Now that we have the functionality to provide the secrets driver
with an encryption key through a configuration file or using system
credentials, and the newly introduced array to iterate over the
encryption schemes, we can use the key to save and load secrets.

Encrypt all secrets that are going to be saved on the disk if the
'secrets_encryption_key' path is set in the secret.conf file OR
if a valid systemd generated credential exists.

While loading secrets, identify the decryption method by matching the file
extension of the stored secret against the known array values.
If no matching scheme is found, the secret is skipped. If the encryption
key is changed across restarts, then also the secret driver will fail to load
the secrets from the disk that were encrypted with the former key.

Signed-off-by: Arun Menon <armenon@redhat.com>
---
 src/conf/virsecretobj.c    | 165 ++++++++++++++++++++++++++++++-------
 src/conf/virsecretobj.h    |  18 +++-
 src/secret/secret_driver.c |  23 ++++--
 3 files changed, 166 insertions(+), 40 deletions(-)

diff --git a/src/conf/virsecretobj.c b/src/conf/virsecretobj.c
index a3dd7983bb..5c0b4c751b 100644
--- a/src/conf/virsecretobj.c
+++ b/src/conf/virsecretobj.c
@@ -31,6 +31,10 @@
 #include "virhash.h"
 #include "virlog.h"
 #include "virstring.h"
+#include "virsecret.h"
+#include "virrandom.h"
+#include "vircrypto.h"
+#include "virsecureerase.h"
 
 #define VIR_FROM_THIS VIR_FROM_SECRET
 
@@ -45,6 +49,16 @@ struct _virSecretObj {
     size_t value_size;
 };
 
+typedef struct _virSecretSchemeInfo {
+    const char *suffix;
+    virCryptoCipher cipher;
+} virSecretSchemeInfo;
+
+virSecretSchemeInfo schemeInfo[] = {
+    { ".aes256cbc", VIR_CRYPTO_CIPHER_AES256CBC },
+    { ".base64", -1 },
+};
+
 static virClass *virSecretObjClass;
 static virClass *virSecretObjListClass;
 static void virSecretObjDispose(void *obj);
@@ -323,7 +337,8 @@ virSecretObj *
 virSecretObjListAdd(virSecretObjList *secrets,
                     virSecretDef **newdef,
                     const char *configDir,
-                    virSecretDef **oldDef)
+                    virSecretDef **oldDef,
+                    bool encryptData)
 {
     virSecretObj *obj;
     virSecretDef *objdef;
@@ -363,6 +378,8 @@ virSecretObjListAdd(virSecretObjList *secrets,
     } else {
         /* No existing secret with same UUID,
          * try look for matching usage instead */
+        const char *secretSuffix = ".base64";
+        g_autofree char *encryptionSchemeSuffix = NULL;
         if ((obj = virSecretObjListFindByUsageLocked(secrets,
                                                      (*newdef)->usage_type,
                                                      (*newdef)->usage_id))) {
@@ -379,10 +396,17 @@ virSecretObjListAdd(virSecretObjList *secrets,
             goto cleanup;
 
         /* Generate the possible configFile and secretValueFile strings
-         * using the configDir, uuidstr, and appropriate suffix
+         * using the configDir, uuidstr, and appropriate suffix.
+         * By default, the latest encryption cipher will be used to encrypt secrets.
          */
+
+        if (encryptData) {
+            encryptionSchemeSuffix = g_strdup(schemeInfo[0].suffix);
+        } else {
+            encryptionSchemeSuffix = g_strdup(secretSuffix);
+        }
         if (!(obj->configFile = virFileBuildPath(configDir, uuidstr, ".xml")) ||
-            !(obj->secretValueFile = virFileBuildPath(configDir, uuidstr, ".base64")))
+            !(obj->secretValueFile = virFileBuildPath(configDir, uuidstr, encryptionSchemeSuffix)))
             goto cleanup;
 
         if (virHashAddEntry(secrets->objs, uuidstr, obj) < 0)
@@ -682,15 +706,40 @@ virSecretObjSaveConfig(virSecretObj *obj)
 
 
 int
-virSecretObjSaveData(virSecretObj *obj)
+virSecretObjSaveData(virSecretObj *obj,
+                     bool encryptData,
+                     uint8_t *secretsEncryptionKey,
+                     size_t secretsKeyLen)
 {
     g_autofree char *base64 = NULL;
+    g_autofree uint8_t *secret = NULL;
+    g_autofree uint8_t *encryptedValue = NULL;
+    size_t encryptedValueLen = 0;
+    size_t secretLen = 0;
+    uint8_t iv[16] = { 0 };
 
     if (!obj->value)
         return 0;
 
