postgresql/contrib/sepgsql/label.c
Robert Haas 568d4138c6 Use an MVCC snapshot, rather than SnapshotNow, for catalog scans.
SnapshotNow scans have the undesirable property that, in the face of
concurrent updates, the scan can fail to see either the old or the new
versions of the row.  In many cases, we work around this by requiring
DDL operations to hold AccessExclusiveLock on the object being
modified; in some cases, the existing locking is inadequate and random
failures occur as a result.  This commit doesn't change anything
related to locking, but will hopefully pave the way to allowing lock
strength reductions in the future.

The major issue has held us back from making this change in the past
is that taking an MVCC snapshot is significantly more expensive than
using a static special snapshot such as SnapshotNow.  However, testing
of various worst-case scenarios reveals that this problem is not
severe except under fairly extreme workloads.  To mitigate those
problems, we avoid retaking the MVCC snapshot for each new scan;
instead, we take a new snapshot only when invalidation messages have
been processed.  The catcache machinery already requires that
invalidation messages be sent before releasing the related heavyweight
lock; else other backends might rely on locally-cached data rather
than scanning the catalog at all.  Thus, making snapshot reuse
dependent on the same guarantees shouldn't break anything that wasn't
already subtly broken.

Patch by me.  Review by Michael Paquier and Andres Freund.
2013-07-02 09:47:01 -04:00

955 lines
24 KiB
C

/* -------------------------------------------------------------------------
*
* contrib/sepgsql/label.c
*
* Routines to support SELinux labels (security context)
*
* Copyright (c) 2010-2013, PostgreSQL Global Development Group
*
* -------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/heapam.h"
#include "access/htup_details.h"
#include "access/genam.h"
#include "access/xact.h"
#include "catalog/catalog.h"
#include "catalog/dependency.h"
#include "catalog/indexing.h"
#include "catalog/pg_attribute.h"
#include "catalog/pg_class.h"
#include "catalog/pg_database.h"
#include "catalog/pg_namespace.h"
#include "catalog/pg_proc.h"
#include "commands/dbcommands.h"
#include "commands/seclabel.h"
#include "libpq/auth.h"
#include "libpq/libpq-be.h"
#include "miscadmin.h"
#include "utils/builtins.h"
#include "utils/fmgroids.h"
#include "utils/guc.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/rel.h"
#include "utils/tqual.h"
#include "sepgsql.h"
#include <selinux/label.h>
/*
* Saved hook entries (if stacked)
*/
static ClientAuthentication_hook_type next_client_auth_hook = NULL;
static needs_fmgr_hook_type next_needs_fmgr_hook = NULL;
static fmgr_hook_type next_fmgr_hook = NULL;
/*
* client_label_*
*
* security label of the database client. Initially the client security label
* is equal to client_label_peer, and can be changed by one or more calls to
* sepgsql_setcon(), and also be temporarily overridden during execution of a
* trusted-procedure.
*
* sepgsql_setcon() is a transaction-aware operation; a (sub-)transaction
* rollback should also rollback the current client security label. Therefore
* we use the list client_label_pending of pending_label to keep track of which
* labels were set during the (sub-)transactions.
*/
static char *client_label_peer = NULL; /* set by getpeercon(3) */
static List *client_label_pending = NIL; /* pending list being set by
* sepgsql_setcon() */
static char *client_label_committed = NULL; /* set by sepgsql_setcon(),
* and already committed */
static char *client_label_func = NULL; /* set by trusted procedure */
typedef struct
{
SubTransactionId subid;
char *label;
} pending_label;
/*
* sepgsql_get_client_label
*
* Returns the current security label of the client. All code should use this
* routine to get the current label, instead of referring to the client_label_*
* variables above.
*/
char *
sepgsql_get_client_label(void)
{
/* trusted procedure client label override */
if (client_label_func)
return client_label_func;
/* uncommitted sepgsql_setcon() value */
if (client_label_pending)
{
pending_label *plabel = llast(client_label_pending);
if (plabel->label)
return plabel->label;
}
else if (client_label_committed)
return client_label_committed; /* set by sepgsql_setcon() committed */
/* default label */
Assert(client_label_peer != NULL);
return client_label_peer;
}
/*
* sepgsql_set_client_label
*
* This routine tries to switch the current security label of the client, and
* checks related permissions. The supplied new label shall be added to the
* client_label_pending list, then saved at transaction-commit time to ensure
* transaction-awareness.
