2020-07-10 23:02:12

by Kees Cook

Subject: [PATCH for-next/seccomp v2 1/2] selftests/seccomp: Add SKIPs for failed unshare()

Running the seccomp tests as a regular user shouldn't just fail tests
that require CAP_SYS_ADMIN (for getting a PID namespace). Instead,
detect those cases and SKIP them. Additionally, gracefully SKIP missing
CONFIG_USER_NS (and add to "config" since we'd prefer to actually test
this case).

Signed-off-by: Kees Cook <[email protected]>
---
tools/testing/selftests/seccomp/config | 1 +
tools/testing/selftests/seccomp/seccomp_bpf.c | 10 ++++++++--
2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/seccomp/config b/tools/testing/selftests/seccomp/config
index db1e11b08c8a..64c19d8eba79 100644
--- a/tools/testing/selftests/seccomp/config
+++ b/tools/testing/selftests/seccomp/config
@@ -1,2 +1,3 @@
CONFIG_SECCOMP=y
CONFIG_SECCOMP_FILTER=y
+CONFIG_USER_NS=y
diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c
index c0aa46ce14f6..14b038361549 100644
--- a/tools/testing/selftests/seccomp/seccomp_bpf.c
+++ b/tools/testing/selftests/seccomp/seccomp_bpf.c
@@ -3439,7 +3439,10 @@ TEST(user_notification_child_pid_ns)
struct seccomp_notif req = {};
struct seccomp_notif_resp resp = {};

- ASSERT_EQ(unshare(CLONE_NEWUSER | CLONE_NEWPID), 0);
+ ASSERT_EQ(unshare(CLONE_NEWUSER | CLONE_NEWPID), 0) {
+ if (errno == EINVAL)
+ SKIP(return, "kernel missing CLONE_NEWUSER support");
+ };

listener = user_trap_syscall(__NR_getppid,
SECCOMP_FILTER_FLAG_NEW_LISTENER);
@@ -3504,7 +3507,10 @@ TEST(user_notification_sibling_pid_ns)
}

/* Create the sibling ns, and sibling in it. */
- ASSERT_EQ(unshare(CLONE_NEWPID), 0);
+ ASSERT_EQ(unshare(CLONE_NEWPID), 0) {
+ if (errno == EPERM)
+ SKIP(return, "CLONE_NEWPID requires CAP_SYS_ADMIN");
+ }
ASSERT_EQ(errno, 0);

pid2 = fork();
--
2.25.1

2020-07-11 16:03:56

by Christian Brauner

Subject: Re: [PATCH for-next/seccomp v2 1/2] selftests/seccomp: Add SKIPs for failed unshare()

On Fri, Jul 10, 2020 at 04:01:06PM -0700, Kees Cook wrote:
> Running the seccomp tests as a regular user shouldn't just fail tests
> that require CAP_SYS_ADMIN (for getting a PID namespace). Instead,
> detect those cases and SKIP them. Additionally, gracefully SKIP missing
> CONFIG_USER_NS (and add to "config" since we'd prefer to actually test
> this case).
>
> Signed-off-by: Kees Cook <[email protected]>
> ---

Just a comment, otherwise:
Acked-by: Christian Brauner <[email protected]>

> tools/testing/selftests/seccomp/config | 1 +
> tools/testing/selftests/seccomp/seccomp_bpf.c | 10 ++++++++--
> 2 files changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/tools/testing/selftests/seccomp/config b/tools/testing/selftests/seccomp/config
> index db1e11b08c8a..64c19d8eba79 100644
> --- a/tools/testing/selftests/seccomp/config
> +++ b/tools/testing/selftests/seccomp/config
> @@ -1,2 +1,3 @@
> CONFIG_SECCOMP=y
> CONFIG_SECCOMP_FILTER=y
> +CONFIG_USER_NS=y
> diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c
> index c0aa46ce14f6..14b038361549 100644
> --- a/tools/testing/selftests/seccomp/seccomp_bpf.c
> +++ b/tools/testing/selftests/seccomp/seccomp_bpf.c
> @@ -3439,7 +3439,10 @@ TEST(user_notification_child_pid_ns)
> struct seccomp_notif req = {};
> struct seccomp_notif_resp resp = {};
>
> - ASSERT_EQ(unshare(CLONE_NEWUSER | CLONE_NEWPID), 0);
> + ASSERT_EQ(unshare(CLONE_NEWUSER | CLONE_NEWPID), 0) {
> + if (errno == EINVAL)
> + SKIP(return, "kernel missing CLONE_NEWUSER support");

