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 */
  39static 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 */
  65int 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 */
 111int 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 */
 133int 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;
 152out:
 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 */
 170int 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;
 184out:
 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 */
 199int 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 */
 218static 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 */
 241int 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 */
 295int 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 */
 312int 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
 322static 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
 339static __u32 sansflags(__u32 m)
 340{
 341	return m & ~VFS_CAP_FLAGS_EFFECTIVE;
 342}
 343
 344static 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
 351static 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 */
 369int 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
 453static 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
 465static 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 */
 476int 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 */
 528static 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 */
 571int 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 */
 650static 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
 683out:
 
 684	if (rc)
 685		cap_clear(bprm->cred->cap_permitted);
 686
 687	return rc;
 688}
 689
 690static inline bool root_privileged(void) { return !issecure(SECURE_NOROOT); }
 691
 692static inline bool __is_real(kuid_t uid, struct cred *cred)
 693{ return uid_eq(cred->uid, uid); }
 694
 695static inline bool __is_eff(kuid_t uid, struct cred *cred)
 696{ return uid_eq(cred->euid, uid); }
 697
 698static 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 */
 713static 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
 754static inline bool __is_setuid(struct cred *new, const struct cred *old)
 755{ return !uid_eq(new->euid, old->uid); }
 756
 757static 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 */
 777static 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 */
 807int 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	if (WARN_ON(!cap_ambient_invariant_ok(old)))
 816		return -EPERM;
 817
 818	ret = get_file_caps(bprm, &effective, &has_fcap);
 819	if (ret < 0)
 820		return ret;
 821
 822	root_uid = make_kuid(new->user_ns, 0);
 823
 824	handle_privileged_root(bprm, has_fcap, &effective, root_uid);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 825
 826	/* if we have fs caps, clear dangerous personality flags */
 827	if (__cap_gained(permitted, new, old))
 828		bprm->per_clear |= PER_CLEAR_ON_SETID;
 829
 
 830	/* Don't let someone trace a set[ug]id/setpcap binary with the revised
 831	 * credentials unless they have the appropriate permit.
 832	 *
 833	 * In addition, if NO_NEW_PRIVS, then ensure we get no new privs.
 834	 */
 835	is_setid = __is_setuid(new, old) || __is_setgid(new, old);
 836
 837	if ((is_setid || __cap_gained(permitted, new, old)) &&
 838	    ((bprm->unsafe & ~LSM_UNSAFE_PTRACE) ||
 839	     !ptracer_capable(current, new->user_ns))) {
 840		/* downgrade; they get no more than they had, and maybe less */
 841		if (!ns_capable(new->user_ns, CAP_SETUID) ||
 842		    (bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS)) {
 843			new->euid = new->uid;
 844			new->egid = new->gid;
 845		}
 846		new->cap_permitted = cap_intersect(new->cap_permitted,
 847						   old->cap_permitted);
 848	}
 849
 850	new->suid = new->fsuid = new->euid;
 851	new->sgid = new->fsgid = new->egid;
 852
 853	/* File caps or setid cancels ambient. */
 854	if (has_fcap || is_setid)
 855		cap_clear(new->cap_ambient);
 856
 857	/*
 858	 * Now that we've computed pA', update pP' to give:
 859	 *   pP' = (X & fP) | (pI & fI) | pA'
 860	 */
 861	new->cap_permitted = cap_combine(new->cap_permitted, new->cap_ambient);
 862
 863	/*
 864	 * Set pE' = (fE ? pP' : pA').  Because pA' is zero if fE is set,
 865	 * this is the same as pE' = (fE ? pP' : 0) | pA'.
 866	 */
 867	if (effective)
 868		new->cap_effective = new->cap_permitted;
 869	else
 870		new->cap_effective = new->cap_ambient;
 871
 872	if (WARN_ON(!cap_ambient_invariant_ok(new)))
 873		return -EPERM;
 874
 875	if (nonroot_raised_pE(new, old, root_uid, has_fcap)) {
 876		ret = audit_log_bprm_fcaps(bprm, new, old);
 877		if (ret < 0)
 878			return ret;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 879	}
 880
 881	new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);
 