-    base64 = g_base64_encode(obj->value, obj->value_size);
-
+    if (encryptData && secretsEncryptionKey) {
+        if (virRandomBytes(iv, sizeof(iv)) < 0) {
+            return -1;
+        }
+        if (virCryptoEncryptData(schemeInfo[0].cipher,
+                                 secretsEncryptionKey, secretsKeyLen,
+                                 iv, sizeof(iv),
+                                 (uint8_t *)obj->value, obj->value_size,
+                                 &encryptedValue, &encryptedValueLen) < 0) {
+            return -1;
+        }
+        secretLen = sizeof(iv) + encryptedValueLen;
+        secret = g_new0(uint8_t, secretLen);
+        memcpy(secret, iv, sizeof(iv));
+        memcpy(secret + sizeof(iv), encryptedValue, encryptedValueLen);
+        base64 = g_base64_encode(secret, secretLen);
+    } else {
+        base64 = g_base64_encode(obj->value, obj->value_size);
+    }
     if (virFileRewriteStr(obj->secretValueFile, S_IRUSR | S_IWUSR, base64) < 0)
         return -1;
 
@@ -737,7 +786,10 @@ virSecretObjGetValue(virSecretObj *obj)
 int
 virSecretObjSetValue(virSecretObj *obj,
                      const unsigned char *value,
-                     size_t value_size)
+                     size_t value_size,
+                     bool encryptData,
+                     uint8_t *secretsEncryptionKey,
+                     size_t secretsKeyLen)
 {
     virSecretDef *def = obj->def;
     g_autofree unsigned char *old_value = NULL;
@@ -753,7 +805,10 @@ virSecretObjSetValue(virSecretObj *obj,
     obj->value = g_steal_pointer(&new_value);
     obj->value_size = value_size;
 
-    if (!def->isephemeral && virSecretObjSaveData(obj) < 0)
+    if (!def->isephemeral && virSecretObjSaveData(obj,
+                                                  encryptData,
+                                                  secretsEncryptionKey,
+                                                  secretsKeyLen) < 0)
         goto error;
 
     /* Saved successfully - drop old value */
@@ -807,11 +862,23 @@ virSecretLoadValidateUUID(virSecretDef *def,
 
 
 static int
-virSecretLoadValue(virSecretObj *obj)
+virSecretLoadValue(virSecretObj *obj,
+                   uint8_t *secretsEncryptionKey,
+                   size_t secretsKeyLen)
 {
-    int ret = -1, fd = -1;
+    int ret = -1;
+    VIR_AUTOCLOSE fd = -1;
     struct stat st;
+    size_t i;
+
     g_autofree char *contents = NULL;
+    g_autofree uint8_t *contentsEncrypted = NULL;
+    g_autofree uint8_t *decryptedValue = NULL;
+
+    size_t decryptedValueLen = 0;
+    uint8_t iv[16] = { 0 };
+    uint8_t *ciphertext = NULL;
+    size_t ciphertextLen = 0;
 
     if ((fd = open(obj->secretValueFile, O_RDONLY)) == -1) {
         if (errno == ENOENT) {
@@ -841,25 +908,52 @@ virSecretLoadValue(virSecretObj *obj)
         goto cleanup;
     }
 
