1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Generic netlink handshake service 4 * 5 * Author: Chuck Lever <chuck.lever@oracle.com> 6 * 7 * Copyright (c) 2023, Oracle and/or its affiliates. 8 */ 9 10 #include <linux/types.h> 11 #include <linux/socket.h> 12 #include <linux/kernel.h> 13 #include <linux/module.h> 14 #include <linux/skbuff.h> 15 #include <linux/mm.h> 16 17 #include <net/sock.h> 18 #include <net/genetlink.h> 19 #include <net/netns/generic.h> 20 21 #include <kunit/visibility.h> 22 23 #include <uapi/linux/handshake.h> 24 #include "handshake.h" 25 #include "genl.h" 26 27 #include <trace/events/handshake.h> 28 29 /** 30 * handshake_genl_notify - Notify handlers that a request is waiting 31 * @net: target network namespace 32 * @proto: handshake protocol 33 * @flags: memory allocation control flags 34 * 35 * Returns zero on success or a negative errno if notification failed. 36 */ 37 int handshake_genl_notify(struct net *net, const struct handshake_proto *proto, 38 gfp_t flags) 39 { 40 struct sk_buff *msg; 41 void *hdr; 42 43 /* Disable notifications during unit testing */ 44 if (!test_bit(HANDSHAKE_F_PROTO_NOTIFY, &proto->hp_flags)) 45 return 0; 46 47 if (!genl_has_listeners(&handshake_nl_family, net, 48 proto->hp_handler_class)) 49 return -ESRCH; 50 51 msg = genlmsg_new(GENLMSG_DEFAULT_SIZE, flags); 52 if (!msg) 53 return -ENOMEM; 54 55 hdr = genlmsg_put(msg, 0, 0, &handshake_nl_family, 0, 56 HANDSHAKE_CMD_READY); 57 if (!hdr) 58 goto out_free; 59 60 if (nla_put_u32(msg, HANDSHAKE_A_ACCEPT_HANDLER_CLASS, 61 proto->hp_handler_class) < 0) { 62 genlmsg_cancel(msg, hdr); 63 goto out_free; 64 } 65 66 genlmsg_end(msg, hdr); 67 return genlmsg_multicast_netns(&handshake_nl_family, net, msg, 68 0, proto->hp_handler_class, flags); 69 70 out_free: 71 nlmsg_free(msg); 72 return -EMSGSIZE; 73 } 74 75 /** 76 * handshake_genl_put - Create a generic netlink message header 77 * @msg: buffer in which to create the header 78 * @info: generic netlink message context 79 * 80 * Returns a ready-to-use header, or NULL. 81 */ 82 struct nlmsghdr *handshake_genl_put(struct sk_buff *msg, 83 struct genl_info *info) 84 { 85 return genlmsg_put(msg, info->snd_portid, info->snd_seq, 86 &handshake_nl_family, 0, info->genlhdr->cmd); 87 } 88 EXPORT_SYMBOL(handshake_genl_put); 89 90 /* 91 * dup() a kernel socket for use as a user space file descriptor 92 * in the current process. The kernel socket must have an 93 * instatiated struct file. 94 * 95 * Implicit argument: "current()" 96 */ 97 static int handshake_dup(struct socket *sock) 98 { 99 struct file *file; 100 int newfd; 101 102 file = get_file(sock->file); 103 newfd = get_unused_fd_flags(O_CLOEXEC); 104 if (newfd < 0) { 105 fput(file); 106 return newfd; 107 } 108 109 fd_install(newfd, file); 110 return newfd; 111 } 112 113 int handshake_nl_accept_doit(struct sk_buff *skb, struct genl_info *info) 114 { 115 struct net *net = sock_net(skb->sk); 116 struct handshake_net *hn = handshake_pernet(net); 117 struct handshake_req *req = NULL; 118 struct socket *sock; 119 int class, fd, err; 120 121 err = -EOPNOTSUPP; 122 if (!hn) 123 goto out_status; 124 125 err = -EINVAL; 126 if (GENL_REQ_ATTR_CHECK(info, HANDSHAKE_A_ACCEPT_HANDLER_CLASS)) 127 goto out_status; 128 class = nla_get_u32(info->attrs[HANDSHAKE_A_ACCEPT_HANDLER_CLASS]); 129 130 err = -EAGAIN; 131 req = handshake_req_next(hn, class); 132 if (!req) 133 goto out_status; 134 135 sock = req->hr_sk->sk_socket; 136 fd = handshake_dup(sock); 137 if (fd < 0) { 138 err = fd; 139 goto out_complete; 140 } 141 err = req->hr_proto->hp_accept(req, info, fd); 142 if (err) { 143 fput(sock->file); 144 goto out_complete; 145 } 146 147 trace_handshake_cmd_accept(net, req, req->hr_sk, fd); 148 return 0; 149 150 out_complete: 151 handshake_complete(req, -EIO, NULL); 152 out_status: 153 trace_handshake_cmd_accept_err(net, req, NULL, err); 154 return err; 155 } 156 157 int handshake_nl_done_doit(struct sk_buff *skb, struct genl_info *info) 158 { 159 struct net *net = sock_net(skb->sk); 160 struct handshake_req *req = NULL; 161 struct socket *sock = NULL; 162 int fd, status, err; 163 164 if (GENL_REQ_ATTR_CHECK(info, HANDSHAKE_A_DONE_SOCKFD)) 165 