net/sunrpc/auth_unix.c

   1 /*
   2  * linux/net/sunrpc/rpcauth_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/slab.h>
  11 #include <linux/socket.h>
  12 #include <linux/in.h>
  13 #include <linux/sunrpc/clnt.h>
  14 #include <linux/sunrpc/auth.h>
  15
  16 #define NFS_NGROUPS     16
  17 struct unx_cred {
  18         struct rpc_cred         uc_base;
  19         uid_t                   uc_fsuid;
  20         gid_t                   uc_gid, uc_fsgid;
  21         gid_t                   uc_gids[NFS_NGROUPS];
  22 };
  23 #define uc_uid                  uc_base.cr_uid
  24 #define uc_count                uc_base.cr_count
  25 #define uc_flags                uc_base.cr_flags
  26 #define uc_expire               uc_base.cr_expire
  27
  28 #define UNX_CRED_EXPIRE         (60 * HZ)
  29
  30 #define UNX_WRITESLACK          (21 + (UNX_MAXNODENAME >> 2))
  31
  32 #ifdef RPC_DEBUG
  33 # define RPCDBG_FACILITY        RPCDBG_AUTH
  34 #endif
  35
  36 static struct rpc_credops       unix_credops;
  37
  38 static struct rpc_auth *
  39 unx_create(struct rpc_clnt *clnt)
  40 {
  41         struct rpc_auth *auth;
  42
  43         dprintk("RPC: creating UNIX authenticator for client %p\n", clnt);
  44         if (!(auth = (struct rpc_auth *) rpc_allocate(0, sizeof(*auth))))
  45                 return NULL;
  46         auth->au_cslack = UNX_WRITESLACK;
  47         auth->au_rslack = 2;    /* assume AUTH_NULL verf */
  48         auth->au_expire = UNX_CRED_EXPIRE;
  49         auth->au_ops = &authunix_ops;
  50
  51         rpcauth_init_credcache(auth);
  52
  53         return auth;
  54 }
  55
  56 static void
  57 unx_destroy(struct rpc_auth *auth)
  58 {
  59         dprintk("RPC: destroying UNIX authenticator %p\n", auth);
  60         rpcauth_free_credcache(auth);
  61         rpc_free(auth);
  62 }
  63
  64 static struct rpc_cred *
  65 unx_create_cred(int flags)
  66 {
  67         struct unx_cred *cred;
  68         int             i;
  69
  70         dprintk("RPC:      allocating UNIX cred for uid %d gid %d\n",
  71                                 current->uid, current->gid);
  72
  73         if (!(cred = (struct unx_cred *) rpc_allocate(flags, sizeof(*cred))))
  74                 return NULL;
  75
  76         atomic_set(&cred->uc_count, 0);
  77         cred->uc_flags = RPCAUTH_CRED_UPTODATE;
  78         if (flags & RPC_TASK_ROOTCREDS) {
  79                 cred->uc_uid = cred->uc_fsuid = 0;
  80                 cred->uc_gid = cred->uc_fsgid = 0;
  81                 cred->uc_gids[0] = NOGROUP;
  82         } else {
  83                 int groups = current->ngroups;
  84                 if (groups > NFS_NGROUPS)
  85                         groups = NFS_NGROUPS;
  86
  87                 cred->uc_uid = current->uid;
  88                 cred->uc_gid = current->gid;
  89                 cred->uc_fsuid = current->fsuid;
  90                 cred->uc_fsgid = current->fsgid;
  91                 for (i = 0; i < groups; i++)
  92                         cred->uc_gids[i] = (gid_t) current->groups[i];
  93                 if (i < NFS_NGROUPS)
  94                   cred->uc_gids[i] = NOGROUP;
  95         }
  96         cred->uc_base.cr_ops = &unix_credops;
  97
  98         return (struct rpc_cred *) cred;
  99 }
 100
 101 struct rpc_cred *
 102 authunix_fake_cred(struct rpc_task *task, uid_t uid, gid_t gid)
 103 {
 104         struct unx_cred *cred;
 105
 106         dprintk("RPC:      allocating fake UNIX cred for uid %d gid %d\n",
 107                                 uid, gid);
 108
 109         if (!(cred = (struct unx_cred *) rpc_malloc(task, sizeof(*cred))))
 110                 return NULL;
 111
 112         atomic_set(&cred->uc_count, 1);
 113         cred->uc_flags = RPCAUTH_CRED_DEAD|RPCAUTH_CRED_UPTODATE;
 114         cred->uc_uid   = uid;
 115         cred->uc_gid   = gid;
 116         cred->uc_fsuid = uid;
 117         cred->uc_fsgid = gid;
 118         cred->uc_gids[0] = (gid_t) NOGROUP;
 119
 120         return task->tk_msg.rpc_cred = (struct rpc_cred *) cred;
 121 }
 122
 123 static void
 124 unx_destroy_cred(struct rpc_cred *cred)
 125 {
 126         rpc_free(cred);
 127 }
 128
 129 /*
 130  * Match credentials against current process creds.
