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-rw-r--r--src/basic/selinux-util.c674
1 files changed, 674 insertions, 0 deletions
diff --git a/src/basic/selinux-util.c b/src/basic/selinux-util.c
new file mode 100644
index 0000000..4989f4f
--- /dev/null
+++ b/src/basic/selinux-util.c
@@ -0,0 +1,674 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <malloc.h>
+#include <stddef.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/un.h>
+#include <syslog.h>
+
+#if HAVE_SELINUX
+#include <selinux/avc.h>
+#include <selinux/context.h>
+#include <selinux/label.h>
+#include <selinux/selinux.h>
+#endif
+
+#include "alloc-util.h"
+#include "errno-util.h"
+#include "fd-util.h"
+#include "log.h"
+#include "macro.h"
+#include "path-util.h"
+#include "selinux-util.h"
+#include "stdio-util.h"
+#include "time-util.h"
+
+#if HAVE_SELINUX
+DEFINE_TRIVIAL_CLEANUP_FUNC(context_t, context_free);
+#define _cleanup_context_free_ _cleanup_(context_freep)
+
+static int mac_selinux_reload(int seqno);
+
+static int cached_use = -1;
+static bool initialized = false;
+static int (*enforcing_status_func)(void) = security_getenforce;
+static int last_policyload = 0;
+static struct selabel_handle *label_hnd = NULL;
+
+#define log_enforcing(...) \
+ log_full(mac_selinux_enforcing() ? LOG_ERR : LOG_WARNING, __VA_ARGS__)
+
+#define log_enforcing_errno(error, ...) \
+ ({ \
+ bool _enforcing = mac_selinux_enforcing(); \
+ int _level = _enforcing ? LOG_ERR : LOG_WARNING; \
+ int _e = (error); \
+ \
+ int _r = (log_get_max_level() >= LOG_PRI(_level)) \
+ ? log_internal_realm(_level, _e, PROJECT_FILE, __LINE__, __func__, __VA_ARGS__) \
+ : -ERRNO_VALUE(_e); \
+ _enforcing ? _r : 0; \
+ })
+#endif
+
+bool mac_selinux_use(void) {
+#if HAVE_SELINUX
+ if (_unlikely_(cached_use < 0)) {
+ cached_use = is_selinux_enabled() > 0;
+ log_debug("SELinux enabled state cached to: %s", cached_use ? "enabled" : "disabled");
+ }
+
+ return cached_use;
+#else
+ return false;
+#endif
+}
+
+bool mac_selinux_enforcing(void) {
+#if HAVE_SELINUX
+ return enforcing_status_func() != 0;
+#else
+ return false;
+#endif
+}
+
+void mac_selinux_retest(void) {
+#if HAVE_SELINUX
+ cached_use = -1;
+#endif
+}
+
+#if HAVE_SELINUX
+# if HAVE_MALLINFO
+static struct mallinfo mallinfo_nowarn(void) {
+ /* glibc has deprecated mallinfo(), but the replacement malloc_info() returns an XML blob ;=[ */
+DISABLE_WARNING_DEPRECATED_DECLARATIONS
+ return mallinfo();
+REENABLE_WARNING
+}
+# else
+# warning "mallinfo() is missing, add mallinfo2() supported instead."
+# endif
+
+static int open_label_db(void) {
+ struct selabel_handle *hnd;
+ usec_t before_timestamp, after_timestamp;
+ char timespan[FORMAT_TIMESPAN_MAX];
+
+# if HAVE_MALLINFO
+ struct mallinfo before_mallinfo = mallinfo_nowarn();
+# endif
+ before_timestamp = now(CLOCK_MONOTONIC);
+
+ hnd = selabel_open(SELABEL_CTX_FILE, NULL, 0);
+ if (!hnd)
+ return log_enforcing_errno(errno, "Failed to initialize SELinux labeling handle: %m");
+
+ after_timestamp = now(CLOCK_MONOTONIC);
+# if HAVE_MALLINFO
+ struct mallinfo after_mallinfo = mallinfo_nowarn();
+ int 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),
+ DIV_ROUND_UP(l, 1024));
+# else
+ log_debug("Successfully loaded SELinux database in %s.",
+ format_timespan(timespan, sizeof(timespan), after_timestamp - before_timestamp, 0));
+# endif
+
+ /* release memory after measurement */
+ if (label_hnd)
+ selabel_close(label_hnd);
+ label_hnd = TAKE_PTR(hnd);
+
+ return 0;
+}
+#endif
+
+int mac_selinux_init(void) {
+#if HAVE_SELINUX
+ int r;
+ bool have_status_page = false;
+
+ if (initialized)
+ return 0;
+
+ if (!mac_selinux_use())
+ return 0;
+
+ r = selinux_status_open(/* netlink fallback */ 1);
+ if (r < 0) {
+ if (!ERRNO_IS_PRIVILEGE(errno))
+ return log_enforcing_errno(errno, "Failed to open SELinux status page: %m");
+ log_warning_errno(errno, "selinux_status_open() with netlink fallback failed, not checking for policy reloads: %m");
+ } else if (r == 1)