-    contents = g_new0(char, st.st_size + 1);
-
-    if (saferead(fd, contents, st.st_size) != st.st_size) {
-        virReportSystemError(errno, _("cannot read '%1$s'"),
-                             obj->secretValueFile);
-        goto cleanup;
+    /* Iterate over the encryption schemes and decrypt the contents
+     * of the file on the disk, by matching the file extension with the encryption
+     * scheme.
+     * If there is no scheme matching the file extension, then that secret is not loaded. */
+
+    for (i = 0; i < G_N_ELEMENTS(schemeInfo); i++) {
+        if (virStringHasSuffix(obj->secretValueFile, schemeInfo[i].suffix)) {
+            contents = g_new0(char, st.st_size + 1);
+            if (saferead(fd, contents, st.st_size) != st.st_size) {
+                virReportSystemError(errno, _("cannot read '%1$s'"),
+                                     obj->secretValueFile);
+                goto cleanup;
+            }
+            contents[st.st_size] = '\0';
+            if (schemeInfo[i].cipher != -1) {
+                contentsEncrypted = g_base64_decode(contents, &obj->value_size);
+                if (sizeof(iv) > obj->value_size) {
+                    virReportError(VIR_ERR_INVALID_SECRET,
+                                   _("Encrypted secret size '%1$zu' is invalid"),
+                                   obj->value_size);
+                    goto cleanup;
+                }
+                memcpy(iv, contentsEncrypted, sizeof(iv));
+                ciphertext = contentsEncrypted + sizeof(iv);
+                ciphertextLen = obj->value_size - sizeof(iv);
+                if (virCryptoDecryptData(schemeInfo[i].cipher,
+                                         secretsEncryptionKey, secretsKeyLen,
+                                         iv, sizeof(iv),
+                                         ciphertext, ciphertextLen,
+                                         &decryptedValue, &decryptedValueLen) < 0) {
+                    goto cleanup;
+                }
+                g_free(obj->value);
+                obj->value = g_steal_pointer(&decryptedValue);
+                obj->value_size = decryptedValueLen;
+            } else {
+                obj->value = g_base64_decode(contents, &obj->value_size);
+            }
+            break;
+        }
     }
-    contents[st.st_size] = '\0';
-
-    VIR_FORCE_CLOSE(fd);
-
-    obj->value = g_base64_decode(contents, &obj->value_size);
-
     ret = 0;
-
  cleanup:
-    if (contents != NULL)
-        memset(contents, 0, st.st_size);
-    VIR_FORCE_CLOSE(fd);
+    virSecureErase(contentsEncrypted, obj->value_size);
+    virSecureErase(contents, st.st_size);
+    virSecureErase(iv, sizeof(iv));
     return ret;
 }
 
@@ -868,7 +962,10 @@ static virSecretObj *
 virSecretLoad(virSecretObjList *secrets,
               const char *file,
               const char *path,
-              const char *configDir)
+              const char *configDir,
+              bool encryptData,
+              uint8_t *secretsEncryptionKey,
+              size_t secretsKeyLen)
 {
     g_autoptr(virSecretDef) def = NULL;
     virSecretObj *obj = NULL;
@@ -879,10 +976,10 @@ virSecretLoad(virSecretObjList *secrets,
     if (virSecretLoadValidateUUID(def, file) < 0)
         return NULL;
 
-    if (!(obj = virSecretObjListAdd(secrets, &def, configDir, NULL)))
+    if (!(obj = virSecretObjListAdd(secrets, &def, configDir, NULL, encryptData)))
         return NULL;
 
-    if (virSecretLoadValue(obj) < 0) {
+    if (virSecretLoadValue(obj, secretsEncryptionKey, secretsKeyLen) < 0) {
         virSecretObjListRemove(secrets, obj);
         g_clear_pointer(&obj, virObjectUnref);
         return NULL;
@@ -894,7 +991,10 @@ virSecretLoad(virSecretObjList *secrets,
 
 int
 virSecretLoadAllConfigs(virSecretObjList *secrets,
-                        const char *configDir)
+                        const char *configDir,
+                        bool encryptData,
+                        uint8_t *secretsEncryptionKey,
+                        size_t secretsKeyLen)
 {
     g_autoptr(DIR) dir = NULL;
     struct dirent *de;
@@ -915,7 +1015,10 @@ virSecretLoadAllConfigs(virSecretObjList *secrets,
         if (!(path = virFileBuildPath(configDir, de->d_name, NULL)))
             continue;
 
