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 struct unx_cred {
  18         struct rpc_cred         uc_base;
  19         kgid_t                  uc_gid;
  20         kgid_t                  uc_gids[UNX_NGROUPS];
  21 };
  22 #define uc_uid                  uc_base.cr_uid
  23
  24 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
  25 # define RPCDBG_FACILITY        RPCDBG_AUTH
  26 #endif
  27
  28 static struct rpc_auth          unix_auth;
  29 static const struct rpc_credops unix_credops;
  30
  31 static struct rpc_auth *
  32 unx_create(struct rpc_auth_create_args *args, struct rpc_clnt *clnt)
  33 {
  34         dprintk("RPC:       creating UNIX authenticator for client %p\n",
  35                         clnt);
  36         atomic_inc(&unix_auth.au_count);
  37         return &unix_auth;
  38 }
  39
  40 static void
  41 unx_destroy(struct rpc_auth *auth)
  42 {
  43         dprintk("RPC:       destroying UNIX authenticator %p\n", auth);
  44         rpcauth_clear_credcache(auth->au_credcache);
  45 }
  46
  47 static int
  48 unx_hash_cred(struct auth_cred *acred, unsigned int hashbits)
  49 {
  50         return hash_64(from_kgid(&init_user_ns, acred->gid) |
  51                 ((u64)from_kuid(&init_user_ns, acred->uid) <<
  52                         (sizeof(gid_t) * 8)), hashbits);
  53 }
  54
  55 /*
  56  * Lookup AUTH_UNIX creds for current process
  57  */
  58 static struct rpc_cred *
  59 unx_lookup_cred(struct rpc_auth *auth, struct auth_cred *acred, int flags)
  60 {
  61         return rpcauth_lookup_credcache(auth, acred, flags, GFP_NOFS);
  62 }
  63
  64 static struct rpc_cred *
  65 unx_create_cred(struct rpc_auth *auth, struct auth_cred *acred, int flags, gfp_t gfp)
  66 {
  67         struct unx_cred *cred;
  68         unsigned int groups = 0;
  69         unsigned int i;
  70
  71         dprintk("RPC:       allocating UNIX cred for uid %d gid %d\n",
  72                         from_kuid(&init_user_ns, acred->uid),
  73                         from_kgid(&init_user_ns, acred->gid));
  74
  75         if (!(cred = kmalloc(sizeof(*cred), gfp)))
  76                 return ERR_PTR(-ENOMEM);
  77
  78         rpcauth_init_cred(&cred->uc_base, acred, auth, &unix_credops);
  79         cred->uc_base.cr_flags = 1UL << RPCAUTH_CRED_UPTODATE;
  80
  81         if (acred->group_info != NULL)
  82                 groups = acred->group_info->ngroups;
  83         if (groups > UNX_NGROUPS)
  84                 groups = UNX_NGROUPS;
  85
  86         cred->uc_gid = acred->gid;
  87         for (i = 0; i < groups; i++)
  88                 cred->uc_gids[i] = acred->group_info->gid[i];
  89         if (i < UNX_NGROUPS)
  90                 cred->uc_gids[i] = INVALID_GID;
  91
  92         return &cred->uc_base;
  93 }
  94
  95 static void
  96 unx_free_cred(struct unx_cred *unx_cred)
  97 {
  98         dprintk("RPC:       unx_free_cred %p\n", unx_cred);
  99         kfree(unx_cred);
 100 }
 101
 102 static void
 103 unx_free_cred_callback(struct rcu_head *head)
 104 {
 105         struct unx_cred *unx_cred = container_of(head, struct unx_cred, uc_base.cr_rcu);
 106         unx_free_cred(unx_cred);
 107 }
 108
 109 static void
 110 unx_destroy_cred(struct rpc_cred *cred)
 111 {
 112         call_rcu(&cred->cr_rcu, unx_free_cred_callback);
 113 }
 114
 115 /*
 116  * Match credentials against current process creds.
 117  * The root_override argument takes care of cases where the caller may
 118  * request root creds (e.g. for NFS swapping).
 119  */
 120 static int
 121 unx_match(struct auth_cred *acred, struct rpc_cred *rcred, int flags)
 122 {
 123         struct unx_cred *cred = container_of(rcred, struct unx_cred, uc_base);
 124         unsigned int groups = 0;
 125         unsigned int i;
 126
 127
 128         if (!uid_eq(cred->uc_uid, acred->uid) || !gid_eq(cred->uc_gid, acred->gid))
 129                 return 0;
 130
 131         if (acred->group_info != NULL)
 132                 groups = acred->group_info->ngroups;
 133         if (groups > UNX_NGROUPS)
 134                 groups = UNX_NGROUPS;
 135         for (i = 0; i < groups ; i++)
 136                 if (!gid_eq(cred->uc_gids[i], acred->group_info->gid[i]))
 137                         return 0;
 138         if (groups < UNX_NGROUPS && gid_valid(cred->uc_gids[groups]))
 139                 return 0;
 140         return 1;
 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_rqstp->rq_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) from_kuid(&init_user_ns, cred->uc_uid));
 165         *p++ = htonl((u32) from_kgid(&init_user_ns, cred->uc_gid));
 166         hold = p++;
 167         for (i = 0; i < UNX_NGROUPS && gid_valid(cred->uc_gids[i]); i++)
 168                 *p++ = htonl((u32) from_kgid(&init_user_ns, 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_rqstp->rq_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 ERR_PTR(-EIO);
 200         }
 201
 202         size = ntohl(*p++);
 203         if (size > RPC_MAX_AUTH_SIZE) {
 204                 printk("RPC: giant verf size: %u\n", size);
 205                 return ERR_PTR(-EIO);
 206         }
 207         task->tk_rqstp->rq_cred->cr_auth->au_rslack = (size >> 2) + 2;
 208         p += (size >> 2);
 209
 210         return p;
 211 }
 212
 213 int __init rpc_init_authunix(void)
 214 {
 215         return rpcauth_init_credcache(&unix_auth);
 216 }
 217
 218 void rpc_destroy_authunix(void)
 219 {
 220         rpcauth_destroy_credcache(&unix_auth);
 221 }
 222
 223 const struct rpc_authops authunix_ops = {
 224         .owner          = THIS_MODULE,
 225         .au_flavor      = RPC_AUTH_UNIX,
 226         .au_name        = "UNIX",
 227         .create         = unx_create,
 228         .destroy        = unx_destroy,
 229         .hash_cred      = unx_hash_cred,
 230         .lookup_cred    = unx_lookup_cred,
 231         .crcreate       = unx_create_cred,
 232 };
 233
 234 static
 235 struct rpc_auth         unix_auth = {
 236         .au_cslack      = UNX_CALLSLACK,
 237         .au_rslack      = NUL_REPLYSLACK,
 238         .au_flags       = RPCAUTH_AUTH_NO_CRKEY_TIMEOUT,
 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 };