/*
* Copyright 2004-2020 the Pacemaker project contributors
*
* The version control history for this file may have further details.
*
* This source code is licensed under the GNU Lesser General Public License
* version 2.1 or later (LGPLv2.1+) WITHOUT ANY WARRANTY.
*/
#include <crm_internal.h>
#include <stdio.h>
#include <sys/types.h>
#include <pwd.h>
#include <string.h>
#include <stdlib.h>
#include <stdarg.h>
#include <libxml/tree.h>
#include <crm/crm.h>
#include <crm/msg_xml.h>
#include <crm/common/xml.h>
#include <crm/common/xml_internal.h>
#include "crmcommon_private.h"
#define MAX_XPATH_LEN 4096
typedef struct xml_acl_s {
enum xml_private_flags mode;
char *xpath;
} xml_acl_t;
static void
free_acl(void *data)
{
if (data) {
xml_acl_t *acl = data;
free(acl->xpath);
free(acl);
}
}
void
pcmk__free_acls(GList *acls)
{
g_list_free_full(acls, free_acl);
}
static GList *
create_acl(xmlNode *xml, GList *acls, enum xml_private_flags mode)
{
xml_acl_t *acl = NULL;
const char *tag = crm_element_value(xml, XML_ACL_ATTR_TAG);
const char *ref = crm_element_value(xml, XML_ACL_ATTR_REF);
const char *xpath = crm_element_value(xml, XML_ACL_ATTR_XPATH);
const char *attr = crm_element_value(xml, XML_ACL_ATTR_ATTRIBUTE);
if (tag == NULL) {
// @COMPAT rolling upgrades <=1.1.11
tag = crm_element_value(xml, XML_ACL_ATTR_TAGv1);
}
if (ref == NULL) {
// @COMPAT rolling upgrades <=1.1.11
ref = crm_element_value(xml, XML_ACL_ATTR_REFv1);
}
if ((tag == NULL) && (ref == NULL) && (xpath == NULL)) {
// Schema should prevent this, but to be safe ...
crm_trace("Ignoring ACL <%s> element without selection criteria",
crm_element_name(xml));
return NULL;
}
acl = calloc(1, sizeof (xml_acl_t));
CRM_ASSERT(acl != NULL);
acl->mode = mode;
if (xpath) {
acl->xpath = strdup(xpath);
CRM_ASSERT(acl->xpath != NULL);
crm_trace("Unpacked ACL <%s> element using xpath: %s",
crm_element_name(xml), acl->xpath);
} else {
int offset = 0;
char buffer[MAX_XPATH_LEN];
if (tag) {
offset += snprintf(buffer + offset, MAX_XPATH_LEN - offset,
"//%s", tag);
} else {
offset += snprintf(buffer + offset, MAX_XPATH_LEN - offset,
"//*");
}
if (ref || attr) {
offset += snprintf(buffer + offset, MAX_XPATH_LEN - offset,
"[");
}
if (ref) {
offset += snprintf(buffer + offset, MAX_XPATH_LEN - offset,
"@id='%s'", ref);
}
// NOTE: schema currently does not allow this
if (ref && attr) {
offset += snprintf(buffer + offset, MAX_XPATH_LEN - offset,
" and ");
}
if (attr) {
offset += snprintf(buffer + offset, MAX_XPATH_LEN - offset,
"@%s", attr);
}
if (ref || attr) {
offset += snprintf(buffer + offset, MAX_XPATH_LEN - offset,
"]");
}
CRM_LOG_ASSERT(offset > 0);
acl->xpath = strdup(buffer);
CRM_ASSERT(acl->xpath != NULL);
crm_trace("Unpacked ACL <%s> element as xpath: %s",
crm_element_name(xml), acl->xpath);
}
return g_list_append(acls, acl);
}
/*!
