF_K:
	166	A \|= fentry->k;
	167	continue;
	168	case BPF_ALU\|BPF_LSH\|BPF_X:
	169	A <<= X;
	170	continue;
	171	case BPF_ALU\|BPF_LSH\|BPF_K:
	172	A <<= fentry->k;
	173	continue;
	174	case BPF_ALU\|BPF_RSH\|BPF_X:
	175	A >>= X;
	176	continue;
	177	case BPF_ALU\|BPF_RSH\|BPF_K:
	178	A >>= fentry->k;
	179	continue;
	180	case BPF_ALU\|BPF_NEG:
	181	A = -A;
	182	continue;
	183	case BPF_JMP\|BPF_JA:
	184	pc += fentry->k;
	185	continue;
	186	case BPF_JMP\|BPF_JGT\|BPF_K:
	187	pc += (A > fentry->k) ? fentry->jt : fentry->jf;
	188	continue;
	189	case BPF_JMP\|BPF_JGE\|BPF_K:
	190	pc += (A >= fentry->k) ? fentry->jt : fentry->jf;
	191	continue;
	192	case BPF_JMP\|BPF_JEQ\|BPF_K:
	193	pc += (A == fentry->k) ? fentry->jt : fentry->jf;
	194	continue;
	195	case BPF_JMP\|BPF_JSET\|BPF_K:
	196	pc += (A & fentry->k) ? fentry->jt : fentry->jf;
	197	continue;
	198	case BPF_JMP\|BPF_JGT\|BPF_X:
	199	pc += (A > X) ? fentry->jt : fentry->jf;
	200	continue;
	201	case BPF_JMP\|BPF_JGE\|BPF_X:
	202	pc += (A >= X) ? fentry->jt : fentry->jf;
	203	continue;
	204	case BPF_JMP\|BPF_JEQ\|BPF_X:
	205	pc += (A == X) ? fentry->jt : fentry->jf;
	206	continue;
	207	case BPF_JMP\|BPF_JSET\|BPF_X:
	208	pc += (A & X) ? fentry->jt : fentry->jf;
	209	continue;
	210	case BPF_LD\|BPF_W\|BPF_ABS:
	211	k = fentry->k;
e35bedf3	212	load_w:
0b05b2a4 PM	213	ptr = load_pointer(skb, k, 4, &tmp);
0b05b2a4 PM	214	if (ptr != NULL) {
d3e2ce3b	215	A = get_unaligned_be32(ptr);
0b05b2a4	216	continue;
1da177e4	217	}
1198ad00	218	break;
1da177e4 LT	219	case BPF_LD\|BPF_H\|BPF_ABS:
1da177e4 LT	220	k = fentry->k;
e35bedf3	221	load_h:
0b05b2a4 PM	222	ptr = load_pointer(skb, k, 2, &tmp);
0b05b2a4 PM	223	if (ptr != NULL) {
d3e2ce3b	224	A = get_unaligned_be16(ptr);
0b05b2a4	225	continue;
1da177e4	226	}
1198ad00	227	break;
1da177e4 LT	228	case BPF_LD\|BPF_B\|BPF_ABS:
	229	k = fentry->k;
	230	load_b:
0b05b2a4 PM	231	ptr = load_pointer(skb, k, 1, &tmp);
	232	if (ptr != NULL) {
	233	A = (u8 )ptr;
	234	continue;
1da177e4	235	}
1198ad00	236	break;
1da177e4	237	case BPF_LD\|BPF_W\|BPF_LEN:
3154e540	238	A = skb->len;
1da177e4 LT	239	continue;
1da177e4 LT	240	case BPF_LDX\|BPF_W\|BPF_LEN:
3154e540	241	X = skb->len;
1da177e4 LT	242	continue;
	243	case BPF_LD\|BPF_W\|BPF_IND:
	244	k = X + fentry->k;
	245	goto load_w;
	246	case BPF_LD\|BPF_H\|BPF_IND:
	247	k = X + fentry->k;
	248	goto load_h;
	249	case BPF_LD\|BPF_B\|BPF_IND:
	250	k = X + fentry->k;
	251	goto load_b;
	252	case BPF_LDX\|BPF_B\|BPF_MSH:
0b05b2a4 PM	253	ptr = load_pointer(skb, fentry->k, 1, &tmp);
	254	if (ptr != NULL) {
	255	X = ((u8 )ptr & 0xf) << 2;
	256	continue;
	257	}
	258	return 0;
1da177e4 LT	259	case BPF_LD\|BPF_IMM:
