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/* This file is part of Smap.
Copyright (C) 2007, 2008, 2010 Sergey Poznyakoff
Smap 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 3, or (at your option)
any later version.
Smap 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 Smap. If not, see <http://www.gnu.org/licenses/>. */
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include "smapd.h"
void
privinfo_set_user(struct privinfo *pi, const char *name)
{
struct passwd *pw = getpwnam(name);
if (!pw) {
smap_error("%s: no such user", name);
return;
}
pi->uid = pw->pw_uid;
privinfo_add_grpgid(pi, pw->pw_gid);
}
void
privinfo_add_grpgid(struct privinfo *pi, gid_t gid)
{
if (pi->gc == 0) {
pi->gc = 16;
pi->gids = ecalloc(pi->gc, sizeof(pi->gids[0]));
pi->gi = 0;
}
if (pi->gi == pi->gc) {
pi->gc *= 2;
pi->gids = erealloc(pi->gids, pi->gc * sizeof(pi->gids[0]));
}
pi->gids[pi->gi++] = gid;
}
void
privinfo_add_grpnam(struct privinfo *pi, const char *name)
{
struct group *gr = getgrnam(name);
if (!gr) {
smap_error("%s: no such group", name);
return;
}
privinfo_add_grpgid(pi, gr->gr_gid);
}
void
get_user_groups(struct privinfo *pi)
{
struct group *gr;
struct passwd *pw;
const char *user;
pw = getpwuid(pi->uid);
if (!pw)
return;
user = pw->pw_name;
setgrent();
while (gr = getgrent()) {
char **p;
for (p = gr->gr_mem; *p; p++)
if (strcmp(*p, user) == 0) {
privinfo_add_grpgid(pi, gr->gr_gid);
break;
}
}
endgrent();
}
void
privinfo_expand_user_groups(struct privinfo *pi)
{
if (pi->allgroups) {
get_user_groups(pi);
pi->allgroups = 0;
}
}
/* Switch to the given UID/GID */
int
switch_to_privs(struct privinfo *pi)
{
int rc = 0;
uid_t uid = pi->uid;
gid_t gid;
if (uid == 0)
return 0;
/* Reset group permissions */
if (geteuid() == 0 && setgroups(pi->gi, pi->gids)) {
smap_error("setgroups failed: %s", strerror(errno));
return 1;
}
/* Switch to the user's gid. On some OSes the effective gid must
be reset first */
gid = pi->gids[0];
#if defined(HAVE_SETEGID)
if ((rc = setegid(gid)) < 0)
smap_error("setegid(%lu) failed: %s",
(unsigned long) gid, strerror(errno));
#elif defined(HAVE_SETREGID)
if ((rc = setregid(gid, gid)) < 0)
smap_error("setregid(%lu,%lu) failed: %s",
(unsigned long) gid, (unsigned long) gid,
strerror(errno));
#elif defined(HAVE_SETRESGID)
if ((rc = setresgid(gid, gid, gid)) < 0)
smap_error("setresgid(%lu,%lu,%lu) failed: %s",
(unsigned long) gid,
(unsigned long) gid,
(unsigned long) gid,
strerror(errno));
#endif
if (rc == 0 && gid != 0) {
if ((rc = setgid(gid)) < 0 && getegid() != gid)
smap_error("setgid(%lu) failed: %s",
(unsigned long) gid, strerror(errno));
if (rc == 0 && getegid() != gid) {
smap_error("cannot set effective gid to %lu",
(unsigned long) gid);
rc = 1;
}
}
/* Now reset uid */
if (rc == 0 && uid != 0) {
uid_t euid;
if (setuid(uid)
|| geteuid() != uid
|| (getuid() != uid
&& (geteuid() == 0 || getuid() == 0))) {
#if defined(HAVE_SETREUID)
if (geteuid() != uid) {
if (setreuid(uid, -1) < 0) {
smap_error("setreuid(%lu,-1) failed: %s",
(unsigned long) uid,
strerror(errno));
rc = 1;
}
if (setuid(uid) < 0) {
smap_error("second setuid(%lu) failed: %s",
(unsigned long) uid,
strerror(errno));
rc = 1;
}
} else
#endif
{
smap_error("setuid(%lu) failed: %s",
(unsigned long) uid,
strerror(errno));
rc = 1;
}
}
euid = geteuid();
if (uid != 0 && setuid(0) == 0) {
smap_error("seteuid(0) succeeded when it should not");
rc = 1;
} else if (uid != euid && setuid(euid) == 0) {
smap_error("cannot drop non-root setuid privileges");
rc = 1;
}
}
return rc;
}
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