CVE-2025-71304: smack: /smack/doi: accept previously used values

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

From: Greg Kroah-Hartman <gregkh@kernel.org>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

smack: /smack/doi: accept previously used values

Writing to /smack/doi a value that has ever been
written there in the past disables networking for
non-ambient labels.
E.g.

    # cat /smack/doi
    3
    # netlabelctl -p cipso list
    Configured CIPSO mappings (1)
     DOI value : 3
       mapping type : PASS_THROUGH
    # netlabelctl -p map list
    Configured NetLabel domain mappings (3)
     domain: "_" (IPv4)
       protocol: UNLABELED
     domain: DEFAULT (IPv4)
       protocol: CIPSO, DOI = 3
     domain: DEFAULT (IPv6)
       protocol: UNLABELED

    # cat /smack/ambient
    _
    # cat /proc/$$/attr/smack/current
    _
    # ping -c1 10.1.95.12
    64 bytes from 10.1.95.12: icmp_seq=1 ttl=64 time=0.964 ms
    # echo foo >/proc/$$/attr/smack/current
    # ping -c1 10.1.95.12
    64 bytes from 10.1.95.12: icmp_seq=1 ttl=64 time=0.956 ms
    unknown option 86

    # echo 4 >/smack/doi
    # echo 3 >/smack/doi
!>  [  214.050395] smk_cipso_doi:691 cipso add rc = -17
    # echo 3 >/smack/doi
!>  [  249.402261] smk_cipso_doi:678 remove rc = -2
!>  [  249.402261] smk_cipso_doi:691 cipso add rc = -17

    # ping -c1 10.1.95.12
!!> ping: 10.1.95.12: Address family for hostname not supported

    # echo _ >/proc/$$/attr/smack/current
    # ping -c1 10.1.95.12
    64 bytes from 10.1.95.12: icmp_seq=1 ttl=64 time=0.617 ms

This happens because Smack keeps decommissioned DOIs,
fails to re-add them, and consequently refuses to add
the “default” domain map:

    # netlabelctl -p cipso list
    Configured CIPSO mappings (2)
     DOI value : 3
       mapping type : PASS_THROUGH
     DOI value : 4
       mapping type : PASS_THROUGH
    # netlabelctl -p map list
    Configured NetLabel domain mappings (2)
     domain: "_" (IPv4)
       protocol: UNLABELED
!>  (no ipv4 map for default domain here)
     domain: DEFAULT (IPv6)
       protocol: UNLABELED

Fix by clearing decommissioned DOI definitions and
serializing concurrent DOI updates with a new lock.

Also:
- allow /smack/doi to live unconfigured, since
  adding a map (netlbl_cfg_cipsov4_map_add) may fail.
  CIPSO_V4_DOI_UNKNOWN(0) indicates the unconfigured DOI
- add new DOI before removing the old default map,
  so the old map remains if the add fails

(2008-02-04, Casey Schaufler)

The Linux kernel CVE team has assigned CVE-2025-71304 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 2.6.25 with commit e114e473771c848c3cfec05f0123e70f1cdbdc99 and fixed in 5.10.252 with commit eb718a3c8181ada679340db34cd61bce48e44749
	Issue introduced in 2.6.25 with commit e114e473771c848c3cfec05f0123e70f1cdbdc99 and fixed in 5.15.202 with commit 6ec091c5c7eeabd249a7c46813cad1e9f555f859
	Issue introduced in 2.6.25 with commit e114e473771c848c3cfec05f0123e70f1cdbdc99 and fixed in 6.1.165 with commit 199452f22d2f74b897fe826f81ec402b0a8461a0
	Issue introduced in 2.6.25 with commit e114e473771c848c3cfec05f0123e70f1cdbdc99 and fixed in 6.6.128 with commit 1c7ee23dfcd18d80770d8f90f2ab5bb1b2bfd8a3
	Issue introduced in 2.6.25 with commit e114e473771c848c3cfec05f0123e70f1cdbdc99 and fixed in 6.12.75 with commit f8071500177f38cff38892bd85ac631cc6e010b2
	Issue introduced in 2.6.25 with commit e114e473771c848c3cfec05f0123e70f1cdbdc99 and fixed in 6.18.14 with commit 5a247a84de0ba44edbbd6be851c8a6b2aa60ff85
	Issue introduced in 2.6.25 with commit e114e473771c848c3cfec05f0123e70f1cdbdc99 and fixed in 6.19.4 with commit 8beebb8ad9a003f978e53b06237986588223e15e
	Issue introduced in 2.6.25 with commit e114e473771c848c3cfec05f0123e70f1cdbdc99 and fixed in 7.0 with commit 33d589ed60ae433b483761987b85e0d24e54584e

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2025-71304
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	security/smack/smackfs.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/eb718a3c8181ada679340db34cd61bce48e44749
	https://git.kernel.org/stable/c/6ec091c5c7eeabd249a7c46813cad1e9f555f859
	https://git.kernel.org/stable/c/199452f22d2f74b897fe826f81ec402b0a8461a0
	https://git.kernel.org/stable/c/1c7ee23dfcd18d80770d8f90f2ab5bb1b2bfd8a3
	https://git.kernel.org/stable/c/f8071500177f38cff38892bd85ac631cc6e010b2
	https://git.kernel.org/stable/c/5a247a84de0ba44edbbd6be851c8a6b2aa60ff85
	https://git.kernel.org/stable/c/8beebb8ad9a003f978e53b06237986588223e15e
	https://git.kernel.org/stable/c/33d589ed60ae433b483761987b85e0d24e54584e