radlock.c

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/*
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program 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 General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */
 
/**
 * $Id: a34f01ab7d1045baa8c09d7e8d9fb2809ecd1e5b $
 *
 * @file radlock.c
 * @brief Utility to examine semaphores used to provide exclusive running rights for a process
 *
 * @copyright 2021 Arran Cudbard-Bell (a.cudbardb@freeradius.org)
 */
RCSID("$Id: a34f01ab7d1045baa8c09d7e8d9fb2809ecd1e5b $")
 
#include <freeradius-devel/autoconf.h>
#include <freeradius-devel/util/perm.h>
#include <freeradius-devel/util/sem.h>
#include <freeradius-devel/util/value.h>
#include <freeradius-devel/util/syserror.h>
#include <freeradius-devel/util/strerror.h>
 
#include <ctype.h>
#include <stdarg.h>
#include <stdbool.h>
#include <sys/ipc.h>
#include <sys/sem.h>
 
#ifdef HAVE_GETOPT_H
#  include <getopt.h>
#endif
#include <assert.h>
 
DIAG_OFF(unused-macros)
#define INFO(fmt, ...)          fprintf(stdout, fmt "\n", ## __VA_ARGS__)
DIAG_ON(unused-macros)
 
typedef enum {
        RADLOCK_INVALID = 0,
        RADLOCK_LOCK,           //!< Acquire the semaphore if it's at 0.
        RADLOCK_TRYLOCK,        //!< Try and lock the semaphore and return if we can't.
        RADLOCK_UNLOCK,         //!< Unlock the semaphore.
        RADLOCK_REMOVE,         //!< Remove the semaphore.
        RADLOCK_INFO,           //!< Information about the semaphore.
        RADLOCK_PERM            //!< Modify permissions for a given semaphore.
} fr_radlock_action_t;
 
static fr_table_num_sorted_t const radlock_action_table[] = {
        { L("info"),            RADLOCK_INFO    },
        { L("lock"),            RADLOCK_LOCK    },
        { L("perm"),            RADLOCK_PERM    },
        { L("remove"),          RADLOCK_REMOVE  },
        { L("trylock"),         RADLOCK_TRYLOCK },
        { L("unlock"),          RADLOCK_UNLOCK  }
};
static size_t radlock_action_table_len = NUM_ELEMENTS(radlock_action_table);
 
static NEVER_RETURNS void usage(int ret)
{
        fprintf(stderr, "usage: radlock <file> [lock|trylock|unlock|remove|info|perm]\n");
        fprintf(stderr, "  -u <uid>         Desired user.\n");
        fprintf(stderr, "  -g <gid>         Desired group.\n");
        fprintf(stderr, "  -m <perm>        Octal permissions string.\n");
        fprintf(stderr, "  -h               This help text.\n");
        fprintf(stderr, "\n");
        fprintf(stderr, "Simple utility to query the locking state of a config file\n");
        fr_exit_now(ret);
}
 
#define EXIT_WITH_FAILURE exit(EXIT_FAILURE)
#define EXIT_WITH_SUCCESS exit(EXIT_SUCCESS)
 
/**
 *
 * @hidecallgraph
 */
int main(int argc, char *argv[])
{
        char                    c;
        fr_radlock_action_t     action;
        char const              *file;
        uid_t                   uid = geteuid();
        bool                    uid_set = false;
        gid_t                   gid = getegid();
        bool                    gid_set = false;
        long                    mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH;
        bool                    mode_set = false;
        int                     sem_id;
 
        TALLOC_CTX              *autofree;
 
        autofree = talloc_autofree_context();
 
