security/commoncap.c

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This source file includes following definitions.
warn_setuid_and_fcaps_mixed
cap_capable
cap_settime
cap_ptrace_access_check
cap_ptrace_traceme
cap_capget
cap_inh_is_capped
cap_capset
cap_inode_need_killpriv
cap_inode_killpriv
rootid_owns_currentns
sansflags
is_v2header
is_v3header
cap_inode_getsecurity
rootid_from_xattr
validheader
cap_convert_nscap
bprm_caps_from_vfs_caps
get_vfs_caps_from_disk
get_file_caps
root_privileged
__is_real
__is_eff
__is_suid
handle_privileged_root
__is_setuid
__is_setgid
nonroot_raised_pE
cap_bprm_set_creds
cap_inode_setxattr
cap_inode_removexattr
cap_emulate_setxuid
cap_task_fix_setuid
cap_safe_nice
cap_task_setscheduler
cap_task_setioprio
cap_task_setnice
cap_prctl_drop
cap_task_prctl
cap_vm_enough_memory
cap_mmap_addr
cap_mmap_file
capability_init
   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* Common capabilities, needed by capability.o.
   3  */
   4 
   5 #include <linux/capability.h>
   6 #include <linux/audit.h>
   7 #include <linux/init.h>
   8 #include <linux/kernel.h>
   9 #include <linux/lsm_hooks.h>
  10 #include <linux/file.h>
  11 #include <linux/mm.h>
  12 #include <linux/mman.h>
  13 #include <linux/pagemap.h>
  14 #include <linux/swap.h>
  15 #include <linux/skbuff.h>
  16 #include <linux/netlink.h>
  17 #include <linux/ptrace.h>
  18 #include <linux/xattr.h>
  19 #include <linux/hugetlb.h>
  20 #include <linux/mount.h>
  21 #include <linux/sched.h>
  22 #include <linux/prctl.h>
  23 #include <linux/securebits.h>
  24 #include <linux/user_namespace.h>
  25 #include <linux/binfmts.h>
  26 #include <linux/personality.h>
  27 
  28 /*
  29  * If a non-root user executes a setuid-root binary in
  30  * !secure(SECURE_NOROOT) mode, then we raise capabilities.
  31  * However if fE is also set, then the intent is for only
  32  * the file capabilities to be applied, and the setuid-root
  33  * bit is left on either to change the uid (plausible) or
  34  * to get full privilege on a kernel without file capabilities
  35  * support.  So in that case we do not raise capabilities.
  36  *
  37  * Warn if that happens, once per boot.
  38  */
  39 static void warn_setuid_and_fcaps_mixed(const char *fname)
  40 {
  41         static int warned;
  42         if (!warned) {
  43                 printk(KERN_INFO "warning: `%s' has both setuid-root and"
  44                         " effective capabilities. Therefore not raising all"
  45                         " capabilities.\n", fname);
  46                 warned = 1;
  47         }
  48 }
  49 
  50 /**
  51  * cap_capable - Determine whether a task has a particular effective capability
  52  * @cred: The credentials to use
  53  * @ns:  The user namespace in which we need the capability
  54  * @cap: The capability to check for
  55  * @opts: Bitmask of options defined in include/linux/security.h
  56  *
  57  * Determine whether the nominated task has the specified capability amongst
  58  * its effective set, returning 0 if it does, -ve if it does not.
  59  *
  60  * NOTE WELL: cap_has_capability() cannot be used like the kernel's capable()
  61  * and has_capability() functions.  That is, it has the reverse semantics:
  62  * cap_has_capability() returns 0 when a task has a capability, but the
  63  * kernel's capable() and has_capability() returns 1 for this case.
  64  */
  65 int cap_capable(const struct cred *cred, struct user_namespace *targ_ns,
  66                 int cap, unsigned int opts)
  67 {
  68         struct user_namespace *ns = targ_ns;
  69 
  70         /* See if cred has the capability in the target user namespace
  71          * by examining the target user namespace and all of the target
  72          * user namespace's parents.
  73          */
  74         for (;;) {
  75                 /* Do we have the necessary capabilities? */
  76                 if (ns == cred->user_ns)
  77                         return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM;
  78 
  79                 /*
  80                  * If we're already at a lower level than we're looking for,
  81                  * we're done searching.
  82                  */
  83                 if (ns->level <= cred->user_ns->level)
  84                         return -EPERM;
  85 
  86                 /* 
  87                  * The owner of the user namespace in the parent of the
  88                  * user namespace has all caps.
  89                  */
  90                 if ((ns->parent == cred->user_ns) && uid_eq(ns->owner, cred->euid))
  91                         return 0;
  92 
  93                 /*
  94                  * If you have a capability in a parent user ns, then you have
  95                  * it over all children user namespaces as well.
  96                  */
  97                 ns = ns->parent;
  98         }
  99 
 100         /* We never get here */
 101 }
 102 
 103 /**
 104  * cap_settime - Determine whether the current process may set the system clock
 105  * @ts: The time to set
 106  * @tz: The timezone to set
 107  *
 108  * Determine whether the current process may set the system clock and timezone
 109  * information, returning 0 if permission granted, -ve if denied.
 110  */
 111 int cap_settime(const struct timespec64 *ts, const struct timezone *tz)
 112 {
 113         if (!capable(CAP_SYS_TIME))
 114                 return -EPERM;
 115         return 0;
 116 }
 117 
 118 /**
 119  * cap_ptrace_access_check - Determine whether the current process may access
 120  *                         another
 121  * @child: The process to be accessed
 122  * @mode: The mode of attachment.
 123  *
 124  * If we are in the same or an ancestor user_ns and have all the target
 125  * task's capabilities, then ptrace access is allowed.
 126  * If we have the ptrace capability to the target user_ns, then ptrace
 127  * access is allowed.
 128  * Else denied.
 129  *
 130  * Determine whether a process may access another, returning 0 if permission
 131  * granted, -ve if denied.
 132  */
 133 int cap_ptrace_access_check(struct task_struct *child, unsigned int mode)
 134 {
 135         int ret = 0;
 136         const struct cred *cred, *child_cred;
 137         const kernel_cap_t *caller_caps;
 138 
 139         rcu_read_lock();
 140         cred = current_cred();
 141         child_cred = __task_cred(child);
 142         if (mode & PTRACE_MODE_FSCREDS)
 143                 caller_caps = &cred->cap_effective;
 144         else
 145                 caller_caps = &cred->cap_permitted;
 146         if (cred->user_ns == child_cred->user_ns &&
 147             cap_issubset(child_cred->cap_permitted, *caller_caps))
 148                 goto out;
 149         if (ns_capable(child_cred->user_ns, CAP_SYS_PTRACE))
 150                 goto out;
 151         ret = -EPERM;
 152 out:
 153         rcu_read_unlock();
 154         return ret;
 155 }
 156 
 157 /**
 158  * cap_ptrace_traceme - Determine whether another process may trace the current
 159  * @parent: The task proposed to be the tracer
 160  *
 161  * If parent is in the same or an ancestor user_ns and has all current's
 162  * capabilities, then ptrace access is allowed.
