security/commoncap.c

   1 /* Common capabilities, needed by capability.o and root_plug.o
   2  *
   3  *      This program is free software; you can redistribute it and/or modify
   4  *      it under the terms of the GNU General Public License as published by
   5  *      the Free Software Foundation; either version 2 of the License, or
   6  *      (at your option) any later version.
   7  *
   8  */
   9
  10 #include <linux/capability.h>
  11 #include <linux/audit.h>
  12 #include <linux/module.h>
  13 #include <linux/init.h>
  14 #include <linux/kernel.h>
  15 #include <linux/security.h>
  16 #include <linux/file.h>
  17 #include <linux/mm.h>
  18 #include <linux/mman.h>
  19 #include <linux/pagemap.h>
  20 #include <linux/swap.h>
  21 #include <linux/skbuff.h>
  22 #include <linux/netlink.h>
  23 #include <linux/ptrace.h>
  24 #include <linux/xattr.h>
  25 #include <linux/hugetlb.h>
  26 #include <linux/mount.h>
  27 #include <linux/sched.h>
  28 #include <linux/prctl.h>
  29 #include <linux/securebits.h>
  30
  31 int cap_netlink_send(struct sock *sk, struct sk_buff *skb)
  32 {
  33         NETLINK_CB(skb).eff_cap = current_cap();
  34         return 0;
  35 }
  36
  37 int cap_netlink_recv(struct sk_buff *skb, int cap)
  38 {
  39         if (!cap_raised(NETLINK_CB(skb).eff_cap, cap))
  40                 return -EPERM;
  41         return 0;
  42 }
  43
  44 EXPORT_SYMBOL(cap_netlink_recv);
  45
  46 /*
  47  * NOTE WELL: cap_capable() cannot be used like the kernel's capable()
  48  * function.  That is, it has the reverse semantics: cap_capable()
  49  * returns 0 when a task has a capability, but the kernel's capable()
  50  * returns 1 for this case.
  51  */
  52 int cap_capable(struct task_struct *tsk, int cap, int audit)
  53 {
  54         /* Derived from include/linux/sched.h:capable. */
  55         if (cap_raised(tsk->cred->cap_effective, cap))
  56                 return 0;
  57         return -EPERM;
  58 }
  59
  60 int cap_settime(struct timespec *ts, struct timezone *tz)
  61 {
  62         if (!capable(CAP_SYS_TIME))
  63                 return -EPERM;
  64         return 0;
  65 }
  66
  67 int cap_ptrace_may_access(struct task_struct *child, unsigned int mode)
  68 {
  69         /* Derived from arch/i386/kernel/ptrace.c:sys_ptrace. */
  70         if (cap_issubset(child->cred->cap_permitted,
  71                          current->cred->cap_permitted))
  72                 return 0;
  73         if (capable(CAP_SYS_PTRACE))
  74                 return 0;
  75         return -EPERM;
  76 }
  77
  78 int cap_ptrace_traceme(struct task_struct *parent)
  79 {
  80         if (cap_issubset(current->cred->cap_permitted,
  81                          parent->cred->cap_permitted))
  82                 return 0;
  83         if (has_capability(parent, CAP_SYS_PTRACE))
  84                 return 0;
  85         return -EPERM;
  86 }
  87
  88 int cap_capget (struct task_struct *target, kernel_cap_t *effective,
  89                 kernel_cap_t *inheritable, kernel_cap_t *permitted)
  90 {
  91         struct cred *cred = target->cred;
  92
  93         /* Derived from kernel/capability.c:sys_capget. */
  94         *effective   = cred->cap_effective;
  95         *inheritable = cred->cap_inheritable;
  96         *permitted   = cred->cap_permitted;
  97         return 0;
  98 }
  99
 100 #ifdef CONFIG_SECURITY_FILE_CAPABILITIES
 101
 102 static inline int cap_inh_is_capped(void)
 103 {
 104         /*
 105          * Return 1 if changes to the inheritable set are limited
 106          * to the old permitted set. That is, if the current task
 107          * does *not* possess the CAP_SETPCAP capability.
