| 1 | //! Expand a shell command line into the set of commands a shell would run. |
| 2 | //! |
| 3 | //! Deny rules are the one gate that holds under `AskForApproval::Never`, so |
| 4 | //! they cannot be matched against the raw command string: the string a user |
| 5 | //! types and the set of commands the shell executes are different things. A |
| 6 | //! command substitution runs its body (`` `rm -rf /` ``, `$(rm -rf /)`), a |
| 7 | //! quoted argument executes with the quotes removed (`rm -rf "/"`), and a |
| 8 | //! wrapper hands its payload straight back to a shell (`bash -c '…'`, |
| 9 | //! `eval '…'`, `sudo …`). |
| 10 | //! |
| 11 | //! Matching one string pattern per metacharacter loses that race by |
| 12 | //! construction — every new quoting or wrapping form is another bypass. This |
| 13 | //! module instead tokenizes the command the way a POSIX shell word-splits it |
| 14 | //! and returns *every* command line that would actually be executed, so deny |
| 15 | //! rules can be matched against each one. |
| 16 | //! |
| 17 | //! Deliberately conservative in the deny direction: when a construct is |
| 18 | //! ambiguous the expander emits extra candidate command lines rather than |
| 19 | //! fewer. Over-emitting only makes deny matching stricter — `denied_prefix_matches` |
| 20 | //! stays anchored at the first positional token, so an extra candidate that no |
| 21 | //! rule names is inert. Under-emitting is a bypass. |
| 22 | //! |
| 23 | //! What it does *not* do is evaluate anything: `$VAR` is left as literal text, |
| 24 | //! and single-quoted text is never treated as code (`echo '` + "`" + `rm -rf /`" + |
| 25 | //! "`" + `'` really does just print). Fidelity to shell semantics is the point in |
| 26 | //! both directions. |
| 27 | |
| 28 | use std::collections::HashSet; |
| 29 | |
| 30 | /// Maximum nesting depth followed through substitutions and `-c` payloads. |
| 31 | const MAX_DEPTH: usize = 8; |
| 32 | |
| 33 | /// Upper bound on emitted command lines, so a pathological input cannot turn |
| 34 | /// one policy check into unbounded work. |
| 35 | const MAX_COMMANDS: usize = 256; |
| 36 | |
| 37 | /// How far into a command the search for a wrapper head (`bash -c`, `eval`) |
| 38 | /// will walk past flags and wrapper words. |
| 39 | const MAX_HEAD_SCAN: usize = 8; |
| 40 | |
| 41 | /// Words that prefix another command rather than being the command: the real |
| 42 | /// invocation is what follows. Stripping them keeps `sudo rm -rf /` matchable |
| 43 | /// by an `rm -rf /` rule. |
| 44 | const PASSTHROUGH_WRAPPERS: &[&str] = &[ |
| 45 | "sudo", "doas", "env", "nohup", "nice", "ionice", "time", "timeout", "stdbuf", "setsid", |
| 46 | "command", "builtin", "exec", "xargs", "unbuffer", "busybox", "chroot", "proot", |
| 47 | ]; |
| 48 | |
| 49 | /// Shells whose `-c` argument is a command line to be parsed, not an operand. |
| 50 | const SHELL_NAMES: &[&str] = &[ |
| 51 | "sh", "bash", "zsh", "dash", "ksh", "ksh93", "mksh", "ash", "fish", "csh", "tcsh", "rbash", |
| 52 | "yash", |
| 53 | ]; |
| 54 | |
| 55 | /// Returns every command line the shell would execute for `command`. |
| 56 | /// |
| 57 | /// The raw input is always included first, so callers keep whatever matching |
| 58 | /// they already did against it. Subsequent entries are the word-split, quote- |
