lirc-utils.c

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/****************************************************************************
 * lirc-utils.c *************************************************************
 ****************************************************************************
 */

#include <grp.h>
#include <pwd.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <unistd.h>

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#include "lirc/lirc_log.h"
#include "lirc-utils.h"

static const logchannel_t logchannel = LOG_LIB;

const char* drop_sudo_root(int (*set_some_uid)(uid_t))
{
        struct passwd* pw;
        char* user;
        GETGROUPS_T groups[32];
        int group_cnt = sizeof(groups)/sizeof(gid_t);
        char groupnames[256] = {0};
        char buff[12];
        int r;
        int i;

        if (getuid() != 0)
                return "";
        user = getenv("SUDO_USER");
        if (user == NULL)
                return "root";
        pw = getpwnam(user);
        if (pw == NULL) {
                log_perror_err("Can't run getpwnam() for %s", user);
                return "";
        }
        r = getgrouplist(user, pw->pw_gid, groups, &group_cnt);
        if (r == -1) {
                log_perror_warn("Cannot get supplementary groups");
                return "";
        }
        r = setgroups(group_cnt, groups);
        if (r == -1) {
                log_perror_warn("Cannot set supplementary groups");
                return "";
        }
        r = setgid(pw->pw_gid);
        if (r == -1) {
                log_perror_warn("Cannot set GID");
                return "";
        }
        r = set_some_uid(pw->pw_uid);
        if (r == -1) {
                log_perror_warn("Cannot change UID to %d", pw->pw_uid);
                return "";
        }
        setenv("HOME", pw->pw_dir, 1);
        log_notice("Running as user %s", user);
        for (i = 0; i < group_cnt; i += 1) {
                snprintf(buff, 5, " %d", groups[i]);
                strcat(groupnames, buff);
        }
        log_debug("Groups: [%d]:%s", pw->pw_gid, groupnames);

        return pw->pw_name;
}


void drop_root_cli(int (*set_some_uid)(uid_t))
{
        const char* new_user;

        new_user = drop_sudo_root(set_some_uid);
        if (strcmp("root", new_user) == 0)
                puts("Warning: Running as root.");
        else if (strlen(new_user) == 0)
                puts("Warning: Cannot change uid.");
        else
                printf("Running as regular user %s\n", new_user);
}