#ifndef NDEBUG
        if (fr_fault_setup(autofree, getenv("PANIC_ACTION"), argv[0]) < 0) {
                fr_perror("radict");
                fr_exit(EXIT_FAILURE);
        }
#endif
 
        talloc_set_log_stderr();
 
        while ((c = getopt(argc, argv, "u:g:m:h")) != -1) switch (c) {
                case 'u':
                        if (fr_perm_uid_from_str(autofree, &uid, optarg) < 0) {
                                fr_perror("radlock");
                                EXIT_WITH_FAILURE;
                        }
                        uid_set = true;
                        break;
 
                case 'g':
                        if (fr_perm_uid_from_str(autofree, &gid, optarg) < 0) {
                                fr_perror("radlock");
                                EXIT_WITH_FAILURE;
                        }
                        gid_set = true;
                        break;
 
                case 'm':
                        mode = strtol(optarg, NULL, 0); /* 0 base plus 0 prefix = octal */
                        if (errno == EINVAL) {
                                fr_perror("radlock - Bad mode value");
                                EXIT_WITH_FAILURE;
                        }
                        mode_set = true;
                        break;
 
                case 'h':
                default:
                        usage(EXIT_SUCCESS);
        }
        argc -= optind;
        argv += optind;
 
        if (argc == 0) {
                fr_perror("radlock - Need file to operate on");
                usage(64);
        }
 
        if (argc == 1) {
                fr_perror("radlock - Need action, must be one of (lock|trylock|unlock|remove|info|perm)");
                usage(64);
        }
 
        file = argv[0];
        action = fr_table_value_by_str(radlock_action_table, argv[1], RADLOCK_INVALID);
        if (action == RADLOCK_INVALID) {
                fr_perror("radlock - Action must be one of (lock|trylock|unlock|remove|info|perm), got %s", argv[1]);
                usage(64);
        }
 
        if (action == RADLOCK_PERM) {
                fr_perror("radlock - At least one of -u, -g, -m must be specified");
                usage(64);
        }
 
        /*
         *      Mismatch between the binary and the libraries it depends on
         */
        if (fr_check_lib_magic(RADIUSD_MAGIC_NUMBER) < 0) {
                fr_perror("radlock");
                EXIT_WITH_FAILURE;
        }
 
        switch (action) {
        case RADLOCK_LOCK:
        case RADLOCK_TRYLOCK:
                sem_id = fr_sem_get(file, 0, uid, gid, false, false);
                if (sem_id < 0) {
                        fr_perror("radlock");
                        EXIT_WITH_FAILURE;
                }
                switch (fr_sem_wait(sem_id, file, false, action == RADLOCK_TRYLOCK)) {
                case 1: /* Already locked */
                {
                        pid_t pid;
 
                        fr_sem_pid(&pid, sem_id);
                        fr_perror("radlock - Can't lock \"%s\" already held by PID %u", file, pid);
                        EXIT_WITH_FAILURE;
                }
 
                case 0:
                        EXIT_WITH_SUCCESS;
 
                default:
                        break;
                }
                fr_perror("radlock");
                EXIT_WITH_FAILURE;
 
        case RADLOCK_UNLOCK:
                sem_id = fr_sem_get(file, 0, uid, gid, false, true);
                if (sem_id == -4) EXIT_WITH_SUCCESS;
                if (sem_id < 0) {
                        fr_perror("radlock");
                        EXIT_WITH_FAILURE;
                }
 
        again:
                switch (fr_sem_post(sem_id, file, false)) {
                case 1: /* already unlocked */
                        EXIT_WITH_SUCCESS;
 
                case 0:
                        goto again;
 
                default:
                        break;
                }
                fr_perror("radlock");
                EXIT_WITH_FAILURE;
 
        case RADLOCK_REMOVE:
                sem_id = fr_sem_get(file, 0, uid, gid, false, true);
                if (sem_id == -4) EXIT_WITH_SUCCESS;
 
                if (fr_sem_close(sem_id, file) < 0) {
                        fr_perror("radlock");
                        EXIT_WITH_FAILURE;
                }
                EXIT_WITH_SUCCESS;
 