	260	A = fentry->k;
	261	continue;
	262	case BPF_LDX\|BPF_IMM:
	263	X = fentry->k;
	264	continue;
	265	case BPF_LD\|BPF_MEM:
	266	A = mem[fentry->k];
	267	continue;
	268	case BPF_LDX\|BPF_MEM:
	269	X = mem[fentry->k];
	270	continue;
	271	case BPF_MISC\|BPF_TAX:
	272	X = A;
	273	continue;
	274	case BPF_MISC\|BPF_TXA:
	275	A = X;
	276	continue;
	277	case BPF_RET\|BPF_K:
4bad4dc9	278	return fentry->k;
1da177e4	279	case BPF_RET\|BPF_A:
4bad4dc9	280	return A;
1da177e4 LT	281	case BPF_ST:
	282	mem[fentry->k] = A;
	283	continue;
	284	case BPF_STX:
	285	mem[fentry->k] = X;
	286	continue;
	287	default:
93699863	288	WARN_ON(1);
1da177e4 LT	289	return 0;
	290	}
	291
	292	/*
	293	* Handle ancillary data, which are impossible
	294	* (or very difficult) to get parsing packet contents.
	295	*/
	296	switch (k-SKF_AD_OFF) {
	297	case SKF_AD_PROTOCOL:
252e3346	298	A = ntohs(skb->protocol);
1da177e4 LT	299	continue;
	300	case SKF_AD_PKTTYPE:
	301	A = skb->pkt_type;
	302	continue;
	303	case SKF_AD_IFINDEX:
	304	A = skb->dev->ifindex;
	305	continue;
7e75f93e	306	case SKF_AD_MARK:
	307	A = skb->mark;
	308	continue;
d19742fb ED	309	case SKF_AD_QUEUE:
	310	A = skb->queue_mapping;
	311	continue;
4738c1db PM	312	case SKF_AD_NLATTR: {
	313	struct nlattr *nla;
	314
	315	if (skb_is_nonlinear(skb))
	316	return 0;
	317	if (A > skb->len - sizeof(struct nlattr))
	318	return 0;
	319
	320	nla = nla_find((struct nlattr *)&skb->data[A],
	321	skb->len - A, X);
	322	if (nla)
	323	A = (void )nla - (void )skb->data;
	324	else
	325	A = 0;
	326	continue;
	327	}
d214c753 PNA	328	case SKF_AD_NLATTR_NEST: {
	329	struct nlattr *nla;
	330
	331	if (skb_is_nonlinear(skb))
	332	return 0;
	333	if (A > skb->len - sizeof(struct nlattr))
	334	return 0;
	335
	336	nla = (struct nlattr *)&skb->data[A];
	337	if (nla->nla_len > A - skb->len)
	338	return 0;
	339
	340	nla = nla_find_nested(nla, X);
	341	if (nla)
	342	A = (void )nla - (void )skb->data;
	343	else
	344	A = 0;
	345	continue;
	346	}
1da177e4 LT	347	default:
	348	return 0;
	349	}
	350	}
	351
	352	return 0;
	353	}
b715631f	354	EXPORT_SYMBOL(sk_run_filter);
1da177e4 LT	355
	356	/**
	357	* sk_chk_filter - verify socket filter code
	358	* @filter: filter to verify
	359	* @flen: length of filter
	360	*
	361	* Check the user's filter code. If we let some ugly
	362	* filter code slip through kaboom! The filter must contain
93699863 KK	363	* no references or jumps that are out of range, no illegal
93699863 KK	364	* instructions, and must end with a RET instruction.
1da177e4	365	*
7b11f69f KK	366	* All jumps are forward as they are not signed.
	367	*
	368	* Returns 0 if the rule set is legal or -EINVAL if not.
