Re: path_post_lookup

From: Chris Wright (chriswat_private)
Date: Wed Sep 03 2003 - 15:34:05 PDT

  • Next message: Charles Levert: "Re: path_post_lookup"

    * Charles Levert (chuckat_private) wrote:
    > On Wed, Sep 03, 2003 at 02:23:45PM -0700, Chris Wright wrote:
    > > This sounds like multiple mountpoints and bind mounts (both of which can
    > > be specific to the processes namespace) will be problematic for you.
    > 
    > Yes.  This is what Stephen said too.
    > 
    > I have a Linux kernel question then.  Assume that a filesystem is
    > mounted both over /a and /b.  Then /a/x and /b/x are the same file.
    > In the dcache, do they both get the same dentry, or does each one get
    > its own dentry?  If it's the former, then I have a problem.  If it's the
    > latter, then I'm fine if I start to walk the tree for a specific dentry.
    
    They get the same dentry.
    
    > > > > On a similar note, since Trond's intents patch the permission hook now
    > > > > has nameidata available.  I'd like to update the API to use nameidata
    > > > > where apropos.  Would this help?
    > > > 
    > > > Is that file_permission or inode_permission?  What would be its prototype?
    > > 
    > > int inode_permission(struct nameidata *nd, int mask);
    > 
    > I think that would be great.
    > 
    > How will you be able to pull this off?  security_inode_permission appears
    > both in permission and exec_permission_lite.  The nameidata is not
    > available in exec_permission_lite.
    
    Yes, you're right.  It's easily available from the call site, however.
    
    > Is permission called from open(), or is it called only from read()
    > or write()?  I would rather have open() return an error.
    
    open()
    
    thanks,
    -chris
    -- 
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