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runc/CVE-2019-16884.patch

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From 6ce3791ce27128f8b4ae45323effa10953fa9904 Mon Sep 17 00:00:00 2001
From: Aleksa Sarai <asarai@suse.de>
Date: Mon, 23 Sep 2019 16:45:45 -0400
Subject: [PATCH] CVE-2019-16884
This patch includes a squash of the following upstream patches:
* 331692baa7af ("Only allow proc mount if it is procfs")
As well as the following still-in-review patches:
* ("apparmor: verify that writes to /proc/... are on procfs")
* ("selinux: verify that writes to /proc/... are on procfs")
Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
Signed-off-by: Aleksa Sarai <asarai@suse.de>
---
libcontainer/apparmor/apparmor.go | 18 ++++++-
libcontainer/container_linux.go | 4 +-
libcontainer/rootfs_linux.go | 50 ++++++++++++++-----
libcontainer/rootfs_linux_test.go | 8 +--
.../selinux/go-selinux/selinux_linux.go | 20 ++++++++
5 files changed, 79 insertions(+), 21 deletions(-)
diff --git a/libcontainer/apparmor/apparmor.go b/libcontainer/apparmor/apparmor.go
index 7fff0627fa1b..3504b80d8643 100644
--- a/libcontainer/apparmor/apparmor.go
+++ b/libcontainer/apparmor/apparmor.go
@@ -6,6 +6,8 @@ import (
"fmt"
"io/ioutil"
"os"
+
+ "golang.org/x/sys/unix"
)
// IsEnabled returns true if apparmor is enabled for the host.
@@ -19,7 +21,13 @@ func IsEnabled() bool {
return false
}
-func setprocattr(attr, value string) error {
+func isProcHandle(fh *os.File) (bool, error) {
+ var buf unix.Statfs_t
+ err := unix.Fstatfs(int(fh.Fd()), &buf)
+ return buf.Type == unix.PROC_SUPER_MAGIC, err
+}
+
+func setProcAttr(attr, value string) error {
// Under AppArmor you can only change your own attr, so use /proc/self/
// instead of /proc/<tid>/ like libapparmor does
path := fmt.Sprintf("/proc/self/attr/%s", attr)
@@ -30,6 +38,12 @@ func setprocattr(attr, value string) error {
}
defer f.Close()
+ if ok, err := isProcHandle(f); err != nil {
+ return err
+ } else if !ok {
+ return fmt.Errorf("/proc path not on procfs: %s", path)
+ }
+
_, err = fmt.Fprintf(f, "%s", value)
return err
}
@@ -37,7 +51,7 @@ func setprocattr(attr, value string) error {
// changeOnExec reimplements aa_change_onexec from libapparmor in Go
func changeOnExec(name string) error {
value := "exec " + name
- if err := setprocattr("exec", value); err != nil {
+ if err := setProcAttr("exec", value); err != nil {
return fmt.Errorf("apparmor failed to apply profile: %s", err)
}
return nil
diff --git a/libcontainer/container_linux.go b/libcontainer/container_linux.go
index 7e58e5e00824..d51e35dffb93 100644
--- a/libcontainer/container_linux.go
+++ b/libcontainer/container_linux.go
@@ -19,7 +19,7 @@ import (
"syscall" // only for SysProcAttr and Signal
"time"
- "github.com/cyphar/filepath-securejoin"
+ securejoin "github.com/cyphar/filepath-securejoin"
"github.com/opencontainers/runc/libcontainer/cgroups"
"github.com/opencontainers/runc/libcontainer/configs"
"github.com/opencontainers/runc/libcontainer/intelrdt"
@@ -1160,7 +1160,7 @@ func (c *linuxContainer) makeCriuRestoreMountpoints(m *configs.Mount) error {
if err != nil {
return err
}
- if err := checkMountDestination(c.config.Rootfs, dest); err != nil {
+ if err := checkProcMount(c.config.Rootfs, dest, ""); err != nil {
return err
}
m.Destination = dest
diff --git a/libcontainer/rootfs_linux.go b/libcontainer/rootfs_linux.go
index f13b226e444e..5650b0acbca8 100644
--- a/libcontainer/rootfs_linux.go
+++ b/libcontainer/rootfs_linux.go
@@ -13,7 +13,7 @@ import (
"strings"
"time"
- "github.com/cyphar/filepath-securejoin"
+ securejoin "github.com/cyphar/filepath-securejoin"
"github.com/mrunalp/fileutils"
"github.com/opencontainers/runc/libcontainer/cgroups"
"github.com/opencontainers/runc/libcontainer/configs"
@@ -197,7 +197,7 @@ func prepareBindMount(m *configs.Mount, rootfs string) error {
if dest, err = securejoin.SecureJoin(rootfs, m.Destination); err != nil {
return err
}
- if err := checkMountDestination(rootfs, dest); err != nil {
+ if err := checkProcMount(rootfs, dest, m.Source); err != nil {
return err
}
// update the mount with the correct dest after symlinks are resolved.
@@ -388,7 +388,7 @@ func mountToRootfs(m *configs.Mount, rootfs, mountLabel string, enableCgroupns b
if dest, err = securejoin.SecureJoin(rootfs, m.Destination); err != nil {
return err
}
- if err := checkMountDestination(rootfs, dest); err != nil {
+ if err := checkProcMount(rootfs, dest, m.Source); err != nil {
return err
}
// update the mount with the correct dest after symlinks are resolved.
@@ -435,12 +435,12 @@ func getCgroupMounts(m *configs.Mount) ([]*configs.Mount, error) {
return binds, nil
}
-// checkMountDestination checks to ensure that the mount destination is not over the top of /proc.
+// checkProcMount checks to ensure that the mount destination is not over the top of /proc.
