fs/cifs/cifsacl.c

   1 /*
   2  *   fs/cifs/cifsacl.c
   3  *
   4  *   Copyright (C) International Business Machines  Corp., 2007
   5  *   Author(s): Steve French (sfrench@us.ibm.com)
   6  *
   7  *   Contains the routines for mapping CIFS/NTFS ACLs
   8  *
   9  *   This library is free software; you can redistribute it and/or modify
  10  *   it under the terms of the GNU Lesser General Public License as published
  11  *   by the Free Software Foundation; either version 2.1 of the License, or
  12  *   (at your option) any later version.
  13  *
  14  *   This library is distributed in the hope that it will be useful,
  15  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
  17  *   the GNU Lesser General Public License for more details.
  18  *
  19  *   You should have received a copy of the GNU Lesser General Public License
  20  *   along with this library; if not, write to the Free Software
  21  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  22  */
  23
  24 #include <linux/fs.h>
  25 #include "cifspdu.h"
  26 #include "cifsglob.h"
  27 #include "cifsacl.h"
  28 #include "cifsproto.h"
  29 #include "cifs_debug.h"
  30
  31
  32 #ifdef CONFIG_CIFS_EXPERIMENTAL
  33
  34 static struct cifs_wksid wksidarr[NUM_WK_SIDS] = {
  35         {{1, 0, {0, 0, 0, 0, 0, 0}, {0, 0, 0, 0, 0} }, "null user"},
  36         {{1, 1, {0, 0, 0, 0, 0, 1}, {0, 0, 0, 0, 0} }, "nobody"},
  37         {{1, 1, {0, 0, 0, 0, 0, 5}, {cpu_to_le32(11), 0, 0, 0, 0} }, "net-users"},
  38         {{1, 1, {0, 0, 0, 0, 0, 5}, {cpu_to_le32(18), 0, 0, 0, 0} }, "sys"},
  39         {{1, 2, {0, 0, 0, 0, 0, 5}, {cpu_to_le32(32), cpu_to_le32(544), 0, 0, 0} }, "root"},
  40         {{1, 2, {0, 0, 0, 0, 0, 5}, {cpu_to_le32(32), cpu_to_le32(545), 0, 0, 0} }, "users"},
  41         {{1, 2, {0, 0, 0, 0, 0, 5}, {cpu_to_le32(32), cpu_to_le32(546), 0, 0, 0} }, "guest"} }
  42 ;
  43
  44
  45 /* security id for everyone */
  46 static const struct cifs_sid sid_everyone = {
  47         1, 1, {0, 0, 0, 0, 0, 1}, {0} };
  48 /* group users */
  49 static const struct cifs_sid sid_user =
  50                 {1, 2 , {0, 0, 0, 0, 0, 5}, {} };
  51
  52
  53 int match_sid(struct cifs_sid *ctsid)
  54 {
  55         int i, j;
  56         int num_subauth, num_sat, num_saw;
  57         struct cifs_sid *cwsid;
  58
  59         if (!ctsid)
  60                 return (-1);
  61
  62         for (i = 0; i < NUM_WK_SIDS; ++i) {
  63                 cwsid = &(wksidarr[i].cifssid);
  64
  65                 /* compare the revision */
  66                 if (ctsid->revision != cwsid->revision)
  67                         continue;
  68
  69                 /* compare all of the six auth values */
  70                 for (j = 0; j < 6; ++j) {
  71                         if (ctsid->authority[j] != cwsid->authority[j])
  72                                 break;
  73                 }
  74                 if (j < 6)
  75                         continue; /* all of the auth values did not match */
  76
  77                 /* compare all of the subauth values if any */
  78                 num_sat = ctsid->num_subauth;
  79                 num_saw = cwsid->num_subauth;
  80                 num_subauth = num_sat < num_saw ? num_sat : num_saw;
  81                 if (num_subauth) {
  82                         for (j = 0; j < num_subauth; ++j) {
  83                                 if (ctsid->sub_auth[j] != cwsid->sub_auth[j])
  84                                         break;
  85                         }
  86                         if (j < num_subauth)
