[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 u8 *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;
}

/**
 *	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)
{
	unsigned char *data = skb->data;
	/* 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 */
	u32 A = 0;	   		/* Accumulator */
	u32 X = 0;   			/* Index Register */
	u32 mem[BPF_MEMWORDS];		/* Scratch Memory Store */
	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:
			if (k >= 0 && (unsigned int)(k+sizeof(u32)) <= len) {
				A = ntohl(*(u32*)&data[k]);
				continue;
			}
			if (k < 0) {
				u8 *ptr;

				if (k >= SKF_AD_OFF)
					break;
				ptr = load_pointer(skb, k);
				if (ptr) {
					A = ntohl(*(u32*)ptr);
					continue;
				}
			} else {
				u32 _tmp, *p;
				p = skb_header_pointer(skb, k, 4, &_tmp);
				if (p != NULL) {
					A = ntohl(*p);
					continue;
				}
			}
			return 0;
		case BPF_LD|BPF_H|BPF_ABS:
			k = fentry->k;
 load_h:
			if (k >= 0 && (unsigned int)(k + sizeof(u16)) <= len) {
				A = ntohs(*(u16*)&data[k]);
				continue;
			}
			if (k < 0) {
				u8 *ptr;

				if (k >= SKF_AD_OFF)
					break;
				ptr = load_pointer(skb, k);
				if (ptr) {
					A = ntohs(*(u16*)ptr);
					continue;
				}
			} else {
				u16 _tmp, *p;
				p = skb_header_pointer(skb, k, 2, &_tmp);
				if (p != NULL) {
					A = ntohs(*p);
					continue;
				}
			}
			return 0;
		case BPF_LD|BPF_B|BPF_ABS:
			k = fentry->k;
load_b:
			if (k >= 0 && (unsigned int)k < len) {
				A = data[k];
				continue;
			}
			if (k < 0) {
				u8 *ptr;

				if (k >= SKF_AD_OFF)
					break;
				ptr = load_pointer(skb, k);
				if (ptr) {
					A = *ptr;
					continue;
				}
			} else {
				u8 _tmp, *p;
				p = skb_header_pointer(skb, k, 1, &_tmp);
				if (p != NULL) {
					A = *p;
					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:
			if (fentry->k >= len)
				return 0;
			X = (data[fentry->k] & 0xf) << 2;
			continue;
		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 */
	39	static u8 load_pointer(struct sk_buff skb, int k)
	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
	53	/**
	54	* sk_run_filter - run a filter on a socket
	55	* @skb: buffer to run the filter on
	56	* @filter: filter to apply
	57	* @flen: length of filter
	58	*
	59	* Decode and apply filter instructions to the skb->data.
	60	* Return length to keep, 0 for none. skb is the data we are
	61	* filtering, filter is the array of filter instructions, and
	62	* len is the number of filter blocks in the array.
	63	*/
	64
65	int sk_run_filter(struct sk_buff skb, struct sock_filter filter, int flen)
66	{
67	unsigned char *data = skb->data;
68	/* len is UNSIGNED. Byte wide insns relies only on implicit
69	type casts to prevent reading arbitrary memory locations.
70	*/
71	unsigned int len = skb->len-skb->data_len;
72	struct sock_filter fentry; / We walk down these */
73	u32 A = 0; /* Accumulator */
74	u32 X = 0; /* Index Register */
75	u32 mem[BPF_MEMWORDS]; /* Scratch Memory Store */
76	int k;
77	int pc;
78
79	/*
80	* Process array of filter instructions.
