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 int handshake_nl_accept_doit(struct sk_buff *skb, struct genl_info *info) 91 { 92 struct net *net = sock_net(skb->sk); 93 struct handshake_net *hn = handshake_pernet(net); 94 struct handshake_req *req = NULL; 95 struct socket *sock; 96 int class, fd, err; 97 98 err = -EOPNOTSUPP; 99 if (!hn) 100 goto out_status; 101 102 err = -EINVAL; 103 if (GENL_REQ_ATTR_CHECK(info, HANDSHAKE_A_ACCEPT_HANDLER_CLASS)) 104 goto out_status; 105 class = nla_get_u32(info->attrs[HANDSHAKE_A_ACCEPT_HANDLER_CLASS]); 106 107 err = -EAGAIN; 108 req = handshake_req_next(hn, class); 109 if (!req) 110 goto out_status; 111 112 sock = req->hr_sk->sk_socket; 113 fd = get_unused_fd_flags(O_CLOEXEC); 114 if (fd < 0) { 115 err = fd; 116 goto out_complete; 117 } 118 119 err = req->hr_proto->hp_accept(req, info, fd); 120 if (err) { 121 put_unused_fd(fd); 122 goto out_complete; 123 } 124 125 fd_install(fd, get_file(sock->file)); 126 127 trace_handshake_cmd_accept(net, req, req->hr_sk, fd); 128 return 0; 129 130 out_complete: 131 handshake_complete(req, -EIO, NULL); 132 out_status: 133 trace_handshake_cmd_accept_err(net, req, NULL, err); 134 return err; 135 } 136 137 int handshake_nl_done_doit(struct sk_buff *skb, struct genl_info *info) 138 { 139 struct net *net = sock_net(skb->sk); 140 struct handshake_req *req; 141 struct socket *sock; 142 int fd, status, err; 143 144 if (GENL_REQ_ATTR_CHECK(info, HANDSHAKE_A_DONE_SOCKFD)) 145 return -EINVAL; 146 fd = nla_get_s32(info->attrs[HANDSHAKE_A_DONE_SOCKFD]); 147 148 sock = sockfd_lookup(fd, &err); 149 if (!sock) 150 return err; 151 152 req = handshake_req_hash_lookup(sock->sk); 153 if (!req) { 154 err = -EBUSY; 155 trace_handshake_cmd_done_err(net, req, sock->sk, err); 156 sockfd_put(sock); 157 return err; 158 } 159 160 trace_handshake_cmd_done(net, req, sock->sk, fd); 161 162 status = -EIO; 163 if (info->attrs[HANDSHAKE_A_DONE_STATUS]) 164 status = nla_get_u32(info->attrs[HANDSHAKE_A_DONE_STATUS]); 165 166 handshake_complete(req, status, info); 167 sockfd_put(sock); 168 return 0; 169 } 170 171 static unsigned int handshake_net_id; 172 173 static int __net_init handshake_net_init(struct net *net) 174 { 175 struct handshake_net *hn = net_generic(net, handshake_net_id); 176 unsigned long tmp; 177 struct sysinfo si; 178 179 /* 180 * Arbitrary limit to prevent handshakes that do not make 181 * progress from clogging up the system. The cap scales up 182 * with the amount of physical memory on the system. 183 */ 184 si_meminfo(&si); 185 tmp = si.totalram / (25 * si.mem_unit); 186 hn->hn_pending_max = clamp(tmp, 3UL, 50UL); 187 188 spin_lock_init(&hn->hn_lock); 189 hn->hn_pending = 0; 190 hn->hn_flags = 0; 191 INIT_LIST_HEAD(&hn->hn_requests); 192 return 0; 193 } 194 195 static void __net_exit handshake_net_exit(struct net *net) 196 { 197 struct handshake_net *hn = net_generic(net, handshake_net_id); 198 struct handshake_req *req; 199 LIST_HEAD(requests); 200 201 /* 202 * Drain the net's pending list. Requests that have been 203 * accepted and are in progress will be destroyed when 204 * the socket is closed. 205 */ 206 spin_lock(&hn->hn_lock); 207 set_bit(HANDSHAKE_F_NET_DRAINING, &hn->hn_flags); 208 list_splice_init(&requests, &hn->hn_requests); 209 spin_unlock(&hn->hn_lock); 210 211 while (!list_empty(&requests)) { 212 req = list_first_entry(&requests, struct handshake_req, hr_list); 213 list_del(&req->hr_list); 214 215 /* 216 * Requests on this list have not yet been 217 * accepted, so they do not have an fd to put. 218 */ 219 220 handshake_complete(req, -ETIMEDOUT, NULL); 221 } 222 } 223 224 static struct pernet_operations handshake_genl_net_ops = { 225 .init = handshake_net_init, 226 .exit = handshake_net_exit, 227 .id = &handshake_net_id, 228 .size = sizeof(struct handshake_net), 229 }; 230 231 /** 232 * handshake_pernet - Get the handshake private per-net structure 233 * @net: network namespace 234 * 235 * Returns a pointer to the net's private per-net structure for the 236 * handshake module, or NULL if handshake_init() failed. 237 */ 238 struct handshake_net *handshake_pernet(struct net *net) 239 { 240 return handshake_net_id ? 241 net_generic(net, handshake_net_id) : NULL; 242 } 243 EXPORT_SYMBOL_IF_KUNIT(handshake_pernet); 244 245 static int __init handshake_init(void) 246 { 247 int ret; 248 249 ret = handshake_req_hash_init(); 250 if (ret) { 251 pr_warn("handshake: hash initialization failed (%d)\n", ret); 252 return ret; 253 } 254 255 ret = genl_register_family(&handshake_nl_family); 256 if (ret) { 257 pr_warn("handshake: netlink registration failed (%d)\n", ret); 258 handshake_req_hash_destroy(); 259 return ret; 260 } 261 262 /* 263 * ORDER: register_pernet_subsys must be done last. 264 * 265 * If initialization does not make it past pernet_subsys 266 * registration, then handshake_net_id will remain 0. That 267 * shunts the handshake consumer API to return ENOTSUPP 268 * to prevent it from dereferencing something that hasn't 269 * been allocated. 270 */ 271 ret = register_pernet_subsys(&handshake_genl_net_ops); 272 if (ret) { 273 pr_warn("handshake: pernet registration failed (%d)\n", ret); 274 genl_unregister_family(&handshake_nl_family); 275 handshake_req_hash_destroy(); 276 } 277 278 return ret; 279 } 280 281 static void __exit handshake_exit(void) 282 { 283 unregister_pernet_subsys(&handshake_genl_net_ops); 284 handshake_net_id = 0; 285 286 handshake_req_hash_destroy(); 287 genl_unregister_family(&handshake_nl_family); 288 } 289 290 module_init(handshake_init); 291 module_exit(handshake_exit); 292