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samba-mirror/source3/smbd/sec_ctx.c
Volker Lendecke 430fa0eba0 r17348: Some C++ warnings
(This used to be commit ae6b9b34e5)
2007-10-10 11:38:27 -05:00

401 lines
9.7 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 2 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, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "includes.h"
extern struct current_user current_user;
struct sec_ctx {
UNIX_USER_TOKEN ut;
NT_USER_TOKEN *token;
};
/* A stack of security contexts. We include the current context as being
the first one, so there is room for another MAX_SEC_CTX_DEPTH more. */
static struct sec_ctx sec_ctx_stack[MAX_SEC_CTX_DEPTH + 1];
static int sec_ctx_stack_ndx;
/****************************************************************************
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))) {
static int done;
if (!done) {
DEBUG(1,("WARNING: using uid %d is a security risk\n",
(int)uid));
done = 1;
}
}
/* 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))) {
static int done;
if (!done) {
DEBUG(1,("WARNING: using gid %d is a security risk\n",
(int)gid));
done = 1;
}
}
/* 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, int *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!\n");
}
/* 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;
}
/****************************************************************************
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);
gain_root();
#ifdef HAVE_SETGROUPS
sys_setgroups(ngroups, groups);
#endif
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;
}
become_id(uid, gid);
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!\n");
}
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--;
gain_root();
prev_ctx_p = &sec_ctx_stack[sec_ctx_stack_ndx];
#ifdef HAVE_SETGROUPS
sys_setgroups(prev_ctx_p->ut.ngroups, prev_ctx_p->ut.groups);
#endif
become_id(prev_ctx_p->ut.uid, prev_ctx_p->ut.gid);
/* 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;
}