Changes between Version 3 and Version 4 of WikiStart


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Timestamp:
Jul 27, 2005, 10:09:56 AM (14 years ago)
Author:
jtv
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  • WikiStart

    v3 v4  
    108108The installation procedure creates a directory ''/var/lib/swapspace'', which must be accessible to the system's superuser (root) __only__; granting any kind of access for this directory to an untrusted user is likely to constitute a serious security hole.
    109109
    110 According to the Filesystem Hierarchy Standard, other appropriate places for
    111 this kind of file might be ''/var/tmp'' or ''/var/run''.  The former was not deemed appropriate because it is accessible to all users, and the latter because most system administrators would probably expect it to occupy very little space and may confine it to a partition that isn't large enough to hold useful swap space.
     110According to the [http://www.pathname.com/fhs/ Filesystem Hierarchy Standard], other appropriate places for this kind of file might be ''/var/tmp'' or ''/var/run''.  The former was not deemed appropriate because it is accessible to all users, and the latter because most system administrators would probably expect it to occupy very little space and may confine it to a partition that isn't large enough to hold useful swap space.
    112111
    113112Also, files in ''/var/lib'' survive reboots whereas those in ''/var/tmp'' and ''/var/run'' need not.  Obviously any data in swap files can be safely erased on reboot (it's even tempting to think that that would be safer, though I don't think it really is).  But consider a system consistently short on physical memory: during boot, swapspace will see the swapfiles left by the previous session, and reinstate them immediately at very little cost, ready for use when they are needed.  If they had been erased during reboot, swapspace would have to allocate new ones on disk when it recognized the need for more virtual memory, which takes much more time and resources.