optionally use image driver for squashfs and gocryptfs in setuid mode

Signed-off-by: Dave Dykstra <2129743+DrDaveD@users.noreply.github.com>

.github/workflows/ci.yml

@@ -322,10 +322,18 @@ jobs:
 
       - name: Fetch deps
         if: env.run_tests
-        run: sudo apt-get -q update && sudo DEBIAN_FRONTEND=noninteractive apt-get install -y build-essential uidmap squashfs-tools squashfuse fuse-overlayfs fakeroot fuse2fs libseccomp-dev cryptsetup dbus-user-session
+        run: |
+          set -e
+          sudo apt-get -q update
+          sudo DEBIAN_FRONTEND=noninteractive apt-get install -y build-essential uidmap squashfs-tools squashfuse fuse-overlayfs fakeroot fuse2fs libseccomp-dev cryptsetup dbus-user-session
+          sudo DEBIAN_FRONTEND=noninteractive apt-get install -y autoconf automake libtool pkg-config libfuse3-dev zlib1g-dev
 
-      - name: Fetch gocryptfs
-        run: wget -O gocryptfs.tar.gz https://github.com/rfjakob/gocryptfs/releases/download/v2.3/gocryptfs_v2.3_linux-static_amd64.tar.gz && sudo tar xzvf gocryptfs.tar.gz -C /usr/local/bin gocryptfs
+      - name: Download, compile, and install dependent packages
+        run: |
+          set -ex
+          mlocal/scripts/download-dependencies .
+          mlocal/scripts/compile-dependencies
+          sudo cp gocryptfs*/gocryptfs squashfuse*/squashfuse_ll /usr/local/bin
 
       # The fuse-overlayfs version from ubuntu-22.04, 1.7, is buggy,
       # so update to version 1.9

CHANGELOG.md

@@ -9,6 +9,16 @@ For older changes see the [archived Singularity change log](https://github.com/a
 
 ### Changed defaults / behaviours
 
+- In setuid privileged mode, if `allow setuid-mount squashfs = no` then
+  the squashfuse image driver will be used to mount squash images
+  instead of the kernel squashfs driver.  This eliminates the
+  vulnerability of using a kernel filesystem driver to mount a file
+  writable by an unprivileged user.  Likewise, if
+  `allow setuid-mount encrypted = no` then the unprivileged gocryptfs
+  format will be used for encrypting SIF files instead of the kernel
+  device-mapper.  If a SIF file was encrypted using the gocryptfs
+  format, it can now be mounted in setuid mode in addition to
+  non-setuid mode.
 - `--cwd` is now the preferred form of the flag for setting the container's
   working directory, though `--pwd` is still supported for compatibility.
 - When building RPM, we will now use `/var/lib/apptainer` (rather than

INSTALL.md

@@ -28,6 +28,7 @@ sudo apt-get install -y \
     fuse-overlayfs \
     fakeroot \
     cryptsetup \
+    tzdata \
     curl wget git
 ```
 
@@ -182,7 +183,7 @@ Instructions for installing it from source follow here.
 First, make sure that additional required packages are installed.  On Debian:
 
