# APPARMOR - man - [phpMan] - To activate a profile:: `sudo aa-enforce usr.bin.firefox` - or: `export _PROFILE_='usr.bin.firefox' sudo $(rm {{path}}$_PROFILE_ ; cat {{path}}$_PROFILE_ | apparmor_parser -a )` - To disable a profile:: `sudo aa-disable usr.bin.firefox` - or: `export _PROFILE_='usr.bin.firefox' sudo $(ln -s {{path}}$_PROFILE_ {{path}} && apparmor_parser -R {{path}}$_PROFILE_)` - To list profiles loaded:: `sudo aa-status` - or: `sudo apparmor_status` - List of available profiles: /etc/apparmor.d/: `` *Source: cheat.sh* --- [_APPARMOR_(7)](https://www.chedong.com/phpMan.php/man/APPARMOR/7/markdown) AppArmor [_APPARMOR_(7)](https://www.chedong.com/phpMan.php/man/APPARMOR/7/markdown) ## NAME AppArmor - kernel enhancement to confine programs to a limited set of resources. ## DESCRIPTION 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)](https://www.chedong.com/phpMan.php/man/apparmorparser/8/markdown), typically through the _apparmor.service_ systemd unit, which is used like this: # systemctl start apparmor # systemctl reload apparmor AppArmor can operate in two modes: _enforcement_, and _complain_ _or_ _learning_: • _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)](https://www.chedong.com/phpMan.php/man/aa-complain/8/markdown) and [**aa-enforce**(8)](https://www.chedong.com/phpMan.php/man/aa-enforce/8/markdown) 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)](https://www.chedong.com/phpMan.php/man/exec/3/markdown) time (as seen through the [**execve**(2)](https://www.chedong.com/phpMan.php/man/execve/2/markdown) system call): once a profile is loaded for a program, that program will be confined on the next [**exec**(3)](https://www.chedong.com/phpMan.php/man/exec/3/markdown). If a process is already running under a profile, when one replaces that profile in the kernel, the updated profile is applied immediately to that process. On the other hand, a process that is already running unconfined cannot be confined. AppArmor supports the Linux kernel's securityfs filesystem, and makes available the list of the profiles currently loaded; to mount the filesystem: # mount -tsecurityfs securityfs /sys/kernel/security $ cat /sys/kernel/security/apparmor/profiles /usr/bin/mutt /usr/bin/gpg ... 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)](https://www.chedong.com/phpMan.php/man/createmodule/2/markdown) [delete_module(2)](https://www.chedong.com/phpMan.php/man/deletemodule/2/markdown) [init_module(2)](https://www.chedong.com/phpMan.php/man/initmodule/2/markdown) [ioperm(2)](https://www.chedong.com/phpMan.php/man/ioperm/2/markdown) [iopl(2)](https://www.chedong.com/phpMan.php/man/iopl/2/markdown) [ptrace(2)](https://www.chedong.com/phpMan.php/man/ptrace/2/markdown) [reboot(2)](https://www.chedong.com/phpMan.php/man/reboot/2/markdown) [setdomainname(2)](https://www.chedong.com/phpMan.php/man/setdomainname/2/markdown) [sethostname(2)](https://www.chedong.com/phpMan.php/man/sethostname/2/markdown) [swapoff(2)](https://www.chedong.com/phpMan.php/man/swapoff/2/markdown) [swapon(2)](https://www.chedong.com/phpMan.php/man/swapon/2/markdown) [sysctl(2)](https://www.chedong.com/phpMan.php/man/sysctl/2/markdown) ### Complain mode Instead of denying access to resources the profile does not have a rule for AppArmor can "allow" the access and log a message for the operation that triggers it. This is called _complain_ _mode_. It is important to note that rules that are present in the profile are still applied, so allow rules will still quiet or force audit messages, and deny rules will still result in denials and quieting of denial messages (see _Turn_ _off_ _deny_ _audit_ _quieting_ if this is a problem). Complain mode can be used to develop profiles incrementally as an application is exercised. The logged accesses can be added to the profile and then can the application further excercised to discover further additions that are needed. Because AppArmor allows the accesses the application will behave as it would if AppArmor was not confining it. **Warning **complain mode does not provide any security, only auditing, while it is enabled. It should not be used in a hostile environment or bad behaviors may be logged and added to the profile as if they are resource accesses that should be used by the application. **Note **complain mode can be very noisy with new or empty profiles, but with developed profiles might not log anything if the profile covers the application behavior well. See _Audit_ _Rate_ _Limiting_ if complain mode is generating too many log messages. To set a profile and any children or hat profiles the profile may contain into complain mode use aa-complain /etc/apparmor.d/ To manually set a specific profile in complain mode, add the "complain" flag, and then manually reload the profile: profile foo flags=(complain) { ... } Note that the "complain" flag must also be added manually to any hats or children profiles of the profile or they will continue to use the previous mode. To enable complain mode globally, run: echo -n complain > /sys/module/apparmor/parameters/mode or to set it on boot add: apparmor.mode=complain as a kernel boot paramenter. **Warning **Setting complain mode gloabally disables all apparmor security protections. It can be useful during debugging or profile development, but setting it selectively on a per profile basis is safer. ## ERRORS 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(1386511672.612:238): apparmor="DENIED" operation="exec" parent=7589 profile="/tmp/sh" name="/bin/uname" pid=7605 comm="sh" requested_mask="x" denied_mask="x" fsuid=0 ouid=0 audit(1386511672.613:239): apparmor="DENIED" operation="open" parent=7589 profile="/tmp/sh" name="/bin/uname" pid=7605 comm="sh" requested_mask="r" denied_mask="r" fsuid=0 ouid=0 audit(1386511772.804:246): apparmor="DENIED" operation="capable" parent=7246 profile="/tmp/sh" pid=7589 comm="sh" pid=7589 comm="sh" capability=2 capname="dac_override" The permissions requested by the process are described in the operation= and denied_mask= (for files - capabilities etc. use a slightly different log format). The "name" and process id of the running program are reported, as well as the profile name including any "hat" that may be active, separated by "//". ("Name" is in quotes, because the process name is limited to 15 bytes; it is the same as reported through the Berkeley process accounting.) 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(1386512577.017:275): apparmor="ALLOWED" operation="open" parent=8012 profile="/usr/bin/du" name="/etc/apparmor.d/tunables/" pid=8049 comm="du" requested_mask="r" denied_mask="r" fsuid=1000 ouid=0 audit(1386512577.017:276): apparmor="ALLOWED" operation="open" parent=8012 profile="/usr/bin/du" name="/etc/apparmor.d/tunables/" pid=8049 comm="du" requested_mask="r" denied_mask="r" fsuid=1000 ouid=0 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. ## DEBUGGING AppArmor provides a few facilities to log more information, which can help debugging profiles. ### Enable debug mode When debug mode is enabled, AppArmor will log a few extra messages to dmesg (not via the audit subsystem). For example, the logs will tell whether environment scrubbing has been applied. To enable debug mode, run: echo 1 > /sys/module/apparmor/parameters/debug or to set it on boot add: apparmor.debug=1 as a kernel boot paramenter. ### Turn off deny audit quieting By default, operations that trigger "deny" rules are not logged. This is called _deny_ _audit_ _quieting_. To turn off deny audit quieting, run: echo -n noquiet >/sys/module/apparmor/parameters/audit or to set it on boot add: apparmor.audit=noquiet as a kernel boot paramenter. ### Force audit mode AppArmor can log a message for every operation that triggers a rule configured in the policy. This is called _force_ _audit_ _mode_. **Warning! **Force audit mode can be extremely noisy even for a single profile, let alone when enabled globally. To set a specific profile in force audit mode, add the "audit" flag: profile foo flags=(audit) { ... } To enable force audit mode globally, run: echo -n all > /sys/module/apparmor/parameters/audit or to set it on boot add: apparmor.audit=all as a kernel boot paramenter. ### Audit Rate Limiting If auditd is not running, to avoid losing too many of the extra log messages, you will likely have to turn off rate limiting by doing: echo 0 > /proc/sys/kernel/printk_ratelimit But even then the kernel ring buffer may overflow and you might lose messages. Else, if auditd is running, see [**auditd**(8)](https://www.chedong.com/phpMan.php/man/auditd/8/markdown) and [**auditd.conf**(5)](https://www.chedong.com/phpMan.php/man/auditd.conf/5/markdown). ## FILES _/etc/apparmor.d/_ _/var/cache/apparmor/_ _/var/log/audit/audit.log_ _/var/log/messages_ ## SEE ALSO [**apparmor_parser**(8)](https://www.chedong.com/phpMan.php/man/apparmorparser/8/markdown), [**aa_change_hat**(2)](https://www.chedong.com/phpMan.php/man/aachangehat/2/markdown), [**apparmor.d**(5)](https://www.chedong.com/phpMan.php/man/apparmor.d/5/markdown), [**aa-autodep**(1)](https://www.chedong.com/phpMan.php/man/aa-autodep/1/markdown), [**clean**(1)](https://www.chedong.com/phpMan.php/man/clean/1/markdown), [**auditd**(8)](https://www.chedong.com/phpMan.php/man/auditd/8/markdown), [**aa-unconfined**(8)](https://www.chedong.com/phpMan.php/man/aa-unconfined/8/markdown), [**aa-enforce**(1)](https://www.chedong.com/phpMan.php/man/aa-enforce/1/markdown), [**aa-complain**(1)](https://www.chedong.com/phpMan.php/man/aa-complain/1/markdown), and <>. AppArmor 4.0.1 2026-04-13 [_APPARMOR_(7)](https://www.chedong.com/phpMan.php/man/APPARMOR/7/markdown)