Adding upstream version 255.4.upstream/255.4

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 762 insertions, 0 deletions

diff --git a/src/shared/selinux-util.c b/src/shared/selinux-util.c
new file mode 100644
index 0000000..2fef29c
--- /dev/null
+++ b/src/shared/selinux-util.c
@@ -0,0 +1,762 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <errno.h>
+#include <fcntl.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 "label.h"
+#include "log.h"
+#include "macro.h"
+#include "mallinfo-util.h"
+#include "path-util.h"
+#include "selinux-util.h"
+#include "stdio-util.h"
+#include "time-util.h"
+
+#if HAVE_SELINUX
+DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(context_t, context_free, NULL);
+#define _cleanup_context_free_ _cleanup_(context_freep)
+
+typedef enum Initialized {
+        UNINITIALIZED,
+        INITIALIZED,
+        LAZY_INITIALIZED,
+} Initialized;
+
+static int mac_selinux_reload(int seqno);
+
+static int cached_use = -1;
+static Initialized initialized = UNINITIALIZED;
+static int last_policyload = 0;
+static struct selabel_handle *label_hnd = NULL;
+static bool have_status_page = false;
+
+#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(_level, _e, PROJECT_FILE, __LINE__, __func__, __VA_ARGS__) \
+                        : -ERRNO_VALUE(_e);                             \
+                _enforcing ? _r : 0;                                    \
+        })
+
+static int mac_selinux_label_pre(int dir_fd, const char *path, mode_t mode) {
+        return mac_selinux_create_file_prepare_at(dir_fd, path, mode);
+}
+
+static int mac_selinux_label_post(int dir_fd, const char *path) {
+        mac_selinux_create_file_clear();
+        return 0;
+}
+#endif
+
+bool mac_selinux_use(void) {
+#if HAVE_SELINUX
+        if (_unlikely_(cached_use < 0)) {
+                cached_use = is_selinux_enabled() > 0;
+                log_trace("SELinux enabled state cached to: %s", enabled_disabled(cached_use));
+        }
+
+        return cached_use;
+#else
+        return false;
+#endif
+}
+
+bool mac_selinux_enforcing(void) {
+        int r = 0;
+#if HAVE_SELINUX
+
+        /* If the SELinux status page has been successfully opened, retrieve the enforcing
+         * status over it to avoid system calls in security_getenforce(). */
+
+        if (have_status_page)
+                r = selinux_status_getenforce();
+        else
+                r = security_getenforce();
+
+#endif
+        return r != 0;
+}
+
+void mac_selinux_retest(void) {
+#if HAVE_SELINUX
+        cached_use = -1;
+#endif
+}
+
+#if HAVE_SELINUX
+static int open_label_db(void) {
+        struct selabel_handle *hnd;
+        /* Avoid maybe-uninitialized false positives */
+        usec_t before_timestamp = USEC_INFINITY, after_timestamp = USEC_INFINITY;
+#  if HAVE_GENERIC_MALLINFO
+        generic_mallinfo before_mallinfo = {};
+#  endif
+
+        if (DEBUG_LOGGING) {
+#  if HAVE_GENERIC_MALLINFO
+                before_mallinfo = generic_mallinfo_get();
+#  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");
+
+        if (DEBUG_LOGGING) {
+                after_timestamp = now(CLOCK_MONOTONIC);
+#  if HAVE_GENERIC_MALLINFO
+                generic_mallinfo after_mallinfo = generic_mallinfo_get();
+                size_t l = LESS_BY((size_t) after_mallinfo.uordblks, (size_t) before_mallinfo.uordblks);
+                log_debug("Successfully loaded SELinux database in %s, size on heap is %zuK.",
+                          FORMAT_TIMESPAN(after_timestamp - before_timestamp, 0),
+                          DIV_ROUND_UP(l, 1024));
+#  else
+                log_debug("Successfully loaded SELinux database in %s.",
+                          FORMAT_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
+
+static int selinux_init(bool force) {
+#if HAVE_SELINUX
+        static const LabelOps label_ops = {
+                .pre = mac_selinux_label_pre,
+                .post = mac_selinux_label_post,
+        };
+        int r;
+
