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 #include <linux/mnt_idmapping.h> 28 29 /* 30 * If a non-root user executes a setuid-root binary in 31 * !secure(SECURE_NOROOT) mode, then we raise capabilities. 32 * However if fE is also set, then the intent is for only 33 * the file capabilities to be applied, and the setuid-root 34 * bit is left on either to change the uid (plausible) or 35 * to get full privilege on a kernel without file capabilities 36 * support. So in that case we do not raise capabilities. 37 * 38 * Warn if that happens, once per boot. 39 */ 40 static void warn_setuid_and_fcaps_mixed(const char *fname) 41 { 42 static int warned; 43 if (!warned) { 44 printk(KERN_INFO "warning: `%s' has both setuid-root and" 45 " effective capabilities. Therefore not raising all" 46 " capabilities.\n", fname); 47 warned = 1; 48 } 49 } 50 51 /** 52 * cap_capable - Determine whether a task has a particular effective capability 53 * @cred: The credentials to use 54 * @targ_ns: The user namespace in which we need the capability 55 * @cap: The capability to check for 56 * @opts: Bitmask of options defined in include/linux/security.h 57 * 58 * Determine whether the nominated task has the specified capability amongst 59 * its effective set, returning 0 if it does, -ve if it does not. 60 * 61 * NOTE WELL: cap_has_capability() cannot be used like the kernel's capable() 62 * and has_capability() functions. That is, it has the reverse semantics: 63 * cap_has_capability() returns 0 when a task has a capability, but the 64 * kernel's capable() and has_capability() returns 1 for this case. 65 */ 66 int cap_capable(const struct cred *cred, struct user_namespace *targ_ns, 67 int cap, unsigned int opts) 68 { 69 struct user_namespace *ns = targ_ns; 70 71 /* See if cred has the capability in the target user namespace 72 * by examining the target user namespace and all of the target 73 * user namespace's parents. 74 */ 75 for (;;) { 76 /* Do we have the necessary capabilities? */ 77 if (ns == cred->user_ns) 78 return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM; 79 80 /* 81 * If we're already at a lower level than we're looking for, 82 * we're done searching. 83 */ 84 if (ns->level <= cred->user_ns->level) 85 return -EPERM; 86 87 /* 88 * The owner of the user namespace in the parent of the 89 * user namespace has all caps. 90 */ 91 if ((ns->parent == cred->user_ns) && uid_eq(ns->owner, cred->euid)) 92 return 0; 93 94 /* 95 * If you have a capability in a parent user ns, then you have 96 * it over all children user namespaces as well. 97 */ 98 ns = ns->parent; 99 } 100 101 /* We never get here */ 102 } 103 104 /** 105 * cap_settime - Determine whether the current process may set the system clock 106 * @ts: The time to set 107 * @tz: The timezone to set 108 * 109 * Determine whether the current process may set the system clock and timezone 110 * information, returning 0 if permission granted, -ve if denied. 111 */ 112 int cap_settime(const struct timespec64 *ts, const struct timezone *tz) 113 { 114 if (!capable(CAP_SYS_TIME)) 115 return -EPERM; 116 return 0; 117 } 118 119 /** 120 * cap_ptrace_access_check - Determine whether the current process may access 121 * another 122 * @child: The process to be accessed 123 * @mode: The mode of attachment. 124 * 125 * If we are in the same or an ancestor user_ns and have all the target 126 * task's capabilities, then ptrace access is allowed. 127 * If we have the ptrace capability to the target user_ns, then ptrace 128 * access is allowed. 129 * Else denied. 130 * 131 * Determine whether a process may access another, returning 0 if permission 132 * granted, -ve if denied. 133 */ 134 int cap_ptrace_access_check(struct task_struct *child, unsigned int mode) 135 { 136 int ret = 0; 137 const struct cred *cred, *child_cred; 138 const kernel_cap_t *caller_caps; 139 140 rcu_read_lock(); 141 cred = current_cred(); 142 child_cred = __task_cred(child); 143 if (mode & PTRACE_MODE_FSCREDS) 144 caller_caps = &cred->cap_effective; 145 else 146 caller_caps = &cred->cap_permitted; 147 if (cred->user_ns == child_cred->user_ns && 148 cap_issubset(child_cred->cap_permitted, *caller_caps)) 149 goto out; 150 if (ns_capable(child_cred->user_ns, CAP_SYS_PTRACE)) 151 goto out; 152 ret = -EPERM; 153 out: 154 rcu_read_unlock(); 155 return ret; 156 } 157 158 /** 159 * cap_ptrace_traceme - Determine whether another process may trace the current 160 * @parent: The task proposed to be the tracer 161 * 162 * If parent is in the same or an ancestor user_ns and has all current's 163 * capabilities, then ptrace access is allowed. 164 * If parent has the ptrace capability to current's user_ns, then ptrace 165 * access is allowed. 166 * Else denied. 167 * 168 * Determine whether the nominated task is permitted to trace the current 169 * process, returning 0 if permission is granted, -ve if denied. 170 */ 171 int cap_ptrace_traceme(struct task_struct *parent) 172 { 173 int ret = 0; 174 const struct cred *cred, *child_cred; 175 176 rcu_read_lock(); 177 cred = __task_cred(parent); 178 child_cred = current_cred(); 179 if (cred->user_ns == child_cred->user_ns && 180 cap_issubset(child_cred->cap_permitted, cred->cap_permitted)) 181 goto out; 182 if (has_ns_capability(parent, child_cred->user_ns, CAP_SYS_PTRACE)) 183 goto out; 184 ret = -EPERM; 185 out: 186 rcu_read_unlock(); 187 return ret; 188 } 189 190 /** 191 * cap_capget - Retrieve a task's capability sets 192 * @target: The task from which to retrieve the capability sets 193 * @effective: The place to record the effective set 194 * @inheritable: The place to record the inheritable set 195 * @permitted: The place to record the permitted set 196 * 197 * This function retrieves the capabilities of the nominated task and returns 198 * them to the caller. 