podman-remote: prevent leaking secret into image

Prevents temp secrets leaking into image by moving it away from context
directory to parent builder directory. Builder directory automatically
gets cleaned up when we are done with the build.

Signed-off-by: Aditya Rajan <arajan@redhat.com>

pkg/api/handlers/compat/images_build.go

@@ -259,7 +259,19 @@ func BuildImage(w http.ResponseWriter, r *http.Request) {
 					arr := strings.SplitN(token, "=", 2)
 					if len(arr) > 1 {
 						if arr[0] == "src" {
-							modifiedSrc := fmt.Sprintf("src=%s", filepath.Join(contextDirectory, arr[1]))
+							/* move secret away from contextDir */
+							/* to make sure we dont accidentally commit temporary secrets to image*/
+							builderDirectory, _ := filepath.Split(contextDirectory)
+							// following path is outside build context
+							newSecretPath := filepath.Join(builderDirectory, arr[1])
+							oldSecretPath := filepath.Join(contextDirectory, arr[1])
+							err := os.Rename(oldSecretPath, newSecretPath)
+							if err != nil {
+								utils.BadRequest(w, "secrets", query.Secrets, err)
+								return
+							}
+
+							modifiedSrc := fmt.Sprintf("src=%s", newSecretPath)
 							modifiedOpt = append(modifiedOpt, modifiedSrc)
 						} else {
 							modifiedOpt = append(modifiedOpt, token)

test/e2e/build/Dockerfile.with-secret-verify-leak

@@ -0,0 +1,3 @@
+FROM alpine
+COPY * /
+RUN --mount=type=secret,id=mysecret cat /run/secrets/mysecret

test/e2e/build_test.go

@@ -82,6 +82,22 @@ var _ = Describe("Podman build", func() {
 		Expect(session).Should(Exit(0))
 	})
 
+	It("podman build with a secret from file and verify if secret file is not leaked into image", func() {
+		session := podmanTest.Podman([]string{"build", "-f", "build/Dockerfile.with-secret-verify-leak", "-t", "secret-test-leak", "--secret", "id=mysecret,src=build/secret.txt", "build/"})
+		session.WaitWithDefaultTimeout()
+		Expect(session).Should(Exit(0))
+		Expect(session.OutputToString()).To(ContainSubstring("somesecret"))
+
+		session = podmanTest.Podman([]string{"run", "--rm", "secret-test-leak", "ls"})
+		session.WaitWithDefaultTimeout()
+		Expect(session).Should(Exit(0))
+		Expect(session.OutputToString()).To(Not(ContainSubstring("podman-build-secret")))
+
+		session = podmanTest.Podman([]string{"rmi", "secret-test-leak"})
+		session.WaitWithDefaultTimeout()
+		Expect(session).Should(Exit(0))
+	})
+
 	It("podman build with logfile", func() {
 		logfile := filepath.Join(podmanTest.TempDir, "logfile")
 		session := podmanTest.Podman([]string{"build", "--pull-never", "--tag", "test", "--logfile", logfile, "build/basicalpine"})