net/sunrpc/svcauth.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * linux/net/sunrpc/svcauth.c
   4  *
   5  * The generic interface for RPC authentication on the server side.
   6  *
   7  * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
   8  *
   9  * CHANGES
  10  * 19-Apr-2000 Chris Evans      - Security fix
  11  */
  12
  13 #include <linux/types.h>
  14 #include <linux/module.h>
  15 #include <linux/sunrpc/types.h>
  16 #include <linux/sunrpc/xdr.h>
  17 #include <linux/sunrpc/svcsock.h>
  18 #include <linux/sunrpc/svcauth.h>
  19 #include <linux/err.h>
  20 #include <linux/hash.h>
  21 #include <linux/user_namespace.h>
  22
  23 #include <trace/events/sunrpc.h>
  24
  25 #include "sunrpc.h"
  26
  27 #define RPCDBG_FACILITY RPCDBG_AUTH
  28
  29
  30 /*
  31  * Table of authenticators
  32  */
  33 extern struct auth_ops svcauth_null;
  34 extern struct auth_ops svcauth_unix;
  35 extern struct auth_ops svcauth_tls;
  36
  37 static struct auth_ops __rcu *authtab[RPC_AUTH_MAXFLAVOR] = {
  38         [RPC_AUTH_NULL] = (struct auth_ops __force __rcu *)&svcauth_null,
  39         [RPC_AUTH_UNIX] = (struct auth_ops __force __rcu *)&svcauth_unix,
  40         [RPC_AUTH_TLS]  = (struct auth_ops __force __rcu *)&svcauth_tls,
  41 };
  42
  43 static struct auth_ops *
  44 svc_get_auth_ops(rpc_authflavor_t flavor)
  45 {
  46         struct auth_ops         *aops;
  47
  48         if (flavor >= RPC_AUTH_MAXFLAVOR)
  49                 return NULL;
  50         rcu_read_lock();
  51         aops = rcu_dereference(authtab[flavor]);
  52         if (aops != NULL && !try_module_get(aops->owner))
  53                 aops = NULL;
  54         rcu_read_unlock();
  55         return aops;
  56 }
  57
  58 static void
  59 svc_put_auth_ops(struct auth_ops *aops)
  60 {
  61         module_put(aops->owner);
  62 }
  63
  64 /**
  65  * svc_authenticate - Initialize an outgoing credential
  66  * @rqstp: RPC execution context
  67  *
  68  * Return values:
  69  *   %SVC_OK: XDR encoding of the result can begin
  70  *   %SVC_DENIED: Credential or verifier is not valid
  71  *   %SVC_GARBAGE: Failed to decode credential or verifier
  72  *   %SVC_COMPLETE: GSS context lifetime event; no further action
  73  *   %SVC_DROP: Drop this request; no further action
  74  *   %SVC_CLOSE: Like drop, but also close transport connection
  75  */
  76 enum svc_auth_status svc_authenticate(struct svc_rqst *rqstp)
  77 {
  78         struct auth_ops *aops;
  79         u32 flavor;
  80
  81         rqstp->rq_auth_stat = rpc_auth_ok;
  82
  83         /*
  84          * Decode the Call credential's flavor field. The credential's
  85          * body field is decoded in the chosen ->accept method below.