199 */ 200 int cap_capget(struct task_struct *target, kernel_cap_t *effective, 201 kernel_cap_t *inheritable, kernel_cap_t *permitted) 202 { 203 const struct cred *cred; 204 205 /* Derived from kernel/capability.c:sys_capget. */ 206 rcu_read_lock(); 207 cred = __task_cred(target); 208 *effective = cred->cap_effective; 209 *inheritable = cred->cap_inheritable; 210 *permitted = cred->cap_permitted; 211 rcu_read_unlock(); 212 return 0; 213 } 214 215 /* 216 * Determine whether the inheritable capabilities are limited to the old 217 * permitted set. Returns 1 if they are limited, 0 if they are not. 218 */ 219 static inline int cap_inh_is_capped(void) 220 { 221 /* they are so limited unless the current task has the CAP_SETPCAP 222 * capability 223 */ 224 if (cap_capable(current_cred(), current_cred()->user_ns, 225 CAP_SETPCAP, CAP_OPT_NONE) == 0) 226 return 0; 227 return 1; 228 } 229 230 /** 231 * cap_capset - Validate and apply proposed changes to current's capabilities 232 * @new: The proposed new credentials; alterations should be made here 233 * @old: The current task's current credentials 234 * @effective: A pointer to the proposed new effective capabilities set 235 * @inheritable: A pointer to the proposed new inheritable capabilities set 236 * @permitted: A pointer to the proposed new permitted capabilities set 237 * 238 * This function validates and applies a proposed mass change to the current 239 * process's capability sets. The changes are made to the proposed new 240 * credentials, and assuming no error, will be committed by the caller of LSM. 241 */ 242 int cap_capset(struct cred *new, 243 const struct cred *old, 244 const kernel_cap_t *effective, 245 const kernel_cap_t *inheritable, 246 const kernel_cap_t *permitted) 247 { 248 if (cap_inh_is_capped() && 249 !cap_issubset(*inheritable, 250 cap_combine(old->cap_inheritable, 251 old->cap_permitted))) 252 /* incapable of using this inheritable set */ 253 return -EPERM; 254 255 if (!cap_issubset(*inheritable, 256 cap_combine(old->cap_inheritable, 257 old->cap_bset))) 258 /* no new pI capabilities outside bounding set */ 259 return -EPERM; 260 261 /* verify restrictions on target's new Permitted set */ 262 if (!cap_issubset(*permitted, old->cap_permitted)) 263 return -EPERM; 264 265 /* verify the _new_Effective_ is a subset of the _new_Permitted_ */ 266 if (!cap_issubset(*effective, *permitted)) 267 return -EPERM; 268 269 new->cap_effective = *effective; 270 new->cap_inheritable = *inheritable; 271 new->cap_permitted = *permitted; 272 273 /* 274 * Mask off ambient bits that are no longer both permitted and 275 * inheritable. 276 */ 277 new->cap_ambient = cap_intersect(new->cap_ambient, 278 cap_intersect(*permitted, 279 *inheritable)); 280 if (WARN_ON(!cap_ambient_invariant_ok(new))) 281 return -EINVAL; 282 return 0; 283 } 284 285 /** 286 * cap_inode_need_killpriv - Determine if inode change affects privileges 287 * @dentry: The inode/dentry in being changed with change marked ATTR_KILL_PRIV 288 * 289 * Determine if an inode having a change applied that's marked ATTR_KILL_PRIV 290 * affects the security markings on that inode, and if it is, should 291 * inode_killpriv() be invoked or the change rejected. 292 * 293 * Return: 1 if security.capability has a value, meaning inode_killpriv() 294 * is required, 0 otherwise, meaning inode_killpriv() is not required. 295 */ 296 int cap_inode_need_killpriv(struct dentry *dentry) 297 { 298 struct inode *inode = d_backing_inode(dentry); 299 int error; 300 301 error = __vfs_getxattr(dentry, inode, XATTR_NAME_CAPS, NULL, 0); 302 return error > 0; 303 } 304 305 /** 306 * cap_inode_killpriv - Erase the security markings on an inode 307 * 308 * @mnt_userns: user namespace of the mount the inode was found from 309 * @dentry: The inode/dentry to alter 310 * 311 * Erase the privilege-enhancing security markings on an inode. 312 * 313 * If the inode has been found through an idmapped mount the user namespace of 314 * the vfsmount must be passed through @mnt_userns. This function will then 315 * take care to map the inode according to @mnt_userns before checking 316 * permissions. On non-idmapped mounts or if permission checking is to be 317 * performed on the raw inode simply passs init_user_ns. 318 * 319 * Return: 0 if successful, -ve on error. 320 */ 321 int cap_inode_killpriv(struct user_namespace *mnt_userns, struct dentry *dentry) 322 { 323 int error; 324 325 error = __vfs_removexattr(mnt_userns, dentry, XATTR_NAME_CAPS); 326 if (error == -EOPNOTSUPP) 327 error = 0; 328 return error; 329 } 330 331 static bool rootid_owns_currentns(kuid_t kroot) 332 { 333 struct user_namespace *ns; 334 335 if (!uid_valid(kroot)) 336 return false; 337 338 for (ns = current_user_ns(); ; ns = ns->parent) { 339 if (from_kuid(ns, kroot) == 0) 340 return true; 341 if (ns == &init_user_ns) 342 break; 343 } 344 345 return false; 346 } 347 348 static __u32 sansflags(__u32 m) 349 { 350 return m & ~VFS_CAP_FLAGS_EFFECTIVE; 351 } 352 353 static bool is_v2header(size_t size, const struct vfs_cap_data *cap) 354 { 355 if (size != XATTR_CAPS_SZ_2) 356 return false; 357 return sansflags(le32_to_cpu(cap->magic_etc)) == VFS_CAP_REVISION_2; 358 } 359 360 static bool is_v3header(size_t size, const struct vfs_cap_data *cap) 361 { 362 if (size != XATTR_CAPS_SZ_3) 363 return false; 364 return sansflags(le32_to_cpu(cap->magic_etc)) == VFS_CAP_REVISION_3; 365 } 366 367 /* 368 * getsecurity: We are called for security.* before any attempt to read the 369 * xattr from the inode itself. 370 * 371 * This gives us a chance to read the on-disk value and convert it. If we 372 * return -EOPNOTSUPP, then vfs_getxattr() will call the i_op handler. 