4 * Copyright (c) 2011, 2012, 2013, 2015, 2016, Juniper Networks, Inc.
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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29 #include <sys/cdefs.h>
31 #include "opt_capsicum.h"
34 #include <sys/param.h>
35 #include <sys/systm.h>
36 #include <sys/capsicum.h>
37 #include <sys/eventhandler.h>
38 #include <sys/fcntl.h>
40 #include <sys/filedesc.h>
41 #include <sys/imgact.h>
43 #include <sys/kernel.h>
45 #include <sys/mount.h>
46 #include <sys/namei.h>
51 #include <sys/sysctl.h>
52 #include <sys/vnode.h>
53 #include <fs/nullfs/null.h>
54 #include <security/mac/mac_policy.h>
56 #include "mac_veriexec.h"
57 #include "mac_veriexec_internal.h"
60 mac_label_get((l), mac_veriexec_slot)
61 #define SLOT_SET(l, v) \
62 mac_label_set((l), mac_veriexec_slot, (v))
65 #define MAC_VERIEXEC_DBG(_lvl, _fmt, ...) \
67 VERIEXEC_DEBUG((_lvl), (MAC_VERIEXEC_FULLNAME ": " _fmt \
68 "\n", ##__VA_ARGS__)); \
71 #define MAC_VERIEXEC_DBG(_lvl, _fmt, ...)
74 static int sysctl_mac_veriexec_state(SYSCTL_HANDLER_ARGS);
75 static int sysctl_mac_veriexec_db(SYSCTL_HANDLER_ARGS);
77 SYSCTL_DECL(_security_mac);
79 SYSCTL_NODE(_security_mac, OID_AUTO, veriexec, CTLFLAG_RW, 0,
80 "MAC/veriexec policy controls");
82 int mac_veriexec_debug;
83 SYSCTL_INT(_security_mac_veriexec, OID_AUTO, debug, CTLFLAG_RW,
84 &mac_veriexec_debug, 0, "Debug level");
86 static int mac_veriexec_state;
87 SYSCTL_PROC(_security_mac_veriexec, OID_AUTO, state,
88 CTLTYPE_STRING | CTLFLAG_RD, 0, 0, sysctl_mac_veriexec_state, "A",
89 "Verified execution subsystem state");
91 SYSCTL_PROC(_security_mac_veriexec, OID_AUTO, db,
92 CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_SKIP, 0, 0, sysctl_mac_veriexec_db,
93 "A", "Verified execution fingerprint database");
95 static int mac_veriexec_slot;
97 MALLOC_DEFINE(M_VERIEXEC, "veriexec", "Verified execution data");
101 * @brief Handler for security.mac.veriexec.db sysctl
103 * Display a human-readable form of the current fingerprint database.
106 sysctl_mac_veriexec_db(SYSCTL_HANDLER_ARGS)
111 error = sysctl_wire_old_buffer(req, 0);
115 sbuf_new_for_sysctl(&sb, NULL, 1024, req);
116 mac_veriexec_metadata_print_db(&sb);
117 error = sbuf_finish(&sb);
125 * @brief Generate human-readable output about the current verified execution
128 * @param sbp sbuf to write output to
131 mac_veriexec_print_state(struct sbuf *sbp)
134 if (mac_veriexec_state & VERIEXEC_STATE_INACTIVE)
135 sbuf_printf(sbp, "inactive ");
136 if (mac_veriexec_state & VERIEXEC_STATE_LOADED)
137 sbuf_printf(sbp, "loaded ");
138 if (mac_veriexec_state & VERIEXEC_STATE_ACTIVE)
139 sbuf_printf(sbp, "active ");
140 if (mac_veriexec_state & VERIEXEC_STATE_ENFORCE)
141 sbuf_printf(sbp, "enforce ");
142 if (mac_veriexec_state & VERIEXEC_STATE_LOCKED)
143 sbuf_printf(sbp, "locked ");
144 if (mac_veriexec_state != 0)
150 * @brief Handler for security.mac.veriexec.state sysctl
152 * Display a human-readable form of the current verified execution subsystem
156 sysctl_mac_veriexec_state(SYSCTL_HANDLER_ARGS)
161 sbuf_new(&sb, NULL, 128, SBUF_AUTOEXTEND);
162 mac_veriexec_print_state(&sb);
165 error = SYSCTL_OUT(req, sbuf_data(&sb), sbuf_len(&sb));
172 * @brief Event handler called when a virtual file system is mounted.
