Section 8 · System administration

bcc-capable.8

Package: bcc-tools

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capable

NAME
SYNOPSIS
DESCRIPTION
REQUIREMENTS
OPTIONS
EXAMPLES
FIELDS
OVERHEAD
SOURCE
OS
STABILITY
AUTHOR
SEE ALSO

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