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samba-mirror/source3/smbd/sec_ctx.c
Stefan Metzmacher 3dde0cbb76 s3:smbd: move all globals and static variables in globals.[ch]
The goal is to move all this variables into a big context structure.

metze
2009-01-08 12:22:21 +01:00

463 lines
12 KiB
C

/*
Unix SMB/CIFS implementation.
uid/user handling
Copyright (C) Tim Potter 2000
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 3 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, see <http://www.gnu.org/licenses/>.
*/
#include "includes.h"
#include "smbd/globals.h"
extern struct current_user current_user;
/****************************************************************************
Are two UNIX tokens equal ?
****************************************************************************/
bool unix_token_equal(const UNIX_USER_TOKEN *t1, const UNIX_USER_TOKEN *t2)
{
if (t1->uid != t2->uid || t1->gid != t2->gid ||
t1->ngroups != t2->ngroups) {
return false;
}
if (memcmp(t1->groups, t2->groups,
t1->ngroups*sizeof(gid_t)) != 0) {
return false;
}
return true;
}
/****************************************************************************
Become the specified uid.
****************************************************************************/
static bool become_uid(uid_t uid)
{
/* Check for dodgy uid values */
if (uid == (uid_t)-1 ||
((sizeof(uid_t) == 2) && (uid == (uid_t)65535))) {
if (!become_uid_done) {
DEBUG(1,("WARNING: using uid %d is a security risk\n",
(int)uid));
become_uid_done = true;
}
}
/* Set effective user id */
set_effective_uid(uid);
DO_PROFILE_INC(uid_changes);
return True;
}
/****************************************************************************
Become the specified gid.
****************************************************************************/
static bool become_gid(gid_t gid)
{
/* Check for dodgy gid values */
if (gid == (gid_t)-1 || ((sizeof(gid_t) == 2) &&
(gid == (gid_t)65535))) {
if (!become_gid_done) {
DEBUG(1,("WARNING: using gid %d is a security risk\n",
(int)gid));
become_gid_done = true;
}
}
/* Set effective group id */
set_effective_gid(gid);
return True;
}
/****************************************************************************
Become the specified uid and gid.
****************************************************************************/
static bool become_id(uid_t uid, gid_t gid)
{
return become_gid(gid) && become_uid(uid);
}
/****************************************************************************
Drop back to root privileges in order to change to another user.
****************************************************************************/
static void gain_root(void)
{
if (non_root_mode()) {
return;
}
if (geteuid() != 0) {
set_effective_uid(0);
if (geteuid() != 0) {
DEBUG(0,
("Warning: You appear to have a trapdoor "
"uid system\n"));
}
}
if (getegid() != 0) {
set_effective_gid(0);
if (getegid() != 0) {
DEBUG(0,
("Warning: You appear to have a trapdoor "
"gid system\n"));
}
}
}
/****************************************************************************
Get the list of current groups.
****************************************************************************/
static int get_current_groups(gid_t gid, size_t *p_ngroups, gid_t **p_groups)
{
int i;
gid_t grp;
int ngroups;
gid_t *groups = NULL;
(*p_ngroups) = 0;
(*p_groups) = NULL;
/* this looks a little strange, but is needed to cope with
systems that put the current egid in the group list
returned from getgroups() (tridge) */
save_re_gid();
set_effective_gid(gid);
setgid(gid);
ngroups = sys_getgroups(0,&grp);
if (ngroups <= 0) {
goto fail;
}
if((groups = SMB_MALLOC_ARRAY(gid_t, ngroups+1)) == NULL) {
DEBUG(0,("setup_groups malloc fail !\n"));
goto fail;
}
if ((ngroups = sys_getgroups(ngroups,groups)) == -1) {
goto fail;
}
restore_re_gid();
(*p_ngroups) = ngroups;
(*p_groups) = groups;
DEBUG( 3, ( "get_current_groups: user is in %u groups: ", ngroups));
for (i = 0; i < ngroups; i++ ) {
DEBUG( 3, ( "%s%d", (i ? ", " : ""), (int)groups[i] ) );
}
DEBUG( 3, ( "\n" ) );
return ngroups;
fail:
SAFE_FREE(groups);
restore_re_gid();
return -1;
}
/****************************************************************************
Create a new security context on the stack. It is the same as the old
one. User changes are done using the set_sec_ctx() function.