| 59 | /// stripped command lines drawn from top-level chaining, command substitutions, |
| 60 | /// process substitutions, grouping, and wrapper payloads. Results are |
| 61 | /// de-duplicated and order-stable. |
| 62 | pub fn expanded_commands(command: &str) -> Vec<String> { |
| 63 | let mut expander = Expander { |
| 64 | out: Vec::new(), |
| 65 | seen: HashSet::new(), |
| 66 | }; |
| 67 | let trimmed = command.trim(); |
| 68 | if !trimmed.is_empty() { |
| 69 | expander.seen.insert(trimmed.to_string()); |
| 70 | expander.out.push(trimmed.to_string()); |
| 71 | } |
| 72 | expander.expand(command, 0); |
| 73 | expander.out |
| 74 | } |
| 75 | |
| 76 | struct Expander { |
| 77 | out: Vec<String>, |
| 78 | seen: HashSet<String>, |
| 79 | } |
| 80 | |
| 81 | impl Expander { |
| 82 | fn emit(&mut self, tokens: &[String]) { |
| 83 | if self.out.len() >= MAX_COMMANDS { |
| 84 | return; |
| 85 | } |
| 86 | let joined = tokens |
| 87 | .iter() |
| 88 | .filter(|token| !token.is_empty()) |
| 89 | .cloned() |
| 90 | .collect::<Vec<_>>() |
| 91 | .join(" "); |
| 92 | if joined.is_empty() { |
| 93 | return; |
| 94 | } |
| 95 | if self.seen.insert(joined.clone()) { |
| 96 | self.out.push(joined); |
| 97 | } |
| 98 | } |
| 99 | |
| 100 | /// Word-split `input` into command lines and record each one, recursing |
| 101 | /// into every nested command text found along the way. |
| 102 | fn expand(&mut self, input: &str, depth: usize) { |
| 103 | if depth > MAX_DEPTH || self.out.len() >= MAX_COMMANDS { |
| 104 | return; |
| 105 | } |
| 106 | let chars: Vec<char> = input.chars().collect(); |
| 107 | let n = chars.len(); |
| 108 | let mut i = 0usize; |
| 109 | let mut commands: Vec<Vec<String>> = Vec::new(); |
| 110 | let mut words: Vec<String> = Vec::new(); |
| 111 | let mut word = String::new(); |
| 112 | let mut started = false; |
| 113 | let mut nested: Vec<String> = Vec::new(); |
| 114 | |
| 115 | while i < n { |
| 116 | let c = chars[i]; |
| 117 | match c { |
| 118 | // A backslash outside quotes escapes exactly one character, |
| 119 | // including an operator: `echo a\;b` is one word, not two |
| 120 | // commands. A backslash-newline is a line continuation. |
| 121 | '\\' => { |
| 122 | if i + 1 < n { |
| 123 | if chars[i + 1] != '\n' { |
| 124 | word.push(chars[i + 1]); |
| 125 | started = true; |
| 126 | } |
| 127 | i += 2; |
| 128 | } else { |
| 129 | i += 1; |
| 130 | } |
| 131 | } |
| 132 | // Single quotes are fully literal: no substitution, no escapes. |
| 133 | '\'' => { |
| 134 | started = true; |
| 135 | i += 1; |
| 136 | while i < n && chars[i] != '\'' { |
| 137 | word.push(chars[i]); |
| 138 | i += 1; |
| 139 | } |
| 140 | i = (i + 1).min(n); |
| 141 | } |
| 142 | // Double quotes suppress word splitting but NOT substitution. |
| 143 | '"' => { |
| 144 | started = true; |
| 145 | i += 1; |
| 146 | while i < n && chars[i] != '"' { |
| 147 | match chars[i] { |
| 148 | '\\' if i + 1 < n => { |
| 149 | word.push(chars[i + 1]); |
| 150 | i += 2; |
| 151 | } |
| 152 | '`' => { |
| 153 | let (inner, next) = read_backtick(&chars, i); |
| 154 | nested.push(inner); |
| 155 | i = next; |
| 156 | } |
| 157 | '$' if i + 1 < n && chars[i + 1] == '(' => { |
| 158 | let (inner, next) = read_delimited(&chars, i + 1, '(', ')'); |
| 159 | nested.push(inner); |