-        if (!(obj = virSecretLoad(secrets, de->d_name, path, configDir))) {
+        if (!(obj = virSecretLoad(secrets, de->d_name, path, configDir,
+                                  encryptData,
+                                  secretsEncryptionKey,
+                                  secretsKeyLen))) {
             VIR_ERROR(_("Error reading secret: %1$s"),
                       virGetLastErrorMessage());
             continue;
diff --git a/src/conf/virsecretobj.h b/src/conf/virsecretobj.h
index 17897c5513..2e4d980988 100644
--- a/src/conf/virsecretobj.h
+++ b/src/conf/virsecretobj.h
@@ -51,7 +51,8 @@ virSecretObj *
 virSecretObjListAdd(virSecretObjList *secrets,
                     virSecretDef **newdef,
                     const char *configDir,
-                    virSecretDef **oldDef);
+                    virSecretDef **oldDef,
+                    bool encryptData);
 
 typedef bool
 (*virSecretObjListACLFilter)(virConnectPtr conn,
@@ -86,7 +87,10 @@ int
 virSecretObjSaveConfig(virSecretObj *obj);
 
 int
-virSecretObjSaveData(virSecretObj *obj);
+virSecretObjSaveData(virSecretObj *obj,
+                     bool encryptData,
+                     uint8_t *secretsEncryptionKey,
+                     size_t secretsKeyLen);
 
 virSecretDef *
 virSecretObjGetDef(virSecretObj *obj);
@@ -101,7 +105,10 @@ virSecretObjGetValue(virSecretObj *obj);
 int
 virSecretObjSetValue(virSecretObj *obj,
                      const unsigned char *value,
-                     size_t value_size);
+                     size_t value_size,
+                     bool encryptData,
+                     uint8_t *secretsEncryptionKey,
+                     size_t secretsKeyLen);
 
 size_t
 virSecretObjGetValueSize(virSecretObj *obj);
@@ -112,4 +119,7 @@ virSecretObjSetValueSize(virSecretObj *obj,
 
 int
 virSecretLoadAllConfigs(virSecretObjList *secrets,
-                        const char *configDir);
+                        const char *configDir,
+                        bool encryptData,
+                        uint8_t *secretsEncryptionKey,
+                        size_t secretsKeyLen);
diff --git a/src/secret/secret_driver.c b/src/secret/secret_driver.c
index 9b13772ad3..f25b9ba73f 100644
--- a/src/secret/secret_driver.c
+++ b/src/secret/secret_driver.c
@@ -223,13 +223,17 @@ secretDefineXML(virConnectPtr conn,
         goto cleanup;
 
     if (!(obj = virSecretObjListAdd(driver->secrets, &def,
-                                    driver->configDir, &backup)))
+                                    driver->configDir, &backup,
+                                    driver->config->encryptData)))
         goto cleanup;
     objDef = virSecretObjGetDef(obj);
 
     if (!objDef->isephemeral) {
         if (backup && backup->isephemeral) {
-            if (virSecretObjSaveData(obj) < 0)
+            if (virSecretObjSaveData(obj,
+                                     driver->config->encryptData,
+                                     driver->config->secretsEncryptionKey,
+                                     driver->config->secretsKeyLen) < 0)
                 goto restore_backup;
         }
 
@@ -333,7 +337,10 @@ secretSetValue(virSecretPtr secret,
     if (virSecretSetValueEnsureACL(secret->conn, def) < 0)
         goto cleanup;
 
-    if (virSecretObjSetValue(obj, value, value_size) < 0)
+    if (virSecretObjSetValue(obj, value, value_size,
+                             driver->config->encryptData,
+                             driver->config->secretsEncryptionKey,
+                             driver->config->secretsKeyLen) < 0)
         goto cleanup;
 
     event = virSecretEventValueChangedNew(def->uuid,
@@ -542,7 +549,10 @@ secretStateInitialize(bool privileged,
     if (!(driver->secrets = virSecretObjListNew()))
         goto error;
 
-    if (virSecretLoadAllConfigs(driver->secrets, driver->configDir) < 0)
+    if (virSecretLoadAllConfigs(driver->secrets, driver->configDir,
+                                driver->config->encryptData,
+                                driver->config->secretsEncryptionKey,
+                                driver->config->secretsKeyLen) < 0)
         goto error;
 
     return VIR_DRV_STATE_INIT_COMPLETE;
@@ -564,7 +574,10 @@ secretStateReload(void)
     if (!(driver->config = virSecretDaemonConfigNew(driver->privileged)))
         return -1;
 
-    ignore_value(virSecretLoadAllConfigs(driver->secrets, driver->configDir));
+    ignore_value(virSecretLoadAllConfigs(driver->secrets, driver->configDir,
+                                         driver->config->encryptData,
+                                         driver->config->secretsEncryptionKey,
+                                         driver->config->secretsKeyLen));
 
     return 0;
 }
-- 
2.51.1