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 u32 nsmagic, magic; 384 uid_t root, mappedroot; 385 char *tmpbuf = NULL; 386 struct vfs_cap_data *cap; 387 struct vfs_ns_cap_data *nscap = NULL; 388 struct dentry *dentry; 389 struct user_namespace *fs_ns; 390 391 if (strcmp(name, "capability") != 0) 392 return -EOPNOTSUPP; 393 394 dentry = d_find_any_alias(inode); 395 if (!dentry) 396 return -EINVAL; 397 398 size = sizeof(struct vfs_ns_cap_data); 399 ret = (int)vfs_getxattr_alloc(mnt_userns, dentry, XATTR_NAME_CAPS, 400 &tmpbuf, size, GFP_NOFS); 401 dput(dentry); 402 403 if (ret < 0) 404 return ret; 405 406 fs_ns = inode->i_sb->s_user_ns; 407 cap = (struct vfs_cap_data *) tmpbuf; 408 if (is_v2header((size_t) ret, cap)) { 409 root = 0; 410 } else if (is_v3header((size_t) ret, cap)) { 411 nscap = (struct vfs_ns_cap_data *) tmpbuf; 412 root = le32_to_cpu(nscap->rootid); 413 } else { 414 size = -EINVAL; 415 goto out_free; 416 } 417 418 kroot = make_kuid(fs_ns, root); 419 420 /* If this is an idmapped mount shift the kuid. */ 421 kroot = kuid_into_mnt(mnt_userns, kroot); 422 423 /* If the root kuid maps to a valid uid in current ns, then return 424 * this as a nscap. */ 425 mappedroot = from_kuid(current_user_ns(), kroot); 426 if (mappedroot != (uid_t)-1 && mappedroot != (uid_t)0) { 427 size = sizeof(struct vfs_ns_cap_data); 428 if (alloc) { 429 if (!nscap) { 430 /* v2 -> v3 conversion */ 431 nscap = kzalloc(size, GFP_ATOMIC); 432 if (!nscap) { 433 size = -ENOMEM; 434 goto out_free; 435 } 436 nsmagic = VFS_CAP_REVISION_3; 437 magic = le32_to_cpu(cap->magic_etc); 438 if (magic & VFS_CAP_FLAGS_EFFECTIVE) 439 nsmagic |= VFS_CAP_FLAGS_EFFECTIVE; 440 memcpy(&nscap->data, &cap->data, sizeof(__le32) * 2 * VFS_CAP_U32); 441 nscap->magic_etc = cpu_to_le32(nsmagic); 442 } else { 443 /* use allocated v3 buffer */ 444 tmpbuf = NULL; 445 } 446 nscap->rootid = cpu_to_le32(mappedroot); 447 *buffer = nscap; 448 } 449 goto out_free; 450 } 451 452 if (!rootid_owns_currentns(kroot)) { 453 size = -EOVERFLOW; 454 goto out_free; 455 } 456 457 /* This comes from a parent namespace. Return as a v2 capability */ 458 size = sizeof(struct vfs_cap_data); 459 if (alloc) { 460 if (nscap) { 461 /* v3 -> v2 conversion */ 462 cap = kzalloc(size, GFP_ATOMIC); 463 if (!cap) { 464 size = -ENOMEM; 465 goto out_free; 466 } 467 magic = VFS_CAP_REVISION_2; 468 nsmagic = le32_to_cpu(nscap->magic_etc); 469 if (nsmagic & VFS_CAP_FLAGS_EFFECTIVE) 470 magic |= VFS_CAP_FLAGS_EFFECTIVE; 471 memcpy(&cap->data, &nscap->data, sizeof(__le32) * 2 * VFS_CAP_U32); 472 cap->magic_etc = cpu_to_le32(magic); 473 } else { 474 /* use unconverted v2 */ 475 tmpbuf = NULL; 476 } 477 *buffer = cap; 478 } 479 out_free: 480 kfree(tmpbuf); 481 return size; 482 } 483 484 /** 485 * rootid_from_xattr - translate root uid of vfs caps 486 * 487 * @value: vfs caps value which may be modified by this function 488 * @size: size of @ivalue 489 * @task_ns: user namespace of the caller 490 * @mnt_userns: user namespace of the mount the inode was found from 491 * 492 * If the inode has been found through an idmapped mount the user namespace of 493 * the vfsmount must be passed through @mnt_userns. This function will then 494 * take care to map the inode according to @mnt_userns before checking 495 * permissions. On non-idmapped mounts or if permission checking is to be 496 * performed on the raw inode simply passs init_user_ns. 497 */ 498 static kuid_t rootid_from_xattr(const void *value, size_t size, 499 struct user_namespace *task_ns, 500 struct user_namespace *mnt_userns) 501 { 502 const struct vfs_ns_cap_data *nscap = value; 503 kuid_t rootkid; 504 uid_t rootid = 0; 505 506 if (size == XATTR_CAPS_SZ_3) 507 rootid = le32_to_cpu(nscap->rootid); 508 509 rootkid = make_kuid(task_ns, rootid); 510 return kuid_from_mnt(mnt_userns, rootkid); 511 } 512 513 static bool validheader(size_t size, const struct vfs_cap_data *cap) 514 { 515 return is_v2header(size, cap) || is_v3header(size, cap); 516 } 517 518 /** 519 * cap_convert_nscap - check vfs caps 520 * 521 * @mnt_userns: user namespace of the mount the inode was found from 522 * @dentry: used to retrieve inode to check permissions on 523 * @ivalue: vfs caps value which may be modified by this function 524 * @size: size of @ivalue 525 * 526 * User requested a write of security.capability. If needed, update the 527 * xattr to change from v2 to v3, or to fixup the v3 rootid. 