selinux-util.c revision 0f4743651081b5367ab06f238827ddfd4da74e74
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
This file is part of systemd.
Copyright 2010 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <errno.h>
#include <malloc.h>
#include <sys/un.h>
#ifdef HAVE_SELINUX
#include <selinux/selinux.h>
#include <selinux/label.h>
#include <selinux/context.h>
#endif
#include "strv.h"
#include "path-util.h"
#include "selinux-util.h"
#ifdef HAVE_SELINUX
DEFINE_TRIVIAL_CLEANUP_FUNC(security_context_t, freecon);
DEFINE_TRIVIAL_CLEANUP_FUNC(context_t, context_free);
#define _cleanup_security_context_free_ _cleanup_(freeconp)
#define _cleanup_context_free_ _cleanup_(context_freep)
static int cached_use = -1;
static struct selabel_handle *label_hnd = NULL;
#define log_enforcing(...) log_full(security_getenforce() == 1 ? LOG_ERR : LOG_DEBUG, __VA_ARGS__)
#endif
bool mac_selinux_use(void) {
#ifdef HAVE_SELINUX
if (cached_use < 0)
cached_use = is_selinux_enabled() > 0;
return cached_use;
#else
return false;
#endif
}
void mac_selinux_retest(void) {
#ifdef HAVE_SELINUX
cached_use = -1;
#endif
}
int mac_selinux_init(const char *prefix) {
int r = 0;
#ifdef HAVE_SELINUX
usec_t before_timestamp, after_timestamp;
struct mallinfo before_mallinfo, after_mallinfo;
if (!mac_selinux_use())
return 0;
if (label_hnd)
return 0;
before_mallinfo = mallinfo();
before_timestamp = now(CLOCK_MONOTONIC);
if (prefix) {
struct selinux_opt options[] = {
{ .type = SELABEL_OPT_SUBSET, .value = prefix },
};
label_hnd = selabel_open(SELABEL_CTX_FILE, options, ELEMENTSOF(options));
} else
label_hnd = selabel_open(SELABEL_CTX_FILE, NULL, 0);
if (!label_hnd) {
log_enforcing("Failed to initialize SELinux context: %m");
r = security_getenforce() == 1 ? -errno : 0;
} else {
char timespan[FORMAT_TIMESPAN_MAX];
int l;
after_timestamp = now(CLOCK_MONOTONIC);
after_mallinfo = mallinfo();
l = after_mallinfo.uordblks > before_mallinfo.uordblks ? after_mallinfo.uordblks - before_mallinfo.uordblks : 0;
log_debug("Successfully loaded SELinux database in %s, size on heap is %iK.",
format_timespan(timespan, sizeof(timespan), after_timestamp - before_timestamp, 0),
(l+1023)/1024);
}
#endif
return r;
}
void mac_selinux_finish(void) {
#ifdef HAVE_SELINUX
if (!label_hnd)
return;
selabel_close(label_hnd);
label_hnd = NULL;
#endif
}
int mac_selinux_fix(const char *path, bool ignore_enoent, bool ignore_erofs) {
#ifdef HAVE_SELINUX
struct stat st;
int r;
assert(path);
/* if mac_selinux_init() wasn't called before we are a NOOP */
if (!label_hnd)
return 0;
r = lstat(path, &st);
if (r >= 0) {
_cleanup_security_context_free_ security_context_t fcon = NULL;
r = selabel_lookup_raw(label_hnd, &fcon, path, st.st_mode);
/* If there's no label to set, then exit without warning */
if (r < 0 && errno == ENOENT)
return 0;
if (r >= 0) {
r = lsetfilecon(path, fcon);
/* If the FS doesn't support labels, then exit without warning */
if (r < 0 && errno == EOPNOTSUPP)
return 0;
}
}
if (r < 0) {
/* Ignore ENOENT in some cases */
if (ignore_enoent && errno == ENOENT)
return 0;
if (ignore_erofs && errno == EROFS)
return 0;
log_enforcing("Unable to fix SELinux security context of %s: %m", path);
if (security_getenforce() == 1)
return -errno;
}
#endif
return 0;
}
int mac_selinux_apply(const char *path, const char *label) {
#ifdef HAVE_SELINUX
if (!mac_selinux_use())
return 0;
assert(path);
assert(label);
if (setfilecon(path, (security_context_t) label) < 0) {
log_enforcing("Failed to set SELinux security context %s on path %s: %m", label, path);
if (security_getenforce() > 0)
return -errno;
}
#endif
return 0;
}
int mac_selinux_get_create_label_from_exe(const char *exe, char **label) {
int r = -EOPNOTSUPP;
#ifdef HAVE_SELINUX
_cleanup_security_context_free_ security_context_t mycon = NULL, fcon = NULL;
security_class_t sclass;
assert(exe);
assert(label);
if (!mac_selinux_use())
return -EOPNOTSUPP;
r = getcon_raw(&mycon);
if (r < 0)
return -errno;
r = getfilecon_raw(exe, &fcon);
if (r < 0)
return -errno;
sclass = string_to_security_class("process");
r = security_compute_create(mycon, fcon, sclass, (security_context_t *) label);
if (r < 0)
return -errno;
#endif
return r;
}
int mac_selinux_get_our_label(char **label) {
int r = -EOPNOTSUPP;
assert(label);
#ifdef HAVE_SELINUX
if (!mac_selinux_use())
return -EOPNOTSUPP;
r = getcon_raw(label);
if (r < 0)
return -errno;
#endif
return r;
}
int mac_selinux_get_child_mls_label(int socket_fd, const char *exe, const char *exec_label, char **label) {
