mirror of
https://github.com/team-infusion-developers/android_kernel_samsung_msm8976.git
synced 2024-10-20 10:28:24 +00:00
1da177e4c3
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
432 lines
9.8 KiB
C
432 lines
9.8 KiB
C
/*
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* Linux Socket Filter - Kernel level socket filtering
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*
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* Author:
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* Jay Schulist <jschlst@samba.org>
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*
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* Based on the design of:
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* - The Berkeley Packet Filter
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* Andi Kleen - Fix a few bad bugs and races.
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*/
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/sched.h>
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#include <linux/mm.h>
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#include <linux/fcntl.h>
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#include <linux/socket.h>
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#include <linux/in.h>
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#include <linux/inet.h>
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#include <linux/netdevice.h>
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#include <linux/if_packet.h>
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#include <net/ip.h>
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#include <net/protocol.h>
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#include <linux/skbuff.h>
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#include <net/sock.h>
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#include <linux/errno.h>
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#include <linux/timer.h>
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#include <asm/system.h>
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#include <asm/uaccess.h>
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#include <linux/filter.h>
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/* No hurry in this branch */
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static u8 *load_pointer(struct sk_buff *skb, int k)
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{
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u8 *ptr = NULL;
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if (k >= SKF_NET_OFF)
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ptr = skb->nh.raw + k - SKF_NET_OFF;
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else if (k >= SKF_LL_OFF)
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ptr = skb->mac.raw + k - SKF_LL_OFF;
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if (ptr >= skb->head && ptr < skb->tail)
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return ptr;
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return NULL;
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}
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/**
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* sk_run_filter - run a filter on a socket
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* @skb: buffer to run the filter on
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* @filter: filter to apply
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* @flen: length of filter
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*
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* Decode and apply filter instructions to the skb->data.
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* Return length to keep, 0 for none. skb is the data we are
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* filtering, filter is the array of filter instructions, and
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* len is the number of filter blocks in the array.
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*/
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int sk_run_filter(struct sk_buff *skb, struct sock_filter *filter, int flen)
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{
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unsigned char *data = skb->data;
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/* len is UNSIGNED. Byte wide insns relies only on implicit
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type casts to prevent reading arbitrary memory locations.
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*/
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unsigned int len = skb->len-skb->data_len;
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struct sock_filter *fentry; /* We walk down these */
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u32 A = 0; /* Accumulator */
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u32 X = 0; /* Index Register */
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u32 mem[BPF_MEMWORDS]; /* Scratch Memory Store */
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int k;
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int pc;
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/*
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* Process array of filter instructions.
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*/
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for (pc = 0; pc < flen; pc++) {
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fentry = &filter[pc];
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switch (fentry->code) {
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case BPF_ALU|BPF_ADD|BPF_X:
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A += X;
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continue;
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case BPF_ALU|BPF_ADD|BPF_K:
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A += fentry->k;
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continue;
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case BPF_ALU|BPF_SUB|BPF_X:
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A -= X;
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continue;
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case BPF_ALU|BPF_SUB|BPF_K:
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A -= fentry->k;
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continue;
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case BPF_ALU|BPF_MUL|BPF_X:
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A *= X;
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continue;
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case BPF_ALU|BPF_MUL|BPF_K:
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A *= fentry->k;
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continue;
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case BPF_ALU|BPF_DIV|BPF_X:
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if (X == 0)
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return 0;
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A /= X;
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continue;
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case BPF_ALU|BPF_DIV|BPF_K:
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if (fentry->k == 0)
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return 0;
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A /= fentry->k;
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continue;
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case BPF_ALU|BPF_AND|BPF_X:
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A &= X;
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continue;
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case BPF_ALU|BPF_AND|BPF_K:
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A &= fentry->k;
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continue;
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case BPF_ALU|BPF_OR|BPF_X:
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A |= X;
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continue;
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case BPF_ALU|BPF_OR|BPF_K:
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A |= fentry->k;
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continue;
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case BPF_ALU|BPF_LSH|BPF_X:
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A <<= X;
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continue;
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case BPF_ALU|BPF_LSH|BPF_K:
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A <<= fentry->k;
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continue;
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case BPF_ALU|BPF_RSH|BPF_X:
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A >>= X;
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continue;
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case BPF_ALU|BPF_RSH|BPF_K:
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A >>= fentry->k;
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continue;
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case BPF_ALU|BPF_NEG:
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A = -A;
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continue;
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case BPF_JMP|BPF_JA:
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pc += fentry->k;
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continue;
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case BPF_JMP|BPF_JGT|BPF_K:
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pc += (A > fentry->k) ? fentry->jt : fentry->jf;
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continue;
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case BPF_JMP|BPF_JGE|BPF_K:
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pc += (A >= fentry->k) ? fentry->jt : fentry->jf;
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continue;
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case BPF_JMP|BPF_JEQ|BPF_K:
