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(int 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(int 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; 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 size = vfs_getxattr_alloc(mnt_userns, dentry, XATTR_NAME_CAPS, &tmpbuf, 399 sizeof(struct vfs_ns_cap_data), GFP_NOFS); 400 dput(dentry); 401 /* gcc11 complains if we don't check for !tmpbuf */ 402 if (size < 0 || !tmpbuf) 403 goto out_free; 404 405 fs_ns = inode->i_sb->s_user_ns; 406 cap = (struct vfs_cap_data *) tmpbuf; 407 if (is_v2header(size, cap)) { 408 root = 0; 409 } else if (is_v3header(size, cap)) { 410 nscap = (struct vfs_ns_cap_data *) tmpbuf; 411 root = le32_to_cpu(nscap->rootid); 412 } else { 413 size = -EINVAL; 414 goto out_free; 415 } 416 417 kroot = make_kuid(fs_ns, root); 418 419 /* If this is an idmapped mount shift the kuid. */ 420 kroot = mapped_kuid_fs(mnt_userns, fs_ns, kroot); 421 422 /* If the root kuid maps to a valid uid in current ns, then return 423 * this as a nscap. */ 424 mappedroot = from_kuid(current_user_ns(), kroot); 425 if (mappedroot != (uid_t)-1 && mappedroot != (uid_t)0) { 426 size = sizeof(struct vfs_ns_cap_data); 427 if (alloc) { 428 if (!nscap) { 429 /* v2 -> v3 conversion */ 430 nscap = kzalloc(size, GFP_ATOMIC); 431 if (!nscap) { 432 size = -ENOMEM; 433 goto out_free; 434 } 435 nsmagic = VFS_CAP_REVISION_3; 436 magic = le32_to_cpu(cap->magic_etc); 437 if (magic & VFS_CAP_FLAGS_EFFECTIVE) 438 nsmagic |= VFS_CAP_FLAGS_EFFECTIVE; 439 memcpy(&nscap->data, &cap->data, sizeof(__le32) * 2 * VFS_CAP_U32); 440 nscap->magic_etc = cpu_to_le32(nsmagic); 441 } else { 442 /* use allocated v3 buffer */ 443 tmpbuf = NULL; 444 } 445 nscap->rootid = cpu_to_le32(mappedroot); 446 *buffer = nscap; 447 } 448 goto out_free; 449 } 450 451 if (!rootid_owns_currentns(kroot)) { 452 size = -EOVERFLOW; 453 goto out_free; 454 } 455 456 /* This comes from a parent namespace. Return as a v2 capability */ 457 size = sizeof(struct vfs_cap_data); 458 if (alloc) { 459 if (nscap) { 460 /* v3 -> v2 conversion */ 461 cap = kzalloc(size, GFP_ATOMIC); 462 if (!cap) { 463 size = -ENOMEM; 464 goto out_free; 465 } 466 magic = VFS_CAP_REVISION_2; 467 nsmagic = le32_to_cpu(nscap->magic_etc); 468 if (nsmagic & VFS_CAP_FLAGS_EFFECTIVE) 469 magic |= VFS_CAP_FLAGS_EFFECTIVE; 470 memcpy(&cap->data, &nscap->data, sizeof(__le32) * 2 * VFS_CAP_U32); 471 cap->magic_etc = cpu_to_le32(magic); 472 } else { 473 /* use unconverted v2 */ 474 tmpbuf = NULL; 475 } 476 *buffer = cap; 477 } 478 out_free: 479 kfree(tmpbuf); 480 return size; 481 } 482 483 /** 484 * rootid_from_xattr - translate root uid of vfs caps 485 * 486 * @value: vfs caps value which may be modified by this function 487 * @size: size of @ivalue 488 * @task_ns: user namespace of the caller 489 * @mnt_userns: user namespace of the mount the inode was found from 490 * @fs_userns: user namespace of the filesystem 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 struct user_namespace *fs_userns) 502 { 503 const struct vfs_ns_cap_data *nscap = value; 504 kuid_t rootkid; 505 uid_t rootid = 0; 506 507 if (size == XATTR_CAPS_SZ_3) 508 rootid = le32_to_cpu(nscap->rootid); 509 510 rootkid = make_kuid(task_ns, rootid); 511 return mapped_kuid_user(mnt_userns, fs_userns, rootkid); 512 } 513 514 static bool validheader(size_t size, const struct vfs_cap_data *cap) 515 { 516 return is_v2header(size, cap) || is_v3header(size, cap); 517 } 518 519 /** 520 * cap_convert_nscap - check vfs caps 521 * 522 * @mnt_userns: user namespace of the mount the inode was found from 523 * @dentry: used to retrieve inode to check permissions on 524 * @ivalue: vfs caps value which may be modified by this function 525 * @size: size of @ivalue 526 * 527 * User requested a write of security.capability. If needed, update the 528 * xattr to change from v2 to v3, or to fixup the v3 rootid. 529 * 530 * If the inode has been found through an idmapped mount the user namespace of 531 * the vfsmount must be passed through @mnt_userns. This function will then 532 * take care to map the inode according to @mnt_userns before checking 533 * permissions. On non-idmapped mounts or if permission checking is to be 534 * performed on the raw inode simply passs init_user_ns. 535 * 536 * Return: On success, return the new size; on error, return < 0. 