81	*/
82	for (pc = 0; pc < flen; pc++) {
83	fentry = &filter[pc];
84
85	switch (fentry->code) {
86	case BPF_ALU\|BPF_ADD\|BPF_X:
87	A += X;
88	continue;
89	case BPF_ALU\|BPF_ADD\|BPF_K:
90	A += fentry->k;
91	continue;
92	case BPF_ALU\|BPF_SUB\|BPF_X:
93	A -= X;
94	continue;
95	case BPF_ALU\|BPF_SUB\|BPF_K:
96	A -= fentry->k;
97	continue;
98	case BPF_ALU\|BPF_MUL\|BPF_X:
99	A *= X;
100	continue;
101	case BPF_ALU\|BPF_MUL\|BPF_K:
102	A *= fentry->k;
103	continue;
104	case BPF_ALU\|BPF_DIV\|BPF_X:
105	if (X == 0)
106	return 0;
107	A /= X;
108	continue;
109	case BPF_ALU\|BPF_DIV\|BPF_K:
110	if (fentry->k == 0)
111	return 0;
112	A /= fentry->k;
113	continue;
114	case BPF_ALU\|BPF_AND\|BPF_X:
115	A &= X;
116	continue;
117	case BPF_ALU\|BPF_AND\|BPF_K:
118	A &= fentry->k;
119	continue;
120	case BPF_ALU\|BPF_OR\|BPF_X:
121	A \|= X;
122	continue;
123	case BPF_ALU\|BPF_OR\|BPF_K:
124	A \|= fentry->k;
125	continue;
126	case BPF_ALU\|BPF_LSH\|BPF_X:
127	A <<= X;
128	continue;
129	case BPF_ALU\|BPF_LSH\|BPF_K:
130	A <<= fentry->k;
131	continue;
132	case BPF_ALU\|BPF_RSH\|BPF_X:
133	A >>= X;
134	continue;
135	case BPF_ALU\|BPF_RSH\|BPF_K:
136	A >>= fentry->k;
137	continue;
138	case BPF_ALU\|BPF_NEG:
139	A = -A;
140	continue;
141	case BPF_JMP\|BPF_JA:
142	pc += fentry->k;
143	continue;
144	case BPF_JMP\|BPF_JGT\|BPF_K:
145	pc += (A > fentry->k) ? fentry->jt : fentry->jf;
146	continue;
147	case BPF_JMP\|BPF_JGE\|BPF_K:
148	pc += (A >= fentry->k) ? fentry->jt : fentry->jf;
149	continue;
150	case BPF_JMP\|BPF_JEQ\|BPF_K:
151	pc += (A == fentry->k) ? fentry->jt : fentry->jf;
152	continue;
153	case BPF_JMP\|BPF_JSET\|BPF_K:
154	pc += (A & fentry->k) ? fentry->jt : fentry->jf;
155	continue;
156	case BPF_JMP\|BPF_JGT\|BPF_X:
157	pc += (A > X) ? fentry->jt : fentry->jf;
158	continue;
159	case BPF_JMP\|BPF_JGE\|BPF_X:
160	pc += (A >= X) ? fentry->jt : fentry->jf;
161	continue;
162	case BPF_JMP\|BPF_JEQ\|BPF_X:
163	pc += (A == X) ? fentry->jt : fentry->jf;
164	continue;
165	case BPF_JMP\|BPF_JSET\|BPF_X:
166	pc += (A & X) ? fentry->jt : fentry->jf;
167	continue;
168	case BPF_LD\|BPF_W\|BPF_ABS:
169	k = fentry->k;
170	load_w:
171	if (k >= 0 && (unsigned int)(k+sizeof(u32)) <= len) {
172	A = ntohl((u32)&data[k]);
173	continue;
174	}
175	if (k < 0) {
176	u8 *ptr;
177
178	if (k >= SKF_AD_OFF)
179	break;
180	ptr = load_pointer(skb, k);
181	if (ptr) {
182	A = ntohl((u32)ptr);
183	continue;
184	}
185	} else {
186	u32 _tmp, *p;
187	p = skb_header_pointer(skb, k, 4, &_tmp);
188	if (p != NULL) {
189	A = ntohl(*p);
190	continue;
191	}
192	}
193	return 0;
194	case BPF_LD\|BPF_H\|BPF_ABS:
195	k = fentry->k;
196	load_h:
197	if (k >= 0 && (unsigned int)(k + sizeof(u16)) <= len) {
198	A = ntohs((u16)&data[k]);
199	continue;
200	}
201	if (k < 0) {
