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fuse: Add posix ACL support Add a new INIT flag, FUSE_POSIX_ACL, for negotiating ACL support with userspace. When it is set in the INIT response, ACL support will be enabled. ACL support also implies "default_permissions". When ACL support is enabled, the kernel will cache and have responsibility for enforcing ACLs. ACL xattrs will be passed to userspace, which is responsible for updating the ACLs in the filesystem, keeping the file mode in sync, and inheritance of default ACLs when new filesystem nodes are created. Signed-off-by: Seth Forshee <seth.forshee@canonical.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-08-29 08:46:37 -05:00
fuse: fixes after adapting to new posix acl api This cycle we ported all filesystems to the new posix acl api. While looking at further simplifications in this area to remove the last remnants of the generic dummy posix acl handlers we realized that we regressed fuse daemons that don't set FUSE_POSIX_ACL but still make use of posix acls. With the change to a dedicated posix acl api interacting with posix acls doesn't go through the old xattr codepaths anymore and instead only relies the get acl and set acl inode operations. Before this change fuse daemons that don't set FUSE_POSIX_ACL were able to get and set posix acl albeit with two caveats. First, that posix acls aren't cached. And second, that they aren't used for permission checking in the vfs. We regressed that use-case as we currently refuse to retrieve any posix acls if they aren't enabled via FUSE_POSIX_ACL. So older fuse daemons would see a change in behavior. We can restore the old behavior in multiple ways. We could change the new posix acl api and look for a dedicated xattr handler and if we find one prefer that over the dedicated posix acl api. That would break the consistency of the new posix acl api so we would very much prefer not to do that. We could introduce a new ACL_*_CACHE sentinel that would instruct the vfs permission checking codepath to not call into the filesystem and ignore acls. But a more straightforward fix for v6.2 is to do the same thing that Overlayfs does and give fuse a separate get acl method for permission checking. Overlayfs uses this to express different needs for vfs permission lookup and acl based retrieval via the regular system call path as well. Let fuse do the same for now. This way fuse can continue to refuse to retrieve posix acls for daemons that don't set FUSE_POSXI_ACL for permission checking while allowing a fuse server to retrieve it via the usual system calls. In the future, we could extend the get acl inode operation to not just pass a simple boolean to indicate rcu lookup but instead make it a flag argument. Then in addition to passing the information that this is an rcu lookup to the filesystem we could also introduce a flag that tells the filesystem that this is a request from the vfs to use these acls for permission checking. Then fuse could refuse the get acl request for permission checking when the daemon doesn't have FUSE_POSIX_ACL set in the same get acl method. This would also help Overlayfs and allow us to remove the second method for it as well. But since that change is more invasive as we need to update the get acl inode operation for multiple filesystems we should not do this as a fix for v6.2. Instead we will do this for the v6.3 merge window. Fwiw, since posix acls are now always correctly translated in the new posix acl api we could also allow them to be used for daemons without FUSE_POSIX_ACL that are not mounted on the host. But this is behavioral change and again if dones should be done for v6.3. For now, let's just restore the original behavior. A nice side-effect of this change is that for fuse daemons with and without FUSE_POSIX_ACL the same code is used for posix acls in a backwards compatible way. This also means we can remove the legacy xattr handlers completely. We've also added comments to explain the expected behavior for daemons without FUSE_POSIX_ACL into the code. Fixes: 318e66856dde ("xattr: use posix acl api") Signed-off-by: Seth Forshee (Digital Ocean) <sforshee@kernel.org> Reviewed-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-01-20 12:55:04 +01:00
fuse: Add posix ACL support Add a new INIT flag, FUSE_POSIX_ACL, for negotiating ACL support with userspace. When it is set in the INIT response, ACL support will be enabled. ACL support also implies "default_permissions". When ACL support is enabled, the kernel will cache and have responsibility for enforcing ACLs. ACL xattrs will be passed to userspace, which is responsible for updating the ACLs in the filesystem, keeping the file mode in sync, and inheritance of default ACLs when new filesystem nodes are created. Signed-off-by: Seth Forshee <seth.forshee@canonical.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-08-29 08:46:37 -05:00
vfs: add rcu argument to ->get_acl() callback Add a rcu argument to the ->get_acl() callback to allow get_cached_acl_rcu() to call the ->get_acl() method in the next patch. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2021-08-18 22:08:24 +02:00
fuse: fix bad inode Jan Kara's analysis of the syzbot report (edited): The reproducer opens a directory on FUSE filesystem, it then attaches dnotify mark to the open directory. After that a fuse_do_getattr() call finds that attributes returned by the server are inconsistent, and calls make_bad_inode() which, among other things does: inode->i_mode = S_IFREG; This then confuses dnotify which doesn't tear down its structures properly and eventually crashes. Avoid calling make_bad_inode() on a live inode: switch to a private flag on the fuse inode. Also add the test to ops which the bad_inode_ops would have caught. This bug goes back to the initial merge of fuse in 2.6.14... Reported-by: syzbot+f427adf9324b92652ccc@syzkaller.appspotmail.com Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Tested-by: Jan Kara <jack@suse.cz> Cc: <stable@vger.kernel.org>
2020-12-10 15:33:14 +01:00
