[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
 *	@needlock: set to 1 if the sock is not locked by caller.
 *
 * 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(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 = ntohl(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 = ntohs(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_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;
		}
		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(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;
}

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

	rcu_read_lock_bh();
	filter = rcu_dereference(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;
}
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
	71	* @needlock: set to 1 if the sock is not locked by caller.
	72	*
	73	* Run the filter code and then cut skb->data to correct size returned by
	74	* sk_run_filter. If pkt_len is 0 we toss packet. If skb->len is smaller
	75	* than pkt_len we keep whole skb->data. This is the socket level
	76	* wrapper to sk_run_filter. It returns 0 if the packet should
	77	* be accepted or -EPERM if the packet should be tossed.
	78	*
	79	*/
	80	int sk_filter(struct sock sk, struct sk_buff skb)
	81	{
	82	int err;
	83	struct sk_filter *filter;
	84
	85	err = security_sock_rcv_skb(sk, skb);
	86	if (err)
	87	return err;
	88
	89	rcu_read_lock_bh();
	90	filter = rcu_dereference(sk->sk_filter);
	91	if (filter) {
	92	unsigned int pkt_len = sk_run_filter(skb, filter->insns,
	93	filter->len);
	94	err = pkt_len ? pskb_trim(skb, pkt_len) : -EPERM;
	95	}
	96	rcu_read_unlock_bh();
	97
	98	return err;
	99	}
	100	EXPORT_SYMBOL(sk_filter);
	101
1da177e4	102	/**
2966b66c	103	* sk_run_filter - run a filter on a socket
1da177e4 LT	104	* @skb: buffer to run the filter on
	105	* @filter: filter to apply
	106	* @flen: length of filter
	107	*
	108	* Decode and apply filter instructions to the skb->data.
	109	* Return length to keep, 0 for none. skb is the data we are
	110	* filtering, filter is the array of filter instructions, and
	111	* len is the number of filter blocks in the array.
	112	*/
4bad4dc9	113	unsigned int sk_run_filter(struct sk_buff skb, struct sock_filter filter, int flen)
1da177e4	114	{
1da177e4	115	struct sock_filter fentry; / We walk down these */
0b05b2a4	116	void *ptr;
2966b66c KK	117	u32 A = 0; /* Accumulator */
2966b66c KK	118	u32 X = 0; /* Index Register */
1da177e4	119	u32 mem[BPF_MEMWORDS]; /* Scratch Memory Store */
0b05b2a4	120	u32 tmp;
1da177e4 LT	121	int k;
	122	int pc;
	123
	124	/*
	125	* Process array of filter instructions.
	126	*/
	127	for (pc = 0; pc < flen; pc++) {
	128	fentry = &filter[pc];
4ec93edb	129
1da177e4 LT	130	switch (fentry->code) {
	131	case BPF_ALU\|BPF_ADD\|BPF_X:
	132	A += X;
