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-rw-r--r--source3/smbd/share_access.c291
1 files changed, 291 insertions, 0 deletions
diff --git a/source3/smbd/share_access.c b/source3/smbd/share_access.c
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+++ b/source3/smbd/share_access.c
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+/*
+ Unix SMB/CIFS implementation.
+ Check access based on valid users, read list and friends
+ Copyright (C) Volker Lendecke 2005
+
+ 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/smbd.h"
+#include "smbd/globals.h"
+#include "../libcli/security/security.h"
+#include "passdb/lookup_sid.h"
+#include "auth.h"
+#include "source3/lib/substitute.h"
+
+/*
+ * No prefix means direct username
+ * @name means netgroup first, then unix group
+ * &name means netgroup
+ * +name means unix group
+ * + and & may be combined
+ */
+
+static bool do_group_checks(const char **name, const char **pattern)
+{
+ if ((*name)[0] == '@') {
+ *pattern = "&+";
+ *name += 1;
+ return True;
+ }
+
+ if (((*name)[0] == '+') && ((*name)[1] == '&')) {
+ *pattern = "+&";
+ *name += 2;
+ return True;
+ }
+
+ if ((*name)[0] == '+') {
+ *pattern = "+";
+ *name += 1;
+ return True;
+ }
+
+ if (((*name)[0] == '&') && ((*name)[1] == '+')) {
+ *pattern = "&+";
+ *name += 2;
+ return True;
+ }
+
+ if ((*name)[0] == '&') {
+ *pattern = "&";
+ *name += 1;
+ return True;
+ }
+
+ return False;
+}
+
+static bool token_contains_name(TALLOC_CTX *mem_ctx,
+ const char *username,
+ const char *domain,
+ const char *sharename,
+ const struct security_token *token,
+ const char *name)
+{
+ const char *prefix;
+ struct dom_sid sid;
+ enum lsa_SidType type;
+
+ if (username != NULL) {
+ size_t domain_len = domain != NULL ? strlen(domain) : 0;
+
+ /* Check if username starts with domain name */
+ if (domain_len > 0) {
+ const char *sep = lp_winbind_separator();
+ int cmp = strncasecmp_m(username, domain, domain_len);
+ if (cmp == 0 && sep[0] == username[domain_len]) {
+ /* Move after the winbind separator */
+ domain_len += 1;
+ } else {
+ domain_len = 0;
+ }
+ }
+ name = talloc_sub_basic(mem_ctx,
+ username + domain_len,
+ domain,
+ name);
+ }
+ if (sharename != NULL) {
+ name = talloc_string_sub(mem_ctx, name, "%S", sharename);
+ }
+
+ if (name == NULL) {
+ /* This is too security sensitive, better panic than return a
+ * result that might be interpreted in a wrong way. */
+ smb_panic("substitutions failed");
+ }
+
+ if ( string_to_sid( &sid, name ) ) {
+ DEBUG(5,("token_contains_name: Checking for SID [%s] in token\n", name));
+ return nt_token_check_sid( &sid, token );
+ }
+
+ if (!do_group_checks(&name, &prefix)) {
+ if (!lookup_name_smbconf(mem_ctx, name, LOOKUP_NAME_ALL,
+ NULL, NULL, &sid, &type)) {
+ DEBUG(5, ("lookup_name %s failed\n", name));
+ return False;
+ }
+ if (type != SID_NAME_USER) {
+ DEBUG(5, ("%s is a %s, expected a user\n",
+ name, sid_type_lookup(type)));
+ return False;
+ }
+ return nt_token_check_sid(&sid, token);
+ }
+
+ for (/* initialized above */ ; *prefix != '\0'; prefix++) {
+ if (*prefix == '+') {
+ if (!lookup_name_smbconf(mem_ctx, name,
+ LOOKUP_NAME_ALL|LOOKUP_NAME_GROUP,
+ NULL, NULL, &sid, &type)) {
+ DEBUG(5, ("lookup_name %s failed\n", name));
+ return False;
+ }
+ if ((type != SID_NAME_DOM_GRP) &&
+ (type != SID_NAME_ALIAS) &&
+ (type != SID_NAME_WKN_GRP)) {
+ DEBUG(5, ("%s is a %s, expected a group\n",
+ name, sid_type_lookup(type)));
+ return False;
+ }
+ if (nt_token_check_sid(&sid, token)) {
+ return True;
+ }
+ continue;
+ }
+ if (*prefix == '&') {
+ if (username) {
+ if (user_in_netgroup(mem_ctx, username, name)) {
+ return True;
+ }
+ }
+ continue;
+ }
+ smb_panic("got invalid prefix from do_groups_check");
+ }
+ return False;
+}
+
+/*
+ * Check whether a user is contained in the list provided.
