| From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2021-47010: net: Only allow init netns to set default tcp cong to a restricted algo |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| net: Only allow init netns to set default tcp cong to a restricted algo |
| |
| tcp_set_default_congestion_control() is netns-safe in that it writes |
| to &net->ipv4.tcp_congestion_control, but it also sets |
| ca->flags |= TCP_CONG_NON_RESTRICTED which is not namespaced. |
| This has the unintended side-effect of changing the global |
| net.ipv4.tcp_allowed_congestion_control sysctl, despite the fact that it |
| is read-only: 97684f0970f6 ("net: Make tcp_allowed_congestion_control |
| readonly in non-init netns") |
| |
| Resolve this netns "leak" by only allowing the init netns to set the |
| default algorithm to one that is restricted. This restriction could be |
| removed if tcp_allowed_congestion_control were namespace-ified in the |
| future. |
| |
| This bug was uncovered with |
| https://github.com/JonathonReinhart/linux-netns-sysctl-verify |
| |
| The Linux kernel CVE team has assigned CVE-2021-47010 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 4.15 with commit 6670e152447732ba90626f36dfc015a13fbf150e and fixed in 4.19.191 with commit 992de06308d9a9584d59b96d294ac676f924e437 |
| Issue introduced in 4.15 with commit 6670e152447732ba90626f36dfc015a13fbf150e and fixed in 5.4.119 with commit 9884f745108f7d25b189bbcd6754e284fb29ab68 |
| Issue introduced in 4.15 with commit 6670e152447732ba90626f36dfc015a13fbf150e and fixed in 5.10.37 with commit 6c1ea8bee75df8fe2184a50fcd0f70bf82986f42 |
| Issue introduced in 4.15 with commit 6670e152447732ba90626f36dfc015a13fbf150e and fixed in 5.11.21 with commit efe1532a6e1a8e3c343d04fff510f0ed80328f9c |
| Issue introduced in 4.15 with commit 6670e152447732ba90626f36dfc015a13fbf150e and fixed in 5.12.4 with commit e7d7bedd507bb732e600403b7a96f9fe48d0ca31 |
| Issue introduced in 4.15 with commit 6670e152447732ba90626f36dfc015a13fbf150e and fixed in 5.13 with commit 8d432592f30fcc34ef5a10aac4887b4897884493 |
| |
| 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-2021-47010 |
| 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: |
| net/ipv4/tcp_cong.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/992de06308d9a9584d59b96d294ac676f924e437 |
| https://git.kernel.org/stable/c/9884f745108f7d25b189bbcd6754e284fb29ab68 |
| https://git.kernel.org/stable/c/6c1ea8bee75df8fe2184a50fcd0f70bf82986f42 |
| https://git.kernel.org/stable/c/efe1532a6e1a8e3c343d04fff510f0ed80328f9c |
| https://git.kernel.org/stable/c/e7d7bedd507bb732e600403b7a96f9fe48d0ca31 |
| https://git.kernel.org/stable/c/8d432592f30fcc34ef5a10aac4887b4897884493 |