1da177e4 LT	369	*/
	370	int sk_chk_filter(struct sock_filter *filter, int flen)
	371	{
	372	struct sock_filter *ftest;
	373	int pc;
	374
1b93ae64	375	if (flen == 0 \|\| flen > BPF_MAXINSNS)
1da177e4 LT	376	return -EINVAL;
	377
	378	/* check the filter code now */
	379	for (pc = 0; pc < flen; pc++) {
1da177e4	380	ftest = &filter[pc];
1da177e4	381
93699863 KK	382	/* Only allow valid instructions */
	383	switch (ftest->code) {
	384	case BPF_ALU\|BPF_ADD\|BPF_K:
	385	case BPF_ALU\|BPF_ADD\|BPF_X:
	386	case BPF_ALU\|BPF_SUB\|BPF_K:
	387	case BPF_ALU\|BPF_SUB\|BPF_X:
	388	case BPF_ALU\|BPF_MUL\|BPF_K:
	389	case BPF_ALU\|BPF_MUL\|BPF_X:
	390	case BPF_ALU\|BPF_DIV\|BPF_X:
	391	case BPF_ALU\|BPF_AND\|BPF_K:
	392	case BPF_ALU\|BPF_AND\|BPF_X:
	393	case BPF_ALU\|BPF_OR\|BPF_K:
	394	case BPF_ALU\|BPF_OR\|BPF_X:
	395	case BPF_ALU\|BPF_LSH\|BPF_K:
	396	case BPF_ALU\|BPF_LSH\|BPF_X:
	397	case BPF_ALU\|BPF_RSH\|BPF_K:
	398	case BPF_ALU\|BPF_RSH\|BPF_X:
	399	case BPF_ALU\|BPF_NEG:
	400	case BPF_LD\|BPF_W\|BPF_ABS:
	401	case BPF_LD\|BPF_H\|BPF_ABS:
	402	case BPF_LD\|BPF_B\|BPF_ABS:
	403	case BPF_LD\|BPF_W\|BPF_LEN:
	404	case BPF_LD\|BPF_W\|BPF_IND:
	405	case BPF_LD\|BPF_H\|BPF_IND:
	406	case BPF_LD\|BPF_B\|BPF_IND:
	407	case BPF_LD\|BPF_IMM:
	408	case BPF_LDX\|BPF_W\|BPF_LEN:
	409	case BPF_LDX\|BPF_B\|BPF_MSH:
	410	case BPF_LDX\|BPF_IMM:
	411	case BPF_MISC\|BPF_TAX:
	412	case BPF_MISC\|BPF_TXA:
	413	case BPF_RET\|BPF_K:
	414	case BPF_RET\|BPF_A:
	415	break;
	416
	417	/* Some instructions need special checks */
fb0d366b	418
93699863 KK	419	case BPF_ALU\|BPF_DIV\|BPF_K:
	420	/* check for division by zero */
	421	if (ftest->k == 0)
1da177e4	422	return -EINVAL;
93699863 KK	423	break;
	424
	425	case BPF_LD\|BPF_MEM:
	426	case BPF_LDX\|BPF_MEM:
	427	case BPF_ST:
	428	case BPF_STX:
	429	/* check for invalid memory addresses */
	430	if (ftest->k >= BPF_MEMWORDS)
	431	return -EINVAL;
	432	break;
	433
	434	case BPF_JMP\|BPF_JA:
	435	/*
	436	* Note, the large ftest->k might cause loops.
