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NetBSD/sys/kern/kern_verifiedexec.c

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/* $NetBSD: kern_verifiedexec.c,v 1.95 2007/02/06 01:09:48 elad Exp $ */
/*-
* Copyright (c) 2005, 2006 Elad Efrat <elad@NetBSD.org>
* Copyright (c) 2005, 2006 Brett Lymn <blymn@NetBSD.org>
* All rights reserved.
*
* 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.
* 3. The name of the authors may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``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 AUTHORS 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 <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: kern_verifiedexec.c,v 1.95 2007/02/06 01:09:48 elad Exp $");
#include "opt_veriexec.h"
#include <sys/param.h>
#include <sys/mount.h>
#include <sys/malloc.h>
#include <sys/vnode.h>
#include <sys/namei.h>
#include <sys/exec.h>
#include <sys/once.h>
#include <sys/proc.h>
#include <sys/syslog.h>
#include <sys/sysctl.h>
#include <sys/inttypes.h>
#include <sys/verified_exec.h>
#if defined(__FreeBSD__)
# include <sys/systm.h>
# include <sys/imgact.h>
# include <crypto/sha1.h>
# include <crypto/sha2/sha2.h>
# include <crypto/ripemd160/rmd160.h>
#else
# include <sys/sha1.h>
# include <sys/sha2.h>
# include <sys/rmd160.h>
#endif
#include <sys/md5.h>
#include <uvm/uvm_extern.h>
#include <sys/fileassoc.h>
#include <sys/kauth.h>
#include <sys/conf.h>
#include <miscfs/specfs/specdev.h>
#include <prop/proplib.h>
#include <sys/fcntl.h>
MALLOC_DEFINE(M_VERIEXEC, "Veriexec", "Veriexec data-structures");
struct veriexec_fpops {
const char *type;
size_t hash_len;
size_t context_size;
veriexec_fpop_init_t init;
veriexec_fpop_update_t update;
veriexec_fpop_final_t final;
LIST_ENTRY(veriexec_fpops) entries;
};
/* Veriexec per-file entry data. */
struct veriexec_file_entry {
u_char type; /* Entry type. */
u_char status; /* Evaluation status. */
u_char page_fp_status; /* Per-page FP status. */
u_char *fp; /* Fingerprint. */
void *page_fp; /* Per-page fingerprints */
size_t npages; /* Number of pages. */
size_t last_page_size; /* To support < PAGE_SIZE */
struct veriexec_fpops *ops; /* Fingerprint ops vector*/
};
/* Veriexec per-table data. */
struct veriexec_table_entry {
uint64_t vte_count; /* Number of Veriexec entries. */
const struct sysctlnode *vte_node;
};
static int veriexec_verbose;
int veriexec_strict;
static char *veriexec_fp_names;
static size_t veriexec_name_max;
static const struct sysctlnode *veriexec_count_node;
static fileassoc_t veriexec_hook;
static specificdata_key_t veriexec_mountspecific_key;
static LIST_HEAD(, veriexec_fpops) veriexec_fpops_list;
static int veriexec_raw_cb(kauth_cred_t, kauth_action_t, void *,
void *, void *, void *, void *);
static int sysctl_kern_veriexec(SYSCTLFN_PROTO);
static struct veriexec_fpops *veriexec_fpops_lookup(const char *);
static void veriexec_clear(void *);
static unsigned int veriexec_tablecount = 0;
/*
* Sysctl helper routine for Veriexec.