****************************************************************************/
bool push_sec_ctx(void)
{
struct sec_ctx *ctx_p;
/* Check we don't overflow our stack */
if (sec_ctx_stack_ndx == MAX_SEC_CTX_DEPTH) {
DEBUG(0, ("Security context stack overflow!\n"));
smb_panic("Security context stack overflow!");
}
/* Store previous user context */
sec_ctx_stack_ndx++;
ctx_p = &sec_ctx_stack[sec_ctx_stack_ndx];
ctx_p->ut.uid = geteuid();
ctx_p->ut.gid = getegid();
DEBUG(3, ("push_sec_ctx(%u, %u) : sec_ctx_stack_ndx = %d\n",
(unsigned int)ctx_p->ut.uid, (unsigned int)ctx_p->ut.gid, sec_ctx_stack_ndx ));
ctx_p->token = dup_nt_token(NULL,
sec_ctx_stack[sec_ctx_stack_ndx-1].token);
ctx_p->ut.ngroups = sys_getgroups(0, NULL);
if (ctx_p->ut.ngroups != 0) {
if (!(ctx_p->ut.groups = SMB_MALLOC_ARRAY(gid_t, ctx_p->ut.ngroups))) {
DEBUG(0, ("Out of memory in push_sec_ctx()\n"));
TALLOC_FREE(ctx_p->token);
return False;
}
sys_getgroups(ctx_p->ut.ngroups, ctx_p->ut.groups);
} else {
ctx_p->ut.groups = NULL;
}
return True;
}
/****************************************************************************
Change UNIX security context. Calls panic if not successful so no return value.
****************************************************************************/
#ifndef HAVE_DARWIN_INITGROUPS
/* Normal credential switch path. */
static void set_unix_security_ctx(uid_t uid, gid_t gid, int ngroups, gid_t *groups)
{
/* Start context switch */
gain_root();
#ifdef HAVE_SETGROUPS
if (sys_setgroups(gid, ngroups, groups) != 0 && !non_root_mode()) {
smb_panic("sys_setgroups failed");
}
#endif
become_id(uid, gid);
/* end context switch */
}
#else /* HAVE_DARWIN_INITGROUPS */
/* The Darwin groups implementation is a little unusual. The list of
* groups in the kernel credential is not exhaustive, but more like
* a cache. The full group list is held in userspace and checked
* dynamically.
*
* This is an optional mechanism, and setgroups(2) opts out
* of it. That is, if you call setgroups, then the list of groups you
* set are the only groups that are ever checked. This is not what we
* want. We want to opt in to the dynamic resolution mechanism, so we
* need to specify the uid of the user whose group list (cache) we are
* setting.
*
* The Darwin rules are:
* 1. Thou shalt setegid, initgroups and seteuid IN THAT ORDER
* 2. Thou shalt not pass more that NGROUPS_MAX to initgroups
* 3. Thou shalt leave the first entry in the groups list well alone
*/
#include <sys/syscall.h>
static void set_unix_security_ctx(uid_t uid, gid_t gid, int ngroups, gid_t *groups)
{
int max = groups_max();
/* Start context switch */
gain_root();
become_gid(gid);
if (syscall(SYS_initgroups, (ngroups > max) ? max : ngroups,
groups, uid) == -1 && !non_root_mode()) {
DEBUG(0, ("WARNING: failed to set group list "
"(%d groups) for UID %ld: %s\n",
ngroups, uid, strerror(errno)));
smb_panic("sys_setgroups failed");
}
become_uid(uid);
/* end context switch */
}
#endif /* HAVE_DARWIN_INITGROUPS */
/****************************************************************************
Set the current security context to a given user.