  86          */
  87         if (xdr_stream_decode_u32(&rqstp->rq_arg_stream, &flavor) < 0)
  88                 return SVC_GARBAGE;
  89
  90         aops = svc_get_auth_ops(flavor);
  91         if (aops == NULL) {
  92                 rqstp->rq_auth_stat = rpc_autherr_badcred;
  93                 return SVC_DENIED;
  94         }
  95
  96         rqstp->rq_auth_slack = 0;
  97         init_svc_cred(&rqstp->rq_cred);
  98
  99         rqstp->rq_authop = aops;
 100         return aops->accept(rqstp);
 101 }
 102
 103 /**
 104  * svc_set_client - Assign an appropriate 'auth_domain' as the client
 105  * @rqstp: RPC execution context
 106  *
 107  * Return values:
 108  *   %SVC_OK: Client was found and assigned
 109  *   %SVC_DENY: Client was explicitly denied
 110  *   %SVC_DROP: Ignore this request
 111  *   %SVC_CLOSE: Ignore this request and close the connection
 112  */
 113 enum svc_auth_status svc_set_client(struct svc_rqst *rqstp)
 114 {
 115         rqstp->rq_client = NULL;
 116         return rqstp->rq_authop->set_client(rqstp);
 117 }
 118 EXPORT_SYMBOL_GPL(svc_set_client);
 119
 120 /**
 121  * svc_authorise - Finalize credentials/verifier and release resources
 122  * @rqstp: RPC execution context
 123  *
 124  * Returns zero on success, or a negative errno.
 125  */
 126 int svc_authorise(struct svc_rqst *rqstp)
 127 {
 128         struct auth_ops *aops = rqstp->rq_authop;
 129         int rv = 0;
 130
 131         rqstp->rq_authop = NULL;
 132
 133         if (aops) {
 134                 rv = aops->release(rqstp);
 135                 svc_put_auth_ops(aops);
 136         }
 137         return rv;
 138 }
 139
 140 int
 141 svc_auth_register(rpc_authflavor_t flavor, struct auth_ops *aops)
 142 {
 143         struct auth_ops *old;
 144         int rv = -EINVAL;
 145
 146         if (flavor < RPC_AUTH_MAXFLAVOR) {
 147                 old = cmpxchg((struct auth_ops ** __force)&authtab[flavor], NULL, aops);
 148                 if (old == NULL || old == aops)
 149                         rv = 0;
 150         }
 151         return rv;
 152 }
 153 EXPORT_SYMBOL_GPL(svc_auth_register);
 154
 155 void
 156 svc_auth_unregister(rpc_authflavor_t flavor)
 157 {
 158         if (flavor < RPC_AUTH_MAXFLAVOR)
 159                 rcu_assign_pointer(authtab[flavor], NULL);
 160 }
 161 EXPORT_SYMBOL_GPL(svc_auth_unregister);
 162
 163 /**
 164  * svc_auth_flavor - return RPC transaction's RPC_AUTH flavor
 165  * @rqstp: RPC transaction context
 166  *
 167  * Returns an RPC flavor or GSS pseudoflavor.
 168  */
 169 rpc_authflavor_t svc_auth_flavor(struct svc_rqst *rqstp)
 170 {
 171         struct auth_ops *aops = rqstp->rq_authop;
 172
 173         if (!aops->pseudoflavor)
 174                 return aops->flavour;
 175         return aops->pseudoflavor(rqstp);
 176 }
 177 EXPORT_SYMBOL_GPL(svc_auth_flavor);
 178
 179 /**
 180  * svcauth_map_clnt_to_svc_cred_local - maps a generic cred
 181  * to a svc_cred suitable for use in nfsd.
 182  * @clnt: rpc_clnt associated with nfs client
 183  * @cred: generic cred associated with nfs client
 184  * @svc: returned svc_cred that is suitable for use in nfsd
 185  */
 186 void svcauth_map_clnt_to_svc_cred_local(struct rpc_clnt *clnt,
 187                                         const struct cred *cred,
 188                                         struct svc_cred *svc)
 189 {
 190         struct user_namespace *userns = clnt->cl_cred ?
 191                 clnt->cl_cred->user_ns : &init_user_ns;
 192
 193         memset(svc, 0, sizeof(struct svc_cred));
 194
 195         svc->cr_uid = KUIDT_INIT(from_kuid_munged(userns, cred->fsuid));
 196         svc->cr_gid = KGIDT_INIT(from_kgid_munged(userns, cred->fsgid));
 197         svc->cr_flavor = clnt->cl_auth->au_flavor;
 198         if (cred->group_info)
 199                 svc->cr_group_info = get_group_info(cred->group_info);
 200         /* These aren't relevant for local (network is bypassed) */
 201         svc->cr_principal = NULL;
 202         svc->cr_gss_mech = NULL;
 203 }
 204 EXPORT_SYMBOL_GPL(svcauth_map_clnt_to_svc_cred_local);
 205
 206 /**************************************************
 207  * 'auth_domains' are stored in a hash table indexed by name.