+        if (!mac_selinux_use())
+                return 0;
+
+        if (initialized == INITIALIZED)
+                return 1;
+
+        /* Internal call from this module? Unless we were explicitly configured to allow lazy initialization
+         * bail out immediately. Pretend all is good, we do not want callers to abort here, for example at
+         * early boot when the policy is being initialised. */
+        if (!force && initialized != LAZY_INITIALIZED)
+                return 1;
+
+        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;
+        }
+
+        r = label_ops_set(&label_ops);
+        if (r < 0)
+                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();
+
+        initialized = INITIALIZED;
+        return 1;
+#else
+        return 0;
+#endif
+}
+
+int mac_selinux_init(void) {
+        return selinux_init(/* force= */ true);
+}
+
+int mac_selinux_init_lazy(void) {
+#if HAVE_SELINUX
+        if (initialized == UNINITIALIZED)
+                initialized = LAZY_INITIALIZED; /* We'll be back later */
+#endif
+
+        return 0;
+}
+
+void mac_selinux_maybe_reload(void) {
+#if HAVE_SELINUX
+        int policyload;
+
+        if (!initialized)
+                return;
+
+        /* Do not use selinux_status_updated(3), cause since libselinux 3.2 selinux_check_access(3),
+         * called in core and user instances, does also use it under the hood.
+         * That can cause changes to be consumed by selinux_check_access(3) and not being visible here.
+         * Also do not use selinux callbacks, selinux_set_callback(3), cause they are only automatically
+         * invoked since libselinux 3.2 by selinux_status_updated(3).
+         * Relevant libselinux commit: https://github.com/SELinuxProject/selinux/commit/05bdc03130d741e53e1fb45a958d0a2c184be503
+         * Debian Bullseye is going to ship libselinux 3.1, so stay compatible for backports. */
+        policyload = selinux_status_policyload();
+        if (policyload < 0) {
+                log_debug_errno(errno, "Failed to get SELinux policyload from status page: %m");
+                return;
+        }
+
+        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;
+        }
+
+        selinux_status_close();
+        have_status_page = false;
+
+        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
+
+#if HAVE_SELINUX
+static int selinux_fix_fd(
+                int fd,
+                const char *label_path,
+                LabelFixFlags flags) {
+
+        _cleanup_freecon_ char* fcon = NULL;
+        struct stat st;
+        int r;
+
+        assert(fd >= 0);
+        assert(label_path);
+        assert(path_is_absolute(label_path));
+
+        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 (!label_hnd)
+                return 0;
+
+        if (selabel_lookup_raw(label_hnd, &fcon, label_path, st.st_mode) < 0) {
+                /* If there's no label to set, then exit without warning */
+                if (errno == ENOENT)
+                        return 0;
+
+                return log_enforcing_errno(errno, "Unable to lookup intended SELinux security context of %s: %m", label_path);
+        }
+
+        if (setfilecon_raw(FORMAT_PROC_FD_PATH(fd), fcon) < 0) {
+                _cleanup_freecon_ char *oldcon = NULL;
+
+                r = -errno;
+
+                /* If the FS doesn't support labels, then exit without warning */
+                if (ERRNO_IS_NOT_SUPPORTED(r))
+                        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(FORMAT_PROC_FD_PATH(fd), &oldcon) >= 0 && streq_ptr(fcon, oldcon))
+                        return 0;
+
+                return log_enforcing_errno(r, "Unable to fix SELinux security context of %s: %m", label_path);
+        }
+
+        return 0;
+}
+#endif
+
+int mac_selinux_fix_full(
+                int atfd,
+                const char *inode_path,
+                const char *label_path,
+                LabelFixFlags flags) {
+