| 160 | i = next; |
| 161 | } |
| 162 | '$' if i + 1 < n && chars[i + 1] == '{' => { |
| 163 | let (inner, next) = read_delimited(&chars, i + 1, '{', '}'); |
| 164 | nested.push(inner); |
| 165 | i = next; |
| 166 | } |
| 167 | ch => { |
| 168 | word.push(ch); |
| 169 | i += 1; |
| 170 | } |
| 171 | } |
| 172 | } |
| 173 | i = (i + 1).min(n); |
| 174 | } |
| 175 | // `$'…'` (ANSI-C quoting) is literal text with C escapes. |
| 176 | '$' if i + 1 < n && chars[i + 1] == '\'' => { |
| 177 | started = true; |
| 178 | i += 2; |
| 179 | while i < n && chars[i] != '\'' { |
| 180 | if chars[i] == '\\' && i + 1 < n { |
| 181 | word.push(chars[i + 1]); |
| 182 | i += 2; |
| 183 | } else { |
| 184 | word.push(chars[i]); |
| 185 | i += 1; |
| 186 | } |
| 187 | } |
| 188 | i = (i + 1).min(n); |
| 189 | } |
| 190 | // Command substitution, both spellings. The body is a command |
| 191 | // line in its own right; the substitution contributes no text |
| 192 | // to the enclosing word (we do not evaluate output). |
| 193 | '`' => { |
| 194 | let (inner, next) = read_backtick(&chars, i); |
| 195 | nested.push(inner); |
| 196 | i = next; |
| 197 | } |
| 198 | '$' if i + 1 < n && chars[i + 1] == '(' => { |
| 199 | let (inner, next) = read_delimited(&chars, i + 1, '(', ')'); |
| 200 | nested.push(inner); |
| 201 | i = next; |
| 202 | } |
| 203 | // `${…}` is an expansion, not a command — but it can *contain* |
| 204 | // one (`${x:-$(rm -rf /)}`), so the body is rescanned. |
| 205 | '$' if i + 1 < n && chars[i + 1] == '{' => { |
| 206 | let (inner, next) = read_delimited(&chars, i + 1, '{', '}'); |
| 207 | nested.push(inner); |
| 208 | i = next; |
| 209 | } |
| 210 | // Process substitution `<(…)` / `>(…)` also runs its body. |
| 211 | '<' | '>' if i + 1 < n && chars[i + 1] == '(' => { |
| 212 | let (inner, next) = read_delimited(&chars, i + 1, '(', ')'); |
| 213 | nested.push(inner); |
| 214 | i = next; |
| 215 | } |
| 216 | ' ' | '\t' => { |
| 217 | flush_word(&mut words, &mut word, &mut started); |
| 218 | i += 1; |
| 219 | } |
| 220 | // A subshell boundary. `$(`, `<(` and `>(` were consumed by the |
| 221 | // arms above, so a bare paren here is grouping: the body is a |
| 222 | // command list of its own, not part of the surrounding word. |
| 223 | '(' | ')' => { |
| 224 | flush_word(&mut words, &mut word, &mut started); |
| 225 | end_command(&mut commands, &mut words); |
| 226 | i += 1; |
| 227 | } |
| 228 | // Control operators end the current command line. `&&`, `||`, |
| 229 | // `;;`, `|&` and runs of newlines collapse into one break. |
| 230 | '\n' | '\r' | ';' | '&' | '|' => { |
| 231 | flush_word(&mut words, &mut word, &mut started); |
| 232 | end_command(&mut commands, &mut words); |
| 233 | i += 1; |
| 234 | while i < n && matches!(chars[i], '\n' | '\r' | ';' | '&' | '|') { |
| 235 | i += 1; |
| 236 | } |
| 237 | } |
| 238 | _ => { |
| 239 | word.push(c); |
| 240 | started = true; |
| 241 | i += 1; |
| 242 | } |
| 243 | } |
| 244 | } |
| 245 | flush_word(&mut words, &mut word, &mut started); |
| 246 | end_command(&mut commands, &mut words); |
| 247 | |
| 248 | for tokens in &commands { |
| 249 | self.record(tokens, depth); |
| 250 | } |
| 251 | for inner in nested { |
| 252 | self.expand(&inner, depth + 1); |
| 253 | } |
| 254 | } |
| 255 | |
