1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* Common capabilities, needed by capability.o. 3 */ 4 5 #include <linux/capability.h> 6 #include <linux/audit.h> 7 #include <linux/init.h> 8 #include <linux/kernel.h> 9 #include <linux/lsm_hooks.h> 10 #include <linux/file.h> 11 #include <linux/mm.h> 12 #include <linux/mman.h> 13 #include <linux/pagemap.h> 14 #include <linux/swap.h> 15 #include <linux/skbuff.h> 16 #include <linux/netlink.h> 17 #include <linux/ptrace.h> 18 #include <linux/xattr.h> 19 #include <linux/hugetlb.h> 20 #include <linux/mount.h> 21 #include <linux/sched.h> 22 #include <linux/prctl.h> 23 #include <linux/securebits.h> 24 #include <linux/user_namespace.h> 25 #include <linux/binfmts.h> 26 #include <linux/personality.h> 27 28 /* 29 * If a non-root user executes a setuid-root binary in 30 * !secure(SECURE_NOROOT) mode, then we raise capabilities. 31 * However if fE is also set, then the intent is for only 32 * the file capabilities to be applied, and the setuid-root 33 * bit is left on either to change the uid (plausible) or 34 * to get full privilege on a kernel without file capabilities 35 * support. So in that case we do not raise capabilities. 36 * 37 * Warn if that happens, once per boot. 38 */ 39 static void warn_setuid_and_fcaps_mixed(const char *fname) 40 { 41 static int warned; 42 if (!warned) { 43 printk(KERN_INFO "warning: `%s' has both setuid-root and" 44 " effective capabilities. Therefore not raising all" 45 " capabilities.\n", fname); 46 warned = 1; 47 } 48 } 49 50 /** 51 * cap_capable - Determine whether a task has a particular effective capability 52 * @cred: The credentials to use 53 * @ns: The user namespace in which we need the capability 54 * @cap: The capability to check for 55 * @opts: Bitmask of options defined in include/linux/security.h 56 * 57 * Determine whether the nominated task has the specified capability amongst 58 * its effective set, returning 0 if it does, -ve if it does not. 59 * 60 * NOTE WELL: cap_has_capability() cannot be used like the kernel's capable() 61 * and has_capability() functions. That is, it has the reverse semantics: 62 * cap_has_capability() returns 0 when a task has a capability, but the 63 * kernel's capable() and has_capability() returns 1 for this case. 64 */ 65 int cap_capable(const struct cred *cred, struct user_namespace *targ_ns, 66 int cap, unsigned int opts) 67 { 68 struct user_namespace *ns = targ_ns; 69 70 /* See if cred has the capability in the target user namespace 71 * by examining the target user namespace and all of the target 72 * user namespace's parents. 73 */ 74 for (;;) { 75 /* Do we have the necessary capabilities? */ 76 if (ns == cred->user_ns) 77 return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM; 78 79 /* 80 * If we're already at a lower level than we're looking for, 81 * we're done searching. 82 */ 83 if (ns->level <= cred->user_ns->level) 84 return -EPERM; 85 86 /* 87 * The owner of the user namespace in the parent of the 88 * user namespace has all caps. 89 */ 90 if ((ns->parent == cred->user_ns) && uid_eq(ns->owner, cred->euid)) 91 return 0; 92 93 /* 94 * If you have a capability in a parent user ns, then you have 95 * it over all children user namespaces as well. 96 */ 97 ns = ns->parent; 98 } 99 100 /* We never get here */ 101 } 102 103 /** 104 * cap_settime - Determine whether the current process may set the system clock 105 * @ts: The time to set 106 * @tz: The timezone to set 107 * 108 * Determine whether the current process may set the system clock and timezone 109 * information, returning 0 if permission granted, -ve if denied. 110 */ 111 int cap_settime(const struct timespec64 *ts, const struct timezone *tz) 112 { 113 if (!capable(CAP_SYS_TIME)) 114 return -EPERM; 115 return 0; 116 } 117 118 /** 119 * cap_ptrace_access_check - Determine whether the current process may access 120 * another 121 * @child: The process to be accessed 122 * @mode: The mode of attachment. 123 * 124 * If we are in the same or an ancestor user_ns and have all the target 125 * task's capabilities, then ptrace access is allowed. 126 * If we have the ptrace capability to the target user_ns, then ptrace 127 * access is allowed. 128 * Else denied. 129 * 130 * Determine whether a process may access another, returning 0 if permission 131 * granted, -ve if denied. 132 */ 133 int cap_ptrace_access_check(struct task_struct *child, unsigned int mode) 134 { 135 int ret = 0; 136 const struct cred *cred, *child_cred; 137 const kernel_cap_t *caller_caps; 138 139 rcu_read_lock(); 140 cred = current_cred(); 141 child_cred = __task_cred(child); 142 if (mode & PTRACE_MODE_FSCREDS) 143 caller_caps = &cred->cap_effective; 144 else 145 caller_caps = &cred->cap_permitted; 146 if (cred->user_ns == child_cred->user_ns && 147 cap_issubset(child_cred->cap_permitted, *caller_caps)) 148 goto out; 149 if (ns_capable(child_cred->user_ns, CAP_SYS_PTRACE)) 150 goto out; 151 ret = -EPERM; 152 out: 153 rcu_read_unlock(); 154 return ret; 155 } 156 157 /** 158 * cap_ptrace_traceme - Determine whether another process may trace the current 159 * @parent: The task proposed to be the tracer 160 * 161 * If parent is in the same or an ancestor user_ns and has all current's 162 * capabilities, then ptrace access is allowed. 163 * If parent has the ptrace capability to current's user_ns, then ptrace 164 * access is allowed. 165 * Else denied. 166 * 167 * Determine whether the nominated task is permitted to trace the current 168 * process, returning 0 if permission is granted, -ve if denied. 