  87                                 continue; /* all sub_auth values do not match */
  88                 }
  89
  90                 cFYI(1, ("matching sid: %s\n", wksidarr[i].sidname));
  91                 return (0); /* sids compare/match */
  92         }
  93
  94         cFYI(1, ("No matching sid"));
  95         return (-1);
  96 }
  97
  98 /* if the two SIDs (roughly equivalent to a UUID for a user or group) are
  99    the same returns 1, if they do not match returns 0 */
 100 int compare_sids(const struct cifs_sid *ctsid, const struct cifs_sid *cwsid)
 101 {
 102         int i;
 103         int num_subauth, num_sat, num_saw;
 104
 105         if ((!ctsid) || (!cwsid))
 106                 return (0);
 107
 108         /* compare the revision */
 109         if (ctsid->revision != cwsid->revision)
 110                 return (0);
 111
 112         /* compare all of the six auth values */
 113         for (i = 0; i < 6; ++i) {
 114                 if (ctsid->authority[i] != cwsid->authority[i])
 115                         return (0);
 116         }
 117
 118         /* compare all of the subauth values if any */
 119         num_sat = ctsid->num_subauth;
 120         num_saw = cwsid->num_subauth;
 121         num_subauth = num_sat < num_saw ? num_sat : num_saw;
 122         if (num_subauth) {
 123                 for (i = 0; i < num_subauth; ++i) {
 124                         if (ctsid->sub_auth[i] != cwsid->sub_auth[i])
 125                                 return (0);
 126                 }
 127         }
 128
 129         return (1); /* sids compare/match */
 130 }
 131
 132 /*
 133    change posix mode to reflect permissions
 134    pmode is the existing mode (we only want to overwrite part of this
 135    bits to set can be: S_IRWXU, S_IRWXG or S_IRWXO ie 00700 or 00070 or 00007
 136 */
 137 static void access_flags_to_mode(__le32 ace_flags, int type, umode_t *pmode,
 138                                  umode_t *pbits_to_set)
 139 {
 140         __u32 flags = le32_to_cpu(ace_flags);
 141         /* the order of ACEs is important.  The canonical order is to begin with
 142            DENY entries followed by ALLOW, otherwise an allow entry could be
 143            encountered first, making the subsequent deny entry like "dead code"
 144            which would be superflous since Windows stops when a match is made
 145            for the operation you are trying to perform for your user */
 146
 147         /* For deny ACEs we change the mask so that subsequent allow access
 148            control entries do not turn on the bits we are denying */
 149         if (type == ACCESS_DENIED) {
 150                 if (flags & GENERIC_ALL) {
 151                         *pbits_to_set &= ~S_IRWXUGO;
 152                 }
 153                 if ((flags & GENERIC_WRITE) ||
 154                         ((flags & FILE_WRITE_RIGHTS) == FILE_WRITE_RIGHTS))
 155                         *pbits_to_set &= ~S_IWUGO;
 156                 if ((flags & GENERIC_READ) ||
 157                         ((flags & FILE_READ_RIGHTS) == FILE_READ_RIGHTS))
 158                         *pbits_to_set &= ~S_IRUGO;
 159                 if ((flags & GENERIC_EXECUTE) ||
 160                         ((flags & FILE_EXEC_RIGHTS) == FILE_EXEC_RIGHTS))
 161                         *pbits_to_set &= ~S_IXUGO;
 162                 return;
 163         } else if (type != ACCESS_ALLOWED) {
 164                 cERROR(1, ("unknown access control type %d", type));
 165                 return;
 166         }
 167         /* else ACCESS_ALLOWED type */
 168
 169         if (flags & GENERIC_ALL) {
