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, struct file *file,
 651			 bool *effective, bool *has_fcap)
 652{
 
 653	int rc = 0;
 654	struct cpu_vfs_cap_data vcaps;
 655
 656	cap_clear(bprm->cred->cap_permitted);
 657
 658	if (!file_caps_enabled)
 659		return 0;
 660
 661	if (!mnt_may_suid(file->f_path.mnt))
 662		return 0;
 663
 664	/*
 665	 * This check is redundant with mnt_may_suid() but is kept to make
 666	 * explicit that capability bits are limited to s_user_ns and its
 667	 * descendants.
 668	 */
 669	if (!current_in_userns(file->f_path.mnt->mnt_sb->s_user_ns))
 670		return 0;
 671
 672	rc = get_vfs_caps_from_disk(file->f_path.dentry, &vcaps);
 673	if (rc < 0) {
 674		if (rc == -EINVAL)
 675			printk(KERN_NOTICE "Invalid argument reading file caps for %s\n",
 676					bprm->filename);
 677		else if (rc == -ENODATA)
 678			rc = 0;
 679		goto out;
 680	}
 681
 682	rc = bprm_caps_from_vfs_caps(&vcaps, bprm, effective, has_fcap);
 
 
 
 683
 684out:
 
 685	if (rc)
 686		cap_clear(bprm->cred->cap_permitted);
 687
 688	return rc;
 689}
 690
 691static inline bool root_privileged(void) { return !issecure(SECURE_NOROOT); }
 692
 693static inline bool __is_real(kuid_t uid, struct cred *cred)
 694{ return uid_eq(cred->uid, uid); }
 695
 696static inline bool __is_eff(kuid_t uid, struct cred *cred)
 697{ return uid_eq(cred->euid, uid); }
 698
 699static inline bool __is_suid(kuid_t uid, struct cred *cred)
 700{ return !__is_real(uid, cred) && __is_eff(uid, cred); }
 701
 702/*
 703 * handle_privileged_root - Handle case of privileged root
 704 * @bprm: The execution parameters, including the proposed creds
 705 * @has_fcap: Are any file capabilities set?
 706 * @effective: Do we have effective root privilege?
 707 * @root_uid: This namespace' root UID WRT initial USER namespace
 708 *
 709 * Handle the case where root is privileged and hasn't been neutered by
 710 * SECURE_NOROOT.  If file capabilities are set, they won't be combined with
 711 * set UID root and nothing is changed.  If we are root, cap_permitted is
 712 * updated.  If we have become set UID root, the effective bit is set.
 713 */
 714static void handle_privileged_root(struct linux_binprm *bprm, bool has_fcap,
 715				   bool *effective, kuid_t root_uid)
 716{
 717	const struct cred *old = current_cred();
 718	struct cred *new = bprm->cred;
 719
 720	if (!root_privileged())
 721		return;
 722	/*
 723	 * If the legacy file capability is set, then don't set privs
 724	 * for a setuid root binary run by a non-root user.  Do set it
 725	 * for a root user just to cause least surprise to an admin.
 726	 */
 727	if (has_fcap && __is_suid(root_uid, new)) {
 728		warn_setuid_and_fcaps_mixed(bprm->filename);
 729		return;
 730	}
 731	/*
 732	 * To support inheritance of root-permissions and suid-root
 733	 * executables under compatibility mode, we override the
 734	 * capability sets for the file.
 735	 */
 736	if (__is_eff(root_uid, new) || __is_real(root_uid, new)) {
 737		/* pP' = (cap_bset & ~0) | (pI & ~0) */
 738		new->cap_permitted = cap_combine(old->cap_bset,
 739						 old->cap_inheritable);
 740	}
 741	/*
 742	 * If only the real uid is 0, we do not set the effective bit.
 743	 */
 744	if (__is_eff(root_uid, new))
 745		*effective = true;
 746}
 747
 748#define __cap_gained(field, target, source) \
 749	!cap_issubset(target->cap_##field, source->cap_##field)
 750#define __cap_grew(target, source, cred) \
 751	!cap_issubset(cred->cap_##target, cred->cap_##source)
 752#define __cap_full(field, cred) \
 753	cap_issubset(CAP_FULL_SET, cred->cap_##field)
 754
 755static inline bool __is_setuid(struct cred *new, const struct cred *old)
 756{ return !uid_eq(new->euid, old->uid); }
 757
 758static inline bool __is_setgid(struct cred *new, const struct cred *old)
 759{ return !gid_eq(new->egid, old->gid); }
 760
 761/*
 762 * 1) Audit candidate if current->cap_effective is set
 763 *
 764 * We do not bother to audit if 3 things are true:
 765 *   1) cap_effective has all caps
 766 *   2) we became root *OR* are were already root
 767 *   3) root is supposed to have all caps (SECURE_NOROOT)
 768 * Since this is just a normal root execing a process.
