scripts/entrypoint.sh

@@ -31,10 +31,12 @@ as_user() {
     runuser -u "$user" -- "$@"
   fi
 }
+# Unlink AS THE CUSTOMER, so a parent dir swapped for a symlink between the
+# check and the rm can only reach what the customer could already.
 drop_symlink() {
   if [ -L "$1" ]; then
-    echo "entrypoint: SECURITY: $1 was a symlink to '$(readlink "$1")' - removed" >&2
-    rm -f -- "$1"
+    echo "entrypoint: SECURITY: $1 was a symlink to '$(readlink "$1")' - removing" >&2
+    as_user rm -f -- "$1" || echo "entrypoint: WARNING: could not remove symlink $1" >&2
   fi
 }
 if [ -L /home/$user ] || [ ! -d /home/$user ]; then
@@ -45,9 +47,11 @@ chown -h $user:$user /home/$user
 # app/ may legitimately be a symlink (releases/current deploys): it is left
 # alone, and every root-side operation on it below runs as the customer.
 drop_symlink /home/$user/logs
-if [ -d /home/$user/logs ]; then
-  # nginx opens its logs here as root; find without -L never follows links.
-  find /home/$user/logs -xdev -type l -print0 2>/dev/null | while IFS= read -r -d '' l; do drop_symlink "$l"; done
+if [ -d /home/$user/logs ] && [ ! -L /home/$user/logs ]; then
+  # nginx opens its logs here as root. As the customer, find without -L never
+  # follows symlinks; -delete unlinks them.
+  as_user find /home/$user/logs -xdev -type l \
+    -printf 'entrypoint: SECURITY: %p was a symlink to %l - removed\n' -delete >&2 || true
 fi
 
 as_user mkdir -p /home/$user/app /home/$user/logs/nginx /home/$user/logs/nodejs