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