 769 *
 770 * Number 1 above might fail if you don't have a full bset, but I think
 771 * that is interesting information to audit.
 772 *
 773 * A number of other conditions require logging:
 774 * 2) something prevented setuid root getting all caps
 775 * 3) non-setuid root gets fcaps
 776 * 4) non-setuid root gets ambient
 777 */
 778static inline bool nonroot_raised_pE(struct cred *new, const struct cred *old,
 779				     kuid_t root, bool has_fcap)
 780{
 781	bool ret = false;
 782
 783	if ((__cap_grew(effective, ambient, new) &&
 784	     !(__cap_full(effective, new) &&
 785	       (__is_eff(root, new) || __is_real(root, new)) &&
 786	       root_privileged())) ||
 787	    (root_privileged() &&
 788	     __is_suid(root, new) &&
 789	     !__cap_full(effective, new)) ||
 790	    (!__is_setuid(new, old) &&
 791	     ((has_fcap &&
 792	       __cap_gained(permitted, new, old)) ||
 793	      __cap_gained(ambient, new, old))))
 794
 795		ret = true;
 796
 797	return ret;
 798}
 799
 800/**
 801 * cap_bprm_creds_from_file - Set up the proposed credentials for execve().
 802 * @bprm: The execution parameters, including the proposed creds
 803 * @file: The file to pull the credentials from
 804 *
 805 * Set up the proposed credentials for a new execution context being
 806 * constructed by execve().  The proposed creds in @bprm->cred is altered,
 807 * which won't take effect immediately.  Returns 0 if successful, -ve on error.
 808 */
 809int cap_bprm_creds_from_file(struct linux_binprm *bprm, struct file *file)
 810{
 811	/* Process setpcap binaries and capabilities for uid 0 */
 812	const struct cred *old = current_cred();
 813	struct cred *new = bprm->cred;
 814	bool effective = false, has_fcap = false, is_setid;
 815	int ret;
 816	kuid_t root_uid;
 817
 818	if (WARN_ON(!cap_ambient_invariant_ok(old)))
 819		return -EPERM;
 820
 821	ret = get_file_caps(bprm, file, &effective, &has_fcap);
 822	if (ret < 0)
 823		return ret;
 824
 825	root_uid = make_kuid(new->user_ns, 0);
 826
 827	handle_privileged_root(bprm, has_fcap, &effective, root_uid);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 828
 829	/* if we have fs caps, clear dangerous personality flags */
 830	if (__cap_gained(permitted, new, old))
 831		bprm->per_clear |= PER_CLEAR_ON_SETID;
 832
 
 833	/* Don't let someone trace a set[ug]id/setpcap binary with the revised
 834	 * credentials unless they have the appropriate permit.
 835	 *
 836	 * In addition, if NO_NEW_PRIVS, then ensure we get no new privs.
 837	 */
 838	is_setid = __is_setuid(new, old) || __is_setgid(new, old);
 839
 840	if ((is_setid || __cap_gained(permitted, new, old)) &&
 841	    ((bprm->unsafe & ~LSM_UNSAFE_PTRACE) ||
 842	     !ptracer_capable(current, new->user_ns))) {
 843		/* downgrade; they get no more than they had, and maybe less */
 844		if (!ns_capable(new->user_ns, CAP_SETUID) ||
 845		    (bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS)) {
 846			new->euid = new->uid;
 847			new->egid = new->gid;
 848		}
 849		new->cap_permitted = cap_intersect(new->cap_permitted,
 850						   old->cap_permitted);
 851	}
 852
 853	new->suid = new->fsuid = new->euid;
 854	new->sgid = new->fsgid = new->egid;
 855
 856	/* File caps or setid cancels ambient. */
 857	if (has_fcap || is_setid)
 858		cap_clear(new->cap_ambient);
 859
 860	/*
 861	 * Now that we've computed pA', update pP' to give:
 862	 *   pP' = (X & fP) | (pI & fI) | pA'
 863	 */
 864	new->cap_permitted = cap_combine(new->cap_permitted, new->cap_ambient);
 865
 866	/*
 867	 * Set pE' = (fE ? pP' : pA').  Because pA' is zero if fE is set,
 868	 * this is the same as pE' = (fE ? pP' : 0) | pA'.
 869	 */
 870	if (effective)
 871		new->cap_effective = new->cap_permitted;
 872	else
 873		new->cap_effective = new->cap_ambient;
 874
 875	if (WARN_ON(!cap_ambient_invariant_ok(new)))
 876		return -EPERM;
 877
 878	if (nonroot_raised_pE(new, old, root_uid, has_fcap)) {
 879		ret = audit_log_bprm_fcaps(bprm, new, old);
 880		if (ret < 0)
 881			return ret;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 882	}
 883
 884	new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);
 
