pasta accesses /etc/resolv.conf, which needs search permissions
in openSUSE since the folder structure for the older
sysconfig-netconfig is different than in fedora (which uses
systemd-resolved)

this replaces the manual allow rules with the sysnet_read_config
interface in passt and pasta

Adresses:

----
time->Fri Jul 25 15:57:16 2025
type=AVC msg=audit(1753451836.581:16831): avc:  denied  { search } for  pid=44182 comm="pasta" name="netconfig" dev="tmpfs" ino=2449 scontext=unconfined_u:unconfined_r:pasta_t:s0-s0:c0.c1023 tcontext=system_u:object_r:net_conf_t:s0 tclass=dir permissive=0
----
time->Fri Jul 25 15:58:10 2025
type=AVC msg=audit(1753451890.317:17123): avc:  denied  { search } for  pid=45022 comm="pasta" name="netconfig" dev="tmpfs" ino=2449 scontext=unconfined_u:unconfined_r:pasta_t:s0-s0:c0.c1023 tcontext=system_u:object_r:net_conf_t:s0 tclass=dir permissive=0
----
time->Fri Jul 25 16:01:53 2025
type=AVC msg=audit(1753452113.557:17289): avc:  denied  { search } for  pid=45999 comm="pasta" name="netconfig" dev="tmpfs" ino=2449 scontext=unconfined_u:unconfined_r:pasta_t:s0-s0:c0.c1023 tcontext=system_u:object_r:net_conf_t:s0 tclass=dir permissive=0

Signed-off-by: Cathy Hu <cathy.hu@suse.com>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

Commit 59cc89f ("udp, udp_flow: Track our specific address on socket
interfaces") added a getsockname() call in udp_flow_new(). This requires
getattr. Fixes "Flow 0 (UDP flow): Unable to determine local address:
Permission denied" errors in muvm/passt on Fedora Linux 42 with SELinux.

The SELinux audit message is

| type=AVC msg=audit(1746083799.606:235): avc:  denied  { getattr } for
|   pid=2961 comm="passt" laddr=127.0.0.1 lport=49221
|   faddr=127.0.0.53 fport=53
|   scontext=unconfined_u:unconfined_r:passt_t:s0-s0:c0.c1023
|   tcontext=unconfined_u:unconfined_r:passt_t:s0-s0:c0.c1023
|   tclass=udp_socket permissive=0

Fixes: 59cc89f4cc01 ("udp, udp_flow: Track our specific address on socket interfaces")
Link: https://bugzilla.redhat.com/show_bug.cgi?id=2363238
Signed-off-by: Janne Grunau <janne-psst@jannau.net>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

Here are a bunch of workarounds and a couple of fixes for libvirt
usage which are rather hard to split into single logical patches
as there appear to be some obscure dependencies between some of them:

- passt-repair needs to have an exec_type typeattribute (otherwise
  the policy for lsmd(1) causes a violation on getattr on its
  executable) file, and that typeattribute just happened to be there
  for passt as a result of init_daemon_domain(), but passt-repair
  isn't a daemon, so we need an explicit corecmd_executable_file()

- passt-repair needs a workaround, which I'll revisit once
  https://github.com/fedora-selinux/selinux-policy/issues/2579 is
  solved, for usage with libvirt: allow it to use qemu_var_run_t
  and virt_var_run_t sockets

- add 'bpf' and 'dac_read_search' capabilities for passt-repair:
  they are needed (for whatever reason I didn't investigate) to
  actually receive socket files via SCM_RIGHTS

- passt needs further workarounds in the sense of
  https://github.com/fedora-selinux/selinux-policy/issues/2579:
  allow it to use map and use svirt_tmpfs_t (not just svirt_image_t):
  it depends on where the libvirt guest image is

- ...it also needs to map /dev/null if <access mode='shared'/> is
  enabled in libvirt's XML for the memoryBacking object, for
  vhost-user operation

- and 'ioctl' on the TCP socket appears to be actually needed, on top
  of 'getattr', to dump some socket parameters

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

This implements flow preparation on the source, transfer of data with
a format roughly inspired by struct tcp_tap_conn, plus a specific
structure for parameters that don't fit in the flow table, and flow
insertion on the target, with all the appropriate window options,
window scaling, MSS, etc.

