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use std::{os::{unix::prelude::PermissionsExt, linux::fs::MetadataExt}, fs, io::{self, ErrorKind}};
use nix::unistd::{self, Uid};
/// Writes a file securly to a specified path with given data
/// #### Arguments
/// * `dir` - The directory of the secure folder
/// * `file` - The file name to write
/// * `data` - The data to write
/// #### Returns
/// A ``io::Result<()>`` if the write succeded or failed
pub fn write_file(dir: &str, file: &str, data: &str) -> Result<(), io::Error> {
fs::create_dir_all(dir)?;
set_file_permissions(0, 0, 0o100600, dir)?;
let path = path(dir, file);
fs::write(&path, data)?;
set_file_permissions(0, 0, 0o100600, &path)?;
Ok(())
}
/// Reads the file secutly to a specified path. If the file has
/// been tampered (permissions have been changed), it ignores the
/// file.
/// #### Arguments
/// * `dir` - The directory of the secure folder
/// * `file` - The file name to write
/// #### Returns
/// * `None` - If the files doesnt exist or isnt trusted
/// * `Some(String) - If the file is trusted, it returns the file's contents
pub fn read_file(dir: &str, file: &str) -> Option<String> {
let path = path(dir,file);
if !check_file_permissions(0, 0, 0o100600, &path) {
return None;
}
match fs::read_to_string(&path) {
Ok(data) => return Some(data),
Err(_) => return None
};
}
/// Elecate the privlages of the current process
/// #### Arguments
/// * `uid` - The uid to set the process to
/// #### Returns
/// If the process fails to elevate, it returns false
pub fn elevate_privilages(uid: Uid) -> bool {
if unistd::setuid(uid).is_err() {
return false;
}
true
}
/// Sets the permission for a secure file
/// #### Arguments
/// * `uid` - The user to own the file
/// * `gid` - The group to own the file
/// * `mode` - The mode permissions of the file
/// * `path` - The path of the secure file
/// #### Returns
/// A ``io::Result<()>`` if the write succeded or failed
fn set_file_permissions(uid: u32, gid: u32, mode: u32, path: &str) -> Result<(), io::Error> {
unistd::chown(std::path::Path::new(path), Some(unistd::Uid::from(uid)), Some(unistd::Gid::from(gid)))?;
let metadata = fs::metadata(path)?;
let mut perms = metadata.permissions();
perms.set_mode(mode);
fs::set_permissions(path, perms)?;
Ok(())
}
/// Checks if the files permissions equals the given parameters
/// #### Arguments
/// * `uid` - The user to own the file
/// * `gid` - The group to own the file
/// * `mode` - The mode permissions of the file
/// * `path` - The path of the secure file
/// #### Returns
/// True or false if the files permissions match
fn check_file_permissions(uid: u32, gid: u32, mode: u32, path: &str) -> bool {
let metadata = match fs::metadata(path) {
Ok(data) => data,
Err(e) => {
return e.kind() == ErrorKind::NotFound;
}
};
let perms = metadata.permissions();
return perms.mode() == mode && metadata.st_uid() == uid && metadata.st_gid() == gid;
}
/// Get the path of a file given a directory and file name
fn path(dir: &str, file: &str) -> String {
return format!("{}/{}.persist", dir, file);
}
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