+ log_warning("selinux_status_open() failed to open the status page, using the netlink fallback.");
+ else
+ have_status_page = true;
+
+ r = open_label_db();
+ if (r < 0) {
+ selinux_status_close();
+ return r;
+ }
+
+ /* Save the current policyload sequence number, so mac_selinux_maybe_reload() does not trigger on
+ * first call without any actual change. */
+ last_policyload = selinux_status_policyload();
+
+ if (have_status_page)
+ /* Now that the SELinux status page has been successfully opened, retrieve the enforcing
+ * status over it (to avoid system calls in security_getenforce()). */
+ enforcing_status_func = selinux_status_getenforce;
+
+ initialized = true;
+#endif
+ return 0;
+}
+
+void mac_selinux_maybe_reload(void) {
+#if HAVE_SELINUX
+ int r;
+
+ if (!initialized)
+ return;
+
+ r = selinux_status_updated();
+ if (r < 0)
+ log_debug_errno(errno, "Failed to update SELinux from status page: %m");
+ if (r > 0) {
+ int policyload;
+
+ log_debug("SELinux status page update");
+
+ /* from libselinux > 3.1 callbacks gets automatically called, see
+ https://github.com/SELinuxProject/selinux/commit/05bdc03130d741e53e1fb45a958d0a2c184be503 */
+
+ /* only reload on policy changes, not enforcing status changes */
+ policyload = selinux_status_policyload();
+ if (policyload != last_policyload) {
+ mac_selinux_reload(policyload);
+ last_policyload = policyload;
+ }
+ }
+#endif
+}
+
+void mac_selinux_finish(void) {
+
+#if HAVE_SELINUX
+ if (label_hnd) {
+ selabel_close(label_hnd);
+ label_hnd = NULL;
+ }
+
+ enforcing_status_func = security_getenforce;
+
+ selinux_status_close();
+
+ initialized = false;
+#endif
+}
+
+#if HAVE_SELINUX
+static int mac_selinux_reload(int seqno) {
+ log_debug("SELinux reload %d", seqno);
+
+ (void) open_label_db();
+
+ return 0;
+}
+#endif
+
+int mac_selinux_fix_container(const char *path, const char *inside_path, LabelFixFlags flags) {
+
+ assert(path);
+ assert(inside_path);
+
+#if HAVE_SELINUX
+ _cleanup_close_ int fd = -1;
+
+ /* if mac_selinux_init() wasn't called before we are a NOOP */
+ if (!label_hnd)
+ return 0;
+
+ /* Open the file as O_PATH, to pin it while we determine and adjust the label */
+ fd = open(path, O_NOFOLLOW|O_CLOEXEC|O_PATH);
+ if (fd < 0) {
+ if ((flags & LABEL_IGNORE_ENOENT) && errno == ENOENT)
+ return 0;
+
+ return -errno;
+ }
+
+ return mac_selinux_fix_container_fd(fd, path, inside_path, flags);
+#endif
+
+ return 0;
+}
+
+int mac_selinux_fix_container_fd(int fd, const char *path, const char *inside_path, LabelFixFlags flags) {
+
+ assert(fd >= 0);
+ assert(inside_path);
+
+#if HAVE_SELINUX
+ char procfs_path[STRLEN("/proc/self/fd/") + DECIMAL_STR_MAX(int)];
+ _cleanup_freecon_ char* fcon = NULL;
+ struct stat st;
+ int r;
+
+ /* if mac_selinux_init() wasn't called before we are a NOOP */
+ if (!label_hnd)
+ return 0;
+
+ if (fstat(fd, &st) < 0)
+ return -errno;
+
+ /* Check for policy reload so 'label_hnd' is kept up-to-date by callbacks */
+ mac_selinux_maybe_reload();
+
+ if (selabel_lookup_raw(label_hnd, &fcon, inside_path, st.st_mode) < 0) {
+ /* If there's no label to set, then exit without warning */
+ if (errno == ENOENT)
+ return 0;
+
+ r = -errno;
+ goto fail;
+ }
+
+ xsprintf(procfs_path, "/proc/self/fd/%i", fd);
+ if (setfilecon_raw(procfs_path, fcon) < 0) {
+ _cleanup_freecon_ char *oldcon = NULL;
+
+ /* If the FS doesn't support labels, then exit without warning */
+ if (ERRNO_IS_NOT_SUPPORTED(errno))
+ return 0;
+
+ /* It the FS is read-only and we were told to ignore failures caused by that, suppress error */
+ if (errno == EROFS && (flags & LABEL_IGNORE_EROFS))
+ return 0;
+
+ r = -errno;
+
+ /* If the old label is identical to the new one, suppress any kind of error */
+ if (getfilecon_raw(procfs_path, &oldcon) >= 0 && streq(fcon, oldcon))
+ return 0;
+
+ goto fail;
+ }
+
+ return 0;
+
+fail:
+ return log_enforcing_errno(r, "Unable to fix SELinux security context of %s (%s): %m", strna(path), strna(inside_path));
+#endif
+
+ return 0;
+}
+