 
 882
 883	if (WARN_ON(!cap_ambient_invariant_ok(new)))
 884		return -EPERM;
 
 
 
 
 
 
 
 
 
 
 
 
 885
 886	/* Check for privilege-elevated exec. */
 887	bprm->cap_elevated = 0;
 888	if (is_setid ||
 889	    (!__is_real(root_uid, new) &&
 890	     (effective ||
 891	      __cap_grew(permitted, ambient, new))))
 892		bprm->cap_elevated = 1;
 893
 894	return 0;
 
 895}
 896
 897/**
 898 * cap_inode_setxattr - Determine whether an xattr may be altered
 899 * @dentry: The inode/dentry being altered
 900 * @name: The name of the xattr to be changed
 901 * @value: The value that the xattr will be changed to
 902 * @size: The size of value
 903 * @flags: The replacement flag
 904 *
 905 * Determine whether an xattr may be altered or set on an inode, returning 0 if
 906 * permission is granted, -ve if denied.
 907 *
 908 * This is used to make sure security xattrs don't get updated or set by those
 909 * who aren't privileged to do so.
 910 */
 911int cap_inode_setxattr(struct dentry *dentry, const char *name,
 912		       const void *value, size_t size, int flags)
 913{
 914	struct user_namespace *user_ns = dentry->d_sb->s_user_ns;
 915
 916	/* Ignore non-security xattrs */
 917	if (strncmp(name, XATTR_SECURITY_PREFIX,
 918			XATTR_SECURITY_PREFIX_LEN) != 0)
 919		return 0;
 920
 921	/*
 922	 * For XATTR_NAME_CAPS the check will be done in
 923	 * cap_convert_nscap(), called by setxattr()
 924	 */
 925	if (strcmp(name, XATTR_NAME_CAPS) == 0)
 926		return 0;
 
 927
 928	if (!ns_capable(user_ns, CAP_SYS_ADMIN))
 
 
 929		return -EPERM;
 930	return 0;
 931}
 932
 933/**
 934 * cap_inode_removexattr - Determine whether an xattr may be removed
 935 * @dentry: The inode/dentry being altered
 936 * @name: The name of the xattr to be changed
 937 *
 938 * Determine whether an xattr may be removed from an inode, returning 0 if
 939 * permission is granted, -ve if denied.
 940 *
 941 * This is used to make sure security xattrs don't get removed by those who
 942 * aren't privileged to remove them.
 943 */
 944int cap_inode_removexattr(struct dentry *dentry, const char *name)
 945{
 946	struct user_namespace *user_ns = dentry->d_sb->s_user_ns;
 947
 948	/* Ignore non-security xattrs */
 949	if (strncmp(name, XATTR_SECURITY_PREFIX,
 950			XATTR_SECURITY_PREFIX_LEN) != 0)
 951		return 0;
 952
 953	if (strcmp(name, XATTR_NAME_CAPS) == 0) {
 954		/* security.capability gets namespaced */
 955		struct inode *inode = d_backing_inode(dentry);
 956		if (!inode)
 957			return -EINVAL;
 958		if (!capable_wrt_inode_uidgid(inode, CAP_SETFCAP))
 959			return -EPERM;
 960		return 0;
 961	}
 962
 963	if (!ns_capable(user_ns, CAP_SYS_ADMIN))
 