| 256 | /// Record one word-split command line, plus the invocation hiding inside it |
| 257 | /// when the head is a wrapper. |
| 258 | fn record(&mut self, tokens: &[String], depth: usize) { |
| 259 | if tokens.is_empty() { |
| 260 | return; |
| 261 | } |
| 262 | self.emit(tokens); |
| 263 | |
| 264 | // `sudo rm -rf /` is an `rm -rf /`. Strip wrapper words (and the scalar |
| 265 | // arguments that belong to them, e.g. `timeout 5`) and emit what's left. |
| 266 | let stripped = strip_leading_wrappers(tokens); |
| 267 | if stripped.len() != tokens.len() { |
| 268 | self.emit(stripped); |
| 269 | } |
| 270 | |
| 271 | // `eval …` and `sh -c …` take a *command line* as data. Parse it. |
| 272 | if let Some(head) = find_wrapper_head(tokens) { |
| 273 | let name = basename(&tokens[head]).to_ascii_lowercase(); |
| 274 | if name == "eval" { |
| 275 | let payload = tokens[head + 1..].join(" "); |
| 276 | self.expand(&payload, depth + 1); |
| 277 | } else if let Some(script) = shell_c_argument(&tokens[head..]) { |
| 278 | self.expand(script, depth + 1); |
| 279 | } |
| 280 | } |
| 281 | } |
| 282 | } |
| 283 | |
| 284 | fn flush_word(words: &mut Vec<String>, word: &mut String, started: &mut bool) { |
| 285 | if *started || !word.is_empty() { |
| 286 | words.push(std::mem::take(word)); |
| 287 | *started = false; |
| 288 | } |
| 289 | } |
| 290 | |
| 291 | fn end_command(commands: &mut Vec<Vec<String>>, words: &mut Vec<String>) { |
| 292 | // `{` and `}` stand alone as reserved words in `{ cmd; }` — they group a |
| 293 | // command rather than being part of one. Dropping them here keeps every |
| 294 | // downstream consumer (wrapper detection, emission) looking at real |
| 295 | // command words only. |
| 296 | words.retain(|word| !matches!(word.as_str(), "{" | "}")); |
| 297 | if !words.is_empty() { |
| 298 | commands.push(std::mem::take(words)); |
| 299 | } |
| 300 | } |
| 301 | |
| 302 | /// Read a backtick substitution. `start` indexes the opening backtick; returns |
| 303 | /// the body and the index just past the closing backtick. |
| 304 | fn read_backtick(chars: &[char], start: usize) -> (String, usize) { |
| 305 | let mut i = start + 1; |
| 306 | let mut inner = String::new(); |
| 307 | while i < chars.len() { |
| 308 | match chars[i] { |
| 309 | '\\' if i + 1 < chars.len() => { |
| 310 | inner.push(chars[i]); |
| 311 | inner.push(chars[i + 1]); |
| 312 | i += 2; |
| 313 | } |
| 314 | '`' => return (inner, i + 1), |
| 315 | c => { |
| 316 | inner.push(c); |
| 317 | i += 1; |
| 318 | } |
| 319 | } |
| 320 | } |
| 321 | (inner, i) |
| 322 | } |
| 323 | |
| 324 | /// Read a balanced `open`/`close` region. `open_at` indexes the opening |
| 325 | /// delimiter; returns the body and the index just past the matching close. |
| 326 | fn read_delimited(chars: &[char], open_at: usize, open: char, close: char) -> (String, usize) { |
| 327 | let mut depth = 1usize; |
| 328 | let mut i = open_at + 1; |
| 329 | let mut inner = String::new(); |
| 330 | while i < chars.len() { |
| 331 | let c = chars[i]; |
| 332 | if c == '\\' && i + 1 < chars.len() { |
| 333 | inner.push(c); |
| 334 | inner.push(chars[i + 1]); |
| 335 | i += 2; |
| 336 | continue; |
| 337 | } |
| 338 | if c == open { |
| 339 | depth += 1; |
| 340 | } else if c == close { |
| 341 | depth -= 1; |
| 342 | if depth == 0 { |
