programs: sandbox: omit media dirs by default, and implement --sane-sandbox-autodetect for programs which are liable to load data from paths

hosts/common/programs/mpv.nix

@@ -63,7 +63,9 @@ in
     });
 
     sandbox.method = "bwrap";
-    # sandbox.method = "firejail";  #< fails on moby
+    sandbox.extraConfig = [
+      "--sane-sandbox-autodetect"
+    ];
 
     persist.byStore.plaintext = [ ".local/state/mpv/watch_later" ];
     fs.".config/mpv/input.conf".symlink.text = let

modules/programs/default.nix

@@ -40,24 +40,12 @@ let
       let
         makeSandboxed = pkgs.callPackage ./make-sandboxed.nix { sane-sandboxed = config.sane.sandboxHelper; };
         vpn = lib.findSingle (v: v.default) null null (builtins.attrValues config.sane.vpn);
-        # TODO: restrict access to these media paths a bit more.
-        #       maybe mount them user=nobody and restrict based on group?
-        mediaHomePaths = [
-          "Books"
-          "Music"
-          "Pictures"
-          "Videos"
-          "tmp"
-        ];
-        mediaRootPaths = [
-          "/mnt/servo-media"
-        ];
       in
         makeSandboxed {
           inherit pkgName package;
           inherit (sandbox) binMap method extraConfig;
           vpn = if net == "vpn" then vpn else null;
-          allowedHomePaths = builtins.attrNames fs ++ builtins.attrNames persist.byPath ++ mediaHomePaths;
+          allowedHomePaths = builtins.attrNames fs ++ builtins.attrNames persist.byPath;
           allowedRootPaths = [
             "/nix/store"
             "/bin/sh"
@@ -72,7 +60,7 @@ let
             "/run/user"  #< particularly /run/user/$id/wayland-1, pulse, etc.
             "/run/secrets/home"
             # "/dev/dri"  #< fix non-fatal "libEGL warning: wayland-egl: could not open /dev/dri/renderD128" (geary)
-          ] ++ mediaRootPaths ++ sandbox.extraPaths;
+          ] ++ sandbox.extraPaths;
         }
   );
   pkgSpec = with lib; types.submodule ({ config, name, ... }: {

modules/programs/sane-sandboxed

@@ -3,6 +3,7 @@
 test -n "$SANE_SANDBOX_DEBUG" && set -x
 
 cliArgs=()
+autodetect=
 profilesNamed=()
 rootPaths=()
 homePaths=()
@@ -67,21 +68,28 @@ parseArgs() {
         method="$1"
         shift
         ;;
+      (--sane-sandbox-autodetect)
+        # autodetect: crawl the CLI program's args & bind any which look like paths into the sandbox.
+        # this is handy for e.g. media players or document viewers.
+        # it's best combined with some two-tiered thing.
+        #   e.g. first drop to the broadest path set of interest (Music,Videos,tmp, ...), then drop via autodetect.
+        autodetect=1
+        ;;
       (--sane-sandbox-dns)
         # N.B.: these named temporary variables ensure that `set -x` causes $1 to be printed
         _dns="$1"
-        dns+=("$_dns")
         shift
+        dns+=("$_dns")
         ;;
       (--sane-sandbox-firejail-arg)
         _fjFlag="$1"
-        firejailFlags+=("$_fjFlag")
         shift
+        firejailFlags+=("$_fjFlag")
         ;;
       (--sane-sandbox-bwrap-arg)
         _bwrapFlag="$1"
-        bwrapFlags+=("$_bwrapFlag")
         shift
+        bwrapFlags+=("$_bwrapFlag")
         ;;
       (--sane-sandbox-net)
         net="$1"
@@ -89,13 +97,13 @@ parseArgs() {
         ;;
       (--sane-sandbox-home-path)
         _path="$1"
-        homePaths+=("$_path")
         shift
+        homePaths+=("$_path")
         ;;
       (--sane-sandbox-path)
         _path="$1"
-        rootPaths+=("$_path")
         shift
+        rootPaths+=("$_path")
         ;;
       (--sane-sandbox-profile)
         tryLoadProfileByName "$1"
@@ -175,7 +183,7 @@ bwrapIngestProfile() {
 # WIP
 
 bwrapExec() {
-  PATH="$PATH:@bubblewrap@/bin" exec bwrap --dev /dev --proc /proc "${bwrapFlags[@]}" -- "${cliArgs[@]}"
+  PATH="$PATH:@bubblewrap@/bin" exec bwrap --dev /dev --proc /proc --tmpfs /tmp "${bwrapFlags[@]}" -- "${cliArgs[@]}"
 }
 
 
@@ -197,6 +205,17 @@ for _path in "${homePaths[@]}"; do
   "$method"IngestHomePath "$_path"
 done
 
+if [ -n "$autodetect" ]; then
+  _pwd=$(pwd)
+  for _arg in "${cliArgs[@]}"; do
+    if [[ "$_arg" == "/*" ]]; then
+      test -e "$_arg" && "$method"IngestRootPath "$_arg"
+    elif test -e "$_pwd/$_arg"; then
+      "$method"IngestRootPath "$_pwd/$_arg"
+    fi
+  done
+fi
+
 if [ -n "$net" ]; then
   "$method"IngestNet "$net"
 fi