fuse: fixes after adapting to new posix acl api This cycle we ported all filesystems to the new posix acl api. While looking at further simplifications in this area to remove the last remnants of the generic dummy posix acl handlers we realized that we regressed fuse daemons that don't set FUSE_POSIX_ACL but still make use of posix acls. With the change to a dedicated posix acl api interacting with posix acls doesn't go through the old xattr codepaths anymore and instead only relies the get acl and set acl inode operations. Before this change fuse daemons that don't set FUSE_POSIX_ACL were able to get and set posix acl albeit with two caveats. First, that posix acls aren't cached. And second, that they aren't used for permission checking in the vfs. We regressed that use-case as we currently refuse to retrieve any posix acls if they aren't enabled via FUSE_POSIX_ACL. So older fuse daemons would see a change in behavior. We can restore the old behavior in multiple ways. We could change the new posix acl api and look for a dedicated xattr handler and if we find one prefer that over the dedicated posix acl api. That would break the consistency of the new posix acl api so we would very much prefer not to do that. We could introduce a new ACL_*_CACHE sentinel that would instruct the vfs permission checking codepath to not call into the filesystem and ignore acls. But a more straightforward fix for v6.2 is to do the same thing that Overlayfs does and give fuse a separate get acl method for permission checking. Overlayfs uses this to express different needs for vfs permission lookup and acl based retrieval via the regular system call path as well. Let fuse do the same for now. This way fuse can continue to refuse to retrieve posix acls for daemons that don't set FUSE_POSXI_ACL for permission checking while allowing a fuse server to retrieve it via the usual system calls. In the future, we could extend the get acl inode operation to not just pass a simple boolean to indicate rcu lookup but instead make it a flag argument. Then in addition to passing the information that this is an rcu lookup to the filesystem we could also introduce a flag that tells the filesystem that this is a request from the vfs to use these acls for permission checking. Then fuse could refuse the get acl request for permission checking when the daemon doesn't have FUSE_POSIX_ACL set in the same get acl method. This would also help Overlayfs and allow us to remove the second method for it as well. But since that change is more invasive as we need to update the get acl inode operation for multiple filesystems we should not do this as a fix for v6.2. Instead we will do this for the v6.3 merge window. Fwiw, since posix acls are now always correctly translated in the new posix acl api we could also allow them to be used for daemons without FUSE_POSIX_ACL that are not mounted on the host. But this is behavioral change and again if dones should be done for v6.3. For now, let's just restore the original behavior. A nice side-effect of this change is that for fuse daemons with and without FUSE_POSIX_ACL the same code is used for posix acls in a backwards compatible way. This also means we can remove the legacy xattr handlers completely. We've also added comments to explain the expected behavior for daemons without FUSE_POSIX_ACL into the code. Fixes: 318e66856dde ("xattr: use posix acl api") Signed-off-by: Seth Forshee (Digital Ocean) <sforshee@kernel.org> Reviewed-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-01-20 12:55:04 +01:00
fuse: Add posix ACL support Add a new INIT flag, FUSE_POSIX_ACL, for negotiating ACL support with userspace. When it is set in the INIT response, ACL support will be enabled. ACL support also implies "default_permissions". When ACL support is enabled, the kernel will cache and have responsibility for enforcing ACLs. ACL xattrs will be passed to userspace, which is responsible for updating the ACLs in the filesystem, keeping the file mode in sync, and inheritance of default ACLs when new filesystem nodes are created. Signed-off-by: Seth Forshee <seth.forshee@canonical.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-08-29 08:46:37 -05:00
fuse: Support fuse filesystems outside of init_user_ns In order to support mounts from namespaces other than init_user_ns, fuse must translate uids and gids to/from the userns of the process servicing requests on /dev/fuse. This patch does that, with a couple of restrictions on the namespace: - The userns for the fuse connection is fixed to the namespace from which /dev/fuse is opened. - The namespace must be the same as s_user_ns. These restrictions simplify the implementation by avoiding the need to pass around userns references and by allowing fuse to rely on the checks in setattr_prepare for ownership changes. Either restriction could be relaxed in the future if needed. For cuse the userns used is the opener of /dev/cuse. Semantically the cuse support does not appear safe for unprivileged users. Practically the permissions on /dev/cuse only make it accessible to the global root user. If something slips through the cracks in a user namespace the only users who will be able to use the cuse device are those users mapped into the user namespace. Translation in the posix acl is updated to use the uuser namespace of the filesystem. Avoiding cases which might bypass this translation is handled in a following change. This change is stronlgy based on a similar change from Seth Forshee and Dongsu Park. Cc: Seth Forshee <seth.forshee@canonical.com> Cc: Dongsu Park <dongsu@kinvolk.io> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-02-21 11:18:07 -06:00
fuse: Add posix ACL support Add a new INIT flag, FUSE_POSIX_ACL, for negotiating ACL support with userspace. When it is set in the INIT response, ACL support will be enabled. ACL support also implies "default_permissions". When ACL support is enabled, the kernel will cache and have responsibility for enforcing ACLs. ACL xattrs will be passed to userspace, which is responsible for updating the ACLs in the filesystem, keeping the file mode in sync, and inheritance of default ACLs when new filesystem nodes are created. Signed-off-by: Seth Forshee <seth.forshee@canonical.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-08-29 08:46:37 -05:00
fuse: fixes after adapting to new posix acl api This cycle we ported all filesystems to the new posix acl api. While looking at further simplifications in this area to remove the last remnants of the generic dummy posix acl handlers we realized that we regressed fuse daemons that don't set FUSE_POSIX_ACL but still make use of posix acls. With the change to a dedicated posix acl api interacting with posix acls doesn't go through the old xattr codepaths anymore and instead only relies the get acl and set acl inode operations. Before this change fuse daemons that don't set FUSE_POSIX_ACL were able to get and set posix acl albeit with two caveats. First, that posix acls aren't cached. And second, that they aren't used for permission checking in the vfs. We regressed that use-case as we currently refuse to retrieve any posix acls if they aren't enabled via FUSE_POSIX_ACL. So older fuse daemons would see a change in behavior. We can restore the old behavior in multiple ways. We could change the new posix acl api and look for a dedicated xattr handler and if we find one prefer that over the