opnsense-src/lib/libcasper/services/cap_fileargs/cap_fileargs.c
Mariusz Zaborski 9509775394 cap_filergs: limit size of the file name
The limit of the name in fileargs is twice the size of the MAXPATH.
The nvlist will not add an element with the longer name.
We can detect at this point that the path is too big, and simple return
the same error as open(2) would.

PR:		239700
Reported by:	markj
Tested by:	markj
MFC after:	2 weeks
2019-08-07 19:30:33 +00:00

679 lines
13 KiB
C

/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2018 Mariusz Zaborski <oshogbo@FreeBSD.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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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>
__FBSDID("$FreeBSD$");
#include <sys/types.h>
#include <sys/capsicum.h>
#include <sys/sysctl.h>
#include <sys/cnv.h>
#include <sys/dnv.h>
#include <sys/nv.h>
#include <sys/stat.h>
#include <assert.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <libcasper.h>
#include <libcasper_service.h>
#include "cap_fileargs.h"
#define CACHE_SIZE 128
#define FILEARGS_MAGIC 0xFA00FA00
struct fileargs {
uint32_t fa_magic;
nvlist_t *fa_cache;
cap_channel_t *fa_chann;
int fa_fdflags;
};
static int
fileargs_get_lstat_cache(fileargs_t *fa, const char *name, struct stat *sb)
{
const nvlist_t *nvl;
size_t size;
const void *buf;
assert(fa != NULL);
assert(fa->fa_magic == FILEARGS_MAGIC);
assert(name != NULL);
if (fa->fa_cache == NULL)
return (-1);
nvl = dnvlist_get_nvlist(fa->fa_cache, name, NULL);
if (nvl == NULL)
return (-1);
if (!nvlist_exists_binary(nvl, "stat")) {
return (-1);
}
buf = nvlist_get_binary(nvl, "stat", &size);
assert(size == sizeof(*sb));
memcpy(sb, buf, size);
return (0);
}
static int
fileargs_get_fd_cache(fileargs_t *fa, const char *name)
{
int fd;
const nvlist_t *nvl;
nvlist_t *tnvl;
assert(fa != NULL);
assert(fa->fa_magic == FILEARGS_MAGIC);
assert(name != NULL);
if (fa->fa_cache == NULL)
return (-1);
if ((fa->fa_fdflags & O_CREAT) != 0)
return (-1);
nvl = dnvlist_get_nvlist(fa->fa_cache, name, NULL);
if (nvl == NULL)
return (-1);
tnvl = nvlist_take_nvlist(fa->fa_cache, name);
if (!nvlist_exists_descriptor(tnvl, "fd")) {
nvlist_destroy(tnvl);
return (-1);
}
fd = nvlist_take_descriptor(tnvl, "fd");
nvlist_destroy(tnvl);
if ((fa->fa_fdflags & O_CLOEXEC) != O_CLOEXEC) {
if (fcntl(fd, F_SETFD, fa->fa_fdflags) == -1) {
close(fd);
return (-1);
}
}
return (fd);
}
static void
fileargs_set_cache(fileargs_t *fa, nvlist_t *nvl)
{
nvlist_destroy(fa->fa_cache);
fa->fa_cache = nvl;
}
static nvlist_t*
fileargs_fetch(fileargs_t *fa, const char *name, const char *cmd)
{
nvlist_t *nvl;
int serrno;
assert(fa != NULL);
assert(name != NULL);
nvl = nvlist_create(NV_FLAG_NO_UNIQUE);
nvlist_add_string(nvl, "cmd", cmd);
nvlist_add_string(nvl, "name", name);
nvl = cap_xfer_nvlist(fa->fa_chann, nvl);
if (nvl == NULL)
return (NULL);
if (nvlist_get_number(nvl, "error") != 0) {
serrno = (int)nvlist_get_number(nvl, "error");
nvlist_destroy(nvl);
errno = serrno;
return (NULL);
}
return (nvl);
}
