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/slab.h>
  10 #include <linux/types.h>
  11 #include <linux/sched.h>
  12 #include <linux/module.h>
  13 #include <linux/sunrpc/clnt.h>
  14 #include <linux/sunrpc/auth.h>
  15 #include <linux/user_namespace.h>
  16
  17 #define NFS_NGROUPS     16
  18
  19 struct unx_cred {
  20         struct rpc_cred         uc_base;
  21         gid_t                   uc_gid;
  22         gid_t                   uc_gids[NFS_NGROUPS];
  23 };
  24 #define uc_uid                  uc_base.cr_uid
  25
  26 #define UNX_WRITESLACK          (21 + (UNX_MAXNODENAME >> 2))
  27
  28 #ifdef RPC_DEBUG
  29 # define RPCDBG_FACILITY        RPCDBG_AUTH
  30 #endif
  31
  32 static struct rpc_auth          unix_auth;
  33 static const struct rpc_credops unix_credops;
  34
  35 static struct rpc_auth *
  36 unx_create(struct rpc_clnt *clnt, rpc_authflavor_t flavor)
  37 {
  38         dprintk("RPC:       creating UNIX authenticator for client %p\n",
  39                         clnt);
  40         atomic_inc(&unix_auth.au_count);
  41         return &unix_auth;
  42 }
  43
  44 static void
  45 unx_destroy(struct rpc_auth *auth)
  46 {
  47         dprintk("RPC:       destroying UNIX authenticator %p\n", auth);
  48         rpcauth_clear_credcache(auth->au_credcache);
  49 }
  50
  51 /*
  52  * Lookup AUTH_UNIX creds for current process
  53  */
  54 static struct rpc_cred *
  55 unx_lookup_cred(struct rpc_auth *auth, struct auth_cred *acred, int flags)
  56 {
  57         return rpcauth_lookup_credcache(auth, acred, flags);
  58 }
  59
  60 static struct rpc_cred *
  61 unx_create_cred(struct rpc_auth *auth, struct auth_cred *acred, int flags)
  62 {
  63         struct unx_cred *cred;
  64         unsigned int groups = 0;
  65         unsigned int i;
  66
  67         dprintk("RPC:       allocating UNIX cred for uid %d gid %d\n",
  68                         acred->uid, acred->gid);
  69
  70         if (!(cred = kmalloc(sizeof(*cred), GFP_NOFS)))
  71                 return ERR_PTR(-ENOMEM);
  72
  73         rpcauth_init_cred(&cred->uc_base, acred, auth, &unix_credops);
  74         cred->uc_base.cr_flags = 1UL << RPCAUTH_CRED_UPTODATE;
  75
  76         if (acred->group_info != NULL)
  77                 groups = acred->group_info->ngroups;
  78         if (groups > NFS_NGROUPS)
  79                 groups = NFS_NGROUPS;
  80
  81         cred->uc_gid = acred->gid;
  82         for (i = 0; i < groups; i++) {
  83                 gid_t gid;
  84                 gid = from_kgid(&init_user_ns, GROUP_AT(acred->group_info, i));
  85                 cred->uc_gids[i] = gid;
  86         }
  87         if (i < NFS_NGROUPS)
  88                 cred->uc_gids[i] = NOGROUP;
  89
  90         return &cred->uc_base;
  91 }
  92
  93 static void
  94 unx_free_cred(struct unx_cred *unx_cred)
  95 {
  96         dprintk("RPC:       unx_free_cred %p\n", unx_cred);
  97         kfree(unx_cred);
  98 }
  99
 100 static void
 101 unx_free_cred_callback(struct rcu_head *head)
 102 {
 103         struct unx_cred *unx_cred = container_of(head, struct unx_cred, uc_base.cr_rcu);
 104         unx_free_cred(unx_cred);
 105 }
 106
 107 static void
 108 unx_destroy_cred(struct rpc_cred *cred)
 109 {
 110         call_rcu(&cred->cr_rcu, unx_free_cred_callback);
 111 }
 112
 113 /*
 114  * Match credentials against current process creds.
 115  * The root_override argument takes care of cases where the caller may
 116  * request root creds (e.g. for NFS swapping).
 117  */
 118 static int
 119 unx_match(struct auth_cred *acred, struct rpc_cred *rcred, int flags)
 120 {
 121         struct unx_cred *cred = container_of(rcred, struct unx_cred, uc_base);
 122         unsigned int groups = 0;
 123         unsigned int i;
 124
 125
 126         if (cred->uc_uid != acred->uid || cred->uc_gid != acred->gid)
 127                 return 0;
 128
 129         if (acred->group_info != NULL)
 130                 groups = acred->group_info->ngroups;
 131         if (groups > NFS_NGROUPS)
 132                 groups = NFS_NGROUPS;
 133         for (i = 0; i < groups ; i++) {
 134                 gid_t gid;
 135                 gid = from_kgid(&init_user_ns, GROUP_AT(acred->group_info, i));
 136                 if (cred->uc_gids[i] != gid)
 137                         return 0;
 138         }
 139         if (groups < NFS_NGROUPS &&
 140             cred->uc_gids[groups] != NOGROUP)
 141                 return 0;
 142         return 1;
 143 }
 144
 145 /*
 146  * Marshal credentials.
