way better apparmor docs

Signed-off-by: Jessica Frazelle <acidburn@docker.com>

docs/security/apparmor.md

@@ -16,10 +16,15 @@ operating system and its applications from security threats. To use it, a system
 administrator associates an AppArmor security profile with each program. Docker
 expects to find an AppArmor policy loaded and enforced.
 
-Docker automatically loads container profiles. A profile for the Docker Engine
-itself also exists and is installed with the official *.deb* packages in
-`/etc/apparmor.d/docker` file.
+Docker automatically loads container profiles. The Docker binary installs
+a `docker-default` profile in the `/etc/apparmor.d/docker` file. This profile
+is used on containers, _not_ on the Docker Daemon.
 
+A profile for the Docker Engine Daemon exists but it is not currently installed 
+with the deb packages. If you are interested in the source for the Daemon
+profile, it is located in
+[contrib/apparmor](https://github.com/docker/docker/tree/master/contrib/apparmor)
+in the Docker Engine source repository.
 
 ## Understand the policies
 
@@ -67,9 +72,112 @@ explicitly specifies the default policy:
 $ docker run --rm -it --security-opt apparmor:docker-default hello-world
 ```
 
+## Loading and Unloading Profiles
+
+To load a new profile into AppArmor, for use with containers:
+
+```
+$ apparmor_parser -r -W /path/to/your_profile
+```
+
+Then you can run the custom profile with `--security-opt` like so:
+
+```bash
+$ docker run --rm -it --security-opt apparmor:your_profile hello-world
+```
+
+To unload a profile from AppArmor:
+
+```bash
+# stop apparmor
+$ /etc/init.d/apparmor stop
+# unload the profile
+$ apparmor_parser -R /path/to/profile
+# start apparmor
+$ /etc/init.d/apparmor start
+```
+
+## Debugging AppArmor
+
+### Using `dmesg`
+
+Here are some helpful tips for debugging any problems you might be facing with
+regard to AppArmor.
+
+AppArmor sends quite verbose messaging to `dmesg`. Usually an AppArmor line
+will look like the following:
+
+```
+[ 5442.864673] audit: type=1400 audit(1453830992.845:37): apparmor="ALLOWED" operation="open" profile="/usr/bin/docker" name="/home/jessie/docker/man/man1/docker-attach.1" pid=10923 comm="docker" requested_mask="r" denied_mask="r" fsuid=1000 ouid=0
+```
+
+In the above example, the you can see `profile=/usr/bin/docker`. This means the
+user has the `docker-engine` (Docker Engine Daemon) profile loaded.
+
+> **Note:** On version of Ubuntu > 14.04 this is all fine and well, but Trusty
+> users might run into some issues when trying to `docker exec`.
+
+Let's look at another log line:
+
+```
+[ 3256.689120] type=1400 audit(1405454041.341:73): apparmor="DENIED" operation="ptrace" profile="docker-default" pid=17651 comm="docker" requested_mask="receive" denied_mask="receive"
+```
+
+This time the profile is `docker-default`, which is run on containers by
+default unless in `privileged` mode. It is telling us, that apparmor has denied
+`ptrace` in the container. This is great.
+
+### Using `aa-status`
+
+If you need to check which profiles are loaded you can use `aa-status`. The
+output looks like:
+
+```bash
+$ sudo aa-status
+apparmor module is loaded.
+14 profiles are loaded.
+1 profiles are in enforce mode.
+   docker-default
+13 profiles are in complain mode.
+   /usr/bin/docker
+   /usr/bin/docker///bin/cat
+   /usr/bin/docker///bin/ps
+   /usr/bin/docker///sbin/apparmor_parser
+   /usr/bin/docker///sbin/auplink
+   /usr/bin/docker///sbin/blkid
+   /usr/bin/docker///sbin/iptables
+   /usr/bin/docker///sbin/mke2fs
+   /usr/bin/docker///sbin/modprobe
+   /usr/bin/docker///sbin/tune2fs
+   /usr/bin/docker///sbin/xtables-multi
+   /usr/bin/docker///sbin/zfs
+   /usr/bin/docker///usr/bin/xz
+38 processes have profiles defined.
+37 processes are in enforce mode.
+   docker-default (6044)
+   ...
+   docker-default (31899)
+1 processes are in complain mode.
+   /usr/bin/docker (29756)
+0 processes are unconfined but have a profile defined.
+```
+
+In the above output you can tell that the `docker-default` profile running on
+various container PIDs is in `enforce` mode. This means AppArmor will actively
+block and audit in `dmesg` anything outside the bounds of the `docker-default`
+profile.
+
+The output above also shows the `/usr/bin/docker` (Docker Engine Daemon)
+profile is running in `complain` mode. This means AppArmor will _only_ log to
+`dmesg` activity outside the bounds of the profile. (Except in the case of
+Ubuntu Trusty, where we have seen some interesting behaviors being enforced.)
+
 ## Contributing to AppArmor code in Docker
 
 Advanced users and package managers can find a profile for `/usr/bin/docker`
-underneath
+(Docker Engine Daemon) underneath
 [contrib/apparmor](https://github.com/docker/docker/tree/master/contrib/apparmor)
 in the Docker Engine source repository.
+
+The `docker-default` profile for containers lives in
+[profiles/apparmor](https://github.com/docker/docker/tree/master/profiles/apparmor).