net/sunrpc/auth_unix.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * linux/net/sunrpc/auth_unix.c
   4  *
   5  * UNIX-style authentication; no AUTH_SHORT support
   6  *
   7  * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
   8  */
   9
  10 #include <linux/slab.h>
  11 #include <linux/types.h>
  12 #include <linux/sched.h>
  13 #include <linux/module.h>
  14 #include <linux/mempool.h>
  15 #include <linux/sunrpc/clnt.h>
  16 #include <linux/sunrpc/auth.h>
  17 #include <linux/user_namespace.h>
  18
  19
  20 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
  21 # define RPCDBG_FACILITY        RPCDBG_AUTH
  22 #endif
  23
  24 static struct rpc_auth          unix_auth;
  25 static const struct rpc_credops unix_credops;
  26 static mempool_t                *unix_pool;
  27
  28 static struct rpc_auth *
  29 unx_create(const struct rpc_auth_create_args *args, struct rpc_clnt *clnt)
  30 {
  31         refcount_inc(&unix_auth.au_count);
  32         return &unix_auth;
  33 }
  34
  35 static void
  36 unx_destroy(struct rpc_auth *auth)
  37 {
  38 }
  39
  40 /*
  41  * Lookup AUTH_UNIX creds for current process
  42  */
  43 static struct rpc_cred *unx_lookup_cred(struct rpc_auth *auth,
  44                                         struct auth_cred *acred, int flags)
  45 {
  46         struct rpc_cred *ret;
  47
  48         ret = kmalloc(sizeof(*ret), rpc_task_gfp_mask());
  49         if (!ret) {
  50                 if (!(flags & RPCAUTH_LOOKUP_ASYNC))
  51                         return ERR_PTR(-ENOMEM);
  52                 ret = mempool_alloc(unix_pool, GFP_NOWAIT);
  53                 if (!ret)
  54                         return ERR_PTR(-ENOMEM);
  55         }
  56         rpcauth_init_cred(ret, acred, auth, &unix_credops);
  57         ret->cr_flags = 1UL << RPCAUTH_CRED_UPTODATE;
  58         return ret;
  59 }
  60
  61 static void
  62 unx_free_cred_callback(struct rcu_head *head)
  63 {
  64         struct rpc_cred *rpc_cred = container_of(head, struct rpc_cred, cr_rcu);
  65
  66         put_cred(rpc_cred->cr_cred);
  67         mempool_free(rpc_cred, unix_pool);
  68 }
  69
  70 static void
  71 unx_destroy_cred(struct rpc_cred *cred)
  72 {
  73         call_rcu(&cred->cr_rcu, unx_free_cred_callback);
  74 }
  75
  76 /*
  77  * Match credentials against current the auth_cred.
  78  */
  79 static int
  80 unx_match(struct auth_cred *acred, struct rpc_cred *cred, int flags)
  81 {
  82         unsigned int groups = 0;
  83         unsigned int i;
  84
  85         if (cred->cr_cred == acred->cred)
  86                 return 1;
  87
  88         if (!uid_eq(cred->cr_cred->fsuid, acred->cred->fsuid) || !gid_eq(cred->cr_cred->fsgid, acred->cred->fsgid))
  89                 return 0;
  90
  91         if (acred->cred->group_info != NULL)
  92                 groups = acred->cred->group_info->ngroups;
  93         if (groups > UNX_NGROUPS)
  94                 groups = UNX_NGROUPS;
  95         if (cred->cr_cred->group_info == NULL)
  96                 return groups == 0;
  97         if (groups != cred->cr_cred->group_info->ngroups)
  98                 return 0;
  99
 100         for (i = 0; i < groups ; i++)
 101                 if (!gid_eq(cred->cr_cred->group_info->gid[i], acred->cred->group_info->gid[i]))
 102                         return 0;
 103         return 1;
 104 }
 105
 106 /*
 107  * Marshal credentials.
 108  * Maybe we should keep a cached credential for performance reasons.
 109  */
 110 static int
 111 unx_marshal(struct rpc_task *task, struct xdr_stream *xdr)
 112 {
 113         struct rpc_clnt *clnt = task->tk_client;
 114         struct rpc_cred *cred = task->tk_rqstp->rq_cred;
 115         __be32          *p, *cred_len, *gidarr_len;
 116         int             i;
 117         struct group_info *gi = cred->cr_cred->group_info;
 118         struct user_namespace *userns = clnt->cl_cred ?