*/
static int
sysctl_kern_veriexec(SYSCTLFN_ARGS)
{
int newval, error;
int *var = NULL, raise_only = 0;
struct sysctlnode node;
node = *rnode;
if (strcmp(rnode->sysctl_name, "strict") == 0) {
raise_only = 1;
var = &veriexec_strict;
} else if (strcmp(rnode->sysctl_name, "algorithms") == 0) {
node.sysctl_data = veriexec_fp_names;
node.sysctl_size = strlen(veriexec_fp_names) + 1;
return (sysctl_lookup(SYSCTLFN_CALL(&node)));
} else {
return (EINVAL);
}
newval = *var;
node.sysctl_data = &newval;
error = sysctl_lookup(SYSCTLFN_CALL(&node));
if (error || newp == NULL) {
return (error);
}
if (raise_only && (newval < *var))
return (EPERM);
*var = newval;
return (error);
}
SYSCTL_SETUP(sysctl_kern_veriexec_setup, "sysctl kern.veriexec setup")
{
const struct sysctlnode *rnode = NULL;
sysctl_createv(clog, 0, NULL, &rnode,
CTLFLAG_PERMANENT,
CTLTYPE_NODE, "kern", NULL,
NULL, 0, NULL, 0,
CTL_KERN, CTL_EOL);
sysctl_createv(clog, 0, &rnode, &rnode,
CTLFLAG_PERMANENT,
CTLTYPE_NODE, "veriexec",
SYSCTL_DESCR("Veriexec"),
NULL, 0, NULL, 0,
CTL_CREATE, CTL_EOL);
sysctl_createv(clog, 0, &rnode, NULL,
CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
CTLTYPE_INT, "verbose",
SYSCTL_DESCR("Veriexec verbose level"),
NULL, 0, &veriexec_verbose, 0,
CTL_CREATE, CTL_EOL);
sysctl_createv(clog, 0, &rnode, NULL,
CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
CTLTYPE_INT, "strict",
SYSCTL_DESCR("Veriexec strict level"),
sysctl_kern_veriexec, 0, NULL, 0,
CTL_CREATE, CTL_EOL);
sysctl_createv(clog, 0, &rnode, NULL,
CTLFLAG_PERMANENT,
CTLTYPE_STRING, "algorithms",
SYSCTL_DESCR("Veriexec supported hashing "
"algorithms"),
sysctl_kern_veriexec, 0, NULL, 0,
CTL_CREATE, CTL_EOL);
sysctl_createv(clog, 0, &rnode, &veriexec_count_node,
CTLFLAG_PERMANENT,
CTLTYPE_NODE, "count",
SYSCTL_DESCR("Number of fingerprints on mount(s)"),
NULL, 0, NULL, 0,
CTL_CREATE, CTL_EOL);
}
/*
* Add ops to the fignerprint ops vector list.
*/
int
veriexec_fpops_add(const char *fp_type, size_t hash_len, size_t ctx_size,
veriexec_fpop_init_t init, veriexec_fpop_update_t update,
veriexec_fpop_final_t final)
{
struct veriexec_fpops *ops;
char *newp;
unsigned int new_max;
/* Sanity check all parameters. */
if ((fp_type == NULL) || (hash_len == 0) || (ctx_size == 0) ||
(init == NULL) || (update == NULL) || (final == NULL))
return (EFAULT);
if (veriexec_fpops_lookup(fp_type) != NULL)
return (EEXIST);
ops = malloc(sizeof(*ops), M_VERIEXEC, M_WAITOK);
ops->type = fp_type;
ops->hash_len = hash_len;
ops->context_size = ctx_size;
ops->init = init;
ops->update = update;
ops->final = final;
LIST_INSERT_HEAD(&veriexec_fpops_list, ops, entries);
/*
* If we don't have space for any names, allocate enough for six
* which should be sufficient. (it's also enough for all algorithms
* we can support at the moment)
*/
if (veriexec_fp_names == NULL) {
veriexec_name_max = 64;
veriexec_fp_names = malloc(veriexec_name_max, M_VERIEXEC,
M_WAITOK|M_ZERO);
}
/*
* If we're running out of space for storing supported algorithms,
* extend the buffer with space for four names.
*/
while (veriexec_name_max - (strlen(veriexec_fp_names) + 1) <
strlen(fp_type)) {
/* Add space for four algorithm names. */
new_max = veriexec_name_max + 64;
newp = realloc(veriexec_fp_names, new_max, M_VERIEXEC,
M_WAITOK|M_ZERO);
veriexec_fp_names = newp;
veriexec_name_max = new_max;
}
if (*veriexec_fp_names != '\0')
strlcat(veriexec_fp_names, " ", veriexec_name_max);
strlcat(veriexec_fp_names, fp_type, veriexec_name_max);
return (0);
}
/*
* Initialise Veriexec.
