[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.
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/sched.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 <linux/skbuff.h>
#include <net/sock.h>
#include <linux/errno.h>
#include <linux/timer.h>
#include <asm/system.h>
#include <asm/uaccess.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->nh.raw + k - SKF_NET_OFF;
	else if (k >= SKF_LL_OFF)
		ptr = skb->mac.raw + k - SKF_LL_OFF;

	if (ptr >= skb->head && ptr < skb->tail)
		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_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.
 */
 
int sk_run_filter(struct sk_buff *skb, struct sock_filter *filter, int flen)
{
	/* len is UNSIGNED. Byte wide insns relies only on implicit
	   type casts to prevent reading arbitrary memory locations.
	 */
	unsigned int len = skb->len-skb->data_len;
	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:
			if (fentry->k == 0)
				return 0;
			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(*(u32 *)ptr);
				continue;
			}
			return 0;
		case BPF_LD|BPF_H|BPF_ABS:
			k = fentry->k;
 load_h:
			ptr = load_pointer(skb, k, 2, &tmp);
			if (ptr != NULL) {
				A = ntohs(*(u16 *)ptr);
				continue;
			}
			return 0;
		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;
			}
			return 0;
		case BPF_LD|BPF_W|BPF_LEN:
			A = len;
			continue;
		case BPF_LDX|BPF_W|BPF_LEN:
			X = 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 ((unsigned int)fentry->k);
		case BPF_RET|BPF_A:
			return ((unsigned int)A);
		case BPF_ST:
			mem[fentry->k] = A;
			continue;
		case BPF_STX:
			mem[fentry->k] = X;
			continue;
		default:
			/* Invalid instruction counts as RET */
			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 = htons(skb->protocol);
			continue;
		case SKF_AD_PKTTYPE:
			A = skb->pkt_type;
			continue;
		case SKF_AD_IFINDEX:
			A = skb->dev->ifindex;
			continue;
		default:
			return 0;
		}
	}

	return 0;
}

/**
 *	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 no backward jumps. It must end with a RET instruction
 *
 * Returns 0 if the rule set is legal or a negative errno code if not.
 */
int sk_chk_filter(struct sock_filter *filter, int flen)
{
	struct sock_filter *ftest;
	int pc;

	if (((unsigned int)flen >= (~0U / sizeof(struct sock_filter))) || flen == 0)
		return -EINVAL;

	/* check the filter code now */
	for (pc = 0; pc < flen; pc++) {
		/* all jumps are forward as they are not signed */
		ftest = &filter[pc];
		if (BPF_CLASS(ftest->code) == BPF_JMP) {
			/* but they mustn't jump off the end */
			if (BPF_OP(ftest->code) == 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;
			} else {
				/* for conditionals both must be safe */
 				if (pc + ftest->jt +1 >= flen ||
				    pc + ftest->jf +1 >= flen)
					return -EINVAL;
			}
		}

		/* check that memory operations use valid addresses. */
		if (ftest->k >= BPF_MEMWORDS) {
			/* but it might not be a memory operation... */
			switch (ftest->code) {
			case BPF_ST:	
			case BPF_STX:	
			case BPF_LD|BPF_MEM:	
			case BPF_LDX|BPF_MEM:	
				return -EINVAL;
			}
		}
	}

	/*
	 * The program must end with a return. We don't care where they
	 * jumped within the script (its always forwards) but in the end
	 * they _will_ hit this.
	 */
        return (BPF_CLASS(filter[flen - 1].code) == BPF_RET) ? 0 : -EINVAL;
}

/**
 *	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; 
	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 || fprog->len > BPF_MAXINSNS)
                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) {
		struct sk_filter *old_fp;

		spin_lock_bh(&sk->sk_lock.slock);
		old_fp = sk->sk_filter;
		sk->sk_filter = fp;
		spin_unlock_bh(&sk->sk_lock.slock);
		fp = old_fp;
	}