 163  * If parent has the ptrace capability to current's user_ns, then ptrace
 164  * access is allowed.
 165  * Else denied.
 166  *
 167  * Determine whether the nominated task is permitted to trace the current
 168  * process, returning 0 if permission is granted, -ve if denied.
 169  */
 170 int cap_ptrace_traceme(struct task_struct *parent)
 171 {
 172         int ret = 0;
 173         const struct cred *cred, *child_cred;
 174 
 175         rcu_read_lock();
 176         cred = __task_cred(parent);
 177         child_cred = current_cred();
 178         if (cred->user_ns == child_cred->user_ns &&
 179             cap_issubset(child_cred->cap_permitted, cred->cap_permitted))
 180                 goto out;
 181         if (has_ns_capability(parent, child_cred->user_ns, CAP_SYS_PTRACE))
 182                 goto out;
 183         ret = -EPERM;
 184 out:
 185         rcu_read_unlock();
 186         return ret;
 187 }
 188 
 189 /**
 190  * cap_capget - Retrieve a task's capability sets
 191  * @target: The task from which to retrieve the capability sets
 192  * @effective: The place to record the effective set
 193  * @inheritable: The place to record the inheritable set
 194  * @permitted: The place to record the permitted set
 195  *
 196  * This function retrieves the capabilities of the nominated task and returns
 197  * them to the caller.
 198  */
 199 int cap_capget(struct task_struct *target, kernel_cap_t *effective,
 200                kernel_cap_t *inheritable, kernel_cap_t *permitted)
 201 {
 202         const struct cred *cred;
 203 
 204         /* Derived from kernel/capability.c:sys_capget. */
 205         rcu_read_lock();
 206         cred = __task_cred(target);
 207         *effective   = cred->cap_effective;
 208         *inheritable = cred->cap_inheritable;
 209         *permitted   = cred->cap_permitted;
 210         rcu_read_unlock();
 211         return 0;
 212 }
 213 
 214 /*
 215  * Determine whether the inheritable capabilities are limited to the old
 216  * permitted set.  Returns 1 if they are limited, 0 if they are not.
 217  */
 218 static inline int cap_inh_is_capped(void)
 219 {
 220         /* they are so limited unless the current task has the CAP_SETPCAP
 221          * capability
 222          */
 223         if (cap_capable(current_cred(), current_cred()->user_ns,
 224                         CAP_SETPCAP, CAP_OPT_NONE) == 0)
 225                 return 0;
 226         return 1;
 227 }
 228 
 229 /**
 230  * cap_capset - Validate and apply proposed changes to current's capabilities
 231  * @new: The proposed new credentials; alterations should be made here
 232  * @old: The current task's current credentials
 233  * @effective: A pointer to the proposed new effective capabilities set
 234  * @inheritable: A pointer to the proposed new inheritable capabilities set
 235  * @permitted: A pointer to the proposed new permitted capabilities set
 236  *
 237  * This function validates and applies a proposed mass change to the current
 238  * process's capability sets.  The changes are made to the proposed new
 239  * credentials, and assuming no error, will be committed by the caller of LSM.
 240  */
 241 int cap_capset(struct cred *new,
 242                const struct cred *old,
 243                const kernel_cap_t *effective,
 244                const kernel_cap_t *inheritable,
 245                const kernel_cap_t *permitted)
 246 {
 247         if (cap_inh_is_capped() &&
 248             !cap_issubset(*inheritable,
 249                           cap_combine(old->cap_inheritable,
 250                                       old->cap_permitted)))
 251                 /* incapable of using this inheritable set */
 252                 return -EPERM;
 253 
 254         if (!cap_issubset(*inheritable,
 255                           cap_combine(old->cap_inheritable,
 256                                       old->cap_bset)))
 257                 /* no new pI capabilities outside bounding set */
 258                 return -EPERM;
 259 
 260         /* verify restrictions on target's new Permitted set */
 261         if (!cap_issubset(*permitted, old->cap_permitted))
 262                 return -EPERM;
 263 
 264         /* verify the _new_Effective_ is a subset of the _new_Permitted_ */
 265         if (!cap_issubset(*effective, *permitted))
 266                 return -EPERM;
 267 
 268         new->cap_effective   = *effective;
 269         new->cap_inheritable = *inheritable;
 270         new->cap_permitted   = *permitted;
 271 
 272         /*
 273          * Mask off ambient bits that are no longer both permitted and
 274          * inheritable.
 275          */
 276         new->cap_ambient = cap_intersect(new->cap_ambient,
 277                                          cap_intersect(*permitted,
 278                                                        *inheritable));
 279         if (WARN_ON(!cap_ambient_invariant_ok(new)))
 280                 return -EINVAL;
 281         return 0;
 282 }
 283 
 284 /**
 285  * cap_inode_need_killpriv - Determine if inode change affects privileges
 286  * @dentry: The inode/dentry in being changed with change marked ATTR_KILL_PRIV
 287  *
 288  * Determine if an inode having a change applied that's marked ATTR_KILL_PRIV
 289  * affects the security markings on that inode, and if it is, should
 290  * inode_killpriv() be invoked or the change rejected.
 291  *
 292  * Returns 1 if security.capability has a value, meaning inode_killpriv()
 293  * is required, 0 otherwise, meaning inode_killpriv() is not required.
 294  */
 295 int cap_inode_need_killpriv(struct dentry *dentry)
 296 {
 297         struct inode *inode = d_backing_inode(dentry);
 298         int error;
 299 
 300         error = __vfs_getxattr(dentry, inode, XATTR_NAME_CAPS, NULL, 0);
 301         return error > 0;
 302 }
 303 
 304 /**
 305  * cap_inode_killpriv - Erase the security markings on an inode
 306  * @dentry: The inode/dentry to alter
 307  *
 308  * Erase the privilege-enhancing security markings on an inode.
 309  *
 310  * Returns 0 if successful, -ve on error.
 311  */
 312 int cap_inode_killpriv(struct dentry *dentry)
 313 {
 314         int error;
 315 
 316         error = __vfs_removexattr(dentry, XATTR_NAME_CAPS);
 317         if (error == -EOPNOTSUPP)
 318                 error = 0;
 319         return error;
 320 }
 321 
 322 static bool rootid_owns_currentns(kuid_t kroot)
 323 {
 324         struct user_namespace *ns;
 325 
 326         if (!uid_valid(kroot))
 327                 return false;
 328 
 329         for (ns = current_user_ns(); ; ns = ns->parent) {
 330                 if (from_kuid(ns, kroot) == 0)
 331                         return true;
 332                 if (ns == &init_user_ns)
 333                         break;
 334         }
 335 
 336         return false;
 337 }
 338 
 339 static __u32 sansflags(__u32 m)
 340 {
 341         return m & ~VFS_CAP_FLAGS_EFFECTIVE;
 342 }
 343 
 344 static bool is_v2header(size_t size, const struct vfs_cap_data *cap)
 345 {
 346         if (size != XATTR_CAPS_SZ_2)
 347                 return false;
 348         return sansflags(le32_to_cpu(cap->magic_etc)) == VFS_CAP_REVISION_2;
 349 }
 350 
 351 static bool is_v3header(size_t size, const struct vfs_cap_data *cap)
 352 {
 353         if (size != XATTR_CAPS_SZ_3)
 354                 return false;
 355         return sansflags(le32_to_cpu(cap->magic_etc)) == VFS_CAP_REVISION_3;
 356 }
 357 
 358 /*
 359  * getsecurity: We are called for security.* before any attempt to read the
 360  * xattr from the inode itself.
