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