 
 885
 886	if (WARN_ON(!cap_ambient_invariant_ok(new)))
 887		return -EPERM;
 
 
 
 
 
 
 
 
 
 
 
 
 888
 889	/* Check for privilege-elevated exec. */
 890	if (is_setid ||
 891	    (!__is_real(root_uid, new) &&
 892	     (effective ||
 893	      __cap_grew(permitted, ambient, new))))
 894		bprm->secureexec = 1;
 895
 896	return 0;
 
 897}
 898
 899/**
 900 * cap_inode_setxattr - Determine whether an xattr may be altered
 901 * @dentry: The inode/dentry being altered
 902 * @name: The name of the xattr to be changed
 903 * @value: The value that the xattr will be changed to
 904 * @size: The size of value
 905 * @flags: The replacement flag
 906 *
 907 * Determine whether an xattr may be altered or set on an inode, returning 0 if
 908 * permission is granted, -ve if denied.
 909 *
 910 * This is used to make sure security xattrs don't get updated or set by those
 911 * who aren't privileged to do so.
 912 */
 913int cap_inode_setxattr(struct dentry *dentry, const char *name,
 914		       const void *value, size_t size, int flags)
 915{
 916	struct user_namespace *user_ns = dentry->d_sb->s_user_ns;
 917
 918	/* Ignore non-security xattrs */
 919	if (strncmp(name, XATTR_SECURITY_PREFIX,
 920			XATTR_SECURITY_PREFIX_LEN) != 0)
 921		return 0;
 922
 923	/*
 924	 * For XATTR_NAME_CAPS the check will be done in
 925	 * cap_convert_nscap(), called by setxattr()
 926	 */
 927	if (strcmp(name, XATTR_NAME_CAPS) == 0)
 928		return 0;
 
 929
 930	if (!ns_capable(user_ns, CAP_SYS_ADMIN))
 
 
 931		return -EPERM;
 932	return 0;
 933}
 934
 935/**
 936 * cap_inode_removexattr - Determine whether an xattr may be removed
 937 * @dentry: The inode/dentry being altered
 938 * @name: The name of the xattr to be changed
 939 *
 940 * Determine whether an xattr may be removed from an inode, returning 0 if
 941 * permission is granted, -ve if denied.
 942 *
 943 * This is used to make sure security xattrs don't get removed by those who
 944 * aren't privileged to remove them.
 945 */
 946int cap_inode_removexattr(struct dentry *dentry, const char *name)
 947{
 948	struct user_namespace *user_ns = dentry->d_sb->s_user_ns;
 949
 950	/* Ignore non-security xattrs */
 951	if (strncmp(name, XATTR_SECURITY_PREFIX,
 952			XATTR_SECURITY_PREFIX_LEN) != 0)
 953		return 0;
 954
 955	if (strcmp(name, XATTR_NAME_CAPS) == 0) {
 956		/* security.capability gets namespaced */
 957		struct inode *inode = d_backing_inode(dentry);
 958		if (!inode)
 959			return -EINVAL;
 960		if (!capable_wrt_inode_uidgid(inode, CAP_SETFCAP))
 961			return -EPERM;
 962		return 0;
 963	}
 964
 965	if (!ns_capable(user_ns, CAP_SYS_ADMIN))
 