169 */ 170 int cap_ptrace_traceme(struct task_struct *parent) 171 { 172 int ret = 0; 173 const struct cred *cred, *child_cred; 174 175 rcu_read_lock(); 176 cred = __task_cred(parent); 177 child_cred = current_cred(); 178 if (cred->user_ns == child_cred->user_ns && 179 cap_issubset(child_cred->cap_permitted, cred->cap_permitted)) 180 goto out; 181 if (has_ns_capability(parent, child_cred->user_ns, CAP_SYS_PTRACE)) 182 goto out; 183 ret = -EPERM; 184 out: 185 rcu_read_unlock(); 186 return ret; 187 } 188 189 /** 190 * cap_capget - Retrieve a task's capability sets 191 * @target: The task from which to retrieve the capability sets 192 * @effective: The place to record the effective set 193 * @inheritable: The place to record the inheritable set 194 * @permitted: The place to record the permitted set 195 * 196 * This function retrieves the capabilities of the nominated task and returns 197 * them to the caller. 198 */ 199 int cap_capget(struct task_struct *target, kernel_cap_t *effective, 200 kernel_cap_t *inheritable, kernel_cap_t *permitted) 201 { 202 const struct cred *cred; 203 204 /* Derived from kernel/capability.c:sys_capget. */ 205 rcu_read_lock(); 206 cred = __task_cred(target); 207 *effective = cred->cap_effective; 208 *inheritable = cred->cap_inheritable; 209 *permitted = cred->cap_permitted; 210 rcu_read_unlock(); 211 return 0; 212 } 213 214 /* 215 * Determine whether the inheritable capabilities are limited to the old 216 * permitted set. Returns 1 if they are limited, 0 if they are not. 217 */ 218 static inline int cap_inh_is_capped(void) 219 { 220 /* they are so limited unless the current task has the CAP_SETPCAP 221 * capability 222 */ 223 if (cap_capable(current_cred(), current_cred()->user_ns, 224 CAP_SETPCAP, CAP_OPT_NONE) == 0) 225 return 0; 226 return 1; 227 } 228 229 /** 230 * cap_capset - Validate and apply proposed changes to current's capabilities 231 * @new: The proposed new credentials; alterations should be made here 232 * @old: The current task's current credentials 233 * @effective: A pointer to the proposed new effective capabilities set 234 * @inheritable: A pointer to the proposed new inheritable capabilities set 235 * @permitted: A pointer to the proposed new permitted capabilities set 236 * 237 * This function validates and applies a proposed mass change to the current 238 * process's capability sets. The changes are made to the proposed new 239 * credentials, and assuming no error, will be committed by the caller of LSM. 240 */ 241 int cap_capset(struct cred *new, 242 const struct cred *old, 243 const kernel_cap_t *effective, 244 const kernel_cap_t *inheritable, 245 const kernel_cap_t *permitted) 246 { 247 if (cap_inh_is_capped() && 248 !cap_issubset(*inheritable, 249 cap_combine(old->cap_inheritable, 250 old->cap_permitted))) 251 /* incapable of using this inheritable set */ 252 return -EPERM; 253 254 if (!cap_issubset(*inheritable, 255 cap_combine(old->cap_inheritable, 256 old->cap_bset))) 257 /* no new pI capabilities outside bounding set */ 258 return -EPERM; 259 260 /* verify restrictions on target's new Permitted set */ 261 if (!cap_issubset(*permitted, old->cap_permitted)) 262 return -EPERM; 263 264 /* verify the _new_Effective_ is a subset of the _new_Permitted_ */ 265 if (!cap_issubset(*effective, *permitted)) 266 return -EPERM; 267 268 new->cap_effective = *effective; 269 new->cap_inheritable = *inheritable; 270 new->cap_permitted = *permitted; 271 272 /* 273 * Mask off ambient bits that are no longer both permitted and 274 * inheritable. 275 */ 276 new->cap_ambient = cap_intersect(new->cap_ambient, 277 cap_intersect(*permitted, 278 *inheritable)); 279 if (WARN_ON(!cap_ambient_invariant_ok(new))) 280 return -EINVAL; 281 return 0; 282 } 283 284 /** 285 * cap_inode_need_killpriv - Determine if inode change affects privileges 286 * @dentry: The inode/dentry in being changed with change marked ATTR_KILL_PRIV 287 * 288 * Determine if an inode having a change applied that's marked ATTR_KILL_PRIV 289 * affects the security markings on that inode, and if it is, should 290 * inode_killpriv() be invoked or the change rejected. 291 * 292 * Returns 1 if security.capability has a value, meaning inode_killpriv() 293 * is required, 0 otherwise, meaning inode_killpriv() is not required. 294 */ 295 int cap_inode_need_killpriv(struct dentry *dentry) 296 { 297 struct inode *inode = d_backing_inode(dentry); 298 int error; 299 300 error = __vfs_getxattr(dentry, inode, XATTR_NAME_CAPS, NULL, 0); 301 return error > 0; 302 } 303 304 /** 305 * cap_inode_killpriv - Erase the security markings on an inode 306 * 307 * @mnt_userns: user namespace of the mount the inode was found from 308 * @dentry: The inode/dentry to alter 309 * 310 * Erase the privilege-enhancing security markings on an inode. 311 * 312 * If the inode has been found through an idmapped mount the user namespace of 313 * the vfsmount must be passed through @mnt_userns. This function will then 314 * take care to map the inode according to @mnt_userns before checking 315 * permissions. On non-idmapped mounts or if permission checking is to be 316 * performed on the raw inode simply passs init_user_ns. 317 * 318 * Returns 0 if successful, -ve on error. 319 */ 320 int cap_inode_killpriv(struct user_namespace *mnt_userns, struct dentry *dentry) 321 { 322 int error; 323 324 error = __vfs_removexattr(mnt_userns, dentry, XATTR_NAME_CAPS); 325 if (error == -EOPNOTSUPP) 326 error = 0; 327 return error; 328 } 329 330 static bool rootid_owns_currentns(kuid_t kroot) 331 { 332 struct user_namespace *ns; 333 334 if (!uid_valid(kroot)) 335 return false; 336 337 for (ns = current_user_ns(); ; ns = ns->parent) { 338 if (from_kuid(ns, kroot) == 0) 339 return true; 340 if (ns == &init_user_ns) 341 break; 342 } 343 344 return false; 345 } 346 347 static __u32 sansflags(__u32 m) 348 { 349 return m & ~VFS_CAP_FLAGS_EFFECTIVE; 350 } 351 352 static bool is_v2header(size_t size, const struct vfs_cap_data *cap) 353 { 354 if (size != XATTR_CAPS_SZ_2) 355 return false; 356 return sansflags(le32_to_cpu(cap->magic_etc)) == VFS_CAP_REVISION_2; 357 } 358 359 static bool is_v3header(size_t size, const struct vfs_cap_data *cap) 360 { 361 if (size != XATTR_CAPS_SZ_3) 362 return false; 363 return sansflags(le32_to_cpu(cap->magic_etc)) == VFS_CAP_REVISION_3; 364 } 365 366 /* 367 * getsecurity: We are called for security.