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, 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
 153getout:
 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
 162static 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);
 240out_freepages:
 241        while (args.npages != 0) {
 242                args.npages--;
 243                __free_page(args.pages[args.npages]);
 244        }
 245out:
 246        return status;
 247}
 248
 249int 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
 258int nfs3_set_acl(struct user_namespace *mnt_userns, struct inode *inode,
 259                 struct posix_acl *acl, int type)
 260{
 261        struct posix_acl *orig = acl, *dfacl = NULL, *alloc;
 262        int status;
 263
 264        if (S_ISDIR(inode->i_mode)) {
 265                switch(type) {
 266                case ACL_TYPE_ACCESS:
 267                        alloc = get_acl(inode, ACL_TYPE_DEFAULT);
 268                        if (IS_ERR(alloc))
 269                                goto fail;
 270                        dfacl = alloc;
 271                        break;
 272
 273                case ACL_TYPE_DEFAULT:
 274                        alloc = get_acl(inode, ACL_TYPE_ACCESS);
 275                        if (IS_ERR(alloc))
 276                                goto fail;
 277                        dfacl = acl;
 278                        acl = alloc;
 279                        break;
 280                }
 281        }
 282
 283        if (acl == NULL) {
 284                alloc = posix_acl_from_mode(inode->i_mode, GFP_KERNEL);
 285                if (IS_ERR(alloc))
 286                        goto fail;
 287                acl = alloc;
 288        }
 289        status = __nfs3_proc_setacls(inode, acl, dfacl);
 290out:
 291        if (acl != orig)
 292                posix_acl_release(acl);
 293        if (dfacl != orig)
 294                posix_acl_release(dfacl);
 295        return status;
 296
 297fail:
 298        status = PTR_ERR(alloc);
 299        goto out;
 300}
 301
 302const struct xattr_handler *nfs3_xattr_handlers[] = {
 303        &posix_acl_access_xattr_handler,
 304        &posix_acl_default_xattr_handler,
 305        NULL,
 306};
 307
 308static int
 309nfs3_list_one_acl(struct inode *inode, int type, const char *name, void *data,
 310                size_t size, ssize_t *result)
 311{
 312        struct posix_acl *acl;
 313        char *p = data + *result;
 314
 315        acl = get_acl(inode, type);
 316        if (IS_ERR_OR_NULL(acl))
 317                return 0;
 318
 319        posix_acl_release(acl);
 320
 321        *result += strlen(name);
 322        *result += 1;
 323        if (!size)
 324                return 0;
 325        if (*result > size)
 326                return -ERANGE;
 327
 328        strcpy(p, name);
 329        return 0;
 330}
 331
 332ssize_t
 333nfs3_listxattr(struct dentry *dentry, char *data, size_t size)
 334{
 335        struct inode *inode = d_inode(dentry);
 336        ssize_t result = 0;
 337        int error;
 338
 339        error = nfs3_list_one_acl(inode, ACL_TYPE_ACCESS,
 340                        XATTR_NAME_POSIX_ACL_ACCESS, data, size, &result);
 341        if (error)
 342                return error;
 343
 344        error = nfs3_list_one_acl(inode, ACL_TYPE_DEFAULT,
 345                        XATTR_NAME_POSIX_ACL_DEFAULT, data, size, &result);
 346        if (error)
 347                return error;
 348        return result;
 349}
 350