net/sunrpc/auth_unix.c

   1 /*
   2  * linux/net/sunrpc/auth_unix.c
   3  *
   4  * UNIX-style authentication; no AUTH_SHORT support
   5  *
   6  * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
   7  */
   8
   9 #include <linux/types.h>
  10 #include <linux/sched.h>
  11 #include <linux/module.h>
  12 #include <linux/sunrpc/clnt.h>
  13 #include <linux/sunrpc/auth.h>
  14
  15 #define NFS_NGROUPS     16
  16
  17 struct unx_cred {
  18         struct rpc_cred         uc_base;
  19         gid_t                   uc_gid;
  20         gid_t                   uc_gids[NFS_NGROUPS];
  21 };
  22 #define uc_uid                  uc_base.cr_uid
  23
  24 #define UNX_WRITESLACK          (21 + (UNX_MAXNODENAME >> 2))
  25
  26 #ifdef RPC_DEBUG
  27 # define RPCDBG_FACILITY        RPCDBG_AUTH
  28 #endif
  29
  30 static struct rpc_auth          unix_auth;
  31 static struct rpc_cred_cache    unix_cred_cache;
  32 static const struct rpc_credops unix_credops;
  33
  34 static struct rpc_auth *
  35 unx_create(struct rpc_clnt *clnt, rpc_authflavor_t flavor)
  36 {
  37         dprintk("RPC:       creating UNIX authenticator for client %p\n",
  38                         clnt);
  39         atomic_inc(&unix_auth.au_count);
  40         return &unix_auth;
  41 }
  42
  43 static void
  44 unx_destroy(struct rpc_auth *auth)
  45 {
  46         dprintk("RPC:       destroying UNIX authenticator %p\n", auth);
  47         rpcauth_clear_credcache(auth->au_credcache);
  48 }
  49
  50 /*
  51  * Lookup AUTH_UNIX creds for current process
  52  */
  53 static struct rpc_cred *
  54 unx_lookup_cred(struct rpc_auth *auth, struct auth_cred *acred, int flags)
  55 {
  56         return rpcauth_lookup_credcache(auth, acred, flags);
  57 }
  58
  59 static struct rpc_cred *
  60 unx_create_cred(struct rpc_auth *auth, struct auth_cred *acred, int flags)
  61 {
  62         struct unx_cred *cred;
  63         int             i;
  64
  65         dprintk("RPC:       allocating UNIX cred for uid %d gid %d\n",
  66                         acred->uid, acred->gid);
  67
  68         if (!(cred = kmalloc(sizeof(*cred), GFP_KERNEL)))
  69                 return ERR_PTR(-ENOMEM);
  70
  71         rpcauth_init_cred(&cred->uc_base, acred, auth, &unix_credops);
  72         cred->uc_base.cr_flags = 1UL << RPCAUTH_CRED_UPTODATE;
  73         if (flags & RPCAUTH_LOOKUP_ROOTCREDS) {
  74                 cred->uc_uid = 0;
  75                 cred->uc_gid = 0;
  76                 cred->uc_gids[0] = NOGROUP;
  77         } else {
  78                 int groups = acred->group_info->ngroups;
  79                 if (groups > NFS_NGROUPS)
  80                         groups = NFS_NGROUPS;
  81
  82                 cred->uc_gid = acred->gid;
  83                 for (i = 0; i < groups; i++)
  84                         cred->uc_gids[i] = GROUP_AT(acred->group_info, i);
  85                 if (i < NFS_NGROUPS)
  86                   cred->uc_gids[i] = NOGROUP;
  87         }
  88
  89         return &cred->uc_base;
  90 }
  91
  92 static void
  93 unx_free_cred(struct unx_cred *unx_cred)
  94 {
  95         dprintk("RPC:       unx_free_cred %p\n", unx_cred);
  96         kfree(unx_cred);
  97 }
  98
  99 static void
 100 unx_free_cred_callback(struct rcu_head *head)
 101 {
 102         struct unx_cred *unx_cred = container_of(head, struct unx_cred, uc_base.cr_rcu);
 103         unx_free_cred(unx_cred);
 104 }
 105
 106 static void
 107 unx_destroy_cred(struct rpc_cred *cred)
 108 {
 109         call_rcu(&cred->cr_rcu, unx_free_cred_callback);
 110 }
 111
 112 /*
 113  * Match credentials against current process creds.
 114  * The root_override argument takes care of cases where the caller may
 115  * request root creds (e.g. for NFS swapping).