*/
void
veriexec_init(void)
{
int error;
/* Register a fileassoc for Veriexec. */
error = fileassoc_register("veriexec", veriexec_clear, &veriexec_hook);
if (error != 0)
panic("Veriexec: Can't register fileassoc: error=%d", error);
/* Register listener to handle raw disk access. */
if (kauth_listen_scope(KAUTH_SCOPE_DEVICE, veriexec_raw_cb, NULL) ==
NULL)
panic("Veriexec: Can't listen on device scope");
LIST_INIT(&veriexec_fpops_list);
veriexec_fp_names = NULL;
veriexec_name_max = 0;
#define FPOPS_ADD(a, b, c, d, e, f) \
veriexec_fpops_add(a, b, c, (veriexec_fpop_init_t)d, \
(veriexec_fpop_update_t)e, (veriexec_fpop_final_t)f)
#ifdef VERIFIED_EXEC_FP_RMD160
FPOPS_ADD("RMD160", RMD160_DIGEST_LENGTH, sizeof(RMD160_CTX),
RMD160Init, RMD160Update, RMD160Final);
#endif /* VERIFIED_EXEC_FP_RMD160 */
#ifdef VERIFIED_EXEC_FP_SHA256
FPOPS_ADD("SHA256", SHA256_DIGEST_LENGTH, sizeof(SHA256_CTX),
SHA256_Init, SHA256_Update, SHA256_Final);
#endif /* VERIFIED_EXEC_FP_SHA256 */
#ifdef VERIFIED_EXEC_FP_SHA384
FPOPS_ADD("SHA384", SHA384_DIGEST_LENGTH, sizeof(SHA384_CTX),
SHA384_Init, SHA384_Update, SHA384_Final);
#endif /* VERIFIED_EXEC_FP_SHA384 */
#ifdef VERIFIED_EXEC_FP_SHA512
FPOPS_ADD("SHA512", SHA512_DIGEST_LENGTH, sizeof(SHA512_CTX),
SHA512_Init, SHA512_Update, SHA512_Final);
#endif /* VERIFIED_EXEC_FP_SHA512 */
#ifdef VERIFIED_EXEC_FP_SHA1
FPOPS_ADD("SHA1", SHA1_DIGEST_LENGTH, sizeof(SHA1_CTX),
SHA1Init, SHA1Update, SHA1Final);
#endif /* VERIFIED_EXEC_FP_SHA1 */
#ifdef VERIFIED_EXEC_FP_MD5
FPOPS_ADD("MD5", MD5_DIGEST_LENGTH, sizeof(MD5_CTX),
MD5Init, MD5Update, MD5Final);
#endif /* VERIFIED_EXEC_FP_MD5 */
#undef FPOPS_ADD
}
static void
veriexec_mountspecific_dtor(void *vp)
{
struct veriexec_table_entry *vte = vp;
if (vte == NULL) {
return;
}
sysctl_free(__UNCONST(vte->vte_node));
veriexec_tablecount--;
free(vte, M_VERIEXEC);
}
static int
veriexec_mountspecific_init(void)
{
int error;
error = mount_specific_key_create(&veriexec_mountspecific_key,
veriexec_mountspecific_dtor);
return error;
}
static struct veriexec_fpops *
veriexec_fpops_lookup(const char *name)
{
struct veriexec_fpops *ops;
if (name == NULL)
return (NULL);
LIST_FOREACH(ops, &veriexec_fpops_list, entries) {
if (strcasecmp(name, ops->type) == 0)
return (ops);
}
return (NULL);
}
/*
* Calculate fingerprint. Information on hash length and routines used is
* extracted from veriexec_hash_list according to the hash type.
*/
static int
veriexec_fp_calc(struct lwp *l, struct vnode *vp,
struct veriexec_file_entry *vfe, u_char *fp)
{
struct vattr va;
void *ctx, *page_ctx;
u_char *buf, *page_fp;
off_t offset, len;
size_t resid, npages;
int error, do_perpage, pagen;
error = VOP_GETATTR(vp, &va, l->l_cred, l);
if (error)
return (error);
#ifdef notyet /* XXX - for now */
if ((vfe->type & VERIEXEC_UNTRUSTED) &&
(vfe->page_fp_status == PAGE_FP_NONE))
do_perpage = 1;
else
#endif /* notyet */
do_perpage = 0;
ctx = (void *) malloc(vfe->ops->context_size, M_VERIEXEC, M_WAITOK);
buf = (u_char *) malloc(PAGE_SIZE, M_VERIEXEC, M_WAITOK);
page_ctx = NULL;
page_fp = NULL;
npages = 0;
if (do_perpage) {
npages = (va.va_size >> PAGE_SHIFT) + 1;
page_fp = (u_char *) malloc(vfe->ops->hash_len * npages,
M_VERIEXEC, M_WAITOK|M_ZERO);
vfe->page_fp = page_fp;
page_ctx = (void *) malloc(vfe->ops->context_size, M_VERIEXEC,
M_WAITOK);
}
(vfe->ops->init)(ctx);
len = 0;
error = 0;
pagen = 0;
for (offset = 0; offset < va.va_size; offset += PAGE_SIZE) {
len = ((va.va_size - offset) < PAGE_SIZE) ?
