4 * Copyright (c) 2011, 2012, 2013, 2015, 2016, 2019 Juniper Networks, Inc.
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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 | CTLFLAG_MPSAFE, 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 | CTLFLAG_NEEDGIANT,
89 0, 0, sysctl_mac_veriexec_state, "A",
90 "Verified execution subsystem state");
92 SYSCTL_PROC(_security_mac_veriexec, OID_AUTO, db,
93 CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_SKIP | CTLFLAG_NEEDGIANT,
94 0, 0, sysctl_mac_veriexec_db,
95 "A", "Verified execution fingerprint database");
97 static int mac_veriexec_slot;
99 MALLOC_DEFINE(M_VERIEXEC, "veriexec", "Verified execution data");
103 * @brief Handler for security.mac.veriexec.db sysctl
105 * Display a human-readable form of the current fingerprint database.
108 sysctl_mac_veriexec_db(SYSCTL_HANDLER_ARGS)
113 error = sysctl_wire_old_buffer(req, 0);
117 sbuf_new_for_sysctl(&sb, NULL, 1024, req);
118 mac_veriexec_metadata_print_db(&sb);
119 error = sbuf_finish(&sb);
127 * @brief Generate human-readable output about the current verified execution
130 * @param sbp sbuf to write output to
133 mac_veriexec_print_state(struct sbuf *sbp)
136 if (mac_veriexec_state & VERIEXEC_STATE_INACTIVE)
137 sbuf_printf(sbp, "inactive ");
138 if (mac_veriexec_state & VERIEXEC_STATE_LOADED)
139 sbuf_printf(sbp, "loaded ");
140 if (mac_veriexec_state & VERIEXEC_STATE_ACTIVE)
141 sbuf_printf(sbp, "active ");
142 if (mac_veriexec_state & VERIEXEC_STATE_ENFORCE)
143 sbuf_printf(sbp, "enforce ");
144 if (mac_veriexec_state & VERIEXEC_STATE_LOCKED)
145 sbuf_printf(sbp, "locked ");
146 if (mac_veriexec_state != 0)
152 * @brief Handler for security.mac.veriexec.state sysctl
154 * Display a human-readable form of the current verified execution subsystem
158 sysctl_mac_veriexec_state(SYSCTL_HANDLER_ARGS)
163 sbuf_new(&sb, NULL, 128, SBUF_AUTOEXTEND);
164 mac_veriexec_print_state(&sb);
167 error = SYSCTL_OUT(req, sbuf_data(&sb), sbuf_len(&sb));
174 * @brief Event handler called when a virtual file system is mounted.
176 * We need to record the file system identifier in the MAC per-policy slot
177 * assigned to veriexec, so we have a key to use in order to reference the
178 * mount point in the meta-data store.
180 * @param arg unused argument
181 * @param mp mount point that is being mounted
182 * @param fsrootvp vnode of the file system root
183 * @param td calling thread
186 mac_veriexec_vfs_mounted(void *arg __unused, struct mount *mp,
187 struct vnode *fsrootvp, struct thread *td)
192 error = VOP_GETATTR(fsrootvp, &va, td->td_ucred);
196 SLOT_SET(mp->mnt_label, va.va_fsid);
198 MAC_VERIEXEC_DBG(3, "set fsid to %ju for mount %p",
199 (uintmax_t)va.va_fsid, mp);
205 * @brief Event handler called when a virtual file system is unmounted.
207 * If we recorded a file system identifier in the MAC per-policy slot assigned
208 * to veriexec, then we need to tell the meta-data store to clean up.
210 * @param arg unused argument
211 * @param mp mount point that is being unmounted
212 * @param td calling thread
215 mac_veriexec_vfs_unmounted(void *arg __unused, struct mount *mp,
220 fsid = SLOT(mp->mnt_label);
222 MAC_VERIEXEC_DBG(3, "fsid %ju, cleaning up mount",
224 mac_veriexec_metadata_unmounted(fsid, td);
230 * @brief The mount point is being initialized, set the value in the MAC
231 * per-policy slot for veriexec to zero.
233 * @note A value of zero in this slot indicates no file system identifier
236 * @param label the label that is being initialized
239 mac_veriexec_mount_init_label(struct label *label)
247 * @brief The mount-point is being destroyed, reset the value in the MAC
248 * per-policy slot for veriexec back to zero.
