675 lines
18 KiB
C
675 lines
18 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#include <errno.h>
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#include <fcntl.h>
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#include <malloc.h>
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#include <stddef.h>
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#include <string.h>
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#include <sys/stat.h>
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#include <sys/time.h>
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#include <sys/types.h>
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#include <sys/un.h>
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#include <syslog.h>
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#if HAVE_SELINUX
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#include <selinux/avc.h>
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#include <selinux/context.h>
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#include <selinux/label.h>
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#include <selinux/selinux.h>
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#endif
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#include "alloc-util.h"
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#include "errno-util.h"
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#include "fd-util.h"
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#include "log.h"
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#include "macro.h"
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#include "path-util.h"
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#include "selinux-util.h"
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#include "stdio-util.h"
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#include "time-util.h"
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#if HAVE_SELINUX
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DEFINE_TRIVIAL_CLEANUP_FUNC(context_t, context_free);
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#define _cleanup_context_free_ _cleanup_(context_freep)
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static int mac_selinux_reload(int seqno);
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static int cached_use = -1;
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static bool initialized = false;
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static int (*enforcing_status_func)(void) = security_getenforce;
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static int last_policyload = 0;
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static struct selabel_handle *label_hnd = NULL;
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#define log_enforcing(...) \
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log_full(mac_selinux_enforcing() ? LOG_ERR : LOG_WARNING, __VA_ARGS__)
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#define log_enforcing_errno(error, ...) \
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({ \
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bool _enforcing = mac_selinux_enforcing(); \
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int _level = _enforcing ? LOG_ERR : LOG_WARNING; \
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int _e = (error); \
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\
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int _r = (log_get_max_level() >= LOG_PRI(_level)) \
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? log_internal_realm(_level, _e, PROJECT_FILE, __LINE__, __func__, __VA_ARGS__) \
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: -ERRNO_VALUE(_e); \
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_enforcing ? _r : 0; \
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})
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#endif
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bool mac_selinux_use(void) {
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#if HAVE_SELINUX
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if (_unlikely_(cached_use < 0)) {
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cached_use = is_selinux_enabled() > 0;
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log_debug("SELinux enabled state cached to: %s", cached_use ? "enabled" : "disabled");
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}
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return cached_use;
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#else
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return false;
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#endif
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}
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bool mac_selinux_enforcing(void) {
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#if HAVE_SELINUX
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return enforcing_status_func() != 0;
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#else
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return false;
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#endif
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}
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void mac_selinux_retest(void) {
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#if HAVE_SELINUX
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cached_use = -1;
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#endif
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}
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#if HAVE_SELINUX
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# if HAVE_MALLINFO
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static struct mallinfo mallinfo_nowarn(void) {
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/* glibc has deprecated mallinfo(), but the replacement malloc_info() returns an XML blob ;=[ */
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DISABLE_WARNING_DEPRECATED_DECLARATIONS
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return mallinfo();
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REENABLE_WARNING
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}
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# else
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# warning "mallinfo() is missing, add mallinfo2() supported instead."
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# endif
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static int open_label_db(void) {
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struct selabel_handle *hnd;
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usec_t before_timestamp, after_timestamp;
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char timespan[FORMAT_TIMESPAN_MAX];
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# if HAVE_MALLINFO
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struct mallinfo before_mallinfo = mallinfo_nowarn();
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# endif
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before_timestamp = now(CLOCK_MONOTONIC);
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hnd = selabel_open(SELABEL_CTX_FILE, NULL, 0);
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if (!hnd)
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return log_enforcing_errno(errno, "Failed to initialize SELinux labeling handle: %m");
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after_timestamp = now(CLOCK_MONOTONIC);
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# if HAVE_MALLINFO
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struct mallinfo after_mallinfo = mallinfo_nowarn();
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int l = after_mallinfo.uordblks > before_mallinfo.uordblks ? after_mallinfo.uordblks - before_mallinfo.uordblks : 0;
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log_debug("Successfully loaded SELinux database in %s, size on heap is %iK.",
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format_timespan(timespan, sizeof(timespan), after_timestamp - before_timestamp, 0),
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DIV_ROUND_UP(l, 1024));
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# else
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log_debug("Successfully loaded SELinux database in %s.",
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format_timespan(timespan, sizeof(timespan), after_timestamp - before_timestamp, 0));
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# endif
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/* release memory after measurement */
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if (label_hnd)
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selabel_close(label_hnd);
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label_hnd = TAKE_PTR(hnd);