(va.va_size - offset) : PAGE_SIZE;
error = vn_rdwr(UIO_READ, vp, buf, len, offset,
UIO_SYSSPACE,
#ifdef __FreeBSD__
IO_NODELOCKED,
#else
0,
#endif
l->l_cred, &resid, NULL);
if (error) {
if (do_perpage) {
free(vfe->page_fp, M_VERIEXEC);
vfe->page_fp = NULL;
}
goto bad;
}
(vfe->ops->update)(ctx, buf, (unsigned int) len);
if (do_perpage) {
(vfe->ops->init)(page_ctx);
(vfe->ops->update)(page_ctx, buf, (unsigned int)len);
(vfe->ops->final)(page_fp, page_ctx);
if (veriexec_verbose >= 2) {
int i;
printf("hash for page %d: ", pagen);
for (i = 0; i < vfe->ops->hash_len; i++)
printf("%02x", page_fp[i]);
printf("\n");
}
page_fp += vfe->ops->hash_len;
pagen++;
}
if (len != PAGE_SIZE)
break;
}
(vfe->ops->final)(fp, ctx);
if (do_perpage) {
vfe->last_page_size = len;
vfe->page_fp_status = PAGE_FP_READY;
vfe->npages = npages;
}
bad:
if (do_perpage)
free(page_ctx, M_VERIEXEC);
free(ctx, M_VERIEXEC);
free(buf, M_VERIEXEC);
return (error);
}
/* Compare two fingerprints of the same type. */
static int
veriexec_fp_cmp(struct veriexec_fpops *ops, u_char *fp1, u_char *fp2)
{
if (veriexec_verbose >= 2) {
int i;
printf("comparing hashes...\n");
printf("fp1: ");
for (i = 0; i < ops->hash_len; i++) {
printf("%02x", fp1[i]);
}
printf("\nfp2: ");
for (i = 0; i < ops->hash_len; i++) {
printf("%02x", fp2[i]);
}
printf("\n");
}
return (memcmp(fp1, fp2, ops->hash_len));
}
static struct veriexec_table_entry *
veriexec_table_lookup(struct mount *mp)
{
/* XXX: From raidframe init */
if (mp == NULL)
return NULL;
return mount_getspecific(mp, veriexec_mountspecific_key);
}
static struct veriexec_file_entry *
veriexec_get(struct vnode *vp)
{
return (fileassoc_lookup(vp, veriexec_hook));
}
boolean_t
veriexec_lookup(struct vnode *vp)
{
return (veriexec_get(vp) == NULL ? FALSE : TRUE);
}
/*
* Verify the fingerprint of the given file. If we're called directly from
* sys_execve(), 'flag' will be VERIEXEC_DIRECT. If we're called from
* exec_script(), 'flag' will be VERIEXEC_INDIRECT. If we are called from
* vn_open(), 'flag' will be VERIEXEC_FILE.
*/
int
veriexec_verify(struct lwp *l, struct vnode *vp, const u_char *name, int flag,
boolean_t *found)
{
struct veriexec_file_entry *vfe;
u_char *digest;
int error;
if (vp->v_type != VREG)
return (0);
/* Lookup veriexec table entry, save pointer if requested. */
vfe = veriexec_get(vp);
if (found != NULL) {
if (vfe != NULL)
*found = TRUE;
else
*found = FALSE;
}
if (vfe == NULL)
goto out;
/* Evaluate fingerprint if needed. */
error = 0;
digest = NULL;
if ((vfe->status == FINGERPRINT_NOTEVAL) ||
(vfe->type & VERIEXEC_UNTRUSTED)) {
/* Calculate fingerprint for on-disk file. */
digest = (u_char *) malloc(vfe->ops->hash_len, M_VERIEXEC,
M_WAITOK);
error = veriexec_fp_calc(l, vp, vfe, digest);
if (error) {
veriexec_report("Fingerprint calculation error.",
name, NULL, REPORT_ALWAYS);
free(digest, M_VERIEXEC);
return (error);
}
/* Compare fingerprint with loaded data. */
if (veriexec_fp_cmp(vfe->ops, vfe->fp, digest) == 0) {
vfe->status = FINGERPRINT_VALID;
} else {
vfe->status = FINGERPRINT_NOMATCH;
}
free(digest, M_VERIEXEC);
}
if (!(vfe->type & flag)) {
veriexec_report("Incorrect access type.", name, l,
REPORT_ALWAYS|REPORT_ALARM);
/* IPS mode: Enforce access type. */
if (veriexec_strict >= VERIEXEC_IPS)
return (EPERM);
}
out:
/* No entry in the veriexec tables. */
if (vfe == NULL) {
veriexec_report("No entry.", name,
l, REPORT_VERBOSE);
/*
* Lockdown mode: Deny access to non-monitored files.
* IPS mode: Deny execution of non-monitored files.
*/
if ((veriexec_strict >= VERIEXEC_LOCKDOWN) ||
((veriexec_strict >= VERIEXEC_IPS) &&
(flag != VERIEXEC_FILE)))
return (EPERM);
return (0);
}
switch (vfe->status) {
case FINGERPRINT_NOTEVAL:
/* Should not happen. */
veriexec_report("Not-evaluated status "
"post evaluation; inconsistency detected.", name,
NULL, REPORT_ALWAYS|REPORT_PANIC);
case FINGERPRINT_VALID:
/* Valid fingerprint. */
veriexec_report("Match.", name, NULL,
REPORT_VERBOSE);
break;
case FINGERPRINT_NOMATCH:
/* Fingerprint mismatch. */
veriexec_report("Mismatch.", name,
NULL, REPORT_ALWAYS|REPORT_ALARM);
/* IDS mode: Deny access on fingerprint mismatch. */
if (veriexec_strict >= VERIEXEC_IDS)
error = EPERM;
break;
default:
/* Should never happen. */
veriexec_report("Invalid status "
"post evaluation.", name, NULL, REPORT_ALWAYS|REPORT_PANIC);
}
return (error);
}
#ifdef notyet
/*
* Evaluate per-page fingerprints.