250 * @note A value of zero in this slot indicates no file system identifier
253 * @param label the label that is being destroyed
256 mac_veriexec_mount_destroy_label(struct label *label)
264 * @brief The vnode label is being initialized, set the value in the MAC
265 * per-policy slot for veriexec to @c FINGERPRINT_INVALID
267 * @note @c FINGERPRINT_INVALID indicates the fingerprint is invalid.
269 * @param label the label that is being initialized
272 mac_veriexec_vnode_init_label(struct label *label)
275 SLOT_SET(label, FINGERPRINT_INVALID);
280 * @brief The vnode label is being destroyed, reset the value in the MAC
281 * per-policy slot for veriexec back to @c FINGERPRINT_INVALID
283 * @note @c FINGERPRINT_INVALID indicates the fingerprint is invalid.
285 * @param label the label that is being destroyed
288 mac_veriexec_vnode_destroy_label(struct label *label)
291 SLOT_SET(label, FINGERPRINT_INVALID);
296 * @brief Copy the value in the MAC per-policy slot assigned to veriexec from
297 * the @p src label to the @p dest label
300 mac_veriexec_copy_label(struct label *src, struct label *dest)
303 SLOT_SET(dest, SLOT(src));
308 * @brief Check if the requested process can be debugged
310 * @param cred credentials to use
311 * @param p process to debug
313 * @return 0 if debugging is allowed, otherwise an error code.
316 mac_veriexec_proc_check_debug(struct ucred *cred, struct proc *p)
320 /* If we are not enforcing veriexec, nothing for us to check */
321 if ((mac_veriexec_state & VERIEXEC_STATE_ENFORCE) == 0)
324 error = mac_veriexec_metadata_get_executable_flags(cred, p, &flags, 0);
328 return ((flags & VERIEXEC_NOTRACE) ? EACCES : 0);
333 * @brief A KLD load has been requested and needs to be validated.
335 * @param cred credentials to use
336 * @param vp vnode of the KLD that has been requested
337 * @param vlabel vnode label assigned to the vnode
339 * @return 0 if the KLD load is allowed, otherwise an error code.
342 mac_veriexec_kld_check_load(struct ucred *cred, struct vnode *vp,
343 struct label *vlabel)
346 struct thread *td = curthread;
347 fingerprint_status_t status;
351 * If we are not actively enforcing, allow it
353 if ((mac_veriexec_state & VERIEXEC_STATE_ENFORCE) == 0)
356 /* Get vnode attributes */
357 error = VOP_GETATTR(vp, &va, cred);
362 * Fetch the fingerprint status for the vnode
363 * (starting with files first)
365 error = mac_veriexec_metadata_fetch_fingerprint_status(vp, &va, td,
366 VERIEXEC_FILES_FIRST);
367 if (error && error != EAUTH)
371 * By now we should have status...
373 status = mac_veriexec_get_fingerprint_status(vp);
375 case FINGERPRINT_FILE:
376 case FINGERPRINT_VALID:
377 case FINGERPRINT_INDIRECT:
383 * kldload should fail unless there is a valid fingerprint
386 MAC_VERIEXEC_DBG(2, "fingerprint status is %d for dev %ju, "
387 "file %ju.%ju\n", status, (uintmax_t)va.va_fsid,
388 (uintmax_t)va.va_fileid, (uintmax_t)va.va_gen);
392 /* Everything is good, allow the KLD to be loaded */
398 * @brief Check privileges that veriexec needs to be concerned about.
400 * The following privileges are checked by this function:
401 * - PRIV_KMEM_WRITE\n
402 * Check if writes to /dev/mem and /dev/kmem are allowed\n
403 * (Only trusted processes are allowed)
405 * @param cred credentials to use
406 * @param priv privilege to check
408 * @return 0 if the privilege is allowed, error code otherwise.
