runc: fix CVE-2019-16884

Signed-off-by: Chen Qi <Qi.Chen@windriver.com>
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>

3 files changed, 203 insertions, 0 deletions

diff --git a/recipes-containers/runc/files/0001-Only-allow-proc-mount-if-it-is-procfs.patch b/recipes-containers/runc/files/0001-Only-allow-proc-mount-if-it-is-procfs.patch
new file mode 100644
index 00000000..5aca99e2
--- /dev/null
+++ b/recipes-containers/runc/files/0001-Only-allow-proc-mount-if-it-is-procfs.patch
@@ -0,0 +1,201 @@
+From d75b05441772417a0828465a9483f16287937724 Mon Sep 17 00:00:00 2001
+From: Michael Crosby <crosbymichael@gmail.com>
+Date: Mon, 23 Sep 2019 16:45:45 -0400
+Subject: [PATCH] Only allow proc mount if it is procfs
+
+Fixes #2128
+
+This allows proc to be bind mounted for host and rootless namespace usecases but
+it removes the ability to mount over the top of proc with a directory.
+
+```bash
+> sudo docker run --rm  apparmor
+docker: Error response from daemon: OCI runtime create failed:
+container_linux.go:346: starting container process caused "process_linux.go:449:
+container init caused \"rootfs_linux.go:58: mounting
+\\\"/var/lib/docker/volumes/aae28ea068c33d60e64d1a75916cf3ec2dc3634f97571854c9ed30c8401460c1/_data\\\"
+to rootfs
+\\\"/var/lib/docker/overlay2/a6be5ae911bf19f8eecb23a295dec85be9a8ee8da66e9fb55b47c841d1e381b7/merged\\\"
+at \\\"/proc\\\" caused
+\\\"\\\\\\\"/var/lib/docker/overlay2/a6be5ae911bf19f8eecb23a295dec85be9a8ee8da66e9fb55b47c841d1e381b7/merged/proc\\\\\\\"
+cannot be mounted because it is not of type proc\\\"\"": unknown.
+
+> sudo docker run --rm -v /proc:/proc apparmor
+
+docker-default (enforce)        root     18989  0.9  0.0   1288     4 ?
+Ss   16:47   0:00 sleep 20
+```
+
+Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
+
+Upstream-Status: Backport [https://github.com/opencontainers/runc/pull/2129/commits/331692baa7afdf6c186f8667cb0e6362ea0802b3]
+
+CVE: CVE-2019-16884
+
+Signed-off-by: Chen Qi <Qi.Chen@windriver.com>
+---
+ libcontainer/container_linux.go   |  4 +--
+ libcontainer/rootfs_linux.go      | 50 +++++++++++++++++++++++--------
+ libcontainer/rootfs_linux_test.go |  8 ++---
+ 3 files changed, 43 insertions(+), 19 deletions(-)
+
+diff --git a/libcontainer/container_linux.go b/libcontainer/container_linux.go
+index 7e58e5e0..d51e35df 100644
+--- a/src/import/libcontainer/container_linux.go
++++ b/src/import/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 f13b226e..5650b0ac 100644
+--- a/src/import/libcontainer/rootfs_linux.go
++++ b/src/import/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 d755984b..1bfe7c66 100644
+--- a/src/import/libcontainer/rootfs_linux_test.go
++++ b/src/import/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)
+        }
+-- 
+2.17.1
+
diff --git a/recipes-containers/runc/runc-docker_git.bb b/recipes-containers/runc/runc-docker_git.bb
index c9f460b2..8d810d01 100644
--- a/recipes-containers/runc/runc-docker_git.bb
+++ b/recipes-containers/runc/runc-docker_git.bb
@@ -7,6 +7,7 @@ SRC_URI = "git://github.com/opencontainers/runc;nobranch=1;name=runc-docker \
            file://0001-runc-Add-console-socket-dev-null.patch \
            file://0001-Makefile-respect-GOBUILDFLAGS-for-runc-and-remove-re.patch \
            file://0001-runc-docker-SIGUSR1-daemonize.patch \
+           file://0001-Only-allow-proc-mount-if-it-is-procfs.patch \
           "
 
 RUNC_VERSION = "1.0.0-rc8"
diff --git a/recipes-containers/runc/runc-opencontainers_git.bb b/recipes-containers/runc/runc-opencontainers_git.bb
index 361bc94b..3a7e7aaf 100644
--- a/recipes-containers/runc/runc-opencontainers_git.bb
+++ b/recipes-containers/runc/runc-opencontainers_git.bb
@@ -4,5 +4,6 @@ SRCREV = "652297c7c7e6c94e8d064ad5916c32891a6fd388"
 SRC_URI = " \
     git://github.com/opencontainers/runc;branch=master \
     file://0001-Makefile-respect-GOBUILDFLAGS-for-runc-and-remove-re.patch \
+    file://0001-Only-allow-proc-mount-if-it-is-procfs.patch \
     "
 RUNC_VERSION = "1.0.0-rc8"