zlib: Don't allow clients to save compressed data directly.

This way clients can't try to exploit uncompression bugs in zlib/bzlib.

--HG--
branch : HEAD

diff --git a/src/plugins/zlib/zlib-plugin.c b/src/plugins/zlib/zlib-plugin.c
index 507b3f2220da4671576ab3b0357cd19f42cc791b..c196408ebedcec0d0f30b0b3c075608bf13f48ab 100644 (file)
--- a/src/plugins/zlib/zlib-plugin.c
+++ b/src/plugins/zlib/zlib-plugin.c
@@ -29,6 +29,12 @@ struct zlib_handler {
        struct istream *(*create_istream)(int fd);
 };
 
+struct zlib_transaction_context {
+       union mailbox_transaction_module_context module_ctx;
+
+       struct mail *tmp_mail;
+};
+
 const char *zlib_plugin_version = PACKAGE_VERSION;
 
 static void (*zlib_next_hook_mail_storage_created)
@@ -167,6 +173,93 @@ zlib_maildir_mail_alloc(struct mailbox_transaction_context *t,
        return _mail;
 }
 
+static struct mailbox_transaction_context *
+zlib_mailbox_transaction_begin(struct mailbox *box,
+                              enum mailbox_transaction_flags flags)
+{
+       union mailbox_module_context *zbox = ZLIB_CONTEXT(box);
+       struct mailbox_transaction_context *t;
+       struct zlib_transaction_context *zt;
+
+       t = zbox->super.transaction_begin(box, flags);
+
+       zt = i_new(struct zlib_transaction_context, 1);
+
+       MODULE_CONTEXT_SET(t, zlib_storage_module, zt);
+       return t;
+}
+
+static void
+zlib_mailbox_transaction_rollback(struct mailbox_transaction_context *t)
+{
+       union mailbox_module_context *zbox = ZLIB_CONTEXT(t->box);
+       struct zlib_transaction_context *zt = ZLIB_CONTEXT(t);
+
+       if (zt->tmp_mail != NULL)
+               mail_free(&zt->tmp_mail);
+
+       zbox->super.transaction_rollback(t);
+       i_free(zt);
+}
+
+static int
+zlib_mailbox_transaction_commit(struct mailbox_transaction_context *t,
+                               struct mail_transaction_commit_changes *changes_r)
+{
+       union mailbox_module_context *zbox = ZLIB_CONTEXT(t->box);
+       struct zlib_transaction_context *zt = ZLIB_CONTEXT(t);
+       int ret;
+
+       if (zt->tmp_mail != NULL)
+               mail_free(&zt->tmp_mail);
+
+       ret = zbox->super.transaction_commit(t, changes_r);
+       i_free(zt);
+       return ret;
+}
+
+static int
+zlib_mail_save_begin(struct mail_save_context *ctx, struct istream *input)
+{
+       struct mailbox_transaction_context *t = ctx->transaction;
+       struct zlib_transaction_context *zt = ZLIB_CONTEXT(t);
+       union mailbox_module_context *zbox = ZLIB_CONTEXT(t->box);
+
+       if (ctx->dest_mail == NULL) {
+               if (zt->tmp_mail == NULL) {
+                       zt->tmp_mail = mail_alloc(t, MAIL_FETCH_PHYSICAL_SIZE,
+                                                 NULL);
+               }
+               ctx->dest_mail = zt->tmp_mail;
+       }
+
+       return zbox->super.save_begin(ctx, input);
+}
+
+static int zlib_mail_save_finish(struct mail_save_context *ctx)
+{
+       struct mailbox *box = ctx->transaction->box;
+       union mailbox_module_context *zbox = ZLIB_CONTEXT(box);
+       struct istream *input;
+       unsigned int i;
+
+       if (zbox->super.save_finish(ctx) < 0)
+               return -1;
+
+       if (mail_get_stream(ctx->dest_mail, NULL, NULL, &input) < 0)
+               return -1;
+
+       for (i = 0; i < N_ELEMENTS(zlib_handlers); i++) {
+               if (zlib_handlers[i].is_compressed(input)) {
+                       mail_storage_set_error(box->storage,
+                               MAIL_ERROR_NOTPOSSIBLE,
+                               "Saving mails compressed by client isn't supported");
+                       return -1;
+               }
+       }
+       return 0;
+}
+
 static void zlib_maildir_open_init(struct mailbox *box)
 {
        union mailbox_module_context *zbox;
@@ -174,6 +267,11 @@ static void zlib_maildir_open_init(struct mailbox *box)
        zbox = p_new(box->pool, union mailbox_module_context, 1);
        zbox->super = box->v;
        box->v.mail_alloc = zlib_maildir_mail_alloc;
+       box->v.transaction_begin = zlib_mailbox_transaction_begin;
+       box->v.transaction_rollback = zlib_mailbox_transaction_rollback;
+       box->v.transaction_commit = zlib_mailbox_transaction_commit;
+       box->v.save_begin = zlib_mail_save_begin;
+       box->v.save_finish = zlib_mail_save_finish;
 
        MODULE_CONTEXT_SET_SELF(box, zlib_storage_module, zbox);
 }
@@ -242,13 +340,11 @@ static void zlib_mail_storage_created(struct mail_storage *storage)
 
 void zlib_plugin_init(void)
 {
-       zlib_next_hook_mail_storage_created =
-               hook_mail_storage_created;
+       zlib_next_hook_mail_storage_created = hook_mail_storage_created;
        hook_mail_storage_created = zlib_mail_storage_created;
 }
 
 void zlib_plugin_deinit(void)
 {
-       hook_mail_storage_created =
-               zlib_next_hook_mail_storage_created;
+       hook_mail_storage_created = zlib_next_hook_mail_storage_created;
 }