 170                 *pmode |= (S_IRWXUGO & (*pbits_to_set));
 171 #ifdef CONFIG_CIFS_DEBUG2
 172                 cFYI(1, ("all perms"));
 173 #endif
 174                 return;
 175         }
 176         if ((flags & GENERIC_WRITE) ||
 177                         ((flags & FILE_WRITE_RIGHTS) == FILE_WRITE_RIGHTS))
 178                 *pmode |= (S_IWUGO & (*pbits_to_set));
 179         if ((flags & GENERIC_READ) ||
 180                         ((flags & FILE_READ_RIGHTS) == FILE_READ_RIGHTS))
 181                 *pmode |= (S_IRUGO & (*pbits_to_set));
 182         if ((flags & GENERIC_EXECUTE) ||
 183                         ((flags & FILE_EXEC_RIGHTS) == FILE_EXEC_RIGHTS))
 184                 *pmode |= (S_IXUGO & (*pbits_to_set));
 185
 186 #ifdef CONFIG_CIFS_DEBUG2
 187         cFYI(1, ("access flags 0x%x mode now 0x%x", flags, *pmode));
 188 #endif
 189         return;
 190 }
 191
 192 /*
 193    Generate access flags to reflect permissions mode is the existing mode.
 194    This function is called for every ACE in the DACL whose SID matches
 195    with either owner or group or everyone.
 196 */
 197
 198 static void mode_to_access_flags(umode_t mode, umode_t bits_to_use,
 199                                 __u32 *pace_flags)
 200 {
 201         /* reset access mask */
 202         *pace_flags = 0x0;
 203
 204         /* bits to use are either S_IRWXU or S_IRWXG or S_IRWXO */
 205         mode &= bits_to_use;
 206
 207         /* check for R/W/X UGO since we do not know whose flags
 208            is this but we have cleared all the bits sans RWX for
 209            either user or group or other as per bits_to_use */
 210         if (mode & S_IRUGO)
 211                 *pace_flags |= SET_FILE_READ_RIGHTS;
 212         if (mode & S_IWUGO)
 213                 *pace_flags |= SET_FILE_WRITE_RIGHTS;
 214         if (mode & S_IXUGO)
 215                 *pace_flags |= SET_FILE_EXEC_RIGHTS;
 216
 217 #ifdef CONFIG_CIFS_DEBUG2
 218         cFYI(1, ("mode: 0x%x, access flags now 0x%x", mode, *pace_flags));
 219 #endif
 220         return;
 221 }
 222
 223
 224 #ifdef CONFIG_CIFS_DEBUG2
 225 static void dump_ace(struct cifs_ace *pace, char *end_of_acl)
 226 {
 227         int num_subauth;
 228
 229         /* validate that we do not go past end of acl */
 230
 231         if (le16_to_cpu(pace->size) < 16) {
 232                 cERROR(1, ("ACE too small, %d", le16_to_cpu(pace->size)));
 233                 return;
 234         }
 235
 236         if (end_of_acl < (char *)pace + le16_to_cpu(pace->size)) {
 237                 cERROR(1, ("ACL too small to parse ACE"));
 238                 return;
 239         }
 240
 241         num_subauth = pace->sid.num_subauth;
 242         if (num_subauth) {
 243                 int i;
 244                 cFYI(1, ("ACE revision %d num_auth %d type %d flags %d size %d",
 245                         pace->sid.revision, pace->sid.num_subauth, pace->type,
 246                         pace->flags, pace->size));
 247                 for (i = 0; i < num_subauth; ++i) {
 248                         cFYI(1, ("ACE sub_auth[%d]: 0x%x", i,
 249                                 le32_to_cpu(pace->sid.sub_auth[i])));
 250                 }
 251
 252                 /* BB add length check to make sure that we do not have huge
 253                         num auths and therefore go off the end */
 254         }
 255
 256         return;
 257 }
 258 #endif
 259
 260
 261 static void parse_dacl(struct cifs_acl *pdacl, char *end_of_acl,
 262                        struct cifs_sid *pownersid, struct cifs_sid *pgrpsid,
