build-sys: split internal basic/ library from shared/

basic/      can be used by everything
            cannot use anything outside of basic/

libsystemd/ can use basic/
            cannot use shared/

shared/     can use libsystemd/

1 files changed, 462 insertions, 0 deletions

diff --git a/src/basic/selinux-util.c b/src/basic/selinux-util.c
new file mode 100644
index 0000000000..7c58985cd2
--- /dev/null
+++ b/src/basic/selinux-util.c
@@ -0,0 +1,462 @@
+/*-*- 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
+        assert(path);
+        assert(label);
+
+        if (!mac_selinux_use())
+                return 0;
+
+        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() == 1)
+                        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(&mycon);
+        if (r < 0)
+                return -errno;
+
+        r = getfilecon(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(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(&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(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;
+}
+
+void mac_selinux_free(char *label) {
+
+#ifdef HAVE_SELINUX
+        if (!mac_selinux_use())
+                return;
+
+        freecon((security_context_t) label);
+#endif
+}
+
+int mac_selinux_create_file_prepare(const char *path, mode_t mode) {
+        int r = 0;
+
+#ifdef HAVE_SELINUX
+        _cleanup_security_context_free_ security_context_t filecon = NULL;
+
+        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;
+
+                newpath = path_make_absolute_cwd(path);
+                if (!newpath)
+                        return -ENOMEM;
+
+                r = selabel_lookup_raw(label_hnd, &filecon, newpath, mode);
+        }
+
+        /* No context specified by the policy? Proceed without setting it. */
+        if (r < 0 && errno == ENOENT)
+                return 0;
+
+        if (r < 0)
+                r = -errno;
+        else {
+                r = setfscreatecon(filecon);
+                if (r < 0) {
+                        log_enforcing("Failed to set SELinux security context %s for %s: %m", filecon, path);
+                        r = -errno;
+                }
+        }
+
+        if (r < 0 && security_getenforce() == 0)
+                r = 0;
+#endif
+
+        return r;
+}
+
+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;
+        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 < 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_enforcing("Failed to set SELinux 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);
+        return r;
+
+skipped:
+#endif
+        return bind(fd, addr, addrlen) < 0 ? -errno : 0;
+}