This value can be used to query and set the core dump mode for setuid or otherwise protected/tainted binaries. The modes are
= ========== ===============================================================
0 (default) Traditional behaviour. Any process which has changed
privilege levels or is execute only will not be dumped.
1 (debug) All processes dump core when possible. The core dump is
owned by the current user and no security is applied. This is
intended for system debugging situations only.
Ptrace is unchecked.
This is insecure as it allows regular users to examine the
memory contents of privileged processes.
2 (suidsafe) Any binary which normally would not be dumped is dumped
anyway, but only if the ``core_pattern`` kernel sysctl (see
:ref:`Documentation/admin-guide/sysctl/kernel.rst <core_pattern>`)
is set to
either a pipe handler or a fully qualified path. (For more
details on this limitation, see CVE-2006-2451.) This mode is
appropriate when administrators are attempting to debug
problems in a normal environment, and either have a core dump
pipe handler that knows to treat privileged core dumps with
care, or specific directory defined for catching core dumps.
If a core dump happens without a pipe handler or fully
qualified path, a message will be emitted to syslog warning
about the lack of a correct setting.
= ========== ===============================================================
Documentation for the files in /proc/sys/fs/binfmt_misc is in Documentation/admin-guide/binfmt-misc.rst.
The “mqueue” filesystem provides the necessary kernel features to enable the creation of a user space library that implements the POSIX message queues API (as noted by the MSG tag in the POSIX 1003.1-2001 version of the System Interfaces specification.)
The “mqueue” filesystem contains values for determining/setting the amount of resources used by the file system.
/proc/sys/fs/mqueue/queues_max is a read/write file for setting/getting the maximum number of message queues allowed on the system.
/proc/sys/fs/mqueue/msg_max is a read/write file for setting/getting the maximum number of messages in a queue value. In fact it is the limiting value for another (user) limit which is set in mq_open invocation. This attribute of a queue must be less than or equal to msg_max.
/proc/sys/fs/mqueue/msgsize_max is a read/write file for setting/getting the maximum message size value (it is an attribute of every message queue, set during its creation).
/proc/sys/fs/mqueue/msg_default is a read/write file for setting/getting the default number of messages in a queue value if the attr parameter of mq_open(2) is NULL. If it exceeds msg_max, the default value is initialized to msg_max.
/proc/sys/fs/mqueue/msgsize_default is a read/write file for setting/getting the default message size value if the attr parameter of mq_open(2) is NULL. If it exceeds msgsize_max, the default value is initialized to msgsize_max.
This directory contains configuration options for the epoll(7) interface.