 361  *
 362  * This gives us a chance to read the on-disk value and convert it.  If we
 363  * return -EOPNOTSUPP, then vfs_getxattr() will call the i_op handler.
 364  *
 365  * Note we are not called by vfs_getxattr_alloc(), but that is only called
 366  * by the integrity subsystem, which really wants the unconverted values -
 367  * so that's good.
 368  */
 369 int cap_inode_getsecurity(struct inode *inode, const char *name, void **buffer,
 370                           bool alloc)
 371 {
 372         int size, ret;
 373         kuid_t kroot;
 374         uid_t root, mappedroot;
 375         char *tmpbuf = NULL;
 376         struct vfs_cap_data *cap;
 377         struct vfs_ns_cap_data *nscap;
 378         struct dentry *dentry;
 379         struct user_namespace *fs_ns;
 380 
 381         if (strcmp(name, "capability") != 0)
 382                 return -EOPNOTSUPP;
 383 
 384         dentry = d_find_any_alias(inode);
 385         if (!dentry)
 386                 return -EINVAL;
 387 
 388         size = sizeof(struct vfs_ns_cap_data);
 389         ret = (int) vfs_getxattr_alloc(dentry, XATTR_NAME_CAPS,
 390                                  &tmpbuf, size, GFP_NOFS);
 391         dput(dentry);
 392 
 393         if (ret < 0)
 394                 return ret;
 395 
 396         fs_ns = inode->i_sb->s_user_ns;
 397         cap = (struct vfs_cap_data *) tmpbuf;
 398         if (is_v2header((size_t) ret, cap)) {
 399                 /* If this is sizeof(vfs_cap_data) then we're ok with the
 400                  * on-disk value, so return that.  */
 401                 if (alloc)
 402                         *buffer = tmpbuf;
 403                 else
 404                         kfree(tmpbuf);
 405                 return ret;
 406         } else if (!is_v3header((size_t) ret, cap)) {
 407                 kfree(tmpbuf);
 408                 return -EINVAL;
 409         }
 410 
 411         nscap = (struct vfs_ns_cap_data *) tmpbuf;
 412         root = le32_to_cpu(nscap->rootid);
 413         kroot = make_kuid(fs_ns, root);
 414 
 415         /* If the root kuid maps to a valid uid in current ns, then return
 416          * this as a nscap. */
 417         mappedroot = from_kuid(current_user_ns(), kroot);
 418         if (mappedroot != (uid_t)-1 && mappedroot != (uid_t)0) {
 419                 if (alloc) {
 420                         *buffer = tmpbuf;
 421                         nscap->rootid = cpu_to_le32(mappedroot);
 422                 } else
 423                         kfree(tmpbuf);
 424                 return size;
 425         }
 426 
 427         if (!rootid_owns_currentns(kroot)) {
 428                 kfree(tmpbuf);
 429                 return -EOPNOTSUPP;
 430         }
 431 
 432         /* This comes from a parent namespace.  Return as a v2 capability */
 433         size = sizeof(struct vfs_cap_data);
 434         if (alloc) {
 435                 *buffer = kmalloc(size, GFP_ATOMIC);
 436                 if (*buffer) {
 437                         struct vfs_cap_data *cap = *buffer;
 438                         __le32 nsmagic, magic;
 439                         magic = VFS_CAP_REVISION_2;
 440                         nsmagic = le32_to_cpu(nscap->magic_etc);
 441                         if (nsmagic & VFS_CAP_FLAGS_EFFECTIVE)
 442                                 magic |= VFS_CAP_FLAGS_EFFECTIVE;
 443                         memcpy(&cap->data, &nscap->data, sizeof(__le32) * 2 * VFS_CAP_U32);
 444                         cap->magic_etc = cpu_to_le32(magic);
 445                 } else {
 446                         size = -ENOMEM;
 447                 }
 448         }
 449         kfree(tmpbuf);
 450         return size;
 451 }
 452 
 453 static kuid_t rootid_from_xattr(const void *value, size_t size,
 454                                 struct user_namespace *task_ns)
 455 {
 456         const struct vfs_ns_cap_data *nscap = value;
 457         uid_t rootid = 0;
 458 
 459         if (size == XATTR_CAPS_SZ_3)
 460                 rootid = le32_to_cpu(nscap->rootid);
 461 
 462         return make_kuid(task_ns, rootid);
 463 }
 464 
 465 static bool validheader(size_t size, const struct vfs_cap_data *cap)
 466 {
 467         return is_v2header(size, cap) || is_v3header(size, cap);
 468 }
 469 
 470 /*
 471  * User requested a write of security.capability.  If needed, update the
 472  * xattr to change from v2 to v3, or to fixup the v3 rootid.
 473  *
 474  * If all is ok, we return the new size, on error return < 0.
 475  */
 476 int cap_convert_nscap(struct dentry *dentry, void **ivalue, size_t size)
 477 {
 478         struct vfs_ns_cap_data *nscap;
 479         uid_t nsrootid;
 480         const struct vfs_cap_data *cap = *ivalue;
 481         __u32 magic, nsmagic;
 482         struct inode *inode = d_backing_inode(dentry);
 483         struct user_namespace *task_ns = current_user_ns(),
 484                 *fs_ns = inode->i_sb->s_user_ns;
 485         kuid_t rootid;
 486         size_t newsize;
 487 
 488         if (!*ivalue)
 489                 return -EINVAL;
 490         if (!validheader(size, cap))
 491                 return -EINVAL;
 492         if (!capable_wrt_inode_uidgid(inode, CAP_SETFCAP))
 493                 return -EPERM;
 494         if (size == XATTR_CAPS_SZ_2)
 495                 if (ns_capable(inode->i_sb->s_user_ns, CAP_SETFCAP))
 496                         /* user is privileged, just write the v2 */
 497                         return size;
 498 
 499         rootid = rootid_from_xattr(*ivalue, size, task_ns);
 500         if (!uid_valid(rootid))
 501                 return -EINVAL;
 502 
 503         nsrootid = from_kuid(fs_ns, rootid);
 504         if (nsrootid == -1)
 505                 return -EINVAL;
 506 
 507         newsize = sizeof(struct vfs_ns_cap_data);
 508         nscap = kmalloc(newsize, GFP_ATOMIC);
 509         if (!nscap)
 510                 return -ENOMEM;
 511         nscap->rootid = cpu_to_le32(nsrootid);
 512         nsmagic = VFS_CAP_REVISION_3;
 513         magic = le32_to_cpu(cap->magic_etc);
 514         if (magic & VFS_CAP_FLAGS_EFFECTIVE)
 515                 nsmagic |= VFS_CAP_FLAGS_EFFECTIVE;
 516         nscap->magic_etc = cpu_to_le32(nsmagic);
 517         memcpy(&nscap->data, &cap->data, sizeof(__le32) * 2 * VFS_CAP_U32);
 518 
 519         kvfree(*ivalue);
 520         *ivalue = nscap;
 521         return newsize;
 522 }
 523 
 524 /*
 525  * Calculate the new process capability sets from the capability sets attached
 526  * to a file.