	437	* Compare this with conditional jumps below,
	438	* where offsets are limited. --ANK (981016)
	439	*/
	440	if (ftest->k >= (unsigned)(flen-pc-1))
	441	return -EINVAL;
	442	break;
	443
	444	case BPF_JMP\|BPF_JEQ\|BPF_K:
	445	case BPF_JMP\|BPF_JEQ\|BPF_X:
	446	case BPF_JMP\|BPF_JGE\|BPF_K:
	447	case BPF_JMP\|BPF_JGE\|BPF_X:
	448	case BPF_JMP\|BPF_JGT\|BPF_K:
	449	case BPF_JMP\|BPF_JGT\|BPF_X:
	450	case BPF_JMP\|BPF_JSET\|BPF_K:
	451	case BPF_JMP\|BPF_JSET\|BPF_X:
	452	/* for conditionals both must be safe */
e35bedf3	453	if (pc + ftest->jt + 1 >= flen \|\|
93699863 KK	454	pc + ftest->jf + 1 >= flen)
	455	return -EINVAL;
	456	break;
	457
	458	default:
	459	return -EINVAL;
1da177e4 LT	460	}
	461	}
	462
e35bedf3	463	return (BPF_CLASS(filter[flen - 1].code) == BPF_RET) ? 0 : -EINVAL;
1da177e4	464	}
b715631f	465	EXPORT_SYMBOL(sk_chk_filter);
1da177e4	466
47e958ea PE	467	/**
	468	* sk_filter_rcu_release: Release a socket filter by rcu_head
	469	* @rcu: rcu_head that contains the sk_filter to free
	470	*/
	471	static void sk_filter_rcu_release(struct rcu_head *rcu)
	472	{
	473	struct sk_filter *fp = container_of(rcu, struct sk_filter, rcu);
	474
	475	sk_filter_release(fp);
	476	}
	477
	478	static void sk_filter_delayed_uncharge(struct sock sk, struct sk_filter fp)
	479	{
	480	unsigned int size = sk_filter_len(fp);
	481
	482	atomic_sub(size, &sk->sk_omem_alloc);
	483	call_rcu_bh(&fp->rcu, sk_filter_rcu_release);
	484	}
	485
1da177e4 LT	486	/**
	487	* sk_attach_filter - attach a socket filter
	488	* @fprog: the filter program
	489	* @sk: the socket to use
	490	*
	491	* Attach the user's filter code. We first run some sanity checks on
	492	* it to make sure it does not explode on us later. If an error
	493	* occurs or there is insufficient memory for the filter a negative
	494	* errno code is returned. On success the return is zero.
	495	*/
	496	int sk_attach_filter(struct sock_fprog fprog, struct sock sk)
	497	{
d3904b73	498	struct sk_filter fp, old_fp;
1da177e4 LT	499	unsigned int fsize = sizeof(struct sock_filter) * fprog->len;
	500	int err;
	501
	502	/* Make sure new filter is there and in the right amounts. */
e35bedf3 KK	503	if (fprog->filter == NULL)
e35bedf3 KK	504	return -EINVAL;
1da177e4 LT	505
	506	fp = sock_kmalloc(sk, fsize+sizeof(*fp), GFP_KERNEL);
	507	if (!fp)
	508	return -ENOMEM;
	509	if (copy_from_user(fp->insns, fprog->filter, fsize)) {
4ec93edb	510	sock_kfree_s(sk, fp, fsize+sizeof(*fp));
1da177e4 LT	511	return -EFAULT;
	512	}
	513
	514	atomic_set(&fp->refcnt, 1);
	515	fp->len = fprog->len;
	516
	517	err = sk_chk_filter(fp->insns, fp->len);
d3904b73 PE	518	if (err) {
	519	sk_filter_uncharge(sk, fp);
	520	return err;
1da177e4 LT	521	}
1da177e4 LT	522
d3904b73	523	rcu_read_lock_bh();
a898def2	524	old_fp = rcu_dereference_bh(sk->sk_filter);
d3904b73 PE	525	rcu_assign_pointer(sk->sk_filter, fp);
	526	rcu_read_unlock_bh();
	527
9b013e05 OJ	528	if (old_fp)
9b013e05 OJ	529	sk_filter_delayed_uncharge(sk, old_fp);
d3904b73	530	return 0;
1da177e4	531	}
5ff3f073	532	EXPORT_SYMBOL_GPL(sk_attach_filter);
1da177e4	533
55b33325 PE	534	int sk_detach_filter(struct sock *sk)
	535	{
	536	int ret = -ENOENT;
	537	struct sk_filter *filter;
	538
	539	rcu_read_lock_bh();
a898def2	540	filter = rcu_dereference_bh(sk->sk_filter);
55b33325 PE	541	if (filter) {
55b33325 PE	542	rcu_assign_pointer(sk->sk_filter, NULL);
47e958ea	543	sk_filter_delayed_uncharge(sk, filter);
55b33325 PE	544	ret = 0;
	545	}
	546	rcu_read_unlock_bh();
	547	return ret;
	548	}
5ff3f073	549	EXPORT_SYMBOL_GPL(sk_detach_filter);