/* * * Copyright (c) 2011, 2012, 2013, 2015, 2016, 2019, Juniper Networks, Inc. * All rights reserved. * * Originally derived from: * $NetBSD: kern_verifiedexec.c,v 1.7 2003/11/18 13:13:03 martin Exp $ * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #include #include "opt_mac.h" #include #include #include #include #include #include #include #include #include #include "mac_veriexec.h" #include "mac_veriexec_internal.h" /** * @brief per-device meta-data storage */ struct veriexec_dev_list { dev_t fsid; /**< file system identifier of the mount point */ LIST_HEAD(filehead, mac_veriexec_file_info) file_head; /**< list of per-file meta-data information */ LIST_ENTRY(veriexec_dev_list) entries; /**< next entries in the device list */ }; typedef LIST_HEAD(veriexec_devhead, veriexec_dev_list) veriexec_devhead_t; /** * @brief Mutex to protect the meta-data store lists */ struct mtx ve_mutex; /** * @brief Executables meta-data storage * * This is used to store the fingerprints for potentially-executable files. */ veriexec_devhead_t veriexec_dev_head; /** * @brief Plain file meta-data storage * * This is used for files that are not allowed to be executed, but should * have fingerprint validation available. */ veriexec_devhead_t veriexec_file_dev_head; /** * @internal * @brief Search the @p head meta-data list for the specified file identifier * @p fileid in the file system identified by @p fsid * * If meta-data exists for file system identified by @p fsid, it has a * fingerprint list, and @p found_dev is not @c NULL then store true in the * location pointed to by @p found_dev * * @param head meta-data list to search * @param fsid file system identifier to look for * @param fileid file to look for * @param gen generation of file * @param found_dev indicator that an entry for the file system was found * * @return A pointer to the meta-data inforation if meta-data exists for * the specified file identifier, otherwise @c NULL */ static struct mac_veriexec_file_info * get_veriexec_file(struct veriexec_devhead *head, dev_t fsid, long fileid, unsigned long gen, int *found_dev) { struct veriexec_dev_list *lp; struct mac_veriexec_file_info *ip, *tip; ip = NULL; /* Initialize the value found_dev, if non-NULL */ if (found_dev != NULL) *found_dev = 0; VERIEXEC_DEBUG(3, ("searching for file %ju.%lu on device %ju," " files=%d\n", (uintmax_t)fileid, gen, (uintmax_t)fsid, (head == &veriexec_file_dev_head))); /* Get a lock to access the list */ mtx_lock(&ve_mutex); /* First, look for the file system */ for (lp = LIST_FIRST(head); lp != NULL; lp = LIST_NEXT(lp, entries)) if (lp->fsid == fsid) break; /* We found the file system in the list */ if (lp != NULL) { VERIEXEC_DEBUG(3, ("found matching dev number %ju\n", (uintmax_t)lp->fsid)); /* If found_dev is non-NULL, store true there */ if (found_dev != NULL) *found_dev = 1; /* Next, look for the meta-data information for the file */ LIST_FOREACH_SAFE(ip, &(lp->file_head), entries, tip) { if (ip->fileid == fileid) { if (ip->gen == gen) break; /* we need to garbage collect */ LIST_REMOVE(ip, entries); if (ip->label) free(ip->label, M_VERIEXEC); free(ip, M_VERIEXEC); } } } /* Release the lock we obtained earlier */ mtx_unlock(&ve_mutex); /* Return the meta-data information we found, if anything */ return (ip); } /** * @internal * @brief Display the fingerprint for each entry in the device list * * @param sbp sbuf to write output to * @param lp pointer to device list */ static void mac_veriexec_print_db_dev_list(struct sbuf *sbp, struct veriexec_dev_list *lp) { struct mac_veriexec_file_info *ip; #define FPB(i) (ip->fingerprint[i]) for (ip = LIST_FIRST(&(lp->file_head)); ip != NULL; ip = LIST_NEXT(ip, entries)) sbuf_printf(sbp, " %ld: %u %ld [%02x %02x %02x %02x %02x " "%02x %02x %02x...]