GHSA-qjh3-4j3h-vmwp

Summary

The issue was identified during Quarkslab's security audit on the Certificate Revocation List (CRL) based revocation check feature. After retrieving the CRL, notation-go attempts to update the CRL cache using the os.Rename method. However, this operation may fail due to operating system-specific limitations, particularly when the source and destination paths are on different mount points. This failure could lead to an unexpected program termination.

Details

In method crl.(*FileCache).Set, a temporary file is created in the OS dedicated area (like /tmp for, usually, Linux/Unix). The file is written and then it is tried to move it to the dedicated notation cache directory thanks os.Rename. As specified in Go documentation, OS specific restriction may apply. When used with Linux OS, it is relying on rename syscall from the libc and as per the documentation, moving a file to a different mountpoint raises an EXDEV error, interpreted as Cross device link not permitted error. Some Linux distribution, like RedHat use a dedicated filesystem (tmpfs), mounted on a specific mountpoint (usually /tmp) for temporary files. When using such OS, revocation check based on CRL will repeatedly crash notation.

PoC

1. Ensure that the temporary file storage area (e.g., /tmp) is mounted on a different mount point than the user's 'notation' cache directory.
2. Either disable the Online Certificate Status Protocol (OCSP) revocation check, or utilize certificates that exclusively support Certificate Revocation Lists (CRLs) for revocation check.
3. Try to verify a previously generated signature using the 'notation' tool.

Impact

The signature verification process is aborted as process crashes.

Remediation

The cache file should be created, written, then copied to the wanted final location, and finally removed. Additionally, this error shouldn't lead to a crash as it is not fatal and shouldn't prevent the rest of the program to properly continue