dedicated posix acl api. That would break the consistency of the new posix acl api so we would very much prefer not to do that. We could introduce a new ACL_*_CACHE sentinel that would instruct the vfs permission checking codepath to not call into the filesystem and ignore acls. But a more straightforward fix for v6.2 is to do the same thing that Overlayfs does and give fuse a separate get acl method for permission checking. Overlayfs uses this to express different needs for vfs permission lookup and acl based retrieval via the regular system call path as well. Let fuse do the same for now. This way fuse can continue to refuse to retrieve posix acls for daemons that don't set FUSE_POSXI_ACL for permission checking while allowing a fuse server to retrieve it via the usual system calls. In the future, we could extend the get acl inode operation to not just pass a simple boolean to indicate rcu lookup but instead make it a flag argument. Then in addition to passing the information that this is an rcu lookup to the filesystem we could also introduce a flag that tells the filesystem that this is a request from the vfs to use these acls for permission checking. Then fuse could refuse the get acl request for permission checking when the daemon doesn't have FUSE_POSIX_ACL set in the same get acl method. This would also help Overlayfs and allow us to remove the second method for it as well. But since that change is more invasive as we need to update the get acl inode operation for multiple filesystems we should not do this as a fix for v6.2. Instead we will do this for the v6.3 merge window. Fwiw, since posix acls are now always correctly translated in the new posix acl api we could also allow them to be used for daemons without FUSE_POSIX_ACL that are not mounted on the host. But this is behavioral change and again if dones should be done for v6.3. For now, let's just restore the original behavior. A nice side-effect of this change is that for fuse daemons with and without FUSE_POSIX_ACL the same code is used for posix acls in a backwards compatible way. This also means we can remove the legacy xattr handlers completely. We've also added comments to explain the expected behavior for daemons without FUSE_POSIX_ACL into the code. Fixes: 318e66856dde ("xattr: use posix acl api") Signed-off-by: Seth Forshee (Digital Ocean) <sforshee@kernel.org> Reviewed-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-01-20 12:55:04 +01:00
fs.idmapped.v6.3 -----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQRAhzRXHqcMeLMyaSiRxhvAZXjcogUCY+5NlQAKCRCRxhvAZXjc orOaAP9i2h3OJy95nO2Fpde0Bt2UT+oulKCCcGlvXJ8/+TQpyQD/ZQq47gFQ0EAz Br5NxeyGeecAb0lHpFz+CpLGsxMrMwQ= =+BG5 -----END PGP SIGNATURE----- Merge tag 'fs.idmapped.v6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/idmapping Pull vfs idmapping updates from Christian Brauner: - Last cycle we introduced the dedicated struct mnt_idmap type for mount idmapping and the required infrastucture in 256c8aed2b42 ("fs: introduce dedicated idmap type for mounts"). As promised in last cycle's pull request message this converts everything to rely on struct mnt_idmap. Currently we still pass around the plain namespace that was attached to a mount. This is in general pretty convenient but it makes it easy to conflate namespaces that are relevant on the filesystem with namespaces that are relevant on the mount level. Especially for non-vfs developers without detailed knowledge in this area this was a potential source for bugs. This finishes the conversion. Instead of passing the plain namespace around this updates all places that currently take a pointer to a mnt_userns with a pointer to struct mnt_idmap. Now that the conversion is done all helpers down to the really low-level helpers only accept a struct mnt_idmap argument instead of two namespace arguments. Conflating mount and other idmappings will now cause the compiler to complain loudly thus eliminating the possibility of any bugs. This makes it impossible for filesystem developers to mix up mount and filesystem idmappings as they are two distinct types and require distinct helpers that cannot be used interchangeably. Everything associated with struct mnt_idmap is moved into a single separate file. With that change no code can poke around in struct mnt_idmap. It can only be interacted with through dedicated helpers. That means all filesystems are and all of the vfs is completely oblivious to the actual implementation of idmappings. We are now also able to extend struct mnt_idmap as we see fit. For example, we can decouple it completely from namespaces for users that don't require or don't want to use them at all. We can also extend the concept of idmappings so we can cover filesystem specific requirements. In combination with the vfs{g,u}id_t work we finished in v6.2 this makes this feature substantially more robust and thus difficult to implement wrong by a given filesystem and also protects the vfs. - Enable idmapped mounts for tmpfs and fulfill a longstanding request. A long-standing request from users had been to make it possible to create idmapped mounts for tmpfs. For example, to share the host's tmpfs mount between multiple sandboxes. This is a prerequisite for some advanced Kubernetes cases. Systemd also has a range of use-cases to increase service isolation. And there are more users of this. However, with all of the other work going on this was way down on the priority list but luckily someone other than ourselves picked this up. As usual the patch is tiny as all the infrastructure work had been done multiple kernel releases ago. In addition to all the tests that we already have I requested that Rodrigo add a dedicated tmpfs testsuite for idmapped mounts to xfstests. It is to be included into xfstests during the v6.3 development cycle. This should add a slew of additional tests. * tag 'fs.idmapped.v6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/idmapping: (26 commits) shmem: support idmapped mounts for tmpfs fs: move mnt_idmap fs: port vfs{g,u}id helpers to mnt_idmap fs: port fs{g,u}id helpers to mnt_idmap fs: port i_{g,u}id_into_vfs{g,u}id() to mnt_idmap fs: port i_{g,u}id_{needs_}update() to mnt_idmap quota: port to mnt_idmap fs: port privilege checking helpers to mnt_idmap fs: port inode_owner_or_capable() to mnt_idmap fs: port inode_init_owner() to mnt_idmap fs: port acl to mnt_idmap fs: port xattr to mnt_idmap fs: port ->permission() to pass mnt_idmap fs: port ->fileattr_set() to pass mnt_idmap fs: port ->set_acl() to pass mnt_idmap fs: port ->get_acl() to pass mnt_idmap fs: port ->tmpfile() to pass mnt_idmap fs: port ->rename() to pass mnt_idmap fs: port ->mknod() to pass mnt_idmap fs: port ->mkdir() to pass mnt_idmap ...
