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=== Description (from pull-request) ===
Note that this only allows privileged containers to load apparmor profiles, and
only then with something like:
diff --git a/config/apparmor/abstractions/container-base b/config/apparmor/abstractions/container-base
index fe24ff3..7138249 100644
--- a/config/apparmor/abstractions/container-base
+++ b/config/apparmor/abstractions/container-base
@@ -93,7 +93,7 @@
mount fstype=sysfs -> /sys/,
mount options=(rw, nosuid, nodev, noexec, remount) -> /sys/,
deny /sys/firmware/efi/efivars/** rwklx,
- deny /sys/kernel/security/** rwklx,
+ # deny /sys/kernel/security/** rwklx,
mount options=(move) /sys/fs/cgroup/cgmanager/ -> /sys/fs/cgroup/cgmanager.lower/,
mount options=(ro, nosuid, nodev, noexec, remount, strictatime) -> /sys/fs/cgroup/,
We'll need to do something with the permissions on
/sys/kernel/security/apparmor to allow unprivileged users to write to it. I'll
be in touch with the security team about that, but for now I don't think this
hurts anything.
Signed-off-by: Tycho Andersen <tycho.ander...@canonical.com>
From 2f93569e660ded55d554a4a4e6a8065d94835b42 Mon Sep 17 00:00:00 2001
From: Tycho Andersen <tycho.ander...@canonical.com>
Date: Fri, 17 Jun 2016 17:51:17 +0000
Subject: [PATCH] apparmor: create an apparmor namespace for each container
Note that this only allows privileged containers to load apparmor profiles, and
only then with something like:
diff --git a/config/apparmor/abstractions/container-base
b/config/apparmor/abstractions/container-base
index fe24ff3..7138249 100644
--- a/config/apparmor/abstractions/container-base
+++ b/config/apparmor/abstractions/container-base
@@ -93,7 +93,7 @@
mount fstype=sysfs -> /sys/,
mount options=(rw, nosuid, nodev, noexec, remount) -> /sys/,
deny /sys/firmware/efi/efivars/** rwklx,
- deny /sys/kernel/security/** rwklx,
+ # deny /sys/kernel/security/** rwklx,
mount options=(move) /sys/fs/cgroup/cgmanager/ ->
/sys/fs/cgroup/cgmanager.lower/,
mount options=(ro, nosuid, nodev, noexec, remount, strictatime) ->
/sys/fs/cgroup/,
We'll need to do something with the permissions on
/sys/kernel/security/apparmor to allow unprivileged users to write to it. I'll
be in touch with the security team about that, but for now I don't think this
hurts anything.
Signed-off-by: Tycho Andersen <tycho.ander...@canonical.com>
---
lxd/apparmor.go | 87 ++++++++++++++++++++++++++++++++++++++++++++--------
lxd/container_lxc.go | 25 +++++++++++++--
lxd/daemon.go | 11 +++++++
test/suites/basic.sh | 5 +--
4 files changed, 111 insertions(+), 17 deletions(-)
diff --git a/lxd/apparmor.go b/lxd/apparmor.go
index ce25c50..c2c2327 100644
--- a/lxd/apparmor.go
+++ b/lxd/apparmor.go
@@ -47,6 +47,22 @@ const NESTING_AA_PROFILE = `
signal,
`
+const DEFAULT_AA_NAMESPACE_PROFILE = `
+#include <tunables/global>
+profile "lxd-default" flags=(attach_disconnected,mediate_deleted) {
+ #include <abstractions/lxc/container-base>
+
+ # Special exception for cgroup namespaces
+ %s
+
+ # user input raw.apparmor below here
+ %s
+
+ # nesting support goes here if needed
+ %s
+ change_profile -> ":%s://*",