* before any attempt to read the 368 * xattr from the inode itself. 369 * 370 * This gives us a chance to read the on-disk value and convert it. If we 371 * return -EOPNOTSUPP, then vfs_getxattr() will call the i_op handler. 372 * 373 * Note we are not called by vfs_getxattr_alloc(), but that is only called 374 * by the integrity subsystem, which really wants the unconverted values - 375 * so that's good. 376 */ 377 int cap_inode_getsecurity(struct user_namespace *mnt_userns, 378 struct inode *inode, const char *name, void **buffer, 379 bool alloc) 380 { 381 int size, ret; 382 kuid_t kroot; 383 uid_t root, mappedroot; 384 char *tmpbuf = NULL; 385 struct vfs_cap_data *cap; 386 struct vfs_ns_cap_data *nscap; 387 struct dentry *dentry; 388 struct user_namespace *fs_ns; 389 390 if (strcmp(name, "capability") != 0) 391 return -EOPNOTSUPP; 392 393 dentry = d_find_any_alias(inode); 394 if (!dentry) 395 return -EINVAL; 396 397 size = sizeof(struct vfs_ns_cap_data); 398 ret = (int)vfs_getxattr_alloc(mnt_userns, dentry, XATTR_NAME_CAPS, 399 &tmpbuf, size, GFP_NOFS); 400 dput(dentry); 401 402 if (ret < 0) 403 return ret; 404 405 fs_ns = inode->i_sb->s_user_ns; 406 cap = (struct vfs_cap_data *) tmpbuf; 407 if (is_v2header((size_t) ret, cap)) { 408 /* If this is sizeof(vfs_cap_data) then we're ok with the 409 * on-disk value, so return that. */ 410 if (alloc) 411 *buffer = tmpbuf; 412 else 413 kfree(tmpbuf); 414 return ret; 415 } else if (!is_v3header((size_t) ret, cap)) { 416 kfree(tmpbuf); 417 return -EINVAL; 418 } 419 420 nscap = (struct vfs_ns_cap_data *) tmpbuf; 421 root = le32_to_cpu(nscap->rootid); 422 kroot = make_kuid(fs_ns, root); 423 424 /* If this is an idmapped mount shift the kuid. */ 425 kroot = kuid_into_mnt(mnt_userns, kroot); 426 427 /* If the root kuid maps to a valid uid in current ns, then return 428 * this as a nscap. */ 429 mappedroot = from_kuid(current_user_ns(), kroot); 430 if (mappedroot != (uid_t)-1 && mappedroot != (uid_t)0) { 431 if (alloc) { 432 *buffer = tmpbuf; 433 nscap->rootid = cpu_to_le32(mappedroot); 434 } else 435 kfree(tmpbuf); 436 return size; 437 } 438 439 if (!rootid_owns_currentns(kroot)) { 440 kfree(tmpbuf); 441 return -EOPNOTSUPP; 442 } 443 444 /* This comes from a parent namespace. Return as a v2 capability */ 445 size = sizeof(struct vfs_cap_data); 446 if (alloc) { 447 *buffer = kmalloc(size, GFP_ATOMIC); 448 if (*buffer) { 449 struct vfs_cap_data *cap = *buffer; 450 __le32 nsmagic, magic; 451 magic = VFS_CAP_REVISION_2; 452 nsmagic = le32_to_cpu(nscap->magic_etc); 453 if (nsmagic & VFS_CAP_FLAGS_EFFECTIVE) 454 magic |= VFS_CAP_FLAGS_EFFECTIVE; 455 memcpy(&cap->data, &nscap->data, sizeof(__le32) * 2 * VFS_CAP_U32); 456 cap->magic_etc = cpu_to_le32(magic); 457 } else { 458 size = -ENOMEM; 459 } 460 } 461 kfree(tmpbuf); 462 return size; 463 } 464 465 /** 466 * rootid_from_xattr - translate root uid of vfs caps 467 * 468 * @value: vfs caps value which may be modified by this function 469 * @size: size of @ivalue 470 * @task_ns: user namespace of the caller 471 * @mnt_userns: user namespace of the mount the inode was found from 472 * 473 * If the inode has been found through an idmapped mount the user namespace of 474 * the vfsmount must be passed through @mnt_userns. This function will then 475 * take care to map the inode according to @mnt_userns before checking 476 * permissions. On non-idmapped mounts or if permission checking is to be 477 * performed on the raw inode simply passs init_user_ns. 478 */ 479 static kuid_t rootid_from_xattr(const void *value, size_t size, 480 struct user_namespace *task_ns, 481 struct user_namespace *mnt_userns) 482 { 483 const struct vfs_ns_cap_data *nscap = value; 484 kuid_t rootkid; 485 uid_t rootid = 0; 486 487 if (size == XATTR_CAPS_SZ_3) 488 rootid = le32_to_cpu(nscap->rootid); 489 490 rootkid = make_kuid(task_ns, rootid); 491 return kuid_from_mnt(mnt_userns, rootkid); 492 } 493 494 static bool validheader(size_t size, const struct vfs_cap_data *cap) 495 { 496 return is_v2header(size, cap) || is_v3header(size, cap); 497 } 498 499 /** 500 * cap_convert_nscap - check vfs caps 501 * 502 * @mnt_userns: user namespace of the mount the inode was found from 503 * @dentry: used to retrieve inode to check permissions on 504 * @ivalue: vfs caps value which may be modified by this function 505 * @size: size of @ivalue 506 * 507 * User requested a write of security.capability. If needed, update the 508 * xattr to change from v2 to v3, or to fixup the v3 rootid. 509 * 510 * If the inode has been found through an idmapped mount the user namespace of 511 * the vfsmount must be passed through @mnt_userns. This function will then 512 * take care to map the inode according to @mnt_userns before checking 513 * permissions. On non-idmapped mounts or if permission checking is to be 514 * performed on the raw inode simply passs init_user_ns. 515 * 516 * If all is ok, we return the new size, on error return < 0. 517 */ 518 int cap_convert_nscap(struct user_namespace *mnt_userns, struct dentry *dentry, 519 const void **ivalue, size_t size) 520 { 521 struct vfs_ns_cap_data *nscap; 522 uid_t nsrootid; 523 const struct vfs_cap_data *cap = *ivalue; 524 __u32 magic, nsmagic; 525 struct inode *inode = d_backing_inode(dentry); 526 struct user_namespace *task_ns = current_user_ns(), 527 *fs_ns = inode->i_sb->s_user_ns; 528 kuid_t rootid; 529 size_t newsize; 530 531 if (!