Bug 2422727 (CVE-2025-40362)
| Summary: | CVE-2025-40362 kernel: Linux kernel (ceph): Incorrect authorization allows privilege escalation in multifs clusters | ||
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| Product: | [Other] Security Response | Reporter: | OSIDB Bzimport <bzimport> |
| Component: | vulnerability | Assignee: | Product Security DevOps Team <prodsec-dev> |
| Status: | NEW --- | QA Contact: | |
| Severity: | medium | Docs Contact: | |
| Priority: | medium | ||
| Version: | unspecified | Keywords: | Security |
| Target Milestone: | --- | ||
| Target Release: | --- | ||
| Hardware: | All | ||
| OS: | Linux | ||
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| Fixed In Version: | Doc Type: | --- | |
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A flaw was found in the Linux kernel, specifically within the Ceph filesystem. In a multi-filesystem Ceph cluster, the metadata server (MDS) authentication capabilities check did not properly validate the filesystem name. This oversight allowed the authentication capabilities intended for one filesystem to be incorrectly applied to another. A local user could exploit this vulnerability to bypass established file system permissions, thereby gaining unauthorized read and write access to files on a filesystem where their access should have been restricted.
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Story Points: | --- |
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| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
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In the Linux kernel, the following vulnerability has been resolved: ceph: fix multifs mds auth caps issue The mds auth caps check should also validate the fsname along with the associated caps. Not doing so would result in applying the mds auth caps of one fs on to the other fs in a multifs ceph cluster. The bug causes multiple issues w.r.t user authentication, following is one such example. Steps to Reproduce (on vstart cluster): 1. Create two file systems in a cluster, say 'fsname1' and 'fsname2' 2. Authorize read only permission to the user 'client.usr' on fs 'fsname1' $ceph fs authorize fsname1 client.usr / r 3. Authorize read and write permission to the same user 'client.usr' on fs 'fsname2' $ceph fs authorize fsname2 client.usr / rw 4. Update the keyring $ceph auth get client.usr >> ./keyring With above permssions for the user 'client.usr', following is the expectation. a. The 'client.usr' should be able to only read the contents and not allowed to create or delete files on file system 'fsname1'. b. The 'client.usr' should be able to read/write on file system 'fsname2'. But, with this bug, the 'client.usr' is allowed to read/write on file system 'fsname1'. See below. 5. Mount the file system 'fsname1' with the user 'client.usr' $sudo bin/mount.ceph usr@.fsname1=/ /kmnt_fsname1_usr/ 6. Try creating a file on file system 'fsname1' with user 'client.usr'. This should fail but passes with this bug. $touch /kmnt_fsname1_usr/file1 7. Mount the file system 'fsname1' with the user 'client.admin' and create a file. $sudo bin/mount.ceph admin@.fsname1=/ /kmnt_fsname1_admin $echo "data" > /kmnt_fsname1_admin/admin_file1 8. Try removing an existing file on file system 'fsname1' with the user 'client.usr'. This shoudn't succeed but succeeds with the bug. $rm -f /kmnt_fsname1_usr/admin_file1 For more information, please take a look at the corresponding mds/fuse patch and tests added by looking into the tracker mentioned below. v2: Fix a possible null dereference in doutc v3: Don't store fsname from mdsmap, validate against ceph_mount_options's fsname and use it v4: Code refactor, better warning message and fix possible compiler warning [ Slava.Dubeyko: "fsname check failed" -> "fsname mismatch" ]