net/sunrpc/auth_generic.c

   1 /*
   2  * Generic RPC credential
   3  *
   4  * Copyright (C) 2008, Trond Myklebust <Trond.Myklebust@netapp.com>
   5  */
   6
   7 #include <linux/err.h>
   8 #include <linux/slab.h>
   9 #include <linux/types.h>
  10 #include <linux/module.h>
  11 #include <linux/sched.h>
  12 #include <linux/sunrpc/auth.h>
  13 #include <linux/sunrpc/clnt.h>
  14 #include <linux/sunrpc/debug.h>
  15 #include <linux/sunrpc/sched.h>
  16
  17 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
  18 # define RPCDBG_FACILITY        RPCDBG_AUTH
  19 #endif
  20
  21 #define RPC_MACHINE_CRED_USERID         GLOBAL_ROOT_UID
  22 #define RPC_MACHINE_CRED_GROUPID        GLOBAL_ROOT_GID
  23
  24 struct generic_cred {
  25         struct rpc_cred gc_base;
  26         struct auth_cred acred;
  27 };
  28
  29 static struct rpc_auth generic_auth;
  30 static const struct rpc_credops generic_credops;
  31
  32 /*
  33  * Public call interface
  34  */
  35 struct rpc_cred *rpc_lookup_cred(void)
  36 {
  37         return rpcauth_lookupcred(&generic_auth, 0);
  38 }
  39 EXPORT_SYMBOL_GPL(rpc_lookup_cred);
  40
  41 struct rpc_cred *rpc_lookup_cred_nonblock(void)
  42 {
  43         return rpcauth_lookupcred(&generic_auth, RPCAUTH_LOOKUP_RCU);
  44 }
  45 EXPORT_SYMBOL_GPL(rpc_lookup_cred_nonblock);
  46
  47 /*
  48  * Public call interface for looking up machine creds.
  49  */
  50 struct rpc_cred *rpc_lookup_machine_cred(const char *service_name)
  51 {
  52         struct auth_cred acred = {
  53                 .uid = RPC_MACHINE_CRED_USERID,
  54                 .gid = RPC_MACHINE_CRED_GROUPID,
  55                 .principal = service_name,
  56                 .machine_cred = 1,
  57         };
  58
  59         dprintk("RPC:       looking up machine cred for service %s\n",
  60                         service_name);
  61         return generic_auth.au_ops->lookup_cred(&generic_auth, &acred, 0);
  62 }
  63 EXPORT_SYMBOL_GPL(rpc_lookup_machine_cred);
  64
  65 static struct rpc_cred *generic_bind_cred(struct rpc_task *task,
  66                 struct rpc_cred *cred, int lookupflags)
  67 {
  68         struct rpc_auth *auth = task->tk_client->cl_auth;
  69         struct auth_cred *acred = &container_of(cred, struct generic_cred, gc_base)->acred;
  70
  71         return auth->au_ops->lookup_cred(auth, acred, lookupflags);
  72 }
  73
  74 /*
  75  * Lookup generic creds for current process
  76  */
  77 static struct rpc_cred *
  78 generic_lookup_cred(struct rpc_auth *auth, struct auth_cred *acred, int flags)
  79 {
  80         return rpcauth_lookup_credcache(&generic_auth, acred, flags);
  81 }
  82
  83 static struct rpc_cred *
  84 generic_create_cred(struct rpc_auth *auth, struct auth_cred *acred, int flags)
  85 {
  86         struct generic_cred *gcred;
  87
  88         gcred = kmalloc(sizeof(*gcred), GFP_KERNEL);
  89         if (gcred == NULL)
  90                 return ERR_PTR(-ENOMEM);
  91
  92         rpcauth_init_cred(&gcred->gc_base, acred, &generic_auth, &generic_credops);
  93         gcred->gc_base.cr_flags = 1UL << RPCAUTH_CRED_UPTODATE;
  94
  95         gcred->acred.uid = acred->uid;
  96         gcred->acred.gid = acred->gid;
  97         gcred->acred.group_info = acred->group_info;
  98         gcred->acred.ac_flags = 0;
  99         if (gcred->acred.group_info != NULL)
 100                 get_group_info(gcred->acred.group_info);
 101         gcred->acred.machine_cred = acred->machine_cred;
 102         gcred->acred.principal = acred->principal;