 108          */
 109         return (cap_capable(current, CAP_SETPCAP, SECURITY_CAP_AUDIT) != 0);
 110 }
 111
 112 static inline int cap_limit_ptraced_target(void) { return 1; }
 113
 114 #else /* ie., ndef CONFIG_SECURITY_FILE_CAPABILITIES */
 115
 116 static inline int cap_inh_is_capped(void) { return 1; }
 117 static inline int cap_limit_ptraced_target(void)
 118 {
 119         return !capable(CAP_SETPCAP);
 120 }
 121
 122 #endif /* def CONFIG_SECURITY_FILE_CAPABILITIES */
 123
 124 int cap_capset_check(const kernel_cap_t *effective,
 125                      const kernel_cap_t *inheritable,
 126                      const kernel_cap_t *permitted)
 127 {
 128         const struct cred *cred = current->cred;
 129
 130         if (cap_inh_is_capped()
 131             && !cap_issubset(*inheritable,
 132                              cap_combine(cred->cap_inheritable,
 133                                          cred->cap_permitted))) {
 134                 /* incapable of using this inheritable set */
 135                 return -EPERM;
 136         }
 137         if (!cap_issubset(*inheritable,
 138                            cap_combine(cred->cap_inheritable,
 139                                        cred->cap_bset))) {
 140                 /* no new pI capabilities outside bounding set */
 141                 return -EPERM;
 142         }
 143
 144         /* verify restrictions on target's new Permitted set */
 145         if (!cap_issubset (*permitted,
 146                            cap_combine (cred->cap_permitted,
 147                                         cred->cap_permitted))) {
 148                 return -EPERM;
 149         }
 150
 151         /* verify the _new_Effective_ is a subset of the _new_Permitted_ */
 152         if (!cap_issubset (*effective, *permitted)) {
 153                 return -EPERM;
 154         }
 155
 156         return 0;
 157 }
 158
 159 void cap_capset_set(const kernel_cap_t *effective,
 160                     const kernel_cap_t *inheritable,
 161                     const kernel_cap_t *permitted)
 162 {
 163         struct cred *cred = current->cred;
 164
 165         cred->cap_effective   = *effective;
 166         cred->cap_inheritable = *inheritable;
 167         cred->cap_permitted   = *permitted;
 168 }
 169
 170 static inline void bprm_clear_caps(struct linux_binprm *bprm)
 171 {
 172         cap_clear(bprm->cap_post_exec_permitted);
 173         bprm->cap_effective = false;
 174 }
 175
 176 #ifdef CONFIG_SECURITY_FILE_CAPABILITIES
 177
 178 int cap_inode_need_killpriv(struct dentry *dentry)
 179 {
 180         struct inode *inode = dentry->d_inode;
 181         int error;
 182
 183         if (!inode->i_op || !inode->i_op->getxattr)
 184                return 0;
 185
 186         error = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS, NULL, 0);
 187         if (error <= 0)
 188                 return 0;
 189         return 1;
 190 }
 191
 192 int cap_inode_killpriv(struct dentry *dentry)
 193 {
 194         struct inode *inode = dentry->d_inode;
 195
 196         if (!inode->i_op || !inode->i_op->removexattr)
 197                return 0;
 198
 199         return inode->i_op->removexattr(dentry, XATTR_NAME_CAPS);
 200 }
 201
 202 static inline int bprm_caps_from_vfs_caps(struct cpu_vfs_cap_data *caps,
 203                                           struct linux_binprm *bprm)
 204 {
 205         unsigned i;
 206         int ret = 0;
 207
 208         if (caps->magic_etc & VFS_CAP_FLAGS_EFFECTIVE)
 209                 bprm->cap_effective = true;
 210         else
 211                 bprm->cap_effective = false;
 212
 213         CAP_FOR_EACH_U32(i) {
 214                 __u32 permitted = caps->permitted.cap[i];
 215                 __u32 inheritable = caps->inheritable.cap[i];
 216
 217                 /*
 218                  * pP' = (X & fP) | (pI & fI)
 219                  */
 220                 bprm->cap_post_exec_permitted.cap[i] =
 221                         (current->cred->cap_bset.cap[i] & permitted) |
 222                         (current->cred->cap_inheritable.cap[i] & inheritable);
 223
 224                 if (permitted & ~bprm->cap_post_exec_permitted.cap[i]) {
 225                         /*
 226                          * insufficient to execute correctly
 227                          */
 228                         ret = -EPERM;
 229                 }
 230         }
 231
 232         /*
 233          * For legacy apps, with no internal support for recognizing they
 234          * do not have enough capabilities, we return an error if they are
 235          * missing some "forced" (aka file-permitted) capabilities.