528 * 529 * If the inode has been found through an idmapped mount the user namespace of 530 * the vfsmount must be passed through @mnt_userns. This function will then 531 * take care to map the inode according to @mnt_userns before checking 532 * permissions. On non-idmapped mounts or if permission checking is to be 533 * performed on the raw inode simply passs init_user_ns. 534 * 535 * If all is ok, we return the new size, on error return < 0. 536 */ 537 int cap_convert_nscap(struct user_namespace *mnt_userns, struct dentry *dentry, 538 const void **ivalue, size_t size) 539 { 540 struct vfs_ns_cap_data *nscap; 541 uid_t nsrootid; 542 const struct vfs_cap_data *cap = *ivalue; 543 __u32 magic, nsmagic; 544 struct inode *inode = d_backing_inode(dentry); 545 struct user_namespace *task_ns = current_user_ns(), 546 *fs_ns = inode->i_sb->s_user_ns, 547 *ancestor; 548 kuid_t rootid; 549 size_t newsize; 550 551 if (!*ivalue) 552 return -EINVAL; 553 if (!validheader(size, cap)) 554 return -EINVAL; 555 if (!capable_wrt_inode_uidgid(mnt_userns, inode, CAP_SETFCAP)) 556 return -EPERM; 557 if (size == XATTR_CAPS_SZ_2 && (mnt_userns == &init_user_ns)) 558 if (ns_capable(inode->i_sb->s_user_ns, CAP_SETFCAP)) 559 /* user is privileged, just write the v2 */ 560 return size; 561 562 rootid = rootid_from_xattr(*ivalue, size, task_ns, mnt_userns); 563 if (!uid_valid(rootid)) 564 return -EINVAL; 565 566 nsrootid = from_kuid(fs_ns, rootid); 567 if (nsrootid == -1) 568 return -EINVAL; 569 570 /* 571 * Do not allow allow adding a v3 filesystem capability xattr 572 * if the rootid field is ambiguous. 573 */ 574 for (ancestor = task_ns->parent; ancestor; ancestor = ancestor->parent) { 575 if (from_kuid(ancestor, rootid) == 0) 576 return -EINVAL; 577 } 578 579 newsize = sizeof(struct vfs_ns_cap_data); 580 nscap = kmalloc(newsize, GFP_ATOMIC); 581 if (!nscap) 582 return -ENOMEM; 583 nscap->rootid = cpu_to_le32(nsrootid); 584 nsmagic = VFS_CAP_REVISION_3; 585 magic = le32_to_cpu(cap->magic_etc); 586 if (magic & VFS_CAP_FLAGS_EFFECTIVE) 587 nsmagic |= VFS_CAP_FLAGS_EFFECTIVE; 588 nscap->magic_etc = cpu_to_le32(nsmagic); 589 memcpy(&nscap->data, &cap->data, sizeof(__le32) * 2 * VFS_CAP_U32); 590 591 *ivalue = nscap; 592 return newsize; 593 } 594 595 /* 596 * Calculate the new process capability sets from the capability sets attached 597 * to a file. 598 */ 599 static inline int bprm_caps_from_vfs_caps(struct cpu_vfs_cap_data *caps, 600 struct linux_binprm *bprm, 601 bool *effective, 602 bool *has_fcap) 603 { 604 struct cred *new = bprm->cred; 605 unsigned i; 606 int ret = 0; 607 608 if (caps->magic_etc & VFS_CAP_FLAGS_EFFECTIVE) 609 *effective = true; 610 611 if (caps->magic_etc & VFS_CAP_REVISION_MASK) 612 *has_fcap = true; 613 614 CAP_FOR_EACH_U32(i) { 615 __u32 permitted = caps->permitted.cap[i]; 616 __u32 inheritable = caps->inheritable.cap[i]; 617 618 /* 619 * pP' = (X & fP) | (pI & fI) 620 * The addition of pA' is handled later. 621 */ 622 new->cap_permitted.cap[i] = 623 (new->cap_bset.cap[i] & permitted) | 624 (new->cap_inheritable.cap[i] & inheritable); 625 626 if (permitted & ~new->cap_permitted.cap[i]) 627 /* insufficient to execute correctly */ 628 ret = -EPERM; 629 } 630 631 /* 632 * For legacy apps, with no internal support for recognizing they 633 * do not have enough capabilities, we return an error if they are 634 * missing some "forced" (aka file-permitted) capabilities. 635 */ 636 return *effective ? ret : 0; 637 } 638 639 /** 640 * get_vfs_caps_from_disk - retrieve vfs caps from disk 641 * 642 * @mnt_userns: user namespace of the mount the inode was found from 643 * @dentry: dentry from which @inode is retrieved 644 * @cpu_caps: vfs capabilities 645 * 646 * Extract the on-exec-apply capability sets for an executable file. 647 * 648 * If the inode has been found through an idmapped mount the user namespace of 649 * the vfsmount must be passed through @mnt_userns. This function will then 650 * take care to map the inode according to @mnt_userns before checking 651 * permissions. On non-idmapped mounts or if permission checking is to be 652 * performed on the raw inode simply passs init_user_ns. 653 */ 654 int get_vfs_caps_from_disk(struct user_namespace *mnt_userns, 655 const struct dentry *dentry, 656 struct cpu_vfs_cap_data *cpu_caps) 657 { 658 struct inode *inode = d_backing_inode(dentry); 659 __u32 magic_etc; 660 unsigned tocopy, i; 661 int size; 662 struct vfs_ns_cap_data