 
 966		return -EPERM;
 967	return 0;
 968}
 969
 970/*
 971 * cap_emulate_setxuid() fixes the effective / permitted capabilities of
 972 * a process after a call to setuid, setreuid, or setresuid.
 973 *
 974 *  1) When set*uiding _from_ one of {r,e,s}uid == 0 _to_ all of
 975 *  {r,e,s}uid != 0, the permitted and effective capabilities are
 976 *  cleared.
 977 *
 978 *  2) When set*uiding _from_ euid == 0 _to_ euid != 0, the effective
 979 *  capabilities of the process are cleared.
 980 *
 981 *  3) When set*uiding _from_ euid != 0 _to_ euid == 0, the effective
 982 *  capabilities are set to the permitted capabilities.
 983 *
 984 *  fsuid is handled elsewhere. fsuid == 0 and {r,e,s}uid!= 0 should
 985 *  never happen.
 986 *
 987 *  -astor
 988 *
 989 * cevans - New behaviour, Oct '99
 990 * A process may, via prctl(), elect to keep its capabilities when it
 991 * calls setuid() and switches away from uid==0. Both permitted and
 992 * effective sets will be retained.
 993 * Without this change, it was impossible for a daemon to drop only some
 994 * of its privilege. The call to setuid(!=0) would drop all privileges!
 995 * Keeping uid 0 is not an option because uid 0 owns too many vital
 996 * files..
 997 * Thanks to Olaf Kirch and Peter Benie for spotting this.
 998 */
 999static inline void cap_emulate_setxuid(struct cred *new, const struct cred *old)
1000{
1001	kuid_t root_uid = make_kuid(old->user_ns, 0);
1002
1003	if ((uid_eq(old->uid, root_uid) ||
1004	     uid_eq(old->euid, root_uid) ||
1005	     uid_eq(old->suid, root_uid)) &&
1006	    (!uid_eq(new->uid, root_uid) &&
1007	     !uid_eq(new->euid, root_uid) &&
1008	     !uid_eq(new->suid, root_uid))) {
1009		if (!issecure(SECURE_KEEP_CAPS)) {
1010			cap_clear(new->cap_permitted);
1011			cap_clear(new->cap_effective);
1012		}
1013
1014		/*
1015		 * Pre-ambient programs expect setresuid to nonroot followed
1016		 * by exec to drop capabilities.  We should make sure that
1017		 * this remains the case.
1018		 */
1019		cap_clear(new->cap_ambient);
1020	}
1021	if (uid_eq(old->euid, root_uid) && !uid_eq(new->euid, root_uid))
1022		cap_clear(new->cap_effective);
1023	if (!uid_eq(old->euid, root_uid) && uid_eq(new->euid, root_uid))
1024		new->cap_effective = new->cap_permitted;
1025}
1026
1027/**
1028 * cap_task_fix_setuid - Fix up the results of setuid() call
1029 * @new: The proposed credentials
1030 * @old: The current task's current credentials
1031 * @flags: Indications of what has changed
1032 *
1033 * Fix up the results of setuid() call before the credential changes are
1034 * actually applied, returning 0 to grant the changes, -ve to deny them.
1035 */
1036int cap_task_fix_setuid(struct cred *new, const struct cred *old, int flags)
1037{
1038	switch (flags) {
1039	case LSM_SETID_RE:
1040	case LSM_SETID_ID:
1041	case LSM_SETID_RES:
1042		/* juggle the capabilities to follow [RES]UID changes unless
1043		 * otherwise suppressed */
1044		if (!issecure(SECURE_NO_SETUID_FIXUP))
1045			cap_emulate_setxuid(new, old);
1046		break;
1047
1048	case LSM_SETID_FS:
1049		/* juggle the capabilties to follow FSUID changes, unless
1050		 * otherwise suppressed
1051		 *
1052		 * FIXME - is fsuser used for all CAP_FS_MASK capabilities?
1053		 *          if not, we might be a bit too harsh here.
1054		 */
1055		if (!issecure(SECURE_NO_SETUID_FIXUP)) {
1056			kuid_t root_uid = make_kuid(old->user_ns, 0);
1057			if (uid_eq(old->fsuid, root_uid) && !uid_eq(new->fsuid, root_uid))
1058				new->cap_effective =
1059					cap_drop_fs_set(new->cap_effective);
1060
1061			if (!uid_eq(old->fsuid, root_uid) && uid_eq(new->fsuid, root_uid))
1062				new->cap_effective =
1063					cap_raise_fs_set(new->cap_effective,
1064							 new->cap_permitted);
1065		}
1066		break;
1067
1068	default:
1069		return -EINVAL;
1070	}
1071
1072	return 0;
1073}
1074
1075/*
1076 * Rationale: code calling task_setscheduler, task_setioprio, and
1077 * task_setnice, assumes that
1078 *   . if capable(cap_sys_nice), then those actions should be allowed
1079 *   . if not capable(cap_sys_nice), but acting on your own processes,
1080 *   	then those actions should be allowed
1081 * This is insufficient now since you can call code without suid, but
1082 * yet with increased caps.
1083 * So we check for increased caps on the target process.
1084 */
1085static int cap_safe_nice(struct task_struct *p)
1086{
1087	int is_subset, ret = 0;
1088
1089	rcu_read_lock();
1090	is_subset = cap_issubset(__task_cred(p)->cap_permitted,
1091				 current_cred()->cap_permitted);
1092	if (!is_subset && !ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE))
1093		ret = -EPERM;
1094	rcu_read_unlock();
1095
1096	return ret;
 