202	u8 *ptr;
203
204	if (k >= SKF_AD_OFF)
205	break;
206	ptr = load_pointer(skb, k);
207	if (ptr) {
208	A = ntohs((u16)ptr);
209	continue;
210	}
211	} else {
212	u16 _tmp, *p;
213	p = skb_header_pointer(skb, k, 2, &_tmp);
214	if (p != NULL) {
215	A = ntohs(*p);
216	continue;
217	}
218	}
219	return 0;
220	case BPF_LD\|BPF_B\|BPF_ABS:
221	k = fentry->k;
222	load_b:
223	if (k >= 0 && (unsigned int)k < len) {
224	A = data[k];
225	continue;
226	}
227	if (k < 0) {
228	u8 *ptr;
229
230	if (k >= SKF_AD_OFF)
231	break;
232	ptr = load_pointer(skb, k);
233	if (ptr) {
234	A = *ptr;
235	continue;
236	}
237	} else {
238	u8 _tmp, *p;
239	p = skb_header_pointer(skb, k, 1, &_tmp);
240	if (p != NULL) {
241	A = *p;
242	continue;
243	}
244	}
245	return 0;
246	case BPF_LD\|BPF_W\|BPF_LEN:
247	A = len;
248	continue;
249	case BPF_LDX\|BPF_W\|BPF_LEN:
250	X = len;
251	continue;
252	case BPF_LD\|BPF_W\|BPF_IND:
253	k = X + fentry->k;
254	goto load_w;
255	case BPF_LD\|BPF_H\|BPF_IND:
256	k = X + fentry->k;
257	goto load_h;
258	case BPF_LD\|BPF_B\|BPF_IND:
259	k = X + fentry->k;
260	goto load_b;
261	case BPF_LDX\|BPF_B\|BPF_MSH:
262	if (fentry->k >= len)
263	return 0;
264	X = (data[fentry->k] & 0xf) << 2;
265	continue;
266	case BPF_LD\|BPF_IMM:
267	A = fentry->k;
268	continue;
269	case BPF_LDX\|BPF_IMM:
270	X = fentry->k;
271	continue;
272	case BPF_LD\|BPF_MEM:
273	A = mem[fentry->k];
274	continue;
275	case BPF_LDX\|BPF_MEM:
276	X = mem[fentry->k];
277	continue;
278	case BPF_MISC\|BPF_TAX:
279	X = A;
280	continue;
281	case BPF_MISC\|BPF_TXA:
282	A = X;
283	continue;
284	case BPF_RET\|BPF_K:
285	return ((unsigned int)fentry->k);
286	case BPF_RET\|BPF_A:
287	return ((unsigned int)A);
288	case BPF_ST:
289	mem[fentry->k] = A;
290	continue;
291	case BPF_STX:
292	mem[fentry->k] = X;
293	continue;
294	default:
295	/* Invalid instruction counts as RET */
296	return 0;
297	}
298
299	/*
300	* Handle ancillary data, which are impossible
301	* (or very difficult) to get parsing packet contents.
302	*/
303	switch (k-SKF_AD_OFF) {
304	case SKF_AD_PROTOCOL:
305	A = htons(skb->protocol);
306	continue;
307	case SKF_AD_PKTTYPE:
308	A = skb->pkt_type;
309	continue;
310	case SKF_AD_IFINDEX:
311	A = skb->dev->ifindex;
312	continue;
313	default:
314	return 0;
315	}
316	}
317
318	return 0;
319	}
320
321	/**
322	* sk_chk_filter - verify socket filter code
323	* @filter: filter to verify
324	* @flen: length of filter
325	*
326	* Check the user's filter code. If we let some ugly
327	* filter code slip through kaboom! The filter must contain
328	* no references or jumps that are out of range, no illegal instructions
329	* and no backward jumps. It must end with a RET instruction
330	*
331	* Returns 0 if the rule set is legal or a negative errno code if not.