373 * 374 * Note we are not called by vfs_getxattr_alloc(), but that is only called 375 * by the integrity subsystem, which really wants the unconverted values - 376 * so that's good. 377 */ 378 int cap_inode_getsecurity(struct user_namespace *mnt_userns, 379 struct inode *inode, const char *name, void **buffer, 380 bool alloc) 381 { 382 int size, ret; 383 kuid_t kroot; 384 u32 nsmagic, magic; 385 uid_t root, mappedroot; 386 char *tmpbuf = NULL; 387 struct vfs_cap_data *cap; 388 struct vfs_ns_cap_data *nscap = NULL; 389 struct dentry *dentry; 390 struct user_namespace *fs_ns; 391 392 if (strcmp(name, "capability") != 0) 393 return -EOPNOTSUPP; 394 395 dentry = d_find_any_alias(inode); 396 if (!dentry) 397 return -EINVAL; 398 399 size = sizeof(struct vfs_ns_cap_data); 400 ret = (int)vfs_getxattr_alloc(mnt_userns, dentry, XATTR_NAME_CAPS, 401 &tmpbuf, size, GFP_NOFS); 402 dput(dentry); 403 404 if (ret < 0 || !tmpbuf) 405 return ret; 406 407 fs_ns = inode->i_sb->s_user_ns; 408 cap = (struct vfs_cap_data *) tmpbuf; 409 if (is_v2header((size_t) ret, cap)) { 410 root = 0; 411 } else if (is_v3header((size_t) ret, cap)) { 412 nscap = (struct vfs_ns_cap_data *) tmpbuf; 413 root = le32_to_cpu(nscap->rootid); 414 } else { 415 size = -EINVAL; 416 goto out_free; 417 } 418 419 kroot = make_kuid(fs_ns, root); 420 421 /* If this is an idmapped mount shift the kuid. */ 422 kroot = mapped_kuid_fs(mnt_userns, fs_ns, kroot); 423 424 /* If the root kuid maps to a valid uid in current ns, then return 425 * this as a nscap. */ 426 mappedroot = from_kuid(current_user_ns(), kroot); 427 if (mappedroot != (uid_t)-1 && mappedroot != (uid_t)0) { 428 size = sizeof(struct vfs_ns_cap_data); 429 if (alloc) { 430 if (!nscap) { 431 /* v2 -> v3 conversion */ 432 nscap = kzalloc(size, GFP_ATOMIC); 433 if (!nscap) { 434 size = -ENOMEM; 435 goto out_free; 436 } 437 nsmagic = VFS_CAP_REVISION_3; 438 magic = le32_to_cpu(cap->magic_etc); 439 if (magic & VFS_CAP_FLAGS_EFFECTIVE) 440 nsmagic |= VFS_CAP_FLAGS_EFFECTIVE; 441 memcpy(&nscap->data, &cap->data, sizeof(__le32) * 2 * VFS_CAP_U32); 442 nscap->magic_etc = cpu_to_le32(nsmagic); 443 } else { 444 /* use allocated v3 buffer */ 445 tmpbuf = NULL; 446 } 447 nscap->rootid = cpu_to_le32(mappedroot); 448 *buffer = nscap; 449 } 450 goto out_free; 451 } 452 453 if (!rootid_owns_currentns(kroot)) { 454 size = -EOVERFLOW; 455 goto out_free; 456 } 457 458 /* This comes from a parent namespace. Return as a v2 capability */ 459 size = sizeof(struct vfs_cap_data); 460 if (alloc) { 461 if (nscap) { 462 /* v3 -> v2 conversion */ 463 cap = kzalloc(size, GFP_ATOMIC); 464 if (!cap) { 465 size = -ENOMEM; 466 goto out_free; 467 } 468 magic = VFS_CAP_REVISION_2; 469 nsmagic = le32_to_cpu(nscap->magic_etc); 470 if (nsmagic & VFS_CAP_FLAGS_EFFECTIVE) 471 magic |= VFS_CAP_FLAGS_EFFECTIVE; 472 memcpy(&cap->data, &nscap->data, sizeof(__le32) * 2 * VFS_CAP_U32); 473 cap->magic_etc = cpu_to_le32(magic); 474 } else { 475 /* use unconverted v2 */ 476 tmpbuf = NULL; 477 } 478 *buffer = cap; 479 } 480 out_free: 481 kfree(tmpbuf); 482 return size; 483 } 484 485 /** 486 * rootid_from_xattr - translate root uid of vfs caps 487 * 488 * @value: vfs caps value which may be modified by this function 489 * @size: size of @ivalue 490 * @task_ns: user namespace of the caller 491 * @mnt_userns: user namespace of the mount the inode was found from 492 * @fs_userns: user namespace of the filesystem 493 * 494 * If the inode has been found through an idmapped mount the user namespace of 495 * the vfsmount must be passed through @mnt_userns. This function will then 496 * take care to map the inode according to @mnt_userns before checking 497 * permissions. On non-idmapped mounts or if permission checking is to be 498 * performed on the raw inode simply passs init_user_ns. 499 */ 500 static kuid_t rootid_from_xattr(const void *value, size_t size, 501 struct user_namespace *task_ns, 502 struct user_namespace *mnt_userns, 503 struct user_namespace *fs_userns) 504 { 505 const struct vfs_ns_cap_data *nscap = value; 506 kuid_t rootkid; 507 uid_t rootid = 0; 508 509 if (size == XATTR_CAPS_SZ_3) 510 rootid = le32_to_cpu(nscap->rootid); 511 512 rootkid = make_kuid(task_ns, rootid); 513 return mapped_kuid_user(mnt_userns, fs_userns, rootkid); 514 } 515 516 static bool validheader(size_t size, const struct vfs_cap_data *cap) 517 { 518 return is_v2header(size, cap) || is_v3header(size, cap); 519 } 520 521 /** 522 * cap_convert_nscap - check vfs caps 523 * 524 * @mnt_userns: user namespace of the mount the inode was found from 525 * @dentry: used to retrieve inode to check permissions on 526 * @ivalue: vfs caps value which may be modified by this function 527 * @size: size of @ivalue 528 * 529 * User requested a write of security.capability. If needed, update the 530 * xattr to change from v2 to v3, or to fixup the v3 rootid. 531 * 532 * If the inode has been found through an idmapped mount the user namespace of 533 * the vfsmount must be passed through @mnt_userns. This function will then 534 * take care to map the inode according to @mnt_userns before checking 535 * permissions. On non-idmapped mounts or if permission checking is to be 536 * performed on the raw inode simply passs init_user_ns. 537 * 538 * Return: On success, return the new size; on error, return < 0. 539 */ 540 int cap_convert_nscap(struct user_namespace *mnt_userns, struct dentry *dentry, 541 const void **ivalue, size_t size) 542 { 543 struct vfs_ns_cap_data *nscap; 544 uid_t nsrootid; 545 const struct vfs_cap_data *cap = *ivalue; 546 __u32 magic, nsmagic; 547 struct inode *inode = d_backing_inode(dentry); 548 struct user_namespace *task_ns = current_user_ns(), 549 *fs_ns = inode->i_sb->s_user_ns; 550 kuid_t rootid; 551 size_t newsize; 552 553 if (!