+ *
+ * Please note that the user name and share names passed in here mainly for
+ * the substitution routines that expand the parameter values, the decision
+ * whether a user is in the list is done after a lookup_name on the expanded
+ * parameter value, solely based on comparing the SIDs in token.
+ *
+ * The other use is the netgroup check when using @group or &group.
+ */
+
+bool token_contains_name_in_list(const char *username,
+ const char *domain,
+ const char *sharename,
+ const struct security_token *token,
+ const char **list)
+{
+ if (list == NULL) {
+ return False;
+ }
+ while (*list != NULL) {
+ TALLOC_CTX *frame = talloc_stackframe();
+ bool ret;
+
+ ret = token_contains_name(frame, username, domain, sharename,
+ token, *list);
+ TALLOC_FREE(frame);
+ if (ret) {
+ return true;
+ }
+ list += 1;
+ }
+ return False;
+}
+
+/*
+ * Check whether the user described by "token" has access to share snum.
+ *
+ * This looks at "invalid users" and "valid users".
+ *
+ * Please note that the user name and share names passed in here mainly for
+ * the substitution routines that expand the parameter values, the decision
+ * whether a user is in the list is done after a lookup_name on the expanded
+ * parameter value, solely based on comparing the SIDs in token.
+ *
+ * The other use is the netgroup check when using @group or &group.
+ */
+
+bool user_ok_token(const char *username, const char *domain,
+ const struct security_token *token, int snum)
+{
+ const struct loadparm_substitution *lp_sub =
+ loadparm_s3_global_substitution();
+
+ if (lp_invalid_users(snum) != NULL) {
+ if (token_contains_name_in_list(username, domain,
+ lp_servicename(talloc_tos(), lp_sub, snum),
+ token,
+ lp_invalid_users(snum))) {
+ DEBUG(10, ("User %s in 'invalid users'\n", username));
+ return False;
+ }
+ }
+
+ if (lp_valid_users(snum) != NULL) {
+ if (!token_contains_name_in_list(username, domain,
+ lp_servicename(talloc_tos(), lp_sub, snum),
+ token,
+ lp_valid_users(snum))) {
+ DEBUG(10, ("User %s not in 'valid users'\n",
+ username));
+ return False;
+ }
+ }
+
+ DEBUG(10, ("user_ok_token: share %s is ok for unix user %s\n",
+ lp_servicename(talloc_tos(), lp_sub, snum), username));
+
+ return True;
+}
+
+/*
+ * Check whether the user described by "token" is restricted to read-only
+ * access on share snum.
+ *
+ * This looks at "read list", "write list" and "read only".
+ *
+ * Please note that the user name and share names passed in here mainly for
+ * the substitution routines that expand the parameter values, the decision
+ * whether a user is in the list is done after a lookup_name on the expanded
+ * parameter value, solely based on comparing the SIDs in token.
+ *
+ * The other use is the netgroup check when using @group or &group.
+ */
+
+bool is_share_read_only_for_token(const char *username,
+ const char *domain,
+ const struct security_token *token,
+ connection_struct *conn)
+{
+ const struct loadparm_substitution *lp_sub =
+ loadparm_s3_global_substitution();
+ int snum = SNUM(conn);
+ bool result = conn->read_only;
+
+ if (lp_read_list(snum) != NULL) {
+ if (token_contains_name_in_list(username, domain,
+ lp_servicename(talloc_tos(), lp_sub, snum),
+ token,
+ lp_read_list(snum))) {
+ result = True;
+ }
+ }
+
+ if (lp_write_list(snum) != NULL) {
+ if (token_contains_name_in_list(username, domain,
+ lp_servicename(talloc_tos(), lp_sub, snum),
+ token,
+ lp_write_list(snum))) {
+ result = False;
+ }
+ }
+
+ DEBUG(10,("is_share_read_only_for_user: share %s is %s for unix user "
+ "%s\n", lp_servicename(talloc_tos(), lp_sub, snum),
+ result ? "read-only" : "read-write", username));
+
+ return result;
+}
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