2023-02-20 11:53:11 -08:00
fuse: fixes after adapting to new posix acl api This cycle we ported all filesystems to the new posix acl api. While looking at further simplifications in this area to remove the last remnants of the generic dummy posix acl handlers we realized that we regressed fuse daemons that don't set FUSE_POSIX_ACL but still make use of posix acls. With the change to a dedicated posix acl api interacting with posix acls doesn't go through the old xattr codepaths anymore and instead only relies the get acl and set acl inode operations. Before this change fuse daemons that don't set FUSE_POSIX_ACL were able to get and set posix acl albeit with two caveats. First, that posix acls aren't cached. And second, that they aren't used for permission checking in the vfs. We regressed that use-case as we currently refuse to retrieve any posix acls if they aren't enabled via FUSE_POSIX_ACL. So older fuse daemons would see a change in behavior. We can restore the old behavior in multiple ways. We could change the new posix acl api and look for a dedicated xattr handler and if we find one prefer that over the dedicated posix acl api. That would break the consistency of the new posix acl api so we would very much prefer not to do that. We could introduce a new ACL_*_CACHE sentinel that would instruct the vfs permission checking codepath to not call into the filesystem and ignore acls. But a more straightforward fix for v6.2 is to do the same thing that Overlayfs does and give fuse a separate get acl method for permission checking. Overlayfs uses this to express different needs for vfs permission lookup and acl based retrieval via the regular system call path as well. Let fuse do the same for now. This way fuse can continue to refuse to retrieve posix acls for daemons that don't set FUSE_POSXI_ACL for permission checking while allowing a fuse server to retrieve it via the usual system calls. In the future, we could extend the get acl inode operation to not just pass a simple boolean to indicate rcu lookup but instead make it a flag argument. Then in addition to passing the information that this is an rcu lookup to the filesystem we could also introduce a flag that tells the filesystem that this is a request from the vfs to use these acls for permission checking. Then fuse could refuse the get acl request for permission checking when the daemon doesn't have FUSE_POSIX_ACL set in the same get acl method. This would also help Overlayfs and allow us to remove the second method for it as well. But since that change is more invasive as we need to update the get acl inode operation for multiple filesystems we should not do this as a fix for v6.2. Instead we will do this for the v6.3 merge window. Fwiw, since posix acls are now always correctly translated in the new posix acl api we could also allow them to be used for daemons without FUSE_POSIX_ACL that are not mounted on the host. But this is behavioral change and again if dones should be done for v6.3. For now, let's just restore the original behavior. A nice side-effect of this change is that for fuse daemons with and without FUSE_POSIX_ACL the same code is used for posix acls in a backwards compatible way. This also means we can remove the legacy xattr handlers completely. We've also added comments to explain the expected behavior for daemons without FUSE_POSIX_ACL into the code. Fixes: 318e66856dde ("xattr: use posix acl api") Signed-off-by: Seth Forshee (Digital Ocean) <sforshee@kernel.org> Reviewed-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-01-20 12:55:04 +01:00
fuse: drop idmap argument from __fuse_get_acl We don't need to have idmap in the __fuse_get_acl as we don't have any use for it. In the current POSIX ACL implementation, idmapped mounts are taken into account on the userspace/kernel border (see vfs_set_acl_idmapped_mnt() and vfs_posix_acl_to_xattr()). Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com> Reviewed-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2024-09-03 17:16:20 +02:00
fuse: fixes after adapting to new posix acl api This cycle we ported all filesystems to the new posix acl api. While looking at further simplifications in this area to remove the last remnants of the generic dummy posix acl handlers we realized that we regressed fuse daemons that don't set FUSE_POSIX_ACL but still make use of posix acls. With the change to a dedicated posix acl api interacting with posix acls doesn't go through the old xattr codepaths anymore and instead only relies the get acl and set acl inode operations. Before this change fuse daemons that don't set FUSE_POSIX_ACL were able to get and set posix acl albeit with two caveats. First, that posix acls aren't cached. And second, that they aren't used for permission checking in the vfs. We regressed that use-case as we currently refuse to retrieve any posix acls if they aren't enabled via FUSE_POSIX_ACL. So older fuse daemons would see a change in behavior. We can restore the old behavior in multiple ways. We could change the new posix acl api and look for a dedicated xattr handler and if we find one prefer that over the dedicated posix acl api. That would break the consistency of the new posix acl api so we would very much prefer not to do that. We could introduce a new ACL_*_CACHE sentinel that would instruct the vfs permission checking codepath to not call into the filesystem and ignore acls. But a more straightforward fix for v6.2 is to do the same thing that Overlayfs does and give fuse a separate get acl method for permission checking. Overlayfs uses this to express different needs for vfs permission lookup and acl based retrieval via the regular system call path as well. Let fuse do the same for now. This way fuse can continue to refuse to retrieve posix acls for daemons that don't set FUSE_POSXI_ACL for permission checking while allowing a fuse server to retrieve it via the usual system calls. In the future, we could extend the get acl inode operation to not just pass a simple boolean to indicate rcu lookup but instead make it a flag argument. Then in addition to passing the information that this is an rcu lookup to the filesystem we could also introduce a flag that tells the filesystem that this is a request from the vfs to use these acls for permission checking. Then fuse could refuse the get acl request for permission checking when the daemon doesn't have FUSE_POSIX_ACL set in the same get acl method. This would also help Overlayfs and allow us to remove the second method for it as well. But since that change is more invasive as we need to update the get acl inode operation for multiple filesystems we should not do this as a fix for v6.2. Instead we will do this for the v6.3 merge window. Fwiw, since posix acls are now always correctly translated in the new posix acl api we could also allow them to be used for daemons without FUSE_POSIX_ACL that are not mounted on the host. But this is behavioral change and again if dones should be done for v6.3. For now, let's just restore the original behavior. A nice side-effect of this change is that for fuse daemons with and without FUSE_POSIX_ACL the same code is used for posix acls in a backwards compatible way. This also means we can remove the legacy xattr handlers completely. We've also added comments to explain the expected behavior for daemons without FUSE_POSIX_ACL into the code. Fixes: 318e66856dde ("xattr: use posix acl api") Signed-off-by: Seth Forshee (Digital Ocean) <sforshee@kernel.org> Reviewed-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-01-20 12:55:04 +01:00
