Messages in this thread | | | Date | Sun, 6 Apr 2003 22:56:42 -0400 (EDT) | From | Mark Grosberg <> | Subject | Re: [PATCH] new syscall: flink |
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On Sun, Apr 6 2003, H. Peter Anvin wrote:
> > Suppose I give you an O_RDONLY handle to a file which you then > > flink and gain write access too ? > > This, I believe, is the real issue. However, we already have that > problem:
As far as I understand it, isn't the protection information stored in the inode? The flink call is just linking an inode into a directory that the caller has write access to. The permissions and ownership of the file shouldn't change.
> int main(int argc, char *argv[]) > { > int rfd, wfd; > char filebuf[PATH_MAX]; > > rfd = open("testfile", O_RDONLY|O_CREAT, 0666); > /* Now rfd is a read-only file descriptor */
There is nothing stopping the caller from re-opening the to-be flinked() file descriptor read-write using its name if the caller has permissions. So I don't see why that case is different.
Other than that, HPA's responses make sense.
Personally, I would like to see this system call in Linux. It does make certain thing easier. Not necessarily even in a security context, but sometimes its generally useful to be able to make a hard link to an already open file rather than track the name.
L8r, Mark G.
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