A vulnerability in DavFS2 allows local users to gain root privileges.
| Package | Arch | Vulnerable | Unaffected |
|---|---|---|---|
| net-fs/davfs2 | * | < 1.5.2 | >= 1.5.2 |
DavFS2 is a file system driver that allows you to mount a WebDAV server as a local disk drive.
DavFS2 installs “/usr/sbin/mount.davfs” as setuid root. This utility uses “system()” to call “/sbin/modprobe”.
While the call to “modprobe” itself cannot be manipulated, a local authenticated user can set the “MODPROBE_OPTIONS” environment variable to pass a user controlled path, allowing the loading of an arbitrary kernel module.
A local user could gain root privileges.
The system administrator should ensure that all modules the “mount.davfs” utility tries to load are loaded upon system boot before any local user can call the utility.
An additional defense measure can be implemented by enabling the Linux kernel module signing feature. This assists in the prevention of arbitrary modules being loaded.
All DavFS2 users should upgrade to the latest version:
# emerge --sync # emerge --ask --oneshot --verbose ">=net-fs/davfs2-1.5.2"
Davfs2 and the lvmcreate_initrd script (included in the lvm-user package) are both vulnerable to symlink attacks, potentially allowing a local user to overwrite arbitrary files with the rights of the user running them.
| Package | Arch | Vulnerable | Unaffected |
|---|---|---|---|
| net-fs/davfs2 | * | < 0.2.2-r1 | >= 0.2.2-r1 |
| sys-fs/lvm-user | * | < 1.0.7-r2 | >= 1.0.7-r2 |
Davfs2 is a file system driver that allows you to mount a WebDAV server as a local disk drive. lvm-user is a package providing userland utilities for LVM (Logical Volume Management) 1.x features.
Florian Schilhabel from the Gentoo Linux Security Audit Team found that Davfs2 insecurely created .pid files in /tmp. Furthermore, Trustix Secure Linux found that the lvmcreate_initrd script, included in the lvm-user Gentoo package, also creates temporary files in world-writeable directories with predictable names.
A local attacker could create symbolic links in the temporary files directory, pointing to a valid file somewhere on the filesystem. When Davfs2 or lvmcreate_initrd is called, this would result in the file being overwritten with the rights of the user running the software, which could be the root user.
There is no known workaround at this time.
All Davfs2 users should upgrade to the latest version:
# emerge --sync # emerge --ask --oneshot --verbose ">=net-fs/davfs2-0.2.2-r1"
All lvm-user users should upgrade to the latest version:
# emerge --sync # emerge --ask --oneshot --verbose ">=sys-fs/lvm-user-1.0.7-r2"