| 343 | return (inner, i + 1); |
| 344 | } |
| 345 | } |
| 346 | inner.push(c); |
| 347 | i += 1; |
| 348 | } |
| 349 | (inner, i) |
| 350 | } |
| 351 | |
| 352 | /// The final path component, so `/usr/bin/sudo` reads as `sudo`. |
| 353 | fn basename(token: &str) -> &str { |
| 354 | token |
| 355 | .rsplit(['/', '\\']) |
| 356 | .next() |
| 357 | .filter(|part| !part.is_empty()) |
| 358 | .unwrap_or(token) |
| 359 | } |
| 360 | |
| 361 | fn is_env_assignment(token: &str) -> bool { |
| 362 | match token.split_once('=') { |
| 363 | Some((name, _)) => { |
| 364 | !name.is_empty() |
| 365 | && !name.starts_with('-') |
| 366 | && name |
| 367 | .chars() |
| 368 | .all(|ch| ch.is_ascii_alphanumeric() || ch == '_') |
| 369 | } |
| 370 | None => false, |
| 371 | } |
| 372 | } |
| 373 | |
| 374 | /// True for a bare scalar operand that belongs to a wrapper word rather than |
| 375 | /// starting a command — `timeout 5`, `nice -n 10`, `timeout 1.5s`. |
| 376 | fn is_scalar_operand(token: &str) -> bool { |
| 377 | let body = token.trim_end_matches(['s', 'm', 'h', 'd']); |
| 378 | !body.is_empty() && body.chars().all(|ch| ch.is_ascii_digit() || ch == '.') |
| 379 | } |
| 380 | |
| 381 | fn is_passthrough_wrapper(token: &str) -> bool { |
| 382 | let name = basename(token).to_ascii_lowercase(); |
| 383 | PASSTHROUGH_WRAPPERS.contains(&name.as_str()) |
| 384 | } |
| 385 | |
| 386 | fn is_shell_name(token: &str) -> bool { |
| 387 | let name = basename(token).to_ascii_lowercase(); |
| 388 | SHELL_NAMES.contains(&name.as_str()) |
| 389 | } |
| 390 | |
| 391 | /// Drop leading environment assignments, wrapper words, and the scalar operands |
| 392 | /// those wrappers take, returning the remaining slice. |
| 393 | /// |
| 394 | /// Flags are deliberately *not* dropped: `denied_prefix_matches` already skips |
| 395 | /// unrelated flags (and, ambiguously, their values) when anchoring a rule, so |
| 396 | /// leaving `-u root` in place is both correct and matchable. |
| 397 | fn strip_leading_wrappers(tokens: &[String]) -> &[String] { |
| 398 | let mut start = 0usize; |
| 399 | let mut dropped_wrapper = false; |
| 400 | while start < tokens.len() { |
| 401 | let token = &tokens[start]; |
| 402 | if is_env_assignment(token) { |
| 403 | start += 1; |
| 404 | } else if is_passthrough_wrapper(token) { |
| 405 | dropped_wrapper = true; |
| 406 | start += 1; |
| 407 | } else if dropped_wrapper && is_scalar_operand(token) { |
| 408 | start += 1; |
| 409 | } else { |
| 410 | break; |
| 411 | } |
| 412 | } |
| 413 | &tokens[start..] |
| 414 | } |
| 415 | |
| 416 | /// Index of the `eval` / shell word that introduces a nested command line, if |
| 417 | /// this invocation has one. |
| 418 | /// |
| 419 | /// The scan walks past environment assignments, wrapper words, flags, and the |
| 420 | /// operand immediately following a single-dash flag (which may be that flag's |
| 421 | /// value, as in `sudo -u root bash -c …`). It stops at the first token that |
| 422 | /// cannot plausibly precede the real command, which is what keeps |
| 423 | /// `echo bash -c 'rm -rf /'` — a command that only prints — from being read as |
| 424 | /// a shell invocation. |
| 425 | fn find_wrapper_head(tokens: &[String]) -> Option<usize> { |
| 426 | let mut previous_was_short_flag = false; |
