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[NET]: More instruction checks fornet/core/filter.c

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Signed-off-by: Kris Katterjohn <kjak@users.sourceforge.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Kris Katterjohn 2006-01-04 13:58:36 -08:00 committed by David S. Miller
parent 181a46a56e
commit 9369986306
1 changed files with 80 additions and 32 deletions
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112
net/core/filter.c
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@ -13,6 +13,7 @@
* 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>
@ -250,7 +251,7 @@ load_b:
mem[fentry->k] = X;
continue;
default:
/* Invalid instruction counts as RET */
WARN_ON(1);
return 0;
}
@ -283,8 +284,8 @@ load_b:
*
* 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.
*
* Returns 0 if the rule set is legal or a negative errno code if not.
*/
@ -300,38 +301,85 @@ int sk_chk_filter(struct sock_filter *filter, int flen)
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 for division by zero -Kris Katterjohn 2005-10-30 */
if (ftest->code == (BPF_ALU|BPF_DIV|BPF_K) && ftest->k == 0)
return -EINVAL;
/* 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;
/* 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:
/* 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;
}
}