CVE-2021-47010 net: Only allow init netns to set default tcp cong to a restricted algo

2024-02-2808:13:29

Linux

www.cve.org

linux kernel

vulnerability resolved

init netns

restricted algorithm

netns-safe

unintended side-effect

net namespace

bug

github

cve

AI Score

6.5

Confidence

High

EPSS

Percentile

10.3%

JSON

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

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "net/ipv4/tcp_cong.c"
    ],
    "versions": [
      {
        "version": "6670e1524477",
        "lessThan": "992de06308d9",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "6670e1524477",
        "lessThan": "9884f745108f",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "6670e1524477",
        "lessThan": "6c1ea8bee75d",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "6670e1524477",
        "lessThan": "efe1532a6e1a",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "6670e1524477",
        "lessThan": "e7d7bedd507b",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "6670e1524477",
        "lessThan": "8d432592f30f",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "net/ipv4/tcp_cong.c"
    ],
    "versions": [
      {
        "version": "4.15",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "4.15",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "4.19.191",
        "lessThanOrEqual": "4.19.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.4.119",
        "lessThanOrEqual": "5.4.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.10.37",
        "lessThanOrEqual": "5.10.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.11.21",
        "lessThanOrEqual": "5.11.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.12.4",
        "lessThanOrEqual": "5.12.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.13",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]