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       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, 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

       o   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.

       o   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


       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 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), change_hat(2), apparmor.d(5), subdomain.conf(5),
       autodep(1), clean(1), auditd(8), unconfined(8), enforce(1),
       complain(1), and