linux/fs/nfs/nfs3acl.c
<<
>>
Prefs
   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(inode, NFS_INO_INVALID_CHANGE);
  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                        fallthrough;
 112                case -ENOTSUPP:
 113                        status = -EOPNOTSUPP;
 114                        goto getout;
 115                default:
 116                        goto getout;
 117        }
 118        if ((args.mask & res.mask) != args.mask) {
 119                status = -EIO;
 120                goto getout;
 121        }
 122
 123        if (res.acl_access != NULL) {
 124                if ((posix_acl_equiv_mode(res.acl_access, NULL) == 0) ||
 125                    res.acl_access->a_count == 0) {
 126                        posix_acl_release(res.acl_access);
 127                        res.acl_access = NULL;
 128                }
 129        }
 130
 131        if (res.mask & NFS_ACL)
 132                nfs3_complete_get_acl(&inode->i_acl, res.acl_access);
 133        else
 134                forget_cached_acl(inode, ACL_TYPE_ACCESS);
 135
 136        if (res.mask & NFS_DFACL)
 137                nfs3_complete_get_acl(&inode->i_default_acl, res.acl_default);
 138        else
 139                forget_cached_acl(inode, ACL_TYPE_DEFAULT);
 140
 141        nfs_free_fattr(res.fattr);
 142        if (type == ACL_TYPE_ACCESS) {
 143                posix_acl_release(res.acl_default);
 144                return res.acl_access;
 145        } else {
 146                posix_acl_release(res.acl_access);
 147                return res.acl_default;
 148        }
 149
 150getout:
 151        nfs3_abort_get_acl(&inode->i_acl);
 152        nfs3_abort_get_acl(&inode->i_default_acl);
 153        posix_acl_release(res.acl_access);
 154        posix_acl_release(res.acl_default);
 155        nfs_free_fattr(res.fattr);
 156        return ERR_PTR(status);
 157}
 158
 159static int __nfs3_proc_setacls(struct inode *inode, struct posix_acl *acl,
 160                struct posix_acl *dfacl)
 161{
 162        struct nfs_server *server = NFS_SERVER(inode);
 163        struct nfs_fattr *fattr;
 164        struct page *pages[NFSACL_MAXPAGES];
 165        struct nfs3_setaclargs args = {
 166                .inode = inode,
 167                .mask = NFS_ACL,
 168                .acl_access = acl,
 169                .pages = pages,
 170        };
 171        struct rpc_message msg = {
 172                .rpc_argp       = &args,
 173                .rpc_resp       = &fattr,
 174        };
 175        int status = 0;
 176
 177        if (acl == NULL && (!S_ISDIR(inode->i_mode) || dfacl == NULL))
 178                goto out;
 179
 180        status = -EOPNOTSUPP;
 181        if (!nfs_server_capable(inode, NFS_CAP_ACLS))
 182                goto out;
 183
 184        /* We are doing this here because XDR marshalling does not
 185         * return any results, it BUGs. */
 186        status = -ENOSPC;
 187        if (acl != NULL && acl->a_count > NFS_ACL_MAX_ENTRIES)
 188                goto out;
 189        if (dfacl != NULL && dfacl->a_count > NFS_ACL_MAX_ENTRIES)
 190                goto out;
 191        if (S_ISDIR(inode->i_mode)) {
 192                args.mask |= NFS_DFACL;
 193                args.acl_default = dfacl;
 194                args.len = nfsacl_size(acl, dfacl);
 195        } else
 196                args.len = nfsacl_size(acl, NULL);
 197
 198        if (args.len > NFS_ACL_INLINE_BUFSIZE) {
 199                unsigned int npages = 1 + ((args.len - 1) >> PAGE_SHIFT);
 200
 201                status = -ENOMEM;
 202                do {
 203                        args.pages[args.npages] = alloc_page(GFP_KERNEL);
 204                        if (args.pages[args.npages] == NULL)
 205                                goto out_freepages;
 206                        args.npages++;
 207                } while (args.npages < npages);
 208        }
 209
 210        dprintk("NFS call setacl\n");
 211        status = -ENOMEM;
 212        fattr = nfs_alloc_fattr();
 213        if (fattr == NULL)
 214                goto out_freepages;
 215
 216        msg.rpc_proc = &server->client_acl->cl_procinfo[ACLPROC3_SETACL];
 217        msg.rpc_resp = fattr;