fuse: drop idmap argument from __fuse_get_acl We don't need to have idmap in the __fuse_get_acl as we don't have any use for it. In the current POSIX ACL implementation, idmapped mounts are taken into account on the userspace/kernel border (see vfs_set_acl_idmapped_mnt() and vfs_posix_acl_to_xattr()). Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com> Reviewed-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2024-09-03 17:16:20 +02:00
fuse: fixes after adapting to new posix acl api This cycle we ported all filesystems to the new posix acl api. While looking at further simplifications in this area to remove the last remnants of the generic dummy posix acl handlers we realized that we regressed fuse daemons that don't set FUSE_POSIX_ACL but still make use of posix acls. With the change to a dedicated posix acl api interacting with posix acls doesn't go through the old xattr codepaths anymore and instead only relies the get acl and set acl inode operations. Before this change fuse daemons that don't set FUSE_POSIX_ACL were able to get and set posix acl albeit with two caveats. First, that posix acls aren't cached. And second, that they aren't used for permission checking in the vfs. We regressed that use-case as we currently refuse to retrieve any posix acls if they aren't enabled via FUSE_POSIX_ACL. So older fuse daemons would see a change in behavior. We can restore the old behavior in multiple ways. We could change the new posix acl api and look for a dedicated xattr handler and if we find one prefer that over the dedicated posix acl api. That would break the consistency of the new posix acl api so we would very much prefer not to do that. We could introduce a new ACL_*_CACHE sentinel that would instruct the vfs permission checking codepath to not call into the filesystem and ignore acls. But a more straightforward fix for v6.2 is to do the same thing that Overlayfs does and give fuse a separate get acl method for permission checking. Overlayfs uses this to express different needs for vfs permission lookup and acl based retrieval via the regular system call path as well. Let fuse do the same for now. This way fuse can continue to refuse to retrieve posix acls for daemons that don't set FUSE_POSXI_ACL for permission checking while allowing a fuse server to retrieve it via the usual system calls. In the future, we could extend the get acl inode operation to not just pass a simple boolean to indicate rcu lookup but instead make it a flag argument. Then in addition to passing the information that this is an rcu lookup to the filesystem we could also introduce a flag that tells the filesystem that this is a request from the vfs to use these acls for permission checking. Then fuse could refuse the get acl request for permission checking when the daemon doesn't have FUSE_POSIX_ACL set in the same get acl method. This would also help Overlayfs and allow us to remove the second method for it as well. But since that change is more invasive as we need to update the get acl inode operation for multiple filesystems we should not do this as a fix for v6.2. Instead we will do this for the v6.3 merge window. Fwiw, since posix acls are now always correctly translated in the new posix acl api we could also allow them to be used for daemons without FUSE_POSIX_ACL that are not mounted on the host. But this is behavioral change and again if dones should be done for v6.3. For now, let's just restore the original behavior. A nice side-effect of this change is that for fuse daemons with and without FUSE_POSIX_ACL the same code is used for posix acls in a backwards compatible way. This also means we can remove the legacy xattr handlers completely. We've also added comments to explain the expected behavior for daemons without FUSE_POSIX_ACL into the code. Fixes: 318e66856dde ("xattr: use posix acl api") Signed-off-by: Seth Forshee (Digital Ocean) <sforshee@kernel.org> Reviewed-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-01-20 12:55:04 +01:00
fs: port ->set_acl() to pass mnt_idmap Convert to struct mnt_idmap. Last cycle we merged the necessary infrastructure in 256c8aed2b42 ("fs: introduce dedicated idmap type for mounts"). This is just the conversion to struct mnt_idmap. Currently we still pass around the plain namespace that was attached to a mount. This is in general pretty convenient but it makes it easy to conflate namespaces that are relevant on the filesystem with namespaces that are relevent on the mount level. Especially for non-vfs developers without detailed knowledge in this area this can be a potential source for bugs. Once the conversion to struct mnt_idmap is done all helpers down to the really low-level helpers will take a struct mnt_idmap argument instead of two namespace arguments. This way it becomes impossible to conflate the two eliminating the possibility of any bugs. All of the vfs and all filesystems only operate on struct mnt_idmap. Acked-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-01-13 12:49:20 +01:00
fs: make helpers idmap mount aware Extend some inode methods with an additional user namespace argument. A filesystem that is aware of idmapped mounts will receive the user namespace the mount has been marked with. This can be used for additional permission checking and also to enable filesystems to translate between uids and gids if they need to. We have implemented all relevant helpers in earlier patches. As requested we simply extend the exisiting inode method instead of introducing new ones. This is a little more code churn but it's mostly mechanical and doesnt't leave us with additional inode methods. Link: https://lore.kernel.org/r/20210121131959.646623-25-christian.brauner@ubuntu.com Cc: Christoph Hellwig <hch@lst.de> Cc: David Howells <dhowells@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
2021-01-21 14:19:43 +01:00
fuse: Add posix ACL support Add a new INIT flag, FUSE_POSIX_ACL, for negotiating ACL support with userspace. When it is set in the INIT response, ACL support will be enabled. ACL support also implies "default_permissions". When ACL support is enabled, the kernel will cache and have responsibility for enforcing ACLs. ACL xattrs will be passed to userspace, which is responsible for updating the ACLs in the filesystem, keeping the file mode in sync, and inheritance of default ACLs when new filesystem nodes are created. Signed-off-by: Seth Forshee <seth.forshee@canonical.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-08-29 08:46:37 -05:00