*ivalue) 554 return -EINVAL; 555 if (!validheader(size, cap)) 556 return -EINVAL; 557 if (!capable_wrt_inode_uidgid(mnt_userns, inode, CAP_SETFCAP)) 558 return -EPERM; 559 if (size == XATTR_CAPS_SZ_2 && (mnt_userns == fs_ns)) 560 if (ns_capable(inode->i_sb->s_user_ns, CAP_SETFCAP)) 561 /* user is privileged, just write the v2 */ 562 return size; 563 564 rootid = rootid_from_xattr(*ivalue, size, task_ns, mnt_userns, fs_ns); 565 if (!uid_valid(rootid)) 566 return -EINVAL; 567 568 nsrootid = from_kuid(fs_ns, rootid); 569 if (nsrootid == -1) 570 return -EINVAL; 571 572 newsize = sizeof(struct vfs_ns_cap_data); 573 nscap = kmalloc(newsize, GFP_ATOMIC); 574 if (!nscap) 575 return -ENOMEM; 576 nscap->rootid = cpu_to_le32(nsrootid); 577 nsmagic = VFS_CAP_REVISION_3; 578 magic = le32_to_cpu(cap->magic_etc); 579 if (magic & VFS_CAP_FLAGS_EFFECTIVE) 580 nsmagic |= VFS_CAP_FLAGS_EFFECTIVE; 581 nscap->magic_etc = cpu_to_le32(nsmagic); 582 memcpy(&nscap->data, &cap->data, sizeof(__le32) * 2 * VFS_CAP_U32); 583 584 *ivalue = nscap; 585 return newsize; 586 } 587 588 /* 589 * Calculate the new process capability sets from the capability sets attached 590 * to a file. 591 */ 592 static inline int bprm_caps_from_vfs_caps(struct cpu_vfs_cap_data *caps, 593 struct linux_binprm *bprm, 594 bool *effective, 595 bool *has_fcap) 596 { 597 struct cred *new = bprm->cred; 598 unsigned i; 599 int ret = 0; 600 601 if (caps->magic_etc & VFS_CAP_FLAGS_EFFECTIVE) 602 *effective = true; 603 604 if (caps->magic_etc & VFS_CAP_REVISION_MASK) 605 *has_fcap = true; 606 607 CAP_FOR_EACH_U32(i) { 608 __u32 permitted = caps->permitted.cap[i]; 609 __u32 inheritable = caps->inheritable.cap[i]; 610 611 /* 612 * pP' = (X & fP) | (pI & fI) 613 * The addition of pA' is handled later. 614 */ 615 new->cap_permitted.cap[i] = 616 (new->cap_bset.cap[i] & permitted) | 617 (new->cap_inheritable.cap[i] & inheritable); 618 619 if (permitted & ~new->cap_permitted.cap[i]) 620 /* insufficient to execute correctly */ 621 ret = -EPERM; 622 } 623 624 /* 625 * For legacy apps, with no internal support for recognizing they 626 * do not have enough capabilities, we return an error if they are 627 * missing some "forced" (aka file-permitted) capabilities. 628 */ 629 return *effective ? ret : 0; 630 } 631 632 /** 633 * get_vfs_caps_from_disk - retrieve vfs caps from disk 634 * 635 * @mnt_userns: user namespace of the mount the inode was found from 636 * @dentry: dentry from which @inode is retrieved 637 * @cpu_caps: vfs capabilities 638 * 639 * Extract the on-exec-apply capability sets for an executable file. 640 * 641 * If the inode has been found through an idmapped mount the user namespace of 642 * the vfsmount must be passed through @mnt_userns. This function will then 643 * take care to map the inode according to @mnt_userns before checking 644 * permissions. On non-idmapped mounts or if permission checking is to be 645 * performed on the raw inode simply passs init_user_ns. 646 */ 647 int get_vfs_caps_from_disk(struct user_namespace *mnt_userns, 648 const struct dentry *dentry, 649 struct cpu_vfs_cap_data *cpu_caps) 650 { 651 struct inode *inode = d_backing_inode(dentry); 652 __u32 magic_etc; 653 unsigned tocopy, i; 654 int size; 655 struct vfs_ns_cap_data data, *nscaps = &data; 656 struct vfs_cap_data *caps = (struct vfs_cap_data *) &data; 657 kuid_t rootkuid; 658 struct user_namespace *fs_ns; 659 660 memset(cpu_caps, 0, sizeof(struct cpu_vfs_cap_data)); 661 662 if (!inode) 663 return -ENODATA; 664 665 fs_ns = inode->i_sb->s_user_ns; 666 size = __vfs_getxattr((struct dentry *)dentry, inode, 667 XATTR_NAME_CAPS, &data, XATTR_CAPS_SZ); 668 if (size == -ENODATA || size == -EOPNOTSUPP) 669 /* no data, that's ok */ 670 return -ENODATA; 671 672 if (size < 0) 673 return size; 674 675 if (size < sizeof(magic_etc)) 676 return -EINVAL; 677 678 cpu_caps->magic_etc = magic_etc = le32_to_cpu(caps->magic_etc); 679 680 rootkuid = make_kuid(fs_ns, 0); 681 switch (magic_etc & VFS_CAP_REVISION_MASK) { 682 case VFS_CAP_REVISION_1: 683 if (size != XATTR_CAPS_SZ_1) 684 return -EINVAL; 685 tocopy = VFS_CAP_U32_1; 686 break; 687 case VFS_CAP_REVISION_2: 688 if (size != XATTR_CAPS_SZ_2) 689 return -EINVAL; 690 tocopy = VFS_CAP_U32_2; 691 break; 692 case VFS_CAP_REVISION_3: 693 if (size != XATTR_CAPS_SZ_3) 694 return -EINVAL; 695 tocopy = VFS_CAP_U32_3; 696 rootkuid = make_kuid(fs_ns, le32_to_cpu(nscaps->rootid)); 697 break; 698 699 default: 700 return -EINVAL; 701 } 702 /* Limit the caps to the mounter of the filesystem 703 * or the more limited uid specified in the xattr. 704 */ 705 rootkuid = mapped_kuid_fs(mnt_userns, fs_ns, rootkuid); 706 if (!rootid_owns_currentns(rootkuid)) 707 return -ENODATA; 708 709 CAP_FOR_EACH_U32(i) { 710 if (i >= tocopy) 711 break; 712 cpu_caps->permitted.cap[i] = le32_to_cpu(caps->data[i].permitted); 713 cpu_caps->inheritable.cap[i] = le32_to_cpu(caps->data[i].inheritable); 714 } 715 716 cpu_caps->permitted.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK; 717 cpu_caps->inheritable.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK; 718 719 cpu_caps->rootid = rootkuid; 720 721 return 0; 722 } 723 724 /* 725 * Attempt to get the on-exec apply capability sets for an executable file from 726 * its xattrs and, if present, apply them to the proposed credentials being 727 * constructed by execve(). 728 */ 729 static int get_file_caps(struct linux_binprm *bprm, struct file *file, 730 bool *effective, bool *has_fcap) 731 { 732 int rc = 0; 733 struct cpu_vfs_cap_data vcaps; 734 735 cap_clear(bprm->cred->cap_permitted); 736 737 if (!file_caps_enabled) 738 return 0; 739 740 if (!mnt_may_suid(file->f_path.mnt)) 741 return 0; 742 743 /* 744 * This check is redundant with mnt_may_suid() but is kept to make 745 * explicit that capability bits are limited to s_user_ns and its 746 * descendants. 747 */ 748 if (!current_in_userns(file->f_path.mnt->mnt_sb->s_user_ns)) 749 return 0; 750 751 rc = get_vfs_caps_from_disk(file_mnt_user_ns(file), 752 file->f_path.dentry, &vcaps); 753 if (rc < 0) { 754 if (rc == -EINVAL) 755 printk(KERN_NOTICE "Invalid argument reading file caps for %s\n", 756 bprm->filename); 757 else if (rc == -ENODATA) 758 rc = 0; 759 goto out; 760 } 761 762 rc = bprm_caps_from_vfs_caps(&vcaps, bprm, effective, has_fcap); 763 764 out: 765 if (rc) 766 cap_clear(bprm->cred->cap_permitted); 767 768 return rc; 769 } 770 771 static inline bool root_privileged(void) { return !issecure(SECURE_NOROOT); } 772 773 static inline bool __is_real(kuid_t uid, struct cred *cred) 774 { return uid_eq(cred->uid, uid); } 775 776 static inline bool __is_eff(kuid_t uid, struct cred *cred) 777 { return uid_eq(cred->euid, uid); } 778 779 static inline bool __is_suid(kuid_t uid, struct cred *cred) 780 { return !