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return 0;
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}
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#endif
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int mac_selinux_init(void) {
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#if HAVE_SELINUX
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int r;
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bool have_status_page = false;
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if (initialized)
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return 0;
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if (!mac_selinux_use())
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return 0;
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r = selinux_status_open(/* netlink fallback */ 1);
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if (r < 0) {
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if (!ERRNO_IS_PRIVILEGE(errno))
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return log_enforcing_errno(errno, "Failed to open SELinux status page: %m");
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log_warning_errno(errno, "selinux_status_open() with netlink fallback failed, not checking for policy reloads: %m");
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} else if (r == 1)
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log_warning("selinux_status_open() failed to open the status page, using the netlink fallback.");
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else
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have_status_page = true;
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r = open_label_db();
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if (r < 0) {
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selinux_status_close();
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return r;
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}
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/* Save the current policyload sequence number, so mac_selinux_maybe_reload() does not trigger on
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* first call without any actual change. */
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last_policyload = selinux_status_policyload();
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if (have_status_page)
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/* Now that the SELinux status page has been successfully opened, retrieve the enforcing
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* status over it (to avoid system calls in security_getenforce()). */
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enforcing_status_func = selinux_status_getenforce;
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initialized = true;
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#endif
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return 0;
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}
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void mac_selinux_maybe_reload(void) {
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#if HAVE_SELINUX
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int r;
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if (!initialized)
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return;
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r = selinux_status_updated();
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if (r < 0)
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log_debug_errno(errno, "Failed to update SELinux from status page: %m");
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if (r > 0) {
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int policyload;
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log_debug("SELinux status page update");
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/* from libselinux > 3.1 callbacks gets automatically called, see
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https://github.com/SELinuxProject/selinux/commit/05bdc03130d741e53e1fb45a958d0a2c184be503 */
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/* only reload on policy changes, not enforcing status changes */
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policyload = selinux_status_policyload();
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if (policyload != last_policyload) {
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mac_selinux_reload(policyload);
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last_policyload = policyload;
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}
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}
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#endif
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}
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void mac_selinux_finish(void) {
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#if HAVE_SELINUX
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if (label_hnd) {
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selabel_close(label_hnd);
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label_hnd = NULL;
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}
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enforcing_status_func = security_getenforce;
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selinux_status_close();
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initialized = false;
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#endif
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}
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#if HAVE_SELINUX
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static int mac_selinux_reload(int seqno) {
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log_debug("SELinux reload %d", seqno);
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(void) open_label_db();
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return 0;
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}
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#endif
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int mac_selinux_fix_container(const char *path, const char *inside_path, LabelFixFlags flags) {
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assert(path);
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assert(inside_path);
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#if HAVE_SELINUX
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_cleanup_close_ int fd = -1;
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/* if mac_selinux_init() wasn't called before we are a NOOP */
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if (!label_hnd)
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return 0;
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/* Open the file as O_PATH, to pin it while we determine and adjust the label */
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fd = open(path, O_NOFOLLOW|O_CLOEXEC|O_PATH);
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if (fd < 0) {
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if ((flags & LABEL_IGNORE_ENOENT) && errno == ENOENT)
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return 0;
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return -errno;
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}
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return mac_selinux_fix_container_fd(fd, path, inside_path, flags);
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#endif
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return 0;
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}
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int mac_selinux_fix_container_fd(int fd, const char *path, const char *inside_path, LabelFixFlags flags) {
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assert(fd >= 0);
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assert(inside_path);
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#if HAVE_SELINUX
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char procfs_path[STRLEN("/proc/self/fd/") + DECIMAL_STR_MAX(int)];
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_cleanup_freecon_ char* fcon = NULL;
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struct stat st;
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int r;
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/* if mac_selinux_init() wasn't called before we are a NOOP */
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if (!label_hnd)
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return 0;
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if (fstat(fd, &st) < 0)
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return -errno;
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/* Check for policy reload so 'label_hnd' is kept up-to-date by callbacks */
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mac_selinux_maybe_reload();