537 */ 538 int cap_convert_nscap(struct user_namespace *mnt_userns, struct dentry *dentry, 539 const void **ivalue, size_t size) 540 { 541 struct vfs_ns_cap_data *nscap; 542 uid_t nsrootid; 543 const struct vfs_cap_data *cap = *ivalue; 544 __u32 magic, nsmagic; 545 struct inode *inode = d_backing_inode(dentry); 546 struct user_namespace *task_ns = current_user_ns(), 547 *fs_ns = inode->i_sb->s_user_ns; 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 == fs_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, fs_ns); 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 newsize = sizeof(struct vfs_ns_cap_data); 571 nscap = kmalloc(newsize, GFP_ATOMIC); 572 if (!nscap) 573 return -ENOMEM; 574 nscap->rootid = cpu_to_le32(nsrootid); 575 nsmagic = VFS_CAP_REVISION_3; 576 magic = le32_to_cpu(cap->magic_etc); 577 if (magic & VFS_CAP_FLAGS_EFFECTIVE) 578 nsmagic |= VFS_CAP_FLAGS_EFFECTIVE; 579 nscap->magic_etc = cpu_to_le32(nsmagic); 580 memcpy(&nscap->data, &cap->data, sizeof(__le32) * 2 * VFS_CAP_U32); 581 582 *ivalue = nscap; 583 return newsize; 584 } 585 586 /* 587 * Calculate the new process capability sets from the capability sets attached 588 * to a file. 589 */ 590 static inline int bprm_caps_from_vfs_caps(struct cpu_vfs_cap_data *caps, 591 struct linux_binprm *bprm, 592 bool *effective, 593 bool *has_fcap) 594 { 595 struct cred *new = bprm->cred; 596 unsigned i; 597 int ret = 0; 598 599 if (caps->magic_etc & VFS_CAP_FLAGS_EFFECTIVE) 600 *effective = true; 601 602 if (caps->magic_etc & VFS_CAP_REVISION_MASK) 603 *has_fcap = true; 604 605 CAP_FOR_EACH_U32(i) { 606 __u32 permitted = caps->permitted.cap[i]; 607 __u32 inheritable = caps->inheritable.cap[i]; 608 609 /* 610 * pP' = (X & fP) | (pI & fI) 611 * The addition of pA' is handled later. 612 */ 613 new->cap_permitted.cap[i] = 614 (new->cap_bset.cap[i] & permitted) | 615 (new->cap_inheritable.cap[i] & inheritable); 616 617 if (permitted & ~new->cap_permitted.cap[i]) 618 /* insufficient to execute correctly */ 619 ret = -EPERM; 620 } 621 622 /* 623 * For legacy apps, with no internal support for recognizing they 624 * do not have enough capabilities, we return an error if they are 625 * missing some "forced" (aka file-permitted) capabilities. 626 */ 627 return *effective ? ret : 0; 628 } 629 630 /** 631 * get_vfs_caps_from_disk - retrieve vfs caps from disk 632 * 633 * @mnt_userns: user namespace of the mount the inode was found from 634 * @dentry: dentry from which @inode is retrieved 635 * @cpu_caps: vfs capabilities 636 * 637 * Extract the on-exec-apply capability sets for an executable file. 638 * 639 * If the inode has been found through an idmapped mount the user namespace of 640 * the vfsmount must be passed through @mnt_userns. This function will then 641 * take care to map the inode according to @mnt_userns before checking 642 * permissions. On non-idmapped mounts or if permission checking is to be 643 * performed on the raw inode simply passs init_user_ns. 644 */ 645 int get_vfs_caps_from_disk(struct user_namespace *mnt_userns, 646 const struct dentry *dentry, 647 struct cpu_vfs_cap_data *cpu_caps) 648 { 649 struct inode *inode = d_backing_inode(dentry); 650 __u32 magic_etc; 651 unsigned tocopy, i; 652 int size; 653 struct vfs_ns_cap_data data, *nscaps = &data; 654 struct vfs_cap_data *caps = (struct vfs_cap_data *) &data; 655 kuid_t rootkuid; 656 struct user_namespace *fs_ns; 657 658 memset(cpu_caps, 0, sizeof(struct cpu_vfs_cap_data)); 659 660 if (!inode) 661 return -ENODATA; 662 663 fs_ns = inode->i_sb->s_user_ns; 664 size = __vfs_getxattr((struct dentry *)dentry, inode, 665 XATTR_NAME_CAPS, &data, XATTR_CAPS_SZ); 666 if (size == -ENODATA || size == -EOPNOTSUPP) 667 /* no data, that's ok */ 668 return -ENODATA; 669 670 if (size < 0) 671 return size; 672 673 if (size < sizeof(magic_etc)) 674 return -EINVAL; 675 676 cpu_caps->magic_etc = magic_etc = le32_to_cpu(caps->magic_etc); 677 678 rootkuid = make_kuid(fs_ns, 0); 679 switch (magic_etc & VFS_CAP_REVISION_MASK) { 680 case VFS_CAP_REVISION_1: 681 if (size != XATTR_CAPS_SZ_1) 682 return -EINVAL; 683 tocopy = VFS_CAP_U32_1; 684 break; 685 case VFS_CAP_REVISION_2: 686 if (size != XATTR_CAPS_SZ_2) 687 return -EINVAL; 688 tocopy = VFS_CAP_U32_2; 689 break; 690 case VFS_CAP_REVISION_3: 691 if (size != XATTR_CAPS_SZ_3) 692 return -EINVAL; 693 tocopy = VFS_CAP_U32_3; 694 rootkuid = make_kuid(fs_ns, le32_to_cpu(nscaps->rootid)); 695 break; 696 697 default: 698 return -EINVAL; 699 } 700 /* Limit the caps to the mounter of the filesystem 701 * or the more limited uid specified in the xattr. 