data, *nscaps = &data; 663 struct vfs_cap_data *caps = (struct vfs_cap_data *) &data; 664 kuid_t rootkuid; 665 struct user_namespace *fs_ns; 666 667 memset(cpu_caps, 0, sizeof(struct cpu_vfs_cap_data)); 668 669 if (!inode) 670 return -ENODATA; 671 672 fs_ns = inode->i_sb->s_user_ns; 673 size = __vfs_getxattr((struct dentry *)dentry, inode, 674 XATTR_NAME_CAPS, &data, XATTR_CAPS_SZ); 675 if (size == -ENODATA || size == -EOPNOTSUPP) 676 /* no data, that's ok */ 677 return -ENODATA; 678 679 if (size < 0) 680 return size; 681 682 if (size < sizeof(magic_etc)) 683 return -EINVAL; 684 685 cpu_caps->magic_etc = magic_etc = le32_to_cpu(caps->magic_etc); 686 687 rootkuid = make_kuid(fs_ns, 0); 688 switch (magic_etc & VFS_CAP_REVISION_MASK) { 689 case VFS_CAP_REVISION_1: 690 if (size != XATTR_CAPS_SZ_1) 691 return -EINVAL; 692 tocopy = VFS_CAP_U32_1; 693 break; 694 case VFS_CAP_REVISION_2: 695 if (size != XATTR_CAPS_SZ_2) 696 return -EINVAL; 697 tocopy = VFS_CAP_U32_2; 698 break; 699 case VFS_CAP_REVISION_3: 700 if (size != XATTR_CAPS_SZ_3) 701 return -EINVAL; 702 tocopy = VFS_CAP_U32_3; 703 rootkuid = make_kuid(fs_ns, le32_to_cpu(nscaps->rootid)); 704 break; 705 706 default: 707 return -EINVAL; 708 } 709 /* Limit the caps to the mounter of the filesystem 710 * or the more limited uid specified in the xattr. 711 */ 712 rootkuid = kuid_into_mnt(mnt_userns, rootkuid); 713 if (!rootid_owns_currentns(rootkuid)) 714 return -ENODATA; 715 716 CAP_FOR_EACH_U32(i) { 717 if (i >= tocopy) 718 break; 719 cpu_caps->permitted.cap[i] = le32_to_cpu(caps->data[i].permitted); 720 cpu_caps->inheritable.cap[i] = le32_to_cpu(caps->data[i].inheritable); 721 } 722 723 cpu_caps->permitted.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK; 724 cpu_caps->inheritable.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK; 725 726 cpu_caps->rootid = rootkuid; 727 728 return 0; 729 } 730 731 /* 732 * Attempt to get the on-exec apply capability sets for an executable file from 733 * its xattrs and, if present, apply them to the proposed credentials being 734 * constructed by execve(). 735 */ 736 static int get_file_caps(struct linux_binprm *bprm, struct file *file, 737 bool *effective, bool *has_fcap) 738 { 739 int rc = 0; 740 struct cpu_vfs_cap_data vcaps; 741 742 cap_clear(bprm->cred->cap_permitted); 743 744 if (!file_caps_enabled) 745 return 0; 746 747 if (!mnt_may_suid(file->f_path.mnt)) 748 return 0; 749 750 /* 751 * This check is redundant with mnt_may_suid() but is kept to make 752 * explicit that capability bits are limited to s_user_ns and its 753 * descendants. 754 */ 755 if (!current_in_userns(file->f_path.mnt->mnt_sb->s_user_ns)) 756 return 0; 757 758 rc = get_vfs_caps_from_disk(file_mnt_user_ns(file), 759 file->f_path.dentry, &vcaps); 760 if (rc < 0) { 761 if (rc == -EINVAL) 762 printk(KERN_NOTICE "Invalid argument reading file caps for %s\n", 763 bprm->filename); 764 else if (rc == -ENODATA) 765 rc = 0; 766 goto out; 767 } 768 769 rc = bprm_caps_from_vfs_caps(&vcaps, bprm, effective, has_fcap); 770 771 out: 772 if (rc) 773 cap_clear(bprm->cred->cap_permitted); 774 775 return rc; 776 } 777 778 static inline bool root_privileged(void) { return !issecure(SECURE_NOROOT); } 779 780 static inline bool __is_real(kuid_t uid, struct cred *cred) 781 { return uid_eq(cred->uid, uid); } 782 783 static inline bool __is_eff(kuid_t uid, struct cred *cred) 784 { return uid_eq(cred->euid, uid); } 785 786 static inline bool __is_suid(kuid_t uid, struct cred *cred) 787 { return !__is_real(uid, cred) && __is_eff(uid, cred); } 788 789 /* 790 * handle_privileged_root - Handle case of privileged root 791 * @bprm: The execution parameters, including the proposed creds 792 * @has_fcap: Are any file capabilities set? 793 * @effective: Do we have effective root privilege? 794 * @root_uid: This namespace' root UID WRT initial USER namespace 795 * 796 * Handle the case where root is privileged and hasn't been neutered by 797 * SECURE_NOROOT. If file capabilities are set, they won't be combined with 798 * set UID root and nothing is changed. If we are root, cap_permitted is 799 * updated. If we have become set UID root, the effective bit is set. 800 */ 801 static void handle_privileged_root(struct linux_binprm *bprm, bool has_fcap, 802 bool *effective, kuid_t root_uid) 803 { 804 const struct cred *old = current_cred(); 805 struct cred *new = bprm->cred; 806 807 if (!root_privileged()) 808 return; 809 /* 810 * If the legacy file capability is set, then don't set privs 811 * for a setuid root binary run by a non-root user. Do set it 812 * for a root user just to cause least surprise to an admin. 