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if (selabel_lookup_raw(label_hnd, &fcon, inside_path, st.st_mode) < 0) {
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/* If there's no label to set, then exit without warning */
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if (errno == ENOENT)
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return 0;
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r = -errno;
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goto fail;
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}
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xsprintf(procfs_path, "/proc/self/fd/%i", fd);
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if (setfilecon_raw(procfs_path, fcon) < 0) {
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_cleanup_freecon_ char *oldcon = NULL;
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/* If the FS doesn't support labels, then exit without warning */
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if (ERRNO_IS_NOT_SUPPORTED(errno))
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return 0;
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/* It the FS is read-only and we were told to ignore failures caused by that, suppress error */
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if (errno == EROFS && (flags & LABEL_IGNORE_EROFS))
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return 0;
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r = -errno;
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/* If the old label is identical to the new one, suppress any kind of error */
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if (getfilecon_raw(procfs_path, &oldcon) >= 0 && streq(fcon, oldcon))
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return 0;
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goto fail;
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}
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return 0;
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fail:
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return log_enforcing_errno(r, "Unable to fix SELinux security context of %s (%s): %m", strna(path), strna(inside_path));
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#endif
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return 0;
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}
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int mac_selinux_apply(const char *path, const char *label) {
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assert(path);
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#if HAVE_SELINUX
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if (!mac_selinux_use())
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return 0;
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assert(label);
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if (setfilecon(path, label) < 0)
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return log_enforcing_errno(errno, "Failed to set SELinux security context %s on path %s: %m", label, path);
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#endif
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return 0;
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}
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int mac_selinux_apply_fd(int fd, const char *path, const char *label) {
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assert(fd >= 0);
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#if HAVE_SELINUX
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if (!mac_selinux_use())
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return 0;
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assert(label);
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if (fsetfilecon(fd, label) < 0)
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return log_enforcing_errno(errno, "Failed to set SELinux security context %s on path %s: %m", label, strna(path));
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#endif
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return 0;
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}
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int mac_selinux_get_create_label_from_exe(const char *exe, char **label) {
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#if HAVE_SELINUX
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_cleanup_freecon_ char *mycon = NULL, *fcon = NULL;
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security_class_t sclass;
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int r;
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assert(exe);
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assert(label);
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if (!mac_selinux_use())
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return -EOPNOTSUPP;
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r = getcon_raw(&mycon);
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if (r < 0)
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return -errno;
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r = getfilecon_raw(exe, &fcon);
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if (r < 0)
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return -errno;
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sclass = string_to_security_class("process");
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if (sclass == 0)
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return -ENOSYS;
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r = security_compute_create_raw(mycon, fcon, sclass, label);
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if (r < 0)
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return -errno;
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return 0;
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#else
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return -EOPNOTSUPP;
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#endif
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}
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int mac_selinux_get_our_label(char **label) {
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#if HAVE_SELINUX
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int r;
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assert(label);
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if (!mac_selinux_use())
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return -EOPNOTSUPP;
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r = getcon_raw(label);
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if (r < 0)
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return -errno;
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return 0;
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#else
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return -EOPNOTSUPP;
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#endif
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}
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int mac_selinux_get_child_mls_label(int socket_fd, const char *exe, const char *exec_label, char **label) {
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#if HAVE_SELINUX
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_cleanup_freecon_ char *mycon = NULL, *peercon = NULL, *fcon = NULL;
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_cleanup_context_free_ context_t pcon = NULL, bcon = NULL;
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security_class_t sclass;
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const char *range = NULL;
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int r;
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assert(socket_fd >= 0);
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assert(exe);
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assert(label);
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if (!mac_selinux_use())
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return -EOPNOTSUPP;
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r = getcon_raw(&mycon);
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if (r < 0)
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return -errno;
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r = getpeercon_raw(socket_fd, &peercon);
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if (r < 0)
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return -errno;
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if (!exec_label) {
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/* If there is no context set for next exec let's use context
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of target executable */
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r = getfilecon_raw(exe, &fcon);
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if (r < 0)