*/
int
veriexec_page_verify(struct veriexec_file_entry *vfe, struct vm_page *pg,
size_t idx, struct lwp *l)
{
void *ctx;
u_char *fp;
u_char *page_fp;
int error;
vaddr_t kva;
if (vfe->page_fp_status == PAGE_FP_NONE)
return (0);
if (vfe->page_fp_status == PAGE_FP_FAIL)
return (EPERM);
if (idx >= vfe->npages)
return (0);
ctx = malloc(vfe->ops->context_size, M_VERIEXEC, M_WAITOK);
fp = malloc(vfe->ops->hash_len, M_VERIEXEC, M_WAITOK);
kva = uvm_km_alloc(kernel_map, PAGE_SIZE, 0, UVM_KMF_VAONLY | UVM_KMF_WAITVA);
pmap_kenter_pa(kva, VM_PAGE_TO_PHYS(pg), VM_PROT_READ);
page_fp = (u_char *) vfe->page_fp + (vfe->ops->hash_len * idx);
(vfe->ops->init)(ctx);
(vfe->ops->update)(ctx, (void *) kva,
((vfe->npages - 1) == idx) ? vfe->last_page_size
: PAGE_SIZE);
(vfe->ops->final)(fp, ctx);
pmap_kremove(kva, PAGE_SIZE);
uvm_km_free(kernel_map, kva, PAGE_SIZE, UVM_KMF_VAONLY);
error = veriexec_fp_cmp(vfe->ops, page_fp, fp);
if (error) {
const char *msg;
if (veriexec_strict > VERIEXEC_LEARNING) {
msg = "Pages modified: Killing process.";
} else {
msg = "Pages modified.";
error = 0;
}
veriexec_report(msg, "[page_in]", l, REPORT_ALWAYS|REPORT_ALARM);
if (error) {
ksiginfo_t ksi;
KSI_INIT(&ksi);
ksi.ksi_signo = SIGKILL;
ksi.ksi_code = SI_NOINFO;
ksi.ksi_pid = l->l_proc->p_pid;
ksi.ksi_uid = 0;
kpsignal(l->l_proc, &ksi, NULL);
}
}
free(ctx, M_VERIEXEC);
free(fp, M_VERIEXEC);
return (error);
}
#endif /* notyet */
/*
* Veriexec remove policy code.
*/
int
veriexec_removechk(struct vnode *vp, const char *pathbuf, struct lwp *l)
{
struct veriexec_file_entry *vfe;
struct veriexec_table_entry *vte;
vfe = veriexec_get(vp);
if (vfe == NULL) {
/* Lockdown mode: Deny access to non-monitored files. */
if (veriexec_strict >= VERIEXEC_LOCKDOWN)
return (EPERM);
return (0);
}
veriexec_report("Remove request.", pathbuf, l, REPORT_ALWAYS|REPORT_ALARM);
/* IDS mode: Deny removal of monitored files. */
if (veriexec_strict >= VERIEXEC_IDS)
return (EPERM);
fileassoc_clear(vp, veriexec_hook);
vte = veriexec_table_lookup(vp->v_mount);
KASSERT(vte != NULL);
vte->vte_count--;
return (0);
}
/*
* Veriexe rename policy.
*/
int
veriexec_renamechk(struct vnode *fromvp, const char *fromname,
struct vnode *tovp, const char *toname, struct lwp *l)
{
struct veriexec_file_entry *vfe, *tvfe;
if (veriexec_strict >= VERIEXEC_LOCKDOWN) {
log(LOG_ALERT, "Veriexec: Preventing rename of `%s' to "
"`%s', uid=%u, pid=%u: Lockdown mode.\n", fromname, toname,
kauth_cred_geteuid(l->l_cred), l->l_proc->p_pid);
return (EPERM);
}
vfe = veriexec_get(fromvp);
tvfe = NULL;
if (tovp != NULL)
tvfe = veriexec_get(tovp);
if ((vfe != NULL) || (tvfe != NULL)) {
if (veriexec_strict >= VERIEXEC_IPS) {
log(LOG_ALERT, "Veriexec: Preventing rename of `%s' "
"to `%s', uid=%u, pid=%u: IPS mode, file "
"monitored.\n", fromname, toname,
kauth_cred_geteuid(l->l_cred),
l->l_proc->p_pid);
return (EPERM);
}
log(LOG_NOTICE, "Veriexec: Monitored file `%s' renamed to "
"`%s', uid=%u, pid=%u.\n", fromname, toname,
kauth_cred_geteuid(l->l_cred), l->l_proc->p_pid);
}
return (0);
}
/*
* Routine for maintaining mostly consistent message formats in Verified
* Exec.