813 */ 814 if (has_fcap && __is_suid(root_uid, new)) { 815 warn_setuid_and_fcaps_mixed(bprm->filename); 816 return; 817 } 818 /* 819 * To support inheritance of root-permissions and suid-root 820 * executables under compatibility mode, we override the 821 * capability sets for the file. 822 */ 823 if (__is_eff(root_uid, new) || __is_real(root_uid, new)) { 824 /* pP' = (cap_bset & ~0) | (pI & ~0) */ 825 new->cap_permitted = cap_combine(old->cap_bset, 826 old->cap_inheritable); 827 } 828 /* 829 * If only the real uid is 0, we do not set the effective bit. 830 */ 831 if (__is_eff(root_uid, new)) 832 *effective = true; 833 } 834 835 #define __cap_gained(field, target, source) \ 836 !cap_issubset(target->cap_##field, source->cap_##field) 837 #define __cap_grew(target, source, cred) \ 838 !cap_issubset(cred->cap_##target, cred->cap_##source) 839 #define __cap_full(field, cred) \ 840 cap_issubset(CAP_FULL_SET, cred->cap_##field) 841 842 static inline bool __is_setuid(struct cred *new, const struct cred *old) 843 { return !uid_eq(new->euid, old->uid); } 844 845 static inline bool __is_setgid(struct cred *new, const struct cred *old) 846 { return !gid_eq(new->egid, old->gid); } 847 848 /* 849 * 1) Audit candidate if current->cap_effective is set 850 * 851 * We do not bother to audit if 3 things are true: 852 * 1) cap_effective has all caps 853 * 2) we became root *OR* are were already root 854 * 3) root is supposed to have all caps (SECURE_NOROOT) 855 * Since this is just a normal root execing a process. 856 * 857 * Number 1 above might fail if you don't have a full bset, but I think 858 * that is interesting information to audit. 859 * 860 * A number of other conditions require logging: 861 * 2) something prevented setuid root getting all caps 862 * 3) non-setuid root gets fcaps 863 * 4) non-setuid root gets ambient 864 */ 865 static inline bool nonroot_raised_pE(struct cred *new, const struct cred *old, 866 kuid_t root, bool has_fcap) 867 { 868 bool ret = false; 869 870 if ((__cap_grew(effective, ambient, new) && 871 !(__cap_full(effective, new) && 872 (__is_eff(root, new) || __is_real(root, new)) && 873 root_privileged())) || 874 (root_privileged() && 875 __is_suid(root, new) && 876 !__cap_full(effective, new)) || 877 (!__is_setuid(new, old) && 878 ((has_fcap && 879 __cap_gained(permitted, new, old)) || 880 __cap_gained(ambient, new, old)))) 881 882 ret = true; 883 884 return ret; 885 } 886 887 /** 888 * cap_bprm_creds_from_file - Set up the proposed credentials for execve(). 889 * @bprm: The execution parameters, including the proposed creds 890 * @file: The file to pull the credentials from 891 * 892 * Set up the proposed credentials for a new execution context being 893 * constructed by execve(). The proposed creds in @bprm->cred is altered, 894 * which won't take effect immediately. Returns 0 if successful, -ve on error. 895 */ 896 int cap_bprm_creds_from_file(struct linux_binprm *bprm, struct file *file) 897 { 898 /* Process setpcap binaries and capabilities for uid 0 */ 899 const struct cred *old = current_cred(); 900 struct cred *new = bprm->cred; 901 bool effective = false, has_fcap = false, is_setid; 902 int ret; 903 kuid_t root_uid; 904 905 if (WARN_ON(!cap_ambient_invariant_ok(old))) 906 return -EPERM; 907 908 ret = get_file_caps(bprm, file, &effective, &has_fcap); 909 if (ret < 0) 910 return ret; 911 912 root_uid = make_kuid(new->user_ns, 0); 913 914 handle_privileged_root(bprm, has_fcap, &effective, root_uid); 915 916 /* if we have fs caps, clear dangerous personality flags */ 917 if (__cap_gained(permitted, new, old)) 918 bprm->per_clear |= PER_CLEAR_ON_SETID; 919 920 /* Don't let someone trace a set[ug]id/setpcap binary with the revised 921 * credentials unless they have the appropriate permit. 922 * 923 * In addition, if NO_NEW_PRIVS, then ensure we get no new privs. 