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return -errno;
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}
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bcon = context_new(mycon);
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if (!bcon)
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return -ENOMEM;
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pcon = context_new(peercon);
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if (!pcon)
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return -ENOMEM;
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range = context_range_get(pcon);
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if (!range)
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return -errno;
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r = context_range_set(bcon, range);
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if (r)
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return -errno;
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freecon(mycon);
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mycon = strdup(context_str(bcon));
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if (!mycon)
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return -ENOMEM;
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sclass = string_to_security_class("process");
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if (sclass == 0)
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return -ENOSYS;
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r = security_compute_create_raw(mycon, fcon, sclass, label);
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if (r < 0)
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return -errno;
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return 0;
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#else
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return -EOPNOTSUPP;
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#endif
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}
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char* mac_selinux_free(char *label) {
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#if HAVE_SELINUX
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freecon(label);
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#else
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assert(!label);
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#endif
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return NULL;
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}
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#if HAVE_SELINUX
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static int selinux_create_file_prepare_abspath(const char *abspath, mode_t mode) {
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_cleanup_freecon_ char *filecon = NULL;
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int r;
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assert(abspath);
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assert(path_is_absolute(abspath));
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/* Check for policy reload so 'label_hnd' is kept up-to-date by callbacks */
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mac_selinux_maybe_reload();
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r = selabel_lookup_raw(label_hnd, &filecon, abspath, mode);
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if (r < 0) {
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/* No context specified by the policy? Proceed without setting it. */
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if (errno == ENOENT)
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return 0;
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return log_enforcing_errno(errno, "Failed to determine SELinux security context for %s: %m", abspath);
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}
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if (setfscreatecon_raw(filecon) < 0)
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return log_enforcing_errno(errno, "Failed to set SELinux security context %s for %s: %m", filecon, abspath);
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return 0;
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}
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#endif
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int mac_selinux_create_file_prepare_at(int dirfd, const char *path, mode_t mode) {
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#if HAVE_SELINUX
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_cleanup_free_ char *abspath = NULL;
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int r;
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assert(path);
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if (!label_hnd)
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return 0;
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if (!path_is_absolute(path)) {
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_cleanup_free_ char *p = NULL;
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if (dirfd == AT_FDCWD)
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r = safe_getcwd(&p);
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else
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r = fd_get_path(dirfd, &p);
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if (r < 0)
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return r;
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path = abspath = path_join(p, path);
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if (!path)
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return -ENOMEM;
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}
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return selinux_create_file_prepare_abspath(path, mode);
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#else
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return 0;
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#endif
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}
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int mac_selinux_create_file_prepare(const char *path, mode_t mode) {
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#if HAVE_SELINUX
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int r;
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_cleanup_free_ char *abspath = NULL;
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assert(path);
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if (!label_hnd)
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return 0;
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r = path_make_absolute_cwd(path, &abspath);
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if (r < 0)
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return r;
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return selinux_create_file_prepare_abspath(abspath, mode);
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#else
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return 0;
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#endif
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}
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void mac_selinux_create_file_clear(void) {
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#if HAVE_SELINUX
|
|
PROTECT_ERRNO;
|
|
|
|
if (!mac_selinux_use())
|
|
return;
|
|
|
|
setfscreatecon_raw(NULL);
|
|
#endif
|
|
}
|
|
|
|
int mac_selinux_create_socket_prepare(const char *label) {
|
|
|
|
#if HAVE_SELINUX
|
|
assert(label);
|
|
|
|
if (!mac_selinux_use())
|
|
return 0;
|
|
|
|
if (setsockcreatecon(label) < 0)
|
|
return log_enforcing_errno(errno, "Failed to set SELinux security context %s for sockets: %m", label);
|
|
#endif
|
|
|
|
return 0;
|
|
}
|
|
|
|
void mac_selinux_create_socket_clear(void) {
|
|
|
|
#if HAVE_SELINUX
|
|
PROTECT_ERRNO;
|
|
|
|
if (!mac_selinux_use())
|
|
return;
|
|
|
|
setsockcreatecon_raw(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 */
|
|
|
|
#if HAVE_SELINUX
|
|
_cleanup_freecon_ char *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));
|
|
|
|
/* Check for policy reload so 'label_hnd' is kept up-to-date by callbacks */
|
|
mac_selinux_maybe_reload();
|
|
|
|
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;
|
|
|
|
r = log_enforcing_errno(errno, "Failed to determine SELinux security context for %s: %m", path);
|
|
if (r < 0)
|
|
return r;
|
|
} else {
|
|
if (setfscreatecon_raw(fcon) < 0) {
|
|
r = log_enforcing_errno(errno, "Failed to set SELinux security context %s for %s: %m", fcon, path);
|
|
if (r < 0)
|
|
return r;
|
|
} else
|
|
context_changed = true;
|
|
}
|
|
|
|
r = bind(fd, addr, addrlen) < 0 ? -errno : 0;
|
|
|
|
if (context_changed)
|
|
(void) setfscreatecon_raw(NULL);
|
|
|
|
return r;
|
|
|
|
skipped:
|
|
#endif
|
|
if (bind(fd, addr, addrlen) < 0)
|
|
return -errno;
|
|
|
|
return 0;
|
|
}
|