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

AUTHOR¶

Brendan Gregg

SEE ALSO¶

capabilities(7)