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JLLeitschuhJLLeitschuh
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Review feedback and improve temp dir vulnerable/safe code sugestion
1 parent 76964d5 commit 2048aed

3 files changed

Lines changed: 89 additions & 4 deletions

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‎java/ql/src/Security/CWE/CWE-200/TempDirUsageSafe.java‎

Lines changed: 84 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -1,3 +1,5 @@
1+
import java.io.File;
2+
import java.io.IOException;
13
import java.nio.file.Files;
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import java.nio.file.attribute.PosixFilePermission;
35
import java.nio.file.attribute.PosixFilePermissions;
@@ -9,11 +11,90 @@ void exampleSafe() throws IOException {
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1012
Path temp2 = Files.createTempDirectory("random-directory"); // GOOD: File has permissions `drwx------`
1113

12-
File tempDirChildFile = new File(System.getProperty("java.io.tmpdir"), "/child-create-file.txt");
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// Creating a temporary file with a non-randomly generated name
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File tempChildFile = new File(System.getProperty("java.io.tmpdir"), "/child-create-file.txt");
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// Warning: This will fail on windows as it doesn't support PosixFilePermissions.
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// See `exampleSafeWithWindowsSupportFile` if your code needs to support windows and unix-like systems.
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Files.createFile(
14-
tempDirChildFile.toPath(),
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tempDirChild.toPath(),
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tempChildFile.toPath(),
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PosixFilePermissions.asFileAttribute(EnumSet.of(PosixFilePermission.OWNER_READ, PosixFilePermission.OWNER_WRITE))
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); // GOOD: Good has permissions `-rw-------`
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}
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/*
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* An example of a safe use of createFile or createDirectory if your code must support windows and unix-like systems.
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*/
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void exampleSafeWithWindowsSupportFile() {
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// Creating a temporary file with a non-randomly generated name
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File tempChildFile = new File(System.getProperty("java.io.tmpdir"), "/child-create-file.txt");
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createTempFile(tempChildFile.toPath()); // GOOD: Good has permissions `-rw-------`
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}
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static void createTempFile(Path tempDir) {
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try {
35+
if (tempDirChild.getFileSystem().supportedFileAttributeViews().contains("posix")) {
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// Explicit permissions setting is only required on unix-like systems because
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// the temporary directory is shared between all users.
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// This is not necessary on Windows, each user has their own temp directory
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final EnumSet<PosixFilePermission> posixFilePermissions =
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EnumSet.of(
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PosixFilePermission.OWNER_READ,
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PosixFilePermission.OWNER_WRITE
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);
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if (!Files.exists(tempDirChild)) {
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Files.createFile(
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tempDirChild,
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PosixFilePermissions.asFileAttribute(posixFilePermissions)
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); // GOOD: Directory has permissions `-rw-------`
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} else {
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Files.setPosixFilePermissions(
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tempDirChild,
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posixFilePermissions
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); // GOOD: Good has permissions `-rw-------`, or will throw an exception if this fails
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}
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} else if (!Files.exists(tempDirChild)) {
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// On Windows, we still need to create the directory, when it doesn't already exist.
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Files.createDirectory(tempDirChild); // GOOD: Windows doesn't share the temp directory between users
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}
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} catch (IOException exception) {
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throw new UncheckedIOException("Failed to create temp file", exception);
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}
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}
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void exampleSafeWithWindowsSupportDirectory() {
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File tempDirChildDir = new File(System.getProperty("java.io.tmpdir"), "/child-dir");
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createTempDirectories(tempDirChildDir.toPath()); // GOOD: Directory has permissions `drwx------`
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}
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static void createTempDirectories(Path tempDirChild) {
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try {
71+
if (tempDirChild.getFileSystem().supportedFileAttributeViews().contains("posix")) {
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// Explicit permissions setting is only required on unix-like systems because
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// the temporary directory is shared between all users.
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// This is not necessary on Windows, each user has their own temp directory
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final EnumSet<PosixFilePermission> posixFilePermissions =
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EnumSet.of(
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PosixFilePermission.OWNER_READ,
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PosixFilePermission.OWNER_WRITE,
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PosixFilePermission.OWNER_EXECUTE
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);
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if (!Files.exists(tempDirChild)) {
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Files.createDirectories(
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tempDirChild,
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PosixFilePermissions.asFileAttribute(posixFilePermissions)
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); // GOOD: Directory has permissions `drwx------`
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} else {
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Files.setPosixFilePermissions(
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tempDirChild,
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posixFilePermissions
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); // GOOD: Good has permissions `drwx------`, or will throw an exception if this fails
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}
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} else if (!Files.exists(tempDirChild)) {
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// On Windows, we still need to create the directory, when it doesn't already exist.
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Files.createDirectories(tempDirChild); // GOOD: Windows doesn't share the temp directory between users
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}
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} catch (IOException exception) {
97+
throw new UncheckedIOException("Failed to create temp dir", exception);
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}
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}
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}

‎java/ql/src/Security/CWE/CWE-200/TempDirUsageVulnerable.java‎

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -15,5 +15,9 @@ void exampleVulnerable() {
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File tempDirChildFile = new File(System.getProperty("java.io.tmpdir"), "/child-create-file.txt");
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Files.createFile(tempDirChildFile.toPath()); // BAD: File has permissions `-rw-r--r--`
18+
19+
File tempDirChildDir = new File(System.getProperty("java.io.tmpdir"), "/child-dir");
20+
tempDirChildDir.mkdir(); // BAD: Directory has permissions `drwxr-xr-x`
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Files.createDirectory(tempDirChildDir.toPath()); // BAD: Directory has permissions `drwxr-xr-x`
1822
}
1923
}

‎java/ql/src/change-notes/2022-02-04-local-temp-file-or-directory-information-disclosure.md‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1,6 +1,6 @@
11
---
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category: newQuery
33
---
4-
* A new query titled "Temporary directory Local information disclosure" (`java/local-temp-file-or-directory-information-disclosure`) has been added.
4+
* A new query titled "Local information disclosure in a temporary directory" (`java/local-temp-file-or-directory-information-disclosure`) has been added.
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This query finds uses of APIs that leak potentially sensitive information to other local users via the system temporary directory.
66
This query was originally [submitted as query by @JLLeitschuh](https://github.com/github/codeql/pull/4388).

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