__is_real(uid, cred) && __is_eff(uid, cred); } 781 782 /* 783 * handle_privileged_root - Handle case of privileged root 784 * @bprm: The execution parameters, including the proposed creds 785 * @has_fcap: Are any file capabilities set? 786 * @effective: Do we have effective root privilege? 787 * @root_uid: This namespace' root UID WRT initial USER namespace 788 * 789 * Handle the case where root is privileged and hasn't been neutered by 790 * SECURE_NOROOT. If file capabilities are set, they won't be combined with 791 * set UID root and nothing is changed. If we are root, cap_permitted is 792 * updated. If we have become set UID root, the effective bit is set. 793 */ 794 static void handle_privileged_root(struct linux_binprm *bprm, bool has_fcap, 795 bool *effective, kuid_t root_uid) 796 { 797 const struct cred *old = current_cred(); 798 struct cred *new = bprm->cred; 799 800 if (!root_privileged()) 801 return; 802 /* 803 * If the legacy file capability is set, then don't set privs 804 * for a setuid root binary run by a non-root user. Do set it 805 * for a root user just to cause least surprise to an admin. 806 */ 807 if (has_fcap && __is_suid(root_uid, new)) { 808 warn_setuid_and_fcaps_mixed(bprm->filename); 809 return; 810 } 811 /* 812 * To support inheritance of root-permissions and suid-root 813 * executables under compatibility mode, we override the 814 * capability sets for the file. 815 */ 816 if (__is_eff(root_uid, new) || __is_real(root_uid, new)) { 817 /* pP' = (cap_bset & ~0) | (pI & ~0) */ 818 new->cap_permitted = cap_combine(old->cap_bset, 819 old->cap_inheritable); 820 } 821 /* 822 * If only the real uid is 0, we do not set the effective bit. 823 */ 824 if (__is_eff(root_uid, new)) 825 *effective = true; 826 } 827 828 #define __cap_gained(field, target, source) \ 829 !cap_issubset(target->cap_##field, source->cap_##field) 830 #define __cap_grew(target, source, cred) \ 831 !cap_issubset(cred->cap_##target, cred->cap_##source) 832 #define __cap_full(field, cred) \ 833 cap_issubset(CAP_FULL_SET, cred->cap_##field) 834 835 static inline bool __is_setuid(struct cred *new, const struct cred *old) 836 { return !uid_eq(new->euid, old->uid); } 837 838 static inline bool __is_setgid(struct cred *new, const struct cred *old) 839 { return !gid_eq(new->egid, old->gid); } 840 841 /* 842 * 1) Audit candidate if current->cap_effective is set 843 * 844 * We do not bother to audit if 3 things are true: 845 * 1) cap_effective has all caps 846 * 2) we became root *OR* are were already root 847 * 3) root is supposed to have all caps (SECURE_NOROOT) 848 * Since this is just a normal root execing a process. 849 * 850 * Number 1 above might fail if you don't have a full bset, but I think 851 * that is interesting information to audit. 852 * 853 * A number of other conditions require logging: 854 * 2) something prevented setuid root getting all caps 855 * 3) non-setuid root gets fcaps 856 * 4) non-setuid root gets ambient 857 */ 858 static inline bool nonroot_raised_pE(struct cred *new, const struct cred *old, 859 kuid_t root, bool has_fcap) 860 { 861 bool ret = false; 862 863 if ((__cap_grew(effective, ambient, new) && 864 !(__cap_full(effective, new) && 865 (__is_eff(root, new) || __is_real(root, new)) && 866 root_privileged())) || 867 (root_privileged() && 868 __is_suid(root, new) && 869 !__cap_full(effective, new)) || 870 (!__is_setuid(new, old) && 871 ((has_fcap && 872 __cap_gained(permitted, new, old)) || 873 __cap_gained(ambient, new, old)))) 874 875 ret = true; 876 877 return ret; 878 } 879 880 /** 881 * cap_bprm_creds_from_file - Set up the proposed credentials for execve(). 882 * @bprm: The execution parameters, including the proposed creds 883 * @file: The file to pull the credentials from 884 * 885 * Set up the proposed credentials for a new execution context being 886 * constructed by execve(). The proposed creds in @bprm->cred is altered, 887 * which won't take effect immediately. 888 * 889 * Return: 0 if successful, -ve on error. 890 */ 891 int cap_bprm_creds_from_file(struct linux_binprm *bprm, struct file *file) 892 { 893 /* Process setpcap binaries and capabilities for uid 0 */ 894 const struct cred *old = current_cred(); 895 struct cred *new = bprm->cred; 896 bool effective = false, has_fcap = false, is_setid; 897 int ret; 898 kuid_t root_uid; 899 900 if (WARN_ON(!cap_ambient_invariant_ok(old))) 901 return -EPERM; 902 903 ret = get_file_caps(bprm, file, &effective, &has_fcap); 904 if (ret < 0) 905 return ret; 906 907 root_uid = make_kuid(new->user_ns, 0); 908 909 handle_privileged_root(bprm, has_fcap, &effective, root_uid); 910 911 /* if we have fs caps, clear dangerous personality flags */ 912 if (__cap_gained(permitted, new, old)) 913 bprm->per_clear |= PER_CLEAR_ON_SETID; 914 915 /* Don't let someone trace a set[ug]id/setpcap binary with the revised 916 * credentials unless they have the appropriate permit. 917 * 918 * In addition, if NO_NEW_PRIVS, then ensure we get no new privs. 919 */ 920 is_setid = __is_setuid(new, old) || __is_setgid(new, old); 921 922 if ((is_setid || __cap_gained(permitted, new, old)) && 923 ((bprm->unsafe & ~LSM_UNSAFE_PTRACE) || 924 !ptracer_capable(current, new->user_ns))) { 925 /* downgrade; they get no more than they had, and maybe less */ 926 if (!ns_capable(new->user_ns, CAP_SETUID) || 927 (bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS)) { 928 new->euid = new->uid; 929 new->egid = new->gid; 930 } 931 new->cap_permitted = cap_intersect(new->cap_permitted, 932 old->cap_permitted); 933 } 934 935 new->suid = new->fsuid = new->euid; 936 new->sgid = new->fsgid = new->egid; 937 938 /* File caps or setid cancels ambient. */ 939 if (has_fcap || is_setid) 940 cap_clear(new->cap_ambient); 941 942 /* 943 * Now that we've computed pA', update pP' to give: 944 * pP' = (X & fP) | (pI & fI) | pA' 945 */ 946 new->cap_permitted = cap_combine(new->cap_permitted, new->cap_ambient); 947 948 /* 949 * Set pE' = (fE ? pP' : pA'). Because pA' is zero if fE is set, 950 * this is the same as pE' = (fE ? pP' : 0) | pA'. 