1 /* 2 * linux/fs/nfs/callback.c 3 * 4 * Copyright (C) 2004 Trond Myklebust 5 * 6 * NFSv4 callback handling 7 */ 8 9 #include <linux/completion.h> 10 #include <linux/ip.h> 11 #include <linux/module.h> 12 #include <linux/smp_lock.h> 13 #include <linux/sunrpc/svc.h> 14 #include <linux/sunrpc/svcsock.h> 15 #include <linux/nfs_fs.h> 16 #include <linux/mutex.h> 17 #include <linux/freezer.h> 18 #include <linux/kthread.h> 19 #include <linux/sunrpc/svcauth_gss.h> 20 21 #include <net/inet_sock.h> 22 23 #include "nfs4_fs.h" 24 #include "callback.h" 25 #include "internal.h" 26 27 #define NFSDBG_FACILITY NFSDBG_CALLBACK 28 29 struct nfs_callback_data { 30 unsigned int users; 31 struct svc_rqst *rqst; 32 struct task_struct *task; 33 }; 34 35 static struct nfs_callback_data nfs_callback_info; 36 static DEFINE_MUTEX(nfs_callback_mutex); 37 static struct svc_program nfs4_callback_program; 38 39 unsigned int nfs_callback_set_tcpport; 40 unsigned short nfs_callback_tcpport; 41 static const int nfs_set_port_min = 0; 42 static const int nfs_set_port_max = 65535; 43 44 /* 45 * If the kernel has IPv6 support available, always listen for 46 * both AF_INET and AF_INET6 requests. 47 */ 48 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE) 49 static const sa_family_t nfs_callback_family = AF_INET6; 50 #else 51 static const sa_family_t nfs_callback_family = AF_INET; 52 #endif 53 54 static int param_set_port(const char *val, struct kernel_param *kp) 55 { 56 char *endp; 57 int num = simple_strtol(val, &endp, 0); 58 if (endp == val || *endp || num < nfs_set_port_min || num > nfs_set_port_max) 59 return -EINVAL; 60 *((int *)kp->arg) = num; 61 return 0; 62 } 63 64 module_param_call(callback_tcpport, param_set_port, param_get_int, 65 &nfs_callback_set_tcpport, 0644); 66 67 /* 68 * This is the callback kernel thread. 69 */ 70 static int 71 nfs_callback_svc(void *vrqstp) 72 { 73 int err, preverr = 0; 74 struct svc_rqst *rqstp = vrqstp; 75 76 set_freezable(); 77 78 /* 79 * FIXME: do we really need to run this under the BKL? If so, please 80 * add a comment about what it's intended to protect. 81 */ 82 lock_kernel(); 83 while (!kthread_should_stop()) { 84 /* 85 * Listen for a request on the socket 86 */ 87 err = svc_recv(rqstp, MAX_SCHEDULE_TIMEOUT); 88 if (err == -EAGAIN || err == -EINTR) { 89 preverr = err; 90 continue; 91 } 92 if (err < 0) { 93 if (err != preverr) { 94 printk(KERN_WARNING "%s: unexpected error " 95 "from svc_recv (%d)\n", __func__, err); 96 preverr = err; 97 } 98 schedule_timeout_uninterruptible(HZ); 99 continue; 100 } 101 preverr = err; 102 svc_process(rqstp); 103 } 104 unlock_kernel(); 105 return 0; 106 } 107 108 /* 109 * Bring up the callback thread if it is not already up. 110 */ 111 int nfs_callback_up(void) 112 { 113 struct svc_serv *serv = NULL; 114 int ret = 0; 115 116 mutex_lock(&nfs_callback_mutex); 117 if (nfs_callback_info.users++ || nfs_callback_info.task != NULL) 118 goto out; 119 serv = svc_create(&nfs4_callback_program, NFS4_CALLBACK_BUFSIZE, 120 nfs_callback_family, NULL); 121 ret = -ENOMEM; 122 if (!serv) 123 goto out_err; 124 125 ret = svc_create_xprt(serv, "tcp", nfs_callback_set_tcpport, 126 SVC_SOCK_ANONYMOUS); 127 if (ret <= 0) 128 goto out_err; 129 nfs_callback_tcpport = ret; 130 dprintk("NFS: Callback listener port = %u (af %u)\n", 131 nfs_callback_tcpport, nfs_callback_family); 132 133 nfs_callback_info.rqst = svc_prepare_thread(serv, &serv->sv_pools[0]); 134 if (IS_ERR(nfs_callback_info.rqst)) { 