relicense to LGPLv2.1 (with exceptions)

[thirdparty/systemd.git] / src / shared / capability.c

/*-*- 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 <assert.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <stdio.h>
#include <sys/types.h>
#include <stdarg.h>
#include <ctype.h>
#include <sys/capability.h>
#include <sys/prctl.h>

#include "macro.h"
#include "capability.h"
#include "util.h"
#include "log.h"

int have_effective_cap(int value) {
        cap_t cap;
        cap_flag_value_t fv;
        int r;

        if (!(cap = cap_get_proc()))
                return -errno;

        if (cap_get_flag(cap, value, CAP_EFFECTIVE, &fv) < 0)
                r = -errno;
        else
                r = fv == CAP_SET;

        cap_free(cap);
        return r;
}

unsigned long cap_last_cap(void) {
        static __thread unsigned long saved;
        static __thread bool valid = false;
        unsigned long p;

        if (valid)
                return saved;

        p = (unsigned long) CAP_LAST_CAP;

        if (prctl(PR_CAPBSET_READ, p) < 0) {

                /* Hmm, look downwards, until we find one that
                 * works */
                for (p--; p > 0; p --)
                        if (prctl(PR_CAPBSET_READ, p) >= 0)
                                break;

        } else {

                /* Hmm, look upwards, until we find one that doesn't
                 * work */
                for (;; p++)
                        if (prctl(PR_CAPBSET_READ, p+1) < 0)
                                break;
        }

        saved = p;
        valid = true;

        return p;
}