Messages in this thread | | | Date | Wed, 23 Feb 2022 10:44:28 -0500 | Subject | Re: [PATCH v10 22/27] securityfs: Extend securityfs with namespacing support | From | Stefan Berger <> |
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On 2/23/22 03:14, Christian Brauner wrote: > On Tue, Feb 22, 2022 at 08:48:47PM -0500, Mimi Zohar wrote: >> On Tue, 2022-02-01 at 15:37 -0500, Stefan Berger wrote: >>> Enable multiple instances of securityfs by keying each instance with a >>> pointer to the user namespace it belongs to. >>> >>> Since we do not need the pinning of the filesystem for the virtualization >> ^namespacing case >> >>> case, limit the usage of simple_pin_fs() and simpe_release_fs() to the >> ^simple_release_fs >> >>> case when the init_user_ns is active. This simplifies the cleanup for the >>> virtualization case where usage of securityfs_remove() to free dentries >> ^namespacing >> >>> is therefore not needed anymore. >>> >>> For the initial securityfs, i.e. the one mounted in the host userns mount, >>> nothing changes. The rules for securityfs_remove() are as before and it is >>> still paired with securityfs_create(). Specifically, a file created via >>> securityfs_create_dentry() in the initial securityfs mount still needs to >>> be removed by a call to securityfs_remove(). Creating a new dentry in the >>> initial securityfs mount still pins the filesystem like it always did. >>> Consequently, the initial securityfs mount is not destroyed on >>> umount/shutdown as long as at least one user of it still has dentries that >>> it hasn't removed with a call to securityfs_remove(). >>> >>> Prevent mounting of an instance of securityfs in another user namespace >>> than it belongs to. Also, prevent accesses to files and directories by >>> a user namespace that is neither the user namespace it belongs to >>> nor an ancestor of the user namespace that the instance of securityfs >>> belongs to. Do not prevent access if securityfs was bind-mounted and >>> therefore the init_user_ns is the owning user namespace. >>> >>> Suggested-by: Christian Brauner <brauner@kernel.org> >>> Signed-off-by: Stefan Berger <stefanb@linux.ibm.com> >>> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com> >> Christian, I understand that "[PATCH v10 23/27] ima: Setup securityfs >> for IMA namespace" needs to be deferred, but is there a reason for >> deferring "[PATCH v10 22/27] securityfs: Extend securityfs with >> namespacing support"? As the securityfs patches are really >> independent of IMA namespacing, I would have thought "[PATCH v10 >> 04/27] securityfs: rework dentry creation" and this patch should be co- >> located at the beginning of the patch set. > It felt more natural to me to defer it until the end but I have no > strong thoughts on this as of right now. Since Stefan has mentioned > moving this earlier already himself and you seem to agree as well, feel > free to do so.
I'll move it after 'securityfs: rework dentry creation' if that's ok.
Stefan
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