702 */ 703 rootkuid = mapped_kuid_fs(mnt_userns, fs_ns, rootkuid); 704 if (!rootid_owns_currentns(rootkuid)) 705 return -ENODATA; 706 707 CAP_FOR_EACH_U32(i) { 708 if (i >= tocopy) 709 break; 710 cpu_caps->permitted.cap[i] = le32_to_cpu(caps->data[i].permitted); 711 cpu_caps->inheritable.cap[i] = le32_to_cpu(caps->data[i].inheritable); 712 } 713 714 cpu_caps->permitted.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK; 715 cpu_caps->inheritable.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK; 716 717 cpu_caps->rootid = rootkuid; 718 719 return 0; 720 } 721 722 /* 723 * Attempt to get the on-exec apply capability sets for an executable file from 724 * its xattrs and, if present, apply them to the proposed credentials being 725 * constructed by execve(). 726 */ 727 static int get_file_caps(struct linux_binprm *bprm, struct file *file, 728 bool *effective, bool *has_fcap) 729 { 730 int rc = 0; 731 struct cpu_vfs_cap_data vcaps; 732 733 cap_clear(bprm->cred->cap_permitted); 734 735 if (!file_caps_enabled) 736 return 0; 737 738 if (!mnt_may_suid(file->f_path.mnt)) 739 return 0; 740 741 /* 742 * This check is redundant with mnt_may_suid() but is kept to make 743 * explicit that capability bits are limited to s_user_ns and its 744 * descendants. 745 */ 746 if (!current_in_userns(file->f_path.mnt->mnt_sb->s_user_ns)) 747 return 0; 748 749 rc = get_vfs_caps_from_disk(file_mnt_user_ns(file), 750 file->f_path.dentry, &vcaps); 751 if (rc < 0) { 752 if (rc == -EINVAL) 753 printk(KERN_NOTICE "Invalid argument reading file caps for %s\n", 754 bprm->filename); 755 else if (rc == -ENODATA) 756 rc = 0; 757 goto out; 758 } 759 760 rc = bprm_caps_from_vfs_caps(&vcaps, bprm, effective, has_fcap); 761 762 out: 763 if (rc) 764 cap_clear(bprm->cred->cap_permitted); 765 766 return rc; 767 } 768 769 static inline bool root_privileged(void) { return !issecure(SECURE_NOROOT); } 770 771 static inline bool __is_real(kuid_t uid, struct cred *cred) 772 { return uid_eq(cred->uid, uid); } 773 774 static inline bool __is_eff(kuid_t uid, struct cred *cred) 775 { return uid_eq(cred->euid, uid); } 776 777 static inline bool __is_suid(kuid_t uid, struct cred *cred) 778 { return !__is_real(uid, cred) && __is_eff(uid, cred); } 779 780 /* 781 * handle_privileged_root - Handle case of privileged root 782 * @bprm: The execution parameters, including the proposed creds 783 * @has_fcap: Are any file capabilities set? 784 * @effective: Do we have effective root privilege? 785 * @root_uid: This namespace' root UID WRT initial USER namespace 786 * 787 * Handle the case where root is privileged and hasn't been neutered by 788 * SECURE_NOROOT. If file capabilities are set, they won't be combined with 789 * set UID root and nothing is changed. If we are root, cap_permitted is 790 * updated. If we have become set UID root, the effective bit is set. 791 */ 792 static void handle_privileged_root(struct linux_binprm *bprm, bool has_fcap, 793 bool *effective, kuid_t root_uid) 794 { 795 const struct cred *old = current_cred(); 796 struct cred *new = bprm->cred; 797 798 if (!root_privileged()) 799 return; 800 /* 801 * If the legacy file capability is set, then don't set privs 802 * for a setuid root binary run by a non-root user. Do set it 803 * for a root user just to cause least surprise to an admin. 804 */ 805 if (has_fcap && __is_suid(root_uid, new)) { 806 warn_setuid_and_fcaps_mixed(bprm->filename); 807 return; 808 } 809 /* 810 * To support inheritance of root-permissions and suid-root 811 * executables under compatibility mode, we override the 812 * capability sets for the file. 813 */ 814 if (__is_eff(root_uid, new) || __is_real(root_uid, new)) { 815 /* pP' = (cap_bset & ~0) | (pI & ~0) */ 816 new->cap_permitted = cap_combine(old->cap_bset, 817 old->cap_inheritable); 818 } 819 /* 820 * If only the real uid is 0, we do not set the effective bit. 821 */ 822 if (__is_eff(root_uid, new)) 823 *effective = true; 824 } 825 826 #define __cap_gained(field, target, source) \ 827 !cap_issubset(target->cap_##field, source->cap_##field) 828 #define __cap_grew(target, source, cred) \ 829 !cap_issubset(cred->cap_##target, cred->cap_##source) 830 #define __cap_full(field, cred) \ 831 cap_issubset(CAP_FULL_SET, cred->cap_##field) 832 833 static inline bool __is_setuid(struct cred *new, const struct cred *old) 834 { return !uid_eq(new->euid, old->uid); } 835 836 static inline bool __is_setgid(struct cred *new, const struct cred *old) 837 { return !gid_eq(new->egid, old->gid); } 838 839 /* 840 * 1) Audit candidate if current->cap_effective is set 841 * 842 * We do not bother to audit if 3 things are true: 843 * 1) cap_effective has all caps 844 * 2) we became root *OR* are were already root 845 * 3) root is supposed to have all caps (SECURE_NOROOT) 846 * Since this is just a normal root execing a process. 847 * 848 * Number 1 above might fail if you don't have a full bset, but I think 849 * that is interesting information to audit. 850 * 851 * A number of other conditions require logging: 852 * 2) something prevented setuid root getting all caps 853 * 3) non-setuid root gets fcaps 854 * 4) non-setuid root gets ambient 855 */ 856 static inline bool nonroot_raised_pE(struct cred *new, const struct cred *old, 857 kuid_t root, bool has_fcap) 858 { 859 bool ret = false; 860 861 if ((__cap_grew(effective, ambient, new) && 862 !(__cap_full(effective, new) && 863 (__is_eff(root, new) || __is_real(root, new)) && 864 root_privileged())) || 865 (root_privileged() && 866 __is_suid(root, new) && 867 !__cap_full(effective, new)) || 868 (!__is_setuid(new, old) && 869 ((has_fcap && 870 __cap_gained(permitted, new, old)) || 871 __cap_gained(ambient, new, old)))) 872 873 ret = true; 874 875 return ret; 876 } 877 878 /** 879 * cap_bprm_creds_from_file - Set up the proposed credentials for execve(). 880 * @bprm: The execution parameters, including the proposed creds 881 * @file: The file to pull the credentials from 882 * 883 * Set up the proposed credentials for a new execution context being 884 * constructed by execve(). The proposed creds in @bprm->cred is altered, 885 * which won't take effect immediately. 886 * 887 * Return: 0 if successful, -ve on error. 888 */ 889 int cap_bprm_creds_from_file(struct linux_binprm *bprm, struct file *file) 890 { 891 /* Process setpcap binaries and capabilities for uid 0 */ 892 const struct cred *old = current_cred(); 893 struct cred *new = bprm->cred; 894 bool effective = false, has_fcap = false, is_setid; 895 int ret; 896 kuid_t root_uid; 897 898 if (WARN_ON(!cap_ambient_invariant_ok(old))) 899 return -EPERM; 900 901 ret = get_file_caps(bprm, file, &effective, &has_fcap); 902 if (ret < 0) 903 return ret; 904 905 root_uid = make_kuid(new->user_ns, 0); 906 907 handle_privileged_root(bprm, has_fcap, &effective, root_uid); 908 909 /* if we have fs caps, clear dangerous personality flags */ 910 if (__cap_gained(permitted, new, old)) 911 bprm->per_clear |= PER_CLEAR_ON_SETID; 912 913 /* Don't let someone trace a set[ug]id/setpcap binary with the revised 914 * credentials unless they have the appropriate permit. 915 * 916 * In addition, if NO_NEW_PRIVS, then ensure we get no new privs. 917 */ 918 is_setid = __is_setuid(new, old) || __is_setgid(new, old); 919 920 if ((is_setid || __cap_gained(permitted, new, old)) && 921 ((bprm->unsafe & ~LSM_UNSAFE_PTRACE) || 922 !ptracer_capable(current, new->user_ns))) { 923 /* downgrade; they get no more than they had, and maybe less */ 924 if (!ns_capable(new->user_ns, CAP_SETUID) || 925 (bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS)) { 926 new->euid = new->uid; 927 new->egid = new->gid; 928 } 929 new->cap_permitted = cap_intersect(new->cap_permitted, 930 old->cap_permitted); 931 } 932 933 new->suid = new->fsuid = new->euid; 934 new->sgid = new->fsgid = new->egid; 935 936 /* File caps or setid cancels ambient. */ 937 if (has_fcap || is_setid) 938 cap_clear(new->cap_ambient); 939 940 /* 941 * Now that we've computed pA', update pP' to give: 942 * pP' = (X & fP) | (pI & fI) | pA' 943 */ 944 new->cap_permitted = cap_combine(new->cap_permitted, new->cap_ambient); 945 946 /* 947 * Set pE' = (fE ? pP' : pA'). Because pA' is zero if fE is set, 948 * this is the same as pE' = (fE ? pP' : 0) | pA'. 