332	*/
333	int sk_chk_filter(struct sock_filter *filter, int flen)
334	{
335	struct sock_filter *ftest;
336	int pc;
337
338	if (((unsigned int)flen >= (~0U / sizeof(struct sock_filter))) \|\| flen == 0)
339	return -EINVAL;
340
341	/* check the filter code now */
342	for (pc = 0; pc < flen; pc++) {
343	/* all jumps are forward as they are not signed */
344	ftest = &filter[pc];
345	if (BPF_CLASS(ftest->code) == BPF_JMP) {
346	/* but they mustn't jump off the end */
347	if (BPF_OP(ftest->code) == BPF_JA) {
348	/*
349	* Note, the large ftest->k might cause loops.
350	* Compare this with conditional jumps below,
351	* where offsets are limited. --ANK (981016)
352	*/
353	if (ftest->k >= (unsigned)(flen-pc-1))
354	return -EINVAL;
355	} else {
356	/* for conditionals both must be safe */
357	if (pc + ftest->jt +1 >= flen \|\|
358	pc + ftest->jf +1 >= flen)
359	return -EINVAL;
360	}
361	}
362
363	/* check that memory operations use valid addresses. */
364	if (ftest->k >= BPF_MEMWORDS) {
365	/* but it might not be a memory operation... */
366	switch (ftest->code) {
367	case BPF_ST:
368	case BPF_STX:
369	case BPF_LD\|BPF_MEM:
370	case BPF_LDX\|BPF_MEM:
371	return -EINVAL;
372	}
373	}
374	}
375
376	/*
377	* The program must end with a return. We don't care where they
378	* jumped within the script (its always forwards) but in the end
379	* they _will_ hit this.
380	*/
381	return (BPF_CLASS(filter[flen - 1].code) == BPF_RET) ? 0 : -EINVAL;
382	}
383
384	/**
385	* sk_attach_filter - attach a socket filter
386	* @fprog: the filter program
387	* @sk: the socket to use
388	*
389	* Attach the user's filter code. We first run some sanity checks on
390	* it to make sure it does not explode on us later. If an error
391	* occurs or there is insufficient memory for the filter a negative
392	* errno code is returned. On success the return is zero.
393	*/
394	int sk_attach_filter(struct sock_fprog fprog, struct sock sk)
395	{
396	struct sk_filter *fp;
397	unsigned int fsize = sizeof(struct sock_filter) * fprog->len;
398	int err;
399
400	/* Make sure new filter is there and in the right amounts. */
401	if (fprog->filter == NULL \|\| fprog->len > BPF_MAXINSNS)
402	return -EINVAL;
403
404	fp = sock_kmalloc(sk, fsize+sizeof(*fp), GFP_KERNEL);
405	if (!fp)
406	return -ENOMEM;
407	if (copy_from_user(fp->insns, fprog->filter, fsize)) {
408	sock_kfree_s(sk, fp, fsize+sizeof(*fp));
409	return -EFAULT;
410	}
411
412	atomic_set(&fp->refcnt, 1);
413	fp->len = fprog->len;
414
415	err = sk_chk_filter(fp->insns, fp->len);
416	if (!err) {
417	struct sk_filter *old_fp;
418
419	spin_lock_bh(&sk->sk_lock.slock);
420	old_fp = sk->sk_filter;
421	sk->sk_filter = fp;
422	spin_unlock_bh(&sk->sk_lock.slock);
423	fp = old_fp;
424	}
425
426	if (fp)
427	sk_filter_release(sk, fp);
428	return err;
429	}
430
431	EXPORT_SYMBOL(sk_chk_filter);
432	EXPORT_SYMBOL(sk_run_filter);