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b9c1bc28eb
systemd/src/shared/label.c
Łukasz Stelmach b9c1bc28eb smack: rework security labeling for multiple frameworks
2014-02-24 17:37:41 +01:00

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/*-*- 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 <unistd.h>
#include <malloc.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#ifdef HAVE_XATTR
#include <sys/xattr.h>
#endif
#ifdef HAVE_SELINUX
#include <selinux/selinux.h>
#include <selinux/label.h>
#endif
#include "label.h"
#include "strv.h"
#include "util.h"
#include "path-util.h"
#include "selinux-util.h"
#include "smack-util.h"
#ifdef HAVE_SELINUX
static struct selabel_handle *label_hnd = NULL;
#endif
static int smack_relabel_in_dev(const char *path) {
int r = 0;
#ifdef HAVE_SMACK
struct stat sb;
const char *label;
/*
* Path must be in /dev and must exist
*/
if (!path_startswith(path, "/dev"))
return 0;
r = lstat(path, &sb);
if (r < 0)
return -errno;
/*
* Label directories and character devices "*".
* Label symlinks "_".
* Don't change anything else.
*/
if (S_ISDIR(sb.st_mode))
label = SMACK_STAR_LABEL;
else if (S_ISLNK(sb.st_mode))
label = SMACK_FLOOR_LABEL;
else if (S_ISCHR(sb.st_mode))
label = SMACK_STAR_LABEL;
else
return 0;
r = setxattr(path, "security.SMACK64", label, strlen(label), 0);
if (r < 0) {
log_error("Smack relabeling \"%s\" %s", path, strerror(errno));
return -errno;
}
#endif
return r;
}
int label_init(const char *prefix) {
int r = 0;
#ifdef HAVE_SELINUX
usec_t before_timestamp, after_timestamp;
struct mallinfo before_mallinfo, after_mallinfo;
if (!use_selinux())
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_full(security_getenforce() == 1 ? LOG_ERR : LOG_DEBUG,
"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;
}
static int label_fix_selinux(const char *path, bool ignore_enoent, bool ignore_erofs) {
int r = 0;
#ifdef HAVE_SELINUX
struct stat st;
security_context_t fcon;
if (!label_hnd)
return 0;
r = lstat(path, &st);
if (r == 0) {
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);
freecon(fcon);
/* If the FS doesn't support labels, then exit without warning */
if (r < 0 && errno == ENOTSUP)
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_full(security_getenforce() == 1 ? LOG_ERR : LOG_DEBUG,
"Unable to fix label of %s: %m", path);
r = security_getenforce() == 1 ? -errno : 0;
}
#endif
return r;
}
int label_fix(const char *path, bool ignore_enoent, bool ignore_erofs) {
int r = 0;
if (use_selinux()) {
r = label_fix_selinux(path, ignore_enoent, ignore_erofs);
if (r < 0)
return r;
}
if (use_smack()) {
r = smack_relabel_in_dev(path);
if (r < 0)
return r;
}
return r;
}
void label_finish(void) {
#ifdef HAVE_SELINUX
if (!use_selinux())
return;
if (label_hnd)
selabel_close(label_hnd);
#endif
}
int label_get_create_label_from_exe(const char *exe, char **label) {
int r = 0;
#ifdef HAVE_SELINUX
security_context_t mycon = NULL, fcon = NULL;
security_class_t sclass;
if (!use_selinux()) {
*label = NULL;
return 0;
}
r = getcon(&mycon);
if (r < 0)
goto fail;
r = getfilecon(exe, &fcon);
if (r < 0)
goto fail;
sclass = string_to_security_class("process");
r = security_compute_create(mycon, fcon, sclass, (security_context_t *) label);
if (r == 0)
log_debug("SELinux Socket context for %s will be set to %s", exe, *label);
fail:
if (r < 0 && security_getenforce() == 1)
r = -errno;
freecon(mycon);
freecon(fcon);
#endif
return r;
}
int label_context_set(const char *path, mode_t mode) {