 103
 104         dprintk("RPC:       allocated %s cred %p for uid %d gid %d\n",
 105                         gcred->acred.machine_cred ? "machine" : "generic",
 106                         gcred,
 107                         from_kuid(&init_user_ns, acred->uid),
 108                         from_kgid(&init_user_ns, acred->gid));
 109         return &gcred->gc_base;
 110 }
 111
 112 static void
 113 generic_free_cred(struct rpc_cred *cred)
 114 {
 115         struct generic_cred *gcred = container_of(cred, struct generic_cred, gc_base);
 116
 117         dprintk("RPC:       generic_free_cred %p\n", gcred);
 118         if (gcred->acred.group_info != NULL)
 119                 put_group_info(gcred->acred.group_info);
 120         kfree(gcred);
 121 }
 122
 123 static void
 124 generic_free_cred_callback(struct rcu_head *head)
 125 {
 126         struct rpc_cred *cred = container_of(head, struct rpc_cred, cr_rcu);
 127         generic_free_cred(cred);
 128 }
 129
 130 static void
 131 generic_destroy_cred(struct rpc_cred *cred)
 132 {
 133         call_rcu(&cred->cr_rcu, generic_free_cred_callback);
 134 }
 135
 136 static int
 137 machine_cred_match(struct auth_cred *acred, struct generic_cred *gcred, int flags)
 138 {
 139         if (!gcred->acred.machine_cred ||
 140             gcred->acred.principal != acred->principal ||
 141             !uid_eq(gcred->acred.uid, acred->uid) ||
 142             !gid_eq(gcred->acred.gid, acred->gid))
 143                 return 0;
 144         return 1;
 145 }
 146
 147 /*
 148  * Match credentials against current process creds.
 149  */
 150 static int
 151 generic_match(struct auth_cred *acred, struct rpc_cred *cred, int flags)
 152 {
 153         struct generic_cred *gcred = container_of(cred, struct generic_cred, gc_base);
 154         int i;
 155
 156         if (acred->machine_cred)
 157                 return machine_cred_match(acred, gcred, flags);
 158
 159         if (!uid_eq(gcred->acred.uid, acred->uid) ||
 160             !gid_eq(gcred->acred.gid, acred->gid) ||
 161             gcred->acred.machine_cred != 0)
 162                 goto out_nomatch;
 163
 164         /* Optimisation in the case where pointers are identical... */
 165         if (gcred->acred.group_info == acred->group_info)
 166                 goto out_match;
 167
 168         /* Slow path... */
 169         if (gcred->acred.group_info->ngroups != acred->group_info->ngroups)
 170                 goto out_nomatch;
 171         for (i = 0; i < gcred->acred.group_info->ngroups; i++) {
 172                 if (!gid_eq(GROUP_AT(gcred->acred.group_info, i),
 173                                 GROUP_AT(acred->group_info, i)))
 174                         goto out_nomatch;
 175         }
 176 out_match:
 177         return 1;
 178 out_nomatch:
 179         return 0;
 180 }
 181
 182 int __init rpc_init_generic_auth(void)
 183 {
 184         return rpcauth_init_credcache(&generic_auth);
 185 }
 186
 187 void rpc_destroy_generic_auth(void)
 188 {
 189         rpcauth_destroy_credcache(&generic_auth);
 190 }
 191
 192 /*
 193  * Test the the current time (now) against the underlying credential key expiry
 194  * minus a timeout and setup notification.
 195  *
 196  * The normal case:
 197  * If 'now' is before the key expiry minus RPC_KEY_EXPIRE_TIMEO, set
 198  * the RPC_CRED_NOTIFY_TIMEOUT flag to setup the underlying credential
 199  * rpc_credops crmatch routine to notify this generic cred when it's key
 200  * expiration is within RPC_KEY_EXPIRE_TIMEO, and return 0.