924 */ 925 is_setid = __is_setuid(new, old) || __is_setgid(new, old); 926 927 if ((is_setid || __cap_gained(permitted, new, old)) && 928 ((bprm->unsafe & ~LSM_UNSAFE_PTRACE) || 929 !ptracer_capable(current, new->user_ns))) { 930 /* downgrade; they get no more than they had, and maybe less */ 931 if (!ns_capable(new->user_ns, CAP_SETUID) || 932 (bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS)) { 933 new->euid = new->uid; 934 new->egid = new->gid; 935 } 936 new->cap_permitted = cap_intersect(new->cap_permitted, 937 old->cap_permitted); 938 } 939 940 new->suid = new->fsuid = new->euid; 941 new->sgid = new->fsgid = new->egid; 942 943 /* File caps or setid cancels ambient. */ 944 if (has_fcap || is_setid) 945 cap_clear(new->cap_ambient); 946 947 /* 948 * Now that we've computed pA', update pP' to give: 949 * pP' = (X & fP) | (pI & fI) | pA' 950 */ 951 new->cap_permitted = cap_combine(new->cap_permitted, new->cap_ambient); 952 953 /* 954 * Set pE' = (fE ? pP' : pA'). Because pA' is zero if fE is set, 955 * this is the same as pE' = (fE ? pP' : 0) | pA'. 956 */ 957 if (effective) 958 new->cap_effective = new->cap_permitted; 959 else 960 new->cap_effective = new->cap_ambient; 961 962 if (WARN_ON(!cap_ambient_invariant_ok(new))) 963 return -EPERM; 964 965 if (nonroot_raised_pE(new, old, root_uid, has_fcap)) { 966 ret = audit_log_bprm_fcaps(bprm, new, old); 967 if (ret < 0) 968 return ret; 969 } 970 971 new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS); 972 973 if (WARN_ON(!cap_ambient_invariant_ok(new))) 974 return -EPERM; 975 976 /* Check for privilege-elevated exec. */ 977 if (is_setid || 978 (!__is_real(root_uid, new) && 979 (effective || 980 __cap_grew(permitted, ambient, new)))) 981 bprm->secureexec = 1; 982 983 return 0; 984 } 985 986 /** 987 * cap_inode_setxattr - Determine whether an xattr may be altered 988 * @dentry: The inode/dentry being altered 989 * @name: The name of the xattr to be changed 990 * @value: The value that the xattr will be changed to 991 * @size: The size of value 992 * @flags: The replacement flag 993 * 994 * Determine whether an xattr may be altered or set on an inode, returning 0 if 995 * permission is granted, -ve if denied. 996 * 997 * This is used to make sure security xattrs don't get updated or set by those 998 * who aren't privileged to do so. 999 */ 1000 int cap_inode_setxattr(struct dentry *dentry, const char *name, 1001 const void *value, size_t size, int flags) 1002 { 1003 struct user_namespace *user_ns = dentry->d_sb->s_user_ns; 1004 1005 /* Ignore non-security xattrs */ 1006 if (strncmp(name, XATTR_SECURITY_PREFIX, 1007 XATTR_SECURITY_PREFIX_LEN) != 0) 1008 return 0; 1009 1010 /* 1011 * For XATTR_NAME_CAPS the check will be done in 1012 * cap_convert_nscap(), called by setxattr() 1013 */ 1014 if (strcmp(name, XATTR_NAME_CAPS) == 0) 1015 return 0; 1016 1017 if (!ns_capable(user_ns, CAP_SYS_ADMIN)) 1018 return -EPERM; 1019 return 0; 1020 } 1021 1022 /** 1023 * cap_inode_removexattr - Determine whether an xattr may be removed 1024 * 1025 * @mnt_userns: User namespace of the mount the inode was found from 1026 * @dentry: The inode/dentry being altered 1027 * @name: The name of the xattr to be changed 1028 * 1029 * Determine whether an xattr may be removed from an inode, returning 0 if 1030 * permission is granted, -ve if denied. 1031 * 1032 * If the inode has been found through an idmapped mount the user namespace of 1033 * the vfsmount must be passed through @mnt_userns. This function will then 1034 * take care to map the inode according to @mnt_userns before checking 1035 * permissions. On non-idmapped mounts or if permission checking is to be 1036 * performed on the raw inode simply passs init_user_ns. 1037 * 1038 * This is used to make sure security xattrs don't get removed by those who 1039 * aren't privileged to remove them. 1040 */ 1041 int cap_inode_removexattr(struct user_namespace *mnt_userns, 1042 struct dentry *dentry, const char *name) 1043 { 1044 struct user_namespace *user_ns = dentry->d_sb->s_user_ns; 1045 1046 /* Ignore non-security xattrs */ 1047 if (strncmp(name, XATTR_SECURITY_PREFIX, 1048 XATTR_SECURITY_PREFIX_LEN) != 0) 1049 return 0; 1050 1051 if (strcmp(name, XATTR_NAME_CAPS) == 0) { 1052 /* security.capability gets namespaced */ 1053 struct inode *inode = d_backing_inode(dentry); 1054 if (!inode) 1055 return -EINVAL; 1056 if (!capable_wrt_inode_uidgid(mnt_userns, inode, CAP_SETFCAP)) 1057 return -EPERM; 1058 return 0; 1059 } 1060 1061 if (!ns_capable(user_ns, CAP_SYS_ADMIN)) 1062 return -EPERM; 1063 return 0; 1064 } 1065 1066 /* 1067 * cap_emulate_setxuid() fixes the effective / permitted capabilities of 1068 * a process after a call to setuid, setreuid, or setresuid. 