linux/fs/nfs/nfs3acl.c
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   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 */
  20static 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
  29static 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
  39static 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
  47struct posix_acl *nfs3_get_acl(struct inode *inode, int type)
  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 (!nfs_server_capable(inode, NFS_CAP_ACLS))
  66                return ERR_PTR(-EOPNOTSUPP);
  67
  68        status = nfs_revalidate_inode(server, inode);
  69        if (status < 0)
  70                return ERR_PTR(status);
  71
  72        /*
  73         * Only get the access acl when explicitly requested: We don't
  74         * need it for access decisions, and only some applications use
  75         * it. Applications which request the access acl first are not
  76         * penalized from this optimization.
  77         */
  78        if (type == ACL_TYPE_ACCESS)
  79                args.mask |= NFS_ACLCNT|NFS_ACL;
  80        if (S_ISDIR(inode->i_mode))
  81                args.mask |= NFS_DFACLCNT|NFS_DFACL;
  82        if (args.mask == 0)
  83                return NULL;
  84
  85        dprintk("NFS call getacl\n");
  86        msg.rpc_proc = &server->client_acl->cl_procinfo[ACLPROC3_GETACL];
  87        res.fattr = nfs_alloc_fattr();
  88        if (res.fattr == NULL)
  89                return ERR_PTR(-ENOMEM);
  90
  91        if (args.mask & NFS_ACL)
  92                nfs3_prepare_get_acl(&inode->i_acl);
  93        if (args.mask & NFS_DFACL)
  94                nfs3_prepare_get_acl(&inode->i_default_acl);
  95
  96        status = rpc_call_sync(server->client_acl, &msg, 0);
  97        dprintk("NFS reply getacl: %d\n", status);
  98
  99        /* pages may have been allocated at the xdr layer. */
 100        for (count = 0; count < NFSACL_MAXPAGES && args.pages[count]; count++)
 101                __free_page(args.pages[count]);
 102
 103        switch (status) {
 104                case 0:
 105                        status = nfs_refresh_inode(inode, res.fattr);
 106                        break;
 107                case -EPFNOSUPPORT:
 108                case -EPROTONOSUPPORT:
 109                        dprintk("NFS_V3_ACL extension not supported; disabling\n");
 110                        server->caps &= ~NFS_CAP_ACLS;
 111                        /* fall through */
 112                case -ENOTSUPP:
 113                        status = -EOPNOTSUPP;
 114                default:
 115                        goto getout;
 116        }
 117        if ((args.mask & res.mask) != args.mask) {
 118                status = -EIO;
 119                goto getout;
 120        }
 121
 122        if (res.acl_access != NULL) {
 123                if ((posix_acl_equiv_mode(res.acl_access, NULL) == 0) ||
 124                    res.acl_access->a_count == 0) {
 125                        posix_acl_release(res.acl_access);
 126                        res.acl_access = NULL;
 127                }
 128        }
 129
 130        if (res.mask & NFS_ACL)
 131                nfs3_complete_get_acl(&inode->i_acl, res.acl_access);
 132        else
 133                forget_cached_acl(inode, ACL_TYPE_ACCESS);
 134
 135        if (res.mask & NFS_DFACL)
 136                nfs3_complete_get_acl(&inode->i_default_acl, res.acl_default);
 137        else
 138                forget_cached_acl(inode, ACL_TYPE_DEFAULT);
 139
 140        nfs_free_fattr(res.fattr);
 141        if (type == ACL_TYPE_ACCESS) {
 142                posix_acl_release(res.acl_default);
 143                return res.acl_access;
 144        } else {
 145                posix_acl_release(res.acl_access);
 146                return res.acl_default;
 147        }
 148
 149getout:
 150        nfs3_abort_get_acl(&inode->i_acl);
 151        nfs3_abort_get_acl(&inode->i_default_acl);
 152        posix_acl_release(res.acl_access);
 153        posix_acl_release(res.acl_default);
 154        nfs_free_fattr(res.fattr);
 155        return ERR_PTR(status);
 156}
 157
 158static int __nfs3_proc_setacls(struct inode *inode, struct posix_acl *acl,
 159                struct posix_acl *dfacl)
 160{
 161        struct nfs_server *server = NFS_SERVER(inode);
 162        struct nfs_fattr *fattr;
 163        struct page *pages[NFSACL_MAXPAGES];
 164        struct nfs3_setaclargs args = {
 165                .inode = inode,
 166                .mask = NFS_ACL,
 167                .acl_access = acl,
 168                .pages = pages,
 169        };
 170        struct rpc_message msg = {