 201  *
 202  * The error case:
 203  * If the underlying cred lookup fails, return -EACCES.
 204  *
 205  * The 'almost' error case:
 206  * If 'now' is within key expiry minus RPC_KEY_EXPIRE_TIMEO, but not within
 207  * key expiry minus RPC_KEY_EXPIRE_FAIL, set the RPC_CRED_EXPIRE_SOON bit
 208  * on the acred ac_flags and return 0.
 209  */
 210 static int
 211 generic_key_timeout(struct rpc_auth *auth, struct rpc_cred *cred)
 212 {
 213         struct auth_cred *acred = &container_of(cred, struct generic_cred,
 214                                                 gc_base)->acred;
 215         struct rpc_cred *tcred;
 216         int ret = 0;
 217
 218
 219         /* Fast track for non crkey_timeout (no key) underlying credentials */
 220         if (test_bit(RPC_CRED_NO_CRKEY_TIMEOUT, &acred->ac_flags))
 221                 return 0;
 222
 223         /* Fast track for the normal case */
 224         if (test_bit(RPC_CRED_NOTIFY_TIMEOUT, &acred->ac_flags))
 225                 return 0;
 226
 227         /* lookup_cred either returns a valid referenced rpc_cred, or PTR_ERR */
 228         tcred = auth->au_ops->lookup_cred(auth, acred, 0);
 229         if (IS_ERR(tcred))
 230                 return -EACCES;
 231
 232         if (!tcred->cr_ops->crkey_timeout) {
 233                 set_bit(RPC_CRED_NO_CRKEY_TIMEOUT, &acred->ac_flags);
 234                 ret = 0;
 235                 goto out_put;
 236         }
 237
 238         /* Test for the almost error case */
 239         ret = tcred->cr_ops->crkey_timeout(tcred);
 240         if (ret != 0) {
 241                 set_bit(RPC_CRED_KEY_EXPIRE_SOON, &acred->ac_flags);
 242                 ret = 0;
 243         } else {
 244                 /* In case underlying cred key has been reset */
 245                 if (test_and_clear_bit(RPC_CRED_KEY_EXPIRE_SOON,
 246                                         &acred->ac_flags))
 247                         dprintk("RPC:        UID %d Credential key reset\n",
 248                                 from_kuid(&init_user_ns, tcred->cr_uid));
 249                 /* set up fasttrack for the normal case */
 250                 set_bit(RPC_CRED_NOTIFY_TIMEOUT, &acred->ac_flags);
 251         }
 252
 253 out_put:
 254         put_rpccred(tcred);
 255         return ret;
 256 }
 257
 258 static const struct rpc_authops generic_auth_ops = {
 259         .owner = THIS_MODULE,
 260         .au_name = "Generic",
 261         .lookup_cred = generic_lookup_cred,
 262         .crcreate = generic_create_cred,
 263         .key_timeout = generic_key_timeout,
 264 };
 265
 266 static struct rpc_auth generic_auth = {
 267         .au_ops = &generic_auth_ops,
 268         .au_count = ATOMIC_INIT(0),
 269 };
 270
 271 static bool generic_key_to_expire(struct rpc_cred *cred)
 272 {
 273         struct auth_cred *acred = &container_of(cred, struct generic_cred,
 274                                                 gc_base)->acred;
 275         bool ret;
 276
 277         get_rpccred(cred);
 278         ret = test_bit(RPC_CRED_KEY_EXPIRE_SOON, &acred->ac_flags);
 279         put_rpccred(cred);
 280
 281         return ret;
 282 }
 283
 284 static const struct rpc_credops generic_credops = {
 285         .cr_name = "Generic cred",
 286         .crdestroy = generic_destroy_cred,
 287         .crbind = generic_bind_cred,
 288         .crmatch = generic_match,
 289         .crkey_to_expire = generic_key_to_expire,
 290 };