949 */ 950 if (effective) 951 new->cap_effective = new->cap_permitted; 952 else 953 new->cap_effective = new->cap_ambient; 954 955 if (WARN_ON(!cap_ambient_invariant_ok(new))) 956 return -EPERM; 957 958 if (nonroot_raised_pE(new, old, root_uid, has_fcap)) { 959 ret = audit_log_bprm_fcaps(bprm, new, old); 960 if (ret < 0) 961 return ret; 962 } 963 964 new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS); 965 966 if (WARN_ON(!cap_ambient_invariant_ok(new))) 967 return -EPERM; 968 969 /* Check for privilege-elevated exec. */ 970 if (is_setid || 971 (!__is_real(root_uid, new) && 972 (effective || 973 __cap_grew(permitted, ambient, new)))) 974 bprm->secureexec = 1; 975 976 return 0; 977 } 978 979 /** 980 * cap_inode_setxattr - Determine whether an xattr may be altered 981 * @dentry: The inode/dentry being altered 982 * @name: The name of the xattr to be changed 983 * @value: The value that the xattr will be changed to 984 * @size: The size of value 985 * @flags: The replacement flag 986 * 987 * Determine whether an xattr may be altered or set on an inode, returning 0 if 988 * permission is granted, -ve if denied. 989 * 990 * This is used to make sure security xattrs don't get updated or set by those 991 * who aren't privileged to do so. 992 */ 993 int cap_inode_setxattr(struct dentry *dentry, const char *name, 994 const void *value, size_t size, int flags) 995 { 996 struct user_namespace *user_ns = dentry->d_sb->s_user_ns; 997 998 /* Ignore non-security xattrs */ 999 if (strncmp(name, XATTR_SECURITY_PREFIX, 1000 XATTR_SECURITY_PREFIX_LEN) != 0) 1001 return 0; 1002 1003 /* 1004 * For XATTR_NAME_CAPS the check will be done in 1005 * cap_convert_nscap(), called by setxattr() 1006 */ 1007 if (strcmp(name, XATTR_NAME_CAPS) == 0) 1008 return 0; 1009 1010 if (!ns_capable(user_ns, CAP_SYS_ADMIN)) 1011 return -EPERM; 1012 return 0; 1013 } 1014 1015 /** 1016 * cap_inode_removexattr - Determine whether an xattr may be removed 1017 * 1018 * @mnt_userns: User namespace of the mount the inode was found from 1019 * @dentry: The inode/dentry being altered 1020 * @name: The name of the xattr to be changed 1021 * 1022 * Determine whether an xattr may be removed from an inode, returning 0 if 1023 * permission is granted, -ve if denied. 1024 * 1025 * If the inode has been found through an idmapped mount the user namespace of 1026 * the vfsmount must be passed through @mnt_userns. This function will then 1027 * take care to map the inode according to @mnt_userns before checking 1028 * permissions. On non-idmapped mounts or if permission checking is to be 1029 * performed on the raw inode simply passs init_user_ns. 1030 * 1031 * This is used to make sure security xattrs don't get removed by those who 1032 * aren't privileged to remove them. 1033 */ 1034 int cap_inode_removexattr(struct user_namespace *mnt_userns, 1035 struct dentry *dentry, const char *name) 1036 { 1037 struct user_namespace *user_ns = dentry->d_sb->s_user_ns; 1038 1039 /* Ignore non-security xattrs */ 1040 if (strncmp(name, XATTR_SECURITY_PREFIX, 1041 XATTR_SECURITY_PREFIX_LEN) != 0) 1042 return 0; 1043 1044 if (strcmp(name, XATTR_NAME_CAPS) == 0) { 1045 /* security.capability gets namespaced */ 1046 struct inode *inode = d_backing_inode(dentry); 1047 if (!inode) 1048 return -EINVAL; 1049 if (!capable_wrt_inode_uidgid(mnt_userns, inode, CAP_SETFCAP)) 1050 return -EPERM; 1051 return 0; 1052 } 1053 1054 if (!ns_capable(user_ns, CAP_SYS_ADMIN)) 1055 return -EPERM; 1056 return 0; 1057 } 1058 1059 /* 1060 * cap_emulate_setxuid() fixes the effective / permitted capabilities of 1061 * a process after a call to setuid, setreuid, or setresuid. 1062 * 1063 * 1) When set*uiding _from_ one of {r,e,s}uid == 0 _to_ all of 1064 * {r,e,s}uid != 0, the permitted and effective capabilities are 1065 * cleared. 1066 * 1067 * 2) When set*uiding _from_ euid == 0 _to_ euid != 0, the effective 1068 * capabilities of the process are cleared. 1069 * 1070 * 3) When set*uiding _from_ euid != 0 _to_ euid == 0, the effective 1071 * capabilities are set to the permitted capabilities. 1072 * 1073 * fsuid is handled elsewhere. fsuid == 0 and {r,e,s}uid!= 0 should 1074 * never happen. 1075 * 1076 * -astor 1077 * 1078 * cevans - New behaviour, Oct '99 1079 * A process may, via prctl(), elect to keep its capabilities when it 1080 * calls setuid() and switches away from uid==0. Both permitted and 1081 * effective sets will be retained. 