 ```sh
-apt-get install -y autoconf automake libtool pkg-config libfuse-dev zlib1g-dev
+apt-get install -y autoconf automake libtool pkg-config libfuse3-dev zlib1g-dev
 ```
 
 On CentOS/RHEL:

dist/debian/control

@@ -19,7 +19,7 @@ Build-Depends:
  automake,
  libtool,
  pkg-config,
- libfuse-dev,
+ libfuse3-dev,
  zlib1g-dev
 Standards-Version: 3.9.8
 Homepage: http://apptainer.org

dist/debian/rules

@@ -64,35 +64,21 @@ export APPTAINER_CACHEDIR=$(pkgdir)/var/lib/apptainer/cache
 	dh $@  --with=autoreconf
 
 override_dh_auto_configure:
-	@SQUASHFUSETGZ="`echo debian/squashfuse-*.tar.gz`"; \
-	  if [ -f "$$SQUASHFUSETGZ" ]; then \
-	    set -x; \
-	    tar -C debian -xf $$SQUASHFUSETGZ; \
-	    cd $${SQUASHFUSETGZ%.tar.gz}; \
-	    ./autogen.sh; \
-	    FLAGS=-std=c99 ./configure --enable-multithreading; \
-	    make squashfuse_ll; \
-	  fi
-	@export PATH=$(GOROOT)/bin:$$PATH; \
+	@export GOPATH=$(GOROOT)/bin PATH=$(GOROOT)/bin:$$PATH GOCACHE=$(GOCACHE); \
+	  set -ex; \
 	  if ! ./mlocal/scripts/check-min-go-version go $(MINGO_VERSION); then \
-	    set -e; \
 	    if [ -d $(GOROOT) ]; then rm -rf $(GOROOT); fi; \
 	    mkdir -p $(GOROOT); \
 	    HERE=$$PWD; \
 	    cd $(GOROOT)/..; \
 	    tar -xf $$HERE/debian/go$(MINGO_VERSION).src.tar.gz; \
 	    cd go/src; \
-	    GOCACHE=$(GOCACHE) ./make.bash; \
-	  fi
-	@GOCRYPTFSTGZ="`echo debian/gocryptfs-*.tar.gz`"; \
-	  if [ -f "$$GOCRYPTFSTGZ" ]; then \
-	    set -x; \
-	    tar -C debian -xf $$GOCRYPTFSTGZ; \
-	    cd $${GOCRYPTFSTGZ%.tar.gz}; \
-	    export GOCACHE=$(GOCACHE); \
-	    export GOPATH=$(GOROOT)/bin; \
-	    PATH=$(GOROOT)/bin:$$PATH ./build-without-openssl.bash; \
-	  fi
+	    ./make.bash; \
+	    cd $$HERE; \
+	  fi; \
+	  cd debian; \
+	  ../mlocal/scripts/compile-dependencies; \
+	  cd ..
 ifneq ($(NEW_VERSION),)
 	$(warning "Setting new version in debian changelog: $(NEW_VERSION)")
 	@debchange -v $(NEW_VERSION)$(VERSION_POSTFIX) "Version $(NEW_VERSION)" && debchange -m -r ""

dist/rpm/apptainer.spec.in

@@ -151,22 +151,6 @@ Provides the optional setuid-root portion of Apptainer.
 %endif
 
 %build
-%if "%{?gocryptfs_version}" != ""
-pushd ../gocryptfs-%{gocryptfs_version}
-if [ ! -d vendor ]; then
-    (
-    export GOPATH="`pwd`/gopath"
-    go mod vendor
-    go clean -modcache
-    )
-fi
-# GOPROXY=off makes sure we fail instead of making network requests
-# the -B ldflags prevent rpm complaints about "No build ID note found"
-CGO_ENABLED=0 GOPROXY=off ./build.bash -mod=vendor -tags without_openssl \
-    -ldflags="-X main.GitVersion=%{gocryptfs_version} -B 0x`head -c20 /dev/urandom|od -An -tx1|tr -d ' \n'`" 
-popd
-%endif
-
 %if "%{?squashfuse_version}" != ""
 pushd ../squashfuse-%{squashfuse_version}
 ./autogen.sh
@@ -189,6 +173,22 @@ if ! ./mlocal/scripts/check-min-go-version go $GOVERSION; then
 fi
 %endif
 
+%if "%{?gocryptfs_version}" != ""
+pushd ../gocryptfs-%{gocryptfs_version}
+if [ ! -d vendor ]; then
+    (
+    export GOPATH="`pwd`/gopath"
+    go mod vendor
+    go clean -modcache
+    )
+fi
+# GOPROXY=off makes sure we fail instead of making network requests
+# the -B ldflags prevent rpm complaints about "No build ID note found"
+CGO_ENABLED=0 GOPROXY=off ./build.bash -mod=vendor -tags without_openssl \
+    -ldflags="-X main.GitVersion=%{gocryptfs_version} -B 0x`head -c20 /dev/urandom|od -An -tx1|tr -d ' \n'`" 
+popd
+%endif
+
 # Not all of these parameters currently have an effect, but they might be
 #  used someday.  They are the same parameters as in the configure macro.
 ./mconfig %{?mconfig_opts} -V %{version}-%{release} --with-suid \

e2e/config/config.go

@@ -123,6 +123,8 @@ func (c *configTests) prepImages(t *testing.T) (cleanup func(t *testing.T)) {
 	return cleanup
 }
 
+const findsquash = "pstree $PPID|grep squashfuse"
+
 //nolint:maintidx
 func (c configTests) configGlobal(t *testing.T) {
 	cleanup := c.prepImages(t)
@@ -506,6 +508,14 @@ func (c configTests) configGlobal(t *testing.T) {
 			directiveValue: "no",
 			exit:           255,
 		},
+		{
+			name:           "AllowSetuidMountEncryptedNoUnpriv",
+			argv:           []string{"--pem-path", c.pemPrivate, c.encryptedUnprivImage, "true"},
+			profile:        e2e.UserProfile,
+			directive:      "allow setuid-mount encrypted",
+			directiveValue: "no",
+			exit:           0,
+		},
 		{
 			name:           "AllowSetuidMountEncryptedNoUserns",
 			argv:           []string{"--pem-path", c.pemPrivate, c.encryptedUnprivImage, "true"},