1069 * 1070 * 1) When set*uiding _from_ one of {r,e,s}uid == 0 _to_ all of 1071 * {r,e,s}uid != 0, the permitted and effective capabilities are 1072 * cleared. 1073 * 1074 * 2) When set*uiding _from_ euid == 0 _to_ euid != 0, the effective 1075 * capabilities of the process are cleared. 1076 * 1077 * 3) When set*uiding _from_ euid != 0 _to_ euid == 0, the effective 1078 * capabilities are set to the permitted capabilities. 1079 * 1080 * fsuid is handled elsewhere. fsuid == 0 and {r,e,s}uid!= 0 should 1081 * never happen. 1082 * 1083 * -astor 1084 * 1085 * cevans - New behaviour, Oct '99 1086 * A process may, via prctl(), elect to keep its capabilities when it 1087 * calls setuid() and switches away from uid==0. Both permitted and 1088 * effective sets will be retained. 1089 * Without this change, it was impossible for a daemon to drop only some 1090 * of its privilege. The call to setuid(!=0) would drop all privileges! 1091 * Keeping uid 0 is not an option because uid 0 owns too many vital 1092 * files.. 1093 * Thanks to Olaf Kirch and Peter Benie for spotting this. 1094 */ 1095 static inline void cap_emulate_setxuid(struct cred *new, const struct cred *old) 1096 { 1097 kuid_t root_uid = make_kuid(old->user_ns, 0); 1098 1099 if ((uid_eq(old->uid, root_uid) || 1100 uid_eq(old->euid, root_uid) || 1101 uid_eq(old->suid, root_uid)) && 1102 (!uid_eq(new->uid, root_uid) && 1103 !uid_eq(new->euid, root_uid) && 1104 !uid_eq(new->suid, root_uid))) { 1105 if (!issecure(SECURE_KEEP_CAPS)) { 1106 cap_clear(new->cap_permitted); 1107 cap_clear(new->cap_effective); 1108 } 1109 1110 /* 1111 * Pre-ambient programs expect setresuid to nonroot followed 1112 * by exec to drop capabilities. We should make sure that 1113 * this remains the case. 1114 */ 1115 cap_clear(new->cap_ambient); 1116 } 1117 if (uid_eq(old->euid, root_uid) && !uid_eq(new->euid, root_uid)) 1118 cap_clear(new->cap_effective); 1119 if (!uid_eq(old->euid, root_uid) && uid_eq(new->euid, root_uid)) 1120 new->cap_effective = new->cap_permitted; 1121 } 1122 1123 /** 1124 * cap_task_fix_setuid - Fix up the results of setuid() call 1125 * @new: The proposed credentials 1126 * @old: The current task's current credentials 1127 * @flags: Indications of what has changed 1128 * 1129 * Fix up the results of setuid() call before the credential changes are 1130 * actually applied, returning 0 to grant the changes, -ve to deny them. 1131 */ 1132 int cap_task_fix_setuid(struct cred *new, const struct cred *old, int flags) 1133 { 1134 switch (flags) { 1135 case LSM_SETID_RE: 1136 case LSM_SETID_ID: 1137 case LSM_SETID_RES: 1138 /* juggle the capabilities to follow [RES]UID changes unless 1139 * otherwise suppressed */ 1140 if (!issecure(SECURE_NO_SETUID_FIXUP)) 1141 cap_emulate_setxuid(new, old); 1142 break; 1143 1144 case LSM_SETID_FS: 1145 /* juggle the capabilties to follow FSUID changes, unless 1146 * otherwise suppressed 1147 * 1148 * FIXME - is fsuser used for all CAP_FS_MASK capabilities? 1149 * if not, we might be a bit too harsh here. 1150 */ 1151 if (!issecure(SECURE_NO_SETUID_FIXUP)) { 1152 kuid_t root_uid = make_kuid(old->user_ns, 0); 1153 if (uid_eq(old->fsuid, root_uid) && !uid_eq(new->fsuid, root_uid)) 1154 new->cap_effective = 1155 cap_drop_fs_set(new->cap_effective); 1156 1157 if (!uid_eq(old->fsuid, root_uid) && uid_eq(new->fsuid, root_uid)) 1158 new->cap_effective = 1159 cap_raise_fs_set(new->cap_effective, 1160 new->cap_permitted); 1161 } 1162 break; 1163 1164 default: 1165 return -EINVAL; 1166 } 1167 1168 return 0; 1169 } 1170 1171 /* 1172 * Rationale: code calling task_setscheduler, task_setioprio, and 1173 * task_setnice, assumes that 1174 * . if capable(cap_sys_nice), then those actions should be allowed 1175 * . if not capable(cap_sys_nice), but acting on your own processes, 1176 * then those actions should be allowed 1177 * This is insufficient now since you can call code without suid, but 1178 * yet with increased caps. 1179 * So we check for increased caps on the target process. 1180 */ 1181 static int cap_safe_nice(struct task_struct *p) 1182 { 1183 int is_subset, ret = 0; 1184 1185 rcu_read_lock(); 1186 is_subset = cap_issubset(__task_cred(p)->cap_permitted, 1187 current_cred()->cap_permitted); 1188 if (!is_subset && !ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) 1189 ret = -EPERM; 1190 rcu_read_unlock(); 1191 1192 return ret; 1193 } 1194 1195 /** 1196 * cap_task_setscheduler - Detemine if scheduler policy change is permitted 1197 * @p: The task to affect 1198 * 1199 * Detemine if the requested scheduler policy change is permitted for the 1200 * specified task, returning 0 if permission is granted, -ve if denied. 