src: elevate current identity privilege when fetching secret

When fetching the value of a private secret, we need to use an elevated
identity otherwise the secret driver will deny access.

When using the modular daemons, the elevated identity needs to be active
before the secret driver connection is opened, and it will apply to all
APIs calls made on that conncetion.

When using the monolithic daemon, the identity at time of opening the
connection is ignored, and the elevated identity needs to be active
precisely at the time the virSecretGetValue API call is made.

After acquiring the secret value, the elevated identity should be
cleared.

This sounds complex, but is fairly straightfoward with the automatic
cleanup callbacks.

Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

src/libxl/libxl_conf.c

@@ -31,6 +31,7 @@
 #include "datatypes.h"
 #include "virconf.h"
 #include "virfile.h"
+#include "viridentity.h"
 #include "virstring.h"
 #include "viralloc.h"
 #include "viruuid.h"
@@ -1001,6 +1002,10 @@ libxlMakeNetworkDiskSrc(virStorageSource *src, char **srcstr)
     if (src->auth && src->protocol == VIR_STORAGE_NET_PROTOCOL_RBD) {
         g_autofree uint8_t *secret = NULL;
         size_t secretlen = 0;
+        VIR_IDENTITY_AUTORESTORE virIdentity *oldident = virIdentityElevateCurrent();
+
+        if (!oldident)
+            goto cleanup;
 
         username = src->auth->username;
         if (!(conn = virConnectOpen("xen:///system")))

src/qemu/qemu_domain.c

@@ -41,6 +41,7 @@
 #include "viralloc.h"
 #include "virlog.h"
 #include "virerror.h"
+#include "viridentity.h"
 #include "cpu/cpu.h"
 #include "viruuid.h"
 #include "virfile.h"
@@ -1116,9 +1117,13 @@ qemuDomainSecretPlainSetup(qemuDomainSecretInfo *secinfo,
                            const char *username,
                            virSecretLookupTypeDef *seclookupdef)
 {
+    VIR_IDENTITY_AUTORESTORE virIdentity *oldident = virIdentityElevateCurrent();
     g_autoptr(virConnect) conn = virGetConnectSecret();
     int ret = -1;
 
+    if (!oldident)
+        return -1;
+
     if (!conn)
         return -1;
 
@@ -1213,11 +1218,15 @@ qemuDomainSecretAESSetupFromSecret(qemuDomainObjPrivate *priv,
                                    const char *username,
                                    virSecretLookupTypeDef *seclookupdef)
 {
-    g_autoptr(virConnect) conn = virGetConnectSecret();
     qemuDomainSecretInfo *secinfo;
     g_autofree char *alias = qemuAliasForSecret(srcalias, secretuse);
     g_autofree uint8_t *secret = NULL;
     size_t secretlen = 0;
+    VIR_IDENTITY_AUTORESTORE virIdentity *oldident = virIdentityElevateCurrent();
+    g_autoptr(virConnect) conn = virGetConnectSecret();
+
+    if (!oldident)
+        return NULL;
 
     if (!conn)
         return NULL;

src/qemu/qemu_tpm.c

@@ -33,6 +33,7 @@
 #include "vircommand.h"
 #include "viralloc.h"
 #include "virkmod.h"
+#include "viridentity.h"
 #include "virlog.h"
 #include "virutil.h"
 #include "viruuid.h"
@@ -366,6 +367,10 @@ qemuTPMSetupEncryption(const unsigned char *secretuuid,
     virSecretLookupTypeDef seclookupdef = {
          .type = VIR_SECRET_LOOKUP_TYPE_UUID,
     };
+    VIR_IDENTITY_AUTORESTORE virIdentity *oldident = virIdentityElevateCurrent();
+
+    if (!oldident)
+        return -1;
 
     conn = virGetConnectSecret();
     if (!conn)

src/storage/storage_backend_iscsi.c

@@ -34,6 +34,7 @@
 #include "virerror.h"
 #include "virfile.h"
 #include "viriscsi.h"
+#include "viridentity.h"
 #include "virlog.h"
 #include "virobject.h"
 #include "virstring.h"
@@ -263,6 +264,7 @@ virStorageBackendISCSISetAuth(const char *portal,
     virStorageAuthDef *authdef = source->auth;
     int ret = -1;
     virConnectPtr conn = NULL;
+    VIR_IDENTITY_AUTORESTORE virIdentity *oldident = NULL;
 
     if (!authdef || authdef->authType == VIR_STORAGE_AUTH_TYPE_NONE)
         return 0;
@@ -275,6 +277,9 @@ virStorageBackendISCSISetAuth(const char *portal,
         return -1;
     }
 
