Messages in this thread | | | From | (Peter Benie) | Subject | Semantics of append-only and immutible files | Date | Wed, 09 Feb 2000 14:22:29 +0000 |
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Some time ago I tried to use append-only immutible files and found the experience quite frustrating. I'll use append-only as an example of why.
Suppose you have syslogd writing to logfiles which are append-only. At some point, you will want to rotate those logfiles. Currently, this requires removing the append-only flag, rotating the file, and setting the flag again. Obviously, there is an opporunity for a race, which is Not Good (TM).
My attempts at using immutible files have also been complicated. I had to prepare the file inside a private directory since I wanted to change its contents. Then I set the immutible flag, but once the immutible flag was set, I couldn't move the file into its final location. This results in having to keep the extra directory for no particularly good reason.
The behaviour I want is for the append-only and immutible flags to only affect exactly those processes which do not have CAP_LINUX_IMMUTABLE set. This doesn't change the security properties of these flags since the processes that can override the flags are precisely those which could have removed the flag anyway.
If there are no objections, I'll construct a patch to do this.
Peter
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