 
1097}
1098
1099/**
1100 * cap_task_setscheduler - Detemine if scheduler policy change is permitted
1101 * @p: The task to affect
1102 *
1103 * Detemine if the requested scheduler policy change is permitted for the
1104 * specified task, returning 0 if permission is granted, -ve if denied.
1105 */
1106int cap_task_setscheduler(struct task_struct *p)
1107{
1108	return cap_safe_nice(p);
1109}
1110
1111/**
1112 * cap_task_ioprio - Detemine if I/O priority change is permitted
1113 * @p: The task to affect
1114 * @ioprio: The I/O priority to set
1115 *
1116 * Detemine if the requested I/O priority change is permitted for the specified
1117 * task, returning 0 if permission is granted, -ve if denied.
1118 */
1119int cap_task_setioprio(struct task_struct *p, int ioprio)
1120{
1121	return cap_safe_nice(p);
1122}
1123
1124/**
1125 * cap_task_ioprio - Detemine if task priority change is permitted
1126 * @p: The task to affect
1127 * @nice: The nice value to set
1128 *
1129 * Detemine if the requested task priority change is permitted for the
1130 * specified task, returning 0 if permission is granted, -ve if denied.
1131 */
1132int cap_task_setnice(struct task_struct *p, int nice)
1133{
1134	return cap_safe_nice(p);
1135}
1136
1137/*
1138 * Implement PR_CAPBSET_DROP.  Attempt to remove the specified capability from
1139 * the current task's bounding set.  Returns 0 on success, -ve on error.
1140 */
1141static int cap_prctl_drop(unsigned long cap)
1142{
1143	struct cred *new;
1144
1145	if (!ns_capable(current_user_ns(), CAP_SETPCAP))
1146		return -EPERM;
1147	if (!cap_valid(cap))
1148		return -EINVAL;
1149
1150	new = prepare_creds();
1151	if (!new)
1152		return -ENOMEM;
1153	cap_lower(new->cap_bset, cap);
1154	return commit_creds(new);
1155}
1156
1157/**
1158 * cap_task_prctl - Implement process control functions for this security module
1159 * @option: The process control function requested
1160 * @arg2, @arg3, @arg4, @arg5: The argument data for this function
1161 *
1162 * Allow process control functions (sys_prctl()) to alter capabilities; may
1163 * also deny access to other functions not otherwise implemented here.
1164 *
1165 * Returns 0 or +ve on success, -ENOSYS if this function is not implemented
1166 * here, other -ve on error.  If -ENOSYS is returned, sys_prctl() and other LSM
1167 * modules will consider performing the function.
1168 */
1169int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3,
1170		   unsigned long arg4, unsigned long arg5)
1171{
1172	const struct cred *old = current_cred();
1173	struct cred *new;
 
 
 
 
 
1174
1175	switch (option) {
1176	case PR_CAPBSET_READ:
 
1177		if (!cap_valid(arg2))
1178			return -EINVAL;
1179		return !!cap_raised(old->cap_bset, arg2);
 
1180
1181	case PR_CAPBSET_DROP:
1182		return cap_prctl_drop(arg2);
 
