NAME

veriexec — format for the Veriexec signatures file

DESCRIPTION

Veriexec loads entries to the in-kernel database from a file describing files to be monitored and the type of monitoring. This file is often referred to as the ‘signatures database’ or ‘signatures file’.

The signatures file can be easily created using veriexecgen(8).

SIGNATURES DATABASE FORMAT

The signatures database has a line based structure, where each line has several fields separated by white-space (space, tabs, etc.) taking the following form:

path type fingerprint flags

The description for each field is as follows:

path

The full path to the file. White-space characters can be escaped if prefixed with a ‘\’.

type

Type of fingerprinting algorithm used for the file.

Requires kernel support for the specified algorithm. List of fingerprinting algorithms supported by the kernel can be obtained by using the following command:

# sysctl kern.veriexec.algorithms

fingerprint

The fingerprint for the file. Can (usually) be generated using the following command:

% cksum -a <algorithm> <file>

flags

Optional listing of entry flags, separated by a comma. These may include:

direct

Allow direct execution only.

Execution of a program is said to be “direct” when the program is invoked by the user (either in a script, manually typing it, etc.) via the execve(2) syscall.

indirect

Allow indirect execution only.

Execution of a program is said to be “indirect” if it is invoked by the kernel to interpret a script (“hash-bang”).

file

Allow opening the file only, via the open(2) syscall (no execution is allowed).

untrusted

Indicate that the file is located on untrusted storage and its fingerprint evaluation status should not be cached, but rather re-calculated each time it is accessed.

Fingerprints for untrusted files will always be evaluated on load.

To improve readability of the signatures file, the following aliases are provided:

program

An alias for “direct”.

interpreter

An alias for “indirect”

script

An alias for both “direct” and “file”.

library

An alias for both “file” and “indirect”.

If no flags are specified, “direct” is assumed.

Comments begin with a ‘#’ character and span to the end of the line.

SEE ALSO

veriexec(4), security(7), veriexec(8), veriexecctl(8), veriexecgen(8)

HISTORY

veriexec first appeared in NetBSD 2.0.

AUTHORS

Brett Lymn <blymn@NetBSD.org> Elad Efrat <elad@NetBSD.org>