@@ -522,77 +532,85 @@ func (c configTests) configGlobal(t *testing.T) {
 			directiveValue: "yes",
 			exit:           0,
 		},
+		{
+			name:           "AllowSetuidMountEncryptedYesUnpriv",
+			argv:           []string{"--pem-path", c.pemPrivate, c.encryptedUnprivImage, "true"},
+			profile:        e2e.UserProfile,
+			directive:      "allow setuid-mount encrypted",
+			directiveValue: "yes",
+			exit:           0,
+		},
 		{
 			name:           "AllowSetuidMountSquashfsNo",
-			argv:           []string{c.squashfsImage, "true"},
+			argv:           []string{c.squashfsImage, "sh", "-c", findsquash},
 			profile:        e2e.UserProfile,
 			directive:      "allow setuid-mount squashfs",
 			directiveValue: "no",
-			exit:           255,
+			exit:           0,
 		},
 		{
 			name:           "AllowSetuidMountSquashfsNoSif",
-			argv:           []string{c.sifImage, "true"},
+			argv:           []string{c.sifImage, "sh", "-c", findsquash},
 			profile:        e2e.UserProfile,
 			directive:      "allow setuid-mount squashfs",
 			directiveValue: "no",
-			exit:           255,
+			exit:           0,
 		},
 		{
 			name:           "AllowSetuidMountSquashfsNoBind",
-			argv:           []string{"-B", c.squashfsImage + ":/sqsh:image-src=/", c.sifImage, "true"},
+			argv:           []string{"-B", c.squashfsImage + ":/sqsh:image-src=/", c.sifImage, "sh", "-c", findsquash},
 			profile:        e2e.UserProfile,
 			directive:      "allow setuid-mount squashfs",
 			directiveValue: "no",
-			exit:           255,
+			exit:           0,
 		},
 		{
 			name:           "AllowSetuidMountSquashfsNoUserns",
-			argv:           []string{c.squashfsImage, "true"},
+			argv:           []string{c.squashfsImage, "sh", "-c", findsquash},
 			profile:        e2e.UserNamespaceProfile,
 			directive:      "allow setuid-mount squashfs",
 			directiveValue: "no",
 			exit:           0,
 		},
 		{
 			name:           "AllowSetuidMountSquashfsNoUsernsSif",
-			argv:           []string{c.sifImage, "true"},
+			argv:           []string{c.sifImage, "sh", "-c", findsquash},
 			profile:        e2e.UserNamespaceProfile,
 			directive:      "allow setuid-mount squashfs",
 			directiveValue: "no",
 			exit:           0,
 		},
 		{
 			name:           "AllowSetuidMountSquashfsNoUsernsBind",
-			argv:           []string{"-B", c.squashfsImage + ":/sqsh:image-src=/", c.sifImage, "true"},
+			argv:           []string{"-B", c.squashfsImage + ":/sqsh:image-src=/", c.sifImage, "sh", "-c", findsquash},
 			profile:        e2e.UserNamespaceProfile,
 			directive:      "allow setuid-mount squashfs",
 			directiveValue: "no",
 			exit:           0,
 		},
 		{
 			name:           "AllowSetuidMountSquashfsYes",
-			argv:           []string{c.squashfsImage, "true"},
+			argv:           []string{c.squashfsImage, "sh", "-c", findsquash},
 			profile:        e2e.UserProfile,
 			directive:      "allow setuid-mount squashfs",
 			directiveValue: "yes",
-			exit:           0,
+			exit:           1,
 		},
 		{
 			name:           "AllowSetuidMountSquashfsYesSif",
-			argv:           []string{c.sifImage, "true"},
+			argv:           []string{c.sifImage, "sh", "-c", findsquash},
 			profile:        e2e.UserProfile,
 			directive:      "allow setuid-mount squashfs",
 			directiveValue: "yes",
-			exit:           0,
+			exit:           1,
 		},
 		{
 			name:           "AllowSetuidMountSquashfsYesBind",
-			argv:           []string{"-B", c.squashfsImage + ":/sqsh:image-src=/", c.sifImage, "true"},
+			argv:           []string{"-B", c.squashfsImage + ":/sqsh:image-src=/", c.sifImage, "sh", "-c", findsquash},
 			profile:        e2e.UserProfile,
 			directive:      "allow setuid-mount squashfs",
 			directiveValue: "yes",
-			exit:           0,
+			exit:           1,
 		},
 		{
 			name:           "AllowSetuidMountExtfsNo",

examples/plugins/ubuntu-userns-overlay-plugin/main.go

@@ -13,6 +13,7 @@ import (
 	"fmt"
 	"os/exec"
 	"strings"
+	"syscall"
 
 	"github.com/apptainer/apptainer/pkg/image"
 	pluginapi "github.com/apptainer/apptainer/pkg/plugin"
@@ -70,6 +71,10 @@ func (d *ubuntuOvlDriver) Stop(target string) error {
 	return nil
 }
 
+func (d *ubuntuOvlDriver) Stopped(int, syscall.WaitStatus) error {
+	return nil
+}
+
 // setConfiguration sets "image driver" and "enable overlay" configuration directives
 // during apptainer plugin install step.
 func setConfiguration(_ string) error {