pg_exec

This repository provides a script and other resources for obtaining command execution from access to a PostgreSQL service, version 8.2 or later. Given credentials for a PostgreSQL service, the script will use SQL queries to upload a C library which contains a wrapper method around libc's system, and can be called using PostgreSQL's external function mechanisms. The script will then execute the given command on the system.

Please make sure to test the script on a local test install of PostgreSQL before attempting to use it against any live systems

The help text for the script is as follows:

$ ./pg_exec.sh --help
./pg_exec.sh [options]
 Execute a shell commands on a server using PostgreSQL access
 Options:
        --help                  Show this help text and exit
        -U, --user              The username to authenticate to the PostgreSQL server with
        -P, --password          The password to authenticate to the PostgreSQl server with
        -L, --library           A library to upload to the server instead of the default
        -S, --splitdir          The temporary directory to store the split parts of the library in
        -h, --host              The host running the PostgreSQL service
        -p, --port              The port that the PostgreSQL service is running on
        -c, --command           The command to execute on the server
        -e, --export            The path to save the library to on the server
        -s, --source            The source file to compile the library from
        -f, --function          The name of the function to be called in the library

The libraries directory contains pre-compiled libraries for the 9.x branch, which can be used with the "-L" flag. To use your own library you will have to install PostgreSQL from source. The major version installed must match that used by the target server.

This script requires the PostgreSQL binaries to be in the path. If you have installed from source following the included instructions, then run the script using:

PATH="/usr/local/pgsql/bin:$PATH" ./pg_exec.sh

Build using Docker

The Docker image is published on: https://hub.docker.com/repository/docker/martinvw/pg_exec

Cross compiling for Apple Silicon

Add platform to cross-compile on eg. Mac silicon: --platform linux/amd64

Note that this is slow, so running it natively on an old machine might make more sense.

Build the image from source (optional)

docker build . -t martinvw/pg_exec:latest

Use the docker image

docker run --rm -v "$(pwd)/libraries:/opt/pg_exec/libraries" -e PG_MAJOR=11 martinvw/pg_exec

Building multiple versions:

while read v; do docker run --rm -v "$(pwd)/libraries:/opt/pg_exec/libraries" -e PG_MAJOR=$v martinvw/pg_exec; done < versions.txt