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, GFP_KERNEL); 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 if (!sock->file) 103 return -EBADF; 104 105 file = get_file(sock->file); 106 newfd = get_unused_fd_flags(O_CLOEXEC); 107 if (newfd < 0) { 108 fput(file); 109 return newfd; 110 } 111 112 fd_install(newfd, file); 113 return newfd; 114 } 115 116 int handshake_nl_accept_doit(struct sk_buff *skb, struct genl_info *info) 117 { 118 struct net *net = sock_net(skb->sk); 119 struct handshake_net *hn = handshake_pernet(net); 120 struct handshake_req *req = NULL; 121 struct socket *sock; 122 int class, fd, err; 123 124 err = -EOPNOTSUPP; 125 if (!hn) 126 goto out_status; 127 128 err = -EINVAL; 129 if (GENL_REQ_ATTR_CHECK(info, HANDSHAKE_A_ACCEPT_HANDLER_CLASS)) 130 goto out_status; 131 class = nla_get_u32(info->attrs[HANDSHAKE_A_ACCEPT_HANDLER_CLASS]); 132 133 err = -EAGAIN; 134 req = handshake_req_next(hn, class); 135 if (!req) 136 goto out_status; 137 138 sock = req->hr_sk->sk_socket; 139 fd = handshake_dup(sock); 140 if (fd < 0) { 141 err = fd; 142 goto out_complete; 143 } 144 err = req->hr_proto->hp_accept(req, info, fd); 145 if (err) 146 goto out_complete; 147 148 trace_handshake_cmd_accept(net, req, req->hr_sk, fd); 149 return 0; 150 151 out_complete: 152 handshake_complete(req, -EIO, NULL); 153 fput(sock->file); 154 out_status: 155 trace_handshake_cmd_accept_err(net, req, NULL, err); 156 return err; 157 } 158 159 int handshake_nl_done_doit(struct sk_buff *skb, struct genl_info *info) 160 { 161 struct net *net = sock_net(skb->sk); 162 struct socket *sock = NULL; 163 struct handshake_req *req; 164 int fd, status, err; 165 166 if (GENL_REQ_ATTR_CHECK(info, HANDSHAKE_A_DONE_SOCKFD)) 167 return -EINVAL; 168 fd = nla_get_u32(info->attrs[HANDSHAKE_A_DONE_SOCKFD]); 169 170 err = 0; 171 sock = sockfd_lookup(fd, &err); 172 if (err) { 173 err = -EBADF; 174 goto out_status; 175 } 176 177 req = handshake_req_hash_lookup(sock->sk); 178 if (!req) { 179 err = -EBUSY; 180 fput(sock->file); 181 goto out_status; 182 } 183 184 trace_handshake_cmd_done(net, req, sock->sk, fd); 185 186 status = -EIO; 187 if (info->attrs[HANDSHAKE_A_DONE_STATUS]) 188 status = nla_get_u32(info->attrs[HANDSHAKE_A_DONE_STATUS]); 189 190 handshake_complete(req, status, info); 191 fput(sock->file); 192 return 0; 193 194 out_status: 195 trace_handshake_cmd_done_err(net, req, sock->sk, err); 196 return err; 197 } 198 199 static unsigned int handshake_net_id; 200 201 static int __net_init handshake_net_init(struct net *net) 202 { 203 struct handshake_net *hn = net_generic(net, handshake_net_id); 204 unsigned long tmp; 205 struct sysinfo si; 206 207 /* 208 * Arbitrary limit to prevent handshakes that do not make 209 * progress from clogging up the system. The cap scales up 210 * with the amount of physical memory on the system. 211 */ 212 si_meminfo(&si); 213 tmp = si.totalram / (25 * si.mem_unit); 214 hn->hn_pending_max = clamp(tmp, 3UL, 50UL); 215 216 spin_lock_init(&hn->hn_lock); 217 hn->hn_pending = 0; 218 hn->hn_flags = 0; 219 INIT_LIST_HEAD(&hn->hn_requests); 220 return 0; 221 } 222 223 static void __net_exit handshake_net_exit(struct net *net) 224 { 225 struct handshake_net *hn = net_generic(net, handshake_net_id); 226 struct handshake_req *req; 227 LIST_HEAD(requests); 228 229 /* 230 * Drain the net's pending list. Requests that have been 231 * accepted and are in progress will be destroyed when 232 * the socket is closed. 233 */ 234 spin_lock(&hn->hn_lock); 235 set_bit(HANDSHAKE_F_NET_DRAINING, &hn->hn_flags); 236 list_splice_init(&requests, &hn->hn_requests); 237 spin_unlock(&hn->hn_lock); 238 239 while (!list_empty(&requests)) { 240 req = list_first_entry(&requests, struct handshake_req, hr_list); 241 list_del(&req->hr_list); 242 243 /* 244 * Requests on this list have not yet been 245 * accepted, so they do not have an fd to put. 246 */ 247 248 handshake_complete(req, -ETIMEDOUT, NULL); 249 } 250 } 251 252 static struct pernet_operations handshake_genl_net_ops = { 253 .init = handshake_net_init, 254 .exit = handshake_net_exit, 255 .id = &handshake_net_id, 256 .size = sizeof(struct handshake_net), 257 }; 258 259 /** 260 * handshake_pernet - Get the handshake private per-net structure 261 * @net: network namespace 262 * 263 * Returns a pointer to the net's private per-net structure for the 264 * handshake module, or NULL if handshake_init() failed. 265 */ 266 struct handshake_net *handshake_pernet(struct net *net) 267 { 268 return handshake_net_id ? 269 net_generic(net, handshake_net_id) : NULL; 270 } 271 EXPORT_SYMBOL_IF_KUNIT(handshake_pernet); 272 273 static int __init handshake_init(void) 274 { 275 int ret; 276 277 ret = handshake_req_hash_init(); 278 if (ret) { 279 pr_warn("handshake: hash initialization failed (%d)\n", ret); 280 return ret; 281 } 282 283 ret = genl_register_family(&handshake_nl_family); 284 if (ret) { 285 pr_warn("handshake: netlink registration failed (%d)\n", ret); 286 handshake_req_hash_destroy(); 287 return ret; 288 } 289 290 /* 291 * ORDER: register_pernet_subsys must be done last. 292 * 293 * If initialization does not make it past pernet_subsys 294 * registration, then handshake_net_id will remain 0. That 295 * shunts the handshake consumer API to return ENOTSUPP 296 * to prevent it from dereferencing something that hasn't 297 * been allocated. 298 */ 299 ret = register_pernet_subsys(&handshake_genl_net_ops); 300 if (ret) { 301 pr_warn("handshake: pernet registration failed (%d)\n", ret); 302 genl_unregister_family(&handshake_nl_family); 303 handshake_req_hash_destroy(); 304 } 305 306 return ret; 307 } 308 309 static void __exit handshake_exit(void) 310 { 311 unregister_pernet_subsys(&handshake_genl_net_ops); 312 handshake_net_id = 0; 313 314 handshake_req_hash_destroy(); 315 genl_unregister_family(&handshake_nl_family); 316 } 317 318 module_init(handshake_init); 319 module_exit(handshake_exit); 320