* \internal
* \brief Unpack a user, group, or role subtree of the ACLs section
*
* \param[in] acl_top XML of entire ACLs section
* \param[in] acl_entry XML of ACL element being unpacked
* \param[in,out] acls List of ACLs unpacked so far
*
* \return New head of (possibly modified) acls
*/
static GList *
parse_acl_entry(xmlNode *acl_top, xmlNode *acl_entry, GList *acls)
{
xmlNode *child = NULL;
for (child = pcmk__xe_first_child(acl_entry); child;
child = pcmk__xe_next(child)) {
const char *tag = crm_element_name(child);
const char *kind = crm_element_value(child, XML_ACL_ATTR_KIND);
if (strcmp(XML_ACL_TAG_PERMISSION, tag) == 0){
CRM_ASSERT(kind != NULL);
crm_trace("Unpacking ACL <%s> element of kind '%s'", tag, kind);
tag = kind;
} else {
crm_trace("Unpacking ACL <%s> element", tag);
}
if (strcmp(XML_ACL_TAG_ROLE_REF, tag) == 0
|| strcmp(XML_ACL_TAG_ROLE_REFv1, tag) == 0) {
const char *ref_role = crm_element_value(child, XML_ATTR_ID);
if (ref_role) {
xmlNode *role = NULL;
for (role = pcmk__xe_first_child(acl_top); role;
role = pcmk__xe_next(role)) {
if (!strcmp(XML_ACL_TAG_ROLE, (const char *) role->name)) {
const char *role_id = crm_element_value(role,
XML_ATTR_ID);
if (role_id && strcmp(ref_role, role_id) == 0) {
crm_trace("Unpacking referenced role '%s' in ACL <%s> element",
role_id, crm_element_name(acl_entry));
acls = parse_acl_entry(acl_top, role, acls);
break;
}
}
}
}
} else if (strcmp(XML_ACL_TAG_READ, tag) == 0) {
acls = create_acl(child, acls, xpf_acl_read);
} else if (strcmp(XML_ACL_TAG_WRITE, tag) == 0) {
acls = create_acl(child, acls, xpf_acl_write);
} else if (strcmp(XML_ACL_TAG_DENY, tag) == 0) {
acls = create_acl(child, acls, xpf_acl_deny);
} else {
crm_warn("Ignoring unknown ACL %s '%s'",
(kind? "kind" : "element"), tag);
}
}
return acls;
}
/*
<acls>
<acl_target id="l33t-haxor"><role id="auto-l33t-haxor"/></acl_target>
<acl_role id="auto-l33t-haxor">
<acl_permission id="crook-nothing" kind="deny" xpath="/cib"/>
</acl_role>
<acl_target id="niceguy">
<role id="observer"/>
</acl_target>
<acl_role id="observer">
<acl_permission id="observer-read-1" kind="read" xpath="/cib"/>
<acl_permission id="observer-write-1" kind="write" xpath="//nvpair[@name='stonith-enabled']"/>
<acl_permission id="observer-write-2" kind="write" xpath="//nvpair[@name='target-role']"/>
</acl_role>
<acl_target id="badidea"><role id="auto-badidea"/></acl_target>
<acl_role id="auto-badidea">
<acl_permission id="badidea-resources" kind="read" xpath="//meta_attributes"/>
<acl_permission id="badidea-resources-2" kind="deny" reference="dummy-meta_attributes"/>
</acl_role>
</acls>
*/
static const char *
acl_to_text(enum xml_private_flags flags)
{
if (pcmk_is_set(flags, xpf_acl_deny)) {
return "deny";
} else if (pcmk_any_flags_set(flags, xpf_acl_write|xpf_acl_create)) {
return "read/write";
} else if (pcmk_is_set(flags, xpf_acl_read)) {
return "read";
}
return "none";
}
void
pcmk__apply_acl(xmlNode *xml)
{
GListPtr aIter = NULL;
xml_private_t *p = xml->doc->_private;
xmlXPathObjectPtr xpathObj = NULL;
if (!xml_acl_enabled(xml)) {
crm_trace("Skipping ACLs for user '%s' because not enabled for this XML",
p->user);
return;
}
for (aIter = p->acls; aIter != NULL; aIter = aIter->next) {
int max = 0, lpc = 0;
xml_acl_t *acl = aIter->data;