951 */ 952 if (effective) 953 new->cap_effective = new->cap_permitted; 954 else 955 new->cap_effective = new->cap_ambient; 956 957 if (WARN_ON(!cap_ambient_invariant_ok(new))) 958 return -EPERM; 959 960 if (nonroot_raised_pE(new, old, root_uid, has_fcap)) { 961 ret = audit_log_bprm_fcaps(bprm, new, old); 962 if (ret < 0) 963 return ret; 964 } 965 966 new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS); 967 968 if (WARN_ON(!cap_ambient_invariant_ok(new))) 969 return -EPERM; 970 971 /* Check for privilege-elevated exec. */ 972 if (is_setid || 973 (!__is_real(root_uid, new) && 974 (effective || 975 __cap_grew(permitted, ambient, new)))) 976 bprm->secureexec = 1; 977 978 return 0; 979 } 980 981 /** 982 * cap_inode_setxattr - Determine whether an xattr may be altered 983 * @dentry: The inode/dentry being altered 984 * @name: The name of the xattr to be changed 985 * @value: The value that the xattr will be changed to 986 * @size: The size of value 987 * @flags: The replacement flag 988 * 989 * Determine whether an xattr may be altered or set on an inode, returning 0 if 990 * permission is granted, -ve if denied. 991 * 992 * This is used to make sure security xattrs don't get updated or set by those 993 * who aren't privileged to do so. 994 */ 995 int cap_inode_setxattr(struct dentry *dentry, const char *name, 996 const void *value, size_t size, int flags) 997 { 998 struct user_namespace *user_ns = dentry->d_sb->s_user_ns; 999 1000 /* Ignore non-security xattrs */ 1001 if (strncmp(name, XATTR_SECURITY_PREFIX, 1002 XATTR_SECURITY_PREFIX_LEN) != 0) 1003 return 0; 1004 1005 /* 1006 * For XATTR_NAME_CAPS the check will be done in 1007 * cap_convert_nscap(), called by setxattr() 1008 */ 1009 if (strcmp(name, XATTR_NAME_CAPS) == 0) 1010 return 0; 1011 1012 if (!ns_capable(user_ns, CAP_SYS_ADMIN)) 1013 return -EPERM; 1014 return 0; 1015 } 1016 1017 /** 1018 * cap_inode_removexattr - Determine whether an xattr may be removed 1019 * 1020 * @mnt_userns: User namespace of the mount the inode was found from 1021 * @dentry: The inode/dentry being altered 1022 * @name: The name of the xattr to be changed 1023 * 1024 * Determine whether an xattr may be removed from an inode, returning 0 if 1025 * permission is granted, -ve if denied. 1026 * 1027 * If the inode has been found through an idmapped mount the user namespace of 1028 * the vfsmount must be passed through @mnt_userns. This function will then 1029 * take care to map the inode according to @mnt_userns before checking 1030 * permissions. On non-idmapped mounts or if permission checking is to be 1031 * performed on the raw inode simply passs init_user_ns. 1032 * 1033 * This is used to make sure security xattrs don't get removed by those who 1034 * aren't privileged to remove them. 1035 */ 1036 int cap_inode_removexattr(struct user_namespace *mnt_userns, 1037 struct dentry *dentry, const char *name) 1038 { 1039 struct user_namespace *user_ns = dentry->d_sb->s_user_ns; 1040 1041 /* Ignore non-security xattrs */ 1042 if (strncmp(name, XATTR_SECURITY_PREFIX, 1043 XATTR_SECURITY_PREFIX_LEN) != 0) 1044 return 0; 1045 1046 if (strcmp(name, XATTR_NAME_CAPS) == 0) { 1047 /* security.capability gets namespaced */ 1048 struct inode *inode = d_backing_inode(dentry); 1049 if (!inode) 1050 return -EINVAL; 1051 if (!capable_wrt_inode_uidgid(mnt_userns, inode, CAP_SETFCAP)) 1052 return -EPERM; 1053 return 0; 1054 } 1055 1056 if (!ns_capable(user_ns, CAP_SYS_ADMIN)) 1057 return -EPERM; 1058 return 0; 1059 } 1060 1061 /* 1062 * cap_emulate_setxuid() fixes the effective / permitted capabilities of 1063 * a process after a call to setuid, setreuid, or setresuid. 1064 * 1065 * 1) When set*uiding _from_ one of {r,e,s}uid == 0 _to_ all of 1066 * {r,e,s}uid != 0, the permitted and effective capabilities are 1067 * cleared. 1068 * 1069 * 2) When set*uiding _from_ euid == 0 _to_ euid != 0, the effective 1070 * capabilities of the process are cleared. 1071 * 1072 * 3) When set*uiding _from_ euid != 0 _to_ euid == 0, the effective 1073 * capabilities are set to the permitted capabilities. 1074 * 1075 * fsuid is handled elsewhere. fsuid == 0 and {r,e,s}uid!= 0 should 1076 * never happen. 1077 * 1078 * -astor 1079 * 1080 * cevans - New behaviour, Oct '99 1081 * A process may, via prctl(), elect to keep its capabilities when it 1082 * calls setuid() and switches away from uid==0. Both permitted and 1083 * effective sets will be retained. 1084 * Without this change, it was impossible for a daemon to drop only some 1085 * of its privilege. The call to setuid(!=0) would drop all privileges! 1086 * Keeping uid 0 is not an option because uid 0 owns too many vital 1087 * files.. 1088 * Thanks to Olaf Kirch and Peter Benie for spotting this. 1089 */ 1090 static inline void cap_emulate_setxuid(struct cred *new, const struct cred *old) 1091 { 1092 kuid_t root_uid = make_kuid(old->user_ns, 0); 1093 1094 if ((uid_eq(old->uid, root_uid) || 1095 uid_eq(old->euid, root_uid) || 1096 uid_eq(old->suid, root_uid)) && 1097 (!uid_eq(new->uid, root_uid) && 1098 !uid_eq(new->euid, root_uid) && 1099 !uid_eq(new->suid, root_uid))) { 1100 if (!issecure(SECURE_KEEP_CAPS)) { 1101 cap_clear(new->cap_permitted); 1102 cap_clear(new->cap_effective); 1103 } 1104 1105 /* 1106 * Pre-ambient programs expect setresuid to nonroot followed 1107 * by exec to drop capabilities. We should make sure that 1108 * this remains the case. 1109 */ 1110 cap_clear(new->cap_ambient); 1111 } 1112 if (uid_eq(old->euid, root_uid) && !uid_eq(new->euid, root_uid)) 1113 cap_clear(new->cap_effective); 1114 if (!uid_eq(old->euid, root_uid) && uid_eq(new->euid, root_uid)) 1115 new->cap_effective = new->cap_permitted; 1116 } 1117 1118 /** 1119 * cap_task_fix_setuid - Fix up the results of setuid() call 1120 * @new: The proposed credentials 1121 * @old: The current task's current credentials 1122 * @flags: Indications of what has changed 1123 * 1124 * Fix up the results of setuid() call before the credential changes are 1125 * actually applied. 