summaryrefslogtreecommitdiff
path: root/pfinet/linux-src/net/core/filter.c
diff options
context:
space:
mode:
Diffstat (limited to 'pfinet/linux-src/net/core/filter.c')
-rw-r--r--pfinet/linux-src/net/core/filter.c454
1 files changed, 454 insertions, 0 deletions
diff --git a/pfinet/linux-src/net/core/filter.c b/pfinet/linux-src/net/core/filter.c
new file mode 100644
index 00000000..8e1ffb62
--- /dev/null
+++ b/pfinet/linux-src/net/core/filter.c
@@ -0,0 +1,454 @@
+/*
+ * Linux Socket Filter - Kernel level socket filtering
+ *
+ * Author:
+ * Jay Schulist <Jay.Schulist@spacs.k12.wi.us>
+ *
+ * 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/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>
+
+/* 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;
+}
+
+/*
+ * 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;
+ 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+sizeof(u32) <= len) {
+ A = ntohl(*(u32*)&data[k]);
+ continue;
+ }
+ if (k<0) {
+ u8 *ptr;
+
+ if (k>=SKF_AD_OFF)
+ break;
+ if ((ptr = load_pointer(skb, k)) != NULL) {
+ A = ntohl(*(u32*)ptr);
+ continue;
+ }
+ }
+ return 0;
+
+ case BPF_LD|BPF_H|BPF_ABS:
+ k = fentry->k;
+load_h:
+ if(k + sizeof(u16) <= len) {
+ A = ntohs(*(u16*)&data[k]);
+ continue;
+ }
+ if (k<0) {
+ u8 *ptr;
+
+ if (k>=SKF_AD_OFF)
+ break;
+ if ((ptr = load_pointer(skb, k)) != NULL) {
+ A = ntohs(*(u16*)ptr);
+ continue;
+ }
+ }
+ return 0;
+
+ case BPF_LD|BPF_B|BPF_ABS:
+ k = fentry->k;
+load_b:
+ if(k < len) {
+ A = data[k];
+ continue;
+ }
+ if (k<0) {
+ u8 *ptr;
+
+ if (k>=SKF_AD_OFF)
+ break;
+ if ((ptr = load_pointer(skb, k)) != NULL) {
+ A = *ptr;
+ 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;
+ 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:
+ k = fentry->k;
+ if(k >= len)
+ return (0);
+ X = (data[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);
+}
+
+/*
+ * 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)
+ {
+ /* 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;
+}
+
+/*
+ * 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 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 = (struct sk_filter *)sock_kmalloc(sk, fsize+sizeof(*fp), GFP_KERNEL);
+ if(fp == NULL)
+ 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;
+
+ if ((err = sk_chk_filter(fp->insns, fp->len))==0) {
+ struct sk_filter *old_fp = sk->filter;
+ sk->filter = fp;
+ synchronize_bh();
+ fp = old_fp;
+ }
+
+ if (fp)
+ sk_filter_release(sk, fp);
+
+ return (err);
+}
+#endif /* CONFIG_FILTER */
generated by cgit v1.2.3 (git 2.39.1) at 2024-09-01 15:36:27 +0000