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/* abuild-sudo.c - limited root privileges for users in "abuild" group
*
* Copyright (C) 2012 Natanael Copa <ncopa@alpinelinux.org>
* All rights reserved.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published
* by the Free Software Foundation. See http://www.gnu.org/ for details.
*/
#include <sys/types.h>
#include <err.h>
#include <grp.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#ifndef ABUILD_GROUP
#define ABUILD_GROUP "abuild"
#endif
static const char* valid_cmds[] = {
"/bin/adduser",
"/usr/sbin/adduser",
"/bin/addgroup",
"/usr/sbin/addgroup",
"/sbin/apk",
"/usr/bin/abuild-rmtemp",
NULL
};
const char *get_command_path(const char *cmd)
{
const char *p;
int i;
for (i = 0; valid_cmds[i] != NULL; i++) {
if (access(valid_cmds[i], F_OK) == -1)
continue;
p = strrchr(valid_cmds[i], '/') + 1;
if (strcmp(p, cmd) == 0)
return valid_cmds[i];
}
return NULL;
}
int is_in_group(gid_t group)
{
int ngroups_max = sysconf(_SC_NGROUPS_MAX) + 1;
gid_t *buf = malloc(ngroups_max * sizeof(gid_t));
int ngroups;
int i;
if (buf == NULL) {
perror("malloc");
return 0;
}
ngroups = getgroups(ngroups_max, buf);
for (i = 0; i < ngroups; i++) {
if (buf[i] == group)
break;
}
free(buf);
return i < ngroups;
}
int main(int argc, const char *argv[])
{
struct group *grent;
const char *cmd;
const char *path;
int i;
struct passwd *pw;
grent = getgrnam(ABUILD_GROUP);
if (grent == NULL)
errx(1, "%s: Group not found", ABUILD_GROUP);
char *name = NULL;
pw = getpwuid(getuid());
if (pw)
name = pw->pw_name;
if (!is_in_group(grent->gr_gid)) {
errx(1, "User %s is not a member of group %s\n",
name ? name : "(unknown)", ABUILD_GROUP);
}
if (name == NULL)
warnx("Could not find username for uid %d\n", getuid());
setenv("USER", name ?: "", 1);
cmd = strrchr(argv[0], '/');
if (cmd)
cmd++;
else
cmd = argv[0];
cmd = strchr(cmd, '-');
if (cmd == NULL)
errx(1, "Calling command has no '-'");
cmd++;
path = get_command_path(cmd);
if (path == NULL)
errx(1, "%s: Not a valid subcommand", cmd);
/* we dont allow --allow-untrusted option */
for (i = 1; i < argc; i++)
if (strcmp(argv[i], "--allow-untrusted") == 0)
errx(1, "%s: not allowed option", "--allow-untrusted");
argv[0] = path;
/* set our uid to root so bbsuid --install works */
setuid(0);
/* set our gid to root so apk commit hooks run with the same gid as for "sudo apk add ..." */
setgid(0);
execv(path, (char * const*)argv);
perror(path);
return 1;
}
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