dre_core/
secrets.rs

1//! Secret masking. The value of every environment variable named `DRE_SECRET_*` is replaced by
2//! `*****` in everything DRE writes for people to read: the console, `logs/dre.log`, JSON events,
3//! `run_results.json` and the compiled SQL in `target/compiled/`. The SQL actually sent to the
4//! database is unchanged. `mask_secrets: false` in `dre_project.yml` turns masking off.
5//!
6//! JSON is redacted structurally, before it is serialized: serializing escapes `"`, `\` and
7//! control characters, so masking the finished text would miss a secret that contains them. Use
8//! [`to_json_pretty`] / [`to_json_line`] for every JSON surface, never `mask` on JSON text.
9//!
10//! Values shorter than 4 characters aren't masked: replacing every `a` or `12` in a log would
11//! make it unreadable, and a value that short isn't a secret anyway.
12
13use std::borrow::Cow;
14use std::sync::LazyLock;
15use std::sync::atomic::{AtomicBool, Ordering};
16
17pub const PREFIX: &str = "DRE_SECRET_";
18pub const MASK: &str = "*****";
19pub const MASKED_SOURCE_ERROR: &str =
20    "source error details omitted because the request contains a masked secret";
21const MIN_LEN: usize = 4;
22
23static ENABLED: AtomicBool = AtomicBool::new(true);
24
25fn eligible(value: &str) -> bool {
26    value.chars().count() >= MIN_LEN
27}
28
29/// Secret values, longest first so a secret containing another is masked whole.
30static SECRETS: LazyLock<Vec<String>> = LazyLock::new(|| {
31    let mut v: Vec<String> = std::env::vars()
32        .filter(|(k, v)| k.starts_with(PREFIX) && eligible(v))
33        .map(|(_, v)| v)
34        .collect();
35    v.sort_by_key(|s| std::cmp::Reverse(s.len()));
36    v.dedup();
37    v
38});
39
40pub fn set_enabled(on: bool) {
41    ENABLED.store(on, Ordering::Relaxed);
42}
43
44pub(crate) fn enabled() -> bool {
45    ENABLED.load(Ordering::Relaxed)
46}
47
48fn mask_with<'a>(s: &'a str, secrets: &[String]) -> Cow<'a, str> {
49    if !secrets.iter().any(|x| s.contains(x.as_str())) {
50        return Cow::Borrowed(s);
51    }
52    let mut out = s.to_string();
53    for x in secrets {
54        out = out.replace(x.as_str(), MASK);
55    }
56    Cow::Owned(out)
57}
58
59/// `s` with every secret value replaced by `*****`.
60pub fn mask(s: &str) -> Cow<'_, str> {
61    if !ENABLED.load(Ordering::Relaxed) {
62        return Cow::Borrowed(s);
63    }
64    mask_with(s, &SECRETS)
65}
66
67/// Whether masking is enabled and `s` contains a complete registered secret.
68pub fn contains_secret(s: &str) -> bool {
69    ENABLED.load(Ordering::Relaxed) && SECRETS.iter().any(|secret| s.contains(secret))
70}
71
72fn mask_source_error_with<'a>(error: &'a str, sensitive: bool, secrets: &[String]) -> Cow<'a, str> {
73    if sensitive {
74        Cow::Borrowed(MASKED_SOURCE_ERROR)
75    } else {
76        mask_with(error, secrets)
77    }
78}
79
80/// Mask a source error before it reaches logs or output. Source plugins can transform or truncate
81/// a request in their diagnostics, so exact replacement is not sufficient for a secret-bearing
82/// request. In that case the opaque detail is omitted instead.
83pub fn mask_source_error(error: &str, sensitive: bool) -> Cow<'_, str> {
84    if !ENABLED.load(Ordering::Relaxed) {
85        return Cow::Borrowed(error);
86    }
87    mask_source_error_with(error, sensitive, &SECRETS)
88}
89
90fn unique_masked_names_with(names: &[String], secrets: &[String]) -> Vec<String> {
91    use std::collections::BTreeSet;
92
93    let masked: Vec<String> = names
94        .iter()
95        .map(|name| mask_with(name, secrets).into_owned())
96        .collect();
97    if names == masked {
98        return names.to_vec();
99    }
100    let mut used = BTreeSet::new();
101    let mut output = vec![String::new(); names.len()];
102    let mut pending = Vec::new();
103
104    // Literal names keep their public identity and reserve every suffix they already occupy.
105    for (index, (original, protected)) in names.iter().zip(&masked).enumerate() {
106        if original == protected {
107            used.insert(original.clone());
108            output[index].clone_from(original);
109        } else {
110            pending.push((protected.clone(), original.clone(), index));
111        }
112    }
113
114    // Original names make the assignment stable when source ordering changes.