\n", ip->fileid, ip->flags, ip->gen, FPB(0), FPB(1), FPB(2), FPB(3), FPB(4), FPB(5), FPB(6), FPB(7)); } /** * @internal * @brief Display the device list * * @param sbp sbuf to write output to * @param head pointer to head of the device list */ static void mac_veriexec_print_db_head(struct sbuf *sbp, struct veriexec_devhead *head) { struct veriexec_dev_list *lp; for (lp = LIST_FIRST(head); lp != NULL; lp = LIST_NEXT(lp, entries)) { sbuf_printf(sbp, " FS id: %ju\n", (uintmax_t)lp->fsid); mac_veriexec_print_db_dev_list(sbp, lp); } } /** * @internal * @brief Generate human-readable output for the current fingerprint database * * @param sbp sbuf to write output to */ void mac_veriexec_metadata_print_db(struct sbuf *sbp) { struct { struct veriexec_devhead *h; const char *name; } fpdbs[] = { { &veriexec_file_dev_head, "regular files" }, { &veriexec_dev_head, "executable files" }, }; int i; mtx_lock(&ve_mutex); for (i = 0; i < sizeof(fpdbs)/sizeof(fpdbs[0]); i++) { sbuf_printf(sbp, "%s fingerprint db:\n", fpdbs[i].name); mac_veriexec_print_db_head(sbp, fpdbs[i].h); } mtx_unlock(&ve_mutex); } /** * @brief Determine if the meta-data store has an entry for the specified file. * * @param fsid file system identifier to look for * @param fileid file to look for * @param gen generation of file * * @return 1 if there is an entry in the meta-data store, 0 otherwise. */ int mac_veriexec_metadata_has_file(dev_t fsid, long fileid, unsigned long gen) { return (mac_veriexec_metadata_get_file_info(fsid, fileid, gen, NULL, VERIEXEC_FILES_FIRST) != NULL); } /** * @brief Search the list of devices looking for the one given, in order to * release the resources used by it. * * If found, free all file entries for it, and remove it from the list. * * @note Called with @a ve_mutex held * * @param fsid file system identifier to look for * @param head meta-data list to search * * @return 0 if the device entry was freed, otherwise an error code */ static int free_veriexec_dev(dev_t fsid, struct veriexec_devhead *head) { struct veriexec_dev_list *lp; struct mac_veriexec_file_info *ip, *nip; /* Look for the file system */ for (lp = LIST_FIRST(head); lp != NULL; lp = LIST_NEXT(lp, entries)) if (lp->fsid == fsid) break; /* If lp is NULL, we did not find it */ if (lp == NULL) return ENOENT; /* Unhook lp, before we free it and its content */ LIST_REMOVE(lp, entries); /* Release the lock */ mtx_unlock(&ve_mutex); /* Free the file entries in the list */ for (ip = LIST_FIRST(&(lp->file_head)); ip != NULL; ip = nip) { nip = LIST_NEXT(ip, entries); LIST_REMOVE(ip, entries); if (ip->label) free(ip->label, M_VERIEXEC); free(ip, M_VERIEXEC); } /* Free the meta-data entry for the device */ free(lp, M_VERIEXEC); /* Re-acquire the lock */ mtx_lock(&ve_mutex); return 0; } /** * @brief Search the list of devices looking for the one given. * * If it is not in the list then add it. * * @note Called with @a ve_mutex held * * @param fsid file system identifier to look for * @param head meta-data list to search * * @return A pointer to the meta-data entry for the device, if found or added, * otherwise @c NULL */ static struct veriexec_dev_list * find_veriexec_dev(dev_t fsid, struct veriexec_devhead *head) { struct veriexec_dev_list *lp; struct veriexec_dev_list *np = NULL; search: /* Look for the file system */ for (lp = LIST_FIRST(head); lp != NULL; lp = LIST_NEXT(lp, entries)) if (lp->fsid == fsid) break; if (lp == NULL) { if (np == NULL) { /* * If pointer is null then entry not there, * add a new one, first try to malloc while * we hold mutex - should work most of the time. */ np = malloc(sizeof(struct veriexec_dev_list), M_VERIEXEC, M_NOWAIT); if (np == NULL) { /* * So much for that plan, dop the mutex * and repeat... */ mtx_unlock(&ve_mutex); np = malloc(sizeof(struct veriexec_dev_list), M_VERIEXEC, M_WAITOK); mtx_lock(&ve_mutex); /* * Repeat the search, in case someone * added this while we slept. */ goto search; } } if (np) { /* Add the entry to the list */ lp = np; LIST_INIT(&(lp->file_head)); lp->fsid = fsid; LIST_INSERT_HEAD(head, lp, entries); } } else if (np) { /* * Someone else did it while we slept. */ mtx_unlock(&ve_mutex); free(np, M_VERIEXEC); mtx_lock(&ve_mutex); } return (lp); } /** * @internal * @brief Allocate and initialize label record with the provided data. * * @param labelp Location to store the initialized label * @param src Pointer to label string to copy * @param srclen Length of label string to copy * * @return Length of resulting label * * @note Called with ve_mutex locked. */ static size_t mac_veriexec_init_label(char **labelp, size_t labellen, char *src, size_t srclen) { char *label; label = *labelp; if (labellen < srclen) { mtx_unlock(&ve_mutex); if (label != NULL) free(label, M_VERIEXEC); label = malloc(srclen, M_VERIEXEC, M_WAITOK); mtx_lock(&ve_mutex); labellen = srclen; *labelp = label; } memcpy(label, src, srclen); return labellen; } /** * @brief When a device is unmounted, we want to toss the signatures recorded * against it. * * We are being called from unmount() with the root vnode just before it is * freed. * * @param fsid file system identifier to look for * @param td calling thread * * @return 0 on success, otherwise an error code. */ int mac_veriexec_metadata_unmounted(dev_t fsid, struct thread *td) { int error; /* * The device can have entries on both lists. */ mtx_lock(&ve_mutex); error = free_veriexec_dev(fsid, &veriexec_dev_head); if (error && error != ENOENT) { mtx_unlock(&ve_mutex); return error; } error = free_veriexec_dev(fsid, &veriexec_file_dev_head); mtx_unlock(&ve_mutex); if (error && error != ENOENT) { return error; } return 0; } /** * @brief Return the flags assigned to the file identified by file system * identifier @p fsid and file identifier @p fileid. * * @param fsid file system identifier * @param fileid file identifier within the file system * @param gen generation of file * @param flags pointer to location to store the flags * @param check_files if 1, check the files list first, otherwise check the * exectuables list first * * @return 0 on success, otherwise an error code. */ int mac_veriexec_metadata_get_file_flags(dev_t fsid, long fileid, unsigned long gen, int *flags, int check_files) { struct mac_veriexec_file_info *ip; int found_dev; ip = mac_veriexec_metadata_get_file_info(fsid, fileid, gen, &found_dev, check_files); if (ip == NULL) return (ENOENT); *flags = ip->flags; return (0); } /** * @brief get the files for the specified process * * @param cred credentials to use * @param p process to get the flags for * @param flags where to store the flags * @param check_files if 1, check the files list first, otherwise check the * exectuables list first * * @return 0 if the process has an entry in the meta-data store, otherwise an * error code */ int mac_veriexec_metadata_get_executable_flags(struct ucred *cred, struct proc *p, int *flags, int check_files) { struct vnode *proc_vn; struct vattr vap; int error; /* Get the text vnode for the process */ proc_vn = p->p_textvp; if (proc_vn == NULL) return EINVAL; /* Get vnode attributes */ error = VOP_GETATTR(proc_vn, &vap, cred); if (error) return error; error = mac_veriexec_metadata_get_file_flags(vap.va_fsid, vap.va_fileid, vap.va_gen, flags, (check_files == VERIEXEC_FILES_FIRST)); return (error); } /** * @brief Ensure the fingerprint status for the vnode @p vp is assigned to its * MAC label. * * @param