135 ret = PTR_ERR(nfs_callback_info.rqst); 136 nfs_callback_info.rqst = NULL; 137 goto out_err; 138 } 139 140 svc_sock_update_bufs(serv); 141 142 nfs_callback_info.task = kthread_run(nfs_callback_svc, 143 nfs_callback_info.rqst, 144 "nfsv4-svc"); 145 if (IS_ERR(nfs_callback_info.task)) { 146 ret = PTR_ERR(nfs_callback_info.task); 147 svc_exit_thread(nfs_callback_info.rqst); 148 nfs_callback_info.rqst = NULL; 149 nfs_callback_info.task = NULL; 150 goto out_err; 151 } 152 out: 153 /* 154 * svc_create creates the svc_serv with sv_nrthreads == 1, and then 155 * svc_prepare_thread increments that. So we need to call svc_destroy 156 * on both success and failure so that the refcount is 1 when the 157 * thread exits. 158 */ 159 if (serv) 160 svc_destroy(serv); 161 mutex_unlock(&nfs_callback_mutex); 162 return ret; 163 out_err: 164 dprintk("NFS: Couldn't create callback socket or server thread; " 165 "err = %d\n", ret); 166 nfs_callback_info.users--; 167 goto out; 168 } 169 170 /* 171 * Kill the callback thread if it's no longer being used. 172 */ 173 void nfs_callback_down(void) 174 { 175 mutex_lock(&nfs_callback_mutex); 176 nfs_callback_info.users--; 177 if (nfs_callback_info.users == 0 && nfs_callback_info.task != NULL) { 178 kthread_stop(nfs_callback_info.task); 179 svc_exit_thread(nfs_callback_info.rqst); 180 nfs_callback_info.rqst = NULL; 181 nfs_callback_info.task = NULL; 182 } 183 mutex_unlock(&nfs_callback_mutex); 184 } 185 186 static int check_gss_callback_principal(struct nfs_client *clp, 187 struct svc_rqst *rqstp) 188 { 189 struct rpc_clnt *r = clp->cl_rpcclient; 190 char *p = svc_gss_principal(rqstp); 191 192 /* 193 * It might just be a normal user principal, in which case 194 * userspace won't bother to tell us the name at all. 195 */ 196 if (p == NULL) 197 return SVC_DENIED; 198 199 /* Expect a GSS_C_NT_HOSTBASED_NAME like "nfs@serverhostname" */ 200 201 if (memcmp(p, "nfs@", 4) != 0) 202 return SVC_DENIED; 203 p += 4; 204 if (strcmp(p, r->cl_server) != 0) 205 return SVC_DENIED; 206 return SVC_OK; 207 } 208 209 static int nfs_callback_authenticate(struct svc_rqst *rqstp) 210 { 211 struct nfs_client *clp; 212 RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]); 213 int ret = SVC_OK; 214 215 /* Don't talk to strangers */ 216 clp = nfs_find_client(svc_addr(rqstp), 4); 217 if (clp == NULL) 218 return SVC_DROP; 219 220 dprintk("%s: %s NFSv4 callback!\n", __func__, 221 svc_print_addr(rqstp, buf, sizeof(buf))); 222 223 switch (rqstp->rq_authop->flavour) { 224 case RPC_AUTH_NULL: 225 if (rqstp->rq_proc != CB_NULL) 226 ret = SVC_DENIED; 227 break; 228 case RPC_AUTH_UNIX: 229 break; 230 case RPC_AUTH_GSS: 231 ret = check_gss_callback_principal(clp, rqstp); 232 break; 233 default: 234 ret = SVC_DENIED; 235 } 236 nfs_put_client(clp); 237 return ret; 238 } 239 240 /* 241 * Define NFS4 callback program 242 */ 243 static struct svc_version *nfs4_callback_version[] = { 244 [1] = &nfs4_callback_version1, 245 }; 246 247 static struct svc_stat nfs4_callback_stats; 248 249 static struct svc_program nfs4_callback_program = { 250 .pg_prog = NFS4_CALLBACK, /* RPC service number */ 251 .pg_nvers = ARRAY_SIZE(nfs4_callback_version), /* Number of entries */ 252 .pg_vers = nfs4_callback_version, /* version table */ 253 .pg_name = "NFSv4 callback", /* service name */ 254 .pg_class = "nfs", /* authentication class */ 255 .pg_stats = &nfs4_callback_stats, 256 .pg_authenticate = nfs_callback_authenticate, 257 }; 258