xpathObj = xpath_search(xml, acl->xpath);
max = numXpathResults(xpathObj);
for (lpc = 0; lpc < max; lpc++) {
xmlNode *match = getXpathResult(xpathObj, lpc);
char *path = xml_get_path(match);
p = match->_private;
crm_trace("Applying %s ACL to %s matched by %s",
acl_to_text(acl->mode), path, acl->xpath);
#ifdef SUSE_ACL_COMPAT
if (!pcmk_is_set(p->flags, acl->mode)
&& pcmk_any_flags_set(p->flags,
xpf_acl_read|xpf_acl_write|xpf_acl_deny)) {
pcmk__config_warn("Configuration element %s is matched by "
"multiple ACL rules, only the first applies "
"('%s' wins over '%s')",
path, acl_to_text(p->flags),
acl_to_text(acl->mode));
free(path);
continue;
}
#endif
pcmk__set_xml_flags(p, acl->mode);
free(path);
}
crm_trace("Applied %s ACL %s (%d match%s)",
acl_to_text(acl->mode), acl->xpath, max,
((max == 1)? "" : "es"));
freeXpathObject(xpathObj);
}
}
/*!
* \internal
* \brief Unpack ACLs for a given user
*
* \param[in] source XML with ACL definitions
* \param[in,out] target XML that ACLs will be applied to
* \param[in] user Username whose ACLs need to be unpacked
*/
void
pcmk__unpack_acl(xmlNode *source, xmlNode *target, const char *user)
{
#if ENABLE_ACL
xml_private_t *p = NULL;
if ((target == NULL) || (target->doc == NULL)
|| (target->doc->_private == NULL)) {
return;
}
p = target->doc->_private;
if (!pcmk_acl_required(user)) {
crm_trace("Not unpacking ACLs because not required for user '%s'",
user);
} else if (p->acls == NULL) {
xmlNode *acls = get_xpath_object("//" XML_CIB_TAG_ACLS,
source, LOG_NEVER);
free(p->user);
p->user = strdup(user);
if (acls) {
xmlNode *child = NULL;
for (child = pcmk__xe_first_child(acls); child;
child = pcmk__xe_next(child)) {
const char *tag = crm_element_name(child);
if (!strcmp(tag, XML_ACL_TAG_USER)
|| !strcmp(tag, XML_ACL_TAG_USERv1)) {
const char *id = crm_element_value(child, XML_ATTR_ID);
if (id && strcmp(id, user) == 0) {
crm_debug("Unpacking ACLs for user '%s'", id);
p->acls = parse_acl_entry(acls, child, p->acls);
}
}
}
}
}
#endif
}
static inline bool
test_acl_mode(enum xml_private_flags allowed, enum xml_private_flags requested)
{
if (pcmk_is_set(allowed, xpf_acl_deny)) {
return false;
} else if (pcmk_all_flags_set(allowed, requested)) {
return true;
} else if (pcmk_is_set(requested, xpf_acl_read)
&& pcmk_is_set(allowed, xpf_acl_write)) {
return true;
} else if (pcmk_is_set(requested, xpf_acl_create)
&& pcmk_any_flags_set(allowed, xpf_acl_write|xpf_created)) {
return true;
}
return false;
}
static bool
purge_xml_attributes(xmlNode *xml)
{
xmlNode *child = NULL;
xmlAttr *xIter = NULL;
bool readable_children = false;
xml_private_t *p = xml->_private;
if (test_acl_mode(p->flags, xpf_acl_read)) {
crm_trace("%s[@id=%s] is readable", crm_element_name(xml), ID(xml));
return true;
}
xIter = xml->properties;
while (xIter != NULL) {
xmlAttr *tmp = xIter;
const char *prop_name = (const char *)xIter->name;
xIter = xIter->next;
if (strcmp(prop_name, XML_ATTR_ID) == 0) {
continue;
}
xmlUnsetProp(xml, tmp->name);
}
child = pcmk__xml_first_child(xml);
while ( child != NULL ) {
xmlNode *tmp = child;
child = pcmk__xml_next(child);
readable_children |= purge_xml_attributes(tmp);
}
if (!readable_children) {
free_xml(xml); /* Nothing readable under here, purge completely */
}
return readable_children;
}
/*!
