CVE-2021-46975
Public on 2024-02-27
Modified on 2024-03-18
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.
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.
Severity
CVSS v3 Base Score
See breakdown
Affected Packages
Platform | Package | Release Date | Advisory | Status |
---|---|---|---|---|
Amazon Linux 1 | kernel | No Fix Planned | ||
Amazon Linux 2 - Core | kernel | Pending Fix | ||
Amazon Linux 2 - Kernel-5.10 Extra | kernel | Pending Fix | ||
Amazon Linux 2 - Kernel-5.4 Extra | kernel | Pending Fix | ||
Amazon Linux 2 - Kernel-5.15 Extra | kernel | Not Affected | ||
Amazon Linux 2023 | kernel | Not Affected |
CVSS Scores
Score Type | Score | Vector | |
---|---|---|---|
Amazon Linux | CVSSv3 | 5.5 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N |