 236          */
 237         return bprm->cap_effective ? ret : 0;
 238 }
 239
 240 int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data *cpu_caps)
 241 {
 242         struct inode *inode = dentry->d_inode;
 243         __u32 magic_etc;
 244         unsigned tocopy, i;
 245         int size;
 246         struct vfs_cap_data caps;
 247
 248         memset(cpu_caps, 0, sizeof(struct cpu_vfs_cap_data));
 249
 250         if (!inode || !inode->i_op || !inode->i_op->getxattr)
 251                 return -ENODATA;
 252
 253         size = inode->i_op->getxattr((struct dentry *)dentry, XATTR_NAME_CAPS, &caps,
 254                                    XATTR_CAPS_SZ);
 255         if (size == -ENODATA || size == -EOPNOTSUPP) {
 256                 /* no data, that's ok */
 257                 return -ENODATA;
 258         }
 259         if (size < 0)
 260                 return size;
 261
 262         if (size < sizeof(magic_etc))
 263                 return -EINVAL;
 264
 265         cpu_caps->magic_etc = magic_etc = le32_to_cpu(caps.magic_etc);
 266
 267         switch ((magic_etc & VFS_CAP_REVISION_MASK)) {
 268         case VFS_CAP_REVISION_1:
 269                 if (size != XATTR_CAPS_SZ_1)
 270                         return -EINVAL;
 271                 tocopy = VFS_CAP_U32_1;
 272                 break;
 273         case VFS_CAP_REVISION_2:
 274                 if (size != XATTR_CAPS_SZ_2)
 275                         return -EINVAL;
 276                 tocopy = VFS_CAP_U32_2;
 277                 break;
 278         default:
 279                 return -EINVAL;
 280         }
 281
 282         CAP_FOR_EACH_U32(i) {
 283                 if (i >= tocopy)
 284                         break;
 285                 cpu_caps->permitted.cap[i] = le32_to_cpu(caps.data[i].permitted);
 286                 cpu_caps->inheritable.cap[i] = le32_to_cpu(caps.data[i].inheritable);
 287         }
 288         return 0;
 289 }
 290
 291 /* Locate any VFS capabilities: */
 292 static int get_file_caps(struct linux_binprm *bprm)
 293 {
 294         struct dentry *dentry;
 295         int rc = 0;
 296         struct cpu_vfs_cap_data vcaps;
 297
 298         bprm_clear_caps(bprm);
 299
 300         if (!file_caps_enabled)
 301                 return 0;
 302
 303         if (bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID)
 304                 return 0;
 305
 306         dentry = dget(bprm->file->f_dentry);
 307
 308         rc = get_vfs_caps_from_disk(dentry, &vcaps);
 309         if (rc < 0) {
 310                 if (rc == -EINVAL)
 311                         printk(KERN_NOTICE "%s: get_vfs_caps_from_disk returned %d for %s\n",
 312                                 __func__, rc, bprm->filename);
 313                 else if (rc == -ENODATA)
 314                         rc = 0;
 315                 goto out;
 316         }
 317
 318         rc = bprm_caps_from_vfs_caps(&vcaps, bprm);
 319
 320 out:
 321         dput(dentry);
 322         if (rc)
 323                 bprm_clear_caps(bprm);
 324
 325         return rc;
 326 }
 327
 328 #else
 329 int cap_inode_need_killpriv(struct dentry *dentry)
 330 {
 331         return 0;
 332 }
 333
 334 int cap_inode_killpriv(struct dentry *dentry)
 335 {
 336         return 0;
 337 }
 338
 339 static inline int get_file_caps(struct linux_binprm *bprm)
 340 {
 341         bprm_clear_caps(bprm);
 342         return 0;
 343 }
 344 #endif
 345
 346 int cap_bprm_set_security (struct linux_binprm *bprm)
 347 {
 348         int ret;
 349
 350         ret = get_file_caps(bprm);
 351
 352         if (!issecure(SECURE_NOROOT)) {
 353                 /*
 354                  * To support inheritance of root-permissions and suid-root
 355                  * executables under compatibility mode, we override the
 356                  * capability sets for the file.