+int mac_selinux_apply(const char *path, const char *label) {
+
+ assert(path);
+
+#if HAVE_SELINUX
+ if (!mac_selinux_use())
+ return 0;
+
+ assert(label);
+
+ if (setfilecon(path, label) < 0)
+ return log_enforcing_errno(errno, "Failed to set SELinux security context %s on path %s: %m", label, path);
+#endif
+ return 0;
+}
+
+int mac_selinux_apply_fd(int fd, const char *path, const char *label) {
+
+ assert(fd >= 0);
+
+#if HAVE_SELINUX
+ if (!mac_selinux_use())
+ return 0;
+
+ assert(label);
+
+ if (fsetfilecon(fd, label) < 0)
+ return log_enforcing_errno(errno, "Failed to set SELinux security context %s on path %s: %m", label, strna(path));
+#endif
+ return 0;
+}
+
+int mac_selinux_get_create_label_from_exe(const char *exe, char **label) {
+#if HAVE_SELINUX
+ _cleanup_freecon_ char *mycon = NULL, *fcon = NULL;
+ security_class_t sclass;
+ int r;
+
+ 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");
+ if (sclass == 0)
+ return -ENOSYS;
+
+ r = security_compute_create_raw(mycon, fcon, sclass, label);
+ if (r < 0)
+ return -errno;
+
+ return 0;
+#else
+ return -EOPNOTSUPP;
+#endif
+}
+
+int mac_selinux_get_our_label(char **label) {
+#if HAVE_SELINUX
+ int r;
+
+ assert(label);
+
+ if (!mac_selinux_use())
+ return -EOPNOTSUPP;
+
+ r = getcon_raw(label);
+ if (r < 0)
+ return -errno;
+
+ return 0;
+#else
+ return -EOPNOTSUPP;
+#endif
+}
+
+int mac_selinux_get_child_mls_label(int socket_fd, const char *exe, const char *exec_label, char **label) {
+#if HAVE_SELINUX
+ _cleanup_freecon_ char *mycon = NULL, *peercon = NULL, *fcon = NULL;
+ _cleanup_context_free_ context_t pcon = NULL, bcon = NULL;
+ security_class_t sclass;
+ const char *range = NULL;
+ int r;
+
+ 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_raw(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");
+ if (sclass == 0)
+ return -ENOSYS;
+
+ r = security_compute_create_raw(mycon, fcon, sclass, label);
+ if (r < 0)
+ return -errno;
+
+ return 0;
+#else
+ return -EOPNOTSUPP;
+#endif
+}
+
+char* mac_selinux_free(char *label) {
+
+#if HAVE_SELINUX
+ freecon(label);
+#else
+ assert(!label);
+#endif
+
+ return NULL;
+}
+
+#if HAVE_SELINUX
+static int selinux_create_file_prepare_abspath(const char *abspath, mode_t mode) {
+ _cleanup_freecon_ char *filecon = NULL;
+ int r;
+
+ assert(abspath);
+ assert(path_is_absolute(abspath));
+
+ /* Check for policy reload so 'label_hnd' is kept up-to-date by callbacks */
+ mac_selinux_maybe_reload();
+
+ r = selabel_lookup_raw(label_hnd, &filecon, abspath, mode);
+ if (r < 0) {
+ /* No context specified by the policy? Proceed without setting it. */
+ if (errno == ENOENT)
+ return 0;
+
+ return log_enforcing_errno(errno, "Failed to determine SELinux security context for %s: %m", abspath);
+ }
+
+ if (setfscreatecon_raw(filecon) < 0)
+ return log_enforcing_errno(errno, "Failed to set SELinux security context %s for %s: %m", filecon, abspath);
+
+ return 0;
+}
+#endif
+
+int mac_selinux_create_file_prepare_at(int dirfd, const char *path, mode_t mode) {
+#if HAVE_SELINUX
+ _cleanup_free_ char *abspath = NULL;
+ int r;
+
+
+ assert(path);
+
+ if (!label_hnd)
+ return 0;
+
+ if (!path_is_absolute(path)) {
+ _cleanup_free_ char *p = NULL;
+
+ if (dirfd == AT_FDCWD)
+ r = safe_getcwd(&p);
+ else
+ r = fd_get_path(dirfd, &p);
+ if (r < 0)
+ return r;
+
+ path = abspath = path_join(p, path);
+ if (!path)
+ return -ENOMEM;
+ }
+
+ return selinux_create_file_prepare_abspath(path, mode);
+#else
+ return 0;
+#endif
+}
+
+int mac_selinux_create_file_prepare(const char *path, mode_t mode) {
+#if HAVE_SELINUX
+ int r;
+
+ _cleanup_free_ char *abspath = NULL;
+
+ assert(path);
+
+ if (!label_hnd)
+ return 0;
+
+ r = path_make_absolute_cwd(path, &abspath);
+ if (r < 0)
+ return r;
+
+ return selinux_create_file_prepare_abspath(abspath, mode);
+#else
+ return 0;
+#endif
+}
+
+void mac_selinux_create_file_clear(void) {
+
+#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;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-09-30 15:15:28 +0000