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samba-mirror/source3/smbd/sec_ctx.c
Andrew Tridgell 3e9bcd111d don't try to initgroups in non root mode
(This used to be commit 1a04ea2476)
2001-09-19 03:30:20 +00:00

471 lines
11 KiB
C

/*
Unix SMB/Netbios implementation.
Version 1.9.
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 int DEBUGLEVEL;
extern struct current_user current_user;
struct sec_ctx {
uid_t uid;
uid_t gid;
int ngroups;
gid_t *groups;
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);
current_user.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);
current_user.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.
****************************************************************************/
int get_current_groups(int *p_ngroups, gid_t **p_groups)
{
int i;
gid_t grp;
int ngroups = sys_getgroups(0,&grp);
gid_t *groups;
(*p_ngroups) = 0;
(*p_groups) = NULL;
if (ngroups <= 0)
return -1;
if((groups = (gid_t *)malloc(sizeof(gid_t)*ngroups)) == NULL) {
DEBUG(0,("setup_groups malloc fail !\n"));
return -1;
}
if ((ngroups = sys_getgroups(ngroups,groups)) == -1) {
SAFE_FREE(groups);
return -1;
}
(*p_ngroups) = ngroups;
(*p_groups) = groups;
DEBUG( 3, ( "get_current_groups: uid %u is in %u groups: ", (unsigned int)getuid() , ngroups ) );
for (i = 0; i < ngroups; i++ ) {
DEBUG( 3, ( "%s%d", (i ? ", " : ""), (int)groups[i] ) );
}
DEBUG( 3, ( "\n" ) );
return ngroups;
}
/****************************************************************************
Delete a SID token.
****************************************************************************/
void delete_nt_token(NT_USER_TOKEN **pptoken)
{
if (*pptoken) {
NT_USER_TOKEN *ptoken = *pptoken;
SAFE_FREE( ptoken->user_sids );
ZERO_STRUCTP(ptoken);
}
SAFE_FREE(*pptoken);
}
/****************************************************************************
Duplicate a SID token.
****************************************************************************/
NT_USER_TOKEN *dup_nt_token(NT_USER_TOKEN *ptoken)
{
NT_USER_TOKEN *token;
if (!ptoken)
return NULL;
if ((token = (NT_USER_TOKEN *)malloc( sizeof(NT_USER_TOKEN) ) ) == NULL)
return NULL;
ZERO_STRUCTP(token);
if ((token->user_sids = (DOM_SID *)memdup( ptoken->user_sids, sizeof(DOM_SID) * ptoken->num_sids )) == NULL) {
SAFE_FREE(token);
return NULL;
}
token->num_sids = ptoken->num_sids;
return token;
}
/****************************************************************************
Initialize the groups a user belongs to.
****************************************************************************/
BOOL initialise_groups(char *user, uid_t uid, gid_t gid)
{
struct sec_ctx *prev_ctx_p;
BOOL result = True;
if (non_root_mode()) {
return True;
}
become_root();
/* Call initgroups() to get user groups */
if (winbind_initgroups(user,gid) == -1) {
DEBUG(0,("Unable to initgroups. Error was %s\n", strerror(errno) ));
if (getuid() == 0) {
if (gid < 0 || gid > 32767 || uid < 0 || uid > 32767) {
DEBUG(0,("This is probably a problem with the account %s\n", user));
}
}
result = False;
goto done;
}
/* Store groups in previous user's security context. This will
always work as the become_root() call increments the stack
pointer. */
prev_ctx_p = &sec_ctx_stack[sec_ctx_stack_ndx - 1];
SAFE_FREE(prev_ctx_p->groups);
prev_ctx_p->ngroups = 0;
get_current_groups(&prev_ctx_p->ngroups, &prev_ctx_p->groups);
done:
unbecome_root();
return result;
}
/****************************************************************************
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->uid = geteuid();
ctx_p->gid = getegid();
DEBUG(3, ("push_sec_ctx(%u, %u) : sec_ctx_stack_ndx = %d\n",
(unsigned int)ctx_p->uid, (unsigned int)ctx_p->gid, sec_ctx_stack_ndx ));
ctx_p->token = dup_nt_token(sec_ctx_stack[sec_ctx_stack_ndx-1].token);
ctx_p->ngroups = sys_getgroups(0, NULL);
if (ctx_p->ngroups != 0) {
if (!(ctx_p->groups = malloc(ctx_p->ngroups * sizeof(gid_t)))) {
DEBUG(0, ("Out of memory in push_sec_ctx()\n"));
delete_nt_token(&ctx_p->token);
return False;
}
sys_getgroups(ctx_p->ngroups, ctx_p->groups);
} else {
ctx_p->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));
if (ngroups) {
int i;
DEBUG(3, ("%d user groups: \n", ngroups));
for (i = 0; i < ngroups; i++) {
DEBUGADD(3, ("%u ", (unsigned int)groups[i]));
}
DEBUG(3, ("\n"));
}
gain_root();
#ifdef HAVE_SETGROUPS
sys_setgroups(ngroups, groups);
#endif
ctx_p->ngroups = ngroups;
SAFE_FREE(ctx_p->groups);
if (token && (token == ctx_p->token))
smb_panic("DUPLICATE_TOKEN");
delete_nt_token(&ctx_p->token);
ctx_p->groups = memdup(groups, sizeof(gid_t) * ngroups);
ctx_p->token = dup_nt_token(token);
become_id(uid, gid);
ctx_p->uid = uid;
ctx_p->gid = gid;
/* Update current_user stuff */
current_user.uid = uid;
current_user.gid = gid;
current_user.ngroups = ngroups;
current_user.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->uid = (uid_t)-1;
ctx_p->gid = (gid_t)-1;
SAFE_FREE(ctx_p->groups);
ctx_p->ngroups = 0;
delete_nt_token(&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->ngroups, prev_ctx_p->groups);
#endif
become_id(prev_ctx_p->uid, prev_ctx_p->gid);
/* Update current_user stuff */
current_user.uid = prev_ctx_p->uid;
current_user.gid = prev_ctx_p->gid;
current_user.ngroups = prev_ctx_p->ngroups;
current_user.groups = prev_ctx_p->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].uid = (uid_t)-1;
sec_ctx_stack[i].gid = (gid_t)-1;
}
/* Initialise first level of stack. It is the current context */
ctx_p = &sec_ctx_stack[0];
ctx_p->uid = geteuid();
ctx_p->gid = getegid();
get_current_groups(&ctx_p->ngroups, &ctx_p->groups);
ctx_p->token = NULL; /* Maps to guest user. */
/* Initialise current_user global */
current_user.uid = ctx_p->uid;
current_user.gid = ctx_p->gid;
current_user.ngroups = ctx_p->ngroups;
current_user.groups = ctx_p->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;
}