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