 263                        struct inode *inode)
 264 {
 265         int i;
 266         int num_aces = 0;
 267         int acl_size;
 268         char *acl_base;
 269         struct cifs_ace **ppace;
 270
 271         /* BB need to add parm so we can store the SID BB */
 272
 273         if (!pdacl) {
 274                 /* no DACL in the security descriptor, set
 275                    all the permissions for user/group/other */
 276                 inode->i_mode |= S_IRWXUGO;
 277                 return;
 278         }
 279
 280         /* validate that we do not go past end of acl */
 281         if (end_of_acl < (char *)pdacl + le16_to_cpu(pdacl->size)) {
 282                 cERROR(1, ("ACL too small to parse DACL"));
 283                 return;
 284         }
 285
 286 #ifdef CONFIG_CIFS_DEBUG2
 287         cFYI(1, ("DACL revision %d size %d num aces %d",
 288                 le16_to_cpu(pdacl->revision), le16_to_cpu(pdacl->size),
 289                 le32_to_cpu(pdacl->num_aces)));
 290 #endif
 291
 292         /* reset rwx permissions for user/group/other.
 293            Also, if num_aces is 0 i.e. DACL has no ACEs,
 294            user/group/other have no permissions */
 295         inode->i_mode &= ~(S_IRWXUGO);
 296
 297         acl_base = (char *)pdacl;
 298         acl_size = sizeof(struct cifs_acl);
 299
 300         num_aces = le32_to_cpu(pdacl->num_aces);
 301         if (num_aces  > 0) {
 302                 umode_t user_mask = S_IRWXU;
 303                 umode_t group_mask = S_IRWXG;
 304                 umode_t other_mask = S_IRWXO;
 305
 306                 ppace = kmalloc(num_aces * sizeof(struct cifs_ace *),
 307                                 GFP_KERNEL);
 308
 309 /*              cifscred->cecount = pdacl->num_aces;
 310                 cifscred->aces = kmalloc(num_aces *
 311                         sizeof(struct cifs_ace *), GFP_KERNEL);*/
 312
 313                 for (i = 0; i < num_aces; ++i) {
 314                         ppace[i] = (struct cifs_ace *) (acl_base + acl_size);
 315 #ifdef CONFIG_CIFS_DEBUG2
 316                         dump_ace(ppace[i], end_of_acl);
 317 #endif
 318                         if (compare_sids(&(ppace[i]->sid), pownersid))
 319                                 access_flags_to_mode(ppace[i]->access_req,
 320                                                      ppace[i]->type,
 321                                                      &(inode->i_mode),
 322                                                      &user_mask);
 323                         if (compare_sids(&(ppace[i]->sid), pgrpsid))
 324                                 access_flags_to_mode(ppace[i]->access_req,
 325                                                      ppace[i]->type,
 326                                                      &(inode->i_mode),
 327                                                      &group_mask);
 328                         if (compare_sids(&(ppace[i]->sid), &sid_everyone))
 329                                 access_flags_to_mode(ppace[i]->access_req,
 330                                                      ppace[i]->type,
 331                                                      &(inode->i_mode),
 332                                                      &other_mask);
 333
 334 /*                      memcpy((void *)(&(cifscred->aces[i])),
 335                                 (void *)ppace[i],
 336                                 sizeof(struct cifs_ace)); */
 337
 338                         acl_base = (char *)ppace[i];
