src/core/smack-setup.c

/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/

/***
  This file is part of systemd.

  Copyright (C) 2013 Intel Corporation
  Authors:
        Nathaniel Chen <nathaniel.chen@intel.com>

  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 <stdio.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/vfs.h>
#include <fcntl.h>
#include <sys/types.h>
#include <dirent.h>
#include <sys/mount.h>
#include <stdint.h>

#include "macro.h"
#include "smack-setup.h"
#include "util.h"
#include "fileio.h"
#include "log.h"
#include "label.h"

#define SMACK_CONFIG "/etc/smack/accesses.d/"
#define CIPSO_CONFIG "/etc/smack/cipso.d/"

#ifdef HAVE_SMACK

static int write_rules(const char* dstpath, const char* srcdir) {
        _cleanup_fclose_ FILE *dst = NULL;
        _cleanup_closedir_ DIR *dir = NULL;
        struct dirent *entry;
        char buf[NAME_MAX];
        int dfd = -1;
        int r = 0;

        dst = fopen(dstpath, "we");
        if (!dst)  {
                if (errno != ENOENT)
                        log_warning("Failed to open %s: %m", dstpath);
                return -errno; /* negative error */
        }

        /* write rules to dst from every file in the directory */
        dir = opendir(srcdir);
        if (!dir) {
                if (errno != ENOENT)
                        log_warning("Failed to opendir %s: %m", srcdir);
                return errno; /* positive on purpose */
        }

        dfd = dirfd(dir);
        assert(dfd >= 0);

        FOREACH_DIRENT(entry, dir, return 0) {
                int fd;
                _cleanup_fclose_ FILE *policy = NULL;

                fd = openat(dfd, entry->d_name, O_RDONLY|O_CLOEXEC);
                if (fd < 0) {
                        if (r == 0)
                                r = -errno;
                        log_warning("Failed to open %s: %m", entry->d_name);
                        continue;
                }

                policy = fdopen(fd, "re");
                if (!policy) {
                        if (r == 0)
                                r = -errno;
                        safe_close(fd);
                        log_error("Failed to open %s: %m", entry->d_name);
                        continue;
                }

                /* load2 write rules in the kernel require a line buffered stream */
                FOREACH_LINE(buf, policy,
                             log_error("Failed to read line from %s: %m",
                                       entry->d_name)) {
                        if (!fputs(buf, dst)) {
                                if (r == 0)
                                        r = -EINVAL;
                                log_error("Failed to write line to %s", dstpath);
                                break;
                        }
                        if (fflush(dst)) {
                                if (r == 0)
                                        r = -errno;
                                log_error("Failed to flush writes to %s: %m", dstpath);
                                break;
                        }
                }
        }

       return r;
}

#endif

int mac_smack_setup(bool *loaded_policy) {

#ifdef HAVE_SMACK

        int r;

        assert(loaded_policy);

        r = write_rules("/sys/fs/smackfs/load2", SMACK_CONFIG);
        switch(r) {
        case -ENOENT:
                log_debug("Smack is not enabled in the kernel.");
                return 0;
        case ENOENT:
                log_debug("Smack access rules directory " SMACK_CONFIG " not found");
                return 0;
        case 0:
                log_info("Successfully loaded Smack policies.");
                break;
        default:
                log_warning("Failed to load Smack access rules: %s, ignoring.",
                            strerror(abs(r)));
                return 0;
        }

#ifdef SMACK_RUN_LABEL
        r = write_string_file("/proc/self/attr/current", SMACK_RUN_LABEL);
        if (r)
                log_warning("Failed to set SMACK label \"%s\" on self: %s",
                            SMACK_RUN_LABEL, strerror(-r));
#endif

        r = write_rules("/sys/fs/smackfs/cipso2", CIPSO_CONFIG);
        switch(r) {
        case -ENOENT:
                log_debug("Smack/CIPSO is not enabled in the kernel.");
                return 0;
        case ENOENT:
                log_debug("Smack/CIPSO access rules directory " CIPSO_CONFIG " not found");
                return 0;
        case 0:
                log_info("Successfully loaded Smack/CIPSO policies.");
                break;
        default:
                log_warning("Failed to load Smack/CIPSO access rules: %s, ignoring.",
                            strerror(abs(r)));
                return 0;
        }

        *loaded_policy = true;

#endif

        return 0;
}