411 mac_veriexec_priv_check(struct ucred *cred, int priv)
414 /* If we are not enforcing veriexec, nothing for us to check */
415 if ((mac_veriexec_state & VERIEXEC_STATE_ENFORCE) == 0)
419 case PRIV_KMEM_WRITE:
420 if (!mac_veriexec_proc_is_trusted(cred, curproc))
430 mac_veriexec_sysctl_check(struct ucred *cred, struct sysctl_oid *oidp,
431 void *arg1, int arg2, struct sysctl_req *req)
433 struct sysctl_oid *oid;
435 /* If we are not enforcing veriexec, nothing for us to check */
436 if ((mac_veriexec_state & VERIEXEC_STATE_ENFORCE) == 0)
440 if (oid->oid_kind & CTLFLAG_SECURE) {
441 return (EPERM); /* XXX call mac_veriexec_priv_check? */
448 * @brief A program is being executed and needs to be validated.
450 * @param cred credentials to use
451 * @param vp vnode of the program that is being executed
452 * @param label vnode label assigned to the vnode
453 * @param imgp parameters for the image to be executed
454 * @param execlabel optional exec label
456 * @return 0 if the program should be allowed to execute, otherwise an error
460 mac_veriexec_vnode_check_exec(struct ucred *cred __unused,
461 struct vnode *vp __unused, struct label *label __unused,
462 struct image_params *imgp, struct label *execlabel __unused)
464 struct thread *td = curthread;
467 error = mac_veriexec_fingerprint_check_image(imgp, 0, td);
472 * @brief Check fingerprint for the specified vnode and validate it
474 * @param cred credentials to use
475 * @param vp vnode of the file
476 * @param accmode access mode to check (read, write, append, create,
479 * @return 0 if the file validated, otherwise an error code.
482 mac_veriexec_check_vp(struct ucred *cred, struct vnode *vp, accmode_t accmode)
485 struct thread *td = curthread;
486 fingerprint_status_t status;
489 /* Get vnode attributes */
490 error = VOP_GETATTR(vp, &va, cred);
494 /* Get the fingerprint status for the file */
495 error = mac_veriexec_metadata_fetch_fingerprint_status(vp, &va, td,
496 VERIEXEC_FILES_FIRST);
497 if (error && error != EAUTH)
501 * By now we should have status...
503 status = mac_veriexec_get_fingerprint_status(vp);
504 if (accmode & VWRITE) {
506 * If file has a fingerprint then deny the write request,
507 * otherwise invalidate the status so we don't keep checking
508 * for the file having a fingerprint.
511 case FINGERPRINT_FILE:
512 case FINGERPRINT_VALID:
513 case FINGERPRINT_INDIRECT:
515 "attempted write to fingerprinted file for dev "
516 "%ju, file %ju.%ju\n", (uintmax_t)va.va_fsid,
517 (uintmax_t)va.va_fileid, (uintmax_t)va.va_gen);
523 if (accmode & VVERIFY) {
525 case FINGERPRINT_FILE:
526 case FINGERPRINT_VALID:
527 case FINGERPRINT_INDIRECT:
533 * Caller wants open to fail unless there is a valid
534 * fingerprint registered.
536 MAC_VERIEXEC_DBG(2, "fingerprint status is %d for dev "
537 "%ju, file %ju.%ju\n", status,
538 (uintmax_t)va.va_fsid, (uintmax_t)va.va_fileid,
539 (uintmax_t)va.va_gen);
547 * @brief Opening a file has been requested and may need to be validated.
549 * @param cred credentials to use
550 * @param vp vnode of the file to open
551 * @param label vnode label assigned to the vnode
552 * @param accmode access mode to use for opening the file (read, write,
553 * append, create, verify, etc.)
555 * @return 0 if opening the file should be allowed, otherwise an error code.
558 mac_veriexec_vnode_check_open(struct ucred *cred, struct vnode *vp,
559 struct label *label __unused, accmode_t accmode)
564 * Look for the file on the fingerprint lists iff it has not been seen
567 if ((mac_veriexec_state & VERIEXEC_STATE_ENFORCE) == 0)
570 error = mac_veriexec_check_vp(cred, vp, accmode);
575 * @brief Check mode changes on file to ensure they should be allowed.
577 * We cannot allow chmod of SUID or SGID on verified files.
579 * @param cred credentials to use
580 * @param vp vnode of the file to open
581 * @param label vnode label assigned to the vnode
582 * @param mode mode flags to set
584 * @return 0 if the mode change should be allowed, EAUTH otherwise.
