linux/fs/nfs/nfs3acl.c
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   1#include <linux/fs.h>
   2#include <linux/gfp.h>
   3#include <linux/nfs.h>
   4#include <linux/nfs3.h>
   5#include <linux/nfs_fs.h>
   6#include <linux/posix_acl_xattr.h>
   7#include <linux/nfsacl.h>
   8
   9#include "internal.h"
  10#include "nfs3_fs.h"
  11
  12#define NFSDBG_FACILITY NFSDBG_PROC
  13
  14/*
  15 * nfs3_prepare_get_acl, nfs3_complete_get_acl, nfs3_abort_get_acl: Helpers for
  16 * caching get_acl results in a race-free way.  See fs/posix_acl.c:get_acl()
  17 * for explanations.
  18 */
  19static void nfs3_prepare_get_acl(struct posix_acl **p)
  20{
  21        struct posix_acl *sentinel = uncached_acl_sentinel(current);
  22
  23        if (cmpxchg(p, ACL_NOT_CACHED, sentinel) != ACL_NOT_CACHED) {
  24                /* Not the first reader or sentinel already in place. */
  25        }
  26}
  27
  28static void nfs3_complete_get_acl(struct posix_acl **p, struct posix_acl *acl)
  29{
  30        struct posix_acl *sentinel = uncached_acl_sentinel(current);
  31
  32        /* Only cache the ACL if our sentinel is still in place. */
  33        posix_acl_dup(acl);
  34        if (cmpxchg(p, sentinel, acl) != sentinel)
  35                posix_acl_release(acl);
  36}
  37
  38static void nfs3_abort_get_acl(struct posix_acl **p)
  39{
  40        struct posix_acl *sentinel = uncached_acl_sentinel(current);
  41
  42        /* Remove our sentinel upon failure. */
  43        cmpxchg(p, sentinel, ACL_NOT_CACHED);
  44}
  45
  46struct posix_acl *nfs3_get_acl(struct inode *inode, int type)
  47{
  48        struct nfs_server *server = NFS_SERVER(inode);
  49        struct page *pages[NFSACL_MAXPAGES] = { };
  50        struct nfs3_getaclargs args = {
  51                .fh = NFS_FH(inode),
  52                /* The xdr layer may allocate pages here. */
  53                .pages = pages,
  54        };
  55        struct nfs3_getaclres res = {
  56                NULL,
  57        };
  58        struct rpc_message msg = {
  59                .rpc_argp       = &args,
  60                .rpc_resp       = &res,
  61        };
  62        int status, count;
  63
  64        if (!nfs_server_capable(inode, NFS_CAP_ACLS))
  65                return ERR_PTR(-EOPNOTSUPP);
  66
  67        status = nfs_revalidate_inode(server, inode);
  68        if (status < 0)
  69                return ERR_PTR(status);
  70
  71        /*
  72         * Only get the access acl when explicitly requested: We don't
  73         * need it for access decisions, and only some applications use
  74         * it. Applications which request the access acl first are not
  75         * penalized from this optimization.
  76         */
  77        if (type == ACL_TYPE_ACCESS)
  78                args.mask |= NFS_ACLCNT|NFS_ACL;
  79        if (S_ISDIR(inode->i_mode))
  80                args.mask |= NFS_DFACLCNT|NFS_DFACL;
  81        if (args.mask == 0)
  82                return NULL;
  83
  84        dprintk("NFS call getacl\n");
  85        msg.rpc_proc = &server->client_acl->cl_procinfo[ACLPROC3_GETACL];
  86        res.fattr = nfs_alloc_fattr();
  87        if (res.fattr == NULL)
  88                return ERR_PTR(-ENOMEM);
  89
  90        if (args.mask & NFS_ACL)
  91                nfs3_prepare_get_acl(&inode->i_acl);
  92        if (args.mask & NFS_DFACL)
  93                nfs3_prepare_get_acl(&inode->i_default_acl);
  94
  95        status = rpc_call_sync(server->client_acl, &msg, 0);
  96        dprintk("NFS reply getacl: %d\n", status);
  97
  98        /* pages may have been allocated at the xdr layer. */
  99        for (count = 0; count < NFSACL_MAXPAGES && args.pages[count]; count++)
 100                __free_page(args.pages[count]);
 101
 102        switch (status) {
 103                case 0:
 104                        status = nfs_refresh_inode(inode, res.fattr);
 105                        break;
 106                case -EPFNOSUPPORT:
 107                case -EPROTONOSUPPORT:
 108                        dprintk("NFS_V3_ACL extension not supported; disabling\n");
 109                        server->caps &= ~NFS_CAP_ACLS;
 110                case -ENOTSUPP:
 111                        status = -EOPNOTSUPP;
 112                default:
 113                        goto getout;
 114        }
 115        if ((args.mask & res.mask) != args.mask) {
 116                status = -EIO;
 117                goto getout;
 118        }
 119
 120        if (res.acl_access != NULL) {
 121                if ((posix_acl_equiv_mode(res.acl_access, NULL) == 0) ||
 122                    res.acl_access->a_count == 0) {
 123                        posix_acl_release(res.acl_access);
 124                        res.acl_access = NULL;
 125                }
 126        }
 127
 128        if (res.mask & NFS_ACL)
 129                nfs3_complete_get_acl(&inode->i_acl, res.acl_access);
 130        else
 131                forget_cached_acl(inode, ACL_TYPE_ACCESS);
 132
 133        if (res.mask & NFS_DFACL)
 134                nfs3_complete_get_acl(&inode->i_default_acl, res.acl_default);
 135        else
 136                forget_cached_acl(inode, ACL_TYPE_DEFAULT);
 137
 138        nfs_free_fattr(res.fattr);
 139        if (type == ACL_TYPE_ACCESS) {
 140                posix_acl_release(res.acl_default);
 141                return res.acl_access;
 142        } else {
 143                posix_acl_release(res.acl_access);
 144                return res.acl_default;
 145        }
 146
 147getout:
 148        nfs3_abort_get_acl(&inode->i_acl);
 149        nfs3_abort_get_acl(&inode->i_default_acl);
 150        posix_acl_release(res.acl_access);
 151        posix_acl_release(res.acl_default);
 152        nfs_free_fattr(res.fattr);
 153        return ERR_PTR(status);
 154}
 155
 156static int __nfs3_proc_setacls(struct inode *inode, struct posix_acl *acl,
 157                struct posix_acl *dfacl)
 158{
 159        struct nfs_server *server = NFS_SERVER(inode);
 160        struct nfs_fattr *fattr;
 161        struct page *pages[NFSACL_MAXPAGES];
 162        struct nfs3_setaclargs args = {
 163                .inode = inode,
 164                .mask = NFS_ACL,
 165                .acl_access = acl,
 166                .pages = pages,
 167        };
 168        struct rpc_message msg = {
 169                .rpc_argp       = &args,
 170                .rpc_resp       = &fattr,
 171        };
 172        int status = 0;
 173
 174        if (acl == NULL && (!S_ISDIR(inode->i_mode) || dfacl == NULL))
 175                goto out;
 176
 177        status = -EOPNOTSUPP;
 178        if (!nfs_server_capable(inode, NFS_CAP_ACLS))
 179                goto out;
 180
 181        /* We are doing this here because XDR marshalling does not
 182         * return any results, it BUGs. */
 183        status = -ENOSPC;
 184        if (acl != NULL && acl->a_count > NFS_ACL_MAX_ENTRIES)
 185                goto out;
 186        if (dfacl != NULL && dfacl->a_count > NFS_ACL_MAX_ENTRIES)
 187                goto out;
 188        if (S_ISDIR(inode->i_mode)) {
 189                args.mask |= NFS_DFACL;
 190                args.acl_default = dfacl;
 191                args.len = nfsacl_size(acl, dfacl);
 192        } else
 193                args.len = nfsacl_size(acl, NULL);
 194
 195        if (args.len > NFS_ACL_INLINE_BUFSIZE) {
 196                unsigned int npages = 1 + ((args.len - 1) >> PAGE_SHIFT);
 197
 198                status = -ENOMEM;
 199                do {
 200                        args.pages[args.npages] = alloc_page(GFP_KERNEL);
 201                        if (args.pages[args.npages] == NULL)
 202                                goto out_freepages;
 203                        args.npages++;
 204                } while (args.npages < npages);
 205        }
 206
 207        dprintk("NFS call setacl\n");
 208        status = -ENOMEM;
 209        fattr = nfs_alloc_fattr();
 210        if (fattr == NULL)
 211                goto out_freepages;
 212
 213        msg.rpc_proc = &server->client_acl->cl_procinfo[ACLPROC3_SETACL];
 214        msg.rpc_resp = fattr;
