Fully check xattr format; fill in user. prefix when absent

Cargo.lock

@@ -2,6 +2,15 @@
 # It is not intended for manual editing.
 version = 3
 
+[[package]]
+name = "aho-corasick"
+version = "1.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "43f6cb1bf222025340178f382c426f13757b2960e89779dfcb319c32542a5a41"
+dependencies = [
+ "memchr",
+]
+
 [[package]]
 name = "anstream"
 version = "0.3.2"
@@ -169,6 +178,12 @@ version = "1.0.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "af150ab688ff2122fcef229be89cb50dd66af9e01a4ff320cc137eecc9bacc38"
 
+[[package]]
+name = "lazy_static"
+version = "1.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
+
 [[package]]
 name = "libc"
 version = "0.2.147"
@@ -187,12 +202,21 @@ version = "0.2.1"
 dependencies = [
  "clap",
  "clap_complete",
+ "lazy_static",
+ "regex",
  "serde",
  "serde_json",
+ "thiserror",
  "walkdir",
  "xattr",
 ]
 
+[[package]]
+name = "memchr"
+version = "2.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2dffe52ecf27772e601905b7522cb4ef790d2cc203488bbd0e2fe85fcb74566d"
+
 [[package]]
 name = "once_cell"
 version = "1.18.0"
@@ -217,6 +241,35 @@ dependencies = [
  "proc-macro2",
 ]
 
+[[package]]
+name = "regex"
+version = "1.9.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b2eae68fc220f7cf2532e4494aded17545fce192d59cd996e0fe7887f4ceb575"
+dependencies = [
+ "aho-corasick",
+ "memchr",
+ "regex-automata",
+ "regex-syntax",
+]
+
+[[package]]
+name = "regex-automata"
+version = "0.3.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b7b6d6190b7594385f61bd3911cd1be99dfddcfc365a4160cc2ab5bff4aed294"
+dependencies = [
+ "aho-corasick",
+ "memchr",
+ "regex-syntax",
+]
+
+[[package]]
+name = "regex-syntax"
+version = "0.7.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e5ea92a5b6195c6ef2a0295ea818b312502c6fc94dde986c5553242e18fd4ce2"
+
 [[package]]
 name = "rustix"
 version = "0.38.4"
@@ -293,6 +346,26 @@ dependencies = [
  "unicode-ident",
 ]
 
+[[package]]
+name = "thiserror"
+version = "1.0.44"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "611040a08a0439f8248d1990b111c95baa9c704c805fa1f62104b39655fd7f90"
+dependencies = [
+ "thiserror-impl",
+]
+
+[[package]]
+name = "thiserror-impl"
+version = "1.0.44"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "090198534930841fab3a5d1bb637cde49e339654e606195f8d9c76eeb081dc96"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "unicode-ident"
 version = "1.0.11"

Cargo.toml

@@ -9,8 +9,11 @@ build = "build.rs"
 
 [dependencies]
 clap = { version = "4.3.19", features = ["derive"] }
+lazy_static = "1.4.0"
+regex = "1.9.1"
 serde = { version = "1.0.163", features = ["derive"] }
 serde_json = "1.0.96"
+thiserror = "1.0.44"
 walkdir = "2.3.3"
 xattr = { version = "1.0.0", default-features = false }
 

src/bin/mtr.rs

@@ -6,7 +6,11 @@ use std::{
 };
 
 use clap::{Parser, Subcommand};
+#[macro_use]
+extern crate lazy_static;
+use regex::Regex;
 use serde::Serialize;
+use thiserror::Error;
 use walkdir::WalkDir;
 
 const XATTR_KEYNAME: &'static str = "user.mattress.keyname";
@@ -25,6 +29,11 @@ struct FileXattrs {
     xattrs: HashMap<String, String>,
 }
 
+lazy_static! {
+    static ref RE_XATTR: Regex = Regex::new("^([^.]+[.])([^.]+)$").unwrap();
+    static ref RE_XATTR_NO_NAMESPACE: Regex = Regex::new("^[^.]+$").unwrap();
+}
+
 #[derive(Subcommand)]
 enum Commands {
     /// Copy xattr values from one path to another.
@@ -98,7 +107,70 @@ enum CopyOrMove {
     Move,
 }
 
