freebsd-skq/sbin/hastd/subr.c

300 lines
7.8 KiB
C
Raw Normal View History

/*-
* Copyright (c) 2010 The FreeBSD Foundation
2011-03-22 21:19:51 +00:00
* Copyright (c) 2011 Pawel Jakub Dawidek <pawel@dawidek.net>
* All rights reserved.
*
* This software was developed by Pawel Jakub Dawidek under sponsorship from
* the FreeBSD Foundation.
*
* 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/param.h>
#include <sys/disk.h>
#include <sys/ioctl.h>
#include <sys/jail.h>
#include <sys/stat.h>
#ifdef HAVE_CAPSICUM
#include <sys/capsicum.h>
#include <geom/gate/g_gate.h>
#endif
#include <errno.h>
#include <fcntl.h>
#include <pwd.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <pjdlog.h>
#include "hast.h"
#include "subr.h"
int
vsnprlcat(char *str, size_t size, const char *fmt, va_list ap)
{
size_t len;
len = strlen(str);
return (vsnprintf(str + len, size - len, fmt, ap));
}
int
snprlcat(char *str, size_t size, const char *fmt, ...)
{
va_list ap;
int result;
va_start(ap, fmt);
result = vsnprlcat(str, size, fmt, ap);
va_end(ap);
return (result);
}
int
provinfo(struct hast_resource *res, bool dowrite)
{
struct stat sb;
PJDLOG_ASSERT(res->hr_localpath != NULL &&
res->hr_localpath[0] != '\0');
if (res->hr_localfd == -1) {
res->hr_localfd = open(res->hr_localpath,
dowrite ? O_RDWR : O_RDONLY);
if (res->hr_localfd == -1) {
pjdlog_errno(LOG_ERR, "Unable to open %s",
res->hr_localpath);
return (-1);
}
}
if (fstat(res->hr_localfd, &sb) == -1) {
pjdlog_errno(LOG_ERR, "Unable to stat %s", res->hr_localpath);
return (-1);
}
if (S_ISCHR(sb.st_mode)) {
/*
* If this is character device, it is most likely GEOM provider.
*/
if (ioctl(res->hr_localfd, DIOCGMEDIASIZE,
&res->hr_local_mediasize) == -1) {
pjdlog_errno(LOG_ERR,
"Unable obtain provider %s mediasize",
res->hr_localpath);
return (-1);
}
if (ioctl(res->hr_localfd, DIOCGSECTORSIZE,
&res->hr_local_sectorsize) == -1) {
pjdlog_errno(LOG_ERR,
"Unable obtain provider %s sectorsize",
res->hr_localpath);
return (-1);
}
} else if (S_ISREG(sb.st_mode)) {
/*
* We also support regular files for which we hardcode
* sector size of 512 bytes.
*/
res->hr_local_mediasize = sb.st_size;
res->hr_local_sectorsize = 512;
} else {
/*
* We support no other file types.
*/
pjdlog_error("%s is neither GEOM provider nor regular file.",
res->hr_localpath);
errno = EFTYPE;
return (-1);
}
return (0);
}
const char *
role2str(int role)
{
switch (role) {
case HAST_ROLE_INIT:
return ("init");
case HAST_ROLE_PRIMARY:
return ("primary");
case HAST_ROLE_SECONDARY:
return ("secondary");
}
return ("unknown");
}
int
2012-01-06 12:27:17 +00:00
drop_privs(const struct hast_resource *res)
{
char jailhost[sizeof(res->hr_name) * 2];
struct jail jailst;
struct passwd *pw;
uid_t ruid, euid, suid;
gid_t rgid, egid, sgid;
gid_t gidset[1];
bool capsicum, jailed;
/*
* According to getpwnam(3) we have to clear errno before calling the
* function to be able to distinguish between an error and missing
* entry (with is not treated as error by getpwnam(3)).
