| From bippy-c298863b1525 Mon Sep 17 00:00:00 2001 |
| From: gregkh@kernel.org |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2021-46975: netfilter: conntrack: Make global sysctls readonly in non-init netns |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| netfilter: conntrack: Make global sysctls readonly in non-init netns |
| |
| These sysctls point to global variables: |
| - NF_SYSCTL_CT_MAX (&nf_conntrack_max) |
| - NF_SYSCTL_CT_EXPECT_MAX (&nf_ct_expect_max) |
| - NF_SYSCTL_CT_BUCKETS (&nf_conntrack_htable_size_user) |
| |
| Because their data pointers are not updated to point to per-netns |
| structures, they must be marked read-only in a non-init_net ns. |
| Otherwise, changes in any net namespace are reflected in (leaked into) |
| all other net namespaces. This problem has existed since the |
| introduction of net namespaces. |
| |
| The current logic marks them read-only only if the net namespace is |
| owned by an unprivileged user (other than init_user_ns). |
| |
| Commit d0febd81ae77 ("netfilter: conntrack: re-visit sysctls in |
| unprivileged namespaces") "exposes all sysctls even if the namespace is |
| unpriviliged." Since we need to mark them readonly in any case, we can |
| forego the unprivileged user check altogether. |
| |
| The Linux kernel CVE team has assigned CVE-2021-46975 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.7 with commit d0febd81ae77 and fixed in 4.9.269 with commit da50f56e826e |
| Issue introduced in 5.7 with commit d0febd81ae77 and fixed in 4.14.233 with commit 68122479c128 |
| Issue introduced in 5.7 with commit d0febd81ae77 and fixed in 4.19.191 with commit 9b288479f7a9 |
| Issue introduced in 5.7 with commit d0febd81ae77 and fixed in 5.4.120 with commit baea536cf51f |
| Issue introduced in 5.7 with commit d0febd81ae77 and fixed in 5.10.35 with commit d3598eb3915c |
| Issue introduced in 5.7 with commit d0febd81ae77 and fixed in 5.11.19 with commit fbf85a34ce17 |
| Issue introduced in 5.7 with commit d0febd81ae77 and fixed in 5.12.2 with commit 671c54ea8c7f |
| Issue introduced in 5.7 with commit d0febd81ae77 and fixed in 5.13 with commit 2671fa4dc010 |
| |
| Please see https://www.kernel.org or 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-2021-46975 |
| 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/netfilter/nf_conntrack_standalone.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/da50f56e826e1db141693297afb99370ebc160dd |
| https://git.kernel.org/stable/c/68122479c128a929f8f7bdd951cfdc8dd0e75b8f |
| https://git.kernel.org/stable/c/9b288479f7a901a14ce703938596438559d7df55 |
| https://git.kernel.org/stable/c/baea536cf51f8180ab993e374cb134b5edad25e2 |
| https://git.kernel.org/stable/c/d3598eb3915cc0c0d8cab42f4a6258ff44c4033e |
| https://git.kernel.org/stable/c/fbf85a34ce17c4cf0a37ee253f4c582bbfb8231b |
| https://git.kernel.org/stable/c/671c54ea8c7ff47bd88444f3fffb65bf9799ce43 |
| https://git.kernel.org/stable/c/2671fa4dc0109d3fb581bc3078fdf17b5d9080f6 |