+}`
+
const DEFAULT_AA_PROFILE = `
#include <tunables/global>
profile "%s" flags=(attach_disconnected,mediate_deleted) {
@@ -63,17 +79,35 @@ profile "%s" flags=(attach_disconnected,mediate_deleted) {
change_profile -> "%s",
}`
-func AAProfileFull(c container) string {
- lxddir := shared.VarPath("")
- if len(c.Name())+len(lxddir)+7 >= 253 {
+func mkApparmorName(name string) string {
+ if len(name)+7 >= 253 {
hash := sha256.New()
- io.WriteString(hash, lxddir)
- lxddir = fmt.Sprintf("%x", hash.Sum(nil))
+ io.WriteString(hash, name)
+ return fmt.Sprintf("%x", hash.Sum(nil))
}
+ return name
+}
+
+func AANamespace(c container) string {
+ /* / is not allowed in apparmor namespace names; let's also trim the
+ * leading / so it doesn't look like "-var-lib-lxd"
+ */
+ lxddir := strings.Replace(shared.VarPath("")[1:], "/", "-", -1)
+ lxddir = mkApparmorName(lxddir)
return fmt.Sprintf("lxd-%s_<%s>", c.Name(), lxddir)
}
+func AAProfileFull(c container) string {
+ if aaStacking {
+ return fmt.Sprintf(":%s://lxd-default", AANamespace(c))
+ } else {
+ lxddir := shared.VarPath("")
+ lxddir = mkApparmorName(lxddir)
+ return fmt.Sprintf("lxd-%s_<%s>", c.Name(), lxddir)
+ }
+}
+
func AAProfileShort(c container) string {
return fmt.Sprintf("lxd-%s", c.Name())
}
@@ -99,7 +133,26 @@ func getAAProfileContent(c container) string {
nesting = NESTING_AA_PROFILE
}
- return fmt.Sprintf(DEFAULT_AA_PROFILE, AAProfileFull(c),
AAProfileCgns(), rawApparmor, nesting, AAProfileFull(c))
+ if aaStacking {
+ return fmt.Sprintf(
+ DEFAULT_AA_NAMESPACE_PROFILE,
+ AAProfileCgns(),
+ rawApparmor,
+ nesting,
+ AANamespace(c),
+ )
+ } else {
+ full := AAProfileFull(c)
+
+ return fmt.Sprintf(
+ DEFAULT_AA_PROFILE,
+ full,
+ AAProfileCgns(),
+ rawApparmor,
+ nesting,
+ full,
+ )
+ }
}
func runApparmor(command string, c container) error {
@@ -107,12 +160,17 @@ func runApparmor(command string, c container) error {
return nil
}
- cmd := exec.Command("apparmor_parser", []string{
+ args := []string{
fmt.Sprintf("-%sWL", command),
path.Join(aaPath, "cache"),
path.Join(aaPath, "profiles", AAProfileShort(c)),
- }...)
+ }
+ if aaStacking {
+ args = append([]string{"-n", AANamespace(c)}, args...)
+ }
+
+ cmd := exec.Command("apparmor_parser", args...)
output, err := cmd.CombinedOutput()
if err != nil {
shared.Log.Error("Running apparmor",
@@ -165,14 +223,19 @@ func AALoadProfile(c container) error {
return runApparmor(APPARMOR_CMD_LOAD, c)
}
-// Ensure that the container's policy is unloaded to free kernel memory. This
-// does not delete the policy from disk or cache.
-func AAUnloadProfile(c container) error {
+// Ensure that the container's policy namespace is unloaded to free kernel
+// memory. This does not delete the policy from disk or cache.
+func AADestroy(c container) error {
if !aaAdmin {
return nil
}
- return runApparmor(APPARMOR_CMD_UNLOAD, c)
+ if aaStacking {
+ content := []byte(fmt.Sprintf(":%s:", AANamespace(c)))
+ return
ioutil.WriteFile("/sys/kernel/security/apparmor/.remove", content, 0)
+ } else {
+ return runApparmor(APPARMOR_CMD_UNLOAD, c)
+ }
}
// Parse the profile without loading it into the kernel.