 339                         acl_size = le16_to_cpu(ppace[i]->size);
 340                 }
 341
 342                 kfree(ppace);
 343         }
 344
 345         return;
 346 }
 347
 348
 349 static int parse_sid(struct cifs_sid *psid, char *end_of_acl)
 350 {
 351         /* BB need to add parm so we can store the SID BB */
 352
 353         /* validate that we do not go past end of ACL - sid must be at least 8
 354            bytes long (assuming no sub-auths - e.g. the null SID */
 355         if (end_of_acl < (char *)psid + 8) {
 356                 cERROR(1, ("ACL too small to parse SID %p", psid));
 357                 return -EINVAL;
 358         }
 359
 360         if (psid->num_subauth) {
 361 #ifdef CONFIG_CIFS_DEBUG2
 362                 int i;
 363                 cFYI(1, ("SID revision %d num_auth %d",
 364                         psid->revision, psid->num_subauth));
 365
 366                 for (i = 0; i < psid->num_subauth; i++) {
 367                         cFYI(1, ("SID sub_auth[%d]: 0x%x ", i,
 368                                 le32_to_cpu(psid->sub_auth[i])));
 369                 }
 370
 371                 /* BB add length check to make sure that we do not have huge
 372                         num auths and therefore go off the end */
 373                 cFYI(1, ("RID 0x%x",
 374                         le32_to_cpu(psid->sub_auth[psid->num_subauth-1])));
 375 #endif
 376         }
 377
 378         return 0;
 379 }
 380
 381
 382 /* Convert CIFS ACL to POSIX form */
 383 static int parse_sec_desc(struct cifs_ntsd *pntsd, int acl_len,
 384                           struct inode *inode)
 385 {
 386         int rc;
 387         struct cifs_sid *owner_sid_ptr, *group_sid_ptr;
 388         struct cifs_acl *dacl_ptr; /* no need for SACL ptr */
 389         char *end_of_acl = ((char *)pntsd) + acl_len;
 390         __u32 dacloffset;
 391
 392         if ((inode == NULL) || (pntsd == NULL))
 393                 return -EIO;
 394
 395         owner_sid_ptr = (struct cifs_sid *)((char *)pntsd +
 396                                 le32_to_cpu(pntsd->osidoffset));
 397         group_sid_ptr = (struct cifs_sid *)((char *)pntsd +
 398                                 le32_to_cpu(pntsd->gsidoffset));
 399         dacloffset = le32_to_cpu(pntsd->dacloffset);
 400         dacl_ptr = (struct cifs_acl *)((char *)pntsd + dacloffset);
 401 #ifdef CONFIG_CIFS_DEBUG2
 402         cFYI(1, ("revision %d type 0x%x ooffset 0x%x goffset 0x%x "
 403                  "sacloffset 0x%x dacloffset 0x%x",
 404                  pntsd->revision, pntsd->type, le32_to_cpu(pntsd->osidoffset),
 405                  le32_to_cpu(pntsd->gsidoffset),
 406                  le32_to_cpu(pntsd->sacloffset), dacloffset));
 407 #endif
 408 /*      cifs_dump_mem("owner_sid: ", owner_sid_ptr, 64); */
 409         rc = parse_sid(owner_sid_ptr, end_of_acl);
 410         if (rc)
 411                 return rc;
 412
 413         rc = parse_sid(group_sid_ptr, end_of_acl);
 414         if (rc)
 415                 return rc;
 416
 417         if (dacloffset)
 418                 parse_dacl(dacl_ptr, end_of_acl, owner_sid_ptr,
 419                            group_sid_ptr, inode);
 420         else
 421                 cFYI(1, ("no ACL")); /* BB grant all or default perms? */
 422
 423 /*      cifscred->uid = owner_sid_ptr->rid;
 424         cifscred->gid = group_sid_ptr->rid;
 425         memcpy((void *)(&(cifscred->osid)), (void *)owner_sid_ptr,
 426                         sizeof(struct cifs_sid));
 427         memcpy((void *)(&(cifscred->gsid)), (void *)group_sid_ptr,