 147  * Maybe we should keep a cached credential for performance reasons.
 148  */
 149 static __be32 *
 150 unx_marshal(struct rpc_task *task, __be32 *p)
 151 {
 152         struct rpc_clnt *clnt = task->tk_client;
 153         struct unx_cred *cred = container_of(task->tk_rqstp->rq_cred, struct unx_cred, uc_base);
 154         __be32          *base, *hold;
 155         int             i;
 156
 157         *p++ = htonl(RPC_AUTH_UNIX);
 158         base = p++;
 159         *p++ = htonl(jiffies/HZ);
 160
 161         /*
 162          * Copy the UTS nodename captured when the client was created.
 163          */
 164         p = xdr_encode_array(p, clnt->cl_nodename, clnt->cl_nodelen);
 165
 166         *p++ = htonl((u32) cred->uc_uid);
 167         *p++ = htonl((u32) cred->uc_gid);
 168         hold = p++;
 169         for (i = 0; i < 16 && cred->uc_gids[i] != (gid_t) NOGROUP; i++)
 170                 *p++ = htonl((u32) cred->uc_gids[i]);
 171         *hold = htonl(p - hold - 1);            /* gid array length */
 172         *base = htonl((p - base - 1) << 2);     /* cred length */
 173
 174         *p++ = htonl(RPC_AUTH_NULL);
 175         *p++ = htonl(0);
 176
 177         return p;
 178 }
 179
 180 /*
 181  * Refresh credentials. This is a no-op for AUTH_UNIX
 182  */
 183 static int
 184 unx_refresh(struct rpc_task *task)
 185 {
 186         set_bit(RPCAUTH_CRED_UPTODATE, &task->tk_rqstp->rq_cred->cr_flags);
 187         return 0;
 188 }
 189
 190 static __be32 *
 191 unx_validate(struct rpc_task *task, __be32 *p)
 192 {
 193         rpc_authflavor_t        flavor;
 194         u32                     size;
 195
 196         flavor = ntohl(*p++);
 197         if (flavor != RPC_AUTH_NULL &&
 198             flavor != RPC_AUTH_UNIX &&
 199             flavor != RPC_AUTH_SHORT) {
 200                 printk("RPC: bad verf flavor: %u\n", flavor);
 201                 return NULL;
 202         }
 203
 204         size = ntohl(*p++);
 205         if (size > RPC_MAX_AUTH_SIZE) {
 206                 printk("RPC: giant verf size: %u\n", size);
 207                 return NULL;
 208         }
 209         task->tk_rqstp->rq_cred->cr_auth->au_rslack = (size >> 2) + 2;
 210         p += (size >> 2);
 211
 212         return p;
 213 }
 214
 215 int __init rpc_init_authunix(void)
 216 {
 217         return rpcauth_init_credcache(&unix_auth);
 218 }
 219
 220 void rpc_destroy_authunix(void)
 221 {
 222         rpcauth_destroy_credcache(&unix_auth);
 223 }
 224
 225 const struct rpc_authops authunix_ops = {
 226         .owner          = THIS_MODULE,
 227         .au_flavor      = RPC_AUTH_UNIX,
 228         .au_name        = "UNIX",
 229         .create         = unx_create,
 230         .destroy        = unx_destroy,
 231         .lookup_cred    = unx_lookup_cred,
 232         .crcreate       = unx_create_cred,
 233 };
 234
 235 static
 236 struct rpc_auth         unix_auth = {
 237         .au_cslack      = UNX_WRITESLACK,
 238         .au_rslack      = 2,                    /* assume AUTH_NULL verf */
 239         .au_ops         = &authunix_ops,
 240         .au_flavor      = RPC_AUTH_UNIX,
 241         .au_count       = ATOMIC_INIT(0),
 242 };
 243
 244 static
 245 const struct rpc_credops unix_credops = {
 246         .cr_name        = "AUTH_UNIX",
 247         .crdestroy      = unx_destroy_cred,
 248         .crbind         = rpcauth_generic_bind_cred,
 249         .crmatch        = unx_match,
 250         .crmarshal      = unx_marshal,
 251         .crrefresh      = unx_refresh,
 252         .crvalidate     = unx_validate,
 253 };