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