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pc += (A == fentry->k) ? fentry->jt : fentry->jf;
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continue;
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case BPF_JMP|BPF_JSET|BPF_K:
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pc += (A & fentry->k) ? fentry->jt : fentry->jf;
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continue;
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case BPF_JMP|BPF_JGT|BPF_X:
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pc += (A > X) ? fentry->jt : fentry->jf;
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continue;
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case BPF_JMP|BPF_JGE|BPF_X:
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pc += (A >= X) ? fentry->jt : fentry->jf;
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continue;
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case BPF_JMP|BPF_JEQ|BPF_X:
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pc += (A == X) ? fentry->jt : fentry->jf;
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continue;
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case BPF_JMP|BPF_JSET|BPF_X:
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pc += (A & X) ? fentry->jt : fentry->jf;
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continue;
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case BPF_LD|BPF_W|BPF_ABS:
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k = fentry->k;
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load_w:
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if (k >= 0 && (unsigned int)(k+sizeof(u32)) <= len) {
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A = ntohl(*(u32*)&data[k]);
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continue;
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}
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if (k < 0) {
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u8 *ptr;
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if (k >= SKF_AD_OFF)
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break;
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ptr = load_pointer(skb, k);
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if (ptr) {
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A = ntohl(*(u32*)ptr);
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continue;
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}
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} else {
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u32 _tmp, *p;
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p = skb_header_pointer(skb, k, 4, &_tmp);
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if (p != NULL) {
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A = ntohl(*p);
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continue;
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}
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}
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return 0;
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case BPF_LD|BPF_H|BPF_ABS:
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k = fentry->k;
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load_h:
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if (k >= 0 && (unsigned int)(k + sizeof(u16)) <= len) {
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A = ntohs(*(u16*)&data[k]);
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continue;
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}
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if (k < 0) {
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u8 *ptr;
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if (k >= SKF_AD_OFF)
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break;
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ptr = load_pointer(skb, k);
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if (ptr) {
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A = ntohs(*(u16*)ptr);
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continue;
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}
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} else {
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u16 _tmp, *p;
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p = skb_header_pointer(skb, k, 2, &_tmp);
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if (p != NULL) {
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A = ntohs(*p);
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continue;
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}
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}
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return 0;
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case BPF_LD|BPF_B|BPF_ABS:
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k = fentry->k;
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load_b:
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if (k >= 0 && (unsigned int)k < len) {
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A = data[k];
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continue;
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}
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if (k < 0) {
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u8 *ptr;
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if (k >= SKF_AD_OFF)
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break;
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ptr = load_pointer(skb, k);
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if (ptr) {
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A = *ptr;
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continue;
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}
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} else {
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u8 _tmp, *p;
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p = skb_header_pointer(skb, k, 1, &_tmp);
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if (p != NULL) {
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A = *p;
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continue;
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}
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}
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return 0;
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case BPF_LD|BPF_W|BPF_LEN:
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A = len;
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continue;
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case BPF_LDX|BPF_W|BPF_LEN:
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X = len;
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continue;
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case BPF_LD|BPF_W|BPF_IND:
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k = X + fentry->k;
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goto load_w;
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case BPF_LD|BPF_H|BPF_IND:
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k = X + fentry->k;
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goto load_h;
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case BPF_LD|BPF_B|BPF_IND:
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k = X + fentry->k;
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goto load_b;
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case BPF_LDX|BPF_B|BPF_MSH:
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if (fentry->k >= len)
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return 0;
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X = (data[fentry->k] & 0xf) << 2;
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continue;
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case BPF_LD|BPF_IMM:
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A = fentry->k;
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continue;
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case BPF_LDX|BPF_IMM:
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X = fentry->k;
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continue;
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case BPF_LD|BPF_MEM:
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A = mem[fentry->k];
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continue;
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case BPF_LDX|BPF_MEM:
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X = mem[fentry->k];
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continue;
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case BPF_MISC|BPF_TAX:
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X = A;
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continue;
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case BPF_MISC|BPF_TXA:
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A = X;
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continue;
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case BPF_RET|BPF_K:
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return ((unsigned int)fentry->k);
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case BPF_RET|BPF_A:
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return ((unsigned int)A);
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case BPF_ST:
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mem[fentry->k] = A;
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continue;
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case BPF_STX:
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mem[fentry->k] = X;
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continue;
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default:
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/* Invalid instruction counts as RET */
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return 0;
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}
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/*
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* Handle ancillary data, which are impossible
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* (or very difficult) to get parsing packet contents.