587 mac_veriexec_vnode_check_setmode(struct ucred *cred, struct vnode *vp,
588 struct label *label __unused, mode_t mode)
592 if ((mac_veriexec_state & VERIEXEC_STATE_ENFORCE) == 0)
596 * Do not allow chmod (set-[gu]id) of verified file
598 error = mac_veriexec_check_vp(cred, vp, VVERIFY);
599 if (error == EAUTH) /* it isn't verified */
601 if (error == 0 && (mode & (S_ISUID|S_ISGID)) != 0)
608 * @brief Initialize the mac_veriexec MAC policy
610 * @param mpc MAC policy configuration
613 mac_veriexec_init(struct mac_policy_conf *mpc __unused)
615 /* Initialize state */
616 mac_veriexec_state = VERIEXEC_STATE_INACTIVE;
618 /* Initialize meta-data storage */
619 mac_veriexec_metadata_init();
621 /* Initialize fingerprint ops */
622 mac_veriexec_fingerprint_init();
624 /* Register event handlers */
625 EVENTHANDLER_REGISTER(vfs_mounted, mac_veriexec_vfs_mounted, NULL,
626 EVENTHANDLER_PRI_FIRST);
627 EVENTHANDLER_REGISTER(vfs_unmounted, mac_veriexec_vfs_unmounted, NULL,
628 EVENTHANDLER_PRI_LAST);
633 * @brief MAC policy-specific syscall for mac_veriexec
635 * The following syscalls are implemented:
636 * - @c MAC_VERIEXEC_CHECK_SYSCALL
637 * Check if the file referenced by a file descriptor has a fingerprint
638 * registered in the meta-data store.
640 * @param td calling thread
641 * @param call system call number
642 * @param arg arugments to the syscall
644 * @return 0 on success, otherwise an error code.
647 mac_veriexec_syscall(struct thread *td, int call, void *arg)
649 struct image_params img;
657 case MAC_VERIEXEC_CHECK_FD_SYSCALL:
658 /* Get the vnode associated with the file descriptor passed */
659 error = getvnode(td, (uintptr_t) arg, cap_rights_init(&rights,
663 if (fp->f_type != DTYPE_VNODE) {
664 MAC_VERIEXEC_DBG(3, "MAC_VERIEXEC_CHECK_SYSCALL: "
665 "file is not vnode type (type=0x%x)",
672 * setup the bits of image_params that are used by
673 * mac_veriexec_check_fingerprint().
675 bzero(&img, sizeof(img));
676 img.proc = td->td_proc;
677 img.vp = fp->f_vnode;
681 * Get vnode attributes
682 * (need to obtain a lock on the vnode first)
684 vn_lock(img.vp, LK_EXCLUSIVE | LK_RETRY);
685 error = VOP_GETATTR(fp->f_vnode, &va, td->td_ucred);
689 MAC_VERIEXEC_DBG(2, "mac_veriexec_fingerprint_check_image: "
690 "va_mode=%o, check_files=%d\n", va.va_mode,
691 ((va.va_mode & (S_IXUSR|S_IXGRP|S_IXOTH)) == 0));
692 error = mac_veriexec_fingerprint_check_image(&img,
693 ((va.va_mode & (S_IXUSR|S_IXGRP|S_IXOTH)) == 0), td);
695 /* Release the lock we obtained earlier */
700 case MAC_VERIEXEC_CHECK_PATH_SYSCALL:
701 /* Look up the path to get the vnode */
703 FOLLOW | LOCKLEAF | LOCKSHARED | AUDITVNODE1,
704 UIO_USERSPACE, arg, td);
708 NDFREE(&nd, NDF_ONLY_PNBUF);
710 /* Check the fingerprint status of the vnode */
711 error = mac_veriexec_check_vp(td->td_ucred, nd.ni_vp, VVERIFY);
720 static struct mac_policy_ops mac_veriexec_ops =
722 .mpo_init = mac_veriexec_init,
723 .mpo_kld_check_load = mac_veriexec_kld_check_load,
724 .mpo_mount_destroy_label = mac_veriexec_mount_destroy_label,
725 .mpo_mount_init_label = mac_veriexec_mount_init_label,
726 .mpo_priv_check = mac_veriexec_priv_check,
727 .mpo_proc_check_debug = mac_veriexec_proc_check_debug,
728 .mpo_syscall = mac_veriexec_syscall,
729 .mpo_system_check_sysctl = mac_veriexec_sysctl_check,