	133	continue;
	134	case BPF_ALU\|BPF_ADD\|BPF_K:
	135	A += fentry->k;
	136	continue;
	137	case BPF_ALU\|BPF_SUB\|BPF_X:
	138	A -= X;
	139	continue;
	140	case BPF_ALU\|BPF_SUB\|BPF_K:
	141	A -= fentry->k;
	142	continue;
	143	case BPF_ALU\|BPF_MUL\|BPF_X:
	144	A *= X;
	145	continue;
	146	case BPF_ALU\|BPF_MUL\|BPF_K:
	147	A *= fentry->k;
	148	continue;
	149	case BPF_ALU\|BPF_DIV\|BPF_X:
	150	if (X == 0)
	151	return 0;
	152	A /= X;
	153	continue;
	154	case BPF_ALU\|BPF_DIV\|BPF_K:
1da177e4 LT	155	A /= fentry->k;
	156	continue;
	157	case BPF_ALU\|BPF_AND\|BPF_X:
	158	A &= X;
	159	continue;
	160	case BPF_ALU\|BPF_AND\|BPF_K:
	161	A &= fentry->k;
	162	continue;
	163	case BPF_ALU\|BPF_OR\|BPF_X:
	164	A \|= X;
	165	continue;
	166	case BPF_ALU\|BPF_OR\|BPF_K:
	167	A \|= fentry->k;
	168	continue;
	169	case BPF_ALU\|BPF_LSH\|BPF_X:
	170	A <<= X;
	171	continue;
	172	case BPF_ALU\|BPF_LSH\|BPF_K:
	173	A <<= fentry->k;
	174	continue;
	175	case BPF_ALU\|BPF_RSH\|BPF_X:
	176	A >>= X;
	177	continue;
	178	case BPF_ALU\|BPF_RSH\|BPF_K:
	179	A >>= fentry->k;
	180	continue;
	181	case BPF_ALU\|BPF_NEG:
	182	A = -A;
	183	continue;
	184	case BPF_JMP\|BPF_JA:
	185	pc += fentry->k;
	186	continue;
	187	case BPF_JMP\|BPF_JGT\|BPF_K:
	188	pc += (A > fentry->k) ? fentry->jt : fentry->jf;
	189	continue;
	190	case BPF_JMP\|BPF_JGE\|BPF_K:
	191	pc += (A >= fentry->k) ? fentry->jt : fentry->jf;
	192	continue;
	193	case BPF_JMP\|BPF_JEQ\|BPF_K:
	194	pc += (A == fentry->k) ? fentry->jt : fentry->jf;
	195	continue;
	196	case BPF_JMP\|BPF_JSET\|BPF_K:
	197	pc += (A & fentry->k) ? fentry->jt : fentry->jf;
	198	continue;
	199	case BPF_JMP\|BPF_JGT\|BPF_X:
	200	pc += (A > X) ? fentry->jt : fentry->jf;
	201	continue;
	202	case BPF_JMP\|BPF_JGE\|BPF_X:
	203	pc += (A >= X) ? fentry->jt : fentry->jf;
	204	continue;
	205	case BPF_JMP\|BPF_JEQ\|BPF_X:
	206	pc += (A == X) ? fentry->jt : fentry->jf;
	207	continue;
	208	case BPF_JMP\|BPF_JSET\|BPF_X:
	209	pc += (A & X) ? fentry->jt : fentry->jf;
	210	continue;
	211	case BPF_LD\|BPF_W\|BPF_ABS:
	212	k = fentry->k;
e35bedf3	213	load_w:
0b05b2a4 PM	214	ptr = load_pointer(skb, k, 4, &tmp);
0b05b2a4 PM	215	if (ptr != NULL) {
252e3346	216	A = ntohl(get_unaligned((__be32 *)ptr));
0b05b2a4	217	continue;
1da177e4	218	}
1198ad00	219	break;
1da177e4 LT	220	case BPF_LD\|BPF_H\|BPF_ABS:
1da177e4 LT	221	k = fentry->k;
e35bedf3	222	load_h:
0b05b2a4 PM	223	ptr = load_pointer(skb, k, 2, &tmp);
0b05b2a4 PM	224	if (ptr != NULL) {
252e3346	225	A = ntohs(get_unaligned((__be16 *)ptr));
0b05b2a4	226	continue;
1da177e4	227	}
1198ad00	228	break;
1da177e4 LT	229	case BPF_LD\|BPF_B\|BPF_ABS:
	230	k = fentry->k;
	231	load_b:
0b05b2a4 PM	232	ptr = load_pointer(skb, k, 1, &tmp);
	233	if (ptr != NULL) {
	234	A = (u8 )ptr;
	235	continue;