1201 */ 1202 int cap_task_setscheduler(struct task_struct *p) 1203 { 1204 return cap_safe_nice(p); 1205 } 1206 1207 /** 1208 * cap_task_ioprio - Detemine if I/O priority change is permitted 1209 * @p: The task to affect 1210 * @ioprio: The I/O priority to set 1211 * 1212 * Detemine if the requested I/O priority change is permitted for the specified 1213 * task, returning 0 if permission is granted, -ve if denied. 1214 */ 1215 int cap_task_setioprio(struct task_struct *p, int ioprio) 1216 { 1217 return cap_safe_nice(p); 1218 } 1219 1220 /** 1221 * cap_task_ioprio - Detemine if task priority change is permitted 1222 * @p: The task to affect 1223 * @nice: The nice value to set 1224 * 1225 * Detemine if the requested task priority change is permitted for the 1226 * specified task, returning 0 if permission is granted, -ve if denied. 1227 */ 1228 int cap_task_setnice(struct task_struct *p, int nice) 1229 { 1230 return cap_safe_nice(p); 1231 } 1232 1233 /* 1234 * Implement PR_CAPBSET_DROP. Attempt to remove the specified capability from 1235 * the current task's bounding set. Returns 0 on success, -ve on error. 1236 */ 1237 static int cap_prctl_drop(unsigned long cap) 1238 { 1239 struct cred *new; 1240 1241 if (!ns_capable(current_user_ns(), CAP_SETPCAP)) 1242 return -EPERM; 1243 if (!cap_valid(cap)) 1244 return -EINVAL; 1245 1246 new = prepare_creds(); 1247 if (!new) 1248 return -ENOMEM; 1249 cap_lower(new->cap_bset, cap); 1250 return commit_creds(new); 1251 } 1252 1253 /** 1254 * cap_task_prctl - Implement process control functions for this security module 1255 * @option: The process control function requested 1256 * @arg2, @arg3, @arg4, @arg5: The argument data for this function 1257 * 1258 * Allow process control functions (sys_prctl()) to alter capabilities; may 1259 * also deny access to other functions not otherwise implemented here. 1260 * 1261 * Returns 0 or +ve on success, -ENOSYS if this function is not implemented 1262 * here, other -ve on error. If -ENOSYS is returned, sys_prctl() and other LSM 1263 * modules will consider performing the function. 1264 */ 1265 int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3, 1266 unsigned long arg4, unsigned long arg5) 1267 { 1268 const struct cred *old = current_cred(); 1269 struct cred *new; 1270 1271 switch (option) { 1272 case PR_CAPBSET_READ: 1273 if (!cap_valid(arg2)) 1274 return -EINVAL; 1275 return !!cap_raised(old->cap_bset, arg2); 1276 1277 case PR_CAPBSET_DROP: 1278 return cap_prctl_drop(arg2); 1279 1280 /* 1281 * The next four prctl's remain to assist with transitioning a 1282 * system from legacy UID=0 based privilege (when filesystem 1283 * capabilities are not in use) to a system using filesystem 1284 * capabilities only - as the POSIX.1e draft intended. 1285 * 1286 * Note: 1287 * 1288 * PR_SET_SECUREBITS = 1289 * issecure_mask(SECURE_KEEP_CAPS_LOCKED) 1290 * | issecure_mask(SECURE_NOROOT) 1291 * | issecure_mask(SECURE_NOROOT_LOCKED) 1292 * | issecure_mask(SECURE_NO_SETUID_FIXUP) 1293 * | issecure_mask(SECURE_NO_SETUID_FIXUP_LOCKED) 1294 * 1295 * will ensure that the current process and all of its 1296 * children will be locked into a pure 1297 * capability-based-privilege environment. 1298 */ 1299 case PR_SET_SECUREBITS: 1300 if ((((old->securebits & SECURE_ALL_LOCKS) >> 1) 1301 & (old->securebits ^ arg2)) /*[1]*/ 1302 || ((old->securebits & SECURE_ALL_LOCKS & ~arg2)) /*[2]*/ 1303 || (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS)) /*[3]*/ 1304 || (cap_capable(current_cred(), 1305 current_cred()->user_ns, 1306 CAP_SETPCAP, 1307 CAP_OPT_NONE) != 0) /*[4]*/ 1308 /* 1309 * [1] no changing of bits that are locked 1310 * [2] no unlocking of locks 1311 * [3] no setting of unsupported bits 1312 * [4] doing anything requires privilege (go read about 1313 * the "sendmail capabilities bug") 1314 */ 1315 ) 1316 /* cannot change a locked bit */ 1317 return -EPERM; 1318 1319 new = prepare_creds(); 1320 if (!new) 1321 return -ENOMEM; 1322 new->securebits = arg2; 1323 return commit_creds(new); 1324 1325 case PR_GET_SECUREBITS: 1326 return old->securebits; 1327 1328 case PR_GET_KEEPCAPS: 1329 return !!issecure(SECURE_KEEP_CAPS); 1330 1331 case PR_SET_KEEPCAPS: 1332 if (arg2 > 1) /* Note, we rely on arg2 being unsigned here */ 1333 