 
 
1183
1184	/*
1185	 * The next four prctl's remain to assist with transitioning a
1186	 * system from legacy UID=0 based privilege (when filesystem
1187	 * capabilities are not in use) to a system using filesystem
1188	 * capabilities only - as the POSIX.1e draft intended.
1189	 *
1190	 * Note:
1191	 *
1192	 *  PR_SET_SECUREBITS =
1193	 *      issecure_mask(SECURE_KEEP_CAPS_LOCKED)
1194	 *    | issecure_mask(SECURE_NOROOT)
1195	 *    | issecure_mask(SECURE_NOROOT_LOCKED)
1196	 *    | issecure_mask(SECURE_NO_SETUID_FIXUP)
1197	 *    | issecure_mask(SECURE_NO_SETUID_FIXUP_LOCKED)
1198	 *
1199	 * will ensure that the current process and all of its
1200	 * children will be locked into a pure
1201	 * capability-based-privilege environment.
1202	 */
1203	case PR_SET_SECUREBITS:
1204		if ((((old->securebits & SECURE_ALL_LOCKS) >> 1)
1205		     & (old->securebits ^ arg2))			/*[1]*/
1206		    || ((old->securebits & SECURE_ALL_LOCKS & ~arg2))	/*[2]*/
 
1207		    || (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS))	/*[3]*/
1208		    || (cap_capable(current_cred(),
1209				    current_cred()->user_ns,
1210				    CAP_SETPCAP,
1211				    CAP_OPT_NONE) != 0)			/*[4]*/
1212			/*
1213			 * [1] no changing of bits that are locked
1214			 * [2] no unlocking of locks
1215			 * [3] no setting of unsupported bits
1216			 * [4] doing anything requires privilege (go read about
1217			 *     the "sendmail capabilities bug")
1218			 */
1219		    )
1220			/* cannot change a locked bit */
1221			return -EPERM;
1222
1223		new = prepare_creds();
1224		if (!new)
1225			return -ENOMEM;
1226		new->securebits = arg2;
1227		return commit_creds(new);
1228
1229	case PR_GET_SECUREBITS:
1230		return old->securebits;
 
1231
1232	case PR_GET_KEEPCAPS:
1233		return !!issecure(SECURE_KEEP_CAPS);
 
 
1234
1235	case PR_SET_KEEPCAPS:
 
1236		if (arg2 > 1) /* Note, we rely on arg2 being unsigned here */
1237			return -EINVAL;
 
1238		if (issecure(SECURE_KEEP_CAPS_LOCKED))
1239			return -EPERM;
1240
1241		new = prepare_creds();
1242		if (!new)
1243			return -ENOMEM;
1244		if (arg2)
1245			new->securebits |= issecure_mask(SECURE_KEEP_CAPS);
1246		else
1247			new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);
1248		return commit_creds(new);
1249
1250	case PR_CAP_AMBIENT:
1251		if (arg2 == PR_CAP_AMBIENT_CLEAR_ALL) {
1252			if (arg3 | arg4 | arg5)
1253				return -EINVAL;
1254
1255			new = prepare_creds();
1256			if (!new)
1257				return -ENOMEM;
1258			cap_clear(new->cap_ambient);
1259			return commit_creds(new);
1260		}
1261
1262		if (((!cap_valid(arg3)) | arg4 | arg5))
1263			return -EINVAL;
1264
1265		if (arg2 == PR_CAP_AMBIENT_IS_SET) {
1266			return !!cap_raised(current_cred()->cap_ambient, arg3);
1267		} else if (arg2 != PR_CAP_AMBIENT_RAISE &&
1268			   arg2 != PR_CAP_AMBIENT_LOWER) {
1269			return -EINVAL;
1270		} else {
1271			if (arg2 == PR_CAP_AMBIENT_RAISE &&
1272			    (!cap_raised(current_cred()->cap_permitted, arg3) ||
1273			     !cap_raised(current_cred()->cap_inheritable,
1274					 arg3) ||
1275			     issecure(SECURE_NO_CAP_AMBIENT_RAISE)))
1276				return -EPERM;
1277
1278			new = prepare_creds();
1279			if (!new)
1280				return -ENOMEM;
1281			if (arg2 == PR_CAP_AMBIENT_RAISE)
1282				cap_raise(new->cap_ambient, arg3);
1283			else
1284				cap_lower(new->cap_ambient, arg3);
1285			return commit_creds(new);
1286		}
1287
1288	default:
1289		/* No functionality available - continue with default */
1290		return -ENOSYS;
 