1da177e4	236	}
1198ad00	237	break;
1da177e4	238	case BPF_LD\|BPF_W\|BPF_LEN:
3154e540	239	A = skb->len;
1da177e4 LT	240	continue;
1da177e4 LT	241	case BPF_LDX\|BPF_W\|BPF_LEN:
3154e540	242	X = skb->len;
1da177e4 LT	243	continue;
	244	case BPF_LD\|BPF_W\|BPF_IND:
	245	k = X + fentry->k;
	246	goto load_w;
	247	case BPF_LD\|BPF_H\|BPF_IND:
	248	k = X + fentry->k;
	249	goto load_h;
	250	case BPF_LD\|BPF_B\|BPF_IND:
	251	k = X + fentry->k;
	252	goto load_b;
	253	case BPF_LDX\|BPF_B\|BPF_MSH:
0b05b2a4 PM	254	ptr = load_pointer(skb, fentry->k, 1, &tmp);
	255	if (ptr != NULL) {
	256	X = ((u8 )ptr & 0xf) << 2;
	257	continue;
	258	}
	259	return 0;
1da177e4 LT	260	case BPF_LD\|BPF_IMM:
	261	A = fentry->k;
	262	continue;
	263	case BPF_LDX\|BPF_IMM:
	264	X = fentry->k;
	265	continue;
	266	case BPF_LD\|BPF_MEM:
	267	A = mem[fentry->k];
	268	continue;
	269	case BPF_LDX\|BPF_MEM:
	270	X = mem[fentry->k];
	271	continue;
	272	case BPF_MISC\|BPF_TAX:
	273	X = A;
	274	continue;
	275	case BPF_MISC\|BPF_TXA:
	276	A = X;
	277	continue;
	278	case BPF_RET\|BPF_K:
4bad4dc9	279	return fentry->k;
1da177e4	280	case BPF_RET\|BPF_A:
4bad4dc9	281	return A;
1da177e4 LT	282	case BPF_ST:
	283	mem[fentry->k] = A;
	284	continue;
	285	case BPF_STX:
	286	mem[fentry->k] = X;
	287	continue;
	288	default:
93699863	289	WARN_ON(1);
1da177e4 LT	290	return 0;
	291	}
	292
	293	/*
	294	* Handle ancillary data, which are impossible
	295	* (or very difficult) to get parsing packet contents.
	296	*/
	297	switch (k-SKF_AD_OFF) {
	298	case SKF_AD_PROTOCOL:
252e3346	299	A = ntohs(skb->protocol);
1da177e4 LT	300	continue;
	301	case SKF_AD_PKTTYPE:
	302	A = skb->pkt_type;
	303	continue;
	304	case SKF_AD_IFINDEX:
	305	A = skb->dev->ifindex;
	306	continue;
4738c1db PM	307	case SKF_AD_NLATTR: {
	308	struct nlattr *nla;
	309
	310	if (skb_is_nonlinear(skb))
	311	return 0;
	312	if (A > skb->len - sizeof(struct nlattr))
	313	return 0;
	314
	315	nla = nla_find((struct nlattr *)&skb->data[A],
	316	skb->len - A, X);
	317	if (nla)
	318	A = (void )nla - (void )skb->data;
	319	else
	320	A = 0;
	321	continue;
	322	}
1da177e4 LT	323	default:
	324	return 0;
	325	}
	326	}
	327
	328	return 0;
	329	}
b715631f	330	EXPORT_SYMBOL(sk_run_filter);
1da177e4 LT	331
	332	/**
	333	* sk_chk_filter - verify socket filter code
	334	* @filter: filter to verify
	335	* @flen: length of filter
	336	*
	337	* Check the user's filter code. If we let some ugly
	338	* filter code slip through kaboom! The filter must contain
93699863 KK	339	* no references or jumps that are out of range, no illegal
93699863 KK	340	* instructions, and must end with a RET instruction.
1da177e4	341	*
7b11f69f KK	342	* All jumps are forward as they are not signed.
	343	*
	344	* Returns 0 if the rule set is legal or -EINVAL if not.
