seccomp: allow specifying a custom profile with --privileged

`--privileged --security-opt seccomp=<CUSTOM.json>` was ignoring
`<CUSTOM.json>`.

Fix issue 47499

Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>

daemon/seccomp_linux.go

@@ -22,7 +22,11 @@ func WithSeccomp(daemon *Daemon, c *container.Container) coci.SpecOpts {
 			return nil
 		}
 		if c.HostConfig.Privileged {
-			return nil
+			var err error
+			if c.SeccompProfile != "" {
+				s.Linux.Seccomp, err = seccomp.LoadProfile(c.SeccompProfile, s)
+			}
+			return err
 		}
 		if !daemon.RawSysInfo().Seccomp {
 			if c.SeccompProfile != "" && c.SeccompProfile != dconfig.SeccompProfileDefault {

daemon/seccomp_linux_test.go

@@ -40,7 +40,9 @@ func TestWithSeccomp(t *testing.T) {
 			outSpec: oci.DefaultLinuxSpec(),
 		},
 		{
-			comment: "privileged container w/ custom profile runs unconfined",
+			// Prior to Docker v27, it had resulted in unconfined.
+			// https://github.com/moby/moby/pull/47500
+			comment: "privileged container w/ custom profile",
 			daemon: &Daemon{
 				sysInfo: &sysinfo.SysInfo{Seccomp: true},
 			},
@@ -50,8 +52,15 @@ func TestWithSeccomp(t *testing.T) {
 					Privileged: true,
 				},
 			},
-			inSpec:  oci.DefaultLinuxSpec(),
-			outSpec: oci.DefaultLinuxSpec(),
+			inSpec: oci.DefaultLinuxSpec(),
+			outSpec: func() coci.Spec {
+				s := oci.DefaultLinuxSpec()
+				profile := &specs.LinuxSeccomp{
+					DefaultAction: specs.LinuxSeccompAction("SCMP_ACT_LOG"),
+				}
+				s.Linux.Seccomp = profile
+				return s
+			}(),
 		},
 		{
 			comment: "privileged container w/ default runs unconfined",

integration/container/run_linux_test.go

@@ -353,6 +353,51 @@ func TestWorkingDirNormalization(t *testing.T) {
 
 			assert.Check(t, is.Equal(inspect.Config.WorkingDir, "/tmp"))
 		})
+	}
+}
+
+func TestSeccomp(t *testing.T) {
+	skip.If(t, testEnv.DaemonInfo.OSType != "linux")
+
+	ctx := setupTest(t)
+	apiClient := testEnv.APIClient()
 
+	const confined = `{
+ "defaultAction": "SCMP_ACT_ALLOW",
+ "syscalls": [ { "names": [ "chown" ], "action": "SCMP_ACT_ERRNO" } ]
+}
+`
+	type testCase struct {
+		ops              []func(*container.TestContainerConfig)
+		expectedExitCode int
+	}
+	testCases := []testCase{
+		{
+			ops:              nil,
+			expectedExitCode: 0,
+		},
+		{
+			ops:              []func(*container.TestContainerConfig){container.WithPrivileged(true)},
+			expectedExitCode: 0,
+		},
+		{
+			ops:              []func(*container.TestContainerConfig){container.WithSecurityOpt("seccomp=" + confined)},
+			expectedExitCode: 1,
+		},
+		{
+			// A custom profile should be still enabled, even when --privileged is set
+			// https://github.com/moby/moby/issues/47499
+			ops:              []func(*container.TestContainerConfig){container.WithPrivileged(true), container.WithSecurityOpt("seccomp=" + confined)},
+			expectedExitCode: 1,
+		},
+	}
+	for _, tc := range testCases {
+		cID := container.Run(ctx, t, apiClient, tc.ops...)
+		res, err := container.Exec(ctx, apiClient, cID, []string{"chown", "42", "/bin/true"})
+		assert.NilError(t, err)
+		assert.Equal(t, tc.expectedExitCode, res.ExitCode)
+		if tc.expectedExitCode != 0 {
+			assert.Check(t, is.Contains(res.Stderr(), "Operation not permitted"))
+		}
 	}
 }