 116  */
 117 static int
 118 unx_match(struct auth_cred *acred, struct rpc_cred *rcred, int flags)
 119 {
 120         struct unx_cred *cred = container_of(rcred, struct unx_cred, uc_base);
 121         int             i;
 122
 123         if (!(flags & RPCAUTH_LOOKUP_ROOTCREDS)) {
 124                 int groups;
 125
 126                 if (cred->uc_uid != acred->uid
 127                  || cred->uc_gid != acred->gid)
 128                         return 0;
 129
 130                 groups = acred->group_info->ngroups;
 131                 if (groups > NFS_NGROUPS)
 132                         groups = NFS_NGROUPS;
 133                 for (i = 0; i < groups ; i++)
 134                         if (cred->uc_gids[i] != GROUP_AT(acred->group_info, i))
 135                                 return 0;
 136                 return 1;
 137         }
 138         return (cred->uc_uid == 0
 139              && cred->uc_gid == 0
 140              && cred->uc_gids[0] == (gid_t) NOGROUP);
 141 }
 142
 143 /*
 144  * Marshal credentials.
 145  * Maybe we should keep a cached credential for performance reasons.
 146  */
 147 static __be32 *
 148 unx_marshal(struct rpc_task *task, __be32 *p)
 149 {
 150         struct rpc_clnt *clnt = task->tk_client;
 151         struct unx_cred *cred = container_of(task->tk_msg.rpc_cred, struct unx_cred, uc_base);
 152         __be32          *base, *hold;
 153         int             i;
 154
 155         *p++ = htonl(RPC_AUTH_UNIX);
 156         base = p++;
 157         *p++ = htonl(jiffies/HZ);
 158
 159         /*
 160          * Copy the UTS nodename captured when the client was created.
 161          */
 162         p = xdr_encode_array(p, clnt->cl_nodename, clnt->cl_nodelen);
 163
 164         *p++ = htonl((u32) cred->uc_uid);
 165         *p++ = htonl((u32) cred->uc_gid);
 166         hold = p++;
 167         for (i = 0; i < 16 && cred->uc_gids[i] != (gid_t) NOGROUP; i++)
 168                 *p++ = htonl((u32) cred->uc_gids[i]);
 169         *hold = htonl(p - hold - 1);            /* gid array length */
 170         *base = htonl((p - base - 1) << 2);     /* cred length */
 171
 172         *p++ = htonl(RPC_AUTH_NULL);
 173         *p++ = htonl(0);
 174
 175         return p;
 176 }
 177
 178 /*
 179  * Refresh credentials. This is a no-op for AUTH_UNIX
 180  */
 181 static int
 182 unx_refresh(struct rpc_task *task)
 183 {
 184         set_bit(RPCAUTH_CRED_UPTODATE, &task->tk_msg.rpc_cred->cr_flags);
 185         return 0;
 186 }
 187
 188 static __be32 *
 189 unx_validate(struct rpc_task *task, __be32 *p)
 190 {
 191         rpc_authflavor_t        flavor;
 192         u32                     size;
 193
 194         flavor = ntohl(*p++);
 195         if (flavor != RPC_AUTH_NULL &&
 196             flavor != RPC_AUTH_UNIX &&
 197             flavor != RPC_AUTH_SHORT) {
 198                 printk("RPC: bad verf flavor: %u\n", flavor);
 199                 return NULL;
 200         }
 201
 202         size = ntohl(*p++);
 203         if (size > RPC_MAX_AUTH_SIZE) {
 204                 printk("RPC: giant verf size: %u\n", size);
 205                 return NULL;
 206         }
 207         task->tk_msg.rpc_cred->cr_auth->au_rslack = (size >> 2) + 2;
 208         p += (size >> 2);
 209
 210         return p;
 211 }
 212
 213 void __init rpc_init_authunix(void)
 214 {
 215         spin_lock_init(&unix_cred_cache.lock);
 216 }
 217
 218 const struct rpc_authops authunix_ops = {
 219         .owner          = THIS_MODULE,
 220         .au_flavor      = RPC_AUTH_UNIX,
 221 #ifdef RPC_DEBUG
 222         .au_name        = "UNIX",
 223 #endif
 224         .create         = unx_create,
 225         .destroy        = unx_destroy,
 226         .lookup_cred    = unx_lookup_cred,
 227         .crcreate       = unx_create_cred,
 228 };
 229
 230 static
 231 struct rpc_cred_cache   unix_cred_cache = {
 232 };
 233
 234 static
 235 struct rpc_auth         unix_auth = {
 236         .au_cslack      = UNX_WRITESLACK,
 237         .au_rslack      = 2,                    /* assume AUTH_NULL verf */
 238         .au_ops         = &authunix_ops,
 239         .au_flavor      = RPC_AUTH_UNIX,
 240         .au_count       = ATOMIC_INIT(0),
 241         .au_credcache   = &unix_cred_cache,
 242 };
 243
 244 static
 245 const struct rpc_credops unix_credops = {
 246         .cr_name        = "AUTH_UNIX",
 247         .crdestroy      = unx_destroy_cred,
 248         .crmatch        = unx_match,
 249         .crmarshal      = unx_marshal,
 250         .crrefresh      = unx_refresh,
 251         .crvalidate     = unx_validate,
 252 };