elfctl1

Usage

Overview

The elfctl utility modifies feature flags in the feature control note in an ELF binary.

The options are as follows:

-h | --help

Print a usage message and exit.

-i

Ignore unknown feature flags in featurelist.

-l

List known ELF feature flags.

-e featurelist

Edit features from the given comma separated list featurelist. featurelist starts with one of the three operations: “+” to turn on the features, “-” to turn off the features, “=” to only turn on the given features. A comma separated list of feature names or numeric values follows the operation.

If -e is not specified elfctl displays the status of each feature in the ELF note in each file ....

Exit status

Exit status is 0 on success, and 1 if the command fails if a file does not exist, is too short, or fails to find or edit features note.

Examples

The following is an example of a typical usage of the elfctl command:

elfctl file
elfctl -e +noaslr file

Features may be specified as numerical values:

elfctl -e =0x0001,0x0004 file

Features may also be specified as a single combined value:

elfctl -e =0x5 file

Notes

On amd64, on a machine with LA57 (5-level paging) mode supported and enabled, if both la57 and la48 feature flags are specified, the la57 feature has priority over la48. The vm.pmap.prefer_uva_la48 sysctl MIB defines the default user address space size for binaries which do not set either of these flags.