 
 964		return -EPERM;
 965	return 0;
 966}
 967
 968/*
 969 * cap_emulate_setxuid() fixes the effective / permitted capabilities of
 970 * a process after a call to setuid, setreuid, or setresuid.
 971 *
 972 *  1) When set*uiding _from_ one of {r,e,s}uid == 0 _to_ all of
 973 *  {r,e,s}uid != 0, the permitted and effective capabilities are
 974 *  cleared.
 975 *
 976 *  2) When set*uiding _from_ euid == 0 _to_ euid != 0, the effective
 977 *  capabilities of the process are cleared.
 978 *
 979 *  3) When set*uiding _from_ euid != 0 _to_ euid == 0, the effective
 980 *  capabilities are set to the permitted capabilities.
 981 *
 982 *  fsuid is handled elsewhere. fsuid == 0 and {r,e,s}uid!= 0 should
 983 *  never happen.
 984 *
 985 *  -astor
 986 *
 987 * cevans - New behaviour, Oct '99
 988 * A process may, via prctl(), elect to keep its capabilities when it
 989 * calls setuid() and switches away from uid==0. Both permitted and
 990 * effective sets will be retained.
 991 * Without this change, it was impossible for a daemon to drop only some
 992 * of its privilege. The call to setuid(!=0) would drop all privileges!
 993 * Keeping uid 0 is not an option because uid 0 owns too many vital
 994 * files..
 995 * Thanks to Olaf Kirch and Peter Benie for spotting this.
 996 */
 997static inline void cap_emulate_setxuid(struct cred *new, const struct cred *old)
 998{
 999	kuid_t root_uid = make_kuid(old->user_ns, 0);
1000
1001	if ((uid_eq(old->uid, root_uid) ||
1002	     uid_eq(old->euid, root_uid) ||
1003	     uid_eq(old->suid, root_uid)) &&
1004	    (!uid_eq(new->uid, root_uid) &&
1005	     !uid_eq(new->euid, root_uid) &&
1006	     !uid_eq(new->suid, root_uid))) {
1007		if (!issecure(SECURE_KEEP_CAPS)) {
1008			cap_clear(new->cap_permitted);
1009			cap_clear(new->cap_effective);
1010		}
1011
1012		/*
1013		 * Pre-ambient programs expect setresuid to nonroot followed
1014		 * by exec to drop capabilities.  We should make sure that
1015		 * this remains the case.
1016		 */
1017		cap_clear(new->cap_ambient);
1018	}
1019	if (uid_eq(old->euid, root_uid) && !uid_eq(new->euid, root_uid))
1020		cap_clear(new->cap_effective);
1021	if (!uid_eq(old->euid, root_uid) && uid_eq(new->euid, root_uid))
1022		new->cap_effective = new->cap_permitted;
1023}
1024
1025/**
1026 * cap_task_fix_setuid - Fix up the results of setuid() call
1027 * @new: The proposed credentials
1028 * @old: The current task's current credentials
1029 * @flags: Indications of what has changed
1030 *
1031 * Fix up the results of setuid() call before the credential changes are
1032 * actually applied, returning 0 to grant the changes, -ve to deny them.
1033 */
1034int cap_task_fix_setuid(struct cred *new, const struct cred *old, int flags)
1035{
1036	switch (flags) {
1037	case LSM_SETID_RE:
1038	case LSM_SETID_ID:
1039	case LSM_SETID_RES:
1040		/* juggle the capabilities to follow [RES]UID changes unless
1041		 * otherwise suppressed */
1042		if (!issecure(SECURE_NO_SETUID_FIXUP))
1043			cap_emulate_setxuid(new, old);
1044		break;
1045
1046	case LSM_SETID_FS:
1047		/* juggle the capabilties to follow FSUID changes, unless
1048		 * otherwise suppressed
1049		 *
1050		 * FIXME - is fsuser used for all CAP_FS_MASK capabilities?
1051		 *          if not, we might be a bit too harsh here.
1052		 */
1053		if (!issecure(SECURE_NO_SETUID_FIXUP)) {
1054			kuid_t root_uid = make_kuid(old->user_ns, 0);
1055			if (uid_eq(old->fsuid, root_uid) && !uid_eq(new->fsuid, root_uid))
1056				new->cap_effective =
1057					cap_drop_fs_set(new->cap_effective);
1058
1059			if (!uid_eq(old->fsuid, root_uid) && uid_eq(new->fsuid, root_uid))
1060				new->cap_effective =
1061					cap_raise_fs_set(new->cap_effective,
1062							 new->cap_permitted);
1063		}
1064		break;
1065
1066	default:
1067		return -EINVAL;
1068	}
1069
1070	return 0;
1071}
1072
1073/*
1074 * Rationale: code calling task_setscheduler, task_setioprio, and
1075 * task_setnice, assumes that
1076 *   . if capable(cap_sys_nice), then those actions should be allowed
1077 *   . if not capable(cap_sys_nice), but acting on your own processes,
1078 *   	then those actions should be allowed
1079 * This is insufficient now since you can call code without suid, but
1080 * yet with increased caps.
1081 * So we check for increased caps on the target process.
1082 */
1083static int cap_safe_nice(struct task_struct *p)
1084{
1085	int is_subset, ret = 0;
1086
1087	rcu_read_lock();
1088	is_subset = cap_issubset(__task_cred(p)->cap_permitted,
1089				 current_cred()->cap_permitted);
1090	if (!is_subset && !ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE))
1091		ret = -EPERM;
1092	rcu_read_unlock();
1093
1094	return ret;
 