 357                  *
 358                  * If only the real uid is 0, we do not set the effective
 359                  * bit.
 360                  */
 361                 if (bprm->e_uid == 0 || current_uid() == 0) {
 362                         /* pP' = (cap_bset & ~0) | (pI & ~0) */
 363                         bprm->cap_post_exec_permitted = cap_combine(
 364                                 current->cred->cap_bset,
 365                                 current->cred->cap_inheritable);
 366                         bprm->cap_effective = (bprm->e_uid == 0);
 367                         ret = 0;
 368                 }
 369         }
 370
 371         return ret;
 372 }
 373
 374 void cap_bprm_apply_creds (struct linux_binprm *bprm, int unsafe)
 375 {
 376         struct cred *cred = current->cred;
 377
 378         if (bprm->e_uid != cred->uid || bprm->e_gid != cred->gid ||
 379             !cap_issubset(bprm->cap_post_exec_permitted,
 380                           cred->cap_permitted)) {
 381                 set_dumpable(current->mm, suid_dumpable);
 382                 current->pdeath_signal = 0;
 383
 384                 if (unsafe & ~LSM_UNSAFE_PTRACE_CAP) {
 385                         if (!capable(CAP_SETUID)) {
 386                                 bprm->e_uid = cred->uid;
 387                                 bprm->e_gid = cred->gid;
 388                         }
 389                         if (cap_limit_ptraced_target()) {
 390                                 bprm->cap_post_exec_permitted = cap_intersect(
 391                                         bprm->cap_post_exec_permitted,
 392                                         cred->cap_permitted);
 393                         }
 394                 }
 395         }
 396
 397         cred->suid = cred->euid = cred->fsuid = bprm->e_uid;
 398         cred->sgid = cred->egid = cred->fsgid = bprm->e_gid;
 399
 400         /* For init, we want to retain the capabilities set
 401          * in the init_task struct. Thus we skip the usual
 402          * capability rules */
 403         if (!is_global_init(current)) {
 404                 cred->cap_permitted = bprm->cap_post_exec_permitted;
 405                 if (bprm->cap_effective)
 406                         cred->cap_effective = bprm->cap_post_exec_permitted;
 407                 else
 408                         cap_clear(cred->cap_effective);
 409         }
 410
 411         /*
 412          * Audit candidate if current->cap_effective is set
 413          *
 414          * We do not bother to audit if 3 things are true:
 415          *   1) cap_effective has all caps
 416          *   2) we are root
 417          *   3) root is supposed to have all caps (SECURE_NOROOT)
 418          * Since this is just a normal root execing a process.
 419          *
 420          * Number 1 above might fail if you don't have a full bset, but I think
 421          * that is interesting information to audit.
