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fix lack of escaping of filename in Content-Disposition (#3556)
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* fix lack of escaping of filename in Content-Disposition

* add test for Content-Disposition filename escaping process

* fix filename escape bypass problem
fix backslashes before backquotes were not properly escaped problem.
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motoyasu-saburi authored May 29, 2023
1 parent 9f5ecd4 commit 2d4bbec
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Showing 2 changed files with 21 additions and 1 deletion.
8 changes: 7 additions & 1 deletion context.go
Original file line number Diff line number Diff line change
Expand Up @@ -1052,11 +1052,17 @@ func (c *Context) FileFromFS(filepath string, fs http.FileSystem) {
http.FileServer(fs).ServeHTTP(c.Writer, c.Request)
}

var quoteEscaper = strings.NewReplacer("\\", "\\\\", `"`, "\\\"")

func escapeQuotes(s string) string {
return quoteEscaper.Replace(s)
}

// FileAttachment writes the specified file into the body stream in an efficient way
// On the client side, the file will typically be downloaded with the given filename
func (c *Context) FileAttachment(filepath, filename string) {
if isASCII(filename) {
c.Writer.Header().Set("Content-Disposition", `attachment; filename="`+filename+`"`)
c.Writer.Header().Set("Content-Disposition", `attachment; filename="`+escapeQuotes(filename)+`"`)
} else {
c.Writer.Header().Set("Content-Disposition", `attachment; filename*=UTF-8''`+url.QueryEscape(filename))
}
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14 changes: 14 additions & 0 deletions context_test.go
Original file line number Diff line number Diff line change
Expand Up @@ -1032,6 +1032,20 @@ func TestContextRenderAttachment(t *testing.T) {
assert.Equal(t, fmt.Sprintf("attachment; filename=\"%s\"", newFilename), w.Header().Get("Content-Disposition"))
}

func TestContextRenderAndEscapeAttachment(t *testing.T) {
w := httptest.NewRecorder()
c, _ := CreateTestContext(w)
maliciousFilename := "tampering_field.sh\"; \\\"; dummy=.go"
actualEscapedResponseFilename := "tampering_field.sh\\\"; \\\\\\\"; dummy=.go"

c.Request, _ = http.NewRequest("GET", "/", nil)
c.FileAttachment("./gin.go", maliciousFilename)

assert.Equal(t, 200, w.Code)
assert.Contains(t, w.Body.String(), "func New() *Engine {")
assert.Equal(t, fmt.Sprintf("attachment; filename=\"%s\"", actualEscapedResponseFilename), w.Header().Get("Content-Disposition"))
}

func TestContextRenderUTF8Attachment(t *testing.T) {
w := httptest.NewRecorder()
c, _ := CreateTestContext(w)
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