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