174 * We need to record the file system identifier in the MAC per-policy slot
175 * assigned to veriexec, so we have a key to use in order to reference the
176 * mount point in the meta-data store.
178 * @param arg unused argument
179 * @param mp mount point that is being mounted
180 * @param fsrootvp vnode of the file system root
181 * @param td calling thread
184 mac_veriexec_vfs_mounted(void *arg __unused, struct mount *mp,
185 struct vnode *fsrootvp, struct thread *td)
190 error = VOP_GETATTR(fsrootvp, &va, td->td_ucred);
194 SLOT_SET(mp->mnt_label, va.va_fsid);
196 MAC_VERIEXEC_DBG(3, "set fsid to %u for mount %p", va.va_fsid, mp);
202 * @brief Event handler called when a virtual file system is unmounted.
204 * If we recorded a file system identifier in the MAC per-policy slot assigned
205 * to veriexec, then we need to tell the meta-data store to clean up.
207 * @param arg unused argument
208 * @param mp mount point that is being unmounted
209 * @param td calling thread
212 mac_veriexec_vfs_unmounted(void *arg __unused, struct mount *mp,
217 fsid = SLOT(mp->mnt_label);
219 MAC_VERIEXEC_DBG(3, "fsid %u, cleaning up mount", fsid);
220 mac_veriexec_metadata_unmounted(fsid, td);
226 * @brief The mount point is being initialized, set the value in the MAC
227 * per-policy slot for veriexec to zero.
229 * @note A value of zero in this slot indicates no file system identifier
232 * @param label the label that is being initialized
235 mac_veriexec_mount_init_label(struct label *label)
243 * @brief The mount-point is being destroyed, reset the value in the MAC
244 * per-policy slot for veriexec back to zero.
246 * @note A value of zero in this slot indicates no file system identifier
249 * @param label the label that is being destroyed
252 mac_veriexec_mount_destroy_label(struct label *label)
260 * @brief The vnode label is being initialized, set the value in the MAC
261 * per-policy slot for veriexec to @c FINGERPRINT_INVALID
263 * @note @c FINGERPRINT_INVALID indicates the fingerprint is invalid.
265 * @param label the label that is being initialized
268 mac_veriexec_vnode_init_label(struct label *label)
271 SLOT_SET(label, FINGERPRINT_INVALID);
276 * @brief The vnode label is being destroyed, reset the value in the MAC
277 * per-policy slot for veriexec back to @c FINGERPRINT_INVALID
279 * @note @c FINGERPRINT_INVALID indicates the fingerprint is invalid.
281 * @param label the label that is being destroyed
284 mac_veriexec_vnode_destroy_label(struct label *label)
287 SLOT_SET(label, FINGERPRINT_INVALID);
292 * @brief Copy the value in the MAC per-policy slot assigned to veriexec from
293 * the @p src label to the @p dest label
296 mac_veriexec_copy_label(struct label *src, struct label *dest)
299 SLOT_SET(dest, SLOT(src));
304 * @brief Check if the requested process can be debugged
306 * @param cred credentials to use
307 * @param p process to debug
309 * @return 0 if debugging is allowed, otherwise an error code.
312 mac_veriexec_proc_check_debug(struct ucred *cred, struct proc *p)
316 /* If we are not enforcing veriexec, nothing for us to check */
317 if ((mac_veriexec_state & VERIEXEC_STATE_ENFORCE) == 0)
320 error = mac_veriexec_metadata_get_executable_flags(cred, p, &flags, 0);
324 return ((flags & VERIEXEC_NOTRACE) ? EACCES : 0);
329 * @brief A KLD load has been requested and needs to be validated.
331 * @param cred credentials to use
332 * @param vp vnode of the KLD that has been requested
333 * @param vlabel vnode label assigned to the vnode
335 * @return 0 if the KLD load is allowed, otherwise an error code.