1082 * Without this change, it was impossible for a daemon to drop only some 1083 * of its privilege. The call to setuid(!=0) would drop all privileges! 1084 * Keeping uid 0 is not an option because uid 0 owns too many vital 1085 * files.. 1086 * Thanks to Olaf Kirch and Peter Benie for spotting this. 1087 */ 1088 static inline void cap_emulate_setxuid(struct cred *new, const struct cred *old) 1089 { 1090 kuid_t root_uid = make_kuid(old->user_ns, 0); 1091 1092 if ((uid_eq(old->uid, root_uid) || 1093 uid_eq(old->euid, root_uid) || 1094 uid_eq(old->suid, root_uid)) && 1095 (!uid_eq(new->uid, root_uid) && 1096 !uid_eq(new->euid, root_uid) && 1097 !uid_eq(new->suid, root_uid))) { 1098 if (!issecure(SECURE_KEEP_CAPS)) { 1099 cap_clear(new->cap_permitted); 1100 cap_clear(new->cap_effective); 1101 } 1102 1103 /* 1104 * Pre-ambient programs expect setresuid to nonroot followed 1105 * by exec to drop capabilities. We should make sure that 1106 * this remains the case. 1107 */ 1108 cap_clear(new->cap_ambient); 1109 } 1110 if (uid_eq(old->euid, root_uid) && !uid_eq(new->euid, root_uid)) 1111 cap_clear(new->cap_effective); 1112 if (!uid_eq(old->euid, root_uid) && uid_eq(new->euid, root_uid)) 1113 new->cap_effective = new->cap_permitted; 1114 } 1115 1116 /** 1117 * cap_task_fix_setuid - Fix up the results of setuid() call 1118 * @new: The proposed credentials 1119 * @old: The current task's current credentials 1120 * @flags: Indications of what has changed 1121 * 1122 * Fix up the results of setuid() call before the credential changes are 1123 * actually applied. 1124 * 1125 * Return: 0 to grant the changes, -ve to deny them. 1126 */ 1127 int cap_task_fix_setuid(struct cred *new, const struct cred *old, int flags) 1128 { 1129 switch (flags) { 1130 case LSM_SETID_RE: 1131 case LSM_SETID_ID: 1132 case LSM_SETID_RES: 1133 /* juggle the capabilities to follow [RES]UID changes unless 1134 * otherwise suppressed */ 1135 if (!issecure(SECURE_NO_SETUID_FIXUP)) 1136 cap_emulate_setxuid(new, old); 1137 break; 1138 1139 case LSM_SETID_FS: 1140 /* juggle the capabilties to follow FSUID changes, unless 1141 * otherwise suppressed 1142 * 1143 * FIXME - is fsuser used for all CAP_FS_MASK capabilities? 1144 * if not, we might be a bit too harsh here. 1145 */ 1146 if (!issecure(SECURE_NO_SETUID_FIXUP)) { 1147 kuid_t root_uid = make_kuid(old->user_ns, 0); 1148 if (uid_eq(old->fsuid, root_uid) && !uid_eq(new->fsuid, root_uid)) 1149 new->cap_effective = 1150 cap_drop_fs_set(new->cap_effective); 1151 1152 if (!uid_eq(old->fsuid, root_uid) && uid_eq(new->fsuid, root_uid)) 1153 new->cap_effective = 1154 cap_raise_fs_set(new->cap_effective, 1155 new->cap_permitted); 1156 } 1157 break; 1158 1159 default: 1160 return -EINVAL; 1161 } 1162 1163 return 0; 1164 } 1165 1166 /* 1167 * Rationale: code calling task_setscheduler, task_setioprio, and 1168 * task_setnice, assumes that 1169 * . if capable(cap_sys_nice), then those actions should be allowed 1170 * . if not capable(cap_sys_nice), but acting on your own processes, 1171 * then those actions should be allowed 1172 * This is insufficient now since you can call code without suid, but 1173 * yet with increased caps. 1174 * So we check for increased caps on the target process. 1175 */ 1176 static int cap_safe_nice(struct task_struct *p) 1177 { 1178 int is_subset, ret = 0; 1179 1180 rcu_read_lock(); 1181 is_subset = cap_issubset(__task_cred(p)->cap_permitted, 1182 current_cred()->cap_permitted); 1183 if (!is_subset && !ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) 1184 ret = -EPERM; 1185 rcu_read_unlock(); 1186 1187 return ret; 1188 } 1189 1190 /** 1191 * cap_task_setscheduler - Detemine if scheduler policy change is permitted 1192 * @p: The task to affect 1193 * 1194 * Detemine if the requested scheduler policy change is permitted for the 1195 * specified task. 1196 * 1197 * Return: 0 if permission is granted, -ve if denied. 1198 */ 1199 int cap_task_setscheduler(struct task_struct *p) 1200 { 1201 return cap_safe_nice(p); 1202 } 1203 1204 /** 1205 * cap_task_setioprio - Detemine if I/O priority change is permitted 1206 * @p: The task to affect 1207 * @ioprio: The I/O priority to set 1208 * 1209 * Detemine if the requested I/O priority change is permitted for the specified 1210 * task. 1211 * 1212 * Return: 0 if permission is granted, -ve if denied. 