 131  * The root_override argument takes care of cases where the caller may
 132  * request root creds (e.g. for NFS swapping).
 133  */
 134 static int
 135 unx_match(struct rpc_cred *rcred, int taskflags)
 136 {
 137         struct unx_cred *cred = (struct unx_cred *) rcred;
 138         int             i;
 139
 140         if (!(taskflags & RPC_TASK_ROOTCREDS)) {
 141                 int groups;
 142
 143                 if (cred->uc_uid != current->uid
 144                  || cred->uc_gid != current->gid
 145                  || cred->uc_fsuid != current->fsuid
 146                  || cred->uc_fsgid != current->fsgid)
 147                         return 0;
 148
 149                 groups = current->ngroups;
 150                 if (groups > NFS_NGROUPS)
 151                         groups = NFS_NGROUPS;
 152                 for (i = 0; i < groups ; i++)
 153                         if (cred->uc_gids[i] != (gid_t) current->groups[i])
 154                                 return 0;
 155                 return 1;
 156         }
 157         return (cred->uc_uid == 0 && cred->uc_fsuid == 0
 158              && cred->uc_gid == 0 && cred->uc_fsgid == 0
 159              && cred->uc_gids[0] == (gid_t) NOGROUP);
 160 }
 161
 162 /*
 163  * Marshal credentials.
 164  * Maybe we should keep a cached credential for performance reasons.
 165  */
 166 static u32 *
 167 unx_marshal(struct rpc_task *task, u32 *p, int ruid)
 168 {
 169         struct rpc_clnt *clnt = task->tk_client;
 170         struct unx_cred *cred = (struct unx_cred *) task->tk_msg.rpc_cred;
 171         u32             *base, *hold;
 172         int             i, n;
 173
 174         *p++ = htonl(RPC_AUTH_UNIX);
 175         base = p++;
 176         *p++ = htonl(jiffies/HZ);
 177
 178         /*
 179          * Copy the UTS nodename captured when the client was created.
 180          */
 181         n = clnt->cl_nodelen;
 182         *p++ = htonl(n);
 183         memcpy(p, clnt->cl_nodename, n);
 184         p += (n + 3) >> 2;
 185
 186         /* Note: we don't use real uid if it involves raising priviledge */
 187         if (ruid && cred->uc_uid != 0 && cred->uc_gid != 0) {
 188                 *p++ = htonl((u32) cred->uc_uid);
 189                 *p++ = htonl((u32) cred->uc_gid);
 190         } else {
 191                 *p++ = htonl((u32) cred->uc_fsuid);
 192                 *p++ = htonl((u32) cred->uc_fsgid);
 193         }
 194         hold = p++;
 195         for (i = 0; i < 16 && cred->uc_gids[i] != (gid_t) NOGROUP; i++)
 196                 *p++ = htonl((u32) cred->uc_gids[i]);
 197         *hold = htonl(p - hold - 1);            /* gid array length */
 198         *base = htonl((p - base - 1) << 2);     /* cred length */
 199
 200         *p++ = htonl(RPC_AUTH_NULL);
 201         *p++ = htonl(0);
 202
 203         return p;
 204 }
 205
 206 /*
 207  * Refresh credentials. This is a no-op for AUTH_UNIX
 208  */
 209 static int
 210 unx_refresh(struct rpc_task *task)
 211 {
 212         task->tk_msg.rpc_cred->cr_flags |= RPCAUTH_CRED_UPTODATE;
 213         return task->tk_status = -EACCES;
 214 }
 215
 216 static u32 *
 217 unx_validate(struct rpc_task *task, u32 *p)
 218 {
 219         u32             n = ntohl(*p++);
 220
 221         if (n != RPC_AUTH_NULL && n != RPC_AUTH_UNIX && n != RPC_AUTH_SHORT) {
 222                 printk("RPC: bad verf flavor: %ld\n", (unsigned long) n);
 223                 return NULL;
 224         }
 225         if ((n = ntohl(*p++)) > 400) {
 226                 printk("RPC: giant verf size: %ld\n", (unsigned long) n);
 227                 return NULL;
 228         }
 229         task->tk_auth->au_rslack = (n >> 2) + 2;
 230         p += (n >> 2);
 231
 232         return p;
 233 }
 234
 235 struct rpc_authops      authunix_ops = {
 236         RPC_AUTH_UNIX,
 237 #ifdef RPC_DEBUG
 238         "UNIX",
 239 #endif
 240         unx_create,
 241         unx_destroy,
 242         unx_create_cred
 243 };
 244
 245 static
 246 struct rpc_credops      unix_credops = {
 247         unx_destroy_cred,
 248         unx_match,
 249         unx_marshal,
 250         unx_refresh,
 251         unx_validate
 252 };