patch-2.1.75 linux/net/core/filter.c
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- Lines: 367
- Date:
Sun Dec 21 17:41:30 1997
- Orig file:
v2.1.74/linux/net/core/filter.c
- Orig date:
Wed Dec 31 16:00:00 1969
diff -u --recursive --new-file v2.1.74/linux/net/core/filter.c linux/net/core/filter.c
@@ -0,0 +1,366 @@
+/*
+ * Linux Socket Filter - Kernel level socket filtering
+ *
+ * Author:
+ * Jay Schulist <Jay.Schulist@spacs.k12.wi.us>
+ *
+ * Based on the design of:
+ * - The Berkely 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.
+ */
+
+#include <linux/config.h>
+#if defined(CONFIG_FILTER)
+
+#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>
+
+/*
+ * 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(unsigned char *data, int len, struct sock_filter *filter, int flen)
+{
+ 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;
+ int *t;
+
+ /*
+ * Process array of filter instructions.
+ */
+
+ for(pc = 0; pc < flen; pc++)
+ {
+ fentry = &filter[pc];
+ if(fentry->code & BPF_X)
+ t=&X;
+ else
+ t=&fentry->k;
+
+ switch(fentry->code)
+ {
+ case BPF_ALU|BPF_ADD|BPF_X:
+ case BPF_ALU|BPF_ADD|BPF_K:
+ A += *t;
+ continue;
+
+ case BPF_ALU|BPF_SUB|BPF_X:
+ case BPF_ALU|BPF_SUB|BPF_K:
+ A -= *t;
+ continue;
+
+ case BPF_ALU|BPF_MUL|BPF_X:
+ case BPF_ALU|BPF_MUL|BPF_K:
+ A *= *t;
+ continue;
+
+ case BPF_ALU|BPF_DIV|BPF_X:
+ case BPF_ALU|BPF_DIV|BPF_K:
+ if(*t == 0)
+ return (0);
+ A /= *t;
+ continue;
+
+ case BPF_ALU|BPF_AND|BPF_X:
+ case BPF_ALU|BPF_AND|BPF_K:
+ A &= *t;
+ continue;
+
+ case BPF_ALU|BPF_OR|BPF_X:
+ case BPF_ALU|BPF_OR|BPF_K:
+ A |= *t;
+ continue;
+
+ case BPF_ALU|BPF_LSH|BPF_X:
+ case BPF_ALU|BPF_LSH|BPF_K:
+ A <<= *t;
+ continue;
+
+ case BPF_ALU|BPF_RSH|BPF_X:
+ case BPF_ALU|BPF_RSH|BPF_K:
+ A >>= *t;
+ 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;
+ if(k + sizeof(long) > len)
+ return (0);
+ A = ntohl(*(long*)&data[k]);
+ continue;
+
+ case BPF_LD|BPF_H|BPF_ABS:
+ k = fentry->k;
+ if(k + sizeof(short) > len)
+ return (0);
+ A = ntohs(*(short*)&data[k]);
+ continue;
+
+ case BPF_LD|BPF_B|BPF_ABS:
+ k = fentry->k;
+ if(k >= len)
+ return (0);
+ A = data[k];
+ continue;
+
+ 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;
+ if(k + sizeof(u32) > len)
+ return (0);
+ A = ntohl(*(u32 *)&data[k]);
+ continue;
+
+ case BPF_LD|BPF_H|BPF_IND:
+ k = X + fentry->k;
+ if(k + sizeof(u16) > len)
+ return (0);
+ A = ntohs(*(u16*)&data[k]);
+ continue;
+
+ case BPF_LD|BPF_B|BPF_IND:
+ k = X + fentry->k;
+ if(k >= len)
+ return (0);
+ A = data[k];
+ continue;
+
+ case BPF_LDX|BPF_B|BPF_MSH:
+ /*
+ * Hack for BPF to handle TOS etc
+ */
+ k = fentry->k;
+ if(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);
+ }
+ }
+
+ printk(KERN_ERR "Filter ruleset ran off the end.\n");
+ return (0);
+}
+
+/*
+ * Check the user's filter code. If we let some ugly
+ * filter code slip through kaboom!
+ */
+
+int sk_chk_filter(struct sock_filter *filter, int flen)
+{
+ struct sock_filter *ftest;
+ int pc;
+
+ /*
+ * 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)
+ {
+ if(pc + ftest->k + 1>= (unsigned)flen)
+ 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 <0 || ftest->k >= BPF_MEMWORDS)
+ {
+ /*
+ * But it might not be a memory operation...
+ */
+
+ if (BPF_CLASS(ftest->code) == BPF_ST)
+ return -EINVAL;
+ if((BPF_CLASS(ftest->code) == BPF_LD) &&
+ (BPF_MODE(ftest->code) == 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);
+}
+
+/*
+ * Attach the user's filter code. We first run some sanity checks on
+ * it to make sure it does not explode on us later.
+ */
+
+int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk)
+{
+ struct sock_filter *fp, *old_filter;
+ 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 == 0 || fsize > BPF_MAXINSNS)
+ return (-EINVAL);
+
+ if((err = sk_chk_filter(fprog->filter, fprog->len)))
+ {
+ /* If existing filter, remove it first */
+ if(sk->filter)
+ {
+ old_filter = sk->filter_data;
+ kfree_s(old_filter, (sizeof(old_filter) * sk->filter));
+ sk->filter_data = NULL;
+ }
+
+ fp = (struct sock_filter *)kmalloc(fsize, GFP_KERNEL);
+ if(fp == NULL)
+ return (-ENOMEM);
+
+ memset(fp,0,sizeof(*fp));
+ memcpy(fp, fprog->filter, fsize); /* Copy instructions */
+
+ sk->filter = fprog->len; /* Number of filter blocks */
+ sk->filter_data = fp; /* Filter instructions */
+ }
+
+ return (err);
+}
+#endif /* CONFIG_FILTER */
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