*/
errno = 0;
pw = getpwnam(HAST_USER);
if (pw == NULL) {
if (errno != 0) {
pjdlog_errno(LOG_ERR,
"Unable to find info about '%s' user", HAST_USER);
return (-1);
} else {
pjdlog_error("'%s' user doesn't exist.", HAST_USER);
errno = ENOENT;
return (-1);
}
}
bzero(&jailst, sizeof(jailst));
jailst.version = JAIL_API_VERSION;
jailst.path = pw->pw_dir;
if (res == NULL) {
(void)snprintf(jailhost, sizeof(jailhost), "hastctl");
} else {
(void)snprintf(jailhost, sizeof(jailhost), "hastd: %s (%s)",
res->hr_name, role2str(res->hr_role));
}
jailst.hostname = jailhost;
jailst.jailname = NULL;
jailst.ip4s = 0;
jailst.ip4 = NULL;
jailst.ip6s = 0;
jailst.ip6 = NULL;
if (jail(&jailst) >= 0) {
jailed = true;
} else {
jailed = false;
pjdlog_errno(LOG_WARNING,
"Unable to jail to directory to %s", pw->pw_dir);
if (chroot(pw->pw_dir) == -1) {
pjdlog_errno(LOG_ERR,
"Unable to change root directory to %s",
pw->pw_dir);
return (-1);
}
}
PJDLOG_VERIFY(chdir("/") == 0);
gidset[0] = pw->pw_gid;
if (setgroups(1, gidset) == -1) {
pjdlog_errno(LOG_ERR, "Unable to set groups to gid %u",
(unsigned int)pw->pw_gid);
return (-1);
}
if (setgid(pw->pw_gid) == -1) {
pjdlog_errno(LOG_ERR, "Unable to set gid to %u",
(unsigned int)pw->pw_gid);
return (-1);
}
if (setuid(pw->pw_uid) == -1) {
pjdlog_errno(LOG_ERR, "Unable to set uid to %u",
(unsigned int)pw->pw_uid);
return (-1);
}
#ifdef HAVE_CAPSICUM
capsicum = (cap_enter() == 0);
if (!capsicum) {
pjdlog_common(LOG_DEBUG, 1, errno,
"Unable to sandbox using capsicum");
} else if (res != NULL) {
Change the cap_rights_t type from uint64_t to a structure that we can extend in the future in a backward compatible (API and ABI) way. The cap_rights_t represents capability rights. We used to use one bit to represent one right, but we are running out of spare bits. Currently the new structure provides place for 114 rights (so 50 more than the previous cap_rights_t), but it is possible to grow the structure to hold at least 285 rights, although we can make it even larger if 285 rights won't be enough. The structure definition looks like this: struct cap_rights { uint64_t cr_rights[CAP_RIGHTS_VERSION + 2]; }; The initial CAP_RIGHTS_VERSION is 0. The top two bits in the first element of the cr_rights[] array contain total number of elements in the array - 2. This means if those two bits are equal to 0, we have 2 array elements. The top two bits in all remaining array elements should be 0. The next five bits in all array elements contain array index. Only one bit is used and bit position in this five-bits range defines array index. This means there can be at most five array elements in the future. To define new right the CAPRIGHT() macro must be used. The macro takes two arguments - an array index and a bit to set, eg. #define CAP_PDKILL CAPRIGHT(1, 0x0000000000000800ULL) We still support aliases that combine few rights, but the rights have to belong to the same array element, eg: #define CAP_LOOKUP CAPRIGHT(0, 0x0000000000000400ULL) #define CAP_FCHMOD CAPRIGHT(0, 0x0000000000002000ULL) #define CAP_FCHMODAT (CAP_FCHMOD | CAP_LOOKUP) There is new API to manage the new cap_rights_t structure: cap_rights_t *cap_rights_init(cap_rights_t *rights, ...); void cap_rights_set(cap_rights_t *rights, ...); void cap_rights_clear(cap_rights_t *rights, ...); bool cap_rights_is_set(const cap_rights_t *rights, ...); bool cap_rights_is_valid(const cap_rights_t *rights); void cap_rights_merge(cap_rights_t *dst, const cap_rights_t *src); void cap_rights_remove(cap_rights_t *dst, const cap_rights_t *src); bool cap_rights_contains(const cap_rights_t *big, const cap_rights_t *little); Capability rights to the cap_rights_init(), cap_rights_set(), cap_rights_clear() and cap_rights_is_set() functions are provided by separating them with commas, eg: cap_rights_t rights; cap_rights_init(&rights, CAP_READ, CAP_WRITE, CAP_FSTAT); There is no need to terminate the list of rights, as those functions are actually macros that take care of the termination, eg: #define cap_rights_set(rights, ...) \ __cap_rights_set((rights), __VA_ARGS__, 0ULL) void __cap_rights_set(cap_rights_t *rights, ...); Thanks to using one bit as an array index we can assert in those functions that there are no two rights belonging to different array elements provided together. For example this is illegal and will be detected, because CAP_LOOKUP belongs to element 0 and CAP_PDKILL to element 1: cap_rights_init(&rights, CAP_LOOKUP | CAP_PDKILL); Providing several rights that belongs to the same array's element this way is correct, but is not advised. It should only be used for aliases definition. This commit also breaks compatibility with some existing Capsicum system calls, but I see no other way to do that. This should be fine as Capsicum is still experimental and this change is not going to 9.x. Sponsored by: The FreeBSD Foundation
