cve-2020-16120
Vulnerability from cvelistv5
Published
2021-02-10 19:45
Modified
2024-09-16 18:49
Severity ?
5.1 (Medium) - CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Summary
Overlayfs did not properly perform permission checking when copying up files in an overlayfs and could be exploited from within a user namespace, if, for example, unprivileged user namespaces were allowed. It was possible to have a file not readable by an unprivileged user to be copied to a mountpoint controlled by the user, like a removable device. This was introduced in kernel version 4.19 by commit d1d04ef ("ovl: stack file ops"). This was fixed in kernel version 5.8 by commits 56230d9 ("ovl: verify permissions in ovl_path_open()"), 48bd024 ("ovl: switch to mounter creds in readdir") and 05acefb ("ovl: check permission to open real file"). Additionally, commits 130fdbc ("ovl: pass correct flags for opening real directory") and 292f902 ("ovl: call secutiry hook in ovl_real_ioctl()") in kernel 5.8 might also be desired or necessary. These additional commits introduced a regression in overlay mounts within user namespaces which prevented access to files with ownership outside of the user namespace. This regression was mitigated by subsequent commit b6650da ("ovl: do not fail because of O_NOATIMEi") in kernel 5.11.
References
security@ubuntu.comhttps://git.kernel.org/linus/05acefb4872dae89e772729efb194af754c877e8Patch, Third Party Advisory
security@ubuntu.comhttps://git.kernel.org/linus/48bd024b8a40d73ad6b086de2615738da0c7004fPatch, Third Party Advisory
security@ubuntu.comhttps://git.kernel.org/linus/56230d956739b9cb1cbde439d76227d77979a04dPatch, Third Party Advisory
security@ubuntu.comhttps://git.kernel.org/linus/b6650dab404c701d7fe08a108b746542a934da84Patch, Third Party Advisory
security@ubuntu.comhttps://git.kernel.org/linus/d1d04ef8572bc8c22265057bd3d5a79f223f8f52Patch, Third Party Advisory
security@ubuntu.comhttps://launchpad.net/bugs/1894980Issue Tracking, Patch, Third Party Advisory
security@ubuntu.comhttps://launchpad.net/bugs/1900141Issue Tracking, Third Party Advisory
security@ubuntu.comhttps://ubuntu.com/USN-4576-1Third Party Advisory
security@ubuntu.comhttps://ubuntu.com/USN-4577-1Third Party Advisory
security@ubuntu.comhttps://ubuntu.com/USN-4578-1Third Party Advisory
security@ubuntu.comhttps://www.openwall.com/lists/oss-security/2020/10/14/2Mailing List, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/linus/05acefb4872dae89e772729efb194af754c877e8Patch, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/linus/48bd024b8a40d73ad6b086de2615738da0c7004fPatch, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/linus/56230d956739b9cb1cbde439d76227d77979a04dPatch, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/linus/b6650dab404c701d7fe08a108b746542a934da84Patch, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/linus/d1d04ef8572bc8c22265057bd3d5a79f223f8f52Patch, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://launchpad.net/bugs/1894980Issue Tracking, Patch, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://launchpad.net/bugs/1900141Issue Tracking, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://ubuntu.com/USN-4576-1Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://ubuntu.com/USN-4577-1Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://ubuntu.com/USN-4578-1Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://www.openwall.com/lists/oss-security/2020/10/14/2Mailing List, Third Party Advisory
Impacted products
Vendor Product Version
Linux kernel Linux kernel Version: 5.11-stable   < 5.11.0
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         sourceIdentifier: "security@ubuntu.com",
         vulnStatus: "Modified",
         weaknesses: "[{\"source\": \"security@ubuntu.com\", \"type\": \"Secondary\", \"description\": [{\"lang\": \"en\", \"value\": \"CWE-266\"}]}, {\"source\": \"nvd@nist.gov\", \"type\": \"Primary\", \"description\": [{\"lang\": \"en\", \"value\": \"NVD-CWE-Other\"}]}]",
      },
      nvd: "{\"cve\":{\"id\":\"CVE-2020-16120\",\"sourceIdentifier\":\"security@ubuntu.com\",\"published\":\"2021-02-10T20:15:15.150\",\"lastModified\":\"2024-11-21T05:06:48.070\",\"vulnStatus\":\"Modified\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"Overlayfs did not properly perform permission checking when copying up files in an overlayfs and could be exploited from within a user namespace, if, for example, unprivileged user namespaces were allowed. It was possible to have a file not readable by an unprivileged user to be copied to a mountpoint controlled by the user, like a removable device. This was introduced in kernel version 4.19 by commit d1d04ef (\\\"ovl: stack file ops\\\"). This was fixed in kernel version 5.8 by commits 56230d9 (\\\"ovl: verify permissions in ovl_path_open()\\\"), 48bd024 (\\\"ovl: switch to mounter creds in readdir\\\") and 05acefb (\\\"ovl: check permission to open real file\\\"). Additionally, commits 130fdbc (\\\"ovl: pass correct flags for opening real directory\\\") and 292f902 (\\\"ovl: call secutiry hook in ovl_real_ioctl()\\\") in kernel 5.8 might also be desired or necessary. These additional commits introduced a regression in overlay mounts within user namespaces which prevented access to files with ownership outside of the user namespace. This regression was mitigated by subsequent commit b6650da (\\\"ovl: do not fail because of O_NOATIMEi\\\") in kernel 5.11.\"},{\"lang\":\"es\",\"value\":\"Overlayfs no realizaba apropiadamente la comprobación de permisos al copiar archivos en un overlayfs y podría explotarse desde dentro de un espacio de nombre de usuario, si, por ejemplo, se permitieran espacios de nombre de usuario sin privilegios.&#xa0;Era posible tener un archivo no legible por un usuario sin privilegios para ser copiado en un punto de montaje controlado por el usuario, como un dispositivo extraíble.&#xa0;Esto fue introducido en la versión 4.19 del kernel mediante la commit d1d04ef (\\\"ovl: stack file ops\\\").&#xa0;Esto se corrigió en la versión 5.8 del kernel mediante las commits 56230d9 (\\\"ovl: verify permissions in ovl_path_open()\\\"), 48bd024 (\\\"ovl: switch to mounter creds in readdir\\\" y 05acefb (\\\"ovl: check permission to open real file\\\") .&#xa0;Además, confirma 130fdbc (\\\"ovl: pass correct 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   },
}


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  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
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