+#[derive(Error, Debug)]
+enum StandardizeXattrError {
+    #[error("Extended attribute was empty")]
+    Empty,
+    #[error("Illegal format of extended attribute '{0}'")]
+    BadXattr(String),
+    #[error("Illegal namespace '{0}'")]
+    IllegalNamespace(String),
+}
+
+/// Checks the form of xattrs
+/// They must either be namespace.attr or just plain xattr
+/// When the namespace is not provided it will be filled in with "user"
+fn standardize_xattr(xattr: &str) -> Result<String, StandardizeXattrError> {
+    if xattr.is_empty() {
+        return Err(StandardizeXattrError::Empty);
+    }
+
+    if let Some(captures) = RE_XATTR.captures(xattr) {
+        debug_assert!(captures.len() > 1);
+
+        let (_, [mut namespace, attr]) = captures.extract();
+
+        if namespace.len() == 0 {
+            namespace = "user."; // default to the user namespace
+        }
+
+        if !(namespace == "user."
+            || namespace == "trusted."
+            || namespace == "system."
+            || namespace == "security.")
+        {
+            Err(StandardizeXattrError::IllegalNamespace(
+                namespace.to_string(),
+            ))
+        } else {
+            Ok(format!("{}{}", namespace, attr))
+        }
+    } else {
+        if let Some(_captures) = RE_XATTR_NO_NAMESPACE.captures(xattr) {
+            Ok(format!("user.{}", xattr))
+        } else {
+            Err(StandardizeXattrError::BadXattr(xattr.to_string()))
+        }
+    }
+}
+
+/// Ensure xattr names are prefixed by `user.` and otherwise properly formatted
+/// See standardize_xattr`
+fn standardize_xattrs(xattrs: &Vec<String>) -> Vec<String> {
+    xattrs
+        .iter()
+        .map(|xattr| xattr.as_str())
+        .map(|f| {
+            standardize_xattr(f).unwrap_or_else(|e| {
+                panic!("xattr {} formatted incorrectly: {}", f, e);
+            })
+        })
+        .collect()
+}
+
 fn cp_or_mv(src: &PathBuf, dest: &PathBuf, fields: &Vec<String>, verbose: &bool, kind: CopyOrMove) {
+    let fields = standardize_xattrs(fields);
+
     let fields: Vec<String> = if fields.is_empty() {
         xattr::list(src)
             .unwrap_or_else(|e| panic!("Could not list xattrs on {}: {}", src.display(), e))
@@ -153,6 +225,9 @@ fn rm(paths: &Vec<PathBuf>, fields: &Vec<String>, verbose: &bool) {
     if *verbose {
         eprintln!("Removing {} from:", fields.join(", "));
     }
+
+    let fields = standardize_xattrs(fields);
+
     for path in paths {
         let fields: Vec<String> = if fields.is_empty() {
             xattr::list(path)
@@ -180,6 +255,8 @@ fn rm(paths: &Vec<PathBuf>, fields: &Vec<String>, verbose: &bool) {
 }
 
 fn get(paths: &Vec<PathBuf>, fields: &Vec<String>, json: &bool) {
+    let fields = standardize_xattrs(fields);
+
     for path in paths {
         let fields: Vec<String> = if fields.is_empty() {
             xattr::list(path)
@@ -259,7 +336,11 @@ fn set<P: AsRef<Path>>(paths: &Vec<P>, field_assignments: &Vec<String>, verbose:
                 );
             }
 
-            (parts[0].to_string(), parts[1].to_string())
+            (
+                standardize_xattr(parts[0])
+                    .unwrap_or_else(|e| panic!("Error standardizing xattr {}: {}", parts[0], e)),
+                parts[1].to_string(),
+            )
         })
         .collect();
 
@@ -287,17 +368,7 @@ fn idx(src: &PathBuf, dest: &PathBuf, keys: &Vec<String>, verbose: &bool) {
         panic!("No keys were provided to index by");
     }
 
-    // Make add user. prefix if missing
-    let keys: Vec<String> = keys
-        .iter()
-        .map(|key| {
-            if key.starts_with("user.") {
-                key.clone()
-            } else {
-                format!("user.{}", key)
-            }
-        })
-        .collect();
+    let keys = standardize_xattrs(keys);
 
     for entry in WalkDir::new(src) {
         let entry = entry.unwrap_or_else(|e| panic!("Could not read directory: {}", e));