*ivalue) 532 return -EINVAL; 533 if (!validheader(size, cap)) 534 return -EINVAL; 535 if (!capable_wrt_inode_uidgid(mnt_userns, inode, CAP_SETFCAP)) 536 return -EPERM; 537 if (size == XATTR_CAPS_SZ_2 && (mnt_userns == &init_user_ns)) 538 if (ns_capable(inode->i_sb->s_user_ns, CAP_SETFCAP)) 539 /* user is privileged, just write the v2 */ 540 return size; 541 542 rootid = rootid_from_xattr(*ivalue, size, task_ns, mnt_userns); 543 if (!uid_valid(rootid)) 544 return -EINVAL; 545 546 nsrootid = from_kuid(fs_ns, rootid); 547 if (nsrootid == -1) 548 return -EINVAL; 549 550 newsize = sizeof(struct vfs_ns_cap_data); 551 nscap = kmalloc(newsize, GFP_ATOMIC); 552 if (!nscap) 553 return -ENOMEM; 554 nscap->rootid = cpu_to_le32(nsrootid); 555 nsmagic = VFS_CAP_REVISION_3; 556 magic = le32_to_cpu(cap->magic_etc); 557 if (magic & VFS_CAP_FLAGS_EFFECTIVE) 558 nsmagic |= VFS_CAP_FLAGS_EFFECTIVE; 559 nscap->magic_etc = cpu_to_le32(nsmagic); 560 memcpy(&nscap->data, &cap->data, sizeof(__le32) * 2 * VFS_CAP_U32); 561 562 *ivalue = nscap; 563 return newsize; 564 } 565 566 /* 567 * Calculate the new process capability sets from the capability sets attached 568 * to a file. 569 */ 570 static inline int bprm_caps_from_vfs_caps(struct cpu_vfs_cap_data *caps, 571 struct linux_binprm *bprm, 572 bool *effective, 573 bool *has_fcap) 574 { 575 struct cred *new = bprm->cred; 576 unsigned i; 577 int ret = 0; 578 579 if (caps->magic_etc & VFS_CAP_FLAGS_EFFECTIVE) 580 *effective = true; 581 582 if (caps->magic_etc & VFS_CAP_REVISION_MASK) 583 *has_fcap = true; 584 585 CAP_FOR_EACH_U32(i) { 586 __u32 permitted = caps->permitted.cap[i]; 587 __u32 inheritable = caps->inheritable.cap[i]; 588 589 /* 590 * pP' = (X & fP) | (pI & fI) 591 * The addition of pA' is handled later. 592 */ 593 new->cap_permitted.cap[i] = 594 (new->cap_bset.cap[i] & permitted) | 595 (new->cap_inheritable.cap[i] & inheritable); 596 597 if (permitted & ~new->cap_permitted.cap[i]) 598 /* insufficient to execute correctly */ 599 ret = -EPERM; 600 } 601 602 /* 603 * For legacy apps, with no internal support for recognizing they 604 * do not have enough capabilities, we return an error if they are 605 * missing some "forced" (aka file-permitted) capabilities. 606 */ 607 return *effective ? ret : 0; 608 } 609 610 /** 611 * get_vfs_caps_from_disk - retrieve vfs caps from disk 612 * 613 * @mnt_userns: user namespace of the mount the inode was found from 614 * @dentry: dentry from which @inode is retrieved 615 * @cpu_caps: vfs capabilities 616 * 617 * Extract the on-exec-apply capability sets for an executable file. 618 * 619 * If the inode has been found through an idmapped mount the user namespace of 620 * the vfsmount must be passed through @mnt_userns. This function will then 621 * take care to map the inode according to @mnt_userns before checking 622 * permissions. On non-idmapped mounts or if permission checking is to be 623 * performed on the raw inode simply passs init_user_ns. 624 */ 625 int get_vfs_caps_from_disk(struct user_namespace *mnt_userns, 626 const struct dentry *dentry, 627 struct cpu_vfs_cap_data *cpu_caps) 628 { 629 struct inode *inode = d_backing_inode(dentry); 630 __u32 magic_etc; 631 unsigned tocopy, i; 632 int size; 633 struct vfs_ns_cap_data data, *nscaps = &data; 634 struct vfs_cap_data *caps = (struct vfs_cap_data *) &data; 635 kuid_t rootkuid; 636 struct user_namespace *fs_ns; 637 638 memset(cpu_caps, 0, sizeof(struct cpu_vfs_cap_data)); 639 640 if (!inode) 641 return -ENODATA; 642 643 fs_ns = inode->i_sb->s_user_ns; 644 size = __vfs_getxattr((struct dentry *)dentry, inode, 645 XATTR_NAME_CAPS, &data, XATTR_CAPS_SZ); 646 if (size == -ENODATA || size == -EOPNOTSUPP) 647 /* no data, that's ok */ 648 return -ENODATA; 649 650 if (size < 0) 651 return size; 652 653 if (size < sizeof(magic_etc)) 654 return -EINVAL; 655 656 cpu_caps->magic_etc = magic_etc = le32_to_cpu(caps->magic_etc); 657 658 rootkuid = make_kuid(fs_ns, 0); 659 switch (magic_etc & VFS_CAP_REVISION_MASK) { 660 case VFS_CAP_REVISION_1: 661 if (size != XATTR_CAPS_SZ_1) 662 return -EINVAL; 663 tocopy = VFS_CAP_U32_1; 664 break; 665 case VFS_CAP_REVISION_2: 666 if (size != XATTR_CAPS_SZ_2) 667 return -EINVAL; 668 tocopy = VFS_CAP_U32_2; 669 break; 670 case VFS_CAP_REVISION_3: 671 if (size != XATTR_CAPS_SZ_3) 672 return -EINVAL; 673 tocopy = VFS_CAP_U32_3; 674 rootkuid = make_kuid(fs_ns, le32_to_cpu(nscaps->rootid)); 675 break; 676 677 default: 678 return -EINVAL; 679 } 680 /* Limit the caps to the mounter of the filesystem 681 * or the more limited uid specified in the xattr. 682 */ 683 rootkuid = kuid_into_mnt(mnt_userns, rootkuid); 684 if (!rootid_owns_currentns(rootkuid)) 685 return -ENODATA; 686 687 CAP_FOR_EACH_U32(i) { 688 if (i >= tocopy) 689 break; 690 cpu_caps->permitted.cap[i] = le32_to_cpu(caps->data[i].permitted); 691 cpu_caps->inheritable.cap[i] = le32_to_cpu(caps->data[i].inheritable); 692 } 693 694 cpu_caps->permitted.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK; 695 cpu_caps->inheritable.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK; 696 697 cpu_caps->rootid = rootkuid; 698 699 return 0; 700 } 701 702 /* 703 * Attempt to get the on-exec apply capability sets for an executable file from 704 * its xattrs and, if present, apply them to the proposed credentials being 705 * constructed by execve(). 706 */ 707 static int get_file_caps(struct linux_binprm *bprm, struct file *file, 708 bool *effective, bool *has_fcap) 709 { 710 int rc = 0; 711 struct cpu_vfs_cap_data vcaps; 712 713 cap_clear(bprm->cred->cap_permitted); 714 715 if (!file_caps_enabled) 716 return 0; 717 718 if (!mnt_may_suid(file->f_path.mnt)) 719 return 0; 720 721 /* 722 * This check is redundant with mnt_may_suid() but is kept to make 723 * explicit that capability bits are limited to s_user_ns and its 724 * descendants. 