vp vnode to check * @param vap vnode attributes to use * @param td calling thread * @param check_files if 1, check the files list first, otherwise check the * exectuables list first * * @return 0 on success, otherwise an error code. */ int mac_veriexec_metadata_fetch_fingerprint_status(struct vnode *vp, struct vattr *vap, struct thread *td, int check_files) { unsigned char digest[MAXFINGERPRINTLEN]; struct mac_veriexec_file_info *ip; int error, found_dev; fingerprint_status_t status; error = 0; ip = NULL; status = mac_veriexec_get_fingerprint_status(vp); if (status == FINGERPRINT_INVALID || status == FINGERPRINT_NODEV) { found_dev = 0; ip = mac_veriexec_metadata_get_file_info(vap->va_fsid, vap->va_fileid, vap->va_gen, &found_dev, check_files); if (ip == NULL) { status = (found_dev) ? FINGERPRINT_NOENTRY : FINGERPRINT_NODEV; VERIEXEC_DEBUG(3, ("fingerprint status is %d for dev %ju, file " "%ju.%lu\n", status, (uintmax_t)vap->va_fsid, (uintmax_t)vap->va_fileid, vap->va_gen)); } else { /* * evaluate and compare fingerprint */ error = mac_veriexec_fingerprint_check_vnode(vp, ip, td, vap->va_size, digest); switch (error) { case 0: /* Process flags */ if ((ip->flags & VERIEXEC_INDIRECT)) status = FINGERPRINT_INDIRECT; else if ((ip->flags & VERIEXEC_FILE)) status = FINGERPRINT_FILE; else status = FINGERPRINT_VALID; VERIEXEC_DEBUG(2, ("%sfingerprint matches for dev %ju, file " "%ju.%lu\n", (status == FINGERPRINT_INDIRECT) ? "indirect " : (status == FINGERPRINT_FILE) ? "file " : "", (uintmax_t)vap->va_fsid, (uintmax_t)vap->va_fileid, vap->va_gen)); break; case EAUTH: #ifdef VERIFIED_EXEC_DEBUG_VERBOSE { char have[MAXFINGERPRINTLEN * 2 + 1]; char want[MAXFINGERPRINTLEN * 2 + 1]; int i, len; len = ip->ops->digest_len; for (i = 0; i < len; i++) { sprintf(&want[i * 2], "%02x", ip->fingerprint[i]); sprintf(&have[i * 2], "%02x", digest[i]); } log(LOG_ERR, MAC_VERIEXEC_FULLNAME ": fingerprint for dev %ju, file " "%ju.%lu %s != %s\n", (uintmax_t)vap->va_fsid, (uintmax_t)vap->va_fileid, vap->va_gen, have, want); } #endif status = FINGERPRINT_NOMATCH; break; default: VERIEXEC_DEBUG(2, ("fingerprint status error %d\n", error)); break; } } mac_veriexec_set_fingerprint_status(vp, status); } return (error); } /** * Add a file and its fingerprint to the list of files attached * to the device @p fsid. * * Only add the entry if it is not already on the list. * * @note Called with @a ve_mutex held * * @param file_dev if 1, the entry should be added on the file list, * otherwise it should be added on the executable list * @param fsid file system identifier of device * @param fileid file to add * @param gen generation of file * @param fingerprint fingerprint to add to the store * @param flags flags to set in the store * @param fp_type digest type * @param override if 1, override any values already stored * * @return 0 on success, otherwise an error code. */ int mac_veriexec_metadata_add_file(int file_dev, dev_t fsid, long fileid, unsigned long gen, unsigned char fingerprint[MAXFINGERPRINTLEN], char *label, size_t labellen, int flags, const char *fp_type, int override) { struct mac_veriexec_fpops *fpops; struct veriexec_dev_list *lp; struct veriexec_devhead *head; struct mac_veriexec_file_info *ip; struct mac_veriexec_file_info *np = NULL; /* Label and labellen must be set if VERIEXEC_LABEL is set */ if ((flags & VERIEXEC_LABEL) != 0 && (label == NULL || labellen == 0)) return (EINVAL); /* Look up the device entry */ if (file_dev) head = &veriexec_file_dev_head; else head = &veriexec_dev_head; lp = find_veriexec_dev(fsid, head); /* Look up the fingerprint operations for the digest type */ fpops = mac_veriexec_fingerprint_lookup_ops(fp_type); if (fpops == NULL) return (EOPNOTSUPP); search: for (ip = LIST_FIRST(&(lp->file_head)); ip != NULL; ip = LIST_NEXT(ip, entries)) { /* check for a dupe file in the list, skip if an entry * exists for this file except for when the flags contains * VERIEXEC_INDIRECT, always set the flags when it is so * we don't get a hole caused by conflicting flags on * hardlinked files. XXX maybe we should validate * fingerprint is same and complain if it is not... */ if (ip->fileid == fileid && ip->gen == gen) { if (override) { /* * for a signed load we allow overrides, * otherwise fingerpints needed for pkg loads * can fail (the files are on temp device). */ ip->flags = flags; ip->ops = fpops; memcpy(ip->fingerprint, fingerprint, fpops->digest_len); if (flags & VERIEXEC_LABEL) { ip->labellen = mac_veriexec_init_label( &ip->label, ip->labellen, label, labellen); } else if (ip->labellen > 0) { free(ip->label, M_VERIEXEC); ip->labellen = 0; ip->label = NULL; } } else if ((flags & (VERIEXEC_INDIRECT|VERIEXEC_FILE))) ip->flags |= flags; if (np) { /* unlikely but... we don't need it now. */ mtx_unlock(&ve_mutex); free(np, M_VERIEXEC); mtx_lock(&ve_mutex); } return (0); } } /* * We may have been past here before... */ if (np == NULL) { /* * We first try with mutex held and nowait. */ np = malloc(sizeof(struct mac_veriexec_file_info), M_VERIEXEC, M_NOWAIT); if (np == NULL) { /* * It was worth a try, now * drop mutex while we malloc. */ mtx_unlock(&ve_mutex); np = malloc(sizeof(struct mac_veriexec_file_info), M_VERIEXEC, M_WAITOK); mtx_lock(&ve_mutex); /* * We now have to repeat our search! */ goto search; } } /* Set up the meta-data entry */ ip = np; ip->flags = flags; ip->ops = fpops; ip->fileid = fileid; ip->gen = gen; memcpy(ip->fingerprint, fingerprint, fpops->digest_len); if (flags & VERIEXEC_LABEL) ip->labellen = mac_veriexec_init_label(&ip->label, ip->labellen, label, labellen); else { ip->label = NULL; ip->labellen = 0; } VERIEXEC_DEBUG(3, ("add file %ju.%lu (files=%d)\n", (uintmax_t)ip->fileid, ip->gen, file_dev)); /* Add the entry to the list */ LIST_INSERT_HEAD(&(lp->file_head), ip, entries); #ifdef DEBUG_VERIEXEC_FINGERPRINT { off_t offset; printf("Stored %s fingerprint:\n", fp_type); for (offset = 0; offset < fpops->digest_len; offset++) printf("%02x", fingerprint[offset]); printf("\n"); } #endif return (0); } /** * @brief Search the meta-data store for information on the specified file. * * @param fsid file system identifier to look for * @param fileid file to look for * @param gen generation of file * @param found_dev indicator that an entry for the file system was found * @param check_files if 1, check the files list first, otherwise check the * exectuables list first * * @return A pointer to the meta-data inforation if meta-data exists for * the specified file identifier, otherwise @c NULL */ struct mac_veriexec_file_info * mac_veriexec_metadata_get_file_info(dev_t fsid, long fileid, unsigned long gen, int *found_dev, int check_files) { struct veriexec_devhead *search[3]; struct mac_veriexec_file_info *ip; int x; /* Determine the order of the lists to search */ if (check_files) { search[0] = &veriexec_file_dev_head; search[1] = &veriexec_dev_head; } else { search[0] = &veriexec_dev_head; search[1] = &veriexec_file_dev_head; } search[2] = NULL; VERIEXEC_DEBUG(3, ("%s: searching for dev %ju, file %lu\n", __func__, (uintmax_t)fsid, fileid)); /* Search for the specified file */ for (ip = NULL, x = 0; ip == NULL && search[x]; x++) ip = get_veriexec_file(search[x], fsid, fileid, gen, found_dev); return (ip); } /** * @brief Intialize the meta-data store */ void mac_veriexec_metadata_init(void) { mtx_init(&ve_mutex, "veriexec lock", NULL, MTX_DEF); LIST_INIT(&veriexec_dev_head); LIST_INIT(&veriexec_file_dev_head); }