 218        status = rpc_call_sync(server->client_acl, &msg, 0);
 219        nfs_access_zap_cache(inode);
 220        nfs_zap_acl_cache(inode);
 221        dprintk("NFS reply setacl: %d\n", status);
 222
 223        switch (status) {
 224                case 0:
 225                        status = nfs_refresh_inode(inode, fattr);
 226                        break;
 227                case -EPFNOSUPPORT:
 228                case -EPROTONOSUPPORT:
 229                        dprintk("NFS_V3_ACL SETACL RPC not supported"
 230                                        "(will not retry)\n");
 231                        server->caps &= ~NFS_CAP_ACLS;
 232                        fallthrough;
 233                case -ENOTSUPP:
 234                        status = -EOPNOTSUPP;
 235        }
 236        nfs_free_fattr(fattr);
 237out_freepages:
 238        while (args.npages != 0) {
 239                args.npages--;
 240                __free_page(args.pages[args.npages]);
 241        }
 242out:
 243        return status;
 244}
 245
 246int nfs3_proc_setacls(struct inode *inode, struct posix_acl *acl,
 247                struct posix_acl *dfacl)
 248{
 249        int ret;
 250        ret = __nfs3_proc_setacls(inode, acl, dfacl);
 251        return (ret == -EOPNOTSUPP) ? 0 : ret;
 252
 253}
 254
 255int nfs3_set_acl(struct user_namespace *mnt_userns, struct inode *inode,
 256                 struct posix_acl *acl, int type)
 257{
 258        struct posix_acl *orig = acl, *dfacl = NULL, *alloc;
 259        int status;
 260
 261        if (S_ISDIR(inode->i_mode)) {
 262                switch(type) {
 263                case ACL_TYPE_ACCESS:
 264                        alloc = get_acl(inode, ACL_TYPE_DEFAULT);
 265                        if (IS_ERR(alloc))
 266                                goto fail;
 267                        dfacl = alloc;
 268                        break;
 269
 270                case ACL_TYPE_DEFAULT:
 271                        alloc = get_acl(inode, ACL_TYPE_ACCESS);
 272                        if (IS_ERR(alloc))
 273                                goto fail;
 274                        dfacl = acl;
 275                        acl = alloc;
 276                        break;
 277                }
 278        }
 279
 280        if (acl == NULL) {
 281                alloc = posix_acl_from_mode(inode->i_mode, GFP_KERNEL);
 282                if (IS_ERR(alloc))
 283                        goto fail;
 284                acl = alloc;
 285        }
 286        status = __nfs3_proc_setacls(inode, acl, dfacl);
 287out:
 288        if (acl != orig)
 289                posix_acl_release(acl);
 290        if (dfacl != orig)
 291                posix_acl_release(dfacl);
 292        return status;
 293
 294fail:
 295        status = PTR_ERR(alloc);
 296        goto out;
 297}
 298
 299const struct xattr_handler *nfs3_xattr_handlers[] = {
 300        &posix_acl_access_xattr_handler,
 301        &posix_acl_default_xattr_handler,
 302        NULL,
 303};
 304
 305static int
 306nfs3_list_one_acl(struct inode *inode, int type, const char *name, void *data,
 307                size_t size, ssize_t *result)
 308{
 309        struct posix_acl *acl;
 310        char *p = data + *result;
 311
 312        acl = get_acl(inode, type);
 313        if (IS_ERR_OR_NULL(acl))
 314                return 0;
 315
 316        posix_acl_release(acl);
 317
 318        *result += strlen(name);
 319        *result += 1;
 320        if (!size)
 321                return 0;
 322        if (*result > size)
 323                return -ERANGE;
 324
 325        strcpy(p, name);
 326        return 0;
 327}
 328
 329ssize_t
 330nfs3_listxattr(struct dentry *dentry, char *data, size_t size)
 331{
 332        struct inode *inode = d_inode(dentry);
 333        ssize_t result = 0;
 334        int error;
 335
 336        error = nfs3_list_one_acl(inode, ACL_TYPE_ACCESS,
 337                        XATTR_NAME_POSIX_ACL_ACCESS, data, size, &result);
 338        if (error)
 339                return error;
 340
 341        error = nfs3_list_one_acl(inode, ACL_TYPE_DEFAULT,
 342                        XATTR_NAME_POSIX_ACL_DEFAULT, data, size, &result);
 343        if (error)
 344                return error;
 345        return result;
 346}
 347