725 */ 726 if (!current_in_userns(file->f_path.mnt->mnt_sb->s_user_ns)) 727 return 0; 728 729 rc = get_vfs_caps_from_disk(file_mnt_user_ns(file), 730 file->f_path.dentry, &vcaps); 731 if (rc < 0) { 732 if (rc == -EINVAL) 733 printk(KERN_NOTICE "Invalid argument reading file caps for %s\n", 734 bprm->filename); 735 else if (rc == -ENODATA) 736 rc = 0; 737 goto out; 738 } 739 740 rc = bprm_caps_from_vfs_caps(&vcaps, bprm, effective, has_fcap); 741 742 out: 743 if (rc) 744 cap_clear(bprm->cred->cap_permitted); 745 746 return rc; 747 } 748 749 static inline bool root_privileged(void) { return !issecure(SECURE_NOROOT); } 750 751 static inline bool __is_real(kuid_t uid, struct cred *cred) 752 { return uid_eq(cred->uid, uid); } 753 754 static inline bool __is_eff(kuid_t uid, struct cred *cred) 755 { return uid_eq(cred->euid, uid); } 756 757 static inline bool __is_suid(kuid_t uid, struct cred *cred) 758 { return !__is_real(uid, cred) && __is_eff(uid, cred); } 759 760 /* 761 * handle_privileged_root - Handle case of privileged root 762 * @bprm: The execution parameters, including the proposed creds 763 * @has_fcap: Are any file capabilities set? 764 * @effective: Do we have effective root privilege? 765 * @root_uid: This namespace' root UID WRT initial USER namespace 766 * 767 * Handle the case where root is privileged and hasn't been neutered by 768 * SECURE_NOROOT. If file capabilities are set, they won't be combined with 769 * set UID root and nothing is changed. If we are root, cap_permitted is 770 * updated. If we have become set UID root, the effective bit is set. 771 */ 772 static void handle_privileged_root(struct linux_binprm *bprm, bool has_fcap, 773 bool *effective, kuid_t root_uid) 774 { 775 const struct cred *old = current_cred(); 776 struct cred *new = bprm->cred; 777 778 if (!root_privileged()) 779 return; 780 /* 781 * If the legacy file capability is set, then don't set privs 782 * for a setuid root binary run by a non-root user. Do set it 783 * for a root user just to cause least surprise to an admin. 784 */ 785 if (has_fcap && __is_suid(root_uid, new)) { 786 warn_setuid_and_fcaps_mixed(bprm->filename); 787 return; 788 } 789 /* 790 * To support inheritance of root-permissions and suid-root 791 * executables under compatibility mode, we override the 792 * capability sets for the file. 793 */ 794 if (__is_eff(root_uid, new) || __is_real(root_uid, new)) { 795 /* pP' = (cap_bset & ~0) | (pI & ~0) */ 796 new->cap_permitted = cap_combine(old->cap_bset, 797 old->cap_inheritable); 798 } 799 /* 800 * If only the real uid is 0, we do not set the effective bit. 801 */ 802 if (__is_eff(root_uid, new)) 803 *effective = true; 804 } 805 806 #define __cap_gained(field, target, source) \ 807 !cap_issubset(target->cap_##field, source->cap_##field) 808 #define __cap_grew(target, source, cred) \ 809 !cap_issubset(cred->cap_##target, cred->cap_##source) 810 #define __cap_full(field, cred) \ 811 cap_issubset(CAP_FULL_SET, cred->cap_##field) 812 813 static inline bool __is_setuid(struct cred *new, const struct cred *old) 814 { return !uid_eq(new->euid, old->uid); } 815 816 static inline bool __is_setgid(struct cred *new, const struct cred *old) 817 { return !gid_eq(new->egid, old->gid); } 818 819 /* 820 * 1) Audit candidate if current->cap_effective is set 821 * 822 * We do not bother to audit if 3 things are true: 823 * 1) cap_effective has all caps 824 * 2) we became root *OR* are were already root 825 * 3) root is supposed to have all caps (SECURE_NOROOT) 826 * Since this is just a normal root execing a process. 827 * 828 * Number 1 above might fail if you don't have a full bset, but I think 829 * that is interesting information to audit. 830 * 831 * A number of other conditions require logging: 832 * 2) something prevented setuid root getting all caps 833 * 3) non-setuid root gets fcaps 834 * 4) non-setuid root gets ambient 835 */ 836 static inline bool nonroot_raised_pE(struct cred *new, const struct cred *old, 837 kuid_t root, bool has_fcap) 838 { 839 bool ret = false; 840 841 if ((__cap_grew(effective, ambient, new) && 842 !(__cap_full(effective, new) && 843 (__is_eff(root, new) || __is_real(root, new)) && 844 root_privileged())) || 845 (root_privileged() && 846 __is_suid(root, new) && 847 !__cap_full(effective, new)) || 848 (!__is_setuid(new, old) && 849 ((has_fcap && 850 __cap_gained(permitted, new, old)) || 851 __cap_gained(ambient, new, old)))) 852 853 ret = true; 854 855 return ret; 856 } 857 858 /** 859 * cap_bprm_creds_from_file - Set up the proposed credentials for execve(). 860 * @bprm: The execution parameters, including the proposed creds 861 * @file: The file to pull the credentials from 862 * 863 * Set up the proposed credentials for a new execution context being 864 * constructed by execve(). The proposed creds in @bprm->cred is altered, 865 * which won't take effect immediately. Returns 0 if successful, -ve on error. 866 */ 867 int cap_bprm_creds_from_file(struct linux_binprm *bprm, struct file *file) 868 { 869 /* Process setpcap binaries and capabilities for uid 0 */ 870 const struct cred *old = current_cred(); 871 struct cred *new = bprm->cred; 872 bool effective = false, has_fcap = false, is_setid; 873 int ret; 874 kuid_t root_uid; 875 876 if (WARN_ON(!cap_ambient_invariant_ok(old))) 877 return -EPERM; 878 879 ret = get_file_caps(bprm, file, &effective, &has_fcap); 880 if (ret < 0) 881 return ret; 882 883 root_uid = make_kuid(new->user_ns, 0); 884 885 handle_privileged_root(bprm, has_fcap, &effective, root_uid); 886 887 /* if we have fs caps, clear dangerous personality flags */ 888 if (__cap_gained(permitted, new, old)) 889 bprm->per_clear |= PER_CLEAR_ON_SETID; 890 891 /* Don't let someone trace a set[ug]id/setpcap binary with the revised 892 * credentials unless they have the appropriate permit. 893 * 894 * In addition, if NO_NEW_PRIVS, then ensure we get no new privs. 