[pve-devel] [PATCH proxmox-backup-qemu] fix #2866: invalidate bitmap on crypt_mode change

["Fabian Grünbichler" <f.gruenbichler@proxmox.com>]

signed and plain backups share chunks, so bitmap reusal is okay for
those combinations. switching from encrypted to not encrypted or
vice-versa could have pretty fatal consequences - either referencing
plain-text chunks in 'encrypted' backups, or referencing encrypted
chunks in 'unencrypted' backups without still having the corresponding
keys..

Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
---

Notes:
    requires recent proxmox-backup with public lookup_file_info

 src/backup.rs   |  3 ++-
 src/commands.rs | 35 +++++++++++++++++++++++++++++++++--
 2 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/src/backup.rs b/src/backup.rs
index 717e099..b8108ef 100644
--- a/src/backup.rs
+++ b/src/backup.rs
@@ -202,7 +202,8 @@ impl BackupTask {
         device_name: String,
         size: u64,
     ) -> bool {
-        check_last_incremental_csum(self.last_manifest(), device_name, size)
+        check_last_incremental_csum(self.last_manifest(), &device_name, size)
+            && check_last_encryption_mode(self.last_manifest(), &device_name, self.crypt_mode)
     }
 
     pub async fn register_image(
diff --git a/src/commands.rs b/src/commands.rs
index 6f26324..8d8f2a7 100644
--- a/src/commands.rs
+++ b/src/commands.rs
@@ -80,7 +80,7 @@ pub(crate) async fn add_config(
 
 pub(crate) fn check_last_incremental_csum(
     manifest: Option<Arc<BackupManifest>>,
-    device_name: String,
+    device_name: &str,
     device_size: u64,
 ) -> bool {
 
@@ -91,12 +91,43 @@ pub(crate) fn check_last_incremental_csum(
 
     let archive_name = format!("{}.img.fidx", device_name);
 
-    match PREVIOUS_CSUMS.lock().unwrap().get(&device_name) {
+    match PREVIOUS_CSUMS.lock().unwrap().get(device_name) {
         Some(csum) => manifest.verify_file(&archive_name, &csum, device_size).is_ok(),
         None => false,
     }
 }
 
+pub(crate) fn check_last_encryption_mode(
+    manifest: Option<Arc<BackupManifest>>,
+    device_name: &str,
+    crypt_mode: CryptMode,
+) -> bool {
+
+    let manifest = match manifest {
+        Some(ref manifest) => manifest,
+        None => return false,
+    };
+
+    let archive_name = format!("{}.img.fidx", device_name);
+    match manifest.lookup_file_info(&archive_name) {
+        Ok(file) => {
+            eprintln!("device {} last mode: {:?} current mode {:?}", device_name, file.crypt_mode, crypt_mode);
+            match file.crypt_mode {
+                CryptMode::Encrypt => match crypt_mode {
+                    CryptMode::Encrypt => true,
+                    _ => false,
+                },
+                CryptMode::SignOnly | CryptMode::None => match crypt_mode {
+                    CryptMode::Encrypt => false,
+                    _ => true,
+                },
+            }
+        },
+        _ => false,
+    }
+}
+
+
 pub(crate) async fn register_image(
     client: Arc<BackupWriter>,
     crypt_config: Option<Arc<CryptConfig>>,
-- 
2.20.1