1da177e4 LT	345	*/
	346	int sk_chk_filter(struct sock_filter *filter, int flen)
	347	{
	348	struct sock_filter *ftest;
	349	int pc;
	350
1b93ae64	351	if (flen == 0 \|\| flen > BPF_MAXINSNS)
1da177e4 LT	352	return -EINVAL;
	353
	354	/* check the filter code now */
	355	for (pc = 0; pc < flen; pc++) {
1da177e4	356	ftest = &filter[pc];
1da177e4	357
93699863 KK	358	/* Only allow valid instructions */
	359	switch (ftest->code) {
	360	case BPF_ALU\|BPF_ADD\|BPF_K:
	361	case BPF_ALU\|BPF_ADD\|BPF_X:
	362	case BPF_ALU\|BPF_SUB\|BPF_K:
	363	case BPF_ALU\|BPF_SUB\|BPF_X:
	364	case BPF_ALU\|BPF_MUL\|BPF_K:
	365	case BPF_ALU\|BPF_MUL\|BPF_X:
	366	case BPF_ALU\|BPF_DIV\|BPF_X:
	367	case BPF_ALU\|BPF_AND\|BPF_K:
	368	case BPF_ALU\|BPF_AND\|BPF_X:
	369	case BPF_ALU\|BPF_OR\|BPF_K:
	370	case BPF_ALU\|BPF_OR\|BPF_X:
	371	case BPF_ALU\|BPF_LSH\|BPF_K:
	372	case BPF_ALU\|BPF_LSH\|BPF_X:
	373	case BPF_ALU\|BPF_RSH\|BPF_K:
	374	case BPF_ALU\|BPF_RSH\|BPF_X:
	375	case BPF_ALU\|BPF_NEG:
	376	case BPF_LD\|BPF_W\|BPF_ABS:
	377	case BPF_LD\|BPF_H\|BPF_ABS:
	378	case BPF_LD\|BPF_B\|BPF_ABS:
	379	case BPF_LD\|BPF_W\|BPF_LEN:
	380	case BPF_LD\|BPF_W\|BPF_IND:
	381	case BPF_LD\|BPF_H\|BPF_IND:
	382	case BPF_LD\|BPF_B\|BPF_IND:
	383	case BPF_LD\|BPF_IMM:
	384	case BPF_LDX\|BPF_W\|BPF_LEN:
	385	case BPF_LDX\|BPF_B\|BPF_MSH:
	386	case BPF_LDX\|BPF_IMM:
	387	case BPF_MISC\|BPF_TAX:
	388	case BPF_MISC\|BPF_TXA:
	389	case BPF_RET\|BPF_K:
	390	case BPF_RET\|BPF_A:
	391	break;
	392
	393	/* Some instructions need special checks */
fb0d366b	394
93699863 KK	395	case BPF_ALU\|BPF_DIV\|BPF_K:
	396	/* check for division by zero */
	397	if (ftest->k == 0)
1da177e4	398	return -EINVAL;
93699863 KK	399	break;
	400
	401	case BPF_LD\|BPF_MEM:
	402	case BPF_LDX\|BPF_MEM:
	403	case BPF_ST:
	404	case BPF_STX:
	405	/* check for invalid memory addresses */
	406	if (ftest->k >= BPF_MEMWORDS)
	407	return -EINVAL;
	408	break;
	409
	410	case BPF_JMP\|BPF_JA:
	411	/*
	412	* Note, the large ftest->k might cause loops.