 422          */
 423         if (!cap_isclear(cred->cap_effective)) {
 424                 if (!cap_issubset(CAP_FULL_SET, cred->cap_effective) ||
 425                     (bprm->e_uid != 0) || (cred->uid != 0) ||
 426                     issecure(SECURE_NOROOT))
 427                         audit_log_bprm_fcaps(bprm, &cred->cap_permitted,
 428                                              &cred->cap_effective);
 429         }
 430
 431         cred->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);
 432 }
 433
 434 int cap_bprm_secureexec (struct linux_binprm *bprm)
 435 {
 436         const struct cred *cred = current->cred;
 437
 438         if (cred->uid != 0) {
 439                 if (bprm->cap_effective)
 440                         return 1;
 441                 if (!cap_isclear(bprm->cap_post_exec_permitted))
 442                         return 1;
 443         }
 444
 445         return (cred->euid != cred->uid ||
 446                 cred->egid != cred->gid);
 447 }
 448
 449 int cap_inode_setxattr(struct dentry *dentry, const char *name,
 450                        const void *value, size_t size, int flags)
 451 {
 452         if (!strcmp(name, XATTR_NAME_CAPS)) {
 453                 if (!capable(CAP_SETFCAP))
 454                         return -EPERM;
 455                 return 0;
 456         } else if (!strncmp(name, XATTR_SECURITY_PREFIX,
 457                      sizeof(XATTR_SECURITY_PREFIX) - 1)  &&
 458             !capable(CAP_SYS_ADMIN))
 459                 return -EPERM;
 460         return 0;
 461 }
 462
 463 int cap_inode_removexattr(struct dentry *dentry, const char *name)
 464 {
 465         if (!strcmp(name, XATTR_NAME_CAPS)) {
 466                 if (!capable(CAP_SETFCAP))
 467                         return -EPERM;
 468                 return 0;
 469         } else if (!strncmp(name, XATTR_SECURITY_PREFIX,
 470                      sizeof(XATTR_SECURITY_PREFIX) - 1)  &&
 471             !capable(CAP_SYS_ADMIN))
 472                 return -EPERM;
 473         return 0;
 474 }
 475
 476 /* moved from kernel/sys.c. */
 477 /*
 478  * cap_emulate_setxuid() fixes the effective / permitted capabilities of
 479  * a process after a call to setuid, setreuid, or setresuid.
 480  *
 481  *  1) When set*uiding _from_ one of {r,e,s}uid == 0 _to_ all of
 482  *  {r,e,s}uid != 0, the permitted and effective capabilities are
 483  *  cleared.
 484  *
 485  *  2) When set*uiding _from_ euid == 0 _to_ euid != 0, the effective
 486  *  capabilities of the process are cleared.
 487  *
 488  *  3) When set*uiding _from_ euid != 0 _to_ euid == 0, the effective
 489  *  capabilities are set to the permitted capabilities.
 490  *
 491  *  fsuid is handled elsewhere. fsuid == 0 and {r,e,s}uid!= 0 should
 492  *  never happen.
 493  *
 494  *  -astor
 495  *
 496  * cevans - New behaviour, Oct '99
 497  * A process may, via prctl(), elect to keep its capabilities when it
 498  * calls setuid() and switches away from uid==0. Both permitted and
 499  * effective sets will be retained.
 500  * Without this change, it was impossible for a daemon to drop only some
 501  * of its privilege. The call to setuid(!=0) would drop all privileges!
 502  * Keeping uid 0 is not an option because uid 0 owns too many vital
 503  * files..
 504  * Thanks to Olaf Kirch and Peter Benie for spotting this.
 505  */
 506 static inline void cap_emulate_setxuid (int old_ruid, int old_euid,
 507                                         int old_suid)
 508 {
 509         struct cred *cred = current->cred;
 510
 511         if ((old_ruid == 0 || old_euid == 0 || old_suid == 0) &&
 512             (cred->uid != 0 && cred->euid != 0 && cred->suid != 0) &&
 513             !issecure(SECURE_KEEP_CAPS)) {
 514                 cap_clear (cred->cap_permitted);
 515                 cap_clear (cred->cap_effective);
 516         }
 517         if (old_euid == 0 && cred->euid != 0) {
 518                 cap_clear (cred->cap_effective);
 519         }
 520         if (old_euid != 0 && cred->euid == 0) {
 521                 cred->cap_effective = cred->cap_permitted;
 522         }
 523 }
 524
 525 int cap_task_post_setuid (uid_t old_ruid, uid_t old_euid, uid_t old_suid,
 526                           int flags)
 527 {
 528         struct cred *cred = current->cred;
 529
 530         switch (flags) {
 531         case LSM_SETID_RE:
 532         case LSM_SETID_ID:
 533         case LSM_SETID_RES:
 534                 /* Copied from kernel/sys.c:setreuid/setuid/setresuid. */
 535                 if (!issecure (SECURE_NO_SETUID_FIXUP)) {
 536                         cap_emulate_setxuid (old_ruid, old_euid, old_suid);
 537                 }
 538                 break;
 539         case LSM_SETID_FS:
 540                 {
 541                         uid_t old_fsuid = old_ruid;
 542
 543                         /* Copied from kernel/sys.c:setfsuid. */
 544
 545                         /*
 546                          * FIXME - is fsuser used for all CAP_FS_MASK capabilities?
