* 2 of the License, or (at your option) any later version.
*
* Andi Kleen - Fix a few bad bugs and races.
+ * Kris Katterjohn - Added many additional checks in sk_chk_filter()
*/
#include <linux/module.h>
#include <linux/timer.h>
#include <asm/system.h>
#include <asm/uaccess.h>
+#include <asm/unaligned.h>
#include <linux/filter.h>
/* No hurry in this branch */
-static u8 *load_pointer(struct sk_buff *skb, int k)
+static void *__load_pointer(struct sk_buff *skb, int k)
{
u8 *ptr = NULL;
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
+ * sk_run_filter - run a filter on a socket
* @skb: buffer to run the filter on
* @filter: filter to apply
* @flen: length of filter
* 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 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 */
+ void *ptr;
+ u32 A = 0; /* Accumulator */
+ u32 X = 0; /* Index Register */
u32 mem[BPF_MEMWORDS]; /* Scratch Memory Store */
+ u32 tmp;
int k;
int pc;
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:
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]);
+load_w:
+ ptr = load_pointer(skb, k, 4, &tmp);
+ if (ptr != NULL) {
+ A = ntohl(get_unaligned((u32 *)ptr));
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;
+ break;
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]);
+load_h:
+ ptr = load_pointer(skb, k, 2, &tmp);
+ if (ptr != NULL) {
+ A = ntohs(get_unaligned((u16 *)ptr));
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;
+ break;
case BPF_LD|BPF_B|BPF_ABS:
k = fentry->k;
load_b:
- if (k >= 0 && (unsigned int)k < len) {
- A = data[k];
+ ptr = load_pointer(skb, k, 1, &tmp);
+ if (ptr != NULL) {
+ A = *(u8 *)ptr;
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;
+ break;
case BPF_LD|BPF_W|BPF_LEN:
- A = len;
+ A = skb->len;
continue;
case BPF_LDX|BPF_W|BPF_LEN:
- X = len;
+ X = skb->len;
continue;
case BPF_LD|BPF_W|BPF_IND:
k = X + fentry->k;
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;
+ 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;
A = X;
continue;
case BPF_RET|BPF_K:
- return ((unsigned int)fentry->k);
+ return fentry->k;
case BPF_RET|BPF_A:
- return ((unsigned int)A);
+ return A;
case BPF_ST:
mem[fentry->k] = A;
continue;
mem[fentry->k] = X;
continue;
default:
- /* Invalid instruction counts as RET */
+ WARN_ON(1);
return 0;
}
*
* 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
+ * no references or jumps that are out of range, no illegal
+ * instructions, and must end with a RET instruction.
+ *
+ * All jumps are forward as they are not signed.
*
- * Returns 0 if the rule set is legal or a negative errno code if not.
+ * Returns 0 if the rule set is legal or -EINVAL 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)
+ if (flen == 0 || flen > BPF_MAXINSNS)
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:
+ /* Only allow valid instructions */
+ switch (ftest->code) {
+ case BPF_ALU|BPF_ADD|BPF_K:
+ case BPF_ALU|BPF_ADD|BPF_X:
+ case BPF_ALU|BPF_SUB|BPF_K:
+ case BPF_ALU|BPF_SUB|BPF_X:
+ case BPF_ALU|BPF_MUL|BPF_K:
+ case BPF_ALU|BPF_MUL|BPF_X:
+ case BPF_ALU|BPF_DIV|BPF_X:
+ case BPF_ALU|BPF_AND|BPF_K:
+ case BPF_ALU|BPF_AND|BPF_X:
+ case BPF_ALU|BPF_OR|BPF_K:
+ case BPF_ALU|BPF_OR|BPF_X:
+ case BPF_ALU|BPF_LSH|BPF_K:
+ case BPF_ALU|BPF_LSH|BPF_X:
+ case BPF_ALU|BPF_RSH|BPF_K:
+ case BPF_ALU|BPF_RSH|BPF_X:
+ case BPF_ALU|BPF_NEG:
+ case BPF_LD|BPF_W|BPF_ABS:
+ case BPF_LD|BPF_H|BPF_ABS:
+ case BPF_LD|BPF_B|BPF_ABS:
+ case BPF_LD|BPF_W|BPF_LEN:
+ case BPF_LD|BPF_W|BPF_IND:
+ case BPF_LD|BPF_H|BPF_IND:
+ case BPF_LD|BPF_B|BPF_IND:
+ case BPF_LD|BPF_IMM:
+ case BPF_LDX|BPF_W|BPF_LEN:
+ case BPF_LDX|BPF_B|BPF_MSH:
+ case BPF_LDX|BPF_IMM:
+ case BPF_MISC|BPF_TAX:
+ case BPF_MISC|BPF_TXA:
+ case BPF_RET|BPF_K:
+ case BPF_RET|BPF_A:
+ break;
+
+ /* Some instructions need special checks */
+
+ case BPF_ALU|BPF_DIV|BPF_K:
+ /* check for division by zero */
+ if (ftest->k == 0)
return -EINVAL;
- }
+ break;
+
+ case BPF_LD|BPF_MEM:
+ case BPF_LDX|BPF_MEM:
+ case BPF_ST:
+ case BPF_STX:
+ /* check for invalid memory addresses */
+ if (ftest->k >= BPF_MEMWORDS)
+ return -EINVAL;
+ break;
+
+ case BPF_JMP|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;
+ break;
+
+ case BPF_JMP|BPF_JEQ|BPF_K:
+ case BPF_JMP|BPF_JEQ|BPF_X:
+ case BPF_JMP|BPF_JGE|BPF_K:
+ case BPF_JMP|BPF_JGE|BPF_X:
+ case BPF_JMP|BPF_JGT|BPF_K:
+ case BPF_JMP|BPF_JGT|BPF_X:
+ case BPF_JMP|BPF_JSET|BPF_K:
+ case BPF_JMP|BPF_JSET|BPF_X:
+ /* for conditionals both must be safe */
+ if (pc + ftest->jt + 1 >= flen ||
+ pc + ftest->jf + 1 >= flen)
+ return -EINVAL;
+ break;
+
+ default:
+ 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;
+ return (BPF_CLASS(filter[flen - 1].code) == BPF_RET) ? 0 : -EINVAL;
}
/**
int err;
/* Make sure new filter is there and in the right amounts. */
- if (fprog->filter == NULL || fprog->len > BPF_MAXINSNS)
- return -EINVAL;
+ if (fprog->filter == NULL)
+ return -EINVAL;
fp = sock_kmalloc(sk, fsize+sizeof(*fp), GFP_KERNEL);
if (!fp)
git://git.onelab.eu / linux-2.6.git / blobdiff