+        assert(atfd >= 0 || atfd == AT_FDCWD);
+        assert(atfd >= 0 || inode_path);
+
+#if HAVE_SELINUX
+        _cleanup_close_ int opened_fd = -EBADF;
+        _cleanup_free_ char *p = NULL;
+        int inode_fd, r;
+
+        r = selinux_init(/* force= */ false);
+        if (r <= 0)
+                return r;
+
+        if (!label_hnd)
+                return 0;
+
+        if (inode_path) {
+                opened_fd = openat(atfd, inode_path, O_NOFOLLOW|O_CLOEXEC|O_PATH);
+                if (opened_fd < 0) {
+                        if ((flags & LABEL_IGNORE_ENOENT) && errno == ENOENT)
+                                return 0;
+
+                        return -errno;
+                }
+
+                inode_fd = opened_fd;
+        } else
+                inode_fd = atfd;
+
+        if (!label_path) {
+                if (path_is_absolute(inode_path))
+                        label_path = inode_path;
+                else {
+                        r = fd_get_path(inode_fd, &p);
+                        if (r < 0)
+                                return r;
+
+                        label_path = p;
+                }
+        }
+
+        return selinux_fix_fd(inode_fd, label_path, flags);
+#else
+        return 0;
+#endif
+}
+
+int mac_selinux_apply(const char *path, const char *label) {
+
+        assert(path);
+
+#if HAVE_SELINUX
+        int r;
+
+        r = selinux_init(/* force= */ false);
+        if (r <= 0)
+                return r;
+
+        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
+        int r;
+
+        r = selinux_init(/* force= */ false);
+        if (r <= 0)
+                return r;
+
+        assert(label);
+
+        if (setfilecon(FORMAT_PROC_FD_PATH(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);
+
+        r = selinux_init(/* force= */ false);
+        if (r < 0)
+                return r;
+        if (r == 0)
+                return -EOPNOTSUPP;
+
+        if (getcon_raw(&mycon) < 0)
+                return -errno;
+        if (!mycon)
+                return -EOPNOTSUPP;
+
+        if (getfilecon_raw(exe, &fcon) < 0)
+                return -errno;
+        if (!fcon)
+                return -EOPNOTSUPP;
+
+        sclass = string_to_security_class("process");
+        if (sclass == 0)
+                return -ENOSYS;
+
+        return RET_NERRNO(security_compute_create_raw(mycon, fcon, sclass, label));
+#else
+        return -EOPNOTSUPP;
+#endif
+}
+
+int mac_selinux_get_our_label(char **ret) {
+        assert(ret);
+
+#if HAVE_SELINUX
+        int r;
+
+        r = selinux_init(/* force= */ false);
+        if (r < 0)
+                return r;
+        if (r == 0)
+                return -EOPNOTSUPP;
+
+        _cleanup_freecon_ char *con = NULL;
+        if (getcon_raw(&con) < 0)
+                return -errno;
+        if (!con)
+                return -EOPNOTSUPP;
+
+        *ret = TAKE_PTR(con);
+        return 0;
+#else
+        return -EOPNOTSUPP;
+#endif
+}
+
+int mac_selinux_get_child_mls_label(int socket_fd, const char *exe, const char *exec_label, char **ret_label) {
+#if HAVE_SELINUX
+        _cleanup_freecon_ char *mycon = NULL, *peercon = NULL, *fcon = NULL;
+        _cleanup_context_free_ context_t pcon = NULL, bcon = NULL;
+        const char *range = NULL, *bcon_str = NULL;
+        security_class_t sclass;
+        int r;
+
+        assert(socket_fd >= 0);
+        assert(exe);
+        assert(ret_label);
+
+        r = selinux_init(/* force= */ false);
+        if (r < 0)
+                return r;
+        if (r == 0)
+                return -EOPNOTSUPP;
+
+        if (getcon_raw(&mycon) < 0)
+                return -errno;
+        if (!mycon)
+                return -EOPNOTSUPP;
+
+        if (getpeercon_raw(socket_fd, &peercon) < 0)
+                return -errno;
+        if (!peercon)
+                return -EOPNOTSUPP;
+
+        if (!exec_label) { /* If there is no context set for next exec let's use context of target executable */