return -EINVAL; 1334 if (issecure(SECURE_KEEP_CAPS_LOCKED)) 1335 return -EPERM; 1336 1337 new = prepare_creds(); 1338 if (!new) 1339 return -ENOMEM; 1340 if (arg2) 1341 new->securebits |= issecure_mask(SECURE_KEEP_CAPS); 1342 else 1343 new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS); 1344 return commit_creds(new); 1345 1346 case PR_CAP_AMBIENT: 1347 if (arg2 == PR_CAP_AMBIENT_CLEAR_ALL) { 1348 if (arg3 | arg4 | arg5) 1349 return -EINVAL; 1350 1351 new = prepare_creds(); 1352 if (!new) 1353 return -ENOMEM; 1354 cap_clear(new->cap_ambient); 1355 return commit_creds(new); 1356 } 1357 1358 if (((!cap_valid(arg3)) | arg4 | arg5)) 1359 return -EINVAL; 1360 1361 if (arg2 == PR_CAP_AMBIENT_IS_SET) { 1362 return !!cap_raised(current_cred()->cap_ambient, arg3); 1363 } else if (arg2 != PR_CAP_AMBIENT_RAISE && 1364 arg2 != PR_CAP_AMBIENT_LOWER) { 1365 return -EINVAL; 1366 } else { 1367 if (arg2 == PR_CAP_AMBIENT_RAISE && 1368 (!cap_raised(current_cred()->cap_permitted, arg3) || 1369 !cap_raised(current_cred()->cap_inheritable, 1370 arg3) || 1371 issecure(SECURE_NO_CAP_AMBIENT_RAISE))) 1372 return -EPERM; 1373 1374 new = prepare_creds(); 1375 if (!new) 1376 return -ENOMEM; 1377 if (arg2 == PR_CAP_AMBIENT_RAISE) 1378 cap_raise(new->cap_ambient, arg3); 1379 else 1380 cap_lower(new->cap_ambient, arg3); 1381 return commit_creds(new); 1382 } 1383 1384 default: 1385 /* No functionality available - continue with default */ 1386 return -ENOSYS; 1387 } 1388 } 1389 1390 /** 1391 * cap_vm_enough_memory - Determine whether a new virtual mapping is permitted 1392 * @mm: The VM space in which the new mapping is to be made 1393 * @pages: The size of the mapping 1394 * 1395 * Determine whether the allocation of a new virtual mapping by the current 1396 * task is permitted, returning 1 if permission is granted, 0 if not. 1397 */ 1398 int cap_vm_enough_memory(struct mm_struct *mm, long pages) 1399 { 1400 int cap_sys_admin = 0; 1401 1402 if (cap_capable(current_cred(), &init_user_ns, 1403 CAP_SYS_ADMIN, CAP_OPT_NOAUDIT) == 0) 1404 cap_sys_admin = 1; 1405 1406 return cap_sys_admin; 1407 } 1408 1409 /* 1410 * cap_mmap_addr - check if able to map given addr 1411 * @addr: address attempting to be mapped 1412 * 1413 * If the process is attempting to map memory below dac_mmap_min_addr they need 1414 * CAP_SYS_RAWIO. The other parameters to this function are unused by the 1415 * capability security module. Returns 0 if this mapping should be allowed 1416 * -EPERM if not. 1417 */ 1418 int cap_mmap_addr(unsigned long addr) 1419 { 1420 int ret = 0; 1421 1422 if (addr < dac_mmap_min_addr) { 1423 ret = cap_capable(current_cred(), &init_user_ns, CAP_SYS_RAWIO, 1424 CAP_OPT_NONE); 1425 /* set PF_SUPERPRIV if it turns out we allow the low mmap */ 1426 if (ret == 0) 1427 current->flags |= PF_SUPERPRIV; 1428 } 1429 return ret; 1430 } 1431 1432 int cap_mmap_file(struct file *file, unsigned long reqprot, 1433 unsigned long prot, unsigned long flags) 1434 { 1435 return 0; 1436 } 1437 1438 #ifdef CONFIG_SECURITY 1439 1440 static struct security_hook_list capability_hooks[] __lsm_ro_after_init = { 1441 LSM_HOOK_INIT(capable, cap_capable), 1442 LSM_HOOK_INIT(settime, cap_settime), 1443 LSM_HOOK_INIT(ptrace_access_check, cap_ptrace_access_check), 1444 LSM_HOOK_INIT(ptrace_traceme, cap_ptrace_traceme), 1445 LSM_HOOK_INIT(capget, cap_capget), 1446 LSM_HOOK_INIT(capset, cap_capset), 1447 LSM_HOOK_INIT(bprm_creds_from_file, cap_bprm_creds_from_file), 1448 LSM_HOOK_INIT(inode_need_killpriv, cap_inode_need_killpriv), 1449 LSM_HOOK_INIT(inode_killpriv, cap_inode_killpriv), 1450 LSM_HOOK_INIT(inode_getsecurity, cap_inode_getsecurity), 1451 LSM_HOOK_INIT(mmap_addr, cap_mmap_addr), 1452 LSM_HOOK_INIT(mmap_file, cap_mmap_file), 1453 LSM_HOOK_INIT(task_fix_setuid, cap_task_fix_setuid), 1454 LSM_HOOK_INIT(task_prctl, cap_task_prctl), 1455 LSM_HOOK_INIT(task_setscheduler, cap_task_setscheduler), 1456 LSM_HOOK_INIT(task_setioprio, cap_task_setioprio), 1457 LSM_HOOK_INIT(task_setnice, cap_task_setnice), 1458 LSM_HOOK_INIT(vm_enough_memory, cap_vm_enough_memory), 1459 }; 1460 1461 static int __init capability_init(void) 1462 { 1463 security_add_hooks(capability_hooks, ARRAY_SIZE(capability_hooks), 1464 "capability"); 1465 return 0; 1466 } 1467 1468 DEFINE_LSM(capability) = { 1469 .name = "capability", 1470 .order = LSM_ORDER_FIRST, 1471 .init = capability_init, 1472 }; 1473 1474 #endif /* CONFIG_SECURITY */ 1475