unmount most before unshare

diff --git a/functions b/functions
index ddcd97dd99fe7f4ed85ab93ec03694216faf5a9a..e9111fe08e9c72e6640a7cca20dfe1e1f88b9449 100644 (file)
--- a/functions
+++ b/functions
@@ -11,6 +11,10 @@ die() {
     exit 1
 }
 
+beginswith() {
+    [ "$1" != "${1#$2}" ]
+}
+
 # Function to setup subhost name and log file
 subhost_name() {
     CONFIG="$1"

diff --git a/overlay-boot b/overlay-boot
index fc4b8b428e0d7eb1ffc2665b4c3aca5071f550f9..6577cadf387a658b182b8a928ee257ab3274f9cb 100755 (executable)
--- a/overlay-boot
+++ b/overlay-boot
@@ -31,7 +31,19 @@ exithandler() {
 }
 trap "exithandler" 0
 
-CMD="unshare -fp --mount-proc -i -u ip netns exec $NAME chroot $LIVE /bin/sh"
-echo "$CMD"
-env CONFIG="$CONFIG" $INIT | $CMD
-echo "EXITED $CMD"
+# This process has an unshared mount namespace, so we unmount almost
+# everything before chroot. Exceptions are: $LIVE and anything mounted
+# below that, "/run/netns/$NAME" and its parent paths (incidentally
+# including "/" as well) and "/proc".
+sort -rk2,2 < /proc/mounts | while read D P A2 ; do
+    beginswith "$P" "$LIVE" && continue
+    beginswith "/run/netns/$NAME" "$P" && continue
+    [ "$P" = /proc ] && continue
+    umount "$P"
+done
+
+echo "Starting $NAME"
+env CONFIG="$CONFIG" $INIT | \
+    unshare -fp --mount-proc -i -u \
+           ip netns exec $NAME chroot $LIVE /bin/sh
+echo "Exited $NAME"