1213 */ 1214 int cap_task_setioprio(struct task_struct *p, int ioprio) 1215 { 1216 return cap_safe_nice(p); 1217 } 1218 1219 /** 1220 * cap_task_setnice - Detemine if task priority change is permitted 1221 * @p: The task to affect 1222 * @nice: The nice value to set 1223 * 1224 * Detemine if the requested task priority change is permitted for the 1225 * specified task. 1226 * 1227 * Return: 0 if permission is granted, -ve if denied. 1228 */ 1229 int cap_task_setnice(struct task_struct *p, int nice) 1230 { 1231 return cap_safe_nice(p); 1232 } 1233 1234 /* 1235 * Implement PR_CAPBSET_DROP. Attempt to remove the specified capability from 1236 * the current task's bounding set. Returns 0 on success, -ve on error. 1237 */ 1238 static int cap_prctl_drop(unsigned long cap) 1239 { 1240 struct cred *new; 1241 1242 if (!ns_capable(current_user_ns(), CAP_SETPCAP)) 1243 return -EPERM; 1244 if (!cap_valid(cap)) 1245 return -EINVAL; 1246 1247 new = prepare_creds(); 1248 if (!new) 1249 return -ENOMEM; 1250 cap_lower(new->cap_bset, cap); 1251 return commit_creds(new); 1252 } 1253 1254 /** 1255 * cap_task_prctl - Implement process control functions for this security module 1256 * @option: The process control function requested 1257 * @arg2: The argument data for this function 1258 * @arg3: The argument data for this function 1259 * @arg4: The argument data for this function 1260 * @arg5: The argument data for this function 1261 * 1262 * Allow process control functions (sys_prctl()) to alter capabilities; may 1263 * also deny access to other functions not otherwise implemented here. 1264 * 1265 * Return: 0 or +ve on success, -ENOSYS if this function is not implemented 1266 * here, other -ve on error. If -ENOSYS is returned, sys_prctl() and other LSM 1267 * modules will consider performing the function. 1268 */ 1269 int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3, 1270 unsigned long arg4, unsigned long arg5) 1271 { 1272 const struct cred *old = current_cred(); 1273 struct cred *new; 1274 1275 switch (option) { 1276 case PR_CAPBSET_READ: 1277 if (!cap_valid(arg2)) 1278 return -EINVAL; 1279 return !!cap_raised(old->cap_bset, arg2); 1280 1281 case PR_CAPBSET_DROP: 1282 return cap_prctl_drop(arg2); 1283 1284 /* 1285 * The next four prctl's remain to assist with transitioning a 1286 * system from legacy UID=0 based privilege (when filesystem 1287 * capabilities are not in use) to a system using filesystem 1288 * capabilities only - as the POSIX.1e draft intended. 1289 * 1290 * Note: 1291 * 1292 * PR_SET_SECUREBITS = 1293 * issecure_mask(SECURE_KEEP_CAPS_LOCKED) 1294 * | issecure_mask(SECURE_NOROOT) 1295 * | issecure_mask(SECURE_NOROOT_LOCKED) 1296 * | issecure_mask(SECURE_NO_SETUID_FIXUP) 1297 * | issecure_mask(SECURE_NO_SETUID_FIXUP_LOCKED) 1298 * 1299 * will ensure that the current process and all of its 1300 * children will be locked into a pure 1301 * capability-based-privilege environment. 1302 */ 1303 case PR_SET_SECUREBITS: 1304 if ((((old->securebits & SECURE_ALL_LOCKS) >> 1) 1305 & (old->securebits ^ arg2)) /*[1]*/ 1306 || ((old->securebits & SECURE_ALL_LOCKS & ~arg2)) /*[2]*/ 1307 || (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS)) /*[3]*/ 1308 || (cap_capable(current_cred(), 1309 current_cred()->user_ns, 1310 CAP_SETPCAP, 1311 CAP_OPT_NONE) != 0) /*[4]*/ 1312 /* 1313 * [1] no changing of bits that are locked 1314 * [2] no unlocking of locks 1315 * [3] no setting of unsupported bits 1316 * [4] doing anything requires privilege (go read about 1317 * the "sendmail capabilities bug") 1318 */ 1319 ) 1320 /* cannot change a locked bit */ 1321 return -EPERM; 1322 1323 new = prepare_creds(); 1324 if (!new) 1325 return -ENOMEM; 1326 new->securebits = arg2; 1327 return commit_creds(new); 1328 1329 case PR_GET_SECUREBITS: 1330 return old->securebits; 1331 1332 case PR_GET_KEEPCAPS: 1333 return !!issecure(SECURE_KEEP_CAPS); 1334 1335 case PR_SET_KEEPCAPS: 1336 if (arg2 > 1) /* Note, we rely on arg2 being unsigned here */ 1337 return -EINVAL; 1338 if (issecure(SECURE_KEEP_CAPS_LOCKED)) 1339 return -EPERM; 1340 1341 new = prepare_creds(); 1342 if (!new) 1343 return -ENOMEM; 1344 