*/
void
veriexec_report(const u_char *msg, const u_char *filename, struct lwp *l, int f)
{
if (msg == NULL || filename == NULL)
return;
if (((f & REPORT_LOGMASK) >> 1) <= veriexec_verbose) {
if (!(f & REPORT_ALARM) || (l == NULL))
log(LOG_NOTICE, "Veriexec: %s [%s]\n", msg,
filename);
else
log(LOG_ALERT, "Veriexec: %s [%s, pid=%u, uid=%u, "
"gid=%u]\n", msg, filename, l->l_proc->p_pid,
kauth_cred_getuid(l->l_cred),
kauth_cred_getgid(l->l_cred));
}
if (f & REPORT_PANIC)
panic("Veriexec: Unrecoverable error.");
}
static void
veriexec_clear(void *data)
{
struct veriexec_file_entry *vfe = data;
if (vfe != NULL) {
if (vfe->fp != NULL)
free(vfe->fp, M_VERIEXEC);
if (vfe->page_fp != NULL)
free(vfe->page_fp, M_VERIEXEC);
free(vfe, M_VERIEXEC);
}
}
/*
* Invalidate a Veriexec file entry.
* XXX: This should be updated when per-page fingerprints are added.
*/
void
veriexec_purge(struct vnode *vp)
{
struct veriexec_file_entry *vfe;
vfe = veriexec_get(vp);
if (vfe == NULL)
return;
vfe->status = FINGERPRINT_NOTEVAL;
}
/*
* Enforce raw disk access policy.
*
* IDS mode: Invalidate fingerprints on a mount if it's opened for writing.
* IPS mode: Don't allow raw writing to disks we monitor.
* Lockdown mode: Don't allow raw writing to all disks.
*
* XXX: This is bogus. There's an obvious race condition between the time
* XXX: the disk is open for writing, in which an attacker can access a
* XXX: monitored file to get its signature cached again, and when the raw
* XXX: file is overwritten on disk.
* XXX:
* XXX: To solve this, we need something like the following:
* XXX: open raw disk:
* XXX: - raise refcount,
* XXX: - invalidate fingerprints,
* XXX: - mark all entries for that disk with "no cache" flag
* XXX:
* XXX: veriexec_verify:
* XXX: - if "no cache", don't cache evaluation result
* XXX:
* XXX: close raw disk:
* XXX: - lower refcount,
* XXX: - if refcount == 0, remove "no cache" flag from all entries
*/
static int
veriexec_raw_cb(kauth_cred_t cred, kauth_action_t action, void *cookie,
void *arg0, void *arg1, void *arg2, void *arg3)
{
int result;
enum kauth_device_req req;
struct veriexec_table_entry *vte;
result = KAUTH_RESULT_DENY;
req = (enum kauth_device_req)arg0;
switch (action) {
case KAUTH_DEVICE_RAWIO_SPEC: {
struct vnode *vp, *bvp;
dev_t dev;
int d_type;
if (req == KAUTH_REQ_DEVICE_RAWIO_SPEC_READ) {
result = KAUTH_RESULT_DEFER;
break;
}
vp = arg1;
KASSERT(vp != NULL);
dev = vp->v_un.vu_specinfo->si_rdev;
d_type = D_OTHER;
bvp = NULL;
/* Handle /dev/mem and /dev/kmem. */
if ((vp->v_type == VCHR) && iskmemdev(dev)) {
if (veriexec_strict < VERIEXEC_IPS)
result = KAUTH_RESULT_DEFER;
break;
}
switch (vp->v_type) {
case VCHR: {
const struct cdevsw *cdev;
cdev = cdevsw_lookup(dev);
if (cdev != NULL) {
dev_t blkdev;
blkdev = devsw_chr2blk(dev);
if (blkdev != NODEV) {
vfinddev(blkdev, VBLK, &bvp);
if (bvp != NULL)
d_type = cdev->d_type;
}
}
break;
}
case VBLK: {
const struct bdevsw *bdev;
bdev = bdevsw_lookup(dev);
if (bdev != NULL)
d_type = bdev->d_type;
bvp = vp;
break;
}
default:
result = KAUTH_RESULT_DEFER;
break;
}
if (d_type != D_DISK) {
result = KAUTH_RESULT_DEFER;
break;
}
/*
* XXX: See vfs_mountedon() comment in secmodel/bsd44.