 428                         sizeof(struct cifs_sid)); */
 429
 430
 431         return (0);
 432 }
 433
 434
 435 /* Retrieve an ACL from the server */
 436 static struct cifs_ntsd *get_cifs_acl(u32 *pacllen, struct inode *inode,
 437                                        const char *path)
 438 {
 439         struct cifsFileInfo *open_file;
 440         int unlock_file = FALSE;
 441         int xid;
 442         int rc = -EIO;
 443         __u16 fid;
 444         struct super_block *sb;
 445         struct cifs_sb_info *cifs_sb;
 446         struct cifs_ntsd *pntsd = NULL;
 447
 448         cFYI(1, ("get mode from ACL for %s", path));
 449
 450         if (inode == NULL)
 451                 return NULL;
 452
 453         xid = GetXid();
 454         open_file = find_readable_file(CIFS_I(inode));
 455         sb = inode->i_sb;
 456         if (sb == NULL) {
 457                 FreeXid(xid);
 458                 return NULL;
 459         }
 460         cifs_sb = CIFS_SB(sb);
 461
 462         if (open_file) {
 463                 unlock_file = TRUE;
 464                 fid = open_file->netfid;
 465         } else {
 466                 int oplock = FALSE;
 467                 /* open file */
 468                 rc = CIFSSMBOpen(xid, cifs_sb->tcon, path, FILE_OPEN,
 469                                 READ_CONTROL, 0, &fid, &oplock, NULL,
 470                                 cifs_sb->local_nls, cifs_sb->mnt_cifs_flags &
 471                                         CIFS_MOUNT_MAP_SPECIAL_CHR);
 472                 if (rc != 0) {
 473                         cERROR(1, ("Unable to open file to get ACL"));
 474                         FreeXid(xid);
 475                         return NULL;
 476                 }
 477         }
 478
 479         rc = CIFSSMBGetCIFSACL(xid, cifs_sb->tcon, fid, &pntsd, pacllen);
 480         cFYI(1, ("GetCIFSACL rc = %d ACL len %d", rc, *pacllen));
 481         if (unlock_file == TRUE)
 482                 atomic_dec(&open_file->wrtPending);
 483         else
 484                 CIFSSMBClose(xid, cifs_sb->tcon, fid);
 485
 486         FreeXid(xid);
 487         return pntsd;
 488 }
 489
 490 /* Translate the CIFS ACL (simlar to NTFS ACL) for a file into mode bits */
 491 void acl_to_uid_mode(struct inode *inode, const char *path)
 492 {
 493         struct cifs_ntsd *pntsd = NULL;
 494         u32 acllen = 0;
 495         int rc = 0;
 496
 497 #ifdef CONFIG_CIFS_DEBUG2
 498         cFYI(1, ("converting ACL to mode for %s", path));
 499 #endif
 500         pntsd = get_cifs_acl(&acllen, inode, path);
 501
 502         /* if we can retrieve the ACL, now parse Access Control Entries, ACEs */
 503         if (pntsd)
 504                 rc = parse_sec_desc(pntsd, acllen, inode);
 505         if (rc)
 506                 cFYI(1, ("parse sec desc failed rc = %d", rc));
 507
 508         kfree(pntsd);
 509         return;
 510 }
 511
 512 /* Convert mode bits to an ACL so we can update the ACL on the server */
 513 int mode_to_acl(struct inode *inode, const char *path)
 514 {
 515         int rc = 0;
 516         __u32 acllen = 0;
 517         struct cifs_ntsd *pntsd = NULL;
 518
 519         cFYI(1, ("set ACL from mode for %s", path));
 520
 521         /* Get the security descriptor */
 522         pntsd = get_cifs_acl(&acllen, inode, path);
 523
 524         /* Add/Modify the three ACEs for owner, group, everyone
 525            while retaining the other ACEs */
 526
 527         /* Set the security descriptor */
 528
 529
 530         kfree(pntsd);
 531         return rc;
 532 }
 533 #endif /* CONFIG_CIFS_EXPERIMENTAL */