linux/net/sunrpc/auth_unix.c
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   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
  19struct unx_cred {
  20        struct rpc_cred         uc_base;
  21        gid_t                   uc_gid;
  22        gid_t                   uc_gids[NFS_NGROUPS];
  23};
  24#define uc_uid                  uc_base.cr_uid
  25
  26#define UNX_WRITESLACK          (21 + (UNX_MAXNODENAME >> 2))
  27
  28#ifdef RPC_DEBUG
  29# define RPCDBG_FACILITY        RPCDBG_AUTH
  30#endif
  31
  32static struct rpc_auth          unix_auth;
  33static const struct rpc_credops unix_credops;
  34
  35static struct rpc_auth *
  36unx_create(struct rpc_clnt *clnt, rpc_authflavor_t flavor)
  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
  44static void
  45unx_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 */
  54static struct rpc_cred *
  55unx_lookup_cred(struct rpc_auth *auth, struct auth_cred *acred, int flags)
  56{
  57        return rpcauth_lookup_credcache(auth, acred, flags);
  58}
  59
  60static struct rpc_cred *
  61unx_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                        acred->uid, acred->gid);
  69
  70        if (!(cred = kmalloc(sizeof(*cred), GFP_NOFS)))
  71                return ERR_PTR(-ENOMEM);
  72
  73        rpcauth_init_cred(&cred->uc_base, acred, auth, &unix_credops);
  74        cred->uc_base.cr_flags = 1UL << RPCAUTH_CRED_UPTODATE;
  75
  76        if (acred->group_info != NULL)
  77                groups = acred->group_info->ngroups;
  78        if (groups > NFS_NGROUPS)
  79                groups = NFS_NGROUPS;
  80
  81        cred->uc_gid = acred->gid;
  82        for (i = 0; i < groups; i++) {
  83                gid_t gid;
  84                gid = from_kgid(&init_user_ns, GROUP_AT(acred->group_info, i));
  85                cred->uc_gids[i] = gid;
  86        }
  87        if (i < NFS_NGROUPS)
  88                cred->uc_gids[i] = NOGROUP;
  89
  90        return &cred->uc_base;
  91}
  92
  93static void
  94unx_free_cred(struct unx_cred *unx_cred)
  95{
  96        dprintk("RPC:       unx_free_cred %p\n", unx_cred);
  97        kfree(unx_cred);
  98}
  99
 100static void
 101unx_free_cred_callback(struct rcu_head *head)
 102{
 103        struct unx_cred *unx_cred = container_of(head, struct unx_cred, uc_base.cr_rcu);
 104        unx_free_cred(unx_cred);
 105}
 106
 107static void
 108unx_destroy_cred(struct rpc_cred *cred)
 109{
 110        call_rcu(&cred->cr_rcu, unx_free_cred_callback);
 111}
 112
 113/*
 114 * Match credentials against current process creds.
 115 * The root_override argument takes care of cases where the caller may
 116 * request root creds (e.g. for NFS swapping).
 117 */
 118static int
 119unx_match(struct auth_cred *acred, struct rpc_cred *rcred, int flags)
 120{
 121        struct unx_cred *cred = container_of(rcred, struct unx_cred, uc_base);
 122        unsigned int groups = 0;
 123        unsigned int i;
 124
 125
 126        if (cred->uc_uid != acred->uid || cred->uc_gid != acred->gid)
 127                return 0;
 128
 129        if (acred->group_info != NULL)
 130                groups = acred->group_info->ngroups;
 131        if (groups > NFS_NGROUPS)
 132                groups = NFS_NGROUPS;
 133        for (i = 0; i < groups ; i++) {
 134                gid_t gid;
 135                gid = from_kgid(&init_user_ns, GROUP_AT(acred->group_info, i));
 136                if (cred->uc_gids[i] != gid)
 137                        return 0;
 138        }
 139        if (groups < NFS_NGROUPS &&
 140            cred->uc_gids[groups] != NOGROUP)
 141                return 0;
 142        return 1;
 143}
 144
 145/*
 146 * Marshal credentials.