730 .mpo_vnode_check_exec = mac_veriexec_vnode_check_exec,
731 .mpo_vnode_check_open = mac_veriexec_vnode_check_open,
732 .mpo_vnode_check_setmode = mac_veriexec_vnode_check_setmode,
733 .mpo_vnode_copy_label = mac_veriexec_copy_label,
734 .mpo_vnode_destroy_label = mac_veriexec_vnode_destroy_label,
735 .mpo_vnode_init_label = mac_veriexec_vnode_init_label,
738 MAC_POLICY_SET(&mac_veriexec_ops, mac_veriexec, MAC_VERIEXEC_FULLNAME,
739 MPC_LOADTIME_FLAG_NOTLATE, &mac_veriexec_slot);
740 MODULE_VERSION(mac_veriexec, 1);
742 static struct vnode *
743 mac_veriexec_bottom_vnode(struct vnode *vp)
745 struct vnode *ldvp = NULL;
748 * XXX This code is bogus. nullfs is not the only stacking
749 * filesystem. Less bogus code would add a VOP to reach bottom
750 * vnode and would not make assumptions how to get there.
752 if (vp->v_mount != NULL &&
753 strcmp(vp->v_mount->mnt_vfc->vfc_name, "nullfs") == 0)
754 ldvp = NULLVPTOLOWERVP(vp);
759 * @brief Get the fingerprint status set on a vnode.
761 * @param vp vnode to obtain fingerprint status from
763 * @return Fingerprint status assigned to the vnode.
766 mac_veriexec_get_fingerprint_status(struct vnode *vp)
768 fingerprint_status_t fps;
771 fps = SLOT(vp->v_label);
773 case FINGERPRINT_VALID:
774 case FINGERPRINT_INDIRECT:
775 case FINGERPRINT_FILE:
778 /* we may need to recurse */
779 ldvp = mac_veriexec_bottom_vnode(vp);
781 return mac_veriexec_get_fingerprint_status(ldvp);
788 * @brief Get the current verified execution subsystem state.
790 * @return Current set of verified execution subsystem state flags.
793 mac_veriexec_get_state(void)
796 return (mac_veriexec_state);
800 * @brief Determine if the verified execution subsystem state has specific
803 * @param state mask of flags to check
805 * @return State flags set within the masked bits
808 mac_veriexec_in_state(int state)
811 return (mac_veriexec_state & state);
815 * @brief Set the fingerprint status for a vnode
817 * Fingerprint status is stored in the MAC per-policy slot assigned to
820 * @param vp vnode to store the fingerprint status on
821 * @param fp_status fingerprint status to store
824 mac_veriexec_set_fingerprint_status(struct vnode *vp,
825 fingerprint_status_t fp_status)
829 /* recurse until we find the real storage */
830 ldvp = mac_veriexec_bottom_vnode(vp);
832 mac_veriexec_set_fingerprint_status(ldvp, fp_status);
835 SLOT_SET(vp->v_label, fp_status);
839 * @brief Set verified execution subsystem state flags
841 * @note Flags can only be added to the current state, not removed.
843 * @param state state flags to add to the current state
846 mac_veriexec_set_state(int state)
849 mac_veriexec_state |= state;
853 * @brief Determine if the process is trusted
855 * @param cred credentials to use
856 * @param p the process in question
858 * @return 1 if the process is trusted, otherwise 0.
861 mac_veriexec_proc_is_trusted(struct ucred *cred, struct proc *p)
863 int already_locked, error, flags;
865 /* Make sure we lock the process if we do not already have the lock */
866 already_locked = PROC_LOCKED(p);
870 error = mac_veriexec_metadata_get_executable_flags(cred, p, &flags, 0);
872 /* Unlock the process if we locked it previously */
876 /* Any errors, deny access */
880 /* Check that the trusted flag is set */
881 return ((flags & VERIEXEC_TRUSTED) == VERIEXEC_TRUSTED);