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-rw-r--r--src/basic/selinux-util.c518
1 files changed, 518 insertions, 0 deletions
diff --git a/src/basic/selinux-util.c b/src/basic/selinux-util.c
new file mode 100644
index 0000000..dc06f3d
--- /dev/null
+++ b/src/basic/selinux-util.c
@@ -0,0 +1,518 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include <errno.h>
+#include <malloc.h>
+#include <stddef.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/time.h>
+#include <sys/un.h>
+#include <syslog.h>
+
+#if HAVE_SELINUX
+#include <selinux/context.h>
+#include <selinux/label.h>
+#include <selinux/selinux.h>
+#endif
+
+#include "alloc-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"
+#include "util.h"
+
+#if HAVE_SELINUX
+DEFINE_TRIVIAL_CLEANUP_FUNC(char*, freecon);
+DEFINE_TRIVIAL_CLEANUP_FUNC(context_t, context_free);
+
+#define _cleanup_freecon_ _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__)
+#define log_enforcing_errno(r, ...) log_full_errno(security_getenforce() == 1 ? LOG_ERR : LOG_DEBUG, r, __VA_ARGS__)
+#endif
+
+bool mac_selinux_use(void) {
+#if HAVE_SELINUX
+ if (cached_use < 0)
+ cached_use = is_selinux_enabled() > 0;
+
+ return cached_use;
+#else
+ return false;
+#endif
+}
+
+void mac_selinux_retest(void) {
+#if HAVE_SELINUX
+ cached_use = -1;
+#endif
+}
+
+int mac_selinux_init(void) {
+ int r = 0;
+
+#if HAVE_SELINUX
+ usec_t before_timestamp, after_timestamp;
+ struct mallinfo before_mallinfo, after_mallinfo;
+
+ if (label_hnd)
+ return 0;
+
+ if (!mac_selinux_use())
+ return 0;
+
+ before_mallinfo = mallinfo();
+ before_timestamp = now(CLOCK_MONOTONIC);
+
+ label_hnd = selabel_open(SELABEL_CTX_FILE, NULL, 0);
+ if (!label_hnd) {
+ log_enforcing_errno(errno, "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) {
+
+#if HAVE_SELINUX
+ if (!label_hnd)
+ return;
+
+ selabel_close(label_hnd);
+ label_hnd = NULL;
+#endif
+}
+
+int mac_selinux_fix(const char *path, LabelFixFlags flags) {
+
+#if HAVE_SELINUX
+ char procfs_path[STRLEN("/proc/self/fd/") + DECIMAL_STR_MAX(int)];
+ _cleanup_freecon_ char* fcon = NULL;
+ _cleanup_close_ int fd = -1;
+ struct stat st;
+ int r;
+
+ assert(path);
+
+ /* 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;
+ }
+
+ if (fstat(fd, &st) < 0)
+ return -errno;
+
+ if (selabel_lookup_raw(label_hnd, &fcon, path, st.st_mode) < 0) {
+ r = -errno;
+
+ /* If there's no label to set, then exit without warning */
+ if (r == -ENOENT)
+ return 0;
+
+ goto fail;
+ }
+
+ xsprintf(procfs_path, "/proc/self/fd/%i", fd);
+ if (setfilecon_raw(procfs_path, fcon) < 0) {
+ _cleanup_freecon_ char *oldcon = NULL;
+
+ r = -errno;
+
+ /* If the FS doesn't support labels, then exit without warning */
+ if (r == -EOPNOTSUPP)
+ return 0;
+
+ /* It the FS is read-only and we were told to ignore failures caused by that, suppress error */
+ if (r == -EROFS && (flags & LABEL_IGNORE_EROFS))
+ return 0;
+
+ /* 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:
+ log_enforcing_errno(r, "Unable to fix SELinux security context of %s: %m", path);
+ if (security_getenforce() == 1)
+ return r;
+#endif
+
+ return 0;
+}
+
+int mac_selinux_apply(const char *path, const char *label) {
+
+#if HAVE_SELINUX
+ if (!mac_selinux_use())
+ return 0;
+
+ assert(path);
+ assert(label);
+
+ if (setfilecon(path, label) < 0) {
+ log_enforcing_errno(errno, "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;
+
+#if HAVE_SELINUX
+ _cleanup_freecon_ char *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_raw(mycon, fcon, sclass, label);
+ if (r < 0)
+ return -errno;
+#endif
+
+ return r;
+}
+
+int mac_selinux_get_our_label(char **label) {
+ int r = -EOPNOTSUPP;
+
+ assert(label);
+
+#if 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;
+
+#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;
+
+ 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");
+ r = security_compute_create_raw(mycon, fcon, sclass, label);
+ if (r < 0)
+ return -errno;
+#endif
+
+ return r;
+}
+
+char* mac_selinux_free(char *label) {
+
+#if HAVE_SELINUX
+ if (!label)
+ return NULL;
+
+ if (!mac_selinux_use())
+ return NULL;
+
+ freecon(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));
+
+ 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;
+
+ log_enforcing_errno(errno, "Failed to determine SELinux security context for %s: %m", abspath);
+ } else {
+ if (setfscreatecon_raw(filecon) >= 0)
+ return 0; /* Success! */
+
+ log_enforcing_errno(errno, "Failed to set SELinux security context %s for %s: %m", filecon, abspath);
+ }
+
+ if (security_getenforce() > 0)
+ return -errno;
+
+ return 0;
+}
+#endif
+
+int mac_selinux_create_file_prepare_at(int dirfd, const char *path, mode_t mode) {
+ int r = 0;
+
+#if HAVE_SELINUX
+ _cleanup_free_ char *abspath = NULL;
+
+ 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;
+ }
+
+ r = selinux_create_file_prepare_abspath(path, mode);
+#endif
+ return r;
+}
+
+int mac_selinux_create_file_prepare(const char *path, mode_t mode) {
+ int r = 0;
+
+#if HAVE_SELINUX
+ _cleanup_free_ char *abspath = NULL;
+
+ assert(path);
+
+ if (!label_hnd)
+ return 0;
+
+ r = path_make_absolute_cwd(path, &abspath);
+ if (r < 0)
+ return r;
+
+ r = selinux_create_file_prepare_abspath(abspath, mode);
+#endif
+ return r;
+}
+
+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
+ if (!mac_selinux_use())
+ return 0;
+
+ assert(label);
+
+ if (setsockcreatecon(label) < 0) {
+ log_enforcing_errno(errno, "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) {
+
+#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));
+
+ 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_errno(errno, "Failed to determine SELinux security context for %s: %m", path);
+ if (security_getenforce() > 0)
+ return -errno;
+
+ } else {
+ if (setfscreatecon_raw(fcon) < 0) {
+ log_enforcing_errno(errno, "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_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 2024-08-13 11:44:12 +0000