int r = 0;
#ifdef HAVE_SELINUX
security_context_t filecon = NULL;
if (!use_selinux() || !label_hnd)
return 0;
r = selabel_lookup_raw(label_hnd, &filecon, path, mode);
if (r < 0 && errno != ENOENT)
r = -errno;
else if (r == 0) {
r = setfscreatecon(filecon);
if (r < 0) {
log_error("Failed to set SELinux file context on %s: %m", path);
r = -errno;
}
freecon(filecon);
}
if (r < 0 && security_getenforce() == 0)
r = 0;
#endif
return r;
}
int label_socket_set(const char *label) {
#ifdef HAVE_SELINUX
if (!use_selinux())
return 0;
if (setsockcreatecon((security_context_t) label) < 0) {
log_full(security_getenforce() == 1 ? LOG_ERR : LOG_DEBUG,
"Failed to set SELinux context (%s) on socket: %m", label);
if (security_getenforce() == 1)
return -errno;
}
#endif
return 0;
}
void label_context_clear(void) {
#ifdef HAVE_SELINUX
if (!use_selinux())
return;
setfscreatecon(NULL);
#endif
}
void label_socket_clear(void) {
#ifdef HAVE_SELINUX
if (!use_selinux())
return;
setsockcreatecon(NULL);
#endif
}
void label_free(const char *label) {
#ifdef HAVE_SELINUX
if (!use_selinux())
return;
freecon((security_context_t) label);
#endif
}
static int label_mkdir_selinux(const char *path, mode_t mode) {
int r = 0;
#ifdef HAVE_SELINUX
/* Creates a directory and labels it according to the SELinux policy */
security_context_t fcon = NULL;
if (!label_hnd)
return 0;
if (path_is_absolute(path))
r = selabel_lookup_raw(label_hnd, &fcon, path, S_IFDIR);
else {
_cleanup_free_ char *newpath;
newpath = path_make_absolute_cwd(path);
if (!newpath)
return -ENOMEM;
r = selabel_lookup_raw(label_hnd, &fcon, newpath, S_IFDIR);
}
if (r == 0)
r = setfscreatecon(fcon);
if (r < 0 && errno != ENOENT) {
log_error("Failed to set security context %s for %s: %m", fcon, path);
if (security_getenforce() == 1) {
r = -errno;
goto finish;
}
}
r = mkdir(path, mode);
if (r < 0)
r = -errno;
finish:
setfscreatecon(NULL);
freecon(fcon);
#endif
return r;
}
int label_mkdir(const char *path, mode_t mode) {
int r;
if (use_selinux()) {
r = label_mkdir_selinux(path, mode);
if (r < 0)
return r;
}
if (use_smack()) {
r = mkdir(path, mode);
if (r < 0 && errno != EEXIST)
return -errno;
r = smack_relabel_in_dev(path);
if (r < 0)
return r;
}
r = mkdir(path, mode);
if (r < 0 && errno != EEXIST)
return -errno;
return 0;
}
int label_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
security_context_t fcon = NULL;
const struct sockaddr_un *un;
char *path;
int r;
assert(fd >= 0);
assert(addr);
assert(addrlen >= sizeof(sa_family_t));
if (!use_selinux() || !label_hnd)
goto skipped;
/* Filter out non-local sockets */
if (addr->sa_family != AF_UNIX)
goto skipped;
/* Filter out anonymous sockets */
if (addrlen < sizeof(sa_family_t) + 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;
newpath = path_make_absolute_cwd(path);
if (!newpath)
return -ENOMEM;
r = selabel_lookup_raw(label_hnd, &fcon, newpath, S_IFSOCK);
}
if (r == 0)
r = setfscreatecon(fcon);
if (r < 0 && errno != ENOENT) {
log_error("Failed to set security context %s for %s: %m", fcon, path);
if (security_getenforce() == 1) {
r = -errno;
goto finish;
}
}
r = bind(fd, addr, addrlen);
if (r < 0)
r = -errno;
finish:
setfscreatecon(NULL);
freecon(fcon);
return r;
skipped:
#endif
return bind(fd, addr, addrlen) < 0 ? -errno : 0;
}
int label_apply(const char *path, const char *label) {
int r = 0;
#ifdef HAVE_SELINUX
if (!use_selinux())
return 0;
r = setfilecon(path, (char *)label);
#endif
return r;
}
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