 527  */
 528 static inline int bprm_caps_from_vfs_caps(struct cpu_vfs_cap_data *caps,
 529                                           struct linux_binprm *bprm,
 530                                           bool *effective,
 531                                           bool *has_fcap)
 532 {
 533         struct cred *new = bprm->cred;
 534         unsigned i;
 535         int ret = 0;
 536 
 537         if (caps->magic_etc & VFS_CAP_FLAGS_EFFECTIVE)
 538                 *effective = true;
 539 
 540         if (caps->magic_etc & VFS_CAP_REVISION_MASK)
 541                 *has_fcap = true;
 542 
 543         CAP_FOR_EACH_U32(i) {
 544                 __u32 permitted = caps->permitted.cap[i];
 545                 __u32 inheritable = caps->inheritable.cap[i];
 546 
 547                 /*
 548                  * pP' = (X & fP) | (pI & fI)
 549                  * The addition of pA' is handled later.
 550                  */
 551                 new->cap_permitted.cap[i] =
 552                         (new->cap_bset.cap[i] & permitted) |
 553                         (new->cap_inheritable.cap[i] & inheritable);
 554 
 555                 if (permitted & ~new->cap_permitted.cap[i])
 556                         /* insufficient to execute correctly */
 557                         ret = -EPERM;
 558         }
 559 
 560         /*
 561          * For legacy apps, with no internal support for recognizing they
 562          * do not have enough capabilities, we return an error if they are
 563          * missing some "forced" (aka file-permitted) capabilities.
 564          */
 565         return *effective ? ret : 0;
 566 }
 567 
 568 /*
 569  * Extract the on-exec-apply capability sets for an executable file.
 570  */
 571 int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data *cpu_caps)
 572 {
 573         struct inode *inode = d_backing_inode(dentry);
 574         __u32 magic_etc;
 575         unsigned tocopy, i;
 576         int size;
 577         struct vfs_ns_cap_data data, *nscaps = &data;
 578         struct vfs_cap_data *caps = (struct vfs_cap_data *) &data;
 579         kuid_t rootkuid;
 580         struct user_namespace *fs_ns;
 581 
 582         memset(cpu_caps, 0, sizeof(struct cpu_vfs_cap_data));
 583 
 584         if (!inode)
 585                 return -ENODATA;
 586 
 587         fs_ns = inode->i_sb->s_user_ns;
 588         size = __vfs_getxattr((struct dentry *)dentry, inode,
 589                               XATTR_NAME_CAPS, &data, XATTR_CAPS_SZ);
 590         if (size == -ENODATA || size == -EOPNOTSUPP)
 591                 /* no data, that's ok */
 592                 return -ENODATA;
 593 
 594         if (size < 0)
 595                 return size;
 596 
 597         if (size < sizeof(magic_etc))
 598                 return -EINVAL;
 599 
 600         cpu_caps->magic_etc = magic_etc = le32_to_cpu(caps->magic_etc);
 601 
 602         rootkuid = make_kuid(fs_ns, 0);
 603         switch (magic_etc & VFS_CAP_REVISION_MASK) {
 604         case VFS_CAP_REVISION_1:
 605                 if (size != XATTR_CAPS_SZ_1)
 606                         return -EINVAL;
 607                 tocopy = VFS_CAP_U32_1;
 608                 break;
 609         case VFS_CAP_REVISION_2:
 610                 if (size != XATTR_CAPS_SZ_2)
 611                         return -EINVAL;
 612                 tocopy = VFS_CAP_U32_2;
 613                 break;
 614         case VFS_CAP_REVISION_3:
 615                 if (size != XATTR_CAPS_SZ_3)
 616                         return -EINVAL;
 617                 tocopy = VFS_CAP_U32_3;
 618                 rootkuid = make_kuid(fs_ns, le32_to_cpu(nscaps->rootid));
 619                 break;
 620 
 621         default:
 622                 return -EINVAL;
 623         }
 624         /* Limit the caps to the mounter of the filesystem
 625          * or the more limited uid specified in the xattr.
 626          */
 627         if (!rootid_owns_currentns(rootkuid))
 628                 return -ENODATA;
 629 
 630         CAP_FOR_EACH_U32(i) {
 631                 if (i >= tocopy)
 632                         break;
 633                 cpu_caps->permitted.cap[i] = le32_to_cpu(caps->data[i].permitted);
 634                 cpu_caps->inheritable.cap[i] = le32_to_cpu(caps->data[i].inheritable);
 635         }
 636 
 637         cpu_caps->permitted.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK;
 638         cpu_caps->inheritable.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK;
 639 
 640         cpu_caps->rootid = rootkuid;
 641 
 642         return 0;
 643 }
 644 
 645 /*
 646  * Attempt to get the on-exec apply capability sets for an executable file from
 647  * its xattrs and, if present, apply them to the proposed credentials being
 648  * constructed by execve().
 649  */
 650 static int get_file_caps(struct linux_binprm *bprm, bool *effective, bool *has_fcap)
 651 {
 652         int rc = 0;
 653         struct cpu_vfs_cap_data vcaps;
 654 
 655         cap_clear(bprm->cred->cap_permitted);
 656 
 657         if (!file_caps_enabled)
 658                 return 0;
 659 
 660         if (!mnt_may_suid(bprm->file->f_path.mnt))
 661                 return 0;
 662 
 663         /*
 664          * This check is redundant with mnt_may_suid() but is kept to make
 665          * explicit that capability bits are limited to s_user_ns and its
 666          * descendants.
 667          */
 668         if (!current_in_userns(bprm->file->f_path.mnt->mnt_sb->s_user_ns))
 669                 return 0;
 670 
 671         rc = get_vfs_caps_from_disk(bprm->file->f_path.dentry, &vcaps);
 672         if (rc < 0) {
 673                 if (rc == -EINVAL)
 674                         printk(KERN_NOTICE "Invalid argument reading file caps for %s\n",
 675                                         bprm->filename);
 676                 else if (rc == -ENODATA)
 677                         rc = 0;
 678                 goto out;
 679         }
 680 
 681         rc = bprm_caps_from_vfs_caps(&vcaps, bprm, effective, has_fcap);
 682 
 683 out:
 684         if (rc)
 685                 cap_clear(bprm->cred->cap_permitted);
 686 
 687         return rc;
 688 }
 689 
 690 static inline bool root_privileged(void) { return !issecure(SECURE_NOROOT); }
 691 
 692 static inline bool __is_real(kuid_t uid, struct cred *cred)
 693 { return uid_eq(cred->uid, uid); }
 694 
 695 static inline bool __is_eff(kuid_t uid, struct cred *cred)
 696 { return uid_eq(cred->euid, uid); }
 697 
 698 static inline bool __is_suid(kuid_t uid, struct cred *cred)
 699 { return !__is_real(uid, cred) && __is_eff(uid, cred); }
 700 
 701 /*
 702  * handle_privileged_root - Handle case of privileged root
 703  * @bprm: The execution parameters, including the proposed creds
 704  * @has_fcap: Are any file capabilities set?