	if (fp)
		sk_filter_release(sk, fp);
	return err;
}

EXPORT_SYMBOL(sk_chk_filter);
EXPORT_SYMBOL(sk_run_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.
	16	*/
	17
	18	#include <linux/module.h>
	19	#include <linux/types.h>
	20	#include <linux/sched.h>
	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>
	30	#include <linux/skbuff.h>
	31	#include <net/sock.h>
	32	#include <linux/errno.h>
	33	#include <linux/timer.h>
	34	#include <asm/system.h>
	35	#include <asm/uaccess.h>
	36	#include <linux/filter.h>
	37
	38	/* No hurry in this branch */
0b05b2a4	39	static void __load_pointer(struct sk_buff skb, int k)
1da177e4 LT	40	{
	41	u8 *ptr = NULL;
	42
	43	if (k >= SKF_NET_OFF)
	44	ptr = skb->nh.raw + k - SKF_NET_OFF;
	45	else if (k >= SKF_LL_OFF)
	46	ptr = skb->mac.raw + k - SKF_LL_OFF;
	47
	48	if (ptr >= skb->head && ptr < skb->tail)
	49	return ptr;
	50	return NULL;
	51	}
	52
0b05b2a4 PM	53	static inline void load_pointer(struct sk_buff skb, int k,
	54	unsigned int size, void *buffer)
	55	{
	56	if (k >= 0)
	57	return skb_header_pointer(skb, k, size, buffer);
	58	else {
	59	if (k >= SKF_AD_OFF)
	60	return NULL;
	61	return __load_pointer(skb, k);
	62	}
	63	}
	64
1da177e4 LT	65	/**
	66	* sk_run_filter - run a filter on a socket
	67	* @skb: buffer to run the filter on
	68	* @filter: filter to apply
	69	* @flen: length of filter
	70	*
	71	* Decode and apply filter instructions to the skb->data.
	72	* Return length to keep, 0 for none. skb is the data we are
	73	* filtering, filter is the array of filter instructions, and
	74	* len is the number of filter blocks in the array.
	75	*/
	76
	77	int sk_run_filter(struct sk_buff skb, struct sock_filter filter, int flen)
	78	{
1da177e4 LT	79	/* len is UNSIGNED. Byte wide insns relies only on implicit
	80	type casts to prevent reading arbitrary memory locations.
	81	*/
	82	unsigned int len = skb->len-skb->data_len;
	83	struct sock_filter fentry; / We walk down these */
0b05b2a4	84	void *ptr;
1da177e4 LT	85	u32 A = 0; /* Accumulator */
	86	u32 X = 0; /* Index Register */
	87	u32 mem[BPF_MEMWORDS]; /* Scratch Memory Store */
0b05b2a4	88	u32 tmp;
1da177e4 LT	89	int k;
	90	int pc;
	91
	92	/*
	93	* Process array of filter instructions.
	94	*/
	95	for (pc = 0; pc < flen; pc++) {
	96	fentry = &filter[pc];
	97
	98	switch (fentry->code) {
	99	case BPF_ALU\|BPF_ADD\|BPF_X:
	100	A += X;
	101	continue;
	102	case BPF_ALU\|BPF_ADD\|BPF_K:
	103	A += fentry->k;
	104	continue;
	105	case BPF_ALU\|BPF_SUB\|BPF_X:
	106	A -= X;
	107	continue;
	108	case BPF_ALU\|BPF_SUB\|BPF_K:
	109	A -= fentry->k;
	110	continue;
	111	case BPF_ALU\|BPF_MUL\|BPF_X:
	112	A *= X;
	113	continue;
	114	case BPF_ALU\|BPF_MUL\|BPF_K:
	115	A *= fentry->k;
	116	continue;
	117	case BPF_ALU\|BPF_DIV\|BPF_X:
	118	if (X == 0)
	119	return 0;
	120	A /= X;
	121	continue;
	122	case BPF_ALU\|BPF_DIV\|BPF_K:
	123	if (fentry->k == 0)
	124	return 0;
	125	A /= fentry->k;
	126	continue;
	127	case BPF_ALU\|BPF_AND\|BPF_X:
	128	A &= X;
	129	continue;
	130	case BPF_ALU\|BPF_AND\|BPF_K:
	131	A &= fentry->k;
	132	continue;
	133	case BPF_ALU\|BPF_OR\|BPF_X:
	134	A \|= X;
	135	continue;
	136	case BPF_ALU\|BPF_OR\|BPF_K:
	137	A \|= fentry->k;
	138	continue;
	139	case BPF_ALU\|BPF_LSH\|BPF_X:
	140	A <<= X;
	141	continue;
	142	case BPF_ALU\|BPF_LSH\|BPF_K:
	143	A <<= fentry->k;
	144	continue;
	145	case BPF_ALU\|BPF_RSH\|BPF_X:
	146	A >>= X;
	147	continue;
	148	case BPF_ALU\|BPF_RSH\|BPF_K:
	149	A >>= fentry->k;
	150	continue;
	151	case BPF_ALU\|BPF_NEG:
	152	A = -A;
153	continue;
154	case BPF_JMP\|BPF_JA:
155	pc += fentry->k;
156	continue;
157	case BPF_JMP\|BPF_JGT\|BPF_K:
158	pc += (A > fentry->k) ? fentry->jt : fentry->jf;
159	continue;
160	case BPF_JMP\|BPF_JGE\|BPF_K:
161	pc += (A >= fentry->k) ? fentry->jt : fentry->jf;
162	continue;
163	case BPF_JMP\|BPF_JEQ\|BPF_K:
164	pc += (A == fentry->k) ? fentry->jt : fentry->jf;
165	continue;
166	case BPF_JMP\|BPF_JSET\|BPF_K:
167	pc += (A & fentry->k) ? fentry->jt : fentry->jf;
168	continue;
169	case BPF_JMP\|BPF_JGT\|BPF_X:
170	pc += (A > X) ? fentry->jt : fentry->jf;
171	continue;
172	case BPF_JMP\|BPF_JGE\|BPF_X:
173	pc += (A >= X) ? fentry->jt : fentry->jf;
174	continue;
175	case BPF_JMP\|BPF_JEQ\|BPF_X:
176	pc += (A == X) ? fentry->jt : fentry->jf;
177	continue;
178	case BPF_JMP\|BPF_JSET\|BPF_X:
179	pc += (A & X) ? fentry->jt : fentry->jf;
180	continue;
181	case BPF_LD\|BPF_W\|BPF_ABS:
182	k = fentry->k;
183	load_w:
0b05b2a4 PM	184	ptr = load_pointer(skb, k, 4, &tmp);
	185	if (ptr != NULL) {
	186	A = ntohl((u32 )ptr);
	187	continue;
1da177e4 LT	188	}
	189	return 0;
	190	case BPF_LD\|BPF_H\|BPF_ABS:
	191	k = fentry->k;
	192	load_h:
0b05b2a4 PM	193	ptr = load_pointer(skb, k, 2, &tmp);
	194	if (ptr != NULL) {
	195	A = ntohs((u16 )ptr);
	196	continue;
1da177e4 LT	197	}
	198	return 0;
	199	case BPF_LD\|BPF_B\|BPF_ABS:
	200	k = fentry->k;
	201	load_b:
0b05b2a4 PM	202	ptr = load_pointer(skb, k, 1, &tmp);
	203	if (ptr != NULL) {
	204	A = (u8 )ptr;
	205	continue;
1da177e4 LT	206	}
	207	return 0;
	208	case BPF_LD\|BPF_W\|BPF_LEN:
	209	A = len;
	210	continue;
	211	case BPF_LDX\|BPF_W\|BPF_LEN:
	212	X = len;
	213	continue;
	214	case BPF_LD\|BPF_W\|BPF_IND:
	215	k = X + fentry->k;
	216	goto load_w;
	217	case BPF_LD\|BPF_H\|BPF_IND:
	218	k = X + fentry->k;
	219	goto load_h;
	220	case BPF_LD\|BPF_B\|BPF_IND:
	221	k = X + fentry->k;
	222	goto load_b;
	223	case BPF_LDX\|BPF_B\|BPF_MSH:
0b05b2a4 PM	224	ptr = load_pointer(skb, fentry->k, 1, &tmp);
	225	if (ptr != NULL) {
	226	X = ((u8 )ptr & 0xf) << 2;
	227	continue;
	228	}
	229	return 0;
1da177e4 LT	230	case BPF_LD\|BPF_IMM:
	231	A = fentry->k;
	232	continue;
	233	case BPF_LDX\|BPF_IMM:
	234	X = fentry->k;
	235	continue;
	236	case BPF_LD\|BPF_MEM:
	237	A = mem[fentry->k];
	238	continue;
	239	case BPF_LDX\|BPF_MEM:
	240	X = mem[fentry->k];
	241	continue;
	242	case BPF_MISC\|BPF_TAX:
	243	X = A;
	244	continue;
	245	case BPF_MISC\|BPF_TXA:
	246	A = X;
	247	continue;
	248	case BPF_RET\|BPF_K:
	249	return ((unsigned int)fentry->k);
	250	case BPF_RET\|BPF_A:
	251	return ((unsigned int)A);
	252	case BPF_ST:
	253	mem[fentry->k] = A;
	254	continue;
	255	case BPF_STX:
	256	mem[fentry->k] = X;
	257	continue;
	258	default:
	259	/* Invalid instruction counts as RET */
	260	return 0;
	261	}
	262
	263	/*
	264	* Handle ancillary data, which are impossible
	265	* (or very difficult) to get parsing packet contents.
	266	*/
	267	switch (k-SKF_AD_OFF) {
	268	case SKF_AD_PROTOCOL:
	269	A = htons(skb->protocol);
	270	continue;
	271	case SKF_AD_PKTTYPE:
	272	A = skb->pkt_type;
	273	continue;
	274	case SKF_AD_IFINDEX:
	275	A = skb->dev->ifindex;
	276	continue;
	277	default:
	278	return 0;
	279	}
	280	}
	281
	282	return 0;
	283	}
	284
