Remove world-writability from per-user directories

'nix-daemon' now creates subdirectories for users when they first
connect.

Fixes #509 (CVE-2019-17365).
Should also fix #3127.

(cherry picked from commit 5a303093dcae1e5ce9212616ef18f2ca51020b0d)

3 files changed, 4 insertions, 32 deletions

diff --git a/scripts/install-multi-user.sh b/scripts/install-multi-user.sh
index a41309e930b5..2ebaa1abaff6 100644
--- a/scripts/install-multi-user.sh
+++ b/scripts/install-multi-user.sh
@@ -529,16 +529,15 @@ create_build_users() {
 }
 
 create_directories() {
+    # FIXME: remove all of this because it duplicates LocalStore::LocalStore().
+
     _sudo "to make the basic directory structure of Nix (part 1)" \
-          mkdir -pv -m 0755 /nix /nix/var /nix/var/log /nix/var/log/nix /nix/var/log/nix/drvs /nix/var/nix{,/db,/gcroots,/profiles,/temproots,/userpool}
+          mkdir -pv -m 0755 /nix /nix/var /nix/var/log /nix/var/log/nix /nix/var/log/nix/drvs /nix/var/nix{,/db,/gcroots,/profiles,/temproots,/userpool} /nix/var/nix/{gcroots,profiles}/per-user
 
     _sudo "to make the basic directory structure of Nix (part 2)" \
-          mkdir -pv -m 1777 /nix/var/nix/{gcroots,profiles}/per-user
-
-    _sudo "to make the basic directory structure of Nix (part 3)" \
           mkdir -pv -m 1775 /nix/store
 
-    _sudo "to make the basic directory structure of Nix (part 4)" \
+    _sudo "to make the basic directory structure of Nix (part 3)" \
           chgrp "$NIX_BUILD_GROUP_NAME" /nix/store
 
     _sudo "to set up the root user's profile (part 1)" \
diff --git a/scripts/nix-profile-daemon.sh.in b/scripts/nix-profile-daemon.sh.in
index 23da5e8559eb..3e138ac42499 100644
--- a/scripts/nix-profile-daemon.sh.in
+++ b/scripts/nix-profile-daemon.sh.in
@@ -5,12 +5,6 @@ __ETC_PROFILE_NIX_SOURCED=1
 export NIX_USER_PROFILE_DIR="@localstatedir@/nix/profiles/per-user/$USER"
 export NIX_PROFILES="@localstatedir@/nix/profiles/default $HOME/.nix-profile"
 
-# Set up the per-user profile.
-mkdir -m 0755 -p $NIX_USER_PROFILE_DIR
-if ! test -O "$NIX_USER_PROFILE_DIR"; then
-    echo "WARNING: bad ownership on $NIX_USER_PROFILE_DIR" >&2
-fi
-
 if test -w $HOME; then
   if ! test -L $HOME/.nix-profile; then
       if test "$USER" != root; then
@@ -26,13 +20,6 @@ if test -w $HOME; then
       echo "https://nixos.org/channels/nixpkgs-unstable nixpkgs" > $HOME/.nix-channels
   fi
 
-  # Create the per-user garbage collector roots directory.
-  NIX_USER_GCROOTS_DIR=@localstatedir@/nix/gcroots/per-user/$USER
-  mkdir -m 0755 -p $NIX_USER_GCROOTS_DIR
-  if ! test -O "$NIX_USER_GCROOTS_DIR"; then
-      echo "WARNING: bad ownership on $NIX_USER_GCROOTS_DIR" >&2
-  fi
-
   # Set up a default Nix expression from which to install stuff.
   if [ ! -e $HOME/.nix-defexpr -o -L $HOME/.nix-defexpr ]; then
       rm -f $HOME/.nix-defexpr
diff --git a/scripts/nix-profile.sh.in b/scripts/nix-profile.sh.in
index 85f1d6e5dae2..7f9b5877a8dd 100644
--- a/scripts/nix-profile.sh.in
+++ b/scripts/nix-profile.sh.in
@@ -9,12 +9,6 @@ if [ -n "$HOME" ] && [ -n "$USER" ]; then
 
     NIX_USER_PROFILE_DIR=@localstatedir@/nix/profiles/per-user/$USER
 
-    mkdir -m 0755 -p "$NIX_USER_PROFILE_DIR"
-
-    if [ "$(stat --printf '%u' "$NIX_USER_PROFILE_DIR")" != "$(id -u)" ]; then
-        echo "Nix: WARNING: bad ownership on "$NIX_USER_PROFILE_DIR", should be $(id -u)" >&2
-    fi
-
     if [ -w "$HOME" ]; then
         if ! [ -L "$NIX_LINK" ]; then
             echo "Nix: creating $NIX_LINK" >&2
@@ -33,14 +27,6 @@ if [ -n "$HOME" ] && [ -n "$USER" ]; then
             echo "https://nixos.org/channels/nixpkgs-unstable nixpkgs" > "$HOME/.nix-channels"
         fi
 
-        # Create the per-user garbage collector roots directory.
-        __user_gcroots=@localstatedir@/nix/gcroots/per-user/"$USER"
-        mkdir -m 0755 -p "$__user_gcroots"
-        if [ "$(stat --printf '%u' "$__user_gcroots")" != "$(id -u)" ]; then
-            echo "Nix: WARNING: bad ownership on $__user_gcroots, should be $(id -u)" >&2
-        fi
-        unset __user_gcroots
-
         # Set up a default Nix expression from which to install stuff.
         __nix_defexpr="$HOME"/.nix-defexpr
         [ -L "$__nix_defexpr" ] && rm -f "$__nix_defexpr"