*/
static void
sepgsql_set_client_label(const char *new_label)
{
const char *tcontext;
MemoryContext oldcxt;
pending_label *plabel;
/* Reset to the initial client label, if NULL */
if (!new_label)
tcontext = client_label_peer;
else
{
if (security_check_context_raw((security_context_t) new_label) < 0)
ereport(ERROR,
(errcode(ERRCODE_INVALID_NAME),
errmsg("SELinux: invalid security label: \"%s\"",
new_label)));
tcontext = new_label;
}
/* Check process:{setcurrent} permission. */
sepgsql_avc_check_perms_label(sepgsql_get_client_label(),
SEPG_CLASS_PROCESS,
SEPG_PROCESS__SETCURRENT,
NULL,
true);
/* Check process:{dyntransition} permission. */
sepgsql_avc_check_perms_label(tcontext,
SEPG_CLASS_PROCESS,
SEPG_PROCESS__DYNTRANSITION,
NULL,
true);
/*
* Append the supplied new_label on the pending list until the current
* transaction is committed.
*/
oldcxt = MemoryContextSwitchTo(CurTransactionContext);
plabel = palloc0(sizeof(pending_label));
plabel->subid = GetCurrentSubTransactionId();
if (new_label)
plabel->label = pstrdup(new_label);
client_label_pending = lappend(client_label_pending, plabel);
MemoryContextSwitchTo(oldcxt);
}
/*
* sepgsql_xact_callback
*
* A callback routine of transaction commit/abort/prepare. Commmit or abort
* changes in the client_label_pending list.
*/
static void
sepgsql_xact_callback(XactEvent event, void *arg)
{
if (event == XACT_EVENT_COMMIT)
{
if (client_label_pending != NIL)
{
pending_label *plabel = llast(client_label_pending);
char *new_label;
if (plabel->label)
new_label = MemoryContextStrdup(TopMemoryContext,
plabel->label);
else
new_label = NULL;
if (client_label_committed)
pfree(client_label_committed);
client_label_committed = new_label;
/*
* XXX - Note that items of client_label_pending are allocated on
* CurTransactionContext, thus, all acquired memory region shall
* be released implicitly.
*/
client_label_pending = NIL;
}
}
else if (event == XACT_EVENT_ABORT)
client_label_pending = NIL;
}
/*
* sepgsql_subxact_callback
*
* A callback routine of sub-transaction start/abort/commit. Releases all
* security labels that are set within the sub-transaction that is aborted.
*/
static void
sepgsql_subxact_callback(SubXactEvent event, SubTransactionId mySubid,
SubTransactionId parentSubid, void *arg)
{
ListCell *cell;
ListCell *prev;
ListCell *next;
if (event == SUBXACT_EVENT_ABORT_SUB)
{
prev = NULL;
for (cell = list_head(client_label_pending); cell; cell = next)
{
pending_label *plabel = lfirst(cell);
next = lnext(cell);
if (plabel->subid == mySubid)
client_label_pending
= list_delete_cell(client_label_pending, cell, prev);
else
prev = cell;
}
}
}
/*
* sepgsql_client_auth
*
* Entrypoint of the client authentication hook.
* It switches the client label according to getpeercon(), and the current
* performing mode according to the GUC setting.
*/
static void
sepgsql_client_auth(Port *port, int status)
{
if (next_client_auth_hook)
(*next_client_auth_hook) (port, status);
/*
* In the case when authentication failed, the supplied socket shall be
* closed soon, so we don't need to do anything here.
*/
if (status != STATUS_OK)
return;
/*
* Getting security label of the peer process using API of libselinux.
*/
if (getpeercon_raw(port->sock, &client_label_peer) < 0)
ereport(FATAL,
(errcode(ERRCODE_INTERNAL_ERROR),
errmsg("SELinux: unable to get peer label: %m")));
/*
* Switch the current performing mode from INTERNAL to either DEFAULT or
* PERMISSIVE.
*/
if (sepgsql_get_permissive())
sepgsql_set_mode(SEPGSQL_MODE_PERMISSIVE);
else
sepgsql_set_mode(SEPGSQL_MODE_DEFAULT);
}
/*
* sepgsql_needs_fmgr_hook
*
* It informs the core whether the supplied function is trusted procedure,
* or not. If true, sepgsql_fmgr_hook shall be invoked at start, end, and
* abort time of function invocation.