	285	/**
	286	* sk_chk_filter - verify socket filter code
	287	* @filter: filter to verify
	288	* @flen: length of filter
	289	*
	290	* Check the user's filter code. If we let some ugly
	291	* filter code slip through kaboom! The filter must contain
	292	* no references or jumps that are out of range, no illegal instructions
	293	* and no backward jumps. It must end with a RET instruction
294	*
295	* Returns 0 if the rule set is legal or a negative errno code if not.
296	*/
297	int sk_chk_filter(struct sock_filter *filter, int flen)
298	{
299	struct sock_filter *ftest;
300	int pc;
301
302	if (((unsigned int)flen >= (~0U / sizeof(struct sock_filter))) \|\| flen == 0)
303	return -EINVAL;
304
305	/* check the filter code now */
306	for (pc = 0; pc < flen; pc++) {
307	/* all jumps are forward as they are not signed */
308	ftest = &filter[pc];
309	if (BPF_CLASS(ftest->code) == BPF_JMP) {
310	/* but they mustn't jump off the end */
311	if (BPF_OP(ftest->code) == BPF_JA) {
312	/*
313	* Note, the large ftest->k might cause loops.
314	* Compare this with conditional jumps below,
315	* where offsets are limited. --ANK (981016)
316	*/
317	if (ftest->k >= (unsigned)(flen-pc-1))
318	return -EINVAL;
319	} else {
320	/* for conditionals both must be safe */
321	if (pc + ftest->jt +1 >= flen \|\|
322	pc + ftest->jf +1 >= flen)
323	return -EINVAL;
324	}
325	}
326
327	/* check that memory operations use valid addresses. */
328	if (ftest->k >= BPF_MEMWORDS) {
329	/* but it might not be a memory operation... */
330	switch (ftest->code) {
331	case BPF_ST:
332	case BPF_STX:
333	case BPF_LD\|BPF_MEM:
334	case BPF_LDX\|BPF_MEM:
335	return -EINVAL;
336	}
337	}
338	}
339
340	/*
341	* The program must end with a return. We don't care where they
342	* jumped within the script (its always forwards) but in the end
343	* they _will_ hit this.
344	*/
345	return (BPF_CLASS(filter[flen - 1].code) == BPF_RET) ? 0 : -EINVAL;
346	}
347
348	/**
349	* sk_attach_filter - attach a socket filter
350	* @fprog: the filter program
351	* @sk: the socket to use
352	*
353	* Attach the user's filter code. We first run some sanity checks on
354	* it to make sure it does not explode on us later. If an error
355	* occurs or there is insufficient memory for the filter a negative
356	* errno code is returned. On success the return is zero.
357	*/
358	int sk_attach_filter(struct sock_fprog fprog, struct sock sk)
359	{
360	struct sk_filter *fp;
361	unsigned int fsize = sizeof(struct sock_filter) * fprog->len;
362	int err;
363
364	/* Make sure new filter is there and in the right amounts. */
365	if (fprog->filter == NULL \|\| fprog->len > BPF_MAXINSNS)
366	return -EINVAL;
367
368	fp = sock_kmalloc(sk, fsize+sizeof(*fp), GFP_KERNEL);
369	if (!fp)
370	return -ENOMEM;
371	if (copy_from_user(fp->insns, fprog->filter, fsize)) {
372	sock_kfree_s(sk, fp, fsize+sizeof(*fp));
373	return -EFAULT;
374	}
375
376	atomic_set(&fp->refcnt, 1);
377	fp->len = fprog->len;
378
379	err = sk_chk_filter(fp->insns, fp->len);
380	if (!err) {
381	struct sk_filter *old_fp;
382
383	spin_lock_bh(&sk->sk_lock.slock);
384	old_fp = sk->sk_filter;
385	sk->sk_filter = fp;
386	spin_unlock_bh(&sk->sk_lock.slock);
387	fp = old_fp;
388	}
389
390	if (fp)
391	sk_filter_release(sk, fp);
392	return err;
393	}
394
395	EXPORT_SYMBOL(sk_chk_filter);
396	EXPORT_SYMBOL(sk_run_filter);