Restrict editable files by number of characters (#20462)

GitOrigin-RevId: fad0c14444a9d382ad05c14921118ef3883ede79

services/web/app/src/Features/Uploads/FileTypeManager.js

@@ -15,7 +15,7 @@ const FileTypeManager = {
   TEXT_EXTENSIONS: new Set(Settings.textExtensions.map(ext => `.${ext}`)),
   EDITABLE_FILENAMES: Settings.editableFilenames,
 
-  MAX_TEXT_FILE_SIZE: 1 * 1024 * 1024, // 1 MB
+  MAX_TEXT_FILE_SIZE: 3 * Settings.max_doc_length, // allow 3 bytes for every character
 
   isDirectory(path, callback) {
     fs.stat(path, (error, stats) => {
@@ -61,6 +61,9 @@ const FileTypeManager = {
         }
         const encoding = _detectEncoding(bytes)
         const text = bytes.toString(encoding)
+        if (text.length >= Settings.max_doc_length) {
+          return callback(null, { binary: true }) // Treat large text file as binary
+        }
         // For compatibility with the history service, only accept valid utf8 with no
         // nulls or non-BMP characters as text, eveything else is binary.
         if (text.includes('\x00')) {
@@ -75,28 +78,6 @@ const FileTypeManager = {
     })
   },
 
-  getStrictTypeFromContent(name, contents) {
-    const basename = Path.basename(name)
-    const isText = _isTextFilename(basename)
-
-    if (!isText) {
-      return false
-    }
-    if (
-      Buffer.byteLength(contents, 'utf8') > FileTypeManager.MAX_TEXT_FILE_SIZE
-    ) {
-      return false
-    }
-    if (contents.indexOf('\x00') !== -1) {
-      return false
-    }
-    if (/[\uD800-\uDFFF]/.test(contents)) {
-      // non-BMP characters (high and low surrogate characters)
-      return false
-    }
-    return true
-  },
-
   // FIXME: we can convert this to a synchronous function if we want to
   shouldIgnore(path, callback) {
     // use minimatch file matching to check if the path should be ignored

services/web/test/unit/src/Uploads/FileTypeManagerTests.js

@@ -38,6 +38,18 @@ describe('FileTypeManager', function () {
     this.fs.readFile
       .withArgs('utf8-control-chars.tex')
       .yields(null, Buffer.from(`${fileContents}\x0c${fileContents}`))
+    this.fs.readFile
+      .withArgs('text-short.tex')
+      .yields(null, Buffer.from('a'.repeat(0.5 * 1024 * 1024), 'utf-8'))
+    this.fs.readFile
+      .withArgs('text-smaller.tex')
+      .yields(null, Buffer.from('a'.repeat(2 * 1024 * 1024 - 1), 'utf-8'))
+    this.fs.readFile
+      .withArgs('text-exact.tex')
+      .yields(null, Buffer.from('a'.repeat(2 * 1024 * 1024), 'utf-8'))
+    this.fs.readFile
+      .withArgs('text-long.tex')
+      .yields(null, Buffer.from('a'.repeat(3 * 1024 * 1024), 'utf-8'))
     this.callback = sinon.stub()
     this.DocumentHelper = { getEncodingFromTexContent: sinon.stub() }
     this.FileTypeManager = SandboxedModule.require(modulePath, {
@@ -117,8 +129,72 @@ describe('FileTypeManager', function () {
         })
       })
 
+      it('should not classify short text files as binary', function (done) {
+        this.stats.size = 2 * 1024 * 1024 // 2MB
+        this.FileTypeManager.getType(
+          '/file.tex',
+          'text-short.tex',
+          null,
+          (err, { binary }) => {
+            if (err) {
+              return done(err)
+            }
+            binary.should.equal(false)
+            done()
+          }
+        )
+      })
+
+      it('should not classify text files just under the size limit as binary', function (done) {
+        this.stats.size = 2 * 1024 * 1024 // 2MB
+        this.FileTypeManager.getType(
+          '/file.tex',
+          'text-smaller.tex',
+          null,
+          (err, { binary }) => {
+            if (err) {
+              return done(err)
+            }
+            binary.should.equal(false)
+            done()
+          }
+        )
+      })
+
+      it('should classify text files at the size limit as binary', function (done) {
+        this.stats.size = 2 * 1024 * 1024 // 2MB
+        this.FileTypeManager.getType(
+          '/file.tex',
+          'text-exact.tex',
+          null,
+          (err, { binary }) => {
+            if (err) {
+              return done(err)
+            }
+            binary.should.equal(true)
+            done()
+          }
+        )
+      })
+
+      it('should classify long text files as binary', function (done) {
+        this.stats.size = 2 * 1024 * 1024 // 2MB
+        this.FileTypeManager.getType(
+          '/file.tex',
+          'text-long.tex',
+          null,
+          (err, { binary }) => {
+            if (err) {
+              return done(err)
+            }
+            binary.should.equal(true)
+            done()
+          }
+        )
+      })
+
       it('should classify large text files as binary', function (done) {
-        this.stats.size = 2 * 1024 * 1024 // 2Mb
+        this.stats.size = 8 * 1024 * 1024 // 8MB
         this.FileTypeManager.getType(
           '/file.tex',
           'utf8.tex',
@@ -134,7 +210,7 @@ describe('FileTypeManager', function () {
       })
 
       it('should not try to determine the encoding of large files', function (done) {
-        this.stats.size = 2 * 1024 * 1024 // 2Mb
+        this.stats.size = 8 * 1024 * 1024 // 8MB
         this.FileTypeManager.getType('/file.tex', 'utf8.tex', null, err => {
           if (err) {
             return done(err)