static nvlist_t *
fileargs_create_limit(int argc, const char * const *argv, int flags,
mode_t mode, cap_rights_t *rightsp, int operations)
{
nvlist_t *limits;
int i;
limits = nvlist_create(NV_FLAG_NO_UNIQUE);
if (limits == NULL)
return (NULL);
nvlist_add_number(limits, "flags", flags);
nvlist_add_number(limits, "operations", operations);
if (rightsp != NULL) {
nvlist_add_binary(limits, "cap_rights", rightsp,
sizeof(*rightsp));
}
if ((flags & O_CREAT) != 0)
nvlist_add_number(limits, "mode", (uint64_t)mode);
for (i = 0; i < argc; i++) {
if (strlen(argv[i]) >= MAXPATHLEN) {
nvlist_destroy(limits);
errno = ENAMETOOLONG;
return (NULL);
}
nvlist_add_null(limits, argv[i]);
}
return (limits);
}
static fileargs_t *
fileargs_create(cap_channel_t *chan, int fdflags)
{
fileargs_t *fa;
fa = malloc(sizeof(*fa));
if (fa != NULL) {
fa->fa_cache = NULL;
fa->fa_chann = chan;
fa->fa_fdflags = fdflags;
fa->fa_magic = FILEARGS_MAGIC;
}
return (fa);
}
fileargs_t *
fileargs_init(int argc, char *argv[], int flags, mode_t mode,
cap_rights_t *rightsp, int operations)
{
nvlist_t *limits;
if (argc <= 0 || argv == NULL) {
return (fileargs_create(NULL, 0));
}
limits = fileargs_create_limit(argc, (const char * const *)argv, flags,
mode, rightsp, operations);
if (limits == NULL)
return (NULL);
return (fileargs_initnv(limits));
}
fileargs_t *
fileargs_cinit(cap_channel_t *cas, int argc, char *argv[], int flags,
mode_t mode, cap_rights_t *rightsp, int operations)
{
nvlist_t *limits;
if (argc <= 0 || argv == NULL) {
return (fileargs_create(NULL, 0));
}
limits = fileargs_create_limit(argc, (const char * const *)argv, flags,
mode, rightsp, operations);
if (limits == NULL)
return (NULL);
return (fileargs_cinitnv(cas, limits));
}
fileargs_t *
fileargs_initnv(nvlist_t *limits)
{
cap_channel_t *cas;
fileargs_t *fa;
if (limits == NULL) {
return (fileargs_create(NULL, 0));
}
cas = cap_init();
if (cas == NULL) {
nvlist_destroy(limits);
return (NULL);
}
fa = fileargs_cinitnv(cas, limits);
cap_close(cas);
return (fa);
}
fileargs_t *
fileargs_cinitnv(cap_channel_t *cas, nvlist_t *limits)
{
cap_channel_t *chann;
fileargs_t *fa;
int serrno, ret;
int flags, operations;
assert(cas != NULL);
if (limits == NULL) {
return (fileargs_create(NULL, 0));
}
chann = NULL;
fa = NULL;
chann = cap_service_open(cas, "system.fileargs");
if (chann == NULL) {
nvlist_destroy(limits);
return (NULL);
}
flags = nvlist_get_number(limits, "flags");
operations = nvlist_get_number(limits, "operations");
/* Limits are consumed no need to free them. */
ret = cap_limit_set(chann, limits);
if (ret < 0)
goto out;
fa = fileargs_create(chann, flags);
if (fa == NULL)
goto out;
return (fa);
out:
serrno = errno;
if (chann != NULL)
cap_close(chann);
errno = serrno;
return (NULL);
}
int
fileargs_open(fileargs_t *fa, const char *name)
{
int fd;
nvlist_t *nvl;
char *cmd;
assert(fa != NULL);
assert(fa->fa_magic == FILEARGS_MAGIC);
if (name == NULL) {
errno = EINVAL;
return (-1);
}
if (fa->fa_chann == NULL) {
errno = ENOTCAPABLE;
return (-1);
}
fd = fileargs_get_fd_cache(fa, name);