 547                          *          if not, we might be a bit too harsh here.
 548                          */
 549
 550                         if (!issecure (SECURE_NO_SETUID_FIXUP)) {
 551                                 if (old_fsuid == 0 && cred->fsuid != 0) {
 552                                         cred->cap_effective =
 553                                                 cap_drop_fs_set(
 554                                                         cred->cap_effective);
 555                                 }
 556                                 if (old_fsuid != 0 && cred->fsuid == 0) {
 557                                         cred->cap_effective =
 558                                                 cap_raise_fs_set(
 559                                                     cred->cap_effective,
 560                                                     cred->cap_permitted);
 561                                 }
 562                         }
 563                         break;
 564                 }
 565         default:
 566                 return -EINVAL;
 567         }
 568
 569         return 0;
 570 }
 571
 572 #ifdef CONFIG_SECURITY_FILE_CAPABILITIES
 573 /*
 574  * Rationale: code calling task_setscheduler, task_setioprio, and
 575  * task_setnice, assumes that
 576  *   . if capable(cap_sys_nice), then those actions should be allowed
 577  *   . if not capable(cap_sys_nice), but acting on your own processes,
 578  *      then those actions should be allowed
 579  * This is insufficient now since you can call code without suid, but
 580  * yet with increased caps.
 581  * So we check for increased caps on the target process.
 582  */
 583 static int cap_safe_nice(struct task_struct *p)
 584 {
 585         if (!cap_issubset(p->cred->cap_permitted,
 586                           current->cred->cap_permitted) &&
 587             !capable(CAP_SYS_NICE))
 588                 return -EPERM;
 589         return 0;
 590 }
 591
 592 int cap_task_setscheduler (struct task_struct *p, int policy,
 593                            struct sched_param *lp)
 594 {
 595         return cap_safe_nice(p);
 596 }
 597
 598 int cap_task_setioprio (struct task_struct *p, int ioprio)
 599 {
 600         return cap_safe_nice(p);
 601 }
 602
 603 int cap_task_setnice (struct task_struct *p, int nice)
 604 {
 605         return cap_safe_nice(p);
 606 }
 607
 608 /*
 609  * called from kernel/sys.c for prctl(PR_CABSET_DROP)
 610  * done without task_capability_lock() because it introduces
 611  * no new races - i.e. only another task doing capget() on
 612  * this task could get inconsistent info.  There can be no
 613  * racing writer bc a task can only change its own caps.
 614  */
 615 static long cap_prctl_drop(unsigned long cap)
 616 {
 617         if (!capable(CAP_SETPCAP))
 618                 return -EPERM;
 619         if (!cap_valid(cap))
 620                 return -EINVAL;
 621         cap_lower(current->cred->cap_bset, cap);
 622         return 0;
 623 }
 624
 625 #else
 626 int cap_task_setscheduler (struct task_struct *p, int policy,
 627                            struct sched_param *lp)
 628 {
 629         return 0;
 630 }
 631 int cap_task_setioprio (struct task_struct *p, int ioprio)
 632 {
 633         return 0;
 634 }
 635 int cap_task_setnice (struct task_struct *p, int nice)
 636 {
 637         return 0;
 638 }
 639 #endif
 640
 641 int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3,
 642                    unsigned long arg4, unsigned long arg5, long *rc_p)
 643 {
 644         struct cred *cred = current_cred();
 645         long error = 0;
 646
 647         switch (option) {
 648         case PR_CAPBSET_READ:
 649                 if (!cap_valid(arg2))
 650                         error = -EINVAL;
 651                 else
 652                         error = !!cap_raised(cred->cap_bset, arg2);
 653                 break;
 654 #ifdef CONFIG_SECURITY_FILE_CAPABILITIES
 655         case PR_CAPBSET_DROP:
 656                 error = cap_prctl_drop(arg2);
 657                 break;
 658
 659         /*
 660          * The next four prctl's remain to assist with transitioning a
 661          * system from legacy UID=0 based privilege (when filesystem
 662          * capabilities are not in use) to a system using filesystem
 663          * capabilities only - as the POSIX.1e draft intended.