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*/
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switch (k-SKF_AD_OFF) {
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case SKF_AD_PROTOCOL:
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A = htons(skb->protocol);
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continue;
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case SKF_AD_PKTTYPE:
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A = skb->pkt_type;
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continue;
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case SKF_AD_IFINDEX:
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A = skb->dev->ifindex;
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continue;
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default:
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return 0;
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}
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}
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return 0;
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}
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/**
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* sk_chk_filter - verify socket filter code
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* @filter: filter to verify
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* @flen: length of filter
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*
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* Check the user's filter code. If we let some ugly
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* filter code slip through kaboom! The filter must contain
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* no references or jumps that are out of range, no illegal instructions
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* and no backward jumps. It must end with a RET instruction
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*
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* Returns 0 if the rule set is legal or a negative errno code if not.
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*/
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int sk_chk_filter(struct sock_filter *filter, int flen)
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{
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struct sock_filter *ftest;
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int pc;
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if (((unsigned int)flen >= (~0U / sizeof(struct sock_filter))) || flen == 0)
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return -EINVAL;
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/* check the filter code now */
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for (pc = 0; pc < flen; pc++) {
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/* all jumps are forward as they are not signed */
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ftest = &filter[pc];
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if (BPF_CLASS(ftest->code) == BPF_JMP) {
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/* but they mustn't jump off the end */
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if (BPF_OP(ftest->code) == BPF_JA) {
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/*
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* Note, the large ftest->k might cause loops.
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* Compare this with conditional jumps below,
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* where offsets are limited. --ANK (981016)
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*/
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if (ftest->k >= (unsigned)(flen-pc-1))
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return -EINVAL;
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} else {
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/* for conditionals both must be safe */
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if (pc + ftest->jt +1 >= flen ||
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pc + ftest->jf +1 >= flen)
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return -EINVAL;
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}
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}
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/* check that memory operations use valid addresses. */
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if (ftest->k >= BPF_MEMWORDS) {
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/* but it might not be a memory operation... */
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switch (ftest->code) {
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case BPF_ST:
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case BPF_STX:
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case BPF_LD|BPF_MEM:
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case BPF_LDX|BPF_MEM:
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return -EINVAL;
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}
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}
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}
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/*
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* The program must end with a return. We don't care where they
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* jumped within the script (its always forwards) but in the end
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* they _will_ hit this.
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*/
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return (BPF_CLASS(filter[flen - 1].code) == BPF_RET) ? 0 : -EINVAL;
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}
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/**
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* sk_attach_filter - attach a socket filter
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* @fprog: the filter program
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* @sk: the socket to use
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*
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* Attach the user's filter code. We first run some sanity checks on
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* it to make sure it does not explode on us later. If an error
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* occurs or there is insufficient memory for the filter a negative
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* errno code is returned. On success the return is zero.
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*/
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int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk)
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{
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struct sk_filter *fp;
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unsigned int fsize = sizeof(struct sock_filter) * fprog->len;
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int err;
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/* Make sure new filter is there and in the right amounts. */
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if (fprog->filter == NULL || fprog->len > BPF_MAXINSNS)
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return -EINVAL;
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fp = sock_kmalloc(sk, fsize+sizeof(*fp), GFP_KERNEL);
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if (!fp)
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return -ENOMEM;
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if (copy_from_user(fp->insns, fprog->filter, fsize)) {
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sock_kfree_s(sk, fp, fsize+sizeof(*fp));
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return -EFAULT;
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}
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atomic_set(&fp->refcnt, 1);
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fp->len = fprog->len;
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err = sk_chk_filter(fp->insns, fp->len);
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if (!err) {
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struct sk_filter *old_fp;
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spin_lock_bh(&sk->sk_lock.slock);
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old_fp = sk->sk_filter;
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sk->sk_filter = fp;
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spin_unlock_bh(&sk->sk_lock.slock);
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fp = old_fp;
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}
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if (fp)
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sk_filter_release(sk, fp);
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return err;
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}
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EXPORT_SYMBOL(sk_chk_filter);
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EXPORT_SYMBOL(sk_run_filter);
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