diff --git a/lxd/container_lxc.go b/lxd/container_lxc.go
index 6fd0ee4..427e17c 100644
--- a/lxd/container_lxc.go
+++ b/lxd/container_lxc.go
@@ -293,7 +293,12 @@ func (c *containerLXC) initLXC() error {
}
// Base config
- err = lxcSetConfigItem(cc, "lxc.cap.drop", "mac_admin mac_override
sys_time sys_module sys_rawio")
+ toDrop := "sys_time sys_module sys_rawio"
+ if !aaStacking || c.IsPrivileged() {
+ toDrop = toDrop + " mac_admin mac_override"
+ }
+
+ err = lxcSetConfigItem(cc, "lxc.cap.drop", toDrop)
if err != nil {
return err
}
@@ -490,7 +495,19 @@ func (c *containerLXC) initLXC() error {
}
} else {
// If not currently confined, use the container's
profile
- err := lxcSetConfigItem(cc, "lxc.aa_profile",
AAProfileFull(c))
+ profile := AAProfileFull(c)
+
+ /* In the unprivileged case, we're relying on the user
+ * namespace to do all the access control. We can thus
+ * just move the container into a namespace and leave
+ * it unconfined, so it can load its own profiles if it
+ * wants to.
+ */
+ if aaStacking && !c.IsPrivileged() {
+ profile = fmt.Sprintf(":%s:", AANamespace(c))
+ }
+
+ err := lxcSetConfigItem(cc, "lxc.aa_profile", profile)
if err != nil {
return err
}
@@ -1450,7 +1467,9 @@ func (c *containerLXC) OnStop(target string) error {
}
// Unload the apparmor profile
- AAUnloadProfile(c)
+ if err := AADestroy(c); err != nil {
+ shared.Log.Error("failed to destroy apparmor namespace",
log.Ctx{"container": c.Name(), "err": err})
+ }
// FIXME: The go routine can go away once we can rely on LXC_TARGET
go func(c *containerLXC, target string, wg *sync.WaitGroup) {
diff --git a/lxd/daemon.go b/lxd/daemon.go
index 37a2338..8657746 100644
--- a/lxd/daemon.go
+++ b/lxd/daemon.go
@@ -41,6 +41,7 @@ import (
var aaAdmin = true
var aaAvailable = true
var aaConfined = false
+var aaStacking = false
// CGroup
var cgBlkioController = false
@@ -626,6 +627,16 @@ func (d *Daemon) Init() error {
}
}
+ if aaAvailable {
+ content, err :=
ioutil.ReadFile("/sys/kernel/security/apparmor/features/domain/stack")
+ if err == nil && string(content) == "yes\n" {
+ aaStacking = true
+ shared.Log.Warn("Enabled apparmor stacking")
+ } else {
+ shared.Log.Warn("Kernel doesn't support apparmor
stacking")
+ }
+ }
+
/* Detect CGroup support */
cgBlkioController = shared.PathExists("/sys/fs/cgroup/blkio/")
if !cgBlkioController {
diff --git a/test/suites/basic.sh b/test/suites/basic.sh
index 7e4f915..0f5f265 100644
--- a/test/suites/basic.sh
+++ b/test/suites/basic.sh
@@ -299,9 +299,10 @@ test_basic_usage() {
# check that an apparmor profile is created for this container, that it is
# unloaded on stop, and that it is deleted when the container is deleted
lxc launch testimage lxd-apparmor-test
- aa-status | grep "lxd-lxd-apparmor-test_<${LXD_DIR}>"
+ aa_namespace="lxd-lxd-apparmor-test_<$(echo "${LXD_DIR}" | sed -e 's/\//-/g'
-e 's/^.//')>"
+ aa-status | grep ":${aa_namespace}://lxd-default"
lxc stop lxd-apparmor-test --force
- ! aa-status | grep -q "lxd-lxd-apparmor-test_<${LXD_DIR}>"
+ ! aa-status | grep -q ":${aa_namespace}://lxd-default"
lxc delete lxd-apparmor-test
[ ! -f "${LXD_DIR}/security/apparmor/profiles/lxd-lxd-apparmor-test" ]
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