libpod: create /etc/passwd if missing

create the /etc/passwd and /etc/group files if they are missing in the
image.

Closes: https://github.com/containers/podman/issues/14966

Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>

2 files changed, 8 insertions, 40 deletions

diff --git a/libpod/container_internal_linux.go b/libpod/container_internal_linux.go
index 46e525add..a131ab367 100644
--- a/libpod/container_internal_linux.go
+++ b/libpod/container_internal_linux.go
@@ -2886,23 +2886,6 @@ func (c *Container) generatePasswdAndGroup() (string, string, error) {
 		}
 	}
 
-	// Next, check if the container even has a /etc/passwd or /etc/group.
-	// If it doesn't we don't want to create them ourselves.
-	if needPasswd {
-		exists, err := c.checkFileExistsInRootfs("/etc/passwd")
-		if err != nil {
-			return "", "", err
-		}
-		needPasswd = exists
-	}
-	if needGroup {
-		exists, err := c.checkFileExistsInRootfs("/etc/group")
-		if err != nil {
-			return "", "", err
-		}
-		needGroup = exists
-	}
-
 	// If we don't need a /etc/passwd or /etc/group at this point we can
 	// just return.
 	if !needPasswd && !needGroup {
@@ -2947,7 +2930,7 @@ func (c *Container) generatePasswdAndGroup() (string, string, error) {
 				return "", "", fmt.Errorf("error looking up location of container %s /etc/passwd: %w", c.ID(), err)
 			}
 
-			f, err := os.OpenFile(containerPasswd, os.O_APPEND|os.O_WRONLY, 0600)
+			f, err := os.OpenFile(containerPasswd, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0600)
 			if err != nil {
 				return "", "", fmt.Errorf("container %s: %w", c.ID(), err)
 			}
@@ -2993,7 +2976,7 @@ func (c *Container) generatePasswdAndGroup() (string, string, error) {
 				return "", "", fmt.Errorf("error looking up location of container %s /etc/group: %w", c.ID(), err)
 			}
 
-			f, err := os.OpenFile(containerGroup, os.O_APPEND|os.O_WRONLY, 0600)
+			f, err := os.OpenFile(containerGroup, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0600)
 			if err != nil {
 				return "", "", fmt.Errorf("container %s: %w", c.ID(), err)
 			}
@@ -3112,26 +3095,6 @@ func (c *Container) cleanupOverlayMounts() error {
 	return overlay.CleanupContent(c.config.StaticDir)
 }
 
-// Check if a file exists at the given path in the container's root filesystem.
-// Container must already be mounted for this to be used.
-func (c *Container) checkFileExistsInRootfs(file string) (bool, error) {
-	checkPath, err := securejoin.SecureJoin(c.state.Mountpoint, file)
-	if err != nil {
-		return false, fmt.Errorf("cannot create path to container %s file %q: %w", c.ID(), file, err)
-	}
-	stat, err := os.Stat(checkPath)
-	if err != nil {
-		if os.IsNotExist(err) {
-			return false, nil
-		}
-		return false, fmt.Errorf("container %s: %w", c.ID(), err)
-	}
-	if stat.IsDir() {
-		return false, nil
-	}
-	return true, nil
-}
-
 // Creates and mounts an empty dir to mount secrets into, if it does not already exist
 func (c *Container) createSecretMountDir() error {
 	src := filepath.Join(c.state.RunDir, "/run/secrets")
diff --git a/test/e2e/run_passwd_test.go b/test/e2e/run_passwd_test.go
index 411e12218..20a6ee3b1 100644
--- a/test/e2e/run_passwd_test.go
+++ b/test/e2e/run_passwd_test.go
@@ -66,10 +66,15 @@ RUN rm -f /etc/passwd /etc/shadow /etc/group
 USER 1000`, ALPINE)
 		imgName := "testimg"
 		podmanTest.BuildImage(dockerfile, imgName, "false")
-		session := podmanTest.Podman([]string{"run", "--rm", imgName, "ls", "/etc/"})
+		session := podmanTest.Podman([]string{"run", "--passwd=false", "--rm", imgName, "ls", "/etc/"})
 		session.WaitWithDefaultTimeout()
 		Expect(session).Should(Exit(0))
 		Expect(session.OutputToString()).To(Not(ContainSubstring("passwd")))
+
+		// test that the /etc/passwd file is created
+		session = podmanTest.Podman([]string{"run", "--rm", "--user", "0:0", imgName, "ls", "/etc/passwd"})
+		session.WaitWithDefaultTimeout()
+		Expect(session).Should(Exit(0))
 	})
 
 	It("podman run with no user specified does not change --group specified", func() {