// dest is required to be an abs path and have any symlinks resolved before calling this function.
-func checkMountDestination(rootfs, dest string) error {
- invalidDestinations := []string{
- "/proc",
- }
+//
+// if source is nil, don't stat the filesystem. This is used for restore of a checkpoint.
+func checkProcMount(rootfs, dest, source string) error {
+ const procPath = "/proc"
// White list, it should be sub directories of invalid destinations
validDestinations := []string{
// These entries can be bind mounted by files emulated by fuse,
@@ -463,16 +463,40 @@ func checkMountDestination(rootfs, dest string) error {
return nil
}
}
- for _, invalid := range invalidDestinations {
- path, err := filepath.Rel(filepath.Join(rootfs, invalid), dest)
+ path, err := filepath.Rel(filepath.Join(rootfs, procPath), dest)
+ if err != nil {
+ return err
+ }
+ // pass if the mount path is located outside of /proc
+ if strings.HasPrefix(path, "..") {
+ return nil
+ }
+ if path == "." {
+ // an empty source is pasted on restore
+ if source == "" {
+ return nil
+ }
+ // only allow a mount on-top of proc if it's source is "proc"
+ isproc, err := isProc(source)
if err != nil {
return err
}
- if path != "." && !strings.HasPrefix(path, "..") {
- return fmt.Errorf("%q cannot be mounted because it is located inside %q", dest, invalid)
+ // pass if the mount is happening on top of /proc and the source of
+ // the mount is a proc filesystem
+ if isproc {
+ return nil
}
+ return fmt.Errorf("%q cannot be mounted because it is not of type proc", dest)
}
- return nil
+ return fmt.Errorf("%q cannot be mounted because it is inside /proc", dest)
+}
+
+func isProc(path string) (bool, error) {
+ var s unix.Statfs_t
+ if err := unix.Statfs(path, &s); err != nil {
+ return false, err
+ }
+ return s.Type == unix.PROC_SUPER_MAGIC, nil
}
func setupDevSymlinks(rootfs string) error {
diff --git a/libcontainer/rootfs_linux_test.go b/libcontainer/rootfs_linux_test.go
index d755984bc0f9..1bfe7c663225 100644
--- a/libcontainer/rootfs_linux_test.go
+++ b/libcontainer/rootfs_linux_test.go
@@ -10,7 +10,7 @@ import (
func TestCheckMountDestOnProc(t *testing.T) {
dest := "/rootfs/proc/sys"
- err := checkMountDestination("/rootfs", dest)
+ err := checkProcMount("/rootfs", dest, "")
if err == nil {
t.Fatal("destination inside proc should return an error")
}
@@ -18,7 +18,7 @@ func TestCheckMountDestOnProc(t *testing.T) {
func TestCheckMountDestOnProcChroot(t *testing.T) {
dest := "/rootfs/proc/"
- err := checkMountDestination("/rootfs", dest)
+ err := checkProcMount("/rootfs", dest, "/proc")
if err != nil {
t.Fatal("destination inside proc when using chroot should not return an error")
}
@@ -26,7 +26,7 @@ func TestCheckMountDestOnProcChroot(t *testing.T) {
func TestCheckMountDestInSys(t *testing.T) {
dest := "/rootfs//sys/fs/cgroup"
- err := checkMountDestination("/rootfs", dest)
+ err := checkProcMount("/rootfs", dest, "")
if err != nil {
t.Fatal("destination inside /sys should not return an error")
}
@@ -34,7 +34,7 @@ func TestCheckMountDestInSys(t *testing.T) {
func TestCheckMountDestFalsePositive(t *testing.T) {
dest := "/rootfs/sysfiles/fs/cgroup"
- err := checkMountDestination("/rootfs", dest)
+ err := checkProcMount("/rootfs", dest, "")
if err != nil {
t.Fatal(err)
}
diff --git a/vendor/github.com/opencontainers/selinux/go-selinux/selinux_linux.go b/vendor/github.com/opencontainers/selinux/go-selinux/selinux_linux.go
index d7786c33c197..611df8f9b3b0 100644
--- a/vendor/github.com/opencontainers/selinux/go-selinux/selinux_linux.go
+++ b/vendor/github.com/opencontainers/selinux/go-selinux/selinux_linux.go
@@ -18,6 +18,8 @@ import (
"strings"
"sync"
"syscall"
+
+ "golang.org/x/sys/unix"
)
const (
@@ -252,6 +254,12 @@ func getSELinuxPolicyRoot() string {
return filepath.Join(selinuxDir, readConfig(selinuxTypeTag))
}
+func isProcHandle(fh *os.File) (bool, error) {
+ var buf unix.Statfs_t
+ err := unix.Fstatfs(int(fh.Fd()), &buf)
+ return buf.Type == unix.PROC_SUPER_MAGIC, err
+}
+
func readCon(fpath string) (string, error) {
if fpath == "" {
return "", ErrEmptyPath
@@ -263,6 +271,12 @@ func readCon(fpath string) (string, error) {
}
defer in.Close()
+ if ok, err := isProcHandle(in); err != nil {
+ return "", err
+ } else if !ok {
+ return "", fmt.Errorf("/proc path not on procfs: %s", fpath)
+ }
+
var retval string
if _, err := fmt.Fscanf(in, "%s", &retval); err != nil {
return "", err
@@ -345,6 +359,12 @@ func writeCon(fpath string, val string) error {
}
defer out.Close()
+ if ok, err := isProcHandle(out); err != nil {
+ return err
+ } else if !ok {
+ return fmt.Errorf("/proc path not on procfs: %s", fpath)
+ }
+
if val != "" {
_, err = out.Write([]byte(val))
} else {
--
2.23.0
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