2013-09-05 00:09:56 +00:00
cap_rights_t rights;
static const unsigned long geomcmds[] = {
DIOCGDELETE,
DIOCGFLUSH
};
PJDLOG_ASSERT(res->hr_role == HAST_ROLE_PRIMARY ||
res->hr_role == HAST_ROLE_SECONDARY);
Change the cap_rights_t type from uint64_t to a structure that we can extend in the future in a backward compatible (API and ABI) way. The cap_rights_t represents capability rights. We used to use one bit to represent one right, but we are running out of spare bits. Currently the new structure provides place for 114 rights (so 50 more than the previous cap_rights_t), but it is possible to grow the structure to hold at least 285 rights, although we can make it even larger if 285 rights won't be enough. The structure definition looks like this: struct cap_rights { uint64_t cr_rights[CAP_RIGHTS_VERSION + 2]; }; The initial CAP_RIGHTS_VERSION is 0. The top two bits in the first element of the cr_rights[] array contain total number of elements in the array - 2. This means if those two bits are equal to 0, we have 2 array elements. The top two bits in all remaining array elements should be 0. The next five bits in all array elements contain array index. Only one bit is used and bit position in this five-bits range defines array index. This means there can be at most five array elements in the future. To define new right the CAPRIGHT() macro must be used. The macro takes two arguments - an array index and a bit to set, eg. #define CAP_PDKILL CAPRIGHT(1, 0x0000000000000800ULL) We still support aliases that combine few rights, but the rights have to belong to the same array element, eg: #define CAP_LOOKUP CAPRIGHT(0, 0x0000000000000400ULL) #define CAP_FCHMOD CAPRIGHT(0, 0x0000000000002000ULL) #define CAP_FCHMODAT (CAP_FCHMOD | CAP_LOOKUP) There is new API to manage the new cap_rights_t structure: cap_rights_t *cap_rights_init(cap_rights_t *rights, ...); void cap_rights_set(cap_rights_t *rights, ...); void cap_rights_clear(cap_rights_t *rights, ...); bool cap_rights_is_set(const cap_rights_t *rights, ...); bool cap_rights_is_valid(const cap_rights_t *rights); void cap_rights_merge(cap_rights_t *dst, const cap_rights_t *src); void cap_rights_remove(cap_rights_t *dst, const cap_rights_t *src); bool cap_rights_contains(const cap_rights_t *big, const cap_rights_t *little); Capability rights to the cap_rights_init(), cap_rights_set(), cap_rights_clear() and cap_rights_is_set() functions are provided by separating them with commas, eg: cap_rights_t rights; cap_rights_init(&rights, CAP_READ, CAP_WRITE, CAP_FSTAT); There is no need to terminate the list of rights, as those functions are actually macros that take care of the termination, eg: #define cap_rights_set(rights, ...) \ __cap_rights_set((rights), __VA_ARGS__, 0ULL) void __cap_rights_set(cap_rights_t *rights, ...); Thanks to using one bit as an array index we can assert in those functions that there are no two rights belonging to different array elements provided together. For example this is illegal and will be detected, because CAP_LOOKUP belongs to element 0 and CAP_PDKILL to element 1: cap_rights_init(&rights, CAP_LOOKUP | CAP_PDKILL); Providing several rights that belongs to the same array's element this way is correct, but is not advised. It should only be used for aliases definition. This commit also breaks compatibility with some existing Capsicum system calls, but I see no other way to do that. This should be fine as Capsicum is still experimental and this change is not going to 9.x. Sponsored by: The FreeBSD Foundation
2013-09-05 00:09:56 +00:00
cap_rights_init(&rights, CAP_FLOCK, CAP_IOCTL, CAP_PREAD,
CAP_PWRITE);
if (cap_rights_limit(res->hr_localfd, &rights) == -1) {
pjdlog_errno(LOG_ERR,
"Unable to limit capability rights on local descriptor");
}
if (cap_ioctls_limit(res->hr_localfd, geomcmds,
sizeof(geomcmds) / sizeof(geomcmds[0])) == -1) {
pjdlog_errno(LOG_ERR,
"Unable to limit allowed GEOM ioctls");
}
if (res->hr_role == HAST_ROLE_PRIMARY) {
static const unsigned long ggatecmds[] = {
G_GATE_CMD_MODIFY,