*/
static bool
sepgsql_needs_fmgr_hook(Oid functionId)
{
ObjectAddress object;
if (next_needs_fmgr_hook &&
(*next_needs_fmgr_hook) (functionId))
return true;
/*
* SELinux needs the function to be called via security_definer wrapper,
* if this invocation will take a domain-transition. We call these
* functions as trusted-procedure, if the security policy has a rule that
* switches security label of the client on execution.
*/
if (sepgsql_avc_trusted_proc(functionId) != NULL)
return true;
/*
* Even if not a trusted-procedure, this function should not be inlined
* unless the client has db_procedure:{execute} permission. Please note
* that it shall be actually failed later because of same reason with
* ACL_EXECUTE.
*/
object.classId = ProcedureRelationId;
object.objectId = functionId;
object.objectSubId = 0;
if (!sepgsql_avc_check_perms(&object,
SEPG_CLASS_DB_PROCEDURE,
SEPG_DB_PROCEDURE__EXECUTE |
SEPG_DB_PROCEDURE__ENTRYPOINT,
SEPGSQL_AVC_NOAUDIT, false))
return true;
return false;
}
/*
* sepgsql_fmgr_hook
*
* It switches security label of the client on execution of trusted
* procedures.
*/
static void
sepgsql_fmgr_hook(FmgrHookEventType event,
FmgrInfo *flinfo, Datum *private)
{
struct
{
char *old_label;
char *new_label;
Datum next_private;
} *stack;
switch (event)
{
case FHET_START:
stack = (void *) DatumGetPointer(*private);
if (!stack)
{
MemoryContext oldcxt;
oldcxt = MemoryContextSwitchTo(flinfo->fn_mcxt);
stack = palloc(sizeof(*stack));
stack->old_label = NULL;
stack->new_label = sepgsql_avc_trusted_proc(flinfo->fn_oid);
stack->next_private = 0;
MemoryContextSwitchTo(oldcxt);
/*
* process:transition permission between old and new label,
* when user tries to switch security label of the client on
* execution of trusted procedure.
*
* Also, db_procedure:entrypoint permission should be checked
* whether this procedure can perform as an entrypoint of the
* trusted procedure, or not. Note that db_procedure:execute
* permission shall be checked individually.
*/
if (stack->new_label)
{
ObjectAddress object;
object.classId = ProcedureRelationId;
object.objectId = flinfo->fn_oid;
object.objectSubId = 0;
sepgsql_avc_check_perms(&object,
SEPG_CLASS_DB_PROCEDURE,
SEPG_DB_PROCEDURE__ENTRYPOINT,
getObjectDescription(&object),
true);
sepgsql_avc_check_perms_label(stack->new_label,
SEPG_CLASS_PROCESS,
SEPG_PROCESS__TRANSITION,
NULL, true);
}
*private = PointerGetDatum(stack);
}
Assert(!stack->old_label);
if (stack->new_label)
{
stack->old_label = client_label_func;
client_label_func = stack->new_label;
}
if (next_fmgr_hook)
(*next_fmgr_hook) (event, flinfo, &stack->next_private);
break;
case FHET_END:
case FHET_ABORT:
stack = (void *) DatumGetPointer(*private);
if (next_fmgr_hook)
(*next_fmgr_hook) (event, flinfo, &stack->next_private);
if (stack->new_label)
{
client_label_func = stack->old_label;
stack->old_label = NULL;
}
break;
default:
elog(ERROR, "unexpected event type: %d", (int) event);
break;
}
}
/*
* sepgsql_init_client_label
*
* Initializes the client security label and sets up related hooks for client
* label management.
*/
void
sepgsql_init_client_label(void)
{
/*
* Set up dummy client label.
*
* XXX - note that PostgreSQL launches background worker process like
* autovacuum without authentication steps. So, we initialize sepgsql_mode
* with SEPGSQL_MODE_INTERNAL, and client_label with the security context
* of server process. Later, it also launches background of user session.
* In this case, the process is always hooked on post-authentication, and
* we can initialize the sepgsql_mode and client_label correctly.
*/
if (getcon_raw(&client_label_peer) < 0)
ereport(ERROR,
(errcode(ERRCODE_INTERNAL_ERROR),
errmsg("SELinux: failed to get server security label: %m")));
/* Client authentication hook */
next_client_auth_hook = ClientAuthentication_hook;
ClientAuthentication_hook = sepgsql_client_auth;
/* Trusted procedure hooks */
next_needs_fmgr_hook = needs_fmgr_hook;
needs_fmgr_hook = sepgsql_needs_fmgr_hook;
next_fmgr_hook = fmgr_hook;
fmgr_hook = sepgsql_fmgr_hook;
/* Transaction/Sub-transaction callbacks */
RegisterXactCallback(sepgsql_xact_callback, NULL);
RegisterSubXactCallback(sepgsql_subxact_callback, NULL);
}
/*
* sepgsql_get_label
*
* It returns a security context of the specified database object.