	413	* Compare this with conditional jumps below,
	414	* where offsets are limited. --ANK (981016)
	415	*/
	416	if (ftest->k >= (unsigned)(flen-pc-1))
	417	return -EINVAL;
	418	break;
	419
	420	case BPF_JMP\|BPF_JEQ\|BPF_K:
	421	case BPF_JMP\|BPF_JEQ\|BPF_X:
	422	case BPF_JMP\|BPF_JGE\|BPF_K:
	423	case BPF_JMP\|BPF_JGE\|BPF_X:
	424	case BPF_JMP\|BPF_JGT\|BPF_K:
	425	case BPF_JMP\|BPF_JGT\|BPF_X:
	426	case BPF_JMP\|BPF_JSET\|BPF_K:
	427	case BPF_JMP\|BPF_JSET\|BPF_X:
	428	/* for conditionals both must be safe */
e35bedf3	429	if (pc + ftest->jt + 1 >= flen \|\|
93699863 KK	430	pc + ftest->jf + 1 >= flen)
	431	return -EINVAL;
	432	break;
	433
	434	default:
	435	return -EINVAL;
1da177e4 LT	436	}
	437	}
	438
e35bedf3	439	return (BPF_CLASS(filter[flen - 1].code) == BPF_RET) ? 0 : -EINVAL;
1da177e4	440	}
b715631f	441	EXPORT_SYMBOL(sk_chk_filter);
1da177e4	442
47e958ea PE	443	/**
	444	* sk_filter_rcu_release: Release a socket filter by rcu_head
	445	* @rcu: rcu_head that contains the sk_filter to free
	446	*/
	447	static void sk_filter_rcu_release(struct rcu_head *rcu)
	448	{
	449	struct sk_filter *fp = container_of(rcu, struct sk_filter, rcu);
	450
	451	sk_filter_release(fp);
	452	}
	453
	454	static void sk_filter_delayed_uncharge(struct sock sk, struct sk_filter fp)
	455	{
	456	unsigned int size = sk_filter_len(fp);
	457
	458	atomic_sub(size, &sk->sk_omem_alloc);
	459	call_rcu_bh(&fp->rcu, sk_filter_rcu_release);
	460	}
	461
1da177e4 LT	462	/**
	463	* sk_attach_filter - attach a socket filter
	464	* @fprog: the filter program
	465	* @sk: the socket to use
	466	*
	467	* Attach the user's filter code. We first run some sanity checks on
	468	* it to make sure it does not explode on us later. If an error
	469	* occurs or there is insufficient memory for the filter a negative
	470	* errno code is returned. On success the return is zero.
	471	*/
	472	int sk_attach_filter(struct sock_fprog fprog, struct sock sk)
	473	{
d3904b73	474	struct sk_filter fp, old_fp;
1da177e4 LT	475	unsigned int fsize = sizeof(struct sock_filter) * fprog->len;
	476	int err;
	477
	478	/* Make sure new filter is there and in the right amounts. */
e35bedf3 KK	479	if (fprog->filter == NULL)
e35bedf3 KK	480	return -EINVAL;
1da177e4 LT	481
	482	fp = sock_kmalloc(sk, fsize+sizeof(*fp), GFP_KERNEL);
	483	if (!fp)
	484	return -ENOMEM;
	485	if (copy_from_user(fp->insns, fprog->filter, fsize)) {
4ec93edb	486	sock_kfree_s(sk, fp, fsize+sizeof(*fp));
1da177e4 LT	487	return -EFAULT;
	488	}
	489
	490	atomic_set(&fp->refcnt, 1);
	491	fp->len = fprog->len;
	492
	493	err = sk_chk_filter(fp->insns, fp->len);
d3904b73 PE	494	if (err) {
	495	sk_filter_uncharge(sk, fp);
	496	return err;
1da177e4 LT	497	}
1da177e4 LT	498
d3904b73 PE	499	rcu_read_lock_bh();
	500	old_fp = rcu_dereference(sk->sk_filter);
	501	rcu_assign_pointer(sk->sk_filter, fp);
	502	rcu_read_unlock_bh();
	503
9b013e05 OJ	504	if (old_fp)
9b013e05 OJ	505	sk_filter_delayed_uncharge(sk, old_fp);
d3904b73	506	return 0;
1da177e4 LT	507	}
1da177e4 LT	508
55b33325 PE	509	int sk_detach_filter(struct sock *sk)
	510	{
	511	int ret = -ENOENT;
	512	struct sk_filter *filter;
	513
	514	rcu_read_lock_bh();
	515	filter = rcu_dereference(sk->sk_filter);
	516	if (filter) {
	517	rcu_assign_pointer(sk->sk_filter, NULL);
47e958ea	518	sk_filter_delayed_uncharge(sk, filter);
55b33325 PE	519	ret = 0;
	520	}
	521	rcu_read_unlock_bh();
	522	return ret;
	523	}