fs/nfs/nfs3acl.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/fs.h>
   3 #include <linux/gfp.h>
   4 #include <linux/nfs.h>
   5 #include <linux/nfs3.h>
   6 #include <linux/nfs_fs.h>
   7 #include <linux/posix_acl_xattr.h>
   8 #include <linux/nfsacl.h>
   9
  10 #include "internal.h"
  11 #include "nfs3_fs.h"
  12
  13 #define NFSDBG_FACILITY NFSDBG_PROC
  14
  15 /*
  16  * nfs3_prepare_get_acl, nfs3_complete_get_acl, nfs3_abort_get_acl: Helpers for
  17  * caching get_acl results in a race-free way.  See fs/posix_acl.c:get_acl()
  18  * for explanations.
  19  */
  20 static void nfs3_prepare_get_acl(struct posix_acl **p)
  21 {
  22         struct posix_acl *sentinel = uncached_acl_sentinel(current);
  23
  24         if (cmpxchg(p, ACL_NOT_CACHED, sentinel) != ACL_NOT_CACHED) {
  25                 /* Not the first reader or sentinel already in place. */
  26         }
  27 }
  28
  29 static void nfs3_complete_get_acl(struct posix_acl **p, struct posix_acl *acl)
  30 {
  31         struct posix_acl *sentinel = uncached_acl_sentinel(current);
  32
  33         /* Only cache the ACL if our sentinel is still in place. */
  34         posix_acl_dup(acl);
  35         if (cmpxchg(p, sentinel, acl) != sentinel)
  36                 posix_acl_release(acl);
  37 }
  38
  39 static void nfs3_abort_get_acl(struct posix_acl **p)
  40 {
  41         struct posix_acl *sentinel = uncached_acl_sentinel(current);
  42
  43         /* Remove our sentinel upon failure. */
  44         cmpxchg(p, sentinel, ACL_NOT_CACHED);
  45 }
  46
  47 struct posix_acl *nfs3_get_acl(struct inode *inode, int type, bool rcu)
  48 {
  49         struct nfs_server *server = NFS_SERVER(inode);
  50         struct page *pages[NFSACL_MAXPAGES] = { };
  51         struct nfs3_getaclargs args = {
  52                 .fh = NFS_FH(inode),
  53                 /* The xdr layer may allocate pages here. */
  54                 .pages = pages,
  55         };
  56         struct nfs3_getaclres res = {
  57                 NULL,
  58         };
  59         struct rpc_message msg = {
  60                 .rpc_argp       = &args,
  61                 .rpc_resp       = &res,
  62         };
  63         int status, count;
  64
  65         if (rcu)
  66                 return ERR_PTR(-ECHILD);
  67
  68         if (!nfs_server_capable(inode, NFS_CAP_ACLS))
  69                 return ERR_PTR(-EOPNOTSUPP);
  70
  71         status = nfs_revalidate_inode(inode, NFS_INO_INVALID_CHANGE);
  72         if (status < 0)
  73                 return ERR_PTR(status);
  74
  75         /*
  76          * Only get the access acl when explicitly requested: We don't
  77          * need it for access decisions, and only some applications use
  78          * it. Applications which request the access acl first are not
  79          * penalized from this optimization.