fs: pass dentry to set acl method The current way of setting and getting posix acls through the generic xattr interface is error prone and type unsafe. The vfs needs to interpret and fixup posix acls before storing or reporting it to userspace. Various hacks exist to make this work. The code is hard to understand and difficult to maintain in it's current form. Instead of making this work by hacking posix acls through xattr handlers we are building a dedicated posix acl api around the get and set inode operations. This removes a lot of hackiness and makes the codepaths easier to maintain. A lot of background can be found in [1]. Since some filesystem rely on the dentry being available to them when setting posix acls (e.g., 9p and cifs) they cannot rely on set acl inode operation. But since ->set_acl() is required in order to use the generic posix acl xattr handlers filesystems that do not implement this inode operation cannot use the handler and need to implement their own dedicated posix acl handlers. Update the ->set_acl() inode method to take a dentry argument. This allows all filesystems to rely on ->set_acl(). As far as I can tell all codepaths can be switched to rely on the dentry instead of just the inode. Note that the original motivation for passing the dentry separate from the inode instead of just the dentry in the xattr handlers was because of security modules that call security_d_instantiate(). This hook is called during d_instantiate_new(), d_add(), __d_instantiate_anon(), and d_splice_alias() to initialize the inode's security context and possibly to set security.* xattrs. Since this only affects security.* xattrs this is completely irrelevant for posix acls. Link: https://lore.kernel.org/all/20220801145520.1532837-1-brauner@kernel.org [1] Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2022-09-23 10:29:39 +02:00
fuse: Add posix ACL support Add a new INIT flag, FUSE_POSIX_ACL, for negotiating ACL support with userspace. When it is set in the INIT response, ACL support will be enabled. ACL support also implies "default_permissions". When ACL support is enabled, the kernel will cache and have responsibility for enforcing ACLs. ACL xattrs will be passed to userspace, which is responsible for updating the ACLs in the filesystem, keeping the file mode in sync, and inheritance of default ACLs when new filesystem nodes are created. Signed-off-by: Seth Forshee <seth.forshee@canonical.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-08-29 08:46:37 -05:00
fuse: fix bad inode Jan Kara's analysis of the syzbot report (edited): The reproducer opens a directory on FUSE filesystem, it then attaches dnotify mark to the open directory. After that a fuse_do_getattr() call finds that attributes returned by the server are inconsistent, and calls make_bad_inode() which, among other things does: inode->i_mode = S_IFREG; This then confuses dnotify which doesn't tear down its structures properly and eventually crashes. Avoid calling make_bad_inode() on a live inode: switch to a private flag on the fuse inode. Also add the test to ops which the bad_inode_ops would have caught. This bug goes back to the initial merge of fuse in 2.6.14... Reported-by: syzbot+f427adf9324b92652ccc@syzkaller.appspotmail.com Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Tested-by: Jan Kara <jack@suse.cz> Cc: <stable@vger.kernel.org>
2020-12-10 15:33:14 +01:00
fuse: fixes after adapting to new posix acl api This cycle we ported all filesystems to the new posix acl api. While looking at further simplifications in this area to remove the last remnants of the generic dummy posix acl handlers we realized that we regressed fuse daemons that don't set FUSE_POSIX_ACL but still make use of posix acls. With the change to a dedicated posix acl api interacting with posix acls doesn't go through the old xattr codepaths anymore and instead only relies the get acl and set acl inode operations. Before this change fuse daemons that don't set FUSE_POSIX_ACL were able to get and set posix acl albeit with two caveats. First, that posix acls aren't cached. And second, that they aren't used for permission checking in the vfs. We regressed that use-case as we currently refuse to retrieve any posix acls if they aren't enabled via FUSE_POSIX_ACL. So older fuse daemons would see a change in behavior. We can restore the old behavior in multiple ways. We could change the new posix acl api and look for a dedicated xattr handler and if we find one prefer that over the dedicated posix acl api. That would break the consistency of the new posix acl api so we would very much prefer not to do that. We could introduce a new ACL_*_CACHE sentinel that would instruct the vfs permission checking codepath to not call into the filesystem and ignore acls. But a more straightforward fix for v6.2 is to do the same thing that Overlayfs does and give fuse a separate get acl method for permission checking. Overlayfs uses this to express different needs for vfs permission lookup and acl based retrieval via the regular system call path as well. Let fuse do the same for now. This way fuse can continue to refuse to retrieve posix acls for daemons that don't set FUSE_POSXI_ACL for permission checking while allowing a fuse server to retrieve it via the usual system calls. In the future, we could extend the get acl inode operation to not just pass a simple boolean to indicate rcu lookup but instead make it a flag argument. Then in addition to passing the information that this is an rcu lookup to the filesystem we could also introduce a flag that tells the filesystem that this is a request from the vfs to use these acls for permission checking. Then fuse could refuse the get acl request for permission checking when the daemon doesn't have FUSE_POSIX_ACL set in the same get acl method. This would also help Overlayfs and allow us to remove the second method for it as well. But since that change is more invasive as we need to update the get acl inode operation for multiple filesystems we should not do this as a fix for v6.2. Instead we will do this for the v6.3 merge window. Fwiw, since posix acls are now always correctly translated in the new posix acl api we could also allow them to be used for daemons without FUSE_POSIX_ACL that are not mounted on the host. But this is behavioral change and again if dones should be done for v6.3. For now, let's just restore the original behavior. A nice side-effect of this change is that for fuse daemons with and without FUSE_POSIX_ACL the same code is used for posix acls in a backwards compatible way. This also means we can remove the legacy xattr handlers completely. We've also added comments to explain the expected behavior for daemons without FUSE_POSIX_ACL into the code. Fixes: 318e66856dde ("xattr: use posix acl api") Signed-off-by: Seth Forshee (Digital Ocean) <sforshee@kernel.org> Reviewed-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-01-20 12:55:04 +01:00
fuse: Add posix ACL support Add a new INIT flag, FUSE_POSIX_ACL, for negotiating ACL support with userspace. When it is set in the INIT response, ACL support will be enabled. ACL support also implies "default_permissions". When ACL support is enabled, the kernel will cache and have responsibility for enforcing ACLs. ACL xattrs will be passed to userspace, which is responsible for updating the ACLs in the filesystem, keeping the file mode in sync, and inheritance of default ACLs when new filesystem nodes are created. Signed-off-by: Seth Forshee <seth.forshee@canonical.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-08-29 08:46:37 -05:00
fuse: add a flag FUSE_SETXATTR_ACL_KILL_SGID to kill SGID When posix access ACL is set, it can have an effect on file mode and it can also need to clear SGID if. - None of caller's group/supplementary groups match file owner group. AND - Caller is not priviliged (No CAP_FSETID). As of now fuser server is responsible for changing the file mode as well. But it does not know whether to clear SGID or not. So add a flag FUSE_SETXATTR_ACL_KILL_SGID and send this info with SETXATTR to let file server know that sgid needs to be cleared as well. Reported-by: Luis Henriques <lhenriques@suse.de> Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2021-03-25 11:18:23 -04:00