****************************************************************************/
void set_sec_ctx(uid_t uid, gid_t gid, int ngroups, gid_t *groups, NT_USER_TOKEN *token)
{
struct sec_ctx *ctx_p = &sec_ctx_stack[sec_ctx_stack_ndx];
/* Set the security context */
DEBUG(3, ("setting sec ctx (%u, %u) - sec_ctx_stack_ndx = %d\n",
(unsigned int)uid, (unsigned int)gid, sec_ctx_stack_ndx));
debug_nt_user_token(DBGC_CLASS, 5, token);
debug_unix_user_token(DBGC_CLASS, 5, uid, gid, ngroups, groups);
/* Change uid, gid and supplementary group list. */
set_unix_security_ctx(uid, gid, ngroups, groups);
ctx_p->ut.ngroups = ngroups;
SAFE_FREE(ctx_p->ut.groups);
if (token && (token == ctx_p->token)) {
smb_panic("DUPLICATE_TOKEN");
}
TALLOC_FREE(ctx_p->token);
if (ngroups) {
ctx_p->ut.groups = (gid_t *)memdup(groups,
sizeof(gid_t) * ngroups);
if (!ctx_p->ut.groups) {
smb_panic("memdup failed");
}
} else {
ctx_p->ut.groups = NULL;
}
if (token) {
ctx_p->token = dup_nt_token(NULL, token);
if (!ctx_p->token) {
smb_panic("dup_nt_token failed");
}
} else {
ctx_p->token = NULL;
}
ctx_p->ut.uid = uid;
ctx_p->ut.gid = gid;
/* Update current_user stuff */
current_user.ut.uid = uid;
current_user.ut.gid = gid;
current_user.ut.ngroups = ngroups;
current_user.ut.groups = groups;
current_user.nt_user_token = ctx_p->token;
}
/****************************************************************************
Become root context.
****************************************************************************/
void set_root_sec_ctx(void)
{
/* May need to worry about supplementary groups at some stage */
set_sec_ctx(0, 0, 0, NULL, NULL);
}
/****************************************************************************
Pop a security context from the stack.
****************************************************************************/
bool pop_sec_ctx(void)
{
struct sec_ctx *ctx_p;
struct sec_ctx *prev_ctx_p;
/* Check for stack underflow */
if (sec_ctx_stack_ndx == 0) {
DEBUG(0, ("Security context stack underflow!\n"));
smb_panic("Security context stack underflow!");
}
ctx_p = &sec_ctx_stack[sec_ctx_stack_ndx];
/* Clear previous user info */
ctx_p->ut.uid = (uid_t)-1;
ctx_p->ut.gid = (gid_t)-1;
SAFE_FREE(ctx_p->ut.groups);
ctx_p->ut.ngroups = 0;
TALLOC_FREE(ctx_p->token);
/* Pop back previous user */
sec_ctx_stack_ndx--;
prev_ctx_p = &sec_ctx_stack[sec_ctx_stack_ndx];
/* Change uid, gid and supplementary group list. */
set_unix_security_ctx(prev_ctx_p->ut.uid,
prev_ctx_p->ut.gid,
prev_ctx_p->ut.ngroups,
prev_ctx_p->ut.groups);
/* Update current_user stuff */
current_user.ut.uid = prev_ctx_p->ut.uid;
current_user.ut.gid = prev_ctx_p->ut.gid;
current_user.ut.ngroups = prev_ctx_p->ut.ngroups;
current_user.ut.groups = prev_ctx_p->ut.groups;
current_user.nt_user_token = prev_ctx_p->token;
DEBUG(3, ("pop_sec_ctx (%u, %u) - sec_ctx_stack_ndx = %d\n",
(unsigned int)geteuid(), (unsigned int)getegid(), sec_ctx_stack_ndx));
return True;
}
/* Initialise the security context system */
void init_sec_ctx(void)
{
int i;
struct sec_ctx *ctx_p;
/* Initialise security context stack */
memset(sec_ctx_stack, 0, sizeof(struct sec_ctx) * MAX_SEC_CTX_DEPTH);
for (i = 0; i < MAX_SEC_CTX_DEPTH; i++) {
sec_ctx_stack[i].ut.uid = (uid_t)-1;
sec_ctx_stack[i].ut.gid = (gid_t)-1;
}
/* Initialise first level of stack. It is the current context */
ctx_p = &sec_ctx_stack[0];
ctx_p->ut.uid = geteuid();
ctx_p->ut.gid = getegid();
get_current_groups(ctx_p->ut.gid, &ctx_p->ut.ngroups, &ctx_p->ut.groups);
ctx_p->token = NULL; /* Maps to guest user. */
/* Initialise current_user global */
current_user.ut.uid = ctx_p->ut.uid;
current_user.ut.gid = ctx_p->ut.gid;
current_user.ut.ngroups = ctx_p->ut.ngroups;
current_user.ut.groups = ctx_p->ut.groups;
/* The conn and vuid are usually taken care of by other modules.
We initialise them here. */
current_user.conn = NULL;
current_user.vuid = UID_FIELD_INVALID;
current_user.nt_user_token = NULL;
}