if (fd != -1)
return (fd);
nvl = fileargs_fetch(fa, name, "open");
if (nvl == NULL)
return (-1);
fd = nvlist_take_descriptor(nvl, "fd");
cmd = nvlist_take_string(nvl, "cmd");
if (strcmp(cmd, "cache") == 0)
fileargs_set_cache(fa, nvl);
else
nvlist_destroy(nvl);
free(cmd);
return (fd);
}
FILE *
fileargs_fopen(fileargs_t *fa, const char *name, const char *mode)
{
int fd;
if ((fd = fileargs_open(fa, name)) < 0) {
return (NULL);
}
return (fdopen(fd, mode));
}
int
fileargs_lstat(fileargs_t *fa, const char *name, struct stat *sb)
{
nvlist_t *nvl;
const void *buf;
size_t size;
char *cmd;
assert(fa != NULL);
assert(fa->fa_magic == FILEARGS_MAGIC);
if (name == NULL) {
errno = EINVAL;
return (-1);
}
if (sb == NULL) {
errno = EFAULT;
return (-1);
}
if (fa->fa_chann == NULL) {
errno = ENOTCAPABLE;
return (-1);
}
if (fileargs_get_lstat_cache(fa, name, sb) != -1)
return (0);
nvl = fileargs_fetch(fa, name, "lstat");
if (nvl == NULL)
return (-1);
buf = nvlist_get_binary(nvl, "stat", &size);
assert(size == sizeof(*sb));
memcpy(sb, buf, size);
cmd = nvlist_take_string(nvl, "cmd");
if (strcmp(cmd, "cache") == 0)
fileargs_set_cache(fa, nvl);
else
nvlist_destroy(nvl);
free(cmd);
return (0);
}
void
fileargs_free(fileargs_t *fa)
{
if (fa == NULL)
return;
assert(fa->fa_magic == FILEARGS_MAGIC);
nvlist_destroy(fa->fa_cache);
if (fa->fa_chann != NULL) {
cap_close(fa->fa_chann);
}
explicit_bzero(&fa->fa_magic, sizeof(fa->fa_magic));
free(fa);
}
cap_channel_t *
fileargs_unwrap(fileargs_t *fa, int *flags)
{
cap_channel_t *chan;
if (fa == NULL)
return (NULL);
assert(fa->fa_magic == FILEARGS_MAGIC);
chan = fa->fa_chann;
if (flags != NULL) {
*flags = fa->fa_fdflags;
}
nvlist_destroy(fa->fa_cache);
explicit_bzero(&fa->fa_magic, sizeof(fa->fa_magic));
free(fa);
return (chan);
}
fileargs_t *
fileargs_wrap(cap_channel_t *chan, int fdflags)
{
if (chan == NULL) {
return (NULL);
}
return (fileargs_create(chan, fdflags));
}
/*
* Service functions.
*/
static const char *lastname;
static void *cacheposition;
static bool allcached;
static const cap_rights_t *caprightsp;
static int capflags;
static int allowed_operations;
static mode_t capmode;
static int
open_file(const char *name)
{
int fd, serrno;
if ((capflags & O_CREAT) == 0)
fd = open(name, capflags);
else
fd = open(name, capflags, capmode);
if (fd < 0)
return (-1);
if (caprightsp != NULL) {
if (cap_rights_limit(fd, caprightsp) < 0 && errno != ENOSYS) {
serrno = errno;
close(fd);
errno = serrno;
return (-1);
}
}
return (fd);
}
static void
fileargs_add_cache(nvlist_t *nvlout, const nvlist_t *limits,
const char *curent_name)
{
int type, i, fd;
void *cookie;
nvlist_t *new;
const char *fname;
struct stat sb;
if ((capflags & O_CREAT) != 0) {
allcached = true;
return;
}
cookie = cacheposition;
for (i = 0; i < CACHE_SIZE + 1; i++) {
fname = nvlist_next(limits, &type, &cookie);
if (fname == NULL) {
cacheposition = NULL;
lastname = NULL;
allcached = true;
return;
}
/* We doing that to catch next element name. */
if (i == CACHE_SIZE) {
break;
}
if (type != NV_TYPE_NULL ||