That would be either CLONE_NEWUSER or CLONE_NEWPID, right? :)
Maybe just do:
"kernel misses necessary namespace support"


> + };
>
> listener = user_trap_syscall(__NR_getppid,
> SECCOMP_FILTER_FLAG_NEW_LISTENER);
> @@ -3504,7 +3507,10 @@ TEST(user_notification_sibling_pid_ns)
> }
>
> /* Create the sibling ns, and sibling in it. */
> - ASSERT_EQ(unshare(CLONE_NEWPID), 0);
> + ASSERT_EQ(unshare(CLONE_NEWPID), 0) {
> + if (errno == EPERM)
> + SKIP(return, "CLONE_NEWPID requires CAP_SYS_ADMIN");
> + }
> ASSERT_EQ(errno, 0);
>
> pid2 = fork();
> --
> 2.25.1
>

2020-07-11 16:06:59

by Tycho Andersen

Subject: Re: [PATCH for-next/seccomp v2 1/2] selftests/seccomp: Add SKIPs for failed unshare()

On Fri, Jul 10, 2020 at 04:01:06PM -0700, Kees Cook wrote:
> Running the seccomp tests as a regular user shouldn't just fail tests
> that require CAP_SYS_ADMIN (for getting a PID namespace). Instead,
> detect those cases and SKIP them. Additionally, gracefully SKIP missing
> CONFIG_USER_NS (and add to "config" since we'd prefer to actually test
> this case).
>
> Signed-off-by: Kees Cook <[email protected]>
> ---
> tools/testing/selftests/seccomp/config | 1 +
> tools/testing/selftests/seccomp/seccomp_bpf.c | 10 ++++++++--
> 2 files changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/tools/testing/selftests/seccomp/config b/tools/testing/selftests/seccomp/config
> index db1e11b08c8a..64c19d8eba79 100644
> --- a/tools/testing/selftests/seccomp/config
> +++ b/tools/testing/selftests/seccomp/config
> @@ -1,2 +1,3 @@
> CONFIG_SECCOMP=y
> CONFIG_SECCOMP_FILTER=y
> +CONFIG_USER_NS=y
> diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c
> index c0aa46ce14f6..14b038361549 100644
> --- a/tools/testing/selftests/seccomp/seccomp_bpf.c
> +++ b/tools/testing/selftests/seccomp/seccomp_bpf.c
> @@ -3439,7 +3439,10 @@ TEST(user_notification_child_pid_ns)
> struct seccomp_notif req = {};
> struct seccomp_notif_resp resp = {};
>
> - ASSERT_EQ(unshare(CLONE_NEWUSER | CLONE_NEWPID), 0);
> + ASSERT_EQ(unshare(CLONE_NEWUSER | CLONE_NEWPID), 0) {
> + if (errno == EINVAL)
> + SKIP(return, "kernel missing CLONE_NEWUSER support");
> + };
>
> listener = user_trap_syscall(__NR_getppid,
> SECCOMP_FILTER_FLAG_NEW_LISTENER);
> @@ -3504,7 +3507,10 @@ TEST(user_notification_sibling_pid_ns)
> }
>
> /* Create the sibling ns, and sibling in it. */
> - ASSERT_EQ(unshare(CLONE_NEWPID), 0);
> + ASSERT_EQ(unshare(CLONE_NEWPID), 0) {
> + if (errno == EPERM)
> + SKIP(return, "CLONE_NEWPID requires CAP_SYS_ADMIN");
> + }
> ASSERT_EQ(errno, 0);

For this one, I think we can just put an unshare(CLONE_NEWUSER) at
the top so the test still runs. This seems works for me unprivileged:

diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c
index 252140a52553..65e3642539f9 100644
--- a/tools/testing/selftests/seccomp/seccomp_bpf.c
+++ b/tools/testing/selftests/seccomp/seccomp_bpf.c
@@ -3482,6 +3482,11 @@ TEST(user_notification_sibling_pid_ns)
TH_LOG("Kernel does not support PR_SET_NO_NEW_PRIVS!");
}

+ ASSERT_EQ(unshare(CLONE_NEWUSER), 0) {
+ if (errno == EINVAL)
+ SKIP(return, "kernel missing CLONE_NEWUSER support");
+ };
+
listener = user_trap_syscall(__NR_getppid,
SECCOMP_FILTER_FLAG_NEW_LISTENER);
ASSERT_GE(listener, 0);