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