return -EINVAL; 166 fd = nla_get_u32(info->attrs[HANDSHAKE_A_DONE_SOCKFD]); 167 168 err = 0; 169 sock = sockfd_lookup(fd, &err); 170 if (err) { 171 err = -EBADF; 172 goto out_status; 173 } 174 175 req = handshake_req_hash_lookup(sock->sk); 176 if (!req) { 177 err = -EBUSY; 178 fput(sock->file); 179 goto out_status; 180 } 181 182 trace_handshake_cmd_done(net, req, sock->sk, fd); 183 184 status = -EIO; 185 if (info->attrs[HANDSHAKE_A_DONE_STATUS]) 186 status = nla_get_u32(info->attrs[HANDSHAKE_A_DONE_STATUS]); 187 188 handshake_complete(req, status, info); 189 fput(sock->file); 190 return 0; 191 192 out_status: 193 trace_handshake_cmd_done_err(net, req, sock->sk, err); 194 return err; 195 } 196 197 static unsigned int handshake_net_id; 198 199 static int __net_init handshake_net_init(struct net *net) 200 { 201 struct handshake_net *hn = net_generic(net, handshake_net_id); 202 unsigned long tmp; 203 struct sysinfo si; 204 205 /* 206 * Arbitrary limit to prevent handshakes that do not make 207 * progress from clogging up the system. The cap scales up 208 * with the amount of physical memory on the system. 209 */ 210 si_meminfo(&si); 211 tmp = si.totalram / (25 * si.mem_unit); 212 hn->hn_pending_max = clamp(tmp, 3UL, 50UL); 213 214 spin_lock_init(&hn->hn_lock); 215 hn->hn_pending = 0; 216 hn->hn_flags = 0; 217 INIT_LIST_HEAD(&hn->hn_requests); 218 return 0; 219 } 220 221 static void __net_exit handshake_net_exit(struct net *net) 222 { 223 struct handshake_net *hn = net_generic(net, handshake_net_id); 224 struct handshake_req *req; 225 LIST_HEAD(requests); 226 227 /* 228 * Drain the net's pending list. Requests that have been 229 * accepted and are in progress will be destroyed when 230 * the socket is closed. 231 */ 232 spin_lock(&hn->hn_lock); 233 set_bit(HANDSHAKE_F_NET_DRAINING, &hn->hn_flags); 234 list_splice_init(&requests, &hn->hn_requests); 235 spin_unlock(&hn->hn_lock); 236 237 while (!list_empty(&requests)) { 238 req = list_first_entry(&requests, struct handshake_req, hr_list); 239 list_del(&req->hr_list); 240 241 /* 242 * Requests on this list have not yet been 243 * accepted, so they do not have an fd to put. 244 */ 245 246 handshake_complete(req, -ETIMEDOUT, NULL); 247 } 248 } 249 250 static struct pernet_operations handshake_genl_net_ops = { 251 .init = handshake_net_init, 252 .exit = handshake_net_exit, 253 .id = &handshake_net_id, 254 .size = sizeof(struct handshake_net), 255 }; 256 257 /** 258 * handshake_pernet - Get the handshake private per-net structure 259 * @net: network namespace 260 * 261 * Returns a pointer to the net's private per-net structure for the 262 * handshake module, or NULL if handshake_init() failed. 263 */ 264 struct handshake_net *handshake_pernet(struct net *net) 265 { 266 return handshake_net_id ? 267 net_generic(net, handshake_net_id) : NULL; 268 } 269 EXPORT_SYMBOL_IF_KUNIT(handshake_pernet); 270 271 static int __init handshake_init(void) 272 { 273 int ret; 274 275 ret = handshake_req_hash_init(); 276 if (ret) { 277 pr_warn("handshake: hash initialization failed (%d)\n", ret); 278 return ret; 279 } 280 281 ret = genl_register_family(&handshake_nl_family); 282 if (ret) { 283 pr_warn("handshake: netlink registration failed (%d)\n", ret); 284 handshake_req_hash_destroy(); 285 return ret; 286 } 287 288 /* 289 * ORDER: register_pernet_subsys must be done last. 290 * 291 * If initialization does not make it past pernet_subsys 292 * registration, then handshake_net_id will remain 0. That 293 * shunts the handshake consumer API to return ENOTSUPP 294 * to prevent it from dereferencing something that hasn't 295 * been allocated. 296 */ 297 ret = register_pernet_subsys(&handshake_genl_net_ops); 298 if (ret) { 299 pr_warn("handshake: pernet registration failed (%d)\n", ret); 300 genl_unregister_family(&handshake_nl_family); 301 handshake_req_hash_destroy(); 302 } 303 304 return ret; 305 } 306 307 static void __exit handshake_exit(void) 308 { 309 unregister_pernet_subsys(&handshake_genl_net_ops); 310 handshake_net_id = 0; 311 312 handshake_req_hash_destroy(); 313 genl_unregister_family(&handshake_nl_family); 314 } 315 316 module_init(handshake_init); 317 module_exit(handshake_exit); 318