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         dprintk("RPC:       creating UNIX authenticator for client %p\n",
  32                         clnt);
  33         refcount_inc(&unix_auth.au_count);
  34         return &unix_auth;
  35 }
  36
  37 static void
  38 unx_destroy(struct rpc_auth *auth)
  39 {
  40         dprintk("RPC:       destroying UNIX authenticator %p\n", auth);
  41 }
  42
  43 /*
  44  * Lookup AUTH_UNIX creds for current process
  45  */
  46 static struct rpc_cred *
  47 unx_lookup_cred(struct rpc_auth *auth, struct auth_cred *acred, int flags)
  48 {
  49         struct rpc_cred *ret = mempool_alloc(unix_pool, GFP_NOFS);
  50
  51         dprintk("RPC:       allocating UNIX cred for uid %d gid %d\n",
  52                         from_kuid(&init_user_ns, acred->cred->fsuid),
  53                         from_kgid(&init_user_ns, acred->cred->fsgid));
  54
  55         rpcauth_init_cred(ret, acred, auth, &unix_credops);
  56         ret->cr_flags = 1UL << RPCAUTH_CRED_UPTODATE;
  57         return ret;
  58 }
  59
  60 static void
  61 unx_free_cred_callback(struct rcu_head *head)
  62 {
  63         struct rpc_cred *rpc_cred = container_of(head, struct rpc_cred, cr_rcu);
  64         dprintk("RPC:       unx_free_cred %p\n", rpc_cred);
  65         put_cred(rpc_cred->cr_cred);
  66         mempool_free(rpc_cred, unix_pool);
  67 }
  68
  69 static void
  70 unx_destroy_cred(struct rpc_cred *cred)
  71 {
  72         call_rcu(&cred->cr_rcu, unx_free_cred_callback);
  73 }
  74
  75 /*
  76  * Match credentials against current the auth_cred.
  77  */
  78 static int
  79 unx_match(struct auth_cred *acred, struct rpc_cred *cred, int flags)
  80 {
  81         unsigned int groups = 0;
  82         unsigned int i;
  83
  84         if (cred->cr_cred == acred->cred)
  85                 return 1;
  86
  87         if (!uid_eq(cred->cr_cred->fsuid, acred->cred->fsuid) || !gid_eq(cred->cr_cred->fsgid, acred->cred->fsgid))
  88                 return 0;
  89
  90         if (acred->cred && acred->cred->group_info != NULL)
  91                 groups = acred->cred->group_info->ngroups;
  92         if (groups > UNX_NGROUPS)
  93                 groups = UNX_NGROUPS;
  94         if (cred->cr_cred->group_info == NULL)
  95                 return groups == 0;
  96         if (groups != cred->cr_cred->group_info->ngroups)
  97                 return 0;
  98
  99         for (i = 0; i < groups ; i++)
 100                 if (!gid_eq(cred->cr_cred->group_info->gid[i], acred->cred->group_info->gid[i]))
 101                         return 0;
 102         return 1;
 103 }
 104
 105 /*
 106  * Marshal credentials.
 107  * Maybe we should keep a cached credential for performance reasons.
 108  */
 109 static __be32 *
 110 unx_marshal(struct rpc_task *task, __be32 *p)
 111 {
 112         struct rpc_clnt *clnt = task->tk_client;
 113         struct rpc_cred *cred = task->tk_rqstp->rq_cred;
 114         __be32          *base, *hold;
 115         int             i;
 116         struct group_info *gi = cred->cr_cred->group_info;
 117
 118         *p++ = htonl(RPC_AUTH_UNIX);
 119         base = p++;
 120         *p++ = htonl(jiffies/HZ);
 121
 122         /*
 123          * Copy the UTS nodename captured when the client was created.
 124          */
 125         p = xdr_encode_array(p, clnt->cl_nodename, clnt->cl_nodelen);
 126
 127         *p++ = htonl((u32) from_kuid(&init_user_ns, cred->cr_cred->fsuid));
 128         *p++ = htonl((u32) from_kgid(&init_user_ns, cred->cr_cred->fsgid));
 129         hold = p++;
 130         if (gi)
 131                 for (i = 0; i < UNX_NGROUPS && i < gi->ngroups; i++)
 132                         *p++ = htonl((u32) from_kgid(&init_user_ns, gi->gid[i]));
 133         *hold = htonl(p - hold - 1);            /* gid array length */
 134         *base = htonl((p - base - 1) << 2);     /* cred length */
 135
 136         *p++ = htonl(RPC_AUTH_NULL);
 137         *p++ = htonl(0);
 138
 139         return p;
 140 }
 141
 142 /*
 143  * Refresh credentials. This is a no-op for AUTH_UNIX
 144  */
 145 static int
 146 unx_refresh(struct rpc_task *task)
 147 {
 148         set_bit(RPCAUTH_CRED_UPTODATE, &task->tk_rqstp->rq_cred->cr_flags);
 149         return 0;
 150 }
 151
 152 static __be32 *
 153 unx_validate(struct rpc_task *task, __be32 *p)
 154 {
 155         rpc_authflavor_t        flavor;
 156         u32                     size;
 157
 158         flavor = ntohl(*p++);
 159         if (flavor != RPC_AUTH_NULL &&
 160             flavor != RPC_AUTH_UNIX &&
 161             flavor != RPC_AUTH_SHORT) {
 162                 printk("RPC: bad verf flavor: %u\n", flavor);
 163                 return ERR_PTR(-EIO);
 164         }
 165
 166         size = ntohl(*p++);
 167         if (size > RPC_MAX_AUTH_SIZE) {
 168                 printk("RPC: giant verf size: %u\n", size);
 169                 return ERR_PTR(-EIO);
 170         }
 171         task->tk_rqstp->rq_cred->cr_auth->au_rslack = (size >> 2) + 2;
 172         p += (size >> 2);
 173
 174         return p;
 175 }
 176
 177 int __init rpc_init_authunix(void)
 178 {
 179         unix_pool = mempool_create_kmalloc_pool(16, sizeof(struct rpc_cred));
 180         return unix_pool ? 0 : -ENOMEM;
 181 }
 182
 183 void rpc_destroy_authunix(void)
 184 {
 185         mempool_destroy(unix_pool);
 186 }
 187
 188 const struct rpc_authops authunix_ops = {
 189         .owner          = THIS_MODULE,
 190         .au_flavor      = RPC_AUTH_UNIX,
 191         .au_name        = "UNIX",
 192         .create         = unx_create,
 193         .destroy        = unx_destroy,
 194         .lookup_cred    = unx_lookup_cred,
 195 };
 196
 197 static
 198 struct rpc_auth         unix_auth = {
 199         .au_cslack      = UNX_CALLSLACK,
 200         .au_rslack      = NUL_REPLYSLACK,
 201         .au_ops         = &authunix_ops,
 202         .au_flavor      = RPC_AUTH_UNIX,
 203         .au_count       = REFCOUNT_INIT(1),
 204 };
 205
 206 static
 207 const struct rpc_credops unix_credops = {
 208         .cr_name        = "AUTH_UNIX",
 209         .crdestroy      = unx_destroy_cred,
 210         .crmatch        = unx_match,
 211         .crmarshal      = unx_marshal,
 212         .crrefresh      = unx_refresh,
 213         .crvalidate     = unx_validate,
 214 };