fix: only delete SSL files generated by us

apps/emqx/src/emqx_tls_lib.erl

@@ -319,11 +319,10 @@ delete_old_file(New, Old) when New =:= Old -> ok;
 delete_old_file(_New, _Old = undefined) ->
     ok;
 delete_old_file(_New, Old) ->
-    case filelib:is_regular(Old) andalso file:delete(Old) of
+    case is_generated_file(Old) andalso filelib:is_regular(Old) andalso file:delete(Old) of
         ok ->
             ok;
-        %% already deleted
-        false ->
+        false -> %% the file is not generated by us, or it is already deleted
             ok;
         {error, Reason} ->
             ?SLOG(error, #{msg => "failed_to_delete_ssl_file", file_path => Old, reason => Reason})
@@ -397,6 +396,12 @@ save_pem_file(Dir, Key, Pem, DryRun) ->
 %% the filename is prefixed by the option name without the 'file' part
 %% and suffixed with the first 8 byets the PEM content's md5 checksum.
 %% e.g. key-1234567890abcdef, cert-1234567890abcdef, and cacert-1234567890abcdef
+is_generated_file(Filename) ->
+    case string:split(filename:basename(Filename), "-") of
+        [_Name, Suffix] -> is_hex_str(Suffix);
+        _ -> false
+    end.
+
 pem_file_name(Dir, Key, Pem) ->
     <<CK:8/binary, _/binary>> = crypto:hash(md5, Pem),
     Suffix = hex_str(CK),
@@ -406,6 +411,19 @@ pem_file_name(Dir, Key, Pem) ->
 pem_dir(Dir) ->
     filename:join([emqx:mutable_certs_dir(), Dir]).
 
+is_hex_str(HexStr) ->
+    try is_hex_str2(ensure_str(HexStr))
+    catch throw: not_hex -> false
+    end.
+
+is_hex_str2(HexStr) ->
+    _ = [case S of
+            S when S >= $0, S =< $9 -> S;
+            S when S >= $a, S =< $f -> S;
+            _ -> throw(not_hex)
+         end || S <- HexStr],
+    true.
+
 hex_str(Bin) ->
     iolist_to_binary([io_lib:format("~2.16.0b", [X]) || <<X:8>> <= Bin]).
 

apps/emqx/test/emqx_tls_lib_tests.erl

@@ -143,6 +143,22 @@ ssl_files_save_delete_test() ->
     ok = emqx_tls_lib:delete_ssl_files(Dir, undefined, SSL),
     ok.
 
+ssl_files_handle_non_generated_file_test() ->
+    TmpKeyFile = <<"my-key-file.pem">>,
+    KeyFileContent = bin(test_key()),
+    ok = file:write_file(TmpKeyFile, KeyFileContent),
+    ?assert(filelib:is_regular(TmpKeyFile)),
+    SSL0 = #{<<"keyfile">> => TmpKeyFile},
+    Dir = filename:join(["/tmp", "ssl-test-dir-00"]),
+    {ok, SSL2} = emqx_tls_lib:ensure_ssl_files(Dir, SSL0),
+    File1 = maps:get(<<"keyfile">>, SSL2),
+    %% verify the filename and path is not changed by the emqx_tls_lib
+    ?assertEqual(TmpKeyFile, File1),
+    ok = emqx_tls_lib:delete_ssl_files(Dir, undefined, SSL2),
+    %% verify the file is not delete and not changed, because it is not generated by
+    %% emqx_tls_lib
+    ?assertEqual({ok, KeyFileContent}, file:read_file(TmpKeyFile)).
+
 ssl_file_replace_test() ->
     SSL0 = #{<<"keyfile">> => bin(test_key())},
     SSL1 = #{<<"keyfile">> => bin(test_key2())},