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