Contents of pending queues are transferred as well.

The target side is rather convoluted because we first need to create
sockets and switch them to repair mode, before we can apply options
that are *not* stored in the flow table. This also means that, if
we're testing this on the same machine, in the same namespace, we need
to close the listening socket on the source before we can start moving
data.

Further, we need to connect() the socket on the target before we can
restore data queues, but we can't do that (again, on the same machine)
as long as the matching source socket is open, which implies an
arbitrary limit on queue sizes we can transfer, because we can only
dump pending queues on the source as long as the socket is open, of
course.

Co-authored-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Tested-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

This doesn't actually belong to passt's own policy: we should export
an interface and libvirt's policy should use it, because passt's
policy shouldn't be aware of svirt_image_t at all.

However, libvirt doesn't maintain its own policy, which makes policy
updates rather involved. Add this workaround to ensure --vhost-user
is working in combination with libvirt, as it might take ages before
we can get the proper rule in libvirt's policy.

Reported-by: Laine Stump <laine@redhat.com>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

...other than being convenient, they might be reasonably
representative of typical stand-alone usage.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

If passt or pasta are started as root, we need to read the passwd file
(be it /etc/passwd or whatever sssd provides) to find out UID and GID
of 'nobody' so that we can switch to it.

Instead of a bunch of allow rules for passwd_file_t and sssd macros,
use the more convenient auth_read_passwd() interface which should
cover our usage of getpwnam().

The existing rules weren't actually enough:

  # strace -e openat passt -f
  [...]
  Started as root, will change to nobody.
  openat(AT_FDCWD, "/etc/nsswitch.conf", O_RDONLY|O_CLOEXEC) = 4
  openat(AT_FDCWD, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 4
  openat(AT_FDCWD, "/lib64/libnss_sss.so.2", O_RDONLY|O_CLOEXEC) = 4
  openat(AT_FDCWD, "/var/lib/sss/mc/passwd", O_RDONLY|O_CLOEXEC) = -1 EACCES (Permission denied)
  openat(AT_FDCWD, "/var/lib/sss/mc/passwd", O_RDONLY|O_CLOEXEC) = -1 EACCES (Permission denied)
  openat(AT_FDCWD, "/etc/passwd", O_RDONLY|O_CLOEXEC) = 4

with corresponding SELinux warnings logged in audit.log.

Reported-by: Minxi Hou <mhou@redhat.com>
Analysed-by: Miloš Malik <mmalik@redhat.com>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

Since commit eedc81b6ef55 ("fwd, conf: Probe host's ephemeral ports"),
we might need to read from /proc/sys/net/ipv4/ip_local_port_range in
both passt and pasta.

While pasta was already allowed to open and write /proc/sys/net
entries, read access was missing in SELinux's type enforcement: add
that.

In passt, instead, this is the first time we need to access an entry
there: add everything we need.

Fixes: eedc81b6ef55 ("fwd, conf: Probe host's ephemeral ports")
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

This reverts commit 3fb3f0f7a59498bdea1d199eecfdbae6c608f78f: it was
meant as a patch for Fedora 37 (and no later versions), not something
I should have merged upstream.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

If passt is started with --fd to talk over a pre-opened UNIX domain
socket, we don't really know what label might be associated to it,
but at least for an unconfined_t socket, this bit of policy wouldn't
belong to anywhere else: enable that here.

This is rather loose, of course, but on the other hand passt will
sandbox itself into an empty filesystem, so we're not really adding
much to the attack surface except for what --fd is supposed to do.

Reported-by: Matej Hrica <mhrica@redhat.com>
Link: https://bugzilla.redhat.com/show_bug.cgi?id=2247221
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>