(curent_name != NULL && strcmp(fname, curent_name) == 0)) {
curent_name = NULL;
i--;
continue;
}
new = nvlist_create(NV_FLAG_NO_UNIQUE);
if ((allowed_operations & FA_OPEN) != 0) {
fd = open_file(fname);
if (fd < 0) {
i--;
nvlist_destroy(new);
continue;
}
nvlist_move_descriptor(new, "fd", fd);
}
if ((allowed_operations & FA_LSTAT) != 0) {
if (lstat(fname, &sb) < 0) {
i--;
nvlist_destroy(new);
continue;
}
nvlist_add_binary(new, "stat", &sb, sizeof(sb));
}
nvlist_add_nvlist(nvlout, fname, new);
}
cacheposition = cookie;
lastname = fname;
}
static bool
fileargs_allowed(const nvlist_t *limits, const nvlist_t *request, int operation)
{
const char *name;
if ((allowed_operations & operation) == 0)
return (false);
name = dnvlist_get_string(request, "name", NULL);
if (name == NULL)
return (false);
/* Fast path. */
if (lastname != NULL && strcmp(name, lastname) == 0)
return (true);
if (!nvlist_exists_null(limits, name))
return (false);
return (true);
}
static int
fileargs_limit(const nvlist_t *oldlimits, const nvlist_t *newlimits)
{
if (oldlimits != NULL)
return (ENOTCAPABLE);
capflags = (int)dnvlist_get_number(newlimits, "flags", 0);
allowed_operations = (int)dnvlist_get_number(newlimits, "operations", 0);
if ((capflags & O_CREAT) != 0)
capmode = (mode_t)nvlist_get_number(newlimits, "mode");
else
capmode = 0;
caprightsp = dnvlist_get_binary(newlimits, "cap_rights", NULL, NULL, 0);
return (0);
}
static int
fileargs_command_lstat(const nvlist_t *limits, nvlist_t *nvlin,
nvlist_t *nvlout)
{
int error;
const char *name;
struct stat sb;
if (limits == NULL)
return (ENOTCAPABLE);
if (!fileargs_allowed(limits, nvlin, FA_LSTAT))
return (ENOTCAPABLE);
name = nvlist_get_string(nvlin, "name");
error = lstat(name, &sb);
if (error < 0)
return (errno);
if (!allcached && (lastname == NULL ||
strcmp(name, lastname) == 0)) {
nvlist_add_string(nvlout, "cmd", "cache");
fileargs_add_cache(nvlout, limits, name);
} else {
nvlist_add_string(nvlout, "cmd", "lstat");
}
nvlist_add_binary(nvlout, "stat", &sb, sizeof(sb));
return (0);
}
static int
fileargs_command_open(const nvlist_t *limits, nvlist_t *nvlin,
nvlist_t *nvlout)
{
int fd;
const char *name;
if (limits == NULL)
return (ENOTCAPABLE);
if (!fileargs_allowed(limits, nvlin, FA_OPEN))
return (ENOTCAPABLE);
name = nvlist_get_string(nvlin, "name");
fd = open_file(name);
if (fd < 0)
return (errno);
if (!allcached && (lastname == NULL ||
strcmp(name, lastname) == 0)) {
nvlist_add_string(nvlout, "cmd", "cache");
fileargs_add_cache(nvlout, limits, name);
} else {
nvlist_add_string(nvlout, "cmd", "open");
}
nvlist_move_descriptor(nvlout, "fd", fd);
return (0);
}
static int
fileargs_command(const char *cmd, const nvlist_t *limits,
nvlist_t *nvlin, nvlist_t *nvlout)
{
if (strcmp(cmd, "open") == 0)
return (fileargs_command_open(limits, nvlin, nvlout));
if (strcmp(cmd, "lstat") == 0)
return (fileargs_command_lstat(limits, nvlin, nvlout));
return (EINVAL);
}
CREATE_SERVICE("system.fileargs", fileargs_limit, fileargs_command,
CASPER_SERVICE_FD | CASPER_SERVICE_STDIO | CASPER_SERVICE_NO_UNIQ_LIMITS);