  80          */
  81         if (type == ACL_TYPE_ACCESS)
  82                 args.mask |= NFS_ACLCNT|NFS_ACL;
  83         if (S_ISDIR(inode->i_mode))
  84                 args.mask |= NFS_DFACLCNT|NFS_DFACL;
  85         if (args.mask == 0)
  86                 return NULL;
  87
  88         dprintk("NFS call getacl\n");
  89         msg.rpc_proc = &server->client_acl->cl_procinfo[ACLPROC3_GETACL];
  90         res.fattr = nfs_alloc_fattr();
  91         if (res.fattr == NULL)
  92                 return ERR_PTR(-ENOMEM);
  93
  94         if (args.mask & NFS_ACL)
  95                 nfs3_prepare_get_acl(&inode->i_acl);
  96         if (args.mask & NFS_DFACL)
  97                 nfs3_prepare_get_acl(&inode->i_default_acl);
  98
  99         status = rpc_call_sync(server->client_acl, &msg, 0);
 100         dprintk("NFS reply getacl: %d\n", status);
 101
 102         /* pages may have been allocated at the xdr layer. */
 103         for (count = 0; count < NFSACL_MAXPAGES && args.pages[count]; count++)
 104                 __free_page(args.pages[count]);
 105
 106         switch (status) {
 107                 case 0:
 108                         status = nfs_refresh_inode(inode, res.fattr);
 109                         break;
 110                 case -EPFNOSUPPORT:
 111                 case -EPROTONOSUPPORT:
 112                         dprintk("NFS_V3_ACL extension not supported; disabling\n");
 113                         server->caps &= ~NFS_CAP_ACLS;
 114                         fallthrough;
 115                 case -ENOTSUPP:
 116                         status = -EOPNOTSUPP;
 117                         goto getout;
 118                 default:
 119                         goto getout;
 120         }
 121         if ((args.mask & res.mask) != args.mask) {
 122                 status = -EIO;
 123                 goto getout;
 124         }
 125
 126         if (res.acl_access != NULL) {
 127                 if ((posix_acl_equiv_mode(res.acl_access, NULL) == 0) ||
 128                     res.acl_access->a_count == 0) {
 129                         posix_acl_release(res.acl_access);
 130                         res.acl_access = NULL;
 131                 }
 132         }
 133
 134         if (res.mask & NFS_ACL)
 135                 nfs3_complete_get_acl(&inode->i_acl, res.acl_access);
 136         else
 137                 forget_cached_acl(inode, ACL_TYPE_ACCESS);
 138
 139         if (res.mask & NFS_DFACL)
 140                 nfs3_complete_get_acl(&inode->i_default_acl, res.acl_default);
 141         else
 142                 forget_cached_acl(inode, ACL_TYPE_DEFAULT);
 143
 144         nfs_free_fattr(res.fattr);
 145         if (type == ACL_TYPE_ACCESS) {
 146                 posix_acl_release(res.acl_default);
 147                 return res.acl_access;
 148         } else {
 149                 posix_acl_release(res.acl_access);
 150                 return res.acl_default;
 151         }
 152
 153 getout:
 154         nfs3_abort_get_acl(&inode->i_acl);
 155         nfs3_abort_get_acl(&inode->i_default_acl);
 156         posix_acl_release(res.acl_access);
 157         posix_acl_release(res.acl_default);
 158         nfs_free_fattr(res.fattr);
 159         return ERR_PTR(status);
 160 }
 161
 162 static int __nfs3_proc_setacls(struct inode *inode, struct posix_acl *acl,
 163                 struct posix_acl *dfacl)
 164 {
 165         struct nfs_server *server = NFS_SERVER(inode);
 166         struct nfs_fattr *fattr;
 167         struct page *pages[NFSACL_MAXPAGES];
 168         struct nfs3_setaclargs args = {
 169                 .inode = inode,
 170                 .mask = NFS_ACL,
 171                 .acl_access = acl,
 172                 .pages = pages,
 173         };
 174         struct rpc_message msg = {
 175                 .rpc_argp       = &args,
 176                 .rpc_resp       = &fattr,
 177         };
 178         int status = 0;
 179
 180         if (acl == NULL && (!S_ISDIR(inode->i_mode) || dfacl == NULL))
 181                 goto out;
 182
 183         status = -EOPNOTSUPP;
 184         if (!nfs_server_capable(inode, NFS_CAP_ACLS))
 185                 goto out;
 186
 187         /* We are doing this here because XDR marshalling does not
 188          * return any results, it BUGs. */
 189         status = -ENOSPC;
 190         if (acl != NULL && acl->a_count > NFS_ACL_MAX_ENTRIES)
 191                 goto out;
 192         if (dfacl != NULL && dfacl->a_count > NFS_ACL_MAX_ENTRIES)
 193                 goto out;
 194         if (S_ISDIR(inode->i_mode)) {
 195                 args.mask |= NFS_DFACL;
 196                 args.acl_default = dfacl;
 197                 args.len = nfsacl_size(acl, dfacl);
 198         } else
 199                 args.len = nfsacl_size(acl, NULL);
 200
 201         if (args.len > NFS_ACL_INLINE_BUFSIZE) {
 202                 unsigned int npages = 1 + ((args.len - 1) >> PAGE_SHIFT);
 203