* \internal
* \brief Copy ACL-allowed portions of specified XML
*
* \param[in] user Username whose ACLs should be used
* \param[in] acl_source XML containing ACLs
* \param[in] xml XML to be copied
* \param[out] result Copy of XML portions readable via ACLs
*
* \return true if xml exists and ACLs are required for user, false otherwise
* \note If this returns true, caller should use \p result rather than \p xml
*/
bool
xml_acl_filtered_copy(const char *user, xmlNode *acl_source, xmlNode *xml,
xmlNode **result)
{
GListPtr aIter = NULL;
xmlNode *target = NULL;
xml_private_t *doc = NULL;
*result = NULL;
if ((xml == NULL) || !pcmk_acl_required(user)) {
crm_trace("Not filtering XML because ACLs not required for user '%s'",
user);
return false;
}
crm_trace("Filtering XML copy using user '%s' ACLs", user);
target = copy_xml(xml);
if (target == NULL) {
return true;
}
pcmk__unpack_acl(acl_source, target, user);
pcmk__set_xml_doc_flag(target, xpf_acl_enabled);
pcmk__apply_acl(target);
doc = target->doc->_private;
for(aIter = doc->acls; aIter != NULL && target; aIter = aIter->next) {
int max = 0;
xml_acl_t *acl = aIter->data;
if (acl->mode != xpf_acl_deny) {
/* Nothing to do */
} else if (acl->xpath) {
int lpc = 0;
xmlXPathObjectPtr xpathObj = xpath_search(target, acl->xpath);
max = numXpathResults(xpathObj);
for(lpc = 0; lpc < max; lpc++) {
xmlNode *match = getXpathResult(xpathObj, lpc);
if (!purge_xml_attributes(match) && (match == target)) {
crm_trace("ACLs deny user '%s' access to entire XML document",
user);
freeXpathObject(xpathObj);
return true;
}
}
crm_trace("ACLs deny user '%s' access to %s (%d %s)",
user, acl->xpath, max,
pcmk__plural_alt(max, "match", "matches"));
freeXpathObject(xpathObj);
}
}
if (!purge_xml_attributes(target)) {
crm_trace("ACLs deny user '%s' access to entire XML document", user);
return true;
}
if (doc->acls) {
g_list_free_full(doc->acls, free_acl);
doc->acls = NULL;
} else {
crm_trace("User '%s' without ACLs denied access to entire XML document",
user);
free_xml(target);
target = NULL;
}
if (target) {
*result = target;
}
return true;
}
/*!
* \internal
* \brief Check whether creation of an XML element is implicitly allowed
*
* Check whether XML is a "scaffolding" element whose creation is implicitly
* allowed regardless of ACLs (that is, it is not in the ACL section and has
* no attributes other than "id").
*
* \param[in] xml XML element to check
*
* \return true if XML element is implicitly allowed, false otherwise
*/
static bool
implicitly_allowed(xmlNode *xml)
{
char *path = NULL;
for (xmlAttr *prop = xml->properties; prop != NULL; prop = prop->next) {
if (strcmp((const char *) prop->name, XML_ATTR_ID) != 0) {
return false;
}
}
path = xml_get_path(xml);
if (strstr(path, "/" XML_CIB_TAG_ACLS "/") != NULL) {
free(path);
return false;
}
free(path);
return true;
}
#define display_id(xml) (ID(xml)? ID(xml) : "<unset>")
/*!
* \internal
* \brief Drop XML nodes created in violation of ACLs
*
* Given an XML element, free all of its descendent nodes created in violation
* of ACLs, with the exception of allowing "scaffolding" elements (i.e. those
* that aren't in the ACL section and don't have any attributes other than
* "id").