115    pending.sort();
116    for (base, _, index) in pending {
117        let mut candidate = base.clone();
118        let mut suffix = 2;
119        while !used.insert(candidate.clone()) {
120            candidate = format!("{base}#{suffix}");
121            suffix += 1;
122        }
123        output[index] = candidate;
124    }
125    output
126}
127
128fn redact_json_with(v: &mut serde_json::Value, secrets: &[String]) {
129    use serde_json::Value;
130    match v {
131        Value::String(s) => {
132            if let Cow::Owned(m) = mask_with(s, secrets) {
133                *s = m;
134            }
135        }
136        Value::Array(a) => a.iter_mut().for_each(|v| redact_json_with(v, secrets)),
137        Value::Object(o) => {
138            let entries = std::mem::take(o);
139            let keys: Vec<String> = entries.keys().cloned().collect();
140            let protected_keys = unique_masked_names_with(&keys, secrets);
141            for ((_, mut val), protected_key) in entries.into_iter().zip(protected_keys) {
142                redact_json_with(&mut val, secrets);
143                o.insert(protected_key, val);
144            }
145        }
146        _ => {}
147    }
148}
149
150/// `v` with every secret value replaced by `*****` in all strings and object keys. Colliding
151/// masked keys receive `#2`, `#3`, and so on rather than silently replacing another entry.
152pub fn redact_json(v: &mut serde_json::Value) {
153    if ENABLED.load(Ordering::Relaxed) {
154        redact_json_with(v, &SECRETS);
155    }
156}
157
158fn redacted<T: serde::Serialize>(v: &T) -> serde_json::Result<serde_json::Value> {
159    let mut v = serde_json::to_value(v)?;
160    redact_json(&mut v);
161    Ok(v)
162}
163
164/// Pretty JSON of `v` with secrets redacted first.
165pub fn to_json_pretty<T: serde::Serialize>(v: &T) -> serde_json::Result<String> {
166    serde_json::to_string_pretty(&redacted(v)?)
167}
168
169/// One-line JSON of `v` with secrets redacted first.
170pub fn to_json_line<T: serde::Serialize>(v: &T) -> serde_json::Result<String> {
171    serde_json::to_string(&redacted(v)?)
172}
173
174#[cfg(test)]
175mod tests {
176    use super::*;
177    use serde_json::json;
178
179    fn secrets(values: &[&str]) -> Vec<String> {
180        let mut values: Vec<String> = values.iter().map(|v| (*v).to_string()).collect();
181        values.sort_by_key(|s| std::cmp::Reverse(s.len()));
182        values
183    }
184
185    #[test]
186    fn redacts_nested_values_longest_first() {
187        let secrets = secrets(&["nested-secret", "nested-secret-and-more"]);
188        let mut value = json!({"items": ["nested-secret-and-more", {"value": "x nested-secret y"}]});
189        redact_json_with(&mut value, &secrets);
190        assert_eq!(value, json!({"items": ["*****", {"value": "x ***** y"}]}));
191    }
192
193    #[test]
194    fn preserves_entries_when_masked_keys_collide() {
195        let secrets = secrets(&["alpha-secret-key", "bravo-secret-key"]);
196        let mut value = json!({
197            "alpha-secret-key": 1,
198            "bravo-secret-key": 2,
199            "*****": 3,
200            "*****#2": 4,
201        });
202        redact_json_with(&mut value, &secrets);
203        assert_eq!(
204            value,
205            json!({
206                "*****": 3,
207                "*****#2": 4,
208                "*****#3": 1,
209                "*****#4": 2,
210            })
211        );
212    }
213
214    #[test]
215    fn masking_one_name_does_not_rename_duplicate_literal_names() {
216        let secrets = secrets(&["secret-column"]);
217        let names = ["a", "a", "secret-column"].map(str::to_string);
218        assert_eq!(unique_masked_names_with(&names, &secrets), ["a", "a", "*****"]);
219    }
220
221    #[test]
222    fn suppresses_transformed_source_errors_only_for_secret_requests() {
223        let secrets = secrets(&["long-secret-value-that-a-source-truncated"]);
224        let error = "LINE 1: select * from long-secret-value-that-a-source...";
225        assert_eq!(mask_source_error_with(error, true, &secrets), MASKED_SOURCE_ERROR);
226        assert_eq!(
227            mask_source_error_with("ordinary syntax error", false, &secrets),
228            "ordinary syntax error"
229        );
230    }
231
232    #[test]
233    fn minimum_length_counts_unicode_characters() {
234        assert!(!eligible("ééé"));
235        assert!(eligible("éééé"));
236    }
237}
dre_core/secrets.rs

dre_core/
secrets.rs