895 */ 896 is_setid = __is_setuid(new, old) || __is_setgid(new, old); 897 898 if ((is_setid || __cap_gained(permitted, new, old)) && 899 ((bprm->unsafe & ~LSM_UNSAFE_PTRACE) || 900 !ptracer_capable(current, new->user_ns))) { 901 /* downgrade; they get no more than they had, and maybe less */ 902 if (!ns_capable(new->user_ns, CAP_SETUID) || 903 (bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS)) { 904 new->euid = new->uid; 905 new->egid = new->gid; 906 } 907 new->cap_permitted = cap_intersect(new->cap_permitted, 908 old->cap_permitted); 909 } 910 911 new->suid = new->fsuid = new->euid; 912 new->sgid = new->fsgid = new->egid; 913 914 /* File caps or setid cancels ambient. */ 915 if (has_fcap || is_setid) 916 cap_clear(new->cap_ambient); 917 918 /* 919 * Now that we've computed pA', update pP' to give: 920 * pP' = (X & fP) | (pI & fI) | pA' 921 */ 922 new->cap_permitted = cap_combine(new->cap_permitted, new->cap_ambient); 923 924 /* 925 * Set pE' = (fE ? pP' : pA'). Because pA' is zero if fE is set, 926 * this is the same as pE' = (fE ? pP' : 0) | pA'. 927 */ 928 if (effective) 929 new->cap_effective = new->cap_permitted; 930 else 931 new->cap_effective = new->cap_ambient; 932 933 if (WARN_ON(!cap_ambient_invariant_ok(new))) 934 return -EPERM; 935 936 if (nonroot_raised_pE(new, old, root_uid, has_fcap)) { 937 ret = audit_log_bprm_fcaps(bprm, new, old); 938 if (ret < 0) 939 return ret; 940 } 941 942 new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS); 943 944 if (WARN_ON(!cap_ambient_invariant_ok(new))) 945 return -EPERM; 946 947 /* Check for privilege-elevated exec. */ 948 if (is_setid || 949 (!__is_real(root_uid, new) && 950 (effective || 951 __cap_grew(permitted, ambient, new)))) 952 bprm->secureexec = 1; 953 954 return 0; 955 } 956 957 /** 958 * cap_inode_setxattr - Determine whether an xattr may be altered 959 * @dentry: The inode/dentry being altered 960 * @name: The name of the xattr to be changed 961 * @value: The value that the xattr will be changed to 962 * @size: The size of value 963 * @flags: The replacement flag 964 * 965 * Determine whether an xattr may be altered or set on an inode, returning 0 if 966 * permission is granted, -ve if denied. 967 * 968 * This is used to make sure security xattrs don't get updated or set by those 969 * who aren't privileged to do so. 970 */ 971 int cap_inode_setxattr(struct dentry *dentry, const char *name, 972 const void *value, size_t size, int flags) 973 { 974 struct user_namespace *user_ns = dentry->d_sb->s_user_ns; 975 976 /* Ignore non-security xattrs */ 977 if (strncmp(name, XATTR_SECURITY_PREFIX, 978 XATTR_SECURITY_PREFIX_LEN) != 0) 979 return 0; 980 981 /* 982 * For XATTR_NAME_CAPS the check will be done in 983 * cap_convert_nscap(), called by setxattr() 984 */ 985 if (strcmp(name, XATTR_NAME_CAPS) == 0) 986 return 0; 987 988 if (!ns_capable(user_ns, CAP_SYS_ADMIN)) 989 return -EPERM; 990 return 0; 991 } 992 993 /** 994 * cap_inode_removexattr - Determine whether an xattr may be removed 995 * 996 * @mnt_userns: User namespace of the mount the inode was found from 997 * @dentry: The inode/dentry being altered 998 * @name: The name of the xattr to be changed 999 * 1000 * Determine whether an xattr may be removed from an inode, returning 0 if 1001 * permission is granted, -ve if denied. 1002 * 1003 * If the inode has been found through an idmapped mount the user namespace of 1004 * the vfsmount must be passed through @mnt_userns. This function will then 1005 * take care to map the inode according to @mnt_userns before checking 1006 * permissions. On non-idmapped mounts or if permission checking is to be 1007 * performed on the raw inode simply passs init_user_ns. 1008 * 1009 * This is used to make sure security xattrs don't get removed by those who 1010 * aren't privileged to remove them. 1011 */ 1012 int cap_inode_removexattr(struct user_namespace *mnt_userns, 1013 struct dentry *dentry, const char *name) 1014 { 1015 struct user_namespace *user_ns = dentry->d_sb->s_user_ns; 1016 1017 /* Ignore non-security xattrs */ 1018 if (strncmp(name, XATTR_SECURITY_PREFIX, 1019 XATTR_SECURITY_PREFIX_LEN) != 0) 1020 return 0; 1021 1022 if (strcmp(name, XATTR_NAME_CAPS) == 0) { 1023 /* security.capability gets namespaced */ 1024 struct inode *inode = d_backing_inode(dentry); 1025 if (!inode) 1026 return -EINVAL; 1027 if (!capable_wrt_inode_uidgid(mnt_userns, inode, CAP_SETFCAP)) 1028 return -EPERM; 1029 return 0; 1030 } 1031 1032 if (!ns_capable(user_ns, CAP_SYS_ADMIN)) 1033 return -EPERM; 1034 return 0; 1035 } 1036 1037 /* 1038 * cap_emulate_setxuid() fixes the effective / permitted capabilities of 1039 * a process after a call to setuid, setreuid, or setresuid. 1040 * 1041 * 1) When set*uiding _from_ one of {r,e,s}uid == 0 _to_ all of 1042 * {r,e,s}uid != 0, the permitted and effective capabilities are 1043 * cleared. 1044 * 1045 * 2) When set*uiding _from_ euid == 0 _to_ euid != 0, the effective 1046 * capabilities of the process are cleared. 1047 * 1048 * 3) When set*uiding _from_ euid != 0 _to_ euid == 0, the effective 1049 * capabilities are set to the permitted capabilities. 1050 * 1051 * fsuid is handled elsewhere. fsuid == 0 and {r,e,s}uid!= 0 should 1052 * never happen. 1053 * 1054 * -astor 1055 * 1056 * cevans - New behaviour, Oct '99 1057 * A process may, via prctl(), elect to keep its capabilities when it 1058 * calls setuid() and switches away from uid==0. Both permitted and 1059 * effective sets will be retained. 1060 * Without this change, it was impossible for a daemon to drop only some 1061 * of its privilege. The call to setuid(!=0) would drop all privileges! 1062 * Keeping uid 0 is not an option because uid 0 owns too many vital 1063 * files.. 