1291	}
 
 
 
 
 
 
 
 
 
1292}
1293
1294/**
1295 * cap_vm_enough_memory - Determine whether a new virtual mapping is permitted
1296 * @mm: The VM space in which the new mapping is to be made
1297 * @pages: The size of the mapping
1298 *
1299 * Determine whether the allocation of a new virtual mapping by the current
1300 * task is permitted, returning 1 if permission is granted, 0 if not.
1301 */
1302int cap_vm_enough_memory(struct mm_struct *mm, long pages)
1303{
1304	int cap_sys_admin = 0;
1305
1306	if (cap_capable(current_cred(), &init_user_ns,
1307				CAP_SYS_ADMIN, CAP_OPT_NOAUDIT) == 0)
1308		cap_sys_admin = 1;
1309
1310	return cap_sys_admin;
1311}
1312
1313/*
1314 * cap_mmap_addr - check if able to map given addr
1315 * @addr: address attempting to be mapped
1316 *
1317 * If the process is attempting to map memory below dac_mmap_min_addr they need
1318 * CAP_SYS_RAWIO.  The other parameters to this function are unused by the
1319 * capability security module.  Returns 0 if this mapping should be allowed
1320 * -EPERM if not.
1321 */
1322int cap_mmap_addr(unsigned long addr)
1323{
1324	int ret = 0;
1325
1326	if (addr < dac_mmap_min_addr) {
1327		ret = cap_capable(current_cred(), &init_user_ns, CAP_SYS_RAWIO,
1328				  CAP_OPT_NONE);
1329		/* set PF_SUPERPRIV if it turns out we allow the low mmap */
1330		if (ret == 0)
1331			current->flags |= PF_SUPERPRIV;
1332	}
1333	return ret;
1334}
1335
1336int cap_mmap_file(struct file *file, unsigned long reqprot,
1337		  unsigned long prot, unsigned long flags)
1338{
1339	return 0;
1340}
1341
1342#ifdef CONFIG_SECURITY
1343
1344static struct security_hook_list capability_hooks[] __lsm_ro_after_init = {
1345	LSM_HOOK_INIT(capable, cap_capable),
1346	LSM_HOOK_INIT(settime, cap_settime),
1347	LSM_HOOK_INIT(ptrace_access_check, cap_ptrace_access_check),
1348	LSM_HOOK_INIT(ptrace_traceme, cap_ptrace_traceme),
1349	LSM_HOOK_INIT(capget, cap_capget),
1350	LSM_HOOK_INIT(capset, cap_capset),
1351	LSM_HOOK_INIT(bprm_creds_from_file, cap_bprm_creds_from_file),
1352	LSM_HOOK_INIT(inode_need_killpriv, cap_inode_need_killpriv),
1353	LSM_HOOK_INIT(inode_killpriv, cap_inode_killpriv),
1354	LSM_HOOK_INIT(inode_getsecurity, cap_inode_getsecurity),
1355	LSM_HOOK_INIT(mmap_addr, cap_mmap_addr),
1356	LSM_HOOK_INIT(mmap_file, cap_mmap_file),
1357	LSM_HOOK_INIT(task_fix_setuid, cap_task_fix_setuid),
1358	LSM_HOOK_INIT(task_prctl, cap_task_prctl),
1359	LSM_HOOK_INIT(task_setscheduler, cap_task_setscheduler),
1360	LSM_HOOK_INIT(task_setioprio, cap_task_setioprio),
1361	LSM_HOOK_INIT(task_setnice, cap_task_setnice),
1362	LSM_HOOK_INIT(vm_enough_memory, cap_vm_enough_memory),
1363};
1364
1365static int __init capability_init(void)
1366{
1367	security_add_hooks(capability_hooks, ARRAY_SIZE(capability_hooks),
1368				"capability");
1369	return 0;
1370}
1371
1372DEFINE_LSM(capability) = {
1373	.name = "capability",
1374	.order = LSM_ORDER_FIRST,
1375	.init = capability_init,
1376};
1377
1378#endif /* CONFIG_SECURITY */