audanye-sudo
464d571eb3
- Add internal/validate with control char rejection, ANSI stripping, URL query/fragment stripping, and terminal sanitization - Refactor output/sanitize.go to delegate to validate package - Update sanitize test to reflect ANSI escape stripping behavior
82 lines
2.8 KiB
Go
82 lines
2.8 KiB
Go
// Copyright 2026 Alibaba Group
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Package validate provides input sanitization and validation functions
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// to prevent injection attacks (control characters, CRLF, Unicode spoofing,
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// ANSI escape sequences) at the CLI boundary.
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package validate
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import (
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"fmt"
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"strings"
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)
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// RejectControlChars rejects C0 control characters (except \t and \n) and
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// dangerous Unicode characters from user input.
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//
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// Control characters cause subtle security issues: null bytes truncate strings
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// at the C layer, \r enables HTTP header injection via CRLF.
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// Dangerous Unicode characters allow visual spoofing (e.g. making "admin"
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// appear as a different string via Bidi overrides).
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func RejectControlChars(value, flagName string) error {
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for _, r := range value {
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if r != '\t' && r != '\n' && (r < 0x20 || r == 0x7f) {
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return fmt.Errorf("%s contains invalid control characters", flagName)
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}
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if isDangerousUnicode(r) {
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return fmt.Errorf("%s contains dangerous Unicode characters", flagName)
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}
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}
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return nil
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}
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// RejectCRLF rejects strings containing carriage return (\r) or line feed (\n).
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// These characters enable MIME/HTTP header injection and must never appear in
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// header values, filenames, or single-line parameters.
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func RejectCRLF(value, fieldName string) error {
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if strings.ContainsAny(value, "\r\n") {
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return fmt.Errorf("%s contains invalid line break characters", fieldName)
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}
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return nil
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}
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// StripQueryFragment removes any ?query or #fragment suffix from a URL path.
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// API parameters must go through structured flags, not embedded in the path,
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// to prevent parameter injection.
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func StripQueryFragment(path string) string {
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for i := 0; i < len(path); i++ {
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if path[i] == '?' || path[i] == '#' {
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return path[:i]
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}
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}
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return path
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}
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// isDangerousUnicode identifies Unicode code points used for visual spoofing.
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// These characters are invisible or alter text direction.
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func isDangerousUnicode(r rune) bool {
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switch {
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case r >= 0x200B && r <= 0x200D: // zero-width space/non-joiner/joiner
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return true
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case r == 0xFEFF: // BOM / ZWNBSP
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return true
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case r >= 0x202A && r <= 0x202E: // Bidi: LRE/RLE/PDF/LRO/RLO
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return true
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case r >= 0x2028 && r <= 0x2029: // line/paragraph separator
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return true
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case r >= 0x2066 && r <= 0x2069: // Bidi isolates: LRI/RLI/FSI/PDI
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return true
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}
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return false
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}
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