From bce8f851c1e891aa6159e61c56ccd712b60c31b7 Mon Sep 17 00:00:00 2001 From: Giuseppe Scrivano Date: Mon, 2 Nov 2020 14:26:30 +0100 Subject: specgen: add support for ambient capabilities if the kernel supports ambient capabilities (Linux 4.3+), also set them when running with euid != 0. This is different that what Moby does, as ambient capabilities are never set. Signed-off-by: Giuseppe Scrivano --- pkg/specgen/generate/config_linux.go | 5 +++++ pkg/specgen/generate/security.go | 6 ++++++ test/e2e/run_test.go | 15 +++++++++++++++ 3 files changed, 26 insertions(+) diff --git a/pkg/specgen/generate/config_linux.go b/pkg/specgen/generate/config_linux.go index fcb7641d2..2d40dba8f 100644 --- a/pkg/specgen/generate/config_linux.go +++ b/pkg/specgen/generate/config_linux.go @@ -350,3 +350,8 @@ func deviceFromPath(path string) (*spec.LinuxDevice, error) { Minor: int64(unix.Minor(devNumber)), }, nil } + +func supportAmbientCapabilities() bool { + err := unix.Prctl(unix.PR_CAP_AMBIENT, unix.PR_CAP_AMBIENT_IS_SET, 0, 0, 0) + return err == nil +} diff --git a/pkg/specgen/generate/security.go b/pkg/specgen/generate/security.go index d17cd4a9a..8a9fd7a41 100644 --- a/pkg/specgen/generate/security.go +++ b/pkg/specgen/generate/security.go @@ -145,6 +145,12 @@ func securityConfigureGenerator(s *specgen.SpecGenerator, g *generate.Generator, } configSpec.Process.Capabilities.Effective = userCaps configSpec.Process.Capabilities.Permitted = userCaps + + // Ambient capabilities were added to Linux 4.3. Set ambient + // capabilities only when the kernel supports them. + if supportAmbientCapabilities() { + configSpec.Process.Capabilities.Ambient = userCaps + } } g.SetProcessNoNewPrivileges(s.NoNewPrivileges) diff --git a/test/e2e/run_test.go b/test/e2e/run_test.go index e6bba9f67..010d7aaae 100644 --- a/test/e2e/run_test.go +++ b/test/e2e/run_test.go @@ -315,6 +315,21 @@ var _ = Describe("Podman run", func() { session.WaitWithDefaultTimeout() Expect(session.ExitCode()).To(Equal(0)) Expect(session.OutputToString()).To(ContainSubstring("00000000a80425fb")) + + session = podmanTest.Podman([]string{"run", "--user=1000:1000", "--cap-add=DAC_OVERRIDE", "--rm", ALPINE, "grep", "CapAmb", "/proc/self/status"}) + session.WaitWithDefaultTimeout() + Expect(session.ExitCode()).To(Equal(0)) + Expect(session.OutputToString()).To(ContainSubstring("0000000000000002")) + + session = podmanTest.Podman([]string{"run", "--user=1000:1000", "--rm", ALPINE, "grep", "CapAmb", "/proc/self/status"}) + session.WaitWithDefaultTimeout() + Expect(session.ExitCode()).To(Equal(0)) + Expect(session.OutputToString()).To(ContainSubstring("0000000000000000")) + + session = podmanTest.Podman([]string{"run", "--user=0", "--cap-add=DAC_OVERRIDE", "--rm", ALPINE, "grep", "CapAmb", "/proc/self/status"}) + session.WaitWithDefaultTimeout() + Expect(session.ExitCode()).To(Equal(0)) + Expect(session.OutputToString()).To(ContainSubstring("0000000000000000")) }) It("podman run user capabilities test with image", func() { -- cgit v1.2.3-54-g00ecf From 6a9442909869a949d8930b24f9c0021022528333 Mon Sep 17 00:00:00 2001 From: Giuseppe Scrivano Date: Mon, 2 Nov 2020 14:39:00 +0100 Subject: specgen: fix check for root user if the username is specified in the USER:GROUP form, make sure we only check for USER. Signed-off-by: Giuseppe Scrivano --- pkg/specgen/generate/security.go | 4 +++- test/e2e/run_test.go | 5 +++++ 2 files changed, 8 insertions(+), 1 deletion(-) diff --git a/pkg/specgen/generate/security.go b/pkg/specgen/generate/security.go index 8a9fd7a41..be6555195 100644 --- a/pkg/specgen/generate/security.go +++ b/pkg/specgen/generate/security.go @@ -135,7 +135,9 @@ func securityConfigureGenerator(s *specgen.SpecGenerator, g *generate.Generator, configSpec.Process.Capabilities.Bounding = caplist configSpec.Process.Capabilities.Inheritable = caplist - if s.User == "" || s.User == "root" || s.User == "0" { + user := strings.Split(s.User, ":")[0] + + if user == "" || user == "root" || user == "0" { configSpec.Process.Capabilities.Effective = caplist configSpec.Process.Capabilities.Permitted = caplist } else { diff --git a/test/e2e/run_test.go b/test/e2e/run_test.go index 010d7aaae..9f86f43aa 100644 --- a/test/e2e/run_test.go +++ b/test/e2e/run_test.go @@ -330,6 +330,11 @@ var _ = Describe("Podman run", func() { session.WaitWithDefaultTimeout() Expect(session.ExitCode()).To(Equal(0)) Expect(session.OutputToString()).To(ContainSubstring("0000000000000000")) + + session = podmanTest.Podman([]string{"run", "--user=0:0", "--cap-add=DAC_OVERRIDE", "--rm", ALPINE, "grep", "CapAmb", "/proc/self/status"}) + session.WaitWithDefaultTimeout() + Expect(session.ExitCode()).To(Equal(0)) + Expect(session.OutputToString()).To(ContainSubstring("0000000000000000")) }) It("podman run user capabilities test with image", func() { -- cgit v1.2.3-54-g00ecf From afa4ec0db01b620be540e72e25fc86092e2fa303 Mon Sep 17 00:00:00 2001 From: Giuseppe Scrivano Date: Mon, 2 Nov 2020 14:45:54 +0100 Subject: specgen: keep capabilities with --userns=keep-id if --userns=keep-id is specified and not --user is specified, take the unprivileged capabilities code path so that ambient capabilities are honored in the container. Signed-off-by: Giuseppe Scrivano --- pkg/specgen/generate/security.go | 2 +- test/e2e/run_test.go | 13 +++++++++++++ 2 files changed, 14 insertions(+), 1 deletion(-) diff --git a/pkg/specgen/generate/security.go b/pkg/specgen/generate/security.go index be6555195..dee140282 100644 --- a/pkg/specgen/generate/security.go +++ b/pkg/specgen/generate/security.go @@ -137,7 +137,7 @@ func securityConfigureGenerator(s *specgen.SpecGenerator, g *generate.Generator, user := strings.Split(s.User, ":")[0] - if user == "" || user == "root" || user == "0" { + if (user == "" && s.UserNS.NSMode != specgen.KeepID) || user == "root" || user == "0" { configSpec.Process.Capabilities.Effective = caplist configSpec.Process.Capabilities.Permitted = caplist } else { diff --git a/test/e2e/run_test.go b/test/e2e/run_test.go index 9f86f43aa..deb4419af 100644 --- a/test/e2e/run_test.go +++ b/test/e2e/run_test.go @@ -335,6 +335,19 @@ var _ = Describe("Podman run", func() { session.WaitWithDefaultTimeout() Expect(session.ExitCode()).To(Equal(0)) Expect(session.OutputToString()).To(ContainSubstring("0000000000000000")) + + if os.Geteuid() > 0 { + if os.Getenv("SKIP_USERNS") != "" { + Skip("Skip userns tests.") + } + if _, err := os.Stat("/proc/self/uid_map"); err != nil { + Skip("User namespaces not supported.") + } + session = podmanTest.Podman([]string{"run", "--userns=keep-id", "--cap-add=DAC_OVERRIDE", "--rm", ALPINE, "grep", "CapAmb", "/proc/self/status"}) + session.WaitWithDefaultTimeout() + Expect(session.ExitCode()).To(Equal(0)) + Expect(session.OutputToString()).To(ContainSubstring("0000000000000002")) + } }) It("podman run user capabilities test with image", func() { -- cgit v1.2.3-54-g00ecf