338 mac_veriexec_kld_check_load(struct ucred *cred, struct vnode *vp,
339 struct label *vlabel)
342 struct thread *td = curthread;
343 fingerprint_status_t status;
347 * If we are not actively enforcing, allow it
349 if ((mac_veriexec_state & VERIEXEC_STATE_ENFORCE) == 0)
352 /* Get vnode attributes */
353 error = VOP_GETATTR(vp, &va, cred);
358 * Fetch the fingerprint status for the vnode
359 * (starting with files first)
361 error = mac_veriexec_metadata_fetch_fingerprint_status(vp, &va, td,
362 VERIEXEC_FILES_FIRST);
363 if (error && error != EAUTH)
367 * By now we should have status...
369 status = mac_veriexec_get_fingerprint_status(vp);
371 case FINGERPRINT_FILE:
372 case FINGERPRINT_VALID:
373 case FINGERPRINT_INDIRECT:
379 * kldload should fail unless there is a valid fingerprint
382 MAC_VERIEXEC_DBG(2, "fingerprint status is %d for dev %u, "
383 "file %lu.%lu\n", status, va.va_fsid, va.va_fileid,
388 /* Everything is good, allow the KLD to be loaded */
394 * @brief Check privileges that veriexec needs to be concerned about.
396 * The following privileges are checked by this function:
397 * - PRIV_KMEM_WRITE\n
398 * Check if writes to /dev/mem and /dev/kmem are allowed\n
399 * (Only trusted processes are allowed)
401 * @param cred credentials to use
402 * @param priv privilege to check
404 * @return 0 if the privilege is allowed, error code otherwise.
407 mac_veriexec_priv_check(struct ucred *cred, int priv)
410 /* If we are not enforcing veriexec, nothing for us to check */
411 if ((mac_veriexec_state & VERIEXEC_STATE_ENFORCE) == 0)
415 case PRIV_KMEM_WRITE:
416 if (!mac_veriexec_proc_is_trusted(cred, curproc))
427 * @brief A program is being executed and needs to be validated.
429 * @param cred credentials to use
430 * @param vp vnode of the program that is being executed
431 * @param label vnode label assigned to the vnode
432 * @param imgp parameters for the image to be executed
433 * @param execlabel optional exec label
435 * @return 0 if the program should be allowed to execute, otherwise an error
439 mac_veriexec_vnode_check_exec(struct ucred *cred __unused,
440 struct vnode *vp __unused, struct label *label __unused,
441 struct image_params *imgp, struct label *execlabel __unused)
443 struct thread *td = curthread;
446 error = mac_veriexec_fingerprint_check_image(imgp, 0, td);
451 * @brief Check fingerprint for the specified vnode and validate it
453 * @param cred credentials to use
454 * @param vp vnode of the file
455 * @param accmode access mode to check (read, write, append, create,
458 * @return 0 if the file validated, otherwise an error code.
461 mac_veriexec_check_vp(struct ucred *cred, struct vnode *vp, accmode_t accmode)
464 struct thread *td = curthread;
465 fingerprint_status_t status;
468 /* Get vnode attributes */
469 error = VOP_GETATTR(vp, &va, cred);
473 /* Get the fingerprint status for the file */
474 error = mac_veriexec_metadata_fetch_fingerprint_status(vp, &va, td,
475 VERIEXEC_FILES_FIRST);
476 if (error && error != EAUTH)
480 * By now we should have status...
482 status = mac_veriexec_get_fingerprint_status(vp);
483 if (accmode & VWRITE) {
485 * If file has a fingerprint then deny the write request,
486 * otherwise invalidate the status so we don't keep checking
487 * for the file having a fingerprint.
490 case FINGERPRINT_FILE:
491 case FINGERPRINT_VALID:
492 case FINGERPRINT_INDIRECT:
494 "attempted write to fingerprinted file for dev "
495 "%u, file %lu.%lu\n", va.va_fsid,
496 va.va_fileid, va.va_gen);
502 if (accmode & VVERIFY) {
504 case FINGERPRINT_FILE:
505 case FINGERPRINT_VALID:
506 case FINGERPRINT_INDIRECT:
512 * Caller wants open to fail unless there is a valid
513 * fingerprint registered.
515 MAC_VERIEXEC_DBG(2, "fingerprint status is %d for dev "
516 "%u, file %lu.%lu\n", status, va.va_fsid,
517 va.va_fileid, va.va_gen);
525 * @brief Opening a file has been requested and may need to be validated.
527 * @param cred credentials to use
528 * @param vp vnode of the file to open
529 * @param label vnode label assigned to the vnode
530 * @param accmode access mode to use for opening the file (read, write,
531 * append, create, verify, etc.)