 705  * @effective: Do we have effective root privilege?
 706  * @root_uid: This namespace' root UID WRT initial USER namespace
 707  *
 708  * Handle the case where root is privileged and hasn't been neutered by
 709  * SECURE_NOROOT.  If file capabilities are set, they won't be combined with
 710  * set UID root and nothing is changed.  If we are root, cap_permitted is
 711  * updated.  If we have become set UID root, the effective bit is set.
 712  */
 713 static void handle_privileged_root(struct linux_binprm *bprm, bool has_fcap,
 714                                    bool *effective, kuid_t root_uid)
 715 {
 716         const struct cred *old = current_cred();
 717         struct cred *new = bprm->cred;
 718 
 719         if (!root_privileged())
 720                 return;
 721         /*
 722          * If the legacy file capability is set, then don't set privs
 723          * for a setuid root binary run by a non-root user.  Do set it
 724          * for a root user just to cause least surprise to an admin.
 725          */
 726         if (has_fcap && __is_suid(root_uid, new)) {
 727                 warn_setuid_and_fcaps_mixed(bprm->filename);
 728                 return;
 729         }
 730         /*
 731          * To support inheritance of root-permissions and suid-root
 732          * executables under compatibility mode, we override the
 733          * capability sets for the file.
 734          */
 735         if (__is_eff(root_uid, new) || __is_real(root_uid, new)) {
 736                 /* pP' = (cap_bset & ~0) | (pI & ~0) */
 737                 new->cap_permitted = cap_combine(old->cap_bset,
 738                                                  old->cap_inheritable);
 739         }
 740         /*
 741          * If only the real uid is 0, we do not set the effective bit.
 742          */
 743         if (__is_eff(root_uid, new))
 744                 *effective = true;
 745 }
 746 
 747 #define __cap_gained(field, target, source) \
 748         !cap_issubset(target->cap_##field, source->cap_##field)
 749 #define __cap_grew(target, source, cred) \
 750         !cap_issubset(cred->cap_##target, cred->cap_##source)
 751 #define __cap_full(field, cred) \
 752         cap_issubset(CAP_FULL_SET, cred->cap_##field)
 753 
 754 static inline bool __is_setuid(struct cred *new, const struct cred *old)
 755 { return !uid_eq(new->euid, old->uid); }
 756 
 757 static inline bool __is_setgid(struct cred *new, const struct cred *old)
 758 { return !gid_eq(new->egid, old->gid); }
 759 
 760 /*
 761  * 1) Audit candidate if current->cap_effective is set
 762  *
 763  * We do not bother to audit if 3 things are true:
 764  *   1) cap_effective has all caps
 765  *   2) we became root *OR* are were already root
 766  *   3) root is supposed to have all caps (SECURE_NOROOT)
 767  * Since this is just a normal root execing a process.
 768  *
 769  * Number 1 above might fail if you don't have a full bset, but I think
 770  * that is interesting information to audit.
 771  *
 772  * A number of other conditions require logging:
 773  * 2) something prevented setuid root getting all caps
 774  * 3) non-setuid root gets fcaps
 775  * 4) non-setuid root gets ambient
 776  */
 777 static inline bool nonroot_raised_pE(struct cred *new, const struct cred *old,
 778                                      kuid_t root, bool has_fcap)
 779 {
 780         bool ret = false;
 781 
 782         if ((__cap_grew(effective, ambient, new) &&
 783              !(__cap_full(effective, new) &&
 784                (__is_eff(root, new) || __is_real(root, new)) &&
 785                root_privileged())) ||
 786             (root_privileged() &&
 787              __is_suid(root, new) &&
 788              !__cap_full(effective, new)) ||
 789             (!__is_setuid(new, old) &&
 790              ((has_fcap &&
 791                __cap_gained(permitted, new, old)) ||
 792               __cap_gained(ambient, new, old))))
 793 
 794                 ret = true;
 795 
 796         return ret;
 797 }
 798 
 799 /**
 800  * cap_bprm_set_creds - Set up the proposed credentials for execve().
 801  * @bprm: The execution parameters, including the proposed creds
 802  *
 803  * Set up the proposed credentials for a new execution context being
 804  * constructed by execve().  The proposed creds in @bprm->cred is altered,
 805  * which won't take effect immediately.  Returns 0 if successful, -ve on error.
 806  */
 807 int cap_bprm_set_creds(struct linux_binprm *bprm)
 808 {
 809         const struct cred *old = current_cred();
 810         struct cred *new = bprm->cred;
 811         bool effective = false, has_fcap = false, is_setid;
 812         int ret;
 813         kuid_t root_uid;
 814 
 815         new->cap_ambient = old->cap_ambient;
 816         if (WARN_ON(!cap_ambient_invariant_ok(old)))
 817                 return -EPERM;
 818 
 819         ret = get_file_caps(bprm, &effective, &has_fcap);
 820         if (ret < 0)
 821                 return ret;
 822 
 823         root_uid = make_kuid(new->user_ns, 0);
 824 
 825         handle_privileged_root(bprm, has_fcap, &effective, root_uid);
 826 
 827         /* if we have fs caps, clear dangerous personality flags */
 828         if (__cap_gained(permitted, new, old))
 829                 bprm->per_clear |= PER_CLEAR_ON_SETID;
 830 
 831         /* Don't let someone trace a set[ug]id/setpcap binary with the revised
 832          * credentials unless they have the appropriate permit.
 833          *
 834          * In addition, if NO_NEW_PRIVS, then ensure we get no new privs.
 835          */
 836         is_setid = __is_setuid(new, old) || __is_setgid(new, old);
 837 
 838         if ((is_setid || __cap_gained(permitted, new, old)) &&
 839             ((bprm->unsafe & ~LSM_UNSAFE_PTRACE) ||
 840              !ptracer_capable(current, new->user_ns))) {
 841                 /* downgrade; they get no more than they had, and maybe less */
 842                 if (!ns_capable(new->user_ns, CAP_SETUID) ||
 843                     (bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS)) {
 844                         new->euid = new->uid;
 845                         new->egid = new->gid;
 846                 }
 847                 new->cap_permitted = cap_intersect(new->cap_permitted,
 848                                                    old->cap_permitted);
 849         }
 850 
 851         new->suid = new->fsuid = new->euid;
 852         new->sgid = new->fsgid = new->egid;
 853 
 854         /* File caps or setid cancels ambient. */
 855         if (has_fcap || is_setid)
 856                 cap_clear(new->cap_ambient);
 857 
 858         /*
 859          * Now that we've computed pA', update pP' to give:
 860          *   pP' = (X & fP) | (pI & fI) | pA'
 861          */
 862         new->cap_permitted = cap_combine(new->cap_permitted, new->cap_ambient);
 863 
 864         /*
 865          * Set pE' = (fE ? pP' : pA').  Because pA' is zero if fE is set,
 866          * this is the same as pE' = (fE ? pP' : 0) | pA'.