int r = -EOPNOTSUPP;
#ifdef HAVE_SELINUX
_cleanup_security_context_free_ security_context_t mycon = NULL, peercon = NULL, fcon = NULL;
_cleanup_context_free_ context_t pcon = NULL, bcon = NULL;
security_class_t sclass;
const char *range = NULL;
assert(socket_fd >= 0);
assert(exe);
assert(label);
if (!mac_selinux_use())
return -EOPNOTSUPP;
r = getcon_raw(&mycon);
if (r < 0)
return -errno;
r = getpeercon(socket_fd, &peercon);
if (r < 0)
return -errno;
if (!exec_label) {
/* If there is no context set for next exec let's use context
of target executable */
r = getfilecon_raw(exe, &fcon);
if (r < 0)
return -errno;
}
bcon = context_new(mycon);
if (!bcon)
return -ENOMEM;
pcon = context_new(peercon);
if (!pcon)
return -ENOMEM;
range = context_range_get(pcon);
if (!range)
return -errno;
r = context_range_set(bcon, range);
if (r)
return -errno;
freecon(mycon);
mycon = strdup(context_str(bcon));
if (!mycon)
return -ENOMEM;
sclass = string_to_security_class("process");
r = security_compute_create(mycon, fcon, sclass, (security_context_t *) label);
if (r < 0)
return -errno;
#endif
return r;
}
char* mac_selinux_free(char *label) {
#ifdef HAVE_SELINUX
if (!label)
return NULL;
if (!mac_selinux_use())
return NULL;
freecon((security_context_t) label);
#endif
return NULL;
}
int mac_selinux_create_file_prepare(const char *path, mode_t mode) {
#ifdef HAVE_SELINUX
_cleanup_security_context_free_ security_context_t filecon = NULL;
int r;
assert(path);
if (!label_hnd)
return 0;
if (path_is_absolute(path))
r = selabel_lookup_raw(label_hnd, &filecon, path, mode);
else {
_cleanup_free_ char *newpath = NULL;
r = path_make_absolute_cwd(path, &newpath);
if (r < 0)
return r;
r = selabel_lookup_raw(label_hnd, &filecon, newpath, mode);
}
if (r < 0) {
/* No context specified by the policy? Proceed without setting it. */
if (errno == ENOENT)
return 0;
log_enforcing("Failed to determine SELinux security context for %s: %m", path);
} else {
if (setfscreatecon(filecon) >= 0)
return 0; /* Success! */
log_enforcing("Failed to set SELinux security context %s for %s: %m", filecon, path);
}
if (security_getenforce() > 0)
return -errno;
#endif
return 0;
}
void mac_selinux_create_file_clear(void) {
#ifdef HAVE_SELINUX
PROTECT_ERRNO;
if (!mac_selinux_use())
return;
setfscreatecon(NULL);
#endif
}
int mac_selinux_create_socket_prepare(const char *label) {
#ifdef HAVE_SELINUX
if (!mac_selinux_use())
return 0;
assert(label);
if (setsockcreatecon((security_context_t) label) < 0) {
log_enforcing("Failed to set SELinux security context %s for sockets: %m", label);
if (security_getenforce() == 1)
return -errno;
}
#endif
return 0;
}
void mac_selinux_create_socket_clear(void) {
#ifdef HAVE_SELINUX
PROTECT_ERRNO;
if (!mac_selinux_use())
return;
setsockcreatecon(NULL);
#endif
}
int mac_selinux_bind(int fd, const struct sockaddr *addr, socklen_t addrlen) {
/* Binds a socket and label its file system object according to the SELinux policy */
#ifdef HAVE_SELINUX
_cleanup_security_context_free_ security_context_t fcon = NULL;
const struct sockaddr_un *un;
bool context_changed = false;
char *path;
int r;
assert(fd >= 0);
assert(addr);
assert(addrlen >= sizeof(sa_family_t));
if (!label_hnd)
goto skipped;
/* Filter out non-local sockets */
if (addr->sa_family != AF_UNIX)
goto skipped;
/* Filter out anonymous sockets */
if (addrlen < offsetof(struct sockaddr_un, sun_path) + 1)
goto skipped;
/* Filter out abstract namespace sockets */
un = (const struct sockaddr_un*) addr;
if (un->sun_path[0] == 0)
goto skipped;
path = strndupa(un->sun_path, addrlen - offsetof(struct sockaddr_un, sun_path));
if (path_is_absolute(path))
r = selabel_lookup_raw(label_hnd, &fcon, path, S_IFSOCK);
else {
_cleanup_free_ char *newpath = NULL;
r = path_make_absolute_cwd(path, &newpath);
if (r < 0)
return r;
r = selabel_lookup_raw(label_hnd, &fcon, newpath, S_IFSOCK);
}
if (r < 0) {
/* No context specified by the policy? Proceed without setting it */
if (errno == ENOENT)
goto skipped;
log_enforcing("Failed to determine SELinux security context for %s: %m", path);
if (security_getenforce() > 0)
return -errno;
} else {
if (setfscreatecon(fcon) < 0) {
log_enforcing("Failed to set SELinux security context %s for %s: %m", fcon, path);
if (security_getenforce() > 0)
return -errno;
} else
context_changed = true;
}
r = bind(fd, addr, addrlen) < 0 ? -errno : 0;
if (context_changed)
setfscreatecon(NULL);
return r;
skipped:
#endif
if (bind(fd, addr, addrlen) < 0)
return -errno;
return 0;
}