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 *
  44 unx_lookup_cred(struct rpc_auth *auth, struct auth_cred *acred, int flags)
  45 {
  46         struct rpc_cred *ret = mempool_alloc(unix_pool, GFP_NOFS);
  47
  48         rpcauth_init_cred(ret, acred, auth, &unix_credops);
  49         ret->cr_flags = 1UL << RPCAUTH_CRED_UPTODATE;
  50         return ret;
  51 }
  52
  53 static void
  54 unx_free_cred_callback(struct rcu_head *head)
  55 {
  56         struct rpc_cred *rpc_cred = container_of(head, struct rpc_cred, cr_rcu);
  57
  58         put_cred(rpc_cred->cr_cred);
  59         mempool_free(rpc_cred, unix_pool);
  60 }
  61
  62 static void
  63 unx_destroy_cred(struct rpc_cred *cred)
  64 {
  65         call_rcu(&cred->cr_rcu, unx_free_cred_callback);
  66 }
  67
  68 /*
  69  * Match credentials against current the auth_cred.
  70  */
  71 static int
  72 unx_match(struct auth_cred *acred, struct rpc_cred *cred, int flags)
  73 {
  74         unsigned int groups = 0;
  75         unsigned int i;
  76
  77         if (cred->cr_cred == acred->cred)
  78                 return 1;
  79
  80         if (!uid_eq(cred->cr_cred->fsuid, acred->cred->fsuid) || !gid_eq(cred->cr_cred->fsgid, acred->cred->fsgid))
  81                 return 0;
  82
  83         if (acred->cred->group_info != NULL)
  84                 groups = acred->cred->group_info->ngroups;
  85         if (groups > UNX_NGROUPS)
  86                 groups = UNX_NGROUPS;
  87         if (cred->cr_cred->group_info == NULL)
  88                 return groups == 0;
  89         if (groups != cred->cr_cred->group_info->ngroups)
  90                 return 0;
  91
  92         for (i = 0; i < groups ; i++)
  93                 if (!gid_eq(cred->cr_cred->group_info->gid[i], acred->cred->group_info->gid[i]))
  94                         return 0;
  95         return 1;
  96 }
  97
  98 /*
  99  * Marshal credentials.
 100  * Maybe we should keep a cached credential for performance reasons.
 101  */
 102 static int
 103 unx_marshal(struct rpc_task *task, struct xdr_stream *xdr)
 104 {
 105         struct rpc_clnt *clnt = task->tk_client;
 106         struct rpc_cred *cred = task->tk_rqstp->rq_cred;
 107         __be32          *p, *cred_len, *gidarr_len;
 108         int             i;
 109         struct group_info *gi = cred->cr_cred->group_info;
 110         struct user_namespace *userns = clnt->cl_cred ?