 204                 status = -ENOMEM;
 205                 do {
 206                         args.pages[args.npages] = alloc_page(GFP_KERNEL);
 207                         if (args.pages[args.npages] == NULL)
 208                                 goto out_freepages;
 209                         args.npages++;
 210                 } while (args.npages < npages);
 211         }
 212
 213         dprintk("NFS call setacl\n");
 214         status = -ENOMEM;
 215         fattr = nfs_alloc_fattr();
 216         if (fattr == NULL)
 217                 goto out_freepages;
 218
 219         msg.rpc_proc = &server->client_acl->cl_procinfo[ACLPROC3_SETACL];
 220         msg.rpc_resp = fattr;
 221         status = rpc_call_sync(server->client_acl, &msg, 0);
 222         nfs_access_zap_cache(inode);
 223         nfs_zap_acl_cache(inode);
 224         dprintk("NFS reply setacl: %d\n", status);
 225
 226         switch (status) {
 227                 case 0:
 228                         status = nfs_refresh_inode(inode, fattr);
 229                         break;
 230                 case -EPFNOSUPPORT:
 231                 case -EPROTONOSUPPORT:
 232                         dprintk("NFS_V3_ACL SETACL RPC not supported"
 233                                         "(will not retry)\n");
 234                         server->caps &= ~NFS_CAP_ACLS;
 235                         fallthrough;
 236                 case -ENOTSUPP:
 237                         status = -EOPNOTSUPP;
 238         }
 239         nfs_free_fattr(fattr);
 240 out_freepages:
 241         while (args.npages != 0) {
 242                 args.npages--;
 243                 __free_page(args.pages[args.npages]);
 244         }
 245 out:
 246         return status;
 247 }
 248
 249 int nfs3_proc_setacls(struct inode *inode, struct posix_acl *acl,
 250                 struct posix_acl *dfacl)
 251 {
 252         int ret;
 253         ret = __nfs3_proc_setacls(inode, acl, dfacl);
 254         return (ret == -EOPNOTSUPP) ? 0 : ret;
 255
 256 }
 257
 258 int nfs3_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
 259                  struct posix_acl *acl, int type)
 260 {
 261         struct posix_acl *orig = acl, *dfacl = NULL, *alloc;
 262         struct inode *inode = d_inode(dentry);
 263         int status;
 264
 265         if (S_ISDIR(inode->i_mode)) {
 266                 switch(type) {
 267                 case ACL_TYPE_ACCESS:
 268                         alloc = get_inode_acl(inode, ACL_TYPE_DEFAULT);
 269                         if (IS_ERR(alloc))
 270                                 goto fail;
 271                         dfacl = alloc;
 272                         break;
 273
 274                 case ACL_TYPE_DEFAULT:
 275                         alloc = get_inode_acl(inode, ACL_TYPE_ACCESS);
 276                         if (IS_ERR(alloc))
 277                                 goto fail;
 278                         dfacl = acl;
 279                         acl = alloc;
 280                         break;
 281                 }
 282         }
 283
 284         if (acl == NULL) {
 285                 alloc = posix_acl_from_mode(inode->i_mode, GFP_KERNEL);
 286                 if (IS_ERR(alloc))
 287                         goto fail;
 288                 acl = alloc;
 289         }
 290         status = __nfs3_proc_setacls(inode, acl, dfacl);
 291 out:
 292         if (acl != orig)
 293                 posix_acl_release(acl);
 294         if (dfacl != orig)
 295                 posix_acl_release(dfacl);
 296         return status;
 297
 298 fail:
 299         status = PTR_ERR(alloc);
 300         goto out;
 301 }
 302
 303 static int
 304 nfs3_list_one_acl(struct inode *inode, int type, const char *name, void *data,
 305                 size_t size, ssize_t *result)
 306 {
 307         struct posix_acl *acl;
 308         char *p = data + *result;
 309
 310         acl = get_inode_acl(inode, type);
 311         if (IS_ERR_OR_NULL(acl))
 312                 return 0;
 313
 314         posix_acl_release(acl);
 315
 316         *result += strlen(name);
 317         *result += 1;
 318         if (!size)
 319                 return 0;
 320         if (*result > size)
 321                 return -ERANGE;
 322
 323         strcpy(p, name);
 324         return 0;
 325 }
 326
 327 ssize_t
 328 nfs3_listxattr(struct dentry *dentry, char *data, size_t size)
 329 {
 330         struct inode *inode = d_inode(dentry);
 331         ssize_t result = 0;
 332         int error;
 333
 334         error = nfs3_list_one_acl(inode, ACL_TYPE_ACCESS,
 335                         XATTR_NAME_POSIX_ACL_ACCESS, data, size, &result);
 336         if (error)
 337                 return error;
 338
 339         error = nfs3_list_one_acl(inode, ACL_TYPE_DEFAULT,
 340                         XATTR_NAME_POSIX_ACL_DEFAULT, data, size, &result);
 341         if (error)
 342                 return error;
 343         return result;
 344 }