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         kgid_t                  uc_gid;
  22         kgid_t                  uc_gids[NFS_NGROUPS];
  23 };
  24 #define uc_uid                  uc_base.cr_uid
  25
  26 #define UNX_WRITESLACK          (21 + XDR_QUADLEN(UNX_MAXNODENAME))
  27
  28 #if IS_ENABLED(CONFIG_SUNRPC_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_auth_create_args *args, struct rpc_clnt *clnt)
  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                         from_kuid(&init_user_ns, acred->uid),
  69                         from_kgid(&init_user_ns, acred->gid));
  70
  71         if (!(cred = kmalloc(sizeof(*cred), GFP_NOFS)))
  72                 return ERR_PTR(-ENOMEM);
  73
  74         rpcauth_init_cred(&cred->uc_base, acred, auth, &unix_credops);
  75         cred->uc_base.cr_flags = 1UL << RPCAUTH_CRED_UPTODATE;
  76
  77         if (acred->group_info != NULL)
  78                 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] = INVALID_GID;
  87
  88         return &cred->uc_base;
  89 }
  90
  91 static void
  92 unx_free_cred(struct unx_cred *unx_cred)
  93 {
  94         dprintk("RPC:       unx_free_cred %p\n", unx_cred);
  95         kfree(unx_cred);
  96 }
  97
  98 static void
  99 unx_free_cred_callback(struct rcu_head *head)
 100 {
 101         struct unx_cred *unx_cred = container_of(head, struct unx_cred, uc_base.cr_rcu);
 102         unx_free_cred(unx_cred);
 103 }
 104
 105 static void
 106 unx_destroy_cred(struct rpc_cred *cred)
 107 {
 108         call_rcu(&cred->cr_rcu, unx_free_cred_callback);
 109 }
 110
 111 /*
 112  * Match credentials against current process creds.
 113  * The root_override argument takes care of cases where the caller may
 114  * request root creds (e.g. for NFS swapping).
 115  */
 116 static int
 117 unx_match(struct auth_cred *acred, struct rpc_cred *rcred, int flags)
 118 {
 119         struct unx_cred *cred = container_of(rcred, struct unx_cred, uc_base);
 120         unsigned int groups = 0;
 121         unsigned int i;
 122
 123
 124         if (!uid_eq(cred->uc_uid, acred->uid) || !gid_eq(cred->uc_gid, acred->gid))
 125                 return 0;
 126
 127         if (acred->group_info != NULL)
 128                 groups = acred->group_info->ngroups;
 129         if (groups > NFS_NGROUPS)
 130                 groups = NFS_NGROUPS;
 131         for (i = 0; i < groups ; i++)
 132                 if (!gid_eq(cred->uc_gids[i], GROUP_AT(acred->group_info, i)))
 133                         return 0;
 134         if (groups < NFS_NGROUPS && gid_valid(cred->uc_gids[groups]))
 135                 return 0;
 136         return 1;
 137 }
 138
 139 /*
 140  * Marshal credentials.
 141  * Maybe we should keep a cached credential for performance reasons.
 142  */
 143 static __be32 *
 144 unx_marshal(struct rpc_task *task, __be32 *p)
 145 {
 146         struct rpc_clnt *clnt = task->tk_client;
 147         struct unx_cred *cred = container_of(task->tk_rqstp->rq_cred, struct unx_cred, uc_base);
 148         __be32          *base, *hold;
 149         int             i;
 150
 151         *p++ = htonl(RPC_AUTH_UNIX);
 152         base = p++;
 153         *p++ = htonl(jiffies/HZ);
 154
 155         /*
 156          * Copy the UTS nodename captured when the client was created.
 157          */
 158         p = xdr_encode_array(p, clnt->cl_nodename, clnt->cl_nodelen);
 159
 160         *p++ = htonl((u32) from_kuid(&init_user_ns, cred->uc_uid));
 161         *p++ = htonl((u32) from_kgid(&init_user_ns, cred->uc_gid));
 162         hold = p++;
 163         for (i = 0; i < 16 && gid_valid(cred->uc_gids[i]); i++)
 164                 *p++ = htonl((u32) from_kgid(&init_user_ns, cred->uc_gids[i]));
 165         *hold = htonl(p - hold - 1);            /* gid array length */
 166         *base = htonl((p - base - 1) << 2);     /* cred length */
 167
 168         *p++ = htonl(RPC_AUTH_NULL);
 169         *p++ = htonl(0);
 170
 171         return p;
 172 }
 173
 174 /*
 175  * Refresh credentials. This is a no-op for AUTH_UNIX
 176  */
 177 static int
 178 unx_refresh(struct rpc_task *task)
 179 {
 180         set_bit(RPCAUTH_CRED_UPTODATE, &task->tk_rqstp->rq_cred->cr_flags);
 181         return 0;
 182 }
 183
 184 static __be32 *
 185 unx_validate(struct rpc_task *task, __be32 *p)
 186 {
 187         rpc_authflavor_t        flavor;
 188         u32                     size;
 189
 190         flavor = ntohl(*p++);
 191         if (flavor != RPC_AUTH_NULL &&
 192             flavor != RPC_AUTH_UNIX &&
 193             flavor != RPC_AUTH_SHORT) {
 194                 printk("RPC: bad verf flavor: %u\n", flavor);
 195                 return ERR_PTR(-EIO);
 196         }
 197
 198         size = ntohl(*p++);
 199         if (size > RPC_MAX_AUTH_SIZE) {
 200                 printk("RPC: giant verf size: %u\n", size);
 201                 return ERR_PTR(-EIO);
 202         }
 203         task->tk_rqstp->rq_cred->cr_auth->au_rslack = (size >> 2) + 2;
 204         p += (size >> 2);
 205
 206         return p;
 207 }
 208
 209 int __init rpc_init_authunix(void)
 210 {
 211         return rpcauth_init_credcache(&unix_auth);
 212 }
 213
 214 void rpc_destroy_authunix(void)
 215 {
 216         rpcauth_destroy_credcache(&unix_auth);
 217 }
 218
 219 const struct rpc_authops authunix_ops = {
 220         .owner          = THIS_MODULE,
 221         .au_flavor      = RPC_AUTH_UNIX,
 222         .au_name        = "UNIX",
 223         .create         = unx_create,
 224         .destroy        = unx_destroy,
 225         .lookup_cred    = unx_lookup_cred,
 226         .crcreate       = unx_create_cred,
 227 };
 228
 229 static
 230 struct rpc_auth         unix_auth = {
 231         .au_cslack      = UNX_WRITESLACK,
 232         .au_rslack      = 2,                    /* assume AUTH_NULL verf */
 233         .au_ops         = &authunix_ops,
 234         .au_flavor      = RPC_AUTH_UNIX,
 235         .au_count       = ATOMIC_INIT(0),
 236 };
 237
 238 static
 239 const struct rpc_credops unix_credops = {
 240         .cr_name        = "AUTH_UNIX",
 241         .crdestroy      = unx_destroy_cred,
 242         .crbind         = rpcauth_generic_bind_cred,
 243         .crmatch        = unx_match,
 244         .crmarshal      = unx_marshal,
 245         .crrefresh      = unx_refresh,
 246         .crvalidate     = unx_validate,
 247 };