533 * @return 0 if opening the file should be allowed, otherwise an error code.
536 mac_veriexec_vnode_check_open(struct ucred *cred, struct vnode *vp,
537 struct label *label __unused, accmode_t accmode)
542 * Look for the file on the fingerprint lists iff it has not been seen
545 if ((mac_veriexec_state & VERIEXEC_STATE_ENFORCE) == 0)
548 error = mac_veriexec_check_vp(cred, vp, accmode);
553 * @brief Check mode changes on file to ensure they should be allowed.
555 * We cannot allow chmod of SUID or SGID on verified files.
557 * @param cred credentials to use
558 * @param vp vnode of the file to open
559 * @param label vnode label assigned to the vnode
560 * @param mode mode flags to set
562 * @return 0 if the mode change should be allowed, EAUTH otherwise.
565 mac_veriexec_vnode_check_setmode(struct ucred *cred, struct vnode *vp,
566 struct label *label __unused, mode_t mode)
570 if ((mac_veriexec_state & VERIEXEC_STATE_ENFORCE) == 0)
574 * Do not allow chmod (set-[gu]id) of verified file
576 error = mac_veriexec_check_vp(cred, vp, VVERIFY);
577 if (error == EAUTH) /* it isn't verified */
579 if (error == 0 && (mode & (S_ISUID|S_ISGID)) != 0)
586 * @brief Initialize the mac_veriexec MAC policy
588 * @param mpc MAC policy configuration
591 mac_veriexec_init(struct mac_policy_conf *mpc __unused)
593 /* Initialize state */
594 mac_veriexec_state = VERIEXEC_STATE_INACTIVE;
596 /* Initialize meta-data storage */
597 mac_veriexec_metadata_init();
599 /* Initialize fingerprint ops */
600 mac_veriexec_fingerprint_init();
602 /* Register event handlers */
603 EVENTHANDLER_REGISTER(vfs_mounted, mac_veriexec_vfs_mounted, NULL,
604 EVENTHANDLER_PRI_FIRST);
605 EVENTHANDLER_REGISTER(vfs_unmounted, mac_veriexec_vfs_unmounted, NULL,
606 EVENTHANDLER_PRI_LAST);
611 * @brief MAC policy-specific syscall for mac_veriexec
613 * The following syscalls are implemented:
614 * - @c MAC_VERIEXEC_CHECK_SYSCALL
615 * Check if the file referenced by a file descriptor has a fingerprint
616 * registered in the meta-data store.
618 * @param td calling thread
619 * @param call system call number
620 * @param arg arugments to the syscall
622 * @return 0 on success, otherwise an error code.
625 mac_veriexec_syscall(struct thread *td, int call, void *arg)
627 struct image_params img;
635 case MAC_VERIEXEC_CHECK_FD_SYSCALL:
636 /* Get the vnode associated with the file descriptor passed */
637 error = getvnode(td, (uintptr_t) arg, cap_rights_init(&rights,
641 if (fp->f_type != DTYPE_VNODE) {
642 MAC_VERIEXEC_DBG(3, "MAC_VERIEXEC_CHECK_SYSCALL: "
643 "file is not vnode type (type=0x%x)",
650 * setup the bits of image_params that are used by
651 * mac_veriexec_check_fingerprint().