* If unlabeled or incorrectly labeled, the system "unlabeled" label
* shall be returned.
*/
char *
sepgsql_get_label(Oid classId, Oid objectId, int32 subId)
{
ObjectAddress object;
char *label;
object.classId = classId;
object.objectId = objectId;
object.objectSubId = subId;
label = GetSecurityLabel(&object, SEPGSQL_LABEL_TAG);
if (!label || security_check_context_raw((security_context_t) label))
{
security_context_t unlabeled;
if (security_get_initial_context_raw("unlabeled", &unlabeled) < 0)
ereport(ERROR,
(errcode(ERRCODE_INTERNAL_ERROR),
errmsg("SELinux: failed to get initial security label: %m")));
PG_TRY();
{
label = pstrdup(unlabeled);
}
PG_CATCH();
{
freecon(unlabeled);
PG_RE_THROW();
}
PG_END_TRY();
freecon(unlabeled);
}
return label;
}
/*
* sepgsql_object_relabel
*
* An entrypoint of SECURITY LABEL statement
*/
void
sepgsql_object_relabel(const ObjectAddress *object, const char *seclabel)
{
/*
* validate format of the supplied security label, if it is security
* context of selinux.
*/
if (seclabel &&
security_check_context_raw((security_context_t) seclabel) < 0)
ereport(ERROR,
(errcode(ERRCODE_INVALID_NAME),
errmsg("SELinux: invalid security label: \"%s\"", seclabel)));
/*
* Do actual permission checks for each object classes
*/
switch (object->classId)
{
case DatabaseRelationId:
sepgsql_database_relabel(object->objectId, seclabel);
break;
case NamespaceRelationId:
sepgsql_schema_relabel(object->objectId, seclabel);
break;
case RelationRelationId:
if (object->objectSubId == 0)
sepgsql_relation_relabel(object->objectId,
seclabel);
else
sepgsql_attribute_relabel(object->objectId,
object->objectSubId,
seclabel);
break;
case ProcedureRelationId:
sepgsql_proc_relabel(object->objectId, seclabel);
break;
default:
elog(ERROR, "unsupported object type: %u", object->classId);
break;
}
}
/*
* TEXT sepgsql_getcon(VOID)
*
* It returns the security label of the client.
*/
PG_FUNCTION_INFO_V1(sepgsql_getcon);
Datum
sepgsql_getcon(PG_FUNCTION_ARGS)
{
char *client_label;
if (!sepgsql_is_enabled())
PG_RETURN_NULL();
client_label = sepgsql_get_client_label();
PG_RETURN_TEXT_P(cstring_to_text(client_label));
}
/*
* BOOL sepgsql_setcon(TEXT)
*
* It switches the security label of the client.
*/
PG_FUNCTION_INFO_V1(sepgsql_setcon);
Datum
sepgsql_setcon(PG_FUNCTION_ARGS)
{
const char *new_label;
if (PG_ARGISNULL(0))
new_label = NULL;
else
new_label = TextDatumGetCString(PG_GETARG_DATUM(0));
sepgsql_set_client_label(new_label);
PG_RETURN_BOOL(true);
}
/*
* TEXT sepgsql_mcstrans_in(TEXT)
*
* It translate the given qualified MLS/MCS range into raw format
* when mcstrans daemon is working.
*/
PG_FUNCTION_INFO_V1(sepgsql_mcstrans_in);
Datum
sepgsql_mcstrans_in(PG_FUNCTION_ARGS)
{
text *label = PG_GETARG_TEXT_P(0);
char *raw_label;
char *result;
if (!sepgsql_is_enabled())
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("sepgsql is not enabled")));
if (selinux_trans_to_raw_context(text_to_cstring(label),
&raw_label) < 0)
ereport(ERROR,
(errcode(ERRCODE_INTERNAL_ERROR),
errmsg("SELinux: could not translate security label: %m")));
PG_TRY();
{
result = pstrdup(raw_label);
}
PG_CATCH();
{
freecon(raw_label);
PG_RE_THROW();
}
PG_END_TRY();
freecon(raw_label);
PG_RETURN_TEXT_P(cstring_to_text(result));
}
/*
* TEXT sepgsql_mcstrans_out(TEXT)
*
* It translate the given raw MLS/MCS range into qualified format
* when mcstrans daemon is working.