 208  * When the last reference to an 'auth_domain' is dropped,
 209  * the object is unhashed and freed.
 210  * If auth_domain_lookup fails to find an entry, it will return
 211  * it's second argument 'new'.  If this is non-null, it will
 212  * have been atomically linked into the table.
 213  */
 214
 215 #define DN_HASHBITS     6
 216 #define DN_HASHMAX      (1<<DN_HASHBITS)
 217
 218 static struct hlist_head        auth_domain_table[DN_HASHMAX];
 219 static DEFINE_SPINLOCK(auth_domain_lock);
 220
 221 static void auth_domain_release(struct kref *kref)
 222         __releases(&auth_domain_lock)
 223 {
 224         struct auth_domain *dom = container_of(kref, struct auth_domain, ref);
 225
 226         hlist_del_rcu(&dom->hash);
 227         dom->flavour->domain_release(dom);
 228         spin_unlock(&auth_domain_lock);
 229 }
 230
 231 void auth_domain_put(struct auth_domain *dom)
 232 {
 233         kref_put_lock(&dom->ref, auth_domain_release, &auth_domain_lock);
 234 }
 235 EXPORT_SYMBOL_GPL(auth_domain_put);
 236
 237 struct auth_domain *
 238 auth_domain_lookup(char *name, struct auth_domain *new)
 239 {
 240         struct auth_domain *hp;
 241         struct hlist_head *head;
 242
 243         head = &auth_domain_table[hash_str(name, DN_HASHBITS)];
 244
 245         spin_lock(&auth_domain_lock);
 246
 247         hlist_for_each_entry(hp, head, hash) {
 248                 if (strcmp(hp->name, name)==0) {
 249                         kref_get(&hp->ref);
 250                         spin_unlock(&auth_domain_lock);
 251                         return hp;
 252                 }
 253         }
 254         if (new)
 255                 hlist_add_head_rcu(&new->hash, head);
 256         spin_unlock(&auth_domain_lock);
 257         return new;
 258 }
 259 EXPORT_SYMBOL_GPL(auth_domain_lookup);
 260
 261 struct auth_domain *auth_domain_find(char *name)
 262 {
 263         struct auth_domain *hp;
 264         struct hlist_head *head;
 265
 266         head = &auth_domain_table[hash_str(name, DN_HASHBITS)];
 267
 268         rcu_read_lock();
 269         hlist_for_each_entry_rcu(hp, head, hash) {
 270                 if (strcmp(hp->name, name)==0) {
 271                         if (!kref_get_unless_zero(&hp->ref))
 272                                 hp = NULL;
 273                         rcu_read_unlock();
 274                         return hp;
 275                 }
 276         }
 277         rcu_read_unlock();
 278         return NULL;
 279 }
 280 EXPORT_SYMBOL_GPL(auth_domain_find);
 281
 282 /**
 283  * auth_domain_cleanup - check that the auth_domain table is empty
 284  *
 285  * On module unload the auth_domain_table must be empty.  To make it
 286  * easier to catch bugs which don't clean up domains properly, we
 287  * warn if anything remains in the table at cleanup time.
 288  *
 289  * Note that we cannot proactively remove the domains at this stage.
 290  * The ->release() function might be in a module that has already been
 291  * unloaded.
 292  */
 293
 294 void auth_domain_cleanup(void)
 295 {
 296         int h;
 297         struct auth_domain *hp;
 298
 299         for (h = 0; h < DN_HASHMAX; h++)
 300                 hlist_for_each_entry(hp, &auth_domain_table[h], hash)
 301                         pr_warn("svc: domain %s still present at module unload.\n",
 302                                 hp->name);
 303 }