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; 161 struct socket *sock; 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 sock = sockfd_lookup(fd, &err); 169 if (!sock) 170 return err; 171 172 req = handshake_req_hash_lookup(sock->sk); 173 if (!req) { 174 err = -EBUSY; 175 trace_handshake_cmd_done_err(net, req, sock->sk, err); 176 fput(sock->file); 177 return err; 178 } 179 180 trace_handshake_cmd_done(net, req, sock->sk, fd); 181 182 status = -EIO; 183 if (info->attrs[HANDSHAKE_A_DONE_STATUS]) 184 status = nla_get_u32(info->attrs[HANDSHAKE_A_DONE_STATUS]); 185 186 handshake_complete(req, status, info); 187 fput(sock->file); 188 return 0; 189 } 190 191 static unsigned int handshake_net_id; 192 193 static int __net_init handshake_net_init(struct net *net) 194 { 195 struct handshake_net *hn = net_generic(net, handshake_net_id); 196 unsigned long tmp; 197 struct sysinfo si; 198 199 /* 200 * Arbitrary limit to prevent handshakes that do not make 201 * progress from clogging up the system. The cap scales up 202 * with the amount of physical memory on the system. 203 */ 204 si_meminfo(&si); 205 tmp = si.totalram / (25 * si.mem_unit); 206 hn->hn_pending_max = clamp(tmp, 3UL, 50UL); 207 208 spin_lock_init(&hn->hn_lock); 209 hn->hn_pending = 0; 210 hn->hn_flags = 0; 211 INIT_LIST_HEAD(&hn->hn_requests); 212 return 0; 213 } 214 215 static void __net_exit handshake_net_exit(struct net *net) 216 { 217 struct handshake_net *hn = net_generic(net, handshake_net_id); 218 struct handshake_req *req; 219 LIST_HEAD(requests); 220 221 /* 222 * Drain the net's pending list. Requests that have been 223 * accepted and are in progress will be destroyed when 224 * the socket is closed. 225 */ 226 spin_lock(&hn->hn_lock); 227 set_bit(HANDSHAKE_F_NET_DRAINING, &hn->hn_flags); 228 list_splice_init(&requests, &hn->hn_requests); 229 spin_unlock(&hn->hn_lock); 230 231 while (!list_empty(&requests)) { 232 req = list_first_entry(&requests, struct handshake_req, hr_list); 233 list_del(&req->hr_list); 234 235 /* 236 * Requests on this list have not yet been 237 * accepted, so they do not have an fd to put. 238 */ 239 240 handshake_complete(req, -ETIMEDOUT, NULL); 241 } 242 } 243 244 static struct pernet_operations handshake_genl_net_ops = { 245 .init = handshake_net_init, 246 .exit = handshake_net_exit, 247 .id = &handshake_net_id, 248 .size = sizeof(struct handshake_net), 249 }; 250 251 /** 252 * handshake_pernet - Get the handshake private per-net structure 253 * @net: network namespace 254 * 255 * Returns a pointer to the net's private per-net structure for the 256 * handshake module, or NULL if handshake_init() failed. 257 */ 258 struct handshake_net *handshake_pernet(struct net *net) 259 { 260 return handshake_net_id ? 261 net_generic(net, handshake_net_id) : NULL; 262 } 263 EXPORT_SYMBOL_IF_KUNIT(handshake_pernet); 264 265 static int __init handshake_init(void) 266 { 267 int ret; 268 269 ret = handshake_req_hash_init(); 270 if (ret) { 271 pr_warn("handshake: hash initialization failed (%d)\n", ret); 272 return ret; 273 } 274 275 ret = genl_register_family(&handshake_nl_family); 276 if (ret) { 277 pr_warn("handshake: netlink registration failed (%d)\n", ret); 278 handshake_req_hash_destroy(); 279 return ret; 280 } 281 282 /* 283 * ORDER: register_pernet_subsys must be done last. 284 * 285 * If initialization does not make it past pernet_subsys 286 * registration, then handshake_net_id will remain 0. That 287 * shunts the handshake consumer API to return ENOTSUPP 288 * to prevent it from dereferencing something that hasn't 289 * been allocated. 290 */ 291 ret = register_pernet_subsys(&handshake_genl_net_ops); 292 if (ret) { 293 pr_warn("handshake: pernet registration failed (%d)\n", ret); 294 genl_unregister_family(&handshake_nl_family); 295 handshake_req_hash_destroy(); 296 } 297 298 return ret; 299 } 300 301 static void __exit handshake_exit(void) 302 { 303 unregister_pernet_subsys(&handshake_genl_net_ops); 304 handshake_net_id = 0; 305 306 handshake_req_hash_destroy(); 307 genl_unregister_family(&handshake_nl_family); 308 } 309 310 module_init(handshake_init); 311 module_exit(handshake_exit); 312