        case RADLOCK_INFO:
        {
                struct semid_ds info;
                char            buff[10];
                unsigned int    perm = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH;
                bool            dead = false;
                pid_t           pid;
                int             ret;
                int             value;
                char const      *uid_str, *gid_str, *cuid_str, *cgid_str;
 
                sem_id = fr_sem_get(file, 0, uid, gid, false, true);
                if (sem_id == -4) EXIT_WITH_FAILURE;
                if (sem_id < 0) {
                        fr_perror("radlock");
                        EXIT_WITH_FAILURE;
                }
 
                if (semctl(sem_id, 0, IPC_STAT, &info) < 0) {
                        fr_perror("radlock - Failed getting lock info for \"%s\": %s", file, fr_syserror(errno));
                        EXIT_WITH_FAILURE;
                }
 
                if (fr_sem_pid(&pid, sem_id) < 0) {
                        fr_perror("radlock");
                        EXIT_WITH_FAILURE;
                }
 
                ret = kill(sem_id, 0);
                if ((ret < 0) && (errno == ESRCH)) dead = true;
 
                uid_str = fr_perm_uid_to_str(autofree, info.sem_perm.uid);
                if (!uid_str) uid_str = "";
 
                gid_str = fr_perm_gid_to_str(autofree, info.sem_perm.gid);
                if (!gid_str) gid_str = "";
 
                cuid_str = fr_perm_uid_to_str(autofree, info.sem_perm.cuid);
                if (!cuid_str) cuid_str = "";
 
                cgid_str = fr_perm_gid_to_str(autofree, info.sem_perm.cgid);
                if (!cgid_str) cgid_str = "";
 
                value = semctl(sem_id, 0, GETVAL);
 
                INFO("Locking information for \"%s\"", file);
                INFO("\tsemid         : %u", sem_id);
                INFO("\tPermissions   : %s", fr_perm_mode_to_str(buff, info.sem_perm.mode & perm));
                INFO("\tValue         : %u (%s)", value, value > 0 ? "locked" : "unlocked");
                INFO("Last Modified:");
                INFO("\tPID           : %u (%s)", pid, dead ? "dead" : "alive");
                INFO("\tUser          : %s (%u)", uid_str, info.sem_perm.uid);
                INFO("\tGroup         : %s (%u)", gid_str, info.sem_perm.gid);
                INFO("\tTime          : %s",
                     fr_asprintf(autofree, "%pV", fr_box_time(fr_time_from_sec(info.sem_otime))));
                INFO("Created:");
                INFO("\tUser          : %s (%u)", cuid_str, info.sem_perm.cuid);
                INFO("\tGroup         : %s (%u)", cgid_str, info.sem_perm.cgid);
                INFO("\tTime          : %s",
                     fr_asprintf(autofree, "%pV", fr_box_time(fr_time_from_sec(info.sem_ctime))));
        }
                EXIT_WITH_SUCCESS;
 
        case RADLOCK_PERM:
        {
                struct semid_ds info;
 
                sem_id = fr_sem_get(file, 0, uid, gid, false, false);   /* Will create if does not already exist */
                if (sem_id < 0) {
                        fr_perror("radlock");
                        EXIT_WITH_FAILURE;
                }
 
                if (semctl(sem_id, 0, IPC_STAT, &info) < 0) {
                        fr_perror("radlock - Failed getting lock info for \"%s\": %s",
                                  fr_syserror(errno), file);
                        EXIT_WITH_FAILURE;
                }
 
                if (uid_set) info.sem_perm.uid = uid;
                if (gid_set) info.sem_perm.gid = gid;
                if (mode_set) info.sem_perm.mode = mode;
 
                if (semctl(sem_id, 0, IPC_SET, &info) < 0) {
                        fr_perror("radlock - Failed setting lock permissions for \"%s\": %s",
                                  fr_syserror(errno), file);
                        EXIT_WITH_FAILURE;
                }
        }
                EXIT_WITH_SUCCESS;
 
        case RADLOCK_INVALID:
                usage(64);
        }
 
        return 0;
}