+                if (getfilecon_raw(exe, &fcon) < 0)
+                        return -errno;
+                if (!fcon)
+                        return -EOPNOTSUPP;
+        }
+
+        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;
+
+        if (context_range_set(bcon, range) != 0)
+                return -errno;
+
+        bcon_str = context_str(bcon);
+        if (!bcon_str)
+                return -ENOMEM;
+
+        sclass = string_to_security_class("process");
+        if (sclass == 0)
+                return -ENOSYS;
+
+        return RET_NERRNO(security_compute_create_raw(bcon_str, fcon, sclass, ret_label));
+#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));
+
+        r = selinux_init(/* force= */ false);
+        if (r <= 0)
+                return r;
+
+        /* Check for policy reload so 'label_hnd' is kept up-to-date by callbacks */
+        mac_selinux_maybe_reload();
+        if (!label_hnd)
+                return 0;
+
+        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 dir_fd,
+                const char *path,
+                mode_t mode) {
+
+#if HAVE_SELINUX
+        _cleanup_free_ char *abspath = NULL;
+        int r;
+
+        assert(dir_fd >= 0 || dir_fd == AT_FDCWD);
+
+        r = selinux_init(/* force= */ false);
+        if (r <= 0)
+                return r;
+
+        if (!label_hnd)
+                return 0;
+
+        if (isempty(path) || !path_is_absolute(path)) {
+                if (dir_fd == AT_FDCWD)
+                        r = safe_getcwd(&abspath);
+                else
+                        r = fd_get_path(dir_fd, &abspath);
+                if (r < 0)
+                        return r;
+
+                if (!isempty(path) && !path_extend(&abspath, path))
+                        return -ENOMEM;
+
+                path = abspath;
+        }
+
+        return selinux_create_file_prepare_abspath(path, mode);
+#else
+        return 0;
+#endif
+}
+
+int mac_selinux_create_file_prepare_label(const char *path, const char *label) {
+#if HAVE_SELINUX
+        int r;
+
+        if (!label)
+                return 0;
+
+        r = selinux_init(/* force= */ false);
+        if (r <= 0)
+                return r;
+
+        if (setfscreatecon_raw(label) < 0)
+                return log_enforcing_errno(errno, "Failed to set specified SELinux security context '%s' for '%s': %m", label, strna(path));
+#endif
+        return 0;
+}
+
+void mac_selinux_create_file_clear(void) {
+
+#if HAVE_SELINUX
+        PROTECT_ERRNO;
+
+        if (selinux_init(/* force= */ false) <= 0)
+                return;
+
+        setfscreatecon_raw(NULL);
+#endif
+}
+
+int mac_selinux_create_socket_prepare(const char *label) {
+
+#if HAVE_SELINUX
+        int r;
+
+        assert(label);
+
+        r = selinux_init(/* force= */ false);
+        if (r <= 0)
+                return r;
+
+        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 (selinux_init(/* force= */ false) <= 0)
+                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;
+        size_t sz;
+        char *path;
+        int r;
+
+        assert(fd >= 0);
+        assert(addr);
+        assert(addrlen >= sizeof(sa_family_t));
+
+        if (selinux_init(/* force= */ false) <= 0)
+                goto skipped;
+
+        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;
+
+        sz = addrlen - offsetof(struct sockaddr_un, sun_path);
+        if (sz > PATH_MAX)
+                goto skipped;
+        path = strndupa_safe(un->sun_path, sz);
+
+        /* Check for policy reload so 'label_hnd' is kept up-to-date by callbacks */
+        mac_selinux_maybe_reload();
+        if (!label_hnd)
+                goto skipped;
+
+        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 = RET_NERRNO(bind(fd, addr, addrlen));
+
+        if (context_changed)
+                (void) setfscreatecon_raw(NULL);
+
+        return r;
+
+skipped:
+#endif
+        return RET_NERRNO(bind(fd, addr, addrlen));
+}