if (arg2) 1345 new->securebits |= issecure_mask(SECURE_KEEP_CAPS); 1346 else 1347 new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS); 1348 return commit_creds(new); 1349 1350 case PR_CAP_AMBIENT: 1351 if (arg2 == PR_CAP_AMBIENT_CLEAR_ALL) { 1352 if (arg3 | arg4 | arg5) 1353 return -EINVAL; 1354 1355 new = prepare_creds(); 1356 if (!new) 1357 return -ENOMEM; 1358 cap_clear(new->cap_ambient); 1359 return commit_creds(new); 1360 } 1361 1362 if (((!cap_valid(arg3)) | arg4 | arg5)) 1363 return -EINVAL; 1364 1365 if (arg2 == PR_CAP_AMBIENT_IS_SET) { 1366 return !!cap_raised(current_cred()->cap_ambient, arg3); 1367 } else if (arg2 != PR_CAP_AMBIENT_RAISE && 1368 arg2 != PR_CAP_AMBIENT_LOWER) { 1369 return -EINVAL; 1370 } else { 1371 if (arg2 == PR_CAP_AMBIENT_RAISE && 1372 (!cap_raised(current_cred()->cap_permitted, arg3) || 1373 !cap_raised(current_cred()->cap_inheritable, 1374 arg3) || 1375 issecure(SECURE_NO_CAP_AMBIENT_RAISE))) 1376 return -EPERM; 1377 1378 new = prepare_creds(); 1379 if (!new) 1380 return -ENOMEM; 1381 if (arg2 == PR_CAP_AMBIENT_RAISE) 1382 cap_raise(new->cap_ambient, arg3); 1383 else 1384 cap_lower(new->cap_ambient, arg3); 1385 return commit_creds(new); 1386 } 1387 1388 default: 1389 /* No functionality available - continue with default */ 1390 return -ENOSYS; 1391 } 1392 } 1393 1394 /** 1395 * cap_vm_enough_memory - Determine whether a new virtual mapping is permitted 1396 * @mm: The VM space in which the new mapping is to be made 1397 * @pages: The size of the mapping 1398 * 1399 * Determine whether the allocation of a new virtual mapping by the current 1400 * task is permitted. 1401 * 1402 * Return: 1 if permission is granted, 0 if not. 1403 */ 1404 int cap_vm_enough_memory(struct mm_struct *mm, long pages) 1405 { 1406 int cap_sys_admin = 0; 1407 1408 if (cap_capable(current_cred(), &init_user_ns, 1409 CAP_SYS_ADMIN, CAP_OPT_NOAUDIT) == 0) 1410 cap_sys_admin = 1; 1411 1412 return cap_sys_admin; 1413 } 1414 1415 /** 1416 * cap_mmap_addr - check if able to map given addr 1417 * @addr: address attempting to be mapped 1418 * 1419 * If the process is attempting to map memory below dac_mmap_min_addr they need 1420 * CAP_SYS_RAWIO. The other parameters to this function are unused by the 1421 * capability security module. 1422 * 1423 * Return: 0 if this mapping should be allowed or -EPERM if not. 1424 */ 1425 int cap_mmap_addr(unsigned long addr) 1426 { 1427 int ret = 0; 1428 1429 if (addr < dac_mmap_min_addr) { 1430 ret = cap_capable(current_cred(), &init_user_ns, CAP_SYS_RAWIO, 1431 CAP_OPT_NONE); 1432 /* set PF_SUPERPRIV if it turns out we allow the low mmap */ 1433 if (ret == 0) 1434 current->flags |= PF_SUPERPRIV; 1435 } 1436 return ret; 1437 } 1438 1439 int cap_mmap_file(struct file *file, unsigned long reqprot, 1440 unsigned long prot, unsigned long flags) 1441 { 1442 return 0; 1443 } 1444 1445 #ifdef CONFIG_SECURITY 1446 1447 static struct security_hook_list capability_hooks[] __lsm_ro_after_init = { 1448 LSM_HOOK_INIT(capable, cap_capable), 1449 LSM_HOOK_INIT(settime, cap_settime), 1450 LSM_HOOK_INIT(ptrace_access_check, cap_ptrace_access_check), 1451 LSM_HOOK_INIT(ptrace_traceme, cap_ptrace_traceme), 1452 LSM_HOOK_INIT(capget, cap_capget), 1453 LSM_HOOK_INIT(capset, cap_capset), 1454 LSM_HOOK_INIT(bprm_creds_from_file, cap_bprm_creds_from_file), 1455 LSM_HOOK_INIT(inode_need_killpriv, cap_inode_need_killpriv), 1456 LSM_HOOK_INIT(inode_killpriv, cap_inode_killpriv), 1457 LSM_HOOK_INIT(inode_getsecurity, cap_inode_getsecurity), 1458 LSM_HOOK_INIT(mmap_addr, cap_mmap_addr), 1459 LSM_HOOK_INIT(mmap_file, cap_mmap_file), 1460 LSM_HOOK_INIT(task_fix_setuid, cap_task_fix_setuid), 1461 LSM_HOOK_INIT(task_prctl, cap_task_prctl), 1462 LSM_HOOK_INIT(task_setscheduler, cap_task_setscheduler), 1463 LSM_HOOK_INIT(task_setioprio, cap_task_setioprio), 1464 LSM_HOOK_INIT(task_setnice, cap_task_setnice), 1465 LSM_HOOK_INIT(vm_enough_memory, cap_vm_enough_memory), 1466 }; 1467 1468 static int __init capability_init(void) 1469 { 1470 security_add_hooks(capability_hooks, ARRAY_SIZE(capability_hooks), 1471 "capability"); 1472 return 0; 1473 } 1474 1475 DEFINE_LSM(capability) = { 1476 .name = "capability", 1477 .order = LSM_ORDER_FIRST, 1478 .init = capability_init, 1479 }; 1480 1481 #endif /* CONFIG_SECURITY */ 1482