 867          */
 868         if (effective)
 869                 new->cap_effective = new->cap_permitted;
 870         else
 871                 new->cap_effective = new->cap_ambient;
 872 
 873         if (WARN_ON(!cap_ambient_invariant_ok(new)))
 874                 return -EPERM;
 875 
 876         if (nonroot_raised_pE(new, old, root_uid, has_fcap)) {
 877                 ret = audit_log_bprm_fcaps(bprm, new, old);
 878                 if (ret < 0)
 879                         return ret;
 880         }
 881 
 882         new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);
 883 
 884         if (WARN_ON(!cap_ambient_invariant_ok(new)))
 885                 return -EPERM;
 886 
 887         /* Check for privilege-elevated exec. */
 888         bprm->cap_elevated = 0;
 889         if (is_setid ||
 890             (!__is_real(root_uid, new) &&
 891              (effective ||
 892               __cap_grew(permitted, ambient, new))))
 893                 bprm->cap_elevated = 1;
 894 
 895         return 0;
 896 }
 897 
 898 /**
 899  * cap_inode_setxattr - Determine whether an xattr may be altered
 900  * @dentry: The inode/dentry being altered
 901  * @name: The name of the xattr to be changed
 902  * @value: The value that the xattr will be changed to
 903  * @size: The size of value
 904  * @flags: The replacement flag
 905  *
 906  * Determine whether an xattr may be altered or set on an inode, returning 0 if
 907  * permission is granted, -ve if denied.
 908  *
 909  * This is used to make sure security xattrs don't get updated or set by those
 910  * who aren't privileged to do so.
 911  */
 912 int cap_inode_setxattr(struct dentry *dentry, const char *name,
 913                        const void *value, size_t size, int flags)
 914 {
 915         struct user_namespace *user_ns = dentry->d_sb->s_user_ns;
 916 
 917         /* Ignore non-security xattrs */
 918         if (strncmp(name, XATTR_SECURITY_PREFIX,
 919                         XATTR_SECURITY_PREFIX_LEN) != 0)
 920                 return 0;
 921 
 922         /*
 923          * For XATTR_NAME_CAPS the check will be done in
 924          * cap_convert_nscap(), called by setxattr()
 925          */
 926         if (strcmp(name, XATTR_NAME_CAPS) == 0)
 927                 return 0;
 928 
 929         if (!ns_capable(user_ns, CAP_SYS_ADMIN))
 930                 return -EPERM;
 931         return 0;
 932 }
 933 
 934 /**
 935  * cap_inode_removexattr - Determine whether an xattr may be removed
 936  * @dentry: The inode/dentry being altered
 937  * @name: The name of the xattr to be changed
 938  *
 939  * Determine whether an xattr may be removed from an inode, returning 0 if
 940  * permission is granted, -ve if denied.
 941  *
 942  * This is used to make sure security xattrs don't get removed by those who
 943  * aren't privileged to remove them.
 944  */
 945 int cap_inode_removexattr(struct dentry *dentry, const char *name)
 946 {
 947         struct user_namespace *user_ns = dentry->d_sb->s_user_ns;
 948 
 949         /* Ignore non-security xattrs */
 950         if (strncmp(name, XATTR_SECURITY_PREFIX,
 951                         XATTR_SECURITY_PREFIX_LEN) != 0)
 952                 return 0;
 953 
 954         if (strcmp(name, XATTR_NAME_CAPS) == 0) {
 955                 /* security.capability gets namespaced */
 956                 struct inode *inode = d_backing_inode(dentry);
 957                 if (!inode)
 958                         return -EINVAL;
 959                 if (!capable_wrt_inode_uidgid(inode, CAP_SETFCAP))
 960                         return -EPERM;
 961                 return 0;
 962         }
 963 
 964         if (!ns_capable(user_ns, CAP_SYS_ADMIN))
 965                 return -EPERM;
 966         return 0;
 967 }
 968 
 969 /*
 970  * cap_emulate_setxuid() fixes the effective / permitted capabilities of
 971  * a process after a call to setuid, setreuid, or setresuid.
 972  *
 973  *  1) When set*uiding _from_ one of {r,e,s}uid == 0 _to_ all of
 974  *  {r,e,s}uid != 0, the permitted and effective capabilities are
 975  *  cleared.
 976  *
 977  *  2) When set*uiding _from_ euid == 0 _to_ euid != 0, the effective
 978  *  capabilities of the process are cleared.
 979  *
 980  *  3) When set*uiding _from_ euid != 0 _to_ euid == 0, the effective
 981  *  capabilities are set to the permitted capabilities.
 982  *
 983  *  fsuid is handled elsewhere. fsuid == 0 and {r,e,s}uid!= 0 should
 984  *  never happen.
 985  *
 986  *  -astor
 987  *
 988  * cevans - New behaviour, Oct '99
 989  * A process may, via prctl(), elect to keep its capabilities when it
 990  * calls setuid() and switches away from uid==0. Both permitted and
 991  * effective sets will be retained.
 992  * Without this change, it was impossible for a daemon to drop only some
 993  * of its privilege. The call to setuid(!=0) would drop all privileges!
 994  * Keeping uid 0 is not an option because uid 0 owns too many vital
 995  * files..
 996  * Thanks to Olaf Kirch and Peter Benie for spotting this.
 997  */
 998 static inline void cap_emulate_setxuid(struct cred *new, const struct cred *old)
 999 {
1000         kuid_t root_uid = make_kuid(old->user_ns, 0);
1001 
1002         if ((uid_eq(old->uid, root_uid) ||
1003              uid_eq(old->euid, root_uid) ||
1004              uid_eq(old->suid, root_uid)) &&
1005             (!uid_eq(new->uid, root_uid) &&
1006              !uid_eq(new->euid, root_uid) &&
1007              !uid_eq(new->suid, root_uid))) {
1008                 if (!issecure(SECURE_KEEP_CAPS)) {
1009                         cap_clear(new->cap_permitted);
1010                         cap_clear(new->cap_effective);
1011                 }
1012 
1013                 /*
1014                  * Pre-ambient programs expect setresuid to nonroot followed
1015                  * by exec to drop capabilities.  We should make sure that
1016                  * this remains the case.
1017                  */
1018                 cap_clear(new->cap_ambient);
1019         }
1020         if (uid_eq(old->euid, root_uid) && !uid_eq(new->euid, root_uid))
1021                 cap_clear(new->cap_effective);
1022         if (!uid_eq(old->euid, root_uid) && uid_eq(new->euid, root_uid))
1023                 new->cap_effective = new->cap_permitted;
1024 }
1025 
1026 /**
1027  * cap_task_fix_setuid - Fix up the results of setuid() call
1028  * @new: The proposed credentials
1029  * @old: The current task's current credentials
1030  * @flags: Indications of what has changed
1031  *
1032  * Fix up the results of setuid() call before the credential changes are
1033  * actually applied, returning 0 to grant the changes, -ve to deny them.