 664          *
 665          * Note:
 666          *
 667          *  PR_SET_SECUREBITS =
 668          *      issecure_mask(SECURE_KEEP_CAPS_LOCKED)
 669          *    | issecure_mask(SECURE_NOROOT)
 670          *    | issecure_mask(SECURE_NOROOT_LOCKED)
 671          *    | issecure_mask(SECURE_NO_SETUID_FIXUP)
 672          *    | issecure_mask(SECURE_NO_SETUID_FIXUP_LOCKED)
 673          *
 674          * will ensure that the current process and all of its
 675          * children will be locked into a pure
 676          * capability-based-privilege environment.
 677          */
 678         case PR_SET_SECUREBITS:
 679                 if ((((cred->securebits & SECURE_ALL_LOCKS) >> 1)
 680                      & (cred->securebits ^ arg2))                  /*[1]*/
 681                     || ((cred->securebits & SECURE_ALL_LOCKS
 682                          & ~arg2))                                    /*[2]*/
 683                     || (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS)) /*[3]*/
 684                     || (cap_capable(current, CAP_SETPCAP, SECURITY_CAP_AUDIT) != 0)) { /*[4]*/
 685                         /*
 686                          * [1] no changing of bits that are locked
 687                          * [2] no unlocking of locks
 688                          * [3] no setting of unsupported bits
 689                          * [4] doing anything requires privilege (go read about
 690                          *     the "sendmail capabilities bug")
 691                          */
 692                         error = -EPERM;  /* cannot change a locked bit */
 693                 } else {
 694                         cred->securebits = arg2;
 695                 }
 696                 break;
 697         case PR_GET_SECUREBITS:
 698                 error = cred->securebits;
 699                 break;
 700
 701 #endif /* def CONFIG_SECURITY_FILE_CAPABILITIES */
 702
 703         case PR_GET_KEEPCAPS:
 704                 if (issecure(SECURE_KEEP_CAPS))
 705                         error = 1;
 706                 break;
 707         case PR_SET_KEEPCAPS:
 708                 if (arg2 > 1) /* Note, we rely on arg2 being unsigned here */
 709                         error = -EINVAL;
 710                 else if (issecure(SECURE_KEEP_CAPS_LOCKED))
 711                         error = -EPERM;
 712                 else if (arg2)
 713                         cred->securebits |= issecure_mask(SECURE_KEEP_CAPS);
 714                 else
 715                         cred->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);
 716                 break;
 717
 718         default:
 719                 /* No functionality available - continue with default */
 720                 return 0;
 721         }
 722
 723         /* Functionality provided */
 724         *rc_p = error;
 725         return 1;
 726 }
 727
 728 void cap_task_reparent_to_init (struct task_struct *p)
 729 {
 730         struct cred *cred = p->cred;
 731
 732         cap_set_init_eff(cred->cap_effective);
 733         cap_clear(cred->cap_inheritable);
 734         cap_set_full(cred->cap_permitted);
 735         p->cred->securebits = SECUREBITS_DEFAULT;
 736 }
 737
 738 int cap_syslog (int type)
 739 {
 740         if ((type != 3 && type != 10) && !capable(CAP_SYS_ADMIN))
 741                 return -EPERM;
 742         return 0;
 743 }
 744
 745 int cap_vm_enough_memory(struct mm_struct *mm, long pages)
 746 {
 747         int cap_sys_admin = 0;
 748
 749         if (cap_capable(current, CAP_SYS_ADMIN, SECURITY_CAP_NOAUDIT) == 0)
 750                 cap_sys_admin = 1;
 751         return __vm_enough_memory(mm, pages, cap_sys_admin);
 752 }
 753