 
1095}
1096
1097/**
1098 * cap_task_setscheduler - Detemine if scheduler policy change is permitted
1099 * @p: The task to affect
1100 *
1101 * Detemine if the requested scheduler policy change is permitted for the
1102 * specified task, returning 0 if permission is granted, -ve if denied.
1103 */
1104int cap_task_setscheduler(struct task_struct *p)
1105{
1106	return cap_safe_nice(p);
1107}
1108
1109/**
1110 * cap_task_ioprio - Detemine if I/O priority change is permitted
1111 * @p: The task to affect
1112 * @ioprio: The I/O priority to set
1113 *
1114 * Detemine if the requested I/O priority change is permitted for the specified
1115 * task, returning 0 if permission is granted, -ve if denied.
1116 */
1117int cap_task_setioprio(struct task_struct *p, int ioprio)
1118{
1119	return cap_safe_nice(p);
1120}
1121
1122/**
1123 * cap_task_ioprio - Detemine if task priority change is permitted
1124 * @p: The task to affect
1125 * @nice: The nice value to set
1126 *
1127 * Detemine if the requested task priority change is permitted for the
1128 * specified task, returning 0 if permission is granted, -ve if denied.
1129 */
1130int cap_task_setnice(struct task_struct *p, int nice)
1131{
1132	return cap_safe_nice(p);
1133}
1134
1135/*
1136 * Implement PR_CAPBSET_DROP.  Attempt to remove the specified capability from
1137 * the current task's bounding set.  Returns 0 on success, -ve on error.
1138 */
1139static int cap_prctl_drop(unsigned long cap)
1140{
1141	struct cred *new;
1142
1143	if (!ns_capable(current_user_ns(), CAP_SETPCAP))
1144		return -EPERM;
1145	if (!cap_valid(cap))
1146		return -EINVAL;
1147
1148	new = prepare_creds();
1149	if (!new)
1150		return -ENOMEM;
1151	cap_lower(new->cap_bset, cap);
1152	return commit_creds(new);
1153}
1154
1155/**
1156 * cap_task_prctl - Implement process control functions for this security module
1157 * @option: The process control function requested
1158 * @arg2, @arg3, @arg4, @arg5: The argument data for this function
1159 *
1160 * Allow process control functions (sys_prctl()) to alter capabilities; may
1161 * also deny access to other functions not otherwise implemented here.
1162 *
1163 * Returns 0 or +ve on success, -ENOSYS if this function is not implemented
1164 * here, other -ve on error.  If -ENOSYS is returned, sys_prctl() and other LSM
1165 * modules will consider performing the function.
1166 */
1167int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3,
1168		   unsigned long arg4, unsigned long arg5)
1169{
1170	const struct cred *old = current_cred();
1171	struct cred *new;
 
 
 
 
 
1172
1173	switch (option) {
1174	case PR_CAPBSET_READ:
 
1175		if (!cap_valid(arg2))
1176			return -EINVAL;
1177		return !!cap_raised(old->cap_bset, arg2);
 
1178
1179	case PR_CAPBSET_DROP:
1180		return cap_prctl_drop(arg2);
 
 
 
