Time-of-check to time-of-use: Difference between revisions

Revision as of 19:59, 29 May 2012

Revision as of 20:00, 29 May 2012

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[[File locking]] is a common technique for preventing race conditions for a single file, but it does not extend to the file system namespace and other metadata, and cannot prevent TOCTTOU race conditions.

For setuid binaries a possible solution is to use the <code>seteuid()</code> system call to change the effective user and then perform the <code>open()</code>. Differences in <code>set*ui()</code> between operating systems might be problematic, but are well explained in <ref>[http://www.cs.berkeley.edu/~daw/papers/setuid-usenix02.pdf Chen, Hao; Wagner, David; Dean, Drew; "Setuid Demystified"]</ref>.

== References ==