 171                .rpc_argp       = &args,
 172                .rpc_resp       = &fattr,
 173        };
 174        int status = 0;
 175
 176        if (acl == NULL && (!S_ISDIR(inode->i_mode) || dfacl == NULL))
 177                goto out;
 178
 179        status = -EOPNOTSUPP;
 180        if (!nfs_server_capable(inode, NFS_CAP_ACLS))
 181                goto out;
 182
 183        /* We are doing this here because XDR marshalling does not
 184         * return any results, it BUGs. */
 185        status = -ENOSPC;
 186        if (acl != NULL && acl->a_count > NFS_ACL_MAX_ENTRIES)
 187                goto out;
 188        if (dfacl != NULL && dfacl->a_count > NFS_ACL_MAX_ENTRIES)
 189                goto out;
 190        if (S_ISDIR(inode->i_mode)) {
 191                args.mask |= NFS_DFACL;
 192                args.acl_default = dfacl;
 193                args.len = nfsacl_size(acl, dfacl);
 194        } else
 195                args.len = nfsacl_size(acl, NULL);
 196
 197        if (args.len > NFS_ACL_INLINE_BUFSIZE) {
 198                unsigned int npages = 1 + ((args.len - 1) >> PAGE_SHIFT);
 199
 200                status = -ENOMEM;
 201                do {
 202                        args.pages[args.npages] = alloc_page(GFP_KERNEL);
 203                        if (args.pages[args.npages] == NULL)
 204                                goto out_freepages;
 205                        args.npages++;
 206                } while (args.npages < npages);
 207        }
 208
 209        dprintk("NFS call setacl\n");
 210        status = -ENOMEM;
 211        fattr = nfs_alloc_fattr();
 212        if (fattr == NULL)
 213                goto out_freepages;
 214
 215        msg.rpc_proc = &server->client_acl->cl_procinfo[ACLPROC3_SETACL];
 216        msg.rpc_resp = fattr;
 217        status = rpc_call_sync(server->client_acl, &msg, 0);
 218        nfs_access_zap_cache(inode);
 219        nfs_zap_acl_cache(inode);
 220        dprintk("NFS reply setacl: %d\n", status);
 221
 222        switch (status) {
 223                case 0:
 224                        status = nfs_refresh_inode(inode, fattr);
 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                        /* fall through */
 232                case -ENOTSUPP:
 233                        status = -EOPNOTSUPP;
 234        }
 235        nfs_free_fattr(fattr);
 236out_freepages:
 237        while (args.npages != 0) {
 238                args.npages--;
 239                __free_page(args.pages[args.npages]);
 240        }
 241out:
 242        return status;
 243}
 244
 245int nfs3_proc_setacls(struct inode *inode, struct posix_acl *acl,
 246                struct posix_acl *dfacl)
 247{
 248        int ret;
 249        ret = __nfs3_proc_setacls(inode, acl, dfacl);
 250        return (ret == -EOPNOTSUPP) ? 0 : ret;
 251
 252}
 253
 254int nfs3_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 255{
 256        struct posix_acl *orig = acl, *dfacl = NULL, *alloc;
 257        int status;
 258
 259        if (S_ISDIR(inode->i_mode)) {
 260                switch(type) {
 261                case ACL_TYPE_ACCESS:
 262                        alloc = get_acl(inode, ACL_TYPE_DEFAULT);
 263                        if (IS_ERR(alloc))
 264                                goto fail;
 265                        dfacl = alloc;
 266                        break;
 267
 268                case ACL_TYPE_DEFAULT:
 269                        alloc = get_acl(inode, ACL_TYPE_ACCESS);
 270                        if (IS_ERR(alloc))
 271                                goto fail;
 272                        dfacl = acl;
 273                        acl = alloc;
 274                        break;
 275                }
 276        }
 277
 278        if (acl == NULL) {
 279                alloc = posix_acl_from_mode(inode->i_mode, GFP_KERNEL);
 280                if (IS_ERR(alloc))
 281                        goto fail;
 282                acl = alloc;
 283        }
 284        status = __nfs3_proc_setacls(inode, acl, dfacl);
 285out:
 286        if (acl != orig)
 287                posix_acl_release(acl);
 288        if (dfacl != orig)
 289                posix_acl_release(dfacl);
 290        return status;
 291
 292fail:
 293        status = PTR_ERR(alloc);
 294        goto out;
 295}
 296
 297const struct xattr_handler *nfs3_xattr_handlers[] = {
 298        &posix_acl_access_xattr_handler,
 299        &posix_acl_default_xattr_handler,
 300        NULL,
 301};
 302
 303static int
 304nfs3_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_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
 327ssize_t
 328nfs3_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}
 345