1034  */
1035 int cap_task_fix_setuid(struct cred *new, const struct cred *old, int flags)
1036 {
1037         switch (flags) {
1038         case LSM_SETID_RE:
1039         case LSM_SETID_ID:
1040         case LSM_SETID_RES:
1041                 /* juggle the capabilities to follow [RES]UID changes unless
1042                  * otherwise suppressed */
1043                 if (!issecure(SECURE_NO_SETUID_FIXUP))
1044                         cap_emulate_setxuid(new, old);
1045                 break;
1046 
1047         case LSM_SETID_FS:
1048                 /* juggle the capabilties to follow FSUID changes, unless
1049                  * otherwise suppressed
1050                  *
1051                  * FIXME - is fsuser used for all CAP_FS_MASK capabilities?
1052                  *          if not, we might be a bit too harsh here.
1053                  */
1054                 if (!issecure(SECURE_NO_SETUID_FIXUP)) {
1055                         kuid_t root_uid = make_kuid(old->user_ns, 0);
1056                         if (uid_eq(old->fsuid, root_uid) && !uid_eq(new->fsuid, root_uid))
1057                                 new->cap_effective =
1058                                         cap_drop_fs_set(new->cap_effective);
1059 
1060                         if (!uid_eq(old->fsuid, root_uid) && uid_eq(new->fsuid, root_uid))
1061                                 new->cap_effective =
1062                                         cap_raise_fs_set(new->cap_effective,
1063                                                          new->cap_permitted);
1064                 }
1065                 break;
1066 
1067         default:
1068                 return -EINVAL;
1069         }
1070 
1071         return 0;
1072 }
1073 
1074 /*
1075  * Rationale: code calling task_setscheduler, task_setioprio, and
1076  * task_setnice, assumes that
1077  *   . if capable(cap_sys_nice), then those actions should be allowed
1078  *   . if not capable(cap_sys_nice), but acting on your own processes,
1079  *      then those actions should be allowed
1080  * This is insufficient now since you can call code without suid, but
1081  * yet with increased caps.
1082  * So we check for increased caps on the target process.
1083  */
1084 static int cap_safe_nice(struct task_struct *p)
1085 {
1086         int is_subset, ret = 0;
1087 
1088         rcu_read_lock();
1089         is_subset = cap_issubset(__task_cred(p)->cap_permitted,
1090                                  current_cred()->cap_permitted);
1091         if (!is_subset && !ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE))
1092                 ret = -EPERM;
1093         rcu_read_unlock();
1094 
1095         return ret;
1096 }
1097 
1098 /**
1099  * cap_task_setscheduler - Detemine if scheduler policy change is permitted
1100  * @p: The task to affect
1101  *
1102  * Detemine if the requested scheduler policy change is permitted for the
1103  * specified task, returning 0 if permission is granted, -ve if denied.
1104  */
1105 int cap_task_setscheduler(struct task_struct *p)
1106 {
1107         return cap_safe_nice(p);
1108 }
1109 
1110 /**
1111  * cap_task_ioprio - Detemine if I/O priority change is permitted
1112  * @p: The task to affect
1113  * @ioprio: The I/O priority to set
1114  *
1115  * Detemine if the requested I/O priority change is permitted for the specified
1116  * task, returning 0 if permission is granted, -ve if denied.
1117  */
1118 int cap_task_setioprio(struct task_struct *p, int ioprio)
1119 {
1120         return cap_safe_nice(p);
1121 }
1122 
1123 /**
1124  * cap_task_ioprio - Detemine if task priority change is permitted
1125  * @p: The task to affect
1126  * @nice: The nice value to set
1127  *
1128  * Detemine if the requested task priority change is permitted for the
1129  * specified task, returning 0 if permission is granted, -ve if denied.
1130  */
1131 int cap_task_setnice(struct task_struct *p, int nice)
1132 {
1133         return cap_safe_nice(p);
1134 }
1135 
1136 /*
1137  * Implement PR_CAPBSET_DROP.  Attempt to remove the specified capability from
1138  * the current task's bounding set.  Returns 0 on success, -ve on error.
1139  */
1140 static int cap_prctl_drop(unsigned long cap)
1141 {
1142         struct cred *new;
1143 
1144         if (!ns_capable(current_user_ns(), CAP_SETPCAP))
1145                 return -EPERM;
1146         if (!cap_valid(cap))
1147                 return -EINVAL;
1148 
1149         new = prepare_creds();
1150         if (!new)
1151                 return -ENOMEM;
1152         cap_lower(new->cap_bset, cap);
1153         return commit_creds(new);
1154 }
1155 
1156 /**
1157  * cap_task_prctl - Implement process control functions for this security module
1158  * @option: The process control function requested
1159  * @arg2, @arg3, @arg4, @arg5: The argument data for this function
1160  *
1161  * Allow process control functions (sys_prctl()) to alter capabilities; may
1162  * also deny access to other functions not otherwise implemented here.
1163  *
1164  * Returns 0 or +ve on success, -ENOSYS if this function is not implemented
1165  * here, other -ve on error.  If -ENOSYS is returned, sys_prctl() and other LSM
1166  * modules will consider performing the function.
1167  */
1168 int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3,
1169                    unsigned long arg4, unsigned long arg5)
1170 {
1171         const struct cred *old = current_cred();
1172         struct cred *new;
1173 
1174         switch (option) {
1175         case PR_CAPBSET_READ:
1176                 if (!cap_valid(arg2))
1177                         return -EINVAL;
1178                 return !!cap_raised(old->cap_bset, arg2);
1179 
1180         case PR_CAPBSET_DROP:
1181                 return cap_prctl_drop(arg2);
1182 
1183         /*
1184          * The next four prctl's remain to assist with transitioning a
1185          * system from legacy UID=0 based privilege (when filesystem
1186          * capabilities are not in use) to a system using filesystem
1187          * capabilities only - as the POSIX.1e draft intended.
1188          *
1189          * Note:
1190          *
1191          *  PR_SET_SECUREBITS =
1192          *      issecure_mask(SECURE_KEEP_CAPS_LOCKED)
1193          *    | issecure_mask(SECURE_NOROOT)
1194          *    | issecure_mask(SECURE_NOROOT_LOCKED)
1195          *    | issecure_mask(SECURE_NO_SETUID_FIXUP)
1196          *    | issecure_mask(SECURE_NO_SETUID_FIXUP_LOCKED)
1197          *
1198          * will ensure that the current process and all of its
1199          * children will be locked into a pure
1200          * capability-based-privilege environment.
