8/17/2023 6:08 PM, Mickaël Salaün пишет:

On Sat, Aug 12, 2023 at 05:37:00PM +0300, Konstantin Meskhidze (A) wrote:

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7/12/2023 10:02 AM, Mickaël Salaün пишет:

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On 06/07/2023 16:55, Mickaël Salaün wrote:

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From: Konstantin Meskhidze <redacted>

This patch is a revamp of the v11 tests [1] with new tests (see the
"Changes since v11" description).  I (Mickaël) only added the following
todo list and the "Changes since v11" sections in this commit message.
I think this patch is good but it would appreciate reviews.
You can find the diff of my changes here but it is not really readable:
https://git.kernel.org/mic/c/78edf722fba5 (landlock-net-v11 branch)
[1] https://lore.kernel.org/all/20230515161339.631577-11-konstantin.meskhidze@huawei.com/ (local)
TODO:
- Rename all "net_service" to "net_port".
- Fix the two kernel bugs found with the new tests.
- Update this commit message with a small description of all tests.

[...]

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We should also add a test to make sure errno is the same with and
without sandboxing when using port 0 for connect and consistent with
bind (using an available port). The test fixture and variants should be
quite similar to the "ipv4" ones, but we can also add AF_INET6 variants,
which will result in 8 "ip" variants:

TEST_F(ip, port_zero)
{
	if (variant->sandbox == TCP_SANDBOX) {
		/* Denies any connect and bind. */
	}
	/* Checks errno for port 0. */
}

As I understand the would be the next test cases:

	1. ip4, sandboxed, bind port 0 -> should return EACCES (denied by
landlock).

Without any allowed port, yes. This test case is useful.

By tuning /proc/sys/net/ipv4/ip_local_port_range (see
inet_csk_find_open_port call) we should be able to pick a specific
allowed port and test it.  We can also test for the EADDRINUSE error to
make sure error ordering is correct (compared with -EACCES).

   Sorry, did not get this case. Could please explain it with more details?

However, I think the current LSM API don't enable to infer this random
port because the LSM hook is called before a port is picked.  If this is
correct, the best way to control port binding would be to always deny
binding on port zero/random (when restricting port binding, whatever
exception rules are in place). This explanation should be part of a
comment for this specific exception.

   Yep, if some LSM rule (for bind) has been applied a with specific 
port, other attemps to bind with zero/random ports would be refused by 
LSM security checks.

Cc Paul

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	2. ip4, non-sandboxed, bind port 0 -> should return 0 (should be bounded to
random port).

I think so but we need to make sure the random port cannot be < 1024, I
guess with /proc/sys/net/ipv4/ip_local_port_range but I don't know for
IPv6.

   For ipv4 when connecting to a server a client binds to a random port 
within /proc/sys/net/ipv4/ip_local_port_range, by default one my machine
this range is: cat /proc/sys/net/ipv4/ip_local_port_range
32768   60999.
But for ipv6 there is no such tuning range.

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	3. ip6, sandboxed, bind port 0 -> should return EACCES (denied by
landlock).
	4. ip6, non-sandboxed, bind port 0 -> should return 0 (should be bounded to
random port).
	5. ip4, sandboxed, bind some available port, connect port 0 -> should
return -EACCES (denied by landlock).

Yes, but don't need to bind to anything (same for the next ones).

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	6. ip4, non-sandboxed, bind some available port, connect port 0 -> should
return ECONNREFUSED.

Yes, but without any binding.

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	7. ip6, sandboxed, bind some available port, connect port 0 -> should
return -EACCES (denied by landlock)
	8. ip6, non-sandboxed, some bind available port, connect port 0 -> should
return ECONNREFUSED.

Correct?

Thinking more about this case, being able to add a rule with port zero
*for a connect action* looks legitimate.  A rule with both connect and
bind actions on port zero should then be denied.  We should fix
add_rule_net_service() and test that (with a first layer allowing port
zero, and a second without rule, for connect).

  So with first rule allowing port 0 connect action, the second rule 
with some another port and connect action, as a result test should allow 
that. Correct?

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+FIXTURE(inet)
+{
+	struct service_fixture srv0, srv1;
+};

The "inet" variants are useless and should be removed. The "inet"
fixture can then be renamed to "ipv4_tcp".

  So inet should be changed to ipv4_tcp and ipv6_tcp with next variants:

  - ipv4_tcp.no_sandbox_with_ipv4.port_endianness
  - ipv4_tcp.sandbox_with_ipv4.port_endianness
  - ipv6_tcp.no_sandbox_with_ipv6.port_endianness
  - ipv6_tcp.sandbox_with_ipv6.port_endianness
????

   in this case we need double copy of TEST_F(inet, port_endianness) :
	TEST_F(ipv4_tcp, port_endianness)
	TEST_F(ipv6_tcp, port_endianness)

There is no need for any variant for the port_endianness test. You can
rename "inet" to "ipv4_tcp" (and not "inet_tcp" like I said before).
.