 119                 clnt->cl_cred->user_ns : &init_user_ns;
 120
 121         /* Credential */
 122
 123         p = xdr_reserve_space(xdr, 3 * sizeof(*p));
 124         if (!p)
 125                 goto marshal_failed;
 126         *p++ = rpc_auth_unix;
 127         cred_len = p++;
 128         *p++ = xdr_zero;        /* stamp */
 129         if (xdr_stream_encode_opaque(xdr, clnt->cl_nodename,
 130                                      clnt->cl_nodelen) < 0)
 131                 goto marshal_failed;
 132         p = xdr_reserve_space(xdr, 3 * sizeof(*p));
 133         if (!p)
 134                 goto marshal_failed;
 135         *p++ = cpu_to_be32(from_kuid_munged(userns, cred->cr_cred->fsuid));
 136         *p++ = cpu_to_be32(from_kgid_munged(userns, cred->cr_cred->fsgid));
 137
 138         gidarr_len = p++;
 139         if (gi)
 140                 for (i = 0; i < UNX_NGROUPS && i < gi->ngroups; i++)
 141                         *p++ = cpu_to_be32(from_kgid_munged(userns, gi->gid[i]));
 142         *gidarr_len = cpu_to_be32(p - gidarr_len - 1);
 143         *cred_len = cpu_to_be32((p - cred_len - 1) << 2);
 144         p = xdr_reserve_space(xdr, (p - gidarr_len - 1) << 2);
 145         if (!p)
 146                 goto marshal_failed;
 147
 148         /* Verifier */
 149
 150         p = xdr_reserve_space(xdr, 2 * sizeof(*p));
 151         if (!p)
 152                 goto marshal_failed;
 153         *p++ = rpc_auth_null;
 154         *p   = xdr_zero;
 155
 156         return 0;
 157
 158 marshal_failed:
 159         return -EMSGSIZE;
 160 }
 161
 162 /*
 163  * Refresh credentials. This is a no-op for AUTH_UNIX
 164  */
 165 static int
 166 unx_refresh(struct rpc_task *task)
 167 {
 168         set_bit(RPCAUTH_CRED_UPTODATE, &task->tk_rqstp->rq_cred->cr_flags);
 169         return 0;
 170 }
 171
 172 static int
 173 unx_validate(struct rpc_task *task, struct xdr_stream *xdr)
 174 {
 175         struct rpc_auth *auth = task->tk_rqstp->rq_cred->cr_auth;
 176         __be32 *p;
 177         u32 size;
 178
 179         p = xdr_inline_decode(xdr, 2 * sizeof(*p));
 180         if (!p)
 181                 return -EIO;
 182         switch (*p++) {
 183         case rpc_auth_null:
 184         case rpc_auth_unix:
 185         case rpc_auth_short:
 186                 break;
 187         default:
 188                 return -EIO;
 189         }
 190         size = be32_to_cpup(p);
 191         if (size > RPC_MAX_AUTH_SIZE)
 192                 return -EIO;
 193         p = xdr_inline_decode(xdr, size);
 194         if (!p)
 195                 return -EIO;
 196
 197         auth->au_verfsize = XDR_QUADLEN(size) + 2;
 198         auth->au_rslack = XDR_QUADLEN(size) + 2;
 199         auth->au_ralign = XDR_QUADLEN(size) + 2;
 200         return 0;
 201 }
 202
 203 int __init rpc_init_authunix(void)
 204 {
 205         unix_pool = mempool_create_kmalloc_pool(16, sizeof(struct rpc_cred));
 206         return unix_pool ? 0 : -ENOMEM;
 207 }
 208
 209 void rpc_destroy_authunix(void)
 210 {
 211         mempool_destroy(unix_pool);
 212 }
 213
 214 const struct rpc_authops authunix_ops = {
 215         .owner          = THIS_MODULE,
 216         .au_flavor      = RPC_AUTH_UNIX,
 217         .au_name        = "UNIX",
 218         .create         = unx_create,
 219         .destroy        = unx_destroy,
 220         .lookup_cred    = unx_lookup_cred,
 221 };
 222
 223 static
 224 struct rpc_auth         unix_auth = {
 225         .au_cslack      = UNX_CALLSLACK,
 226         .au_rslack      = NUL_REPLYSLACK,
 227         .au_verfsize    = NUL_REPLYSLACK,
 228         .au_ops         = &authunix_ops,
 229         .au_flavor      = RPC_AUTH_UNIX,
 230         .au_count       = REFCOUNT_INIT(1),
 231 };
 232
 233 static
 234 const struct rpc_credops unix_credops = {
 235         .cr_name        = "AUTH_UNIX",
 236         .crdestroy      = unx_destroy_cred,
 237         .crmatch        = unx_match,
 238         .crmarshal      = unx_marshal,
 239         .crwrap_req     = rpcauth_wrap_req_encode,
 240         .crrefresh      = unx_refresh,
 241         .crvalidate     = unx_validate,
 242         .crunwrap_resp  = rpcauth_unwrap_resp_decode,
 243 };