fuse: Add posix ACL support Add a new INIT flag, FUSE_POSIX_ACL, for negotiating ACL support with userspace. When it is set in the INIT response, ACL support will be enabled. ACL support also implies "default_permissions". When ACL support is enabled, the kernel will cache and have responsibility for enforcing ACLs. ACL xattrs will be passed to userspace, which is responsible for updating the ACLs in the filesystem, keeping the file mode in sync, and inheritance of default ACLs when new filesystem nodes are created. Signed-off-by: Seth Forshee <seth.forshee@canonical.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-08-29 08:46:37 -05:00
posix_acl: make posix_acl_to_xattr() alloc the buffer Without exception all caller do that. So move the allocation into the helper. This reduces boilerplate and removes unnecessary error checking. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Link: https://patch.msgid.link/20260115122341.556026-1-mszeredi@redhat.com Signed-off-by: Christian Brauner <brauner@kernel.org>
2026-01-15 13:23:40 +01:00
fuse: Add posix ACL support Add a new INIT flag, FUSE_POSIX_ACL, for negotiating ACL support with userspace. When it is set in the INIT response, ACL support will be enabled. ACL support also implies "default_permissions". When ACL support is enabled, the kernel will cache and have responsibility for enforcing ACLs. ACL xattrs will be passed to userspace, which is responsible for updating the ACLs in the filesystem, keeping the file mode in sync, and inheritance of default ACLs when new filesystem nodes are created. Signed-off-by: Seth Forshee <seth.forshee@canonical.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-08-29 08:46:37 -05:00
posix_acl: make posix_acl_to_xattr() alloc the buffer Without exception all caller do that. So move the allocation into the helper. This reduces boilerplate and removes unnecessary error checking. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Link: https://patch.msgid.link/20260115122341.556026-1-mszeredi@redhat.com Signed-off-by: Christian Brauner <brauner@kernel.org>
2026-01-15 13:23:40 +01:00
fuse: Add posix ACL support Add a new INIT flag, FUSE_POSIX_ACL, for negotiating ACL support with userspace. When it is set in the INIT response, ACL support will be enabled. ACL support also implies "default_permissions". When ACL support is enabled, the kernel will cache and have responsibility for enforcing ACLs. ACL xattrs will be passed to userspace, which is responsible for updating the ACLs in the filesystem, keeping the file mode in sync, and inheritance of default ACLs when new filesystem nodes are created. Signed-off-by: Seth Forshee <seth.forshee@canonical.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-08-29 08:46:37 -05:00
posix_acl: make posix_acl_to_xattr() alloc the buffer Without exception all caller do that. So move the allocation into the helper. This reduces boilerplate and removes unnecessary error checking. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Link: https://patch.msgid.link/20260115122341.556026-1-mszeredi@redhat.com Signed-off-by: Christian Brauner <brauner@kernel.org>
2026-01-15 13:23:40 +01:00
fuse: Add posix ACL support Add a new INIT flag, FUSE_POSIX_ACL, for negotiating ACL support with userspace. When it is set in the INIT response, ACL support will be enabled. ACL support also implies "default_permissions". When ACL support is enabled, the kernel will cache and have responsibility for enforcing ACLs. ACL xattrs will be passed to userspace, which is responsible for updating the ACLs in the filesystem, keeping the file mode in sync, and inheritance of default ACLs when new filesystem nodes are created. Signed-off-by: Seth Forshee <seth.forshee@canonical.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-08-29 08:46:37 -05:00
posix_acl: make posix_acl_to_xattr() alloc the buffer Without exception all caller do that. So move the allocation into the helper. This reduces boilerplate and removes unnecessary error checking. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Link: https://patch.msgid.link/20260115122341.556026-1-mszeredi@redhat.com Signed-off-by: Christian Brauner <brauner@kernel.org>
2026-01-15 13:23:40 +01:00
fuse: Add posix ACL support Add a new INIT flag, FUSE_POSIX_ACL, for negotiating ACL support with userspace. When it is set in the INIT response, ACL support will be enabled. ACL support also implies "default_permissions". When ACL support is enabled, the kernel will cache and have responsibility for enforcing ACLs. ACL xattrs will be passed to userspace, which is responsible for updating the ACLs in the filesystem, keeping the file mode in sync, and inheritance of default ACLs when new filesystem nodes are created. Signed-off-by: Seth Forshee <seth.forshee@canonical.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-08-29 08:46:37 -05:00
fuse: fixes after adapting to new posix acl api This cycle we ported all filesystems to the new posix acl api. While looking at further simplifications in this area to remove the last remnants of the generic dummy posix acl handlers we realized that we regressed fuse daemons that don't set FUSE_POSIX_ACL but still make use of posix acls. With the change to a dedicated posix acl api interacting with posix acls doesn't go through the old xattr codepaths anymore and instead only relies the get acl and set acl inode operations. Before this change fuse daemons that don't set FUSE_POSIX_ACL were able to get and set posix acl albeit with two caveats. First, that posix acls aren't cached. And second, that they aren't used for permission checking in the vfs. We regressed that use-case as we currently refuse to retrieve any posix acls if they aren't enabled via FUSE_POSIX_ACL. So older fuse daemons would see a change in behavior. We can restore the old behavior in multiple ways. We could change the new posix acl api and look for a dedicated xattr handler and if we find one prefer that over the dedicated posix acl api. That would break the consistency of the new posix acl api so we would very much prefer not to do that. We could introduce a new ACL_*_CACHE sentinel that would instruct the vfs permission checking codepath to not call into the filesystem and ignore acls. But a more straightforward fix for v6.2 is to do the same thing that Overlayfs does and give fuse a separate get acl method for permission checking. Overlayfs uses this to express different needs for vfs permission lookup and acl based retrieval via the regular system call path as well. Let fuse do the same for now. This way fuse can continue to refuse to retrieve posix acls for daemons that don't set FUSE_POSXI_ACL for permission checking while allowing a fuse server to retrieve it via the usual system calls. In the future, we could extend the get acl inode operation to not just pass a simple boolean to indicate rcu lookup but instead make it a flag argument. Then in addition to passing the information that this is an rcu lookup to the filesystem we could also introduce a flag that tells the filesystem that this is a request from the vfs to use these acls for permission checking. Then fuse could refuse the get acl request for permission checking when the daemon doesn't have FUSE_POSIX_ACL set in