+    if (!(oldident = virIdentityElevateCurrent()))
+        return -1;
+
     conn = virGetConnectSecret();
     if (!conn)
         return -1;

src/storage/storage_backend_iscsi_direct.c

@@ -29,6 +29,7 @@
 #include "storage_util.h"
 #include "viralloc.h"
 #include "virerror.h"
+#include "viridentity.h"
 #include "virlog.h"
 #include "virobject.h"
 #include "virstring.h"
@@ -94,6 +95,7 @@ virStorageBackendISCSIDirectSetAuth(struct iscsi_context *iscsi,
     virStorageAuthDef *authdef = source->auth;
     int ret = -1;
     virConnectPtr conn = NULL;
+    VIR_IDENTITY_AUTORESTORE virIdentity *oldident = NULL;
 
     if (!authdef || authdef->authType == VIR_STORAGE_AUTH_TYPE_NONE)
         return 0;
@@ -107,6 +109,9 @@ virStorageBackendISCSIDirectSetAuth(struct iscsi_context *iscsi,
         return ret;
     }
 
+    if (!(oldident = virIdentityElevateCurrent()))
+        return -1;
+
     if (!(conn = virGetConnectSecret()))
         return ret;
 

src/storage/storage_backend_rbd.c

@@ -27,6 +27,7 @@
 #include "storage_backend_rbd.h"
 #include "storage_conf.h"
 #include "viralloc.h"
+#include "viridentity.h"
 #include "virlog.h"
 #include "viruuid.h"
 #include "virstring.h"
@@ -196,6 +197,7 @@ virStorageBackendRBDOpenRADOSConn(virStorageBackendRBDState *ptr,
     g_autofree char *mon_buff = NULL;
 
     if (authdef) {
+        VIR_IDENTITY_AUTORESTORE virIdentity *oldident = NULL;
         g_autofree char *rados_key = NULL;
         int rc;
 
@@ -206,6 +208,9 @@ virStorageBackendRBDOpenRADOSConn(virStorageBackendRBDState *ptr,
             goto cleanup;
         }
 
+        if (!(oldident = virIdentityElevateCurrent()))
+            goto cleanup;
+
         conn = virGetConnectSecret();
         if (!conn)
             return -1;

src/storage/storage_util.c

@@ -68,6 +68,7 @@
 #include "storage_source_conf.h"
 #include "virlog.h"
 #include "virfile.h"
+#include "viridentity.h"
 #include "virjson.h"
 #include "virqemu.h"
 #include "virstring.h"
@@ -1265,6 +1266,7 @@ storageBackendCreateQemuImgSecretPath(virStoragePoolObj *pool,
     size_t secretlen = 0;
     virConnectPtr conn = NULL;
     VIR_AUTOCLOSE fd = -1;
+    VIR_IDENTITY_AUTORESTORE virIdentity *oldident = NULL;
 
     if (!enc) {
         virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
@@ -1279,6 +1281,9 @@ storageBackendCreateQemuImgSecretPath(virStoragePoolObj *pool,
         return NULL;
     }
 
+    if (!(oldident = virIdentityElevateCurrent()))
+        return NULL;
+
     conn = virGetConnectSecret();
     if (!conn)
         return NULL;

tests/qemuxml2argvmock.c

@@ -18,10 +18,13 @@
 
 #include <config.h>
 
+#define LIBVIRT_VIRIDENTITYPRIV_H_ALLOW
+
 #include "internal.h"
 #include "viralloc.h"
 #include "vircommand.h"
 #include "vircrypto.h"
+#include "viridentitypriv.h"
 #include "virmock.h"
 #include "virlog.h"
 #include "virnetdev.h"
@@ -292,3 +295,9 @@ qemuInterfaceVDPAConnect(virDomainNetDef *net G_GNUC_UNUSED)
         abort();
     return 1732;
 }
+
+char *
+virIdentityEnsureSystemToken(void)
+{
+    return g_strdup("3de80bcbf22d4833897f1638e01be9b2");
+}

tests/qemuxml2argvtest.c

@@ -11,6 +11,7 @@
 
 # include "internal.h"
 # include "viralloc.h"
+# include "viridentity.h"
 # include "qemu/qemu_alias.h"
 # include "qemu/qemu_capabilities.h"
 # include "qemu/qemu_command.h"
@@ -650,6 +651,7 @@ testCompareXMLToArgv(const void *data)
     xmlNodePtr root;
     g_autofree char *archstr = NULL;
     virArch arch = VIR_ARCH_NONE;
+    g_autoptr(virIdentity) sysident = virIdentityGetSystem();
 
     if (info->arch != VIR_ARCH_NONE && info->arch != VIR_ARCH_X86_64)
         qemuTestSetHostArch(&driver, info->arch);
@@ -670,6 +672,9 @@ testCompareXMLToArgv(const void *data)
     virSetConnectSecret(conn);
     virSetConnectStorage(conn);
 
+    if (virIdentitySetCurrent(sysident) < 0)
+        goto cleanup;
+
     if (testCheckExclusiveFlags(info->flags) < 0)
         goto cleanup;
 
@@ -809,6 +814,7 @@ testCompareXMLToArgv(const void *data)
     VIR_FREE(log);
     virDomainChrSourceDefClear(&monitor_chr);
     virObjectUnref(vm);
+    virIdentitySetCurrent(NULL);
     virSetConnectSecret(NULL);
     virSetConnectStorage(NULL);
     if (info->arch != VIR_ARCH_NONE && info->arch != VIR_ARCH_X86_64)