[NET]: More instruction checks fornet/core/filter.c (93699863) · Commits · e / devices / android_kernel_fairphone_FP4

net/core/filter.c

+80 −32

Original line number	Diff line number	Diff line
		@@ -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 @@ int sk_run_filter(struct sk_buff skb, struct sock_filter filter, int flen)
		mem[fentry->k] = X;
		continue;
		default:
		/* Invalid instruction counts as RET */
		WARN_ON(1);
		return 0;
		}

		@@ -283,8 +284,8 @@ int sk_run_filter(struct sk_buff skb, struct sock_filter filter, int flen)
		*
		* 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.
		*/
		@@ -300,9 +301,60 @@ 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) {

		/* 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,
		@@ -310,30 +362,26 @@ int sk_chk_filter(struct sock_filter *filter, int flen)
		*/
		if (ftest->k >= (unsigned)(flen-pc-1))
		return -EINVAL;
		} else {
		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;
		}
		}

		/* check for division by zero -Kris Katterjohn 2005-10-30 */
		if (ftest->code == (BPF_ALU\|BPF_DIV\|BPF_K) && ftest->k == 0)
		return -EINVAL;
		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:
		default:
		return -EINVAL;
		}
		}
		}

		/*
		* The program must end with a return. We don't care where they