1126 * 1127 * Return: 0 to grant the changes, -ve to deny them. 1128 */ 1129 int cap_task_fix_setuid(struct cred *new, const struct cred *old, int flags) 1130 { 1131 switch (flags) { 1132 case LSM_SETID_RE: 1133 case LSM_SETID_ID: 1134 case LSM_SETID_RES: 1135 /* juggle the capabilities to follow [RES]UID changes unless 1136 * otherwise suppressed */ 1137 if (!issecure(SECURE_NO_SETUID_FIXUP)) 1138 cap_emulate_setxuid(new, old); 1139 break; 1140 1141 case LSM_SETID_FS: 1142 /* juggle the capabilties to follow FSUID changes, unless 1143 * otherwise suppressed 1144 * 1145 * FIXME - is fsuser used for all CAP_FS_MASK capabilities? 1146 * if not, we might be a bit too harsh here. 1147 */ 1148 if (!issecure(SECURE_NO_SETUID_FIXUP)) { 1149 kuid_t root_uid = make_kuid(old->user_ns, 0); 1150 if (uid_eq(old->fsuid, root_uid) && !uid_eq(new->fsuid, root_uid)) 1151 new->cap_effective = 1152 cap_drop_fs_set(new->cap_effective); 1153 1154 if (!uid_eq(old->fsuid, root_uid) && uid_eq(new->fsuid, root_uid)) 1155 new->cap_effective = 1156 cap_raise_fs_set(new->cap_effective, 1157 new->cap_permitted); 1158 } 1159 break; 1160 1161 default: 1162 return -EINVAL; 1163 } 1164 1165 return 0; 1166 } 1167 1168 /* 1169 * Rationale: code calling task_setscheduler, task_setioprio, and 1170 * task_setnice, assumes that 1171 * . if capable(cap_sys_nice), then those actions should be allowed 1172 * . if not capable(cap_sys_nice), but acting on your own processes, 1173 * then those actions should be allowed 1174 * This is insufficient now since you can call code without suid, but 1175 * yet with increased caps. 1176 * So we check for increased caps on the target process. 1177 */ 1178 static int cap_safe_nice(struct task_struct *p) 1179 { 1180 int is_subset, ret = 0; 1181 1182 rcu_read_lock(); 1183 is_subset = cap_issubset(__task_cred(p)->cap_permitted, 1184 current_cred()->cap_permitted); 1185 if (!is_subset && !ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) 1186 ret = -EPERM; 1187 rcu_read_unlock(); 1188 1189 return ret; 1190 } 1191 1192 /** 1193 * cap_task_setscheduler - Detemine if scheduler policy change is permitted 1194 * @p: The task to affect 1195 * 1196 * Detemine if the requested scheduler policy change is permitted for the 1197 * specified task. 1198 * 1199 * Return: 0 if permission is granted, -ve if denied. 1200 */ 1201 int cap_task_setscheduler(struct task_struct *p) 1202 { 1203 return cap_safe_nice(p); 1204 } 1205 1206 /** 1207 * cap_task_setioprio - Detemine if I/O priority change is permitted 1208 * @p: The task to affect 1209 * @ioprio: The I/O priority to set 1210 * 1211 * Detemine if the requested I/O priority change is permitted for the specified 1212 * task. 1213 * 1214 * Return: 0 if permission is granted, -ve if denied. 1215 */ 1216 int cap_task_setioprio(struct task_struct *p, int ioprio) 1217 { 1218 return cap_safe_nice(p); 1219 } 1220 1221 /** 1222 * cap_task_setnice - Detemine if task priority change is permitted 1223 * @p: The task to affect 1224 * @nice: The nice value to set 1225 * 1226 * Detemine if the requested task priority change is permitted for the 1227 * specified task. 1228 * 1229 * Return: 0 if permission is granted, -ve if denied. 1230 */ 1231 int cap_task_setnice(struct task_struct *p, int nice) 1232 { 1233 return cap_safe_nice(p); 1234 } 1235 1236 /* 1237 * Implement PR_CAPBSET_DROP. Attempt to remove the specified capability from 1238 * the current task's bounding set. Returns 0 on success, -ve on error. 1239 */ 1240 static int cap_prctl_drop(unsigned long cap) 1241 { 1242 struct cred *new; 1243 1244 if (!ns_capable(current_user_ns(), CAP_SETPCAP)) 1245 return -EPERM; 1246 if (!cap_valid(cap)) 1247 return -EINVAL; 1248 1249 new = prepare_creds(); 1250 if (!new) 1251 return -ENOMEM; 1252 cap_lower(new->cap_bset, cap); 1253 return commit_creds(new); 1254 } 1255 1256 /** 1257 * cap_task_prctl - Implement process control functions for this security module 1258 * @option: The process control function requested 1259 * @arg2: The argument data for this function 1260 * @arg3: The argument data for this function 1261 * @arg4: The argument data for this function 1262 * @arg5: The argument data for this function 1263 * 1264 * Allow process control functions (sys_prctl()) to alter capabilities; may 1265 * also deny access to other functions not otherwise implemented here. 1266 * 1267 * Return: 0 or +ve on success, -ENOSYS if this function is not implemented 1268 * here, other -ve on error. If -ENOSYS is returned, sys_prctl() and other LSM 1269 * modules will consider performing the function. 1270 */ 1271 int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3, 1272 unsigned long arg4, unsigned long arg5) 1273 { 1274 const struct cred *old = current_cred(); 1275 struct cred *new; 1276 1277 switch (option) { 1278 case PR_CAPBSET_READ: 1279 if (!cap_valid(arg2)) 1280 return -EINVAL; 1281 return !!cap_raised(old->cap_bset, arg2); 1282 1283 case PR_CAPBSET_DROP: 1284 return cap_prctl_drop(arg2); 1285 1286 /* 1287 * The next four prctl's remain to assist with transitioning a 1288 * system from legacy UID=0 based privilege (when filesystem 1289 * capabilities are not in use) to a system using filesystem 1290 * capabilities only - as the POSIX.1e draft intended. 