 147 * Maybe we should keep a cached credential for performance reasons.
 148 */
 149static __be32 *
 150unx_marshal(struct rpc_task *task, __be32 *p)
 151{
 152        struct rpc_clnt *clnt = task->tk_client;
 153        struct unx_cred *cred = container_of(task->tk_rqstp->rq_cred, struct unx_cred, uc_base);
 154        __be32          *base, *hold;
 155        int             i;
 156
 157        *p++ = htonl(RPC_AUTH_UNIX);
 158        base = p++;
 159        *p++ = htonl(jiffies/HZ);
 160
 161        /*
 162         * Copy the UTS nodename captured when the client was created.
 163         */
 164        p = xdr_encode_array(p, clnt->cl_nodename, clnt->cl_nodelen);
 165
 166        *p++ = htonl((u32) cred->uc_uid);
 167        *p++ = htonl((u32) cred->uc_gid);
 168        hold = p++;
 169        for (i = 0; i < 16 && cred->uc_gids[i] != (gid_t) NOGROUP; i++)
 170                *p++ = htonl((u32) cred->uc_gids[i]);
 171        *hold = htonl(p - hold - 1);            /* gid array length */
 172        *base = htonl((p - base - 1) << 2);     /* cred length */
 173
 174        *p++ = htonl(RPC_AUTH_NULL);
 175        *p++ = htonl(0);
 176
 177        return p;
 178}
 179
 180/*
 181 * Refresh credentials. This is a no-op for AUTH_UNIX
 182 */
 183static int
 184unx_refresh(struct rpc_task *task)
 185{
 186        set_bit(RPCAUTH_CRED_UPTODATE, &task->tk_rqstp->rq_cred->cr_flags);
 187        return 0;
 188}
 189
 190static __be32 *
 191unx_validate(struct rpc_task *task, __be32 *p)
 192{
 193        rpc_authflavor_t        flavor;
 194        u32                     size;
 195
 196        flavor = ntohl(*p++);
 197        if (flavor != RPC_AUTH_NULL &&
 198            flavor != RPC_AUTH_UNIX &&
 199            flavor != RPC_AUTH_SHORT) {
 200                printk("RPC: bad verf flavor: %u\n", flavor);
 201                return NULL;
 202        }
 203
 204        size = ntohl(*p++);
 205        if (size > RPC_MAX_AUTH_SIZE) {
 206                printk("RPC: giant verf size: %u\n", size);
 207                return NULL;
 208        }
 209        task->tk_rqstp->rq_cred->cr_auth->au_rslack = (size >> 2) + 2;
 210        p += (size >> 2);
 211
 212        return p;
 213}
 214
 215int __init rpc_init_authunix(void)
 216{
 217        return rpcauth_init_credcache(&unix_auth);
 218}
 219
 220void rpc_destroy_authunix(void)
 221{
 222        rpcauth_destroy_credcache(&unix_auth);
 223}
 224
 225const struct rpc_authops authunix_ops = {
 226        .owner          = THIS_MODULE,
 227        .au_flavor      = RPC_AUTH_UNIX,
 228        .au_name        = "UNIX",
 229        .create         = unx_create,
 230        .destroy        = unx_destroy,
 231        .lookup_cred    = unx_lookup_cred,
 232        .crcreate       = unx_create_cred,
 233};
 234
 235static
 236struct rpc_auth         unix_auth = {
 237        .au_cslack      = UNX_WRITESLACK,
 238        .au_rslack      = 2,                    /* assume AUTH_NULL verf */
 239        .au_ops         = &authunix_ops,
 240        .au_flavor      = RPC_AUTH_UNIX,
 241        .au_count       = ATOMIC_INIT(0),
 242};
 243
 244static
 245const 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};
 254
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