1181
1182	/*
1183	 * The next four prctl's remain to assist with transitioning a
1184	 * system from legacy UID=0 based privilege (when filesystem
1185	 * capabilities are not in use) to a system using filesystem
1186	 * capabilities only - as the POSIX.1e draft intended.
1187	 *
1188	 * Note:
1189	 *
1190	 *  PR_SET_SECUREBITS =
1191	 *      issecure_mask(SECURE_KEEP_CAPS_LOCKED)
1192	 *    | issecure_mask(SECURE_NOROOT)
1193	 *    | issecure_mask(SECURE_NOROOT_LOCKED)
1194	 *    | issecure_mask(SECURE_NO_SETUID_FIXUP)
1195	 *    | issecure_mask(SECURE_NO_SETUID_FIXUP_LOCKED)
1196	 *
1197	 * will ensure that the current process and all of its
1198	 * children will be locked into a pure
1199	 * capability-based-privilege environment.
1200	 */
1201	case PR_SET_SECUREBITS:
1202		if ((((old->securebits & SECURE_ALL_LOCKS) >> 1)
1203		     & (old->securebits ^ arg2))			/*[1]*/
1204		    || ((old->securebits & SECURE_ALL_LOCKS & ~arg2))	/*[2]*/
 
1205		    || (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS))	/*[3]*/
1206		    || (cap_capable(current_cred(),
1207				    current_cred()->user_ns,
1208				    CAP_SETPCAP,
1209				    CAP_OPT_NONE) != 0)			/*[4]*/
1210			/*
1211			 * [1] no changing of bits that are locked
1212			 * [2] no unlocking of locks
1213			 * [3] no setting of unsupported bits
1214			 * [4] doing anything requires privilege (go read about
1215			 *     the "sendmail capabilities bug")
1216			 */
1217		    )
1218			/* cannot change a locked bit */
1219			return -EPERM;
1220
1221		new = prepare_creds();
1222		if (!new)
1223			return -ENOMEM;
1224		new->securebits = arg2;
1225		return commit_creds(new);
1226
1227	case PR_GET_SECUREBITS:
1228		return old->securebits;
 
1229
1230	case PR_GET_KEEPCAPS:
1231		return !!issecure(SECURE_KEEP_CAPS);
 
 
1232
1233	case PR_SET_KEEPCAPS:
 
1234		if (arg2 > 1) /* Note, we rely on arg2 being unsigned here */
1235			return -EINVAL;
 
1236		if (issecure(SECURE_KEEP_CAPS_LOCKED))
1237			return -EPERM;
1238
1239		new = prepare_creds();
1240		if (!new)
1241			return -ENOMEM;
1242		if (arg2)
1243			new->securebits |= issecure_mask(SECURE_KEEP_CAPS);
1244		else
1245			new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);
1246		return commit_creds(new);
1247
1248	case PR_CAP_AMBIENT:
1249		if (arg2 == PR_CAP_AMBIENT_CLEAR_ALL) {
1250			if (arg3 | arg4 | arg5)
1251				return -EINVAL;
1252
1253			new = prepare_creds();
1254			if (!new)
1255				return -ENOMEM;
1256			cap_clear(new->cap_ambient);
1257			return commit_creds(new);
1258		}
1259
1260		if (((!cap_valid(arg3)) | arg4 | arg5))
1261			return -EINVAL;
1262
1263		if (arg2 == PR_CAP_AMBIENT_IS_SET) {
1264			return !!cap_raised(current_cred()->cap_ambient, arg3);
1265		} else if (arg2 != PR_CAP_AMBIENT_RAISE &&
1266			   arg2 != PR_CAP_AMBIENT_LOWER) {
1267			return -EINVAL;
1268		} else {
1269			if (arg2 == PR_CAP_AMBIENT_RAISE &&
1270			    (!cap_raised(current_cred()->cap_permitted, arg3) ||
1271			     !cap_raised(current_cred()->cap_inheritable,
1272					 arg3) ||
1273			     issecure(SECURE_NO_CAP_AMBIENT_RAISE)))
1274				return -EPERM;
1275
1276			new = prepare_creds();
1277			if (!new)
1278				return -ENOMEM;
1279			if (arg2 == PR_CAP_AMBIENT_RAISE)
1280				cap_raise(new->cap_ambient, arg3);
1281			else
1282				cap_lower(new->cap_ambient, arg3);
1283			return commit_creds(new);
1284		}
1285
1286	default:
1287		/* No functionality available - continue with default */
1288		return -ENOSYS;
 