1291 * 1292 * Note: 1293 * 1294 * PR_SET_SECUREBITS = 1295 * issecure_mask(SECURE_KEEP_CAPS_LOCKED) 1296 * | issecure_mask(SECURE_NOROOT) 1297 * | issecure_mask(SECURE_NOROOT_LOCKED) 1298 * | issecure_mask(SECURE_NO_SETUID_FIXUP) 1299 * | issecure_mask(SECURE_NO_SETUID_FIXUP_LOCKED) 1300 * 1301 * will ensure that the current process and all of its 1302 * children will be locked into a pure 1303 * capability-based-privilege environment. 1304 */ 1305 case PR_SET_SECUREBITS: 1306 if ((((old->securebits & SECURE_ALL_LOCKS) >> 1) 1307 & (old->securebits ^ arg2)) /*[1]*/ 1308 || ((old->securebits & SECURE_ALL_LOCKS & ~arg2)) /*[2]*/ 1309 || (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS)) /*[3]*/ 1310 || (cap_capable(current_cred(), 1311 current_cred()->user_ns, 1312 CAP_SETPCAP, 1313 CAP_OPT_NONE) != 0) /*[4]*/ 1314 /* 1315 * [1] no changing of bits that are locked 1316 * [2] no unlocking of locks 1317 * [3] no setting of unsupported bits 1318 * [4] doing anything requires privilege (go read about 1319 * the "sendmail capabilities bug") 1320 */ 1321 ) 1322 /* cannot change a locked bit */ 1323 return -EPERM; 1324 1325 new = prepare_creds(); 1326 if (!new) 1327 return -ENOMEM; 1328 new->securebits = arg2; 1329 return commit_creds(new); 1330 1331 case PR_GET_SECUREBITS: 1332 return old->securebits; 1333 1334 case PR_GET_KEEPCAPS: 1335 return !!issecure(SECURE_KEEP_CAPS); 1336 1337 case PR_SET_KEEPCAPS: 1338 if (arg2 > 1) /* Note, we rely on arg2 being unsigned here */ 1339 return -EINVAL; 1340 if (issecure(SECURE_KEEP_CAPS_LOCKED)) 1341 return -EPERM; 1342 1343 new = prepare_creds(); 1344 if (!new) 1345 return -ENOMEM; 1346 if (arg2) 1347 new->securebits |= issecure_mask(SECURE_KEEP_CAPS); 1348 else 1349 new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS); 1350 return commit_creds(new); 1351 1352 case PR_CAP_AMBIENT: 1353 if (arg2 == PR_CAP_AMBIENT_CLEAR_ALL) { 1354 if (arg3 | arg4 | arg5) 1355 return -EINVAL; 1356 1357 new = prepare_creds(); 1358 if (!new) 1359 return -ENOMEM; 1360 cap_clear(new->cap_ambient); 1361 return commit_creds(new); 1362 } 1363 1364 if (((!cap_valid(arg3)) | arg4 | arg5)) 1365 return -EINVAL; 1366 1367 if (arg2 == PR_CAP_AMBIENT_IS_SET) { 1368 return !!cap_raised(current_cred()->cap_ambient, arg3); 1369 } else if (arg2 != PR_CAP_AMBIENT_RAISE && 1370 arg2 != PR_CAP_AMBIENT_LOWER) { 1371 return -EINVAL; 1372 } else { 1373 if (arg2 == PR_CAP_AMBIENT_RAISE && 1374 (!cap_raised(current_cred()->cap_permitted, arg3) || 1375 !cap_raised(current_cred()->cap_inheritable, 1376 arg3) || 1377 issecure(SECURE_NO_CAP_AMBIENT_RAISE))) 1378 return -EPERM; 1379 1380 new = prepare_creds(); 1381 if (!new) 1382 return -ENOMEM; 1383 if (arg2 == PR_CAP_AMBIENT_RAISE) 1384 cap_raise(new->cap_ambient, arg3); 1385 else 1386 cap_lower(new->cap_ambient, arg3); 1387 return commit_creds(new); 1388 } 1389 1390 default: 1391 /* No functionality available - continue with default */ 1392 return -ENOSYS; 1393 } 1394 } 1395 1396 /** 1397 * cap_vm_enough_memory - Determine whether a new virtual mapping is permitted 1398 * @mm: The VM space in which the new mapping is to be made 1399 * @pages: The size of the mapping 1400 * 1401 * Determine whether the allocation of a new virtual mapping by the current 1402 * task is permitted. 1403 * 1404 * Return: 1 if permission is granted, 0 if not. 1405 */ 1406 int cap_vm_enough_memory(struct mm_struct *mm, long pages) 1407 { 1408 int cap_sys_admin = 0; 1409 1410 if (cap_capable(current_cred(), &init_user_ns, 1411 CAP_SYS_ADMIN, CAP_OPT_NOAUDIT) == 0) 1412 cap_sys_admin = 1; 1413 1414 return cap_sys_admin; 1415 } 1416 1417 /** 1418 * cap_mmap_addr - check if able to map given addr 1419 * @addr: address attempting to be mapped 1420 * 1421 * If the process is attempting to map memory below dac_mmap_min_addr they need 1422 * CAP_SYS_RAWIO. The other parameters to this function are unused by the 1423 * capability security module. 1424 * 1425 * Return: 0 if this mapping should be allowed or -EPERM if not. 1426 */ 1427 int cap_mmap_addr(unsigned long addr) 1428 { 1429 int ret = 0; 1430 1431 if (addr < dac_mmap_min_addr) { 1432 ret = cap_capable(current_cred(), &init_user_ns, CAP_SYS_RAWIO, 1433 CAP_OPT_NONE); 1434 /* set PF_SUPERPRIV if it turns out we allow the low mmap */ 1435 if (ret == 0) 1436 current->flags |= PF_SUPERPRIV; 1437 } 1438 return ret; 1439 } 1440 1441 int cap_mmap_file(struct file *file, unsigned long reqprot, 1442 unsigned long prot, unsigned long flags) 1443 { 1444 return 0; 1445 } 1446 1447 #ifdef CONFIG_SECURITY 1448 1449 static struct security_hook_list capability_hooks[] __lsm_ro_after_init = { 1450 LSM_HOOK_INIT(capable, cap_capable), 1451 LSM_HOOK_INIT(settime, cap_settime), 1452 LSM_HOOK_INIT(ptrace_access_check, cap_ptrace_access_check), 1453 LSM_HOOK_INIT(ptrace_traceme, cap_ptrace_traceme), 1454 LSM_HOOK_INIT(capget, cap_capget), 1455 LSM_HOOK_INIT(capset, cap_capset), 1456 LSM_HOOK_INIT(bprm_creds_from_file, cap_bprm_creds_from_file), 1457 LSM_HOOK_INIT(inode_need_killpriv, cap_inode_need_killpriv), 1458 LSM_HOOK_INIT(inode_killpriv, cap_inode_killpriv), 1459 LSM_HOOK_INIT(inode_getsecurity, cap_inode_getsecurity), 1460 LSM_HOOK_INIT(mmap_addr, cap_mmap_addr), 1461 LSM_HOOK_INIT(mmap_file, cap_mmap_file), 1462 LSM_HOOK_INIT(task_fix_setuid, cap_task_fix_setuid), 1463 LSM_HOOK_INIT(task_prctl, cap_task_prctl), 1464 LSM_HOOK_INIT(task_setscheduler, cap_task_setscheduler), 1465 LSM_HOOK_INIT(task_setioprio, cap_task_setioprio), 1466 LSM_HOOK_INIT(task_setnice, cap_task_setnice), 1467 LSM_HOOK_INIT(vm_enough_memory, cap_vm_enough_memory), 1468 }; 1469 1470 static int __init capability_init(void) 1471 { 1472 security_add_hooks(capability_hooks, ARRAY_SIZE(capability_hooks), 1473 "capability"); 1474 return 0; 1475 } 1476 1477 DEFINE_LSM(capability) = { 1478 .name = "capability", 1479 .order = LSM_ORDER_FIRST, 1480 .init = capability_init, 1481 }; 1482 1483 #endif /* CONFIG_SECURITY */ 1484