*/
vte = veriexec_table_lookup(bvp->v_mount);
if (vte == NULL) {
result = KAUTH_RESULT_DEFER;
break;
}
switch (veriexec_strict) {
case VERIEXEC_LEARNING:
case VERIEXEC_IDS:
result = KAUTH_RESULT_DEFER;
fileassoc_table_run(bvp->v_mount, veriexec_hook,
(fileassoc_cb_t)veriexec_purge);
break;
case VERIEXEC_IPS:
result = KAUTH_RESULT_DENY;
break;
case VERIEXEC_LOCKDOWN:
result = KAUTH_RESULT_DENY;
break;
}
break;
}
case KAUTH_DEVICE_RAWIO_PASSTHRU:
/* XXX What can we do here? */
if (veriexec_strict < VERIEXEC_IPS)
result = KAUTH_RESULT_DEFER;
break;
default:
result = KAUTH_RESULT_DEFER;
break;
}
return (result);
}
/*
* Add a file to be monitored by Veriexec.
*
* Expected elements in dict: file, fp, fp-type, entry-type.
*/
int
veriexec_file_add(struct lwp *l, prop_dictionary_t dict)
{
struct veriexec_table_entry *vte;
struct veriexec_file_entry *vfe, *hh;
struct nameidata nid;
const char *file, *fp_type;
int error;
file = prop_string_cstring_nocopy(prop_dictionary_get(dict, "file"));
NDINIT(&nid, LOOKUP, FOLLOW, UIO_SYSSPACE, file, l);
error = namei(&nid);
if (error)
return (error);
/* Add only regular files. */
if (nid.ni_vp->v_type != VREG) {
log(LOG_ERR, "Veriexec: Not adding `%s': Not a regular file.\n",
file);
error = EINVAL;
goto out;
}
vfe = malloc(sizeof(*vfe), M_VERIEXEC, M_WAITOK);
/* Lookup fingerprint hashing algorithm. */
fp_type = prop_string_cstring_nocopy(prop_dictionary_get(dict,
"fp-type"));
if ((vfe->ops = veriexec_fpops_lookup(fp_type)) == NULL) {
free(vfe, M_VERIEXEC);
log(LOG_ERR, "Veriexec: Invalid or unknown fingerprint type "
"`%s' for file `%s'.\n", fp_type, file);
error = EINVAL;
goto out;
}
if (prop_data_size(prop_dictionary_get(dict, "fp")) !=
vfe->ops->hash_len) {
free(vfe, M_VERIEXEC);
log(LOG_ERR, "Veriexec: Bad fingerprint length for `%s'.\n",
file);
error = EINVAL;
goto out;
}
vfe->fp = malloc(vfe->ops->hash_len, M_VERIEXEC, M_WAITOK);
memcpy(vfe->fp, prop_data_data_nocopy(prop_dictionary_get(dict, "fp")),
vfe->ops->hash_len);
/*
* See if we already have an entry for this file. If we do, then
* let the user know and silently pretend to succeed.
*/
hh = veriexec_get(nid.ni_vp);
if (hh != NULL) {
boolean_t fp_mismatch;
if (strcmp(vfe->ops->type, fp_type) ||
memcmp(hh->fp, vfe->fp, hh->ops->hash_len))
fp_mismatch = TRUE;
else
fp_mismatch = FALSE;
if ((veriexec_verbose >= 1) || fp_mismatch)
log(LOG_NOTICE, "Veriexec: Duplicate entry for `%s' "
"ignored. (%s fingerprint)\n", file,
fp_mismatch ? "different" : "same");
free(vfe->fp, M_VERIEXEC);
free(vfe, M_VERIEXEC);
error = 0;
goto out;
}
/* Continue entry initialization. */
prop_dictionary_get_uint8(dict, "entry-type", &vfe->type);
vfe->status = FINGERPRINT_NOTEVAL;
vfe->page_fp = NULL;
vfe->page_fp_status = PAGE_FP_NONE;
vfe->npages = 0;
vfe->last_page_size = 0;
error = fileassoc_add(nid.ni_vp, veriexec_hook, vfe);
if (error) {
free(vfe->fp, M_VERIEXEC);
free(vfe, M_VERIEXEC);
goto out;
}
vte = veriexec_table_lookup(nid.ni_vp->v_mount);
vte->vte_count++;
veriexec_report("New entry.", file, NULL, REPORT_DEBUG);
out:
vrele(nid.ni_vp);
return (error);
}
/*
* Create a new Veriexec table using hints from userland.
*
* Expects dict to have mount and count.