G_GATE_CMD_START,
G_GATE_CMD_DONE,
G_GATE_CMD_DESTROY
};
Change the cap_rights_t type from uint64_t to a structure that we can extend in the future in a backward compatible (API and ABI) way. The cap_rights_t represents capability rights. We used to use one bit to represent one right, but we are running out of spare bits. Currently the new structure provides place for 114 rights (so 50 more than the previous cap_rights_t), but it is possible to grow the structure to hold at least 285 rights, although we can make it even larger if 285 rights won't be enough. The structure definition looks like this: struct cap_rights { uint64_t cr_rights[CAP_RIGHTS_VERSION + 2]; }; The initial CAP_RIGHTS_VERSION is 0. The top two bits in the first element of the cr_rights[] array contain total number of elements in the array - 2. This means if those two bits are equal to 0, we have 2 array elements. The top two bits in all remaining array elements should be 0. The next five bits in all array elements contain array index. Only one bit is used and bit position in this five-bits range defines array index. This means there can be at most five array elements in the future. To define new right the CAPRIGHT() macro must be used. The macro takes two arguments - an array index and a bit to set, eg. #define CAP_PDKILL CAPRIGHT(1, 0x0000000000000800ULL) We still support aliases that combine few rights, but the rights have to belong to the same array element, eg: #define CAP_LOOKUP CAPRIGHT(0, 0x0000000000000400ULL) #define CAP_FCHMOD CAPRIGHT(0, 0x0000000000002000ULL) #define CAP_FCHMODAT (CAP_FCHMOD | CAP_LOOKUP) There is new API to manage the new cap_rights_t structure: cap_rights_t *cap_rights_init(cap_rights_t *rights, ...); void cap_rights_set(cap_rights_t *rights, ...); void cap_rights_clear(cap_rights_t *rights, ...); bool cap_rights_is_set(const cap_rights_t *rights, ...); bool cap_rights_is_valid(const cap_rights_t *rights); void cap_rights_merge(cap_rights_t *dst, const cap_rights_t *src); void cap_rights_remove(cap_rights_t *dst, const cap_rights_t *src); bool cap_rights_contains(const cap_rights_t *big, const cap_rights_t *little); Capability rights to the cap_rights_init(), cap_rights_set(), cap_rights_clear() and cap_rights_is_set() functions are provided by separating them with commas, eg: cap_rights_t rights; cap_rights_init(&rights, CAP_READ, CAP_WRITE, CAP_FSTAT); There is no need to terminate the list of rights, as those functions are actually macros that take care of the termination, eg: #define cap_rights_set(rights, ...) \ __cap_rights_set((rights), __VA_ARGS__, 0ULL) void __cap_rights_set(cap_rights_t *rights, ...); Thanks to using one bit as an array index we can assert in those functions that there are no two rights belonging to different array elements provided together. For example this is illegal and will be detected, because CAP_LOOKUP belongs to element 0 and CAP_PDKILL to element 1: cap_rights_init(&rights, CAP_LOOKUP | CAP_PDKILL); Providing several rights that belongs to the same array's element this way is correct, but is not advised. It should only be used for aliases definition. This commit also breaks compatibility with some existing Capsicum system calls, but I see no other way to do that. This should be fine as Capsicum is still experimental and this change is not going to 9.x. Sponsored by: The FreeBSD Foundation
2013-09-05 00:09:56 +00:00
cap_rights_init(&rights, CAP_IOCTL);
if (cap_rights_limit(res->hr_ggatefd, &rights) == -1) {
pjdlog_errno(LOG_ERR,
"Unable to limit capability rights to CAP_IOCTL on ggate descriptor");
}
if (cap_ioctls_limit(res->hr_ggatefd, ggatecmds,
sizeof(ggatecmds) / sizeof(ggatecmds[0])) == -1) {
pjdlog_errno(LOG_ERR,
"Unable to limit allowed ggate ioctls");
}
}
}
#else
capsicum = false;
#endif
/*
* Better be sure that everything succeeded.
*/
PJDLOG_VERIFY(getresuid(&ruid, &euid, &suid) == 0);
PJDLOG_VERIFY(ruid == pw->pw_uid);
PJDLOG_VERIFY(euid == pw->pw_uid);
PJDLOG_VERIFY(suid == pw->pw_uid);
PJDLOG_VERIFY(getresgid(&rgid, &egid, &sgid) == 0);
PJDLOG_VERIFY(rgid == pw->pw_gid);
PJDLOG_VERIFY(egid == pw->pw_gid);
PJDLOG_VERIFY(sgid == pw->pw_gid);
PJDLOG_VERIFY(getgroups(0, NULL) == 1);
PJDLOG_VERIFY(getgroups(1, gidset) == 1);
PJDLOG_VERIFY(gidset[0] == pw->pw_gid);
pjdlog_debug(1,
"Privileges successfully dropped using %s%s+setgid+setuid.",
capsicum ? "capsicum+" : "", jailed ? "jail" : "chroot");
return (0);
}