*/
PG_FUNCTION_INFO_V1(sepgsql_mcstrans_out);
Datum
sepgsql_mcstrans_out(PG_FUNCTION_ARGS)
{
text *label = PG_GETARG_TEXT_P(0);
char *qual_label;
char *result;
if (!sepgsql_is_enabled())
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("sepgsql is not currently enabled")));
if (selinux_raw_to_trans_context(text_to_cstring(label),
&qual_label) < 0)
ereport(ERROR,
(errcode(ERRCODE_INTERNAL_ERROR),
errmsg("SELinux: could not translate security label: %m")));
PG_TRY();
{
result = pstrdup(qual_label);
}
PG_CATCH();
{
freecon(qual_label);
PG_RE_THROW();
}
PG_END_TRY();
freecon(qual_label);
PG_RETURN_TEXT_P(cstring_to_text(result));
}
/*
* quote_object_names
*
* It tries to quote the supplied identifiers
*/
static char *
quote_object_name(const char *src1, const char *src2,
const char *src3, const char *src4)
{
StringInfoData result;
const char *temp;
initStringInfo(&result);
if (src1)
{
temp = quote_identifier(src1);
appendStringInfo(&result, "%s", temp);
if (src1 != temp)
pfree((void *) temp);
}
if (src2)
{
temp = quote_identifier(src2);
appendStringInfo(&result, ".%s", temp);
if (src2 != temp)
pfree((void *) temp);
}
if (src3)
{
temp = quote_identifier(src3);
appendStringInfo(&result, ".%s", temp);
if (src3 != temp)
pfree((void *) temp);
}
if (src4)
{
temp = quote_identifier(src4);
appendStringInfo(&result, ".%s", temp);
if (src4 != temp)
pfree((void *) temp);
}
return result.data;
}
/*
* exec_object_restorecon
*
* This routine is a helper called by sepgsql_restorecon; it set up
* initial security labels of database objects within the supplied
* catalog OID.
*/
static void
exec_object_restorecon(struct selabel_handle * sehnd, Oid catalogId)
{
Relation rel;
SysScanDesc sscan;
HeapTuple tuple;
char *database_name = get_database_name(MyDatabaseId);
char *namespace_name;
Oid namespace_id;
char *relation_name;
/*
* Open the target catalog. We don't want to allow writable accesses by
* other session during initial labeling.
*/
rel = heap_open(catalogId, AccessShareLock);
sscan = systable_beginscan(rel, InvalidOid, false,
NULL, 0, NULL);
while (HeapTupleIsValid(tuple = systable_getnext(sscan)))
{
Form_pg_database datForm;
Form_pg_namespace nspForm;
Form_pg_class relForm;
Form_pg_attribute attForm;
Form_pg_proc proForm;
char *objname;
int objtype = 1234;
ObjectAddress object;
security_context_t context;
/*
* The way to determine object name depends on object classes. So, any
* branches set up `objtype', `objname' and `object' here.
*/
switch (catalogId)
{
case DatabaseRelationId:
datForm = (Form_pg_database) GETSTRUCT(tuple);
objtype = SELABEL_DB_DATABASE;
objname = quote_object_name(NameStr(datForm->datname),
NULL, NULL, NULL);
object.classId = DatabaseRelationId;
object.objectId = HeapTupleGetOid(tuple);
object.objectSubId = 0;
break;
case NamespaceRelationId:
nspForm = (Form_pg_namespace) GETSTRUCT(tuple);
objtype = SELABEL_DB_SCHEMA;
objname = quote_object_name(database_name,
NameStr(nspForm->nspname),
NULL, NULL);
object.classId = NamespaceRelationId;
object.objectId = HeapTupleGetOid(tuple);
object.objectSubId = 0;
break;
case RelationRelationId:
relForm = (Form_pg_class) GETSTRUCT(tuple);
if (relForm->relkind == RELKIND_RELATION)
objtype = SELABEL_DB_TABLE;
else if (relForm->relkind == RELKIND_SEQUENCE)
objtype = SELABEL_DB_SEQUENCE;
else if (relForm->relkind == RELKIND_VIEW)
objtype = SELABEL_DB_VIEW;
else
continue; /* no need to assign security label */
namespace_name = get_namespace_name(relForm->relnamespace);
objname = quote_object_name(database_name,
namespace_name,
NameStr(relForm->relname),
NULL);
pfree(namespace_name);
object.classId = RelationRelationId;
object.objectId = HeapTupleGetOid(tuple);
object.objectSubId = 0;
break;