1289	}
 
 
 
 
 
 
 
 
 
1290}
1291
1292/**
1293 * cap_vm_enough_memory - Determine whether a new virtual mapping is permitted
1294 * @mm: The VM space in which the new mapping is to be made
1295 * @pages: The size of the mapping
1296 *
1297 * Determine whether the allocation of a new virtual mapping by the current
1298 * task is permitted, returning 1 if permission is granted, 0 if not.
1299 */
1300int cap_vm_enough_memory(struct mm_struct *mm, long pages)
1301{
1302	int cap_sys_admin = 0;
1303
1304	if (cap_capable(current_cred(), &init_user_ns,
1305				CAP_SYS_ADMIN, CAP_OPT_NOAUDIT) == 0)
1306		cap_sys_admin = 1;
1307
1308	return cap_sys_admin;
1309}
1310
1311/*
1312 * cap_mmap_addr - check if able to map given addr
1313 * @addr: address attempting to be mapped
1314 *
1315 * If the process is attempting to map memory below dac_mmap_min_addr they need
1316 * CAP_SYS_RAWIO.  The other parameters to this function are unused by the
1317 * capability security module.  Returns 0 if this mapping should be allowed
1318 * -EPERM if not.
1319 */
1320int cap_mmap_addr(unsigned long addr)
1321{
1322	int ret = 0;
1323
1324	if (addr < dac_mmap_min_addr) {
1325		ret = cap_capable(current_cred(), &init_user_ns, CAP_SYS_RAWIO,
1326				  CAP_OPT_NONE);
1327		/* set PF_SUPERPRIV if it turns out we allow the low mmap */
1328		if (ret == 0)
1329			current->flags |= PF_SUPERPRIV;
1330	}
1331	return ret;
1332}
1333
1334int cap_mmap_file(struct file *file, unsigned long reqprot,
1335		  unsigned long prot, unsigned long flags)
1336{
1337	return 0;
1338}
1339
1340#ifdef CONFIG_SECURITY
1341
1342static struct security_hook_list capability_hooks[] __lsm_ro_after_init = {
1343	LSM_HOOK_INIT(capable, cap_capable),
1344	LSM_HOOK_INIT(settime, cap_settime),
1345	LSM_HOOK_INIT(ptrace_access_check, cap_ptrace_access_check),
1346	LSM_HOOK_INIT(ptrace_traceme, cap_ptrace_traceme),
1347	LSM_HOOK_INIT(capget, cap_capget),
1348	LSM_HOOK_INIT(capset, cap_capset),
1349	LSM_HOOK_INIT(bprm_set_creds, cap_bprm_set_creds),
1350	LSM_HOOK_INIT(inode_need_killpriv, cap_inode_need_killpriv),
1351	LSM_HOOK_INIT(inode_killpriv, cap_inode_killpriv),
1352	LSM_HOOK_INIT(inode_getsecurity, cap_inode_getsecurity),
1353	LSM_HOOK_INIT(mmap_addr, cap_mmap_addr),
1354	LSM_HOOK_INIT(mmap_file, cap_mmap_file),
1355	LSM_HOOK_INIT(task_fix_setuid, cap_task_fix_setuid),
1356	LSM_HOOK_INIT(task_prctl, cap_task_prctl),
1357	LSM_HOOK_INIT(task_setscheduler, cap_task_setscheduler),
1358	LSM_HOOK_INIT(task_setioprio, cap_task_setioprio),
1359	LSM_HOOK_INIT(task_setnice, cap_task_setnice),
1360	LSM_HOOK_INIT(vm_enough_memory, cap_vm_enough_memory),
1361};
1362
1363static int __init capability_init(void)
1364{
1365	security_add_hooks(capability_hooks, ARRAY_SIZE(capability_hooks),
1366				"capability");
1367	return 0;
1368}
1369
1370DEFINE_LSM(capability) = {
1371	.name = "capability",
1372	.order = LSM_ORDER_FIRST,
1373	.init = capability_init,
1374};
1375
1376#endif /* CONFIG_SECURITY */