Headline
CVE-2023-5369
Before correction, the copy_file_range system call checked only for the CAP_READ and CAP_WRITE capabilities on the input and output file descriptors, respectively. Using an offset is logically equivalent to seeking, and the system call must additionally require the CAP_SEEK capability.
This incorrect privilege check enabled sandboxed processes with only read or write but no seek capability on a file descriptor to read data from or write data to an arbitrary location within the file corresponding to that file descriptor.
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 ============================================================================= FreeBSD-SA-23:13.capsicum Security Advisory The FreeBSD Project Topic: copy_file_range insufficient capability rights check Category: core Module: capsicum Announced: 2023-10-03 Credits: David Chisnall Affects: FreeBSD 13.2 Corrected: 2023-10-02 16:00:27 UTC (stable/13, 13.2-STABLE) 2023-10-03 21:24:41 UTC (releng/13.2, 13.2-RELEASE-p4) CVE Name: CVE-2023-5369 For general information regarding FreeBSD Security Advisories, including descriptions of the fields above, security branches, and the following sections, please visit . I. Background Capsicum is a lightweight OS capability and sandbox framework. It provides two kernel primatives, capability mode and capabilities. Capabilities limit operations that can be performed on file descriptors. copy_file_range is a system call that performs a kernel copy of a byte range from one file to another or within one file. copy_file_range accepts optional pointers to offsets for the input and output file descriptors. II. Problem Description The syscall checked only for the CAP_READ and CAP_WRITE capabilities on the input and output file descriptors, respectively. Using an offset is logically equivalent to seeking, and the syscall must additionally require the CAP_SEEK capability. III. Impact A sandboxed process with only read or write but no seek capability on a file descriptor may be able to read data from or write data to an arbitrary location within the file corresponding to that file descriptor. IV. Workaround No workaround is available. V. Solution Upgrade your vulnerable system to a supported FreeBSD stable or release / security branch (releng) dated after the correction date, and reboot. Perform one of the following: 1) To update your vulnerable system via a binary patch: Systems running a RELEASE version of FreeBSD on the amd64, i386, or (on FreeBSD 13 and later) arm64 platforms can be updated via the freebsd-update(8) utility: # freebsd-update fetch # freebsd-update install # shutdown -r +10min “Rebooting for a security update” 2) To update your vulnerable system via a source code patch: The following patches have been verified to apply to the applicable FreeBSD release branches. a) Download the relevant patch from the location below, and verify the detached PGP signature using your PGP utility. # fetch https://security.FreeBSD.org/patches/SA-23:13/capsicum.patch # fetch https://security.FreeBSD.org/patches/SA-23:13/capsicum.patch.asc # gpg --verify capsicum.patch.asc b) Apply the patch. Execute the following commands as root: # cd /usr/src # patch < /path/to/patch c) Recompile your kernel as described in and reboot the system. VI. Correction details This issue is corrected by the corresponding Git commit hash or Subversion revision number in the following stable and release branches: Branch/path Hash Revision - ------------------------------------------------------------------------- stable/13/ 3f0ce63828dc stable/13-n256458 releng/13.2/ 2d23f6c33431 releng/13.2-n254636 - ------------------------------------------------------------------------- Run the following command to see which files were modified by a particular commit: # git show --stat Or visit the following URL, replacing NNNNNN with the hash: To determine the commit count in a working tree (for comparison against nNNNNNN in the table above), run: # git rev-list --count --first-parent HEAD VII. References The latest revision of this advisory is available at -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEEthUnfoEIffdcgYM7bljekB8AGu8FAmUclU0ACgkQbljekB8A Gu/a3Q//aXO1+HdImFnqAzKEto8E97DEv6vB2HUZAoxrmwSX9VNjkrIo9Z9+LRyL q7WXMcok1OPQCCE3ad+g05eqXwnmJ55CpToP/jEXrOOZRDInK0Z5owZbwVpmyAmW zF/+xoEjcw90H7ReIQQ3+TNGDf025tCoXlTQKdzWtNN6BcY3px4zuDYHPUKgMwSv XJDrjYWBzBede00CnlolwmsBorjvZvRMfllTIpiVTlmtD73s+sRDI7rc768MY0RZ gCplCL9S9EkIGL8XJhDWB2+TsG7nvwrUII5M2u0Db252IK7nmgty4l03PtYotx4p jH/a3oXWKeqExGHJaqNcaUwS6xdu+pvMRuJgY4mH6rd+uvOMbC5jvac3FopSlmXq aVIctA2LCRomyYmVDsWXIGLcBT5cAOhsqkrw+JE0kA/k2Pl6NDNK7HNgo6Fj01TR lVf91A1mTsDJxfymU4SWB/KGgImAnR9e7gHUo4gLZCNyYXvcnFa/ntHoswNZ+12L e/b4+PnHts2X4/+I4K6qdF522yzF/vpyF6UjfwAGtT6qmbmGyW9VbDcn6TIL9I3p IDKJCWeHPBfyspWua2hCUIi3/EwpSFvIECPad3hFT6cej1pZ6hfJt8XT0ma82QGp ocbh3tb3E1phSGvgZitk8J0oyWDehuck3YfZ+6nHMwzPBgmr6Lo= =lS69 -----END PGP SIGNATURE-----