| 427 | for (index, token) in tokens.iter().enumerate().take(MAX_HEAD_SCAN) { |
| 428 | if is_shell_name(token) || basename(token).eq_ignore_ascii_case("eval") { |
| 429 | return Some(index); |
| 430 | } |
| 431 | let skippable = is_env_assignment(token) |
| 432 | || is_passthrough_wrapper(token) |
| 433 | || token.starts_with('-') |
| 434 | || is_scalar_operand(token) |
| 435 | || previous_was_short_flag; |
| 436 | if !skippable { |
| 437 | return None; |
| 438 | } |
| 439 | previous_was_short_flag = token.starts_with('-') && !token.starts_with("--"); |
| 440 | } |
| 441 | None |
| 442 | } |
| 443 | |
| 444 | /// The command-line argument of a shell's `-c` flag, if present. |
| 445 | /// |
| 446 | /// `tokens[0]` is the shell. Combined short flags count (`bash -lc '…'`). |
| 447 | /// The scan deliberately does NOT stop at the first non-flag operand: an |
| 448 | /// earlier version did, and `bash -o vi -c 'payload'` walked straight past |
| 449 | /// the deny expander because `vi` (the argument of `-o`) ended the scan |
| 450 | /// before `-c` was seen (2026-08-04 review). Continuing the scan can |
| 451 | /// over-read a `-c` that is really an argument to a script |
| 452 | /// (`bash script.sh -c x`), but this expander's contract is explicit that |
| 453 | /// over-emitting targets is safe and under-emitting is a bypass. |
| 454 | fn shell_c_argument(tokens: &[String]) -> Option<&str> { |
| 455 | let mut index = 1usize; |
| 456 | while index < tokens.len() { |
| 457 | let token = tokens[index].as_str(); |
| 458 | let takes_command_line = match token.strip_prefix("--") { |
| 459 | Some(long) => long.eq_ignore_ascii_case("command"), |
| 460 | None => token |
| 461 | .strip_prefix('-') |
| 462 | .is_some_and(|flags| flags.contains('c')), |
| 463 | }; |
| 464 | if takes_command_line { |
| 465 | return tokens.get(index + 1).map(String::as_str); |
| 466 | } |
| 467 | index += 1; |
| 468 | } |
| 469 | None |
| 470 | } |
| 471 | |
| 472 | #[cfg(test)] |
| 473 | mod tests { |
| 474 | use super::*; |
| 475 | |
| 476 | fn expand(command: &str) -> Vec<String> { |
| 477 | expanded_commands(command) |
| 478 | } |
| 479 | |
| 480 | fn contains(command: &str, expected: &str) -> bool { |
| 481 | expand(command).iter().any(|target| target == expected) |
| 482 | } |
| 483 | |
| 484 | #[test] |
| 485 | fn backtick_body_is_a_command() { |
| 486 | assert!(contains("`rm -rf /`", "rm -rf /")); |
| 487 | assert!(contains("echo `rm -rf /`", "rm -rf /")); |
| 488 | assert!(contains("echo `rm -rf /`", "echo")); |
| 489 | } |
| 490 | |
| 491 | #[test] |
| 492 | fn dollar_paren_body_is_a_command() { |
| 493 | assert!(contains("echo $(rm -rf /)", "rm -rf /")); |
| 494 | assert!(contains("x=$(rm -rf /)", "rm -rf /")); |
| 495 | assert!(contains("echo \"$(rm -rf /)\"", "rm -rf /")); |
| 496 | } |
| 497 | |
| 498 | #[test] |
| 499 | fn nested_substitution_is_followed() { |
| 500 | assert!(contains("echo $(echo `rm -rf /`)", "rm -rf /")); |
| 501 | } |
| 502 | |
| 503 | #[test] |
| 504 | fn quotes_are_removed_from_operands() { |
| 505 | assert!(contains("rm -rf \"/\"", "rm -rf /")); |
| 506 | assert!(contains("rm -rf '/'", "rm -rf /")); |
| 507 | assert!(contains("\"rm\" -rf /", "rm -rf /")); |
| 508 | assert!(contains("rm -r\"f\" /", "rm -rf /")); |
| 509 | } |
| 510 | |
| 511 | #[test] |
