Messages in this thread | | | Date | Thu, 20 Jul 2006 23:09:01 +0200 | From | Björn Steinbrink <> | Subject | Re: [RFC/PATCH] revoke/frevoke system calls |
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On 2006.07.20 23:02:53 +0300, Kari Hurtta wrote: > Pekka J Enberg <penberg@cs.Helsinki.FI> writes in > gmane.linux.file-systems,gmane.linux.kernel: > > > From: Pekka Enberg <penberg@cs.helsinki.fi> > > > > This patch implements the revoke(2) and frevoke(2) system calls for all > > types of files. We revoke files in two passes: first we scan all open > > files that refer to the inode and substitute the struct file pointer in fd > > table with NULL causing all subsequent operations on that fd to fail. > > After we have done that to all file descriptors, we close the files and > > take down mmaps. > > > > Note that now we need to unconditionally do fput/fget in sys_write and > > sys_read because they race with do_revoke. > > > > Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi> > > What permissions is needed revoke access of other users open > files ? > > > +asmlinkage int sys_revoke(const char __user *filename) > > +{ > