capable

NAME

capable - Trace security capability checks (cap_capable()).

SYNOPSIS

capable [-h] [-v] [-p PID] [-K] [-U] [-x] [--cgroupmap MAPPATH]
[--mntnsmap MAPPATH] [--unique]

DESCRIPTION

This traces security capability checks in the kernel, and prints details for each call. This can be useful for general debugging, and also security enforcement: determining a white list of capabilities an application needs.

Since this uses BPF, only the root user can use this tool.

REQUIREMENTS

CONFIG_BPF, bcc.

OPTIONS

-h USAGE message.

	-v		Include non-audit capability checks. These are those deemed not interesting and not necessary to audit, such as CAP_SYS_ADMIN checks on memory allocation to affect the behavior of overcommit.
	-K		Include kernel stack traces to the output.
	-U		Include user-space stack traces to the output.
	-x		Show extra fields in TID and INSETID columns.

--cgroupmap MAPPATH

Trace cgroups in this BPF map only (filtered in-kernel).

--mntnsmap MAPPATH

Trace mount namespaces in this BPF map only (filtered in-kernel).

--unique

Don’t repeat stacks for the same PID or cgroup.

EXAMPLES

Trace all capability checks system-wide:

# capable

Trace capability checks for PID 181:

# capable -p 181

Trace capability checks in a set of cgroups only (see special_filtering.md

from bcc sources for more details): # capable --cgroupmap /sys/fs/bpf/test01

FIELDS

TIME(s)

Time of capability check: HH:MM:SS.

	UID		User ID.
	PID		Process ID.
	COMM		Process name. CAP Capability number. NAME Capability name. See capabilities(7) for descriptions.
	AUDIT		Whether this was an audit event. Use -v to include non-audit events. INSETID Whether the INSETID bit was set (Linux >= 5.1).

OVERHEAD

This adds low-overhead instrumentation to capability checks, which are expected to be low frequency, however, that depends on the application. Test in a lab environment before use.

SOURCE

This is from bcc.

https://github.com/iovisor/bcc

Also look in the bcc distribution for a companion _examples.txt file containing example usage, output, and commentary for this tool.

OS

Linux

STABILITY

Unstable - in development.

AUTHOR

Brendan Gregg

SEE ALSO

capabilities(7)