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Allow kernel_t to manage and relabel all files #1893

Merged
merged 2 commits into from
Oct 6, 2023
Merged

Allow kernel_t to manage and relabel all files #1893

merged 2 commits into from
Oct 6, 2023

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WOnder93
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@WOnder93 WOnder93 commented Oct 6, 2023

Extend the abitlity to manage all files also to character & block device files and also allow relabeling any file.

This is required for early boot overlay mounts to fully work, but may be needed for other legitimate oprations as well.

See also: ostreedev/ostree#3062

@WOnder93
Add missing optional_policy() to files_relabel_all_files()
0366c6e 
The calls to interfaces from other modules must be enclosed in
optional_policy(), otherwise the usage of this interface may lead to
build errors.

Signed-off-by: Ondrej Mosnacek <[email protected]>
@WOnder93
Allow kernel_t to manage and relabel all files
2f17241 
Extend the abitlity to manage all files also to character & block
device files and also allow relabeling any file.

This is required for early boot overlay mounts to fully work, but may be
needed for other legitimate oprations as well.

See also: ostreedev/ostree#3062

Signed-off-by: Ondrej Mosnacek <[email protected]>
@WOnder93 WOnder93 force-pushed the more-early-boot-overlay-fixes branch from aaa4049 to 2f17241 Compare October 6, 2023 12:42
@WOnder93 WOnder93 mentioned this pull request Oct 6, 2023
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@rhatdan
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rhatdan commented Oct 6, 2023

LGTM, but I still believe unconfined_domain(kernel_t) should be the default.

@zpytela
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zpytela commented Oct 6, 2023

Other file classes (lnk, sock, pipe) are not needed to be managed?

@alexlarsson
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Other file classes (lnk, sock, pipe) are not needed to be managed?

These are already allowed via files_manage_all_files(kernel_t) in kernel.te.

@alexlarsson
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lgtm

@rhatdan rhatdan merged commit ce9c09a into fedora-selinux:rawhide Oct 6, 2023
7 checks passed
alexlarsson added a commit to alexlarsson/ostree that referenced this pull request Oct 9, 2023
@alexlarsson
Support transient /etc
bc9d292 
If the `prepare-root.conf` file contains:
```
[etc]
transient=yes
```

Then during prepare-root, an overlayfs is mounted as /etc, with the
upper dir being in /run. If composefs is used, the lower dir is
`usr/etc` from the composefs image , or it is the deployed
`$deploydir/usr/etc`.

Note that for this to work with selinux, the commit must have been
built with OSTREE_REPO_COMMIT_MODIFIER_FLAGS_USRETC_AS_ETC. Otherwise
the lowerdir (/usr/etc) will have the wrong selinux contexts for the
final location of the mount (/etc).

We also set the transient-etc key in the ostree-booted file, pointing it
to the directory that is used for the overlayfs.

There are some additional work happening in ostree-remount, mostly
related to selinux (as this needs to happen post selinux policy
load):

 * Recent versions of selinux-poliy have issues with the overlayfs
   mount being kernel_t, and that is not allowed to manage files as
   needed. This is fixed in
   fedora-selinux/selinux-policy#1893

 * Any /etc files created in the initramfs will not be labeled,
   because the selinux policy has not been loaded. In addition, the
   upper dir is on a tmpfs, and any manually set xattr-based selinux
   labels on those are reset during policy load. To work around this
   ostree-remount will relabel all files on /etc that have
   corresponding files in overlayfs upper dir.

 * During early boot, systemd mounts /run/machine-id on top of
   /etc/machine-id (as /etc is readonly). Later during boot, when etc
   is readwrite, systemd-machine-id-commit.service will remove the
   mount and update the real file under it with the right content. To
   ensure that this keeps working, we need to ensure that when we
   relabel /etc/machine-id we relabel the real (covered) file, not the
   temporary bind-mount.

 * ostree-remount no longer needs to remount /etc read-only in the
   transient-etc case.

Signed-off-by: Alexander Larsson <[email protected]>
alexlarsson added a commit to alexlarsson/ostree that referenced this pull request Oct 9, 2023
@alexlarsson
Support transient /etc
50de0ff 
If the `prepare-root.conf` file contains:
```
[etc]
transient=yes
```

Then during prepare-root, an overlayfs is mounted as /etc, with the
upper dir being in /run. If composefs is used, the lower dir is
`usr/etc` from the composefs image , or it is the deployed
`$deploydir/usr/etc`.

Note that for this to work with selinux, the commit must have been
built with OSTREE_REPO_COMMIT_MODIFIER_FLAGS_USRETC_AS_ETC. Otherwise
the lowerdir (/usr/etc) will have the wrong selinux contexts for the
final location of the mount (/etc).

We also set the transient-etc key in the ostree-booted file, pointing it
to the directory that is used for the overlayfs.