1201          */
1202         case PR_SET_SECUREBITS:
1203                 if ((((old->securebits & SECURE_ALL_LOCKS) >> 1)
1204                      & (old->securebits ^ arg2))                        /*[1]*/
1205                     || ((old->securebits & SECURE_ALL_LOCKS & ~arg2))   /*[2]*/
1206                     || (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS))   /*[3]*/
1207                     || (cap_capable(current_cred(),
1208                                     current_cred()->user_ns,
1209                                     CAP_SETPCAP,
1210                                     CAP_OPT_NONE) != 0)                 /*[4]*/
1211                         /*
1212                          * [1] no changing of bits that are locked
1213                          * [2] no unlocking of locks
1214                          * [3] no setting of unsupported bits
1215                          * [4] doing anything requires privilege (go read about
1216                          *     the "sendmail capabilities bug")
1217                          */
1218                     )
1219                         /* cannot change a locked bit */
1220                         return -EPERM;
1221 
1222                 new = prepare_creds();
1223                 if (!new)
1224                         return -ENOMEM;
1225                 new->securebits = arg2;
1226                 return commit_creds(new);
1227 
1228         case PR_GET_SECUREBITS:
1229                 return old->securebits;
1230 
1231         case PR_GET_KEEPCAPS:
1232                 return !!issecure(SECURE_KEEP_CAPS);
1233 
1234         case PR_SET_KEEPCAPS:
1235                 if (arg2 > 1) /* Note, we rely on arg2 being unsigned here */
1236                         return -EINVAL;
1237                 if (issecure(SECURE_KEEP_CAPS_LOCKED))
1238                         return -EPERM;
1239 
1240                 new = prepare_creds();
1241                 if (!new)
1242                         return -ENOMEM;
1243                 if (arg2)
1244                         new->securebits |= issecure_mask(SECURE_KEEP_CAPS);
1245                 else
1246                         new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);
1247                 return commit_creds(new);
1248 
1249         case PR_CAP_AMBIENT:
1250                 if (arg2 == PR_CAP_AMBIENT_CLEAR_ALL) {
1251                         if (arg3 | arg4 | arg5)
1252                                 return -EINVAL;
1253 
1254                         new = prepare_creds();
1255                         if (!new)
1256                                 return -ENOMEM;
1257                         cap_clear(new->cap_ambient);
1258                         return commit_creds(new);
1259                 }
1260 
1261                 if (((!cap_valid(arg3)) | arg4 | arg5))
1262                         return -EINVAL;
1263 
1264                 if (arg2 == PR_CAP_AMBIENT_IS_SET) {
1265                         return !!cap_raised(current_cred()->cap_ambient, arg3);
1266                 } else if (arg2 != PR_CAP_AMBIENT_RAISE &&
1267                            arg2 != PR_CAP_AMBIENT_LOWER) {
1268                         return -EINVAL;
1269                 } else {
1270                         if (arg2 == PR_CAP_AMBIENT_RAISE &&
1271                             (!cap_raised(current_cred()->cap_permitted, arg3) ||
1272                              !cap_raised(current_cred()->cap_inheritable,
1273                                          arg3) ||
1274                              issecure(SECURE_NO_CAP_AMBIENT_RAISE)))
1275                                 return -EPERM;
1276 
1277                         new = prepare_creds();
1278                         if (!new)
1279                                 return -ENOMEM;
1280                         if (arg2 == PR_CAP_AMBIENT_RAISE)
1281                                 cap_raise(new->cap_ambient, arg3);
1282                         else
1283                                 cap_lower(new->cap_ambient, arg3);
1284                         return commit_creds(new);
1285                 }
1286 
1287         default:
1288                 /* No functionality available - continue with default */
1289                 return -ENOSYS;
1290         }
1291 }
1292 
1293 /**
1294  * cap_vm_enough_memory - Determine whether a new virtual mapping is permitted
1295  * @mm: The VM space in which the new mapping is to be made
1296  * @pages: The size of the mapping
1297  *
1298  * Determine whether the allocation of a new virtual mapping by the current
1299  * task is permitted, returning 1 if permission is granted, 0 if not.
1300  */
1301 int cap_vm_enough_memory(struct mm_struct *mm, long pages)
1302 {
1303         int cap_sys_admin = 0;
1304 
1305         if (cap_capable(current_cred(), &init_user_ns,
1306                                 CAP_SYS_ADMIN, CAP_OPT_NOAUDIT) == 0)
1307                 cap_sys_admin = 1;
1308 
1309         return cap_sys_admin;
1310 }
1311 
1312 /*
1313  * cap_mmap_addr - check if able to map given addr
1314  * @addr: address attempting to be mapped
1315  *
1316  * If the process is attempting to map memory below dac_mmap_min_addr they need
1317  * CAP_SYS_RAWIO.  The other parameters to this function are unused by the
1318  * capability security module.  Returns 0 if this mapping should be allowed
1319  * -EPERM if not.
1320  */
1321 int cap_mmap_addr(unsigned long addr)
1322 {
1323         int ret = 0;
1324 
1325         if (addr < dac_mmap_min_addr) {
1326                 ret = cap_capable(current_cred(), &init_user_ns, CAP_SYS_RAWIO,
1327                                   CAP_OPT_NONE);
1328                 /* set PF_SUPERPRIV if it turns out we allow the low mmap */
1329                 if (ret == 0)
1330                         current->flags |= PF_SUPERPRIV;
1331         }
1332         return ret;
1333 }
1334 
1335 int cap_mmap_file(struct file *file, unsigned long reqprot,
1336                   unsigned long prot, unsigned long flags)
1337 {
1338         return 0;
1339 }
1340 
1341 #ifdef CONFIG_SECURITY
1342 
1343 static struct security_hook_list capability_hooks[] __lsm_ro_after_init = {
1344         LSM_HOOK_INIT(capable, cap_capable),
1345         LSM_HOOK_INIT(settime, cap_settime),
1346         LSM_HOOK_INIT(ptrace_access_check, cap_ptrace_access_check),
1347         LSM_HOOK_INIT(ptrace_traceme, cap_ptrace_traceme),
1348         LSM_HOOK_INIT(capget, cap_capget),
1349         LSM_HOOK_INIT(capset, cap_capset),
1350         LSM_HOOK_INIT(bprm_set_creds, cap_bprm_set_creds),
1351         LSM_HOOK_INIT(inode_need_killpriv, cap_inode_need_killpriv),
1352         LSM_HOOK_INIT(inode_killpriv, cap_inode_killpriv),
1353         LSM_HOOK_INIT(inode_getsecurity, cap_inode_getsecurity),
1354         LSM_HOOK_INIT(mmap_addr, cap_mmap_addr),
1355         LSM_HOOK_INIT(mmap_file, cap_mmap_file),
1356         LSM_HOOK_INIT(task_fix_setuid, cap_task_fix_setuid),
1357         LSM_HOOK_INIT(task_prctl, cap_task_prctl),
1358         LSM_HOOK_INIT(task_setscheduler, cap_task_setscheduler),
1359         LSM_HOOK_INIT(task_setioprio, cap_task_setioprio),
1360         LSM_HOOK_INIT(task_setnice, cap_task_setnice),
1361         LSM_HOOK_INIT(vm_enough_memory, cap_vm_enough_memory),
1362 };
1363 
1364 static int __init capability_init(void)
1365 {
1366         security_add_hooks(capability_hooks, ARRAY_SIZE(capability_hooks),
1367                                 "capability");
1368         return 0;
1369 }
1370 
1371 DEFINE_LSM(capability) = {
1372         .name = "capability",
1373         .order = LSM_ORDER_FIRST,
1374         .init = capability_init,
1375 };
1376 
1377 #endif /* CONFIG_SECURITY */
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root/security/commoncap.c

DEFINITIONS