1064 * Thanks to Olaf Kirch and Peter Benie for spotting this. 1065 */ 1066 static inline void cap_emulate_setxuid(struct cred *new, const struct cred *old) 1067 { 1068 kuid_t root_uid = make_kuid(old->user_ns, 0); 1069 1070 if ((uid_eq(old->uid, root_uid) || 1071 uid_eq(old->euid, root_uid) || 1072 uid_eq(old->suid, root_uid)) && 1073 (!uid_eq(new->uid, root_uid) && 1074 !uid_eq(new->euid, root_uid) && 1075 !uid_eq(new->suid, root_uid))) { 1076 if (!issecure(SECURE_KEEP_CAPS)) { 1077 cap_clear(new->cap_permitted); 1078 cap_clear(new->cap_effective); 1079 } 1080 1081 /* 1082 * Pre-ambient programs expect setresuid to nonroot followed 1083 * by exec to drop capabilities. We should make sure that 1084 * this remains the case. 1085 */ 1086 cap_clear(new->cap_ambient); 1087 } 1088 if (uid_eq(old->euid, root_uid) && !uid_eq(new->euid, root_uid)) 1089 cap_clear(new->cap_effective); 1090 if (!uid_eq(old->euid, root_uid) && uid_eq(new->euid, root_uid)) 1091 new->cap_effective = new->cap_permitted; 1092 } 1093 1094 /** 1095 * cap_task_fix_setuid - Fix up the results of setuid() call 1096 * @new: The proposed credentials 1097 * @old: The current task's current credentials 1098 * @flags: Indications of what has changed 1099 * 1100 * Fix up the results of setuid() call before the credential changes are 1101 * actually applied, returning 0 to grant the changes, -ve to deny them. 1102 */ 1103 int cap_task_fix_setuid(struct cred *new, const struct cred *old, int flags) 1104 { 1105 switch (flags) { 1106 case LSM_SETID_RE: 1107 case LSM_SETID_ID: 1108 case LSM_SETID_RES: 1109 /* juggle the capabilities to follow [RES]UID changes unless 1110 * otherwise suppressed */ 1111 if (!issecure(SECURE_NO_SETUID_FIXUP)) 1112 cap_emulate_setxuid(new, old); 1113 break; 1114 1115 case LSM_SETID_FS: 1116 /* juggle the capabilties to follow FSUID changes, unless 1117 * otherwise suppressed 1118 * 1119 * FIXME - is fsuser used for all CAP_FS_MASK capabilities? 1120 * if not, we might be a bit too harsh here. 1121 */ 1122 if (!issecure(SECURE_NO_SETUID_FIXUP)) { 1123 kuid_t root_uid = make_kuid(old->user_ns, 0); 1124 if (uid_eq(old->fsuid, root_uid) && !uid_eq(new->fsuid, root_uid)) 1125 new->cap_effective = 1126 cap_drop_fs_set(new->cap_effective); 1127 1128 if (!uid_eq(old->fsuid, root_uid) && uid_eq(new->fsuid, root_uid)) 1129 new->cap_effective = 1130 cap_raise_fs_set(new->cap_effective, 1131 new->cap_permitted); 1132 } 1133 break; 1134 1135 default: 1136 return -EINVAL; 1137 } 1138 1139 return 0; 1140 } 1141 1142 /* 1143 * Rationale: code calling task_setscheduler, task_setioprio, and 1144 * task_setnice, assumes that 1145 * . if capable(cap_sys_nice), then those actions should be allowed 1146 * . if not capable(cap_sys_nice), but acting on your own processes, 1147 * then those actions should be allowed 1148 * This is insufficient now since you can call code without suid, but 1149 * yet with increased caps. 1150 * So we check for increased caps on the target process. 1151 */ 1152 static int cap_safe_nice(struct task_struct *p) 1153 { 1154 int is_subset, ret = 0; 1155 1156 rcu_read_lock(); 1157 is_subset = cap_issubset(__task_cred(p)->cap_permitted, 1158 current_cred()->cap_permitted); 1159 if (!is_subset && !ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) 1160 ret = -EPERM; 1161 rcu_read_unlock(); 1162 1163 return ret; 1164 } 1165 1166 /** 1167 * cap_task_setscheduler - Detemine if scheduler policy change is permitted 1168 * @p: The task to affect 1169 * 1170 * Detemine if the requested scheduler policy change is permitted for the 1171 * specified task, returning 0 if permission is granted, -ve if denied. 1172 */ 1173 int cap_task_setscheduler(struct task_struct *p) 1174 { 1175 return cap_safe_nice(p); 1176 } 1177 1178 /** 1179 * cap_task_ioprio - Detemine if I/O priority change is permitted 1180 * @p: The task to affect 1181 * @ioprio: The I/O priority to set 1182 * 1183 * Detemine if the requested I/O priority change is permitted for the specified 1184 * task, returning 0 if permission is granted, -ve if denied. 1185 */ 1186 int cap_task_setioprio(struct task_struct *p, int ioprio) 1187 { 1188 return cap_safe_nice(p); 1189 } 1190 1191 /** 1192 * cap_task_ioprio - Detemine if task priority change is permitted 1193 * @p: The task to affect 1194 * @nice: The nice value to set 1195 * 1196 * Detemine if the requested task priority change is permitted for the 1197 * specified task, returning 0 if permission is granted, -ve if denied. 1198 */ 1199 int cap_task_setnice(struct task_struct *p, int nice) 1200 { 1201 return cap_safe_nice(p); 1202 } 1203 1204 /* 1205 * Implement PR_CAPBSET_DROP. Attempt to remove the specified capability from 1206 * the current task's bounding set. Returns 0 on success, -ve on error. 1207 */ 1208 static int cap_prctl_drop(unsigned long cap) 1209 { 1210 struct cred *new; 1211 1212 if (!ns_capable(current_user_ns(), CAP_SETPCAP)) 1213 return -EPERM; 1214 if (!cap_valid(cap)) 1215 return -EINVAL; 1216 1217 new = prepare_creds(); 1218 if (!new) 1219 return -ENOMEM; 1220 cap_lower(new->cap_bset, cap); 1221 return commit_creds(new); 1222 } 1223 1224 /** 1225 * cap_task_prctl - Implement process control functions for this security module 1226 * @option: The process control function requested 1227 * @arg2, @arg3, @arg4, @arg5: The argument data for this function 1228 * 1229 * Allow process control functions (sys_prctl()) to alter capabilities; may 1230 * also deny access to other functions not otherwise implemented here. 1231 * 1232 * Returns 0 or +ve on success, -ENOSYS if this function is not implemented 1233 * here, other -ve on error. If -ENOSYS is returned, sys_prctl() and other LSM 1234 * modules will consider performing the function. 1235 */ 1236 int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3, 1237 unsigned long arg4, unsigned long arg5) 1238 { 1239 const struct cred *old = current_cred(); 1240 struct cred *new; 1241 1242 switch (option) { 1243 case PR_CAPBSET_READ: 1244 if (!cap_valid(arg2)) 1245 return -EINVAL; 1246 return !!cap_raised(old->cap_bset, arg2); 1247 1248 case PR_CAPBSET_DROP: 1249 return cap_prctl_drop(arg2); 1250 1251 /* 1252 * The next four prctl's remain to assist with transitioning a 1253 * system from legacy UID=0 based privilege (when filesystem 1254 * capabilities are not in use) to a system using filesystem 1255 * capabilities only - as the POSIX.1e draft intended. 