There are some additional work happening in ostree-remount, mostly
related to selinux (as this needs to happen post selinux policy
load):

 * Recent versions of selinux-poliy have issues with the overlayfs
   mount being kernel_t, and that is not allowed to manage files as
   needed. This is fixed in
   fedora-selinux/selinux-policy#1893

 * Any /etc files created in the initramfs will not be labeled,
   because the selinux policy has not been loaded. In addition, the
   upper dir is on a tmpfs, and any manually set xattr-based selinux
   labels on those are reset during policy load. To work around this
   ostree-remount will relabel all files on /etc that have
   corresponding files in overlayfs upper dir.

 * During early boot, systemd mounts /run/machine-id on top of
   /etc/machine-id (as /etc is readonly). Later during boot, when etc
   is readwrite, systemd-machine-id-commit.service will remove the
   mount and update the real file under it with the right content. To
   ensure that this keeps working, we need to ensure that when we
   relabel /etc/machine-id we relabel the real (covered) file, not the
   temporary bind-mount.

 * ostree-remount no longer needs to remount /etc read-only in the
   transient-etc case.

Signed-off-by: Alexander Larsson <[email protected]>
alexlarsson added a commit to alexlarsson/ostree that referenced this pull request Oct 12, 2023
@alexlarsson
Support transient /etc
186f210 
If the `prepare-root.conf` file contains:
```
[etc]
transient=yes
```

Then during prepare-root, an overlayfs is mounted as /etc, with the
upper dir being in /run. If composefs is used, the lower dir is
`usr/etc` from the composefs image , or it is the deployed
`$deploydir/usr/etc`.

Note that for this to work with selinux, the commit must have been
built with OSTREE_REPO_COMMIT_MODIFIER_FLAGS_USRETC_AS_ETC. Otherwise
the lowerdir (/usr/etc) will have the wrong selinux contexts for the
final location of the mount (/etc).

We also set the transient-etc key in the ostree-booted file, pointing it
to the directory that is used for the overlayfs.

There are some additional work happening in ostree-remount, mostly
related to selinux (as this needs to happen post selinux policy
load):

 * Recent versions of selinux-poliy have issues with the overlayfs
   mount being kernel_t, and that is not allowed to manage files as
   needed. This is fixed in
   fedora-selinux/selinux-policy#1893

 * Any /etc files created in the initramfs will not be labeled,
   because the selinux policy has not been loaded. In addition, the
   upper dir is on a tmpfs, and any manually set xattr-based selinux
   labels on those are reset during policy load. To work around this
   ostree-remount will relabel all files on /etc that have
   corresponding files in overlayfs upper dir.

 * During early boot, systemd mounts /run/machine-id on top of
   /etc/machine-id (as /etc is readonly). Later during boot, when etc
   is readwrite, systemd-machine-id-commit.service will remove the
   mount and update the real file under it with the right content. To
   ensure that this keeps working, we need to ensure that when we
   relabel /etc/machine-id we relabel the real (covered) file, not the
   temporary bind-mount.

 * ostree-remount no longer needs to remount /etc read-only in the
   transient-etc case.

Signed-off-by: Alexander Larsson <[email protected]>
alexlarsson added a commit to alexlarsson/ostree that referenced this pull request Oct 12, 2023
@alexlarsson
Support transient /etc
f617a34 
If the `prepare-root.conf` file contains:
```
[etc]
transient=yes
```

Then during prepare-root, an overlayfs is mounted as /etc, with the
upper dir being in /run. If composefs is used, the lower dir is
`usr/etc` from the composefs image , or it is the deployed
`$deploydir/usr/etc`.

Note that for this to work with selinux, the commit must have been
built with OSTREE_REPO_COMMIT_MODIFIER_FLAGS_USRETC_AS_ETC. Otherwise
the lowerdir (/usr/etc) will have the wrong selinux contexts for the
final location of the mount (/etc).

We also set the transient-etc key in the ostree-booted file, pointing it
to the directory that is used for the overlayfs.

There are some additional work happening in ostree-remount, mostly
related to selinux (as this needs to happen post selinux policy
load):

 * Recent versions of selinux-poliy have issues with the overlayfs
   mount being kernel_t, and that is not allowed to manage files as
   needed. This is fixed in
   fedora-selinux/selinux-policy#1893

 * Any /etc files created in the initramfs will not be labeled,
   because the selinux policy has not been loaded. In addition, the
   upper dir is on a tmpfs, and any manually set xattr-based selinux
   labels on those are reset during policy load. To work around this
   ostree-remount will relabel all files on /etc that have
   corresponding files in overlayfs upper dir.

 * During early boot, systemd mounts /run/machine-id on top of
   /etc/machine-id (as /etc is readonly). Later during boot, when etc
   is readwrite, systemd-machine-id-commit.service will remove the
   mount and update the real file under it with the right content. To
   ensure that this keeps working, we need to ensure that when we
   relabel /etc/machine-id we relabel the real (covered) file, not the
   temporary bind-mount.

 * ostree-remount no longer needs to remount /etc read-only in the
   transient-etc case.

Signed-off-by: Alexander Larsson <[email protected]>
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@WOnder93 @rhatdan @zpytela @alexlarsson @cgwalters