| 512 | fn single_quoted_text_is_not_a_command() { |
| 513 | // A literal backtick inside single quotes is printed, not executed. |
| 514 | let targets = expand("echo '`rm -rf /`'"); |
| 515 | assert!( |
| 516 | !targets.iter().any(|t| t == "rm -rf /"), |
| 517 | "single-quoted text must not become a command: {targets:?}" |
| 518 | ); |
| 519 | } |
| 520 | |
| 521 | #[test] |
| 522 | fn escaped_operators_do_not_split() { |
| 523 | let targets = expand("echo a\\;b"); |
| 524 | assert_eq!(targets.len(), 2, "{targets:?}"); |
| 525 | assert!(targets.contains(&"echo a;b".to_string()), "{targets:?}"); |
| 526 | } |
| 527 | |
| 528 | #[test] |
| 529 | fn control_operators_split_commands() { |
| 530 | for command in [ |
| 531 | "ls && rm -rf /", |
| 532 | "ls || rm -rf /", |
| 533 | "ls ; rm -rf /", |
| 534 | "ls | rm -rf /", |
| 535 | "ls & rm -rf /", |
| 536 | "ls\nrm -rf /", |
| 537 | ] { |
| 538 | assert!(contains(command, "rm -rf /"), "{command}"); |
| 539 | } |
| 540 | } |
| 541 | |
| 542 | #[test] |
| 543 | fn wrappers_and_payloads_are_unwrapped() { |
| 544 | for command in [ |
| 545 | "sudo rm -rf /", |
| 546 | "env rm -rf /", |
| 547 | "timeout 5 rm -rf /", |
| 548 | "nohup rm -rf /", |
| 549 | "xargs rm -rf /", |
| 550 | "/usr/bin/sudo rm -rf /", |
| 551 | "eval 'rm -rf /'", |
| 552 | "bash -c 'rm -rf /'", |
| 553 | "sh -lc \"rm -rf /\"", |
| 554 | "sudo -u root bash -c 'rm -rf /'", |
| 555 | // 2026-08-04: `-o vi` used to end the flag scan before `-c` was |
| 556 | // seen, so the payload skipped deny expansion entirely. |
| 557 | "bash -o vi -c 'rm -rf /'", |
| 558 | "zsh --norcs -c 'rm -rf /'", |
| 559 | ] { |
| 560 | assert!( |
| 561 | contains(command, "rm -rf /"), |
| 562 | "{command}: {:?}", |
| 563 | expand(command) |
| 564 | ); |
| 565 | } |
| 566 | } |
| 567 | |
| 568 | #[test] |
| 569 | fn wrapper_head_scan_stops_at_a_real_command() { |
| 570 | // `echo` prints its arguments; nothing here is executed as a shell. |
| 571 | let targets = expand("echo bash -c 'rm -rf /'"); |
| 572 | assert!( |
| 573 | !targets.iter().any(|t| t == "rm -rf /"), |
| 574 | "arguments of a printing command must not be parsed as code: {targets:?}" |
| 575 | ); |
| 576 | } |
| 577 | |
| 578 | #[test] |
| 579 | fn process_and_parameter_substitution_bodies_are_commands() { |
| 580 | assert!(contains("diff <(rm -rf /) b", "rm -rf /")); |
| 581 | assert!(contains("echo ${x:-$(rm -rf /)}", "rm -rf /")); |
| 582 | } |
| 583 | |
| 584 | #[test] |
| 585 | fn expansion_is_bounded() { |
| 586 | let deep = "$(".repeat(64) + "rm -rf /" + &")".repeat(64); |
| 587 | let targets = expand(&deep); |
| 588 | assert!(targets.len() <= MAX_COMMANDS); |
| 589 | } |
| 590 | |
| 591 | #[test] |
| 592 | fn grouping_is_a_command_boundary() { |
| 593 | assert!(contains("(rm -rf /)", "rm -rf /")); |
| 594 | assert!(contains("{ rm -rf /; }", "rm -rf /")); |
| 595 | assert!(contains("(cd /tmp && rm -rf /)", "rm -rf /")); |
| 596 | // Escaped and quoted parens are operands, not grouping. |
| 597 | assert!(contains( |
| 598 | "find . \\( -name a \\) -print", |
| 599 | "find . ( -name a ) -print" |
| 600 | )); |
| 601 | } |
| 602 | |
| 603 | #[test] |
| 604 | fn plain_command_expands_to_itself() { |
| 605 | assert_eq!(expand("git status -s"), vec!["git status -s".to_string()]); |
| 606 | } |
| 607 | } |
| 608 |