1256 * 1257 * Note: 1258 * 1259 * PR_SET_SECUREBITS = 1260 * issecure_mask(SECURE_KEEP_CAPS_LOCKED) 1261 * | issecure_mask(SECURE_NOROOT) 1262 * | issecure_mask(SECURE_NOROOT_LOCKED) 1263 * | issecure_mask(SECURE_NO_SETUID_FIXUP) 1264 * | issecure_mask(SECURE_NO_SETUID_FIXUP_LOCKED) 1265 * 1266 * will ensure that the current process and all of its 1267 * children will be locked into a pure 1268 * capability-based-privilege environment. 1269 */ 1270 case PR_SET_SECUREBITS: 1271 if ((((old->securebits & SECURE_ALL_LOCKS) >> 1) 1272 & (old->securebits ^ arg2)) /*[1]*/ 1273 || ((old->securebits & SECURE_ALL_LOCKS & ~arg2)) /*[2]*/ 1274 || (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS)) /*[3]*/ 1275 || (cap_capable(current_cred(), 1276 current_cred()->user_ns, 1277 CAP_SETPCAP, 1278 CAP_OPT_NONE) != 0) /*[4]*/ 1279 /* 1280 * [1] no changing of bits that are locked 1281 * [2] no unlocking of locks 1282 * [3] no setting of unsupported bits 1283 * [4] doing anything requires privilege (go read about 1284 * the "sendmail capabilities bug") 1285 */ 1286 ) 1287 /* cannot change a locked bit */ 1288 return -EPERM; 1289 1290 new = prepare_creds(); 1291 if (!new) 1292 return -ENOMEM; 1293 new->securebits = arg2; 1294 return commit_creds(new); 1295 1296 case PR_GET_SECUREBITS: 1297 return old->securebits; 1298 1299 case PR_GET_KEEPCAPS: 1300 return !!issecure(SECURE_KEEP_CAPS); 1301 1302 case PR_SET_KEEPCAPS: 1303 if (arg2 > 1) /* Note, we rely on arg2 being unsigned here */ 1304 return -EINVAL; 1305 if (issecure(SECURE_KEEP_CAPS_LOCKED)) 1306 return -EPERM; 1307 1308 new = prepare_creds(); 1309 if (!new) 1310 return -ENOMEM; 1311 if (arg2) 1312 new->securebits |= issecure_mask(SECURE_KEEP_CAPS); 1313 else 1314 new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS); 1315 return commit_creds(new); 1316 1317 case PR_CAP_AMBIENT: 1318 if (arg2 == PR_CAP_AMBIENT_CLEAR_ALL) { 1319 if (arg3 | arg4 | arg5) 1320 return -EINVAL; 1321 1322 new = prepare_creds(); 1323 if (!new) 1324 return -ENOMEM; 1325 cap_clear(new->cap_ambient); 1326 return commit_creds(new); 1327 } 1328 1329 if (((!cap_valid(arg3)) | arg4 | arg5)) 1330 return -EINVAL; 1331 1332 if (arg2 == PR_CAP_AMBIENT_IS_SET) { 1333 return !!cap_raised(current_cred()->cap_ambient, arg3); 1334 } else if (arg2 != PR_CAP_AMBIENT_RAISE && 1335 arg2 != PR_CAP_AMBIENT_LOWER) { 1336 return -EINVAL; 1337 } else { 1338 if (arg2 == PR_CAP_AMBIENT_RAISE && 1339 (!cap_raised(current_cred()->cap_permitted, arg3) || 1340 !cap_raised(current_cred()->cap_inheritable, 1341 arg3) || 1342 issecure(SECURE_NO_CAP_AMBIENT_RAISE))) 1343 return -EPERM; 1344 1345 new = prepare_creds(); 1346 if (!new) 1347 return -ENOMEM; 1348 if (arg2 == PR_CAP_AMBIENT_RAISE) 1349 cap_raise(new->cap_ambient, arg3); 1350 else 1351 cap_lower(new->cap_ambient, arg3); 1352 return commit_creds(new); 1353 } 1354 1355 default: 1356 /* No functionality available - continue with default */ 1357 return -ENOSYS; 1358 } 1359 } 1360 1361 /** 1362 * cap_vm_enough_memory - Determine whether a new virtual mapping is permitted 1363 * @mm: The VM space in which the new mapping is to be made 1364 * @pages: The size of the mapping 1365 * 1366 * Determine whether the allocation of a new virtual mapping by the current 1367 * task is permitted, returning 1 if permission is granted, 0 if not. 1368 */ 1369 int cap_vm_enough_memory(struct mm_struct *mm, long pages) 1370 { 1371 int cap_sys_admin = 0; 1372 1373 if (cap_capable(current_cred(), &init_user_ns, 1374 CAP_SYS_ADMIN, CAP_OPT_NOAUDIT) == 0) 1375 cap_sys_admin = 1; 1376 1377 return cap_sys_admin; 1378 } 1379 1380 /* 1381 * cap_mmap_addr - check if able to map given addr 1382 * @addr: address attempting to be mapped 1383 * 1384 * If the process is attempting to map memory below dac_mmap_min_addr they need 1385 * CAP_SYS_RAWIO. The other parameters to this function are unused by the 1386 * capability security module. Returns 0 if this mapping should be allowed 1387 * -EPERM if not. 1388 */ 1389 int cap_mmap_addr(unsigned long addr) 1390 { 1391 int ret = 0; 1392 1393 if (addr < dac_mmap_min_addr) { 1394 ret = cap_capable(current_cred(), &init_user_ns, CAP_SYS_RAWIO, 1395 CAP_OPT_NONE); 1396 /* set PF_SUPERPRIV if it turns out we allow the low mmap */ 1397 if (ret == 0) 1398 current->flags |= PF_SUPERPRIV; 1399 } 1400 return ret; 1401 } 1402 1403 int cap_mmap_file(struct file *file, unsigned long reqprot, 1404 unsigned long prot, unsigned long flags) 1405 { 1406 return 0; 1407 } 1408 1409 #ifdef CONFIG_SECURITY 1410 1411 static struct security_hook_list capability_hooks[] __lsm_ro_after_init = { 1412 LSM_HOOK_INIT(capable, cap_capable), 1413 LSM_HOOK_INIT(settime, cap_settime), 1414 LSM_HOOK_INIT(ptrace_access_check, cap_ptrace_access_check), 1415 LSM_HOOK_INIT(ptrace_traceme, cap_ptrace_traceme), 1416 LSM_HOOK_INIT(capget, cap_capget), 1417 LSM_HOOK_INIT(capset, cap_capset), 1418 LSM_HOOK_INIT(bprm_creds_from_file, cap_bprm_creds_from_file), 1419 LSM_HOOK_INIT(inode_need_killpriv, cap_inode_need_killpriv), 1420 LSM_HOOK_INIT(inode_killpriv, cap_inode_killpriv), 1421 LSM_HOOK_INIT(inode_getsecurity, cap_inode_getsecurity), 1422 LSM_HOOK_INIT(mmap_addr, cap_mmap_addr), 1423 LSM_HOOK_INIT(mmap_file, cap_mmap_file), 1424 LSM_HOOK_INIT(task_fix_setuid, cap_task_fix_setuid), 1425 LSM_HOOK_INIT(task_prctl, cap_task_prctl), 1426 LSM_HOOK_INIT(task_setscheduler, cap_task_setscheduler), 1427 LSM_HOOK_INIT(task_setioprio, cap_task_setioprio), 1428 LSM_HOOK_INIT(task_setnice, cap_task_setnice), 1429 LSM_HOOK_INIT(vm_enough_memory, cap_vm_enough_memory), 1430 }; 1431 1432 static int __init capability_init(void) 1433 { 1434 security_add_hooks(capability_hooks, ARRAY_SIZE(capability_hooks), 1435 "capability"); 1436 return 0; 1437 } 1438 1439 DEFINE_LSM(capability) = { 1440 .name = "capability", 1441 .order = LSM_ORDER_FIRST, 1442 .init = capability_init, 1443 }; 1444 1445 #endif /* CONFIG_SECURITY */ 1446