*/
int
veriexec_table_add(struct lwp *l, prop_dictionary_t dict)
{
struct veriexec_table_entry *vte;
struct nameidata nid;
u_char buf[16];
int error;
static ONCE_DECL(control);
error = RUN_ONCE(&control, veriexec_mountspecific_init);
if (error) {
return error;
}
NDINIT(&nid, LOOKUP, FOLLOW, UIO_SYSSPACE,
prop_string_cstring_nocopy(prop_dictionary_get(dict, "mount")), l);
error = namei(&nid);
if (error)
return (error);
vte = malloc(sizeof(*vte), M_VERIEXEC, M_WAITOK | M_ZERO);
mount_setspecific(nid.ni_vp->v_mount, veriexec_mountspecific_key, vte);
snprintf(buf, sizeof(buf), "table%u", veriexec_tablecount++);
sysctl_createv(NULL, 0, &veriexec_count_node, &vte->vte_node,
0, CTLTYPE_NODE, buf, NULL, NULL, 0, NULL,
0, CTL_CREATE, CTL_EOL);
sysctl_createv(NULL, 0, &vte->vte_node, NULL,
CTLFLAG_READONLY, CTLTYPE_STRING, "mntpt",
NULL, NULL, 0, nid.ni_vp->v_mount->mnt_stat.f_mntonname,
0, CTL_CREATE, CTL_EOL);
sysctl_createv(NULL, 0, &vte->vte_node, NULL,
CTLFLAG_READONLY, CTLTYPE_STRING, "fstype",
NULL, NULL, 0, nid.ni_vp->v_mount->mnt_stat.f_fstypename,
0, CTL_CREATE, CTL_EOL);
sysctl_createv(NULL, 0, &vte->vte_node, NULL,
CTLFLAG_READONLY, CTLTYPE_QUAD, "nentries",
NULL, NULL, 0, &vte->vte_count, 0, CTL_CREATE, CTL_EOL);
vrele(nid.ni_vp);
return (error);
}
int
veriexec_table_delete(struct lwp *l, struct mount *mp) {
struct veriexec_table_entry *vte;
vte = veriexec_table_lookup(mp);
if (vte == NULL)
return (ENOENT);
return (fileassoc_table_clear(mp, veriexec_hook));
}
int
veriexec_file_delete(struct lwp *l, struct vnode *vp) {
struct veriexec_table_entry *vte;
int error;
vte = veriexec_table_lookup(vp->v_mount);
if (vte == NULL)
return (ENOENT);
error = fileassoc_clear(vp, veriexec_hook);
if (!error)
vte->vte_count--;
return (error);
}
/*
* Convert Veriexec entry data to a dictionary readable by userland tools.
*/
int
veriexec_convert(struct vnode *vp, prop_dictionary_t rdict)
{
struct veriexec_file_entry *vfe;
vfe = veriexec_get(vp);
if (vfe == NULL)
return (ENOENT);
prop_dictionary_set_uint8(rdict, "entry-type", vfe->type);
prop_dictionary_set_uint8(rdict, "status", vfe->status);
prop_dictionary_set(rdict, "fp-type",
prop_string_create_cstring(vfe->ops->type));
prop_dictionary_set(rdict, "fp",
prop_data_create_data(vfe->fp, vfe->ops->hash_len));
return (0);
}
int
veriexec_unmountchk(struct mount *mp)
{
int error;
if (doing_shutdown)
return (0);
switch (veriexec_strict) {
case VERIEXEC_LEARNING:
case VERIEXEC_IDS:
if (veriexec_table_lookup(mp) != NULL) {
log(LOG_INFO, "Veriexec: IDS mode, allowing unmount "
"of \"%s\".\n", mp->mnt_stat.f_mntonname);
}
error = 0;
break;
case VERIEXEC_IPS: {
struct veriexec_table_entry *vte;
vte = veriexec_table_lookup(mp);
if ((vte != NULL) && (vte->vte_count > 0)) {
log(LOG_ALERT, "Veriexec: IPS mode, preventing"
" unmount of \"%s\" with monitored files.\n",
mp->mnt_stat.f_mntonname);
error = EPERM;
} else
error = 0;
break;
}
case VERIEXEC_LOCKDOWN:
default:
log(LOG_ALERT, "Veriexec: Lockdown mode, preventing unmount "
"of \"%s\".\n", mp->mnt_stat.f_mntonname);
error = EPERM;
break;
}
return (error);
}
int
veriexec_openchk(struct lwp *l, struct vnode *vp, const char *path, int fmode)
{
boolean_t monitored = FALSE;
int error = 0;
if (vp == NULL) {
/* If no creation requested, let this fail normally. */
if (!(fmode & O_CREAT)) {
error = 0;
goto out;
}
/* Lockdown mode: Prevent creation of new files. */
if (veriexec_strict >= VERIEXEC_LOCKDOWN) {
log(LOG_ALERT, "Veriexec: Preventing new file "
"creation in `%s'.\n", path);
error = EPERM;
}
goto out;
}
error = veriexec_verify(l, vp, path, VERIEXEC_FILE,
&monitored);
if (error)
goto out;
if (monitored && ((fmode & FWRITE) || (fmode & O_TRUNC))) {
veriexec_report("Write access request.", path, l,
REPORT_ALWAYS | REPORT_ALARM);
/* IPS mode: Deny writing to/truncating monitored files. */
if (veriexec_strict >= VERIEXEC_IPS)
error = EPERM;
else
veriexec_purge(vp);
}
out:
return (error);
}
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