 111                 clnt->cl_cred->user_ns : &init_user_ns;
 112
 113         /* Credential */
 114
 115         p = xdr_reserve_space(xdr, 3 * sizeof(*p));
 116         if (!p)
 117                 goto marshal_failed;
 118         *p++ = rpc_auth_unix;
 119         cred_len = p++;
 120         *p++ = xdr_zero;        /* stamp */
 121         if (xdr_stream_encode_opaque(xdr, clnt->cl_nodename,
 122                                      clnt->cl_nodelen) < 0)
 123                 goto marshal_failed;
 124         p = xdr_reserve_space(xdr, 3 * sizeof(*p));
 125         if (!p)
 126                 goto marshal_failed;
 127         *p++ = cpu_to_be32(from_kuid_munged(userns, cred->cr_cred->fsuid));
 128         *p++ = cpu_to_be32(from_kgid_munged(userns, cred->cr_cred->fsgid));
 129
 130         gidarr_len = p++;
 131         if (gi)
 132                 for (i = 0; i < UNX_NGROUPS && i < gi->ngroups; i++)
 133                         *p++ = cpu_to_be32(from_kgid_munged(userns, gi->gid[i]));
 134         *gidarr_len = cpu_to_be32(p - gidarr_len - 1);
 135         *cred_len = cpu_to_be32((p - cred_len - 1) << 2);
 136         p = xdr_reserve_space(xdr, (p - gidarr_len - 1) << 2);
 137         if (!p)
 138                 goto marshal_failed;
 139
 140         /* Verifier */
 141
 142         p = xdr_reserve_space(xdr, 2 * sizeof(*p));
 143         if (!p)
 144                 goto marshal_failed;
 145         *p++ = rpc_auth_null;
 146         *p   = xdr_zero;
 147
 148         return 0;
 149
 150 marshal_failed:
 151         return -EMSGSIZE;
 152 }
 153
 154 /*
 155  * Refresh credentials. This is a no-op for AUTH_UNIX
 156  */
 157 static int
 158 unx_refresh(struct rpc_task *task)
 159 {
 160         set_bit(RPCAUTH_CRED_UPTODATE, &task->tk_rqstp->rq_cred->cr_flags);
 161         return 0;
 162 }
 163
 164 static int
 165 unx_validate(struct rpc_task *task, struct xdr_stream *xdr)
 166 {
 167         struct rpc_auth *auth = task->tk_rqstp->rq_cred->cr_auth;
 168         __be32 *p;
 169         u32 size;
 170
 171         p = xdr_inline_decode(xdr, 2 * sizeof(*p));
 172         if (!p)
 173                 return -EIO;
 174         switch (*p++) {
 175         case rpc_auth_null:
 176         case rpc_auth_unix:
 177         case rpc_auth_short:
 178                 break;
 179         default:
 180                 return -EIO;
 181         }
 182         size = be32_to_cpup(p);
 183         if (size > RPC_MAX_AUTH_SIZE)
 184                 return -EIO;
 185         p = xdr_inline_decode(xdr, size);
 186         if (!p)
 187                 return -EIO;
 188
 189         auth->au_verfsize = XDR_QUADLEN(size) + 2;
 190         auth->au_rslack = XDR_QUADLEN(size) + 2;
 191         auth->au_ralign = XDR_QUADLEN(size) + 2;
 192         return 0;
 193 }
 194
 195 int __init rpc_init_authunix(void)
 196 {
 197         unix_pool = mempool_create_kmalloc_pool(16, sizeof(struct rpc_cred));
 198         return unix_pool ? 0 : -ENOMEM;
 199 }
 200
 201 void rpc_destroy_authunix(void)
 202 {
 203         mempool_destroy(unix_pool);
 204 }
 205
 206 const struct rpc_authops authunix_ops = {
 207         .owner          = THIS_MODULE,
 208         .au_flavor      = RPC_AUTH_UNIX,
 209         .au_name        = "UNIX",
 210         .create         = unx_create,
 211         .destroy        = unx_destroy,
 212         .lookup_cred    = unx_lookup_cred,
 213 };
 214
 215 static
 216 struct rpc_auth         unix_auth = {
 217         .au_cslack      = UNX_CALLSLACK,
 218         .au_rslack      = NUL_REPLYSLACK,
 219         .au_verfsize    = NUL_REPLYSLACK,
 220         .au_ops         = &authunix_ops,
 221         .au_flavor      = RPC_AUTH_UNIX,
 222         .au_count       = REFCOUNT_INIT(1),
 223 };
 224
 225 static
 226 const struct rpc_credops unix_credops = {
 227         .cr_name        = "AUTH_UNIX",
 228         .crdestroy      = unx_destroy_cred,
 229         .crmatch        = unx_match,
 230         .crmarshal      = unx_marshal,
 231         .crwrap_req     = rpcauth_wrap_req_encode,
 232         .crrefresh      = unx_refresh,
 233         .crvalidate     = unx_validate,
 234         .crunwrap_resp  = rpcauth_unwrap_resp_decode,
 235 };