653 bzero(&img, sizeof(img));
654 img.proc = td->td_proc;
655 img.vp = fp->f_vnode;
659 * Get vnode attributes
660 * (need to obtain a lock on the vnode first)
662 vn_lock(img.vp, LK_EXCLUSIVE | LK_RETRY);
663 error = VOP_GETATTR(fp->f_vnode, &va, td->td_ucred);
667 MAC_VERIEXEC_DBG(2, "mac_veriexec_fingerprint_check_image: "
668 "va_mode=%o, check_files=%d\n", va.va_mode,
669 ((va.va_mode & (S_IXUSR|S_IXGRP|S_IXOTH)) == 0));
670 error = mac_veriexec_fingerprint_check_image(&img,
671 ((va.va_mode & (S_IXUSR|S_IXGRP|S_IXOTH)) == 0), td);
673 /* Release the lock we obtained earlier */
674 VOP_UNLOCK(img.vp, 0);
678 case MAC_VERIEXEC_CHECK_PATH_SYSCALL:
679 /* Look up the path to get the vnode */
680 NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | AUDITVNODE1,
681 UIO_USERSPACE, arg, td);
685 NDFREE(&nd, NDF_ONLY_PNBUF);
687 /* Check the fingerprint status of the vnode */
688 error = mac_veriexec_check_vp(td->td_ucred, nd.ni_vp, VVERIFY);
697 static struct mac_policy_ops mac_veriexec_ops =
699 .mpo_init = mac_veriexec_init,
700 .mpo_syscall = mac_veriexec_syscall,
701 .mpo_kld_check_load = mac_veriexec_kld_check_load,
702 .mpo_mount_destroy_label = mac_veriexec_mount_destroy_label,
703 .mpo_mount_init_label = mac_veriexec_mount_init_label,
704 .mpo_priv_check = mac_veriexec_priv_check,
705 .mpo_proc_check_debug = mac_veriexec_proc_check_debug,
706 .mpo_vnode_check_exec = mac_veriexec_vnode_check_exec,
707 .mpo_vnode_check_open = mac_veriexec_vnode_check_open,
708 .mpo_vnode_check_setmode = mac_veriexec_vnode_check_setmode,
709 .mpo_vnode_copy_label = mac_veriexec_copy_label,
710 .mpo_vnode_destroy_label = mac_veriexec_vnode_destroy_label,
711 .mpo_vnode_init_label = mac_veriexec_vnode_init_label,
714 MAC_POLICY_SET(&mac_veriexec_ops, mac_veriexec, MAC_VERIEXEC_FULLNAME,
715 MPC_LOADTIME_FLAG_NOTLATE, &mac_veriexec_slot);
716 MODULE_VERSION(mac_veriexec, 1);
719 * @brief Get the fingerprint status set on a vnode.
721 * @param vp vnode to obtain fingerprint status from
723 * @return Fingerprint status assigned to the vnode.
726 mac_veriexec_get_fingerprint_status(struct vnode *vp)
728 fingerprint_status_t fps;
730 fps = SLOT(vp->v_label);
732 case FINGERPRINT_VALID:
733 case FINGERPRINT_INDIRECT:
734 case FINGERPRINT_FILE:
737 /* we may need to recurse */
738 if (strcmp(vp->v_tag, "null") == 0) {
741 ldvp = NULLVPTOLOWERVP(vp);
742 return mac_veriexec_get_fingerprint_status(ldvp);
750 * @brief Get the current verified execution subsystem state.
752 * @return Current set of verified execution subsystem state flags.
755 mac_veriexec_get_state(void)
758 return (mac_veriexec_state);
762 * @brief Determine if the verified execution subsystem state has specific
765 * @param state mask of flags to check
767 * @return State flags set within the masked bits
770 mac_veriexec_in_state(int state)
773 return (mac_veriexec_state & state);
777 * @brief Set the fingerprint status for a vnode
779 * Fingerprint status is stored in the MAC per-policy slot assigned to
782 * @param vp vnode to store the fingerprint status on
783 * @param fp_status fingerprint status to store
786 mac_veriexec_set_fingerprint_status(struct vnode *vp,
787 fingerprint_status_t fp_status)
790 /* recurse until we find the real storage */
791 if (strcmp(vp->v_tag, "null") == 0) {
794 ldvp = NULLVPTOLOWERVP(vp);
795 mac_veriexec_set_fingerprint_status(ldvp, fp_status);
798 SLOT_SET(vp->v_label, fp_status);
802 * @brief Set verified execution subsystem state flags
804 * @note Flags can only be added to the current state, not removed.
806 * @param state state flags to add to the current state
809 mac_veriexec_set_state(int state)
812 mac_veriexec_state |= state;
816 * @brief Determine if the process is trusted
818 * @param cred credentials to use
819 * @param p the process in question
821 * @return 1 if the process is trusted, otherwise 0.
824 mac_veriexec_proc_is_trusted(struct ucred *cred, struct proc *p)
828 error = mac_veriexec_metadata_get_executable_flags(cred, p, &flags, 0);
830 /* Any errors, deny access */
834 /* Check that the trusted flag is set */
835 return ((flags & VERIEXEC_TRUSTED) == VERIEXEC_TRUSTED);