*
* \param[in,out] xml XML to check
* \param[in] check_top Whether to apply checks to argument itself
* (if true, xml might get freed)
*/
void
pcmk__apply_creation_acl(xmlNode *xml, bool check_top)
{
xml_private_t *p = xml->_private;
if (pcmk_is_set(p->flags, xpf_created)) {
if (implicitly_allowed(xml)) {
crm_trace("Creation of <%s> scaffolding with id=\"%s\""
" is implicitly allowed",
crm_element_name(xml), display_id(xml));
} else if (pcmk__check_acl(xml, NULL, xpf_acl_write)) {
crm_trace("ACLs allow creation of <%s> with id=\"%s\"",
crm_element_name(xml), display_id(xml));
} else if (check_top) {
crm_trace("ACLs disallow creation of <%s> with id=\"%s\"",
crm_element_name(xml), display_id(xml));
pcmk_free_xml_subtree(xml);
return;
} else {
crm_notice("ACLs would disallow creation of %s<%s> with id=\"%s\" ",
((xml == xmlDocGetRootElement(xml->doc))? "root element " : ""),
crm_element_name(xml), display_id(xml));
}
}
for (xmlNode *cIter = pcmk__xml_first_child(xml); cIter != NULL; ) {
xmlNode *child = cIter;
cIter = pcmk__xml_next(cIter); /* In case it is free'd */
pcmk__apply_creation_acl(child, true);
}
}
bool
xml_acl_denied(xmlNode *xml)
{
if (xml && xml->doc && xml->doc->_private){
xml_private_t *p = xml->doc->_private;
return pcmk_is_set(p->flags, xpf_acl_denied);
}
return false;
}
void
xml_acl_disable(xmlNode *xml)
{
if (xml_acl_enabled(xml)) {
xml_private_t *p = xml->doc->_private;
/* Catch anything that was created but shouldn't have been */
pcmk__apply_acl(xml);
pcmk__apply_creation_acl(xml, false);
pcmk__clear_xml_flags(p, xpf_acl_enabled);
}
}
bool
xml_acl_enabled(xmlNode *xml)
{
if (xml && xml->doc && xml->doc->_private){
xml_private_t *p = xml->doc->_private;
return pcmk_is_set(p->flags, xpf_acl_enabled);
}
return false;
}
bool
pcmk__check_acl(xmlNode *xml, const char *name, enum xml_private_flags mode)
{
CRM_ASSERT(xml);
CRM_ASSERT(xml->doc);
CRM_ASSERT(xml->doc->_private);
#if ENABLE_ACL
if (pcmk__tracking_xml_changes(xml, false) && xml_acl_enabled(xml)) {
int offset = 0;
xmlNode *parent = xml;
char buffer[MAX_XPATH_LEN];
xml_private_t *docp = xml->doc->_private;
offset = pcmk__element_xpath(NULL, xml, buffer, offset,
sizeof(buffer));
if (name) {
offset += snprintf(buffer + offset, MAX_XPATH_LEN - offset,
"[@%s]", name);
}
CRM_LOG_ASSERT(offset > 0);
if (docp->acls == NULL) {
crm_trace("User '%s' without ACLs denied %s access to %s",
docp->user, acl_to_text(mode), buffer);
pcmk__set_xml_doc_flag(xml, xpf_acl_denied);
return false;
}
/* Walk the tree upwards looking for xml_acl_* flags
* - Creating an attribute requires write permissions for the node
* - Creating a child requires write permissions for the parent
*/
if (name) {
xmlAttr *attr = xmlHasProp(xml, (pcmkXmlStr) name);
if (attr && mode == xpf_acl_create) {
mode = xpf_acl_write;
}
}
while (parent && parent->_private) {
xml_private_t *p = parent->_private;
if (test_acl_mode(p->flags, mode)) {
return true;
} else if (pcmk_is_set(p->flags, xpf_acl_deny)) {
crm_trace("%sACL denies user '%s' %s access to %s",
(parent != xml) ? "Parent " : "", docp->user,
acl_to_text(mode), buffer);
pcmk__set_xml_doc_flag(xml, xpf_acl_denied);
return false;
}
parent = parent->parent;
}
crm_trace("Default ACL denies user '%s' %s access to %s",
docp->user, acl_to_text(mode), buffer);
pcmk__set_xml_doc_flag(xml, xpf_acl_denied);
return false;
}
#endif
return true;
}
/*!