the same get acl method. This would also help Overlayfs and allow us to remove the second method for it as well. But since that change is more invasive as we need to update the get acl inode operation for multiple filesystems we should not do this as a fix for v6.2. Instead we will do this for the v6.3 merge window. Fwiw, since posix acls are now always correctly translated in the new posix acl api we could also allow them to be used for daemons without FUSE_POSIX_ACL that are not mounted on the host. But this is behavioral change and again if dones should be done for v6.3. For now, let's just restore the original behavior. A nice side-effect of this change is that for fuse daemons with and without FUSE_POSIX_ACL the same code is used for posix acls in a backwards compatible way. This also means we can remove the legacy xattr handlers completely. We've also added comments to explain the expected behavior for daemons without FUSE_POSIX_ACL into the code. Fixes: 318e66856dde ("xattr: use posix acl api") Signed-off-by: Seth Forshee (Digital Ocean) <sforshee@kernel.org> Reviewed-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-01-20 12:55:04 +01:00
fuse: support idmapped ->set_acl It's just a matter of adjusting a permission check condition for S_ISGID flag. All the rest is already handled in the generic VFS code. Notice that this permission check is the analog of what we have in posix_acl_update_mode() generic helper, but fuse doesn't use this helper as on the kernel side we don't care about ensuring that POSIX ACL and CHMOD permissions are in sync as it is a responsibility of a userspace daemon to handle that. For the same reason we don't have a calls to posix_acl_chmod(), while most of other filesystem do. Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com> Reviewed-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2024-09-03 17:16:21 +02:00
fuse: add a flag FUSE_SETXATTR_ACL_KILL_SGID to kill SGID When posix access ACL is set, it can have an effect on file mode and it can also need to clear SGID if. - None of caller's group/supplementary groups match file owner group. AND - Caller is not priviliged (No CAP_FSETID). As of now fuser server is responsible for changing the file mode as well. But it does not know whether to clear SGID or not. So add a flag FUSE_SETXATTR_ACL_KILL_SGID and send this info with SETXATTR to let file server know that sgid needs to be cleared as well. Reported-by: Luis Henriques <lhenriques@suse.de> Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2021-03-25 11:18:23 -04:00
fuse: Add posix ACL support Add a new INIT flag, FUSE_POSIX_ACL, for negotiating ACL support with userspace. When it is set in the INIT response, ACL support will be enabled. ACL support also implies "default_permissions". When ACL support is enabled, the kernel will cache and have responsibility for enforcing ACLs. ACL xattrs will be passed to userspace, which is responsible for updating the ACLs in the filesystem, keeping the file mode in sync, and inheritance of default ACLs when new filesystem nodes are created. Signed-off-by: Seth Forshee <seth.forshee@canonical.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-08-29 08:46:37 -05:00
fuse: fixes after adapting to new posix acl api This cycle we ported all filesystems to the new posix acl api. While looking at further simplifications in this area to remove the last remnants of the generic dummy posix acl handlers we realized that we regressed fuse daemons that don't set FUSE_POSIX_ACL but still make use of posix acls. With the change to a dedicated posix acl api interacting with posix acls doesn't go through the old xattr codepaths anymore and instead only relies the get acl and set acl inode operations. Before this change fuse daemons that don't set FUSE_POSIX_ACL were able to get and set posix acl albeit with two caveats. First, that posix acls aren't cached. And second, that they aren't used for permission checking in the vfs. We regressed that use-case as we currently refuse to retrieve any posix acls if they aren't enabled via FUSE_POSIX_ACL. So older fuse daemons would see a change in behavior. We can restore the old behavior in multiple ways. We could change the new posix acl api and look for a dedicated xattr handler and if we find one prefer that over the dedicated posix acl api. That would break the consistency of the new posix acl api so we would very much prefer not to do that. We could introduce a new ACL_*_CACHE sentinel that would instruct the vfs permission checking codepath to not call into the filesystem and ignore acls. But a more straightforward fix for v6.2 is to do the same thing that Overlayfs does and give fuse a separate get acl method for permission checking. Overlayfs uses this to express different needs for vfs permission lookup and acl based retrieval via the regular system call path as well. Let fuse do the same for now. This way fuse can continue to refuse to retrieve posix acls for daemons that don't set FUSE_POSXI_ACL for permission checking while allowing a fuse server to retrieve it via the usual system calls. In the future, we could extend the get acl inode operation to not just pass a simple boolean to indicate rcu lookup but instead make it a flag argument. Then in addition to passing the information that this is an rcu lookup to the filesystem we could also introduce a flag that tells the filesystem that this is a request from the vfs to use these acls for permission checking. Then fuse could refuse the get acl request for permission checking when the daemon doesn't have FUSE_POSIX_ACL set in the same get acl method. This would also help Overlayfs and allow us to remove the second method for it as well. But since that change is more invasive as we need to update the get acl inode operation for multiple filesystems we should not do this as a fix for v6.2. Instead we will do this for the v6.3 merge window. Fwiw, since posix acls are now always correctly translated in the new posix acl api we could also allow them to be used for daemons without FUSE_POSIX_ACL that are not mounted on the host. But this is behavioral change and again if dones should be done for v6.3. For now, let's just restore the original behavior. A nice side-effect of this change is that for fuse daemons with and without FUSE_POSIX_ACL the same code is used for posix acls in a backwards compatible way. This also means we can remove the legacy xattr handlers completely. We've also added comments to explain the expected behavior for daemons without FUSE_POSIX_ACL into the code. Fixes: 318e66856dde ("xattr: use posix acl api") Signed-off-by: Seth Forshee (Digital Ocean) <sforshee@kernel.org> Reviewed-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-01-20 12:55:04 +01:00
fuse: Add posix ACL support Add a new INIT flag, FUSE_POSIX_ACL, for negotiating ACL support with userspace. When it is set in the INIT response, ACL support will be enabled. ACL support also implies "default_permissions". When ACL support is enabled, the kernel will cache and have responsibility for enforcing ACLs. ACL xattrs will be passed to userspace, which is responsible for updating the ACLs in the filesystem, keeping the file mode in sync, and inheritance of default ACLs when new filesystem nodes are created. Signed-off-by: Seth Forshee <seth.forshee@canonical.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-08-29 08:46:37 -05:00