Provided by: apparmor_2.7.102-0ubuntu3_i386 bug


       AppArmor - kernel enhancement to confine programs to a limited set of


       AppArmor is a kernel enhancement to confine programs to a limited set
       of resources. AppArmor's unique security model is to bind access
       control attributes to programs rather than to users.

       AppArmor confinement is provided via profiles loaded into the kernel
       via apparmor_parser(8), typically through the /etc/init.d/apparmor SysV
       initscript (on Ubuntu, also see UBUNTU POLICY LOAD, below), which is
       used like this:

               # /etc/init.d/apparmor start
               # /etc/init.d/apparmor stop
               # /etc/init.d/apparmor restart

       AppArmor can operate in two modes: enforcement, and complain or

       ·   enforcement -  Profiles loaded in enforcement mode will result in
           enforcement of the policy defined in the profile as well as
           reporting policy violation attempts to syslogd.

       ·   complain - Profiles loaded in  "complain" mode will not enforce
           policy.  Instead, it will report policy violation attempts. This
           mode is convenient for developing profiles. To manage complain mode
           for individual profiles the utilities aa-complain(8) and
           aa-enforce(8) can be used.  These utilities take a program name as
           an argument.

       Profiles are traditionally stored in files in /etc/apparmor.d/ under
       filenames with the convention of replacing the / in pathnames with .
       (except for the root /) so profiles are easier to manage (e.g. the
       /usr/sbin/nscd profile would be named usr.sbin.nscd).

       Profiles are applied to a process at exec(3) time (as seen through the
       execve(2) system call); an already running process cannot be confined.
       However, once a profile is loaded for a program, that program will be
       confined on the next exec(3).

       AppArmor supports the Linux kernel's securityfs filesystem, and makes
       available the list of the profiles currently loaded; to mount the

               # mount -tsecurityfs securityfs /sys/kernel/security
               $ cat /sys/kernel/security/apparmor/profiles

       Normally, the initscript will mount securityfs if it has not already
       been done.

       AppArmor also restricts what privileged operations a confined process
       may execute, even if the process is running as root. A confined process
       cannot call the following system calls:

               create_module(2) delete_module(2) init_module(2) ioperm(2)
               iopl(2) mount(2) umount(2) ptrace(2) reboot(2) setdomainname(2)
               sethostname(2) swapoff(2) swapon(2) sysctl(2)

       A confined process can not call mknod(2) to create character or block


       Ubuntu systems use Upstart instead of a traditional SysV init system.
       Because Upstart is an event-driven init system and understanding that
       policy must be loaded before execution, Ubuntu loads policy in two
       stages: first via upstart jobs for binaries that are started in early
       boot, and then via a SysV initscript that starts in S37 for all
       remaining policy. When developing policy it is important to know how
       your application is started and if policy load should be handled

       In general, nothing extra has to be done for applications without an
       initscript or with an initscript that starts after AppArmor's second
       stage initscript.

       If the confined application has an Upstart job, adjust the job to call
       /lib/init/apparmor-profile-load with the filename of the policy file
       (relative to /etc/apparmor.d/). For example:

               pre-start script
               end script

       If the confined application does not have an Upstart job but it starts
       before AppArmor's second stage initscript, then add a symlink from the
       policy file in /etc/apparmor.d to
       /etc/apparmor/init/network-interface-security/. For example:

               # cd /etc/apparmor/init/network-interface-security/
               # ln -s /etc/apparmor.d/ .

       The network-interface-security Upstart job will load all the symlinked
       policy files in /etc/apparmor/init/network-interface-security/ before
       any network interfaces come up. Because network interfaces come up very
       early in the boot process, this will help ensure that AppArmor policy
       is loaded before the confined application starts.


       When a confined process tries to access a file it does not have
       permission to access, the kernel will report a message through audit,
       similar to:

               audit(1148420912.879:96): REJECTING x access to /bin/uname
                 (sh(6646) profile /tmp/sh active /tmp/sh)

               audit(1148420912.879:97): REJECTING r access to /bin/uname
                 (sh(6646) profile /tmp/sh active /tmp/sh)

               audit(1148420944.837:98): REJECTING access to capability
                 'dac_override' (sh(6641) profile /tmp/sh active /tmp/sh)

       The permissions requested by the process are immediately after
       REJECTING. The "name" and process id of the running program are
       reported, as well as the profile name and any "hat" that may be active.
       ("Name" is in quotes, because the process name is limited to 15 bytes;
       it is the same as reported through the Berkeley process accounting.) If
       no hat is active (see aa_change_hat(2)) then the profile name is
       printed for "active".

       For confined processes running under a profile that has been loaded in
       complain mode, enforcement will not take place and the log messages
       reported to audit will be of the form:

               audit(1146868287.904:237): PERMITTING r access to
                 /etc/apparmor.d/tunables (du(3811) profile /usr/bin/du active

               audit(1146868287.904:238): PERMITTING r access to /etc/apparmor.d
                 (du(3811) profile /usr/bin/du active /usr/bin/du)

       If the userland auditd is not running, the kernel will send audit
       events to klogd; klogd will send the messages to syslog, which will log
       the messages with the KERN facility. Thus, REJECTING and PERMITTING
       messages may go to either /var/log/audit/audit.log or
       /var/log/messages, depending upon local configuration.




       apparmor_parser(8), aa_change_hat(2), apparmor.d(5), subdomain.conf(5),
       aa-autodep(1), clean(1), auditd(8), aa-unconfined(8), aa-enforce(1),
       aa-complain(1), and <>.