* \brief Check whether ACLs are required for a given user
*
* \param[in] User name to check
*
* \return true if the user requires ACLs, false otherwise
*/
bool
pcmk_acl_required(const char *user)
{
#if ENABLE_ACL
if (pcmk__str_empty(user)) {
crm_trace("ACLs not required because no user set");
return false;
} else if (!strcmp(user, CRM_DAEMON_USER) || !strcmp(user, "root")) {
crm_trace("ACLs not required for privileged user %s", user);
return false;
}
crm_trace("ACLs required for %s", user);
return true;
#else
crm_trace("ACLs not required because not supported by this build");
return false;
#endif
}
#if ENABLE_ACL
char *
pcmk__uid2username(uid_t uid)
{
struct passwd *pwent = getpwuid(uid);
if (pwent == NULL) {
crm_perror(LOG_INFO, "Cannot get user details for user ID %d", uid);
return NULL;
}
return strdup(pwent->pw_name);
}
/*!
* \internal
* \brief Set the ACL user field properly on an XML request
*
* Multiple user names are potentially involved in an XML request: the effective
* user of the current process; the user name known from an IPC client
* connection; and the user name obtained from the request itself, whether by
* the current standard XML attribute name or an older legacy attribute name.
* This function chooses the appropriate one that should be used for ACLs, sets
* it in the request (using the standard attribute name, and the legacy name if
* given), and returns it.
*
* \param[in,out] request XML request to update
* \param[in] field Alternate name for ACL user name XML attribute
* \param[in] peer_user User name as known from IPC connection
*
* \return ACL user name actually used
*/
const char *
pcmk__update_acl_user(xmlNode *request, const char *field,
const char *peer_user)
{
static const char *effective_user = NULL;
const char *requested_user = NULL;
const char *user = NULL;
if (effective_user == NULL) {
effective_user = pcmk__uid2username(geteuid());
if (effective_user == NULL) {
effective_user = strdup("#unprivileged");
CRM_CHECK(effective_user != NULL, return NULL);
crm_err("Unable to determine effective user, assuming unprivileged for ACLs");
}
}
requested_user = crm_element_value(request, XML_ACL_TAG_USER);
if (requested_user == NULL) {
/* @COMPAT rolling upgrades <=1.1.11
*
* field is checked for backward compatibility with older versions that
* did not use XML_ACL_TAG_USER.
*/
requested_user = crm_element_value(request, field);
}
if (!pcmk__is_privileged(effective_user)) {
/* We're not running as a privileged user, set or overwrite any existing
* value for $XML_ACL_TAG_USER
*/
user = effective_user;
} else if (peer_user == NULL && requested_user == NULL) {
/* No user known or requested, use 'effective_user' and make sure one is
* set for the request
*/
user = effective_user;
} else if (peer_user == NULL) {
/* No user known, trusting 'requested_user' */
user = requested_user;
} else if (!pcmk__is_privileged(peer_user)) {
/* The peer is not a privileged user, set or overwrite any existing
* value for $XML_ACL_TAG_USER
*/
user = peer_user;
} else if (requested_user == NULL) {
/* Even if we're privileged, make sure there is always a value set */
user = peer_user;
} else {
/* Legal delegation to 'requested_user' */
user = requested_user;
}
// This requires pointer comparison, not string comparison
if (user != crm_element_value(request, XML_ACL_TAG_USER)) {
crm_xml_add(request, XML_ACL_TAG_USER, user);
}
if (field != NULL && user != crm_element_value(request, field)) {
crm_xml_add(request, field, user);
}
return requested_user;
}
#endif