case AttributeRelationId:
attForm = (Form_pg_attribute) GETSTRUCT(tuple);
if (get_rel_relkind(attForm->attrelid) != RELKIND_RELATION)
continue; /* no need to assign security label */
objtype = SELABEL_DB_COLUMN;
namespace_id = get_rel_namespace(attForm->attrelid);
namespace_name = get_namespace_name(namespace_id);
relation_name = get_rel_name(attForm->attrelid);
objname = quote_object_name(database_name,
namespace_name,
relation_name,
NameStr(attForm->attname));
pfree(namespace_name);
pfree(relation_name);
object.classId = RelationRelationId;
object.objectId = attForm->attrelid;
object.objectSubId = attForm->attnum;
break;
case ProcedureRelationId:
proForm = (Form_pg_proc) GETSTRUCT(tuple);
objtype = SELABEL_DB_PROCEDURE;
namespace_name = get_namespace_name(proForm->pronamespace);
objname = quote_object_name(database_name,
namespace_name,
NameStr(proForm->proname),
NULL);
pfree(namespace_name);
object.classId = ProcedureRelationId;
object.objectId = HeapTupleGetOid(tuple);
object.objectSubId = 0;
break;
default:
elog(ERROR, "unexpected catalog id: %u", catalogId);
objname = NULL; /* for compiler quiet */
break;
}
if (selabel_lookup_raw(sehnd, &context, objname, objtype) == 0)
{
PG_TRY();
{
/*
* Check SELinux permission to relabel the fetched object,
* then do the actual relabeling.
*/
sepgsql_object_relabel(&object, context);
SetSecurityLabel(&object, SEPGSQL_LABEL_TAG, context);
}
PG_CATCH();
{
freecon(context);
PG_RE_THROW();
}
PG_END_TRY();
freecon(context);
}
else if (errno == ENOENT)
ereport(WARNING,
(errmsg("SELinux: no initial label assigned for %s (type=%d), skipping",
objname, objtype)));
else
ereport(ERROR,
(errcode(ERRCODE_INTERNAL_ERROR),
errmsg("SELinux: could not determine initial security label for %s (type=%d): %m", objname, objtype)));
pfree(objname);
}
systable_endscan(sscan);
heap_close(rel, NoLock);
}
/*
* BOOL sepgsql_restorecon(TEXT specfile)
*
* This function tries to assign initial security labels on all the object
* within the current database, according to the system setting.
* It is typically invoked by sepgsql-install script just after initdb, to
* assign initial security labels.
*
* If @specfile is not NULL, it uses explicitly specified specfile, instead
* of the system default.
*/
PG_FUNCTION_INFO_V1(sepgsql_restorecon);
Datum
sepgsql_restorecon(PG_FUNCTION_ARGS)
{
struct selabel_handle *sehnd;
struct selinux_opt seopts;
/*
* SELinux has to be enabled on the running platform.
*/
if (!sepgsql_is_enabled())
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("sepgsql is not currently enabled")));
/*
* Check DAC permission. Only superuser can set up initial security
* labels, like root-user in filesystems
*/
if (!superuser())
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
errmsg("SELinux: must be superuser to restore initial contexts")));
/*
* Open selabel_lookup(3) stuff. It provides a set of mapping between an
* initial security label and object class/name due to the system setting.
*/
if (PG_ARGISNULL(0))
{
seopts.type = SELABEL_OPT_UNUSED;
seopts.value = NULL;
}
else
{
seopts.type = SELABEL_OPT_PATH;
seopts.value = TextDatumGetCString(PG_GETARG_DATUM(0));
}
sehnd = selabel_open(SELABEL_CTX_DB, &seopts, 1);
if (!sehnd)
ereport(ERROR,
(errcode(ERRCODE_INTERNAL_ERROR),
errmsg("SELinux: failed to initialize labeling handle: %m")));
PG_TRY();
{
exec_object_restorecon(sehnd, DatabaseRelationId);
exec_object_restorecon(sehnd, NamespaceRelationId);
exec_object_restorecon(sehnd, RelationRelationId);
exec_object_restorecon(sehnd, AttributeRelationId);
exec_object_restorecon(sehnd, ProcedureRelationId);
}
PG_CATCH();
{
selabel_close(sehnd);
PG_RE_THROW();
}
PG_END_TRY();
selabel_close(sehnd);
PG_RETURN_BOOL(true);
}