 215        status = rpc_call_sync(server->client_acl, &msg, 0);
 216        nfs_access_zap_cache(inode);
 217        nfs_zap_acl_cache(inode);
 218        dprintk("NFS reply setacl: %d\n", status);
 219
 220        switch (status) {
 221                case 0:
 222                        status = nfs_refresh_inode(inode, fattr);
 223                        set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
 224                        set_cached_acl(inode, ACL_TYPE_DEFAULT, dfacl);
 225                        break;
 226                case -EPFNOSUPPORT:
 227                case -EPROTONOSUPPORT:
 228                        dprintk("NFS_V3_ACL SETACL RPC not supported"
 229                                        "(will not retry)\n");
 230                        server->caps &= ~NFS_CAP_ACLS;
 231                case -ENOTSUPP:
 232                        status = -EOPNOTSUPP;
 233        }
 234        nfs_free_fattr(fattr);
 235out_freepages:
 236        while (args.npages != 0) {
 237                args.npages--;
 238                __free_page(args.pages[args.npages]);
 239        }
 240out:
 241        return status;
 242}
 243
 244int nfs3_proc_setacls(struct inode *inode, struct posix_acl *acl,
 245                struct posix_acl *dfacl)
 246{
 247        int ret;
 248        ret = __nfs3_proc_setacls(inode, acl, dfacl);
 249        return (ret == -EOPNOTSUPP) ? 0 : ret;
 250
 251}
 252
 253int nfs3_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 254{
 255        struct posix_acl *alloc = NULL, *dfacl = NULL;
 256        int status;
 257
 258        if (S_ISDIR(inode->i_mode)) {
 259                switch(type) {
 260                case ACL_TYPE_ACCESS:
 261                        alloc = dfacl = get_acl(inode, ACL_TYPE_DEFAULT);
 262                        if (IS_ERR(alloc))
 263                                goto fail;
 264                        break;
 265
 266                case ACL_TYPE_DEFAULT:
 267                        dfacl = acl;
 268                        alloc = acl = get_acl(inode, ACL_TYPE_ACCESS);
 269                        if (IS_ERR(alloc))
 270                                goto fail;
 271                        break;
 272                }
 273        }
 274
 275        if (acl == NULL) {
 276                alloc = acl = posix_acl_from_mode(inode->i_mode, GFP_KERNEL);
 277                if (IS_ERR(alloc))
 278                        goto fail;
 279        }
 280        status = __nfs3_proc_setacls(inode, acl, dfacl);
 281        posix_acl_release(alloc);
 282        return status;
 283
 284fail:
 285        return PTR_ERR(alloc);
 286}
 287
 288const struct xattr_handler *nfs3_xattr_handlers[] = {
 289        &posix_acl_access_xattr_handler,
 290        &posix_acl_default_xattr_handler,
 291        NULL,
 292};
 293
 294static int
 295nfs3_list_one_acl(struct inode *inode, int type, const char *name, void *data,
 296                size_t size, ssize_t *result)
 297{
 298        struct posix_acl *acl;
 299        char *p = data + *result;
 300
 301        acl = get_acl(inode, type);
 302        if (IS_ERR_OR_NULL(acl))
 303                return 0;
 304
 305        posix_acl_release(acl);
 306
 307        *result += strlen(name);
 308        *result += 1;
 309        if (!size)
 310                return 0;
 311        if (*result > size)
 312                return -ERANGE;
 313
 314        strcpy(p, name);
 315        return 0;
 316}
 317
 318ssize_t
 319nfs3_listxattr(struct dentry *dentry, char *data, size_t size)
 320{
 321        struct inode *inode = d_inode(dentry);
 322        ssize_t result = 0;
 323        int error;
 324
 325        error = nfs3_list_one_acl(inode, ACL_TYPE_ACCESS,
 326                        XATTR_NAME_POSIX_ACL_ACCESS, data, size, &result);
 327        if (error)
 328                return error;
 329
 330        error = nfs3_list_one_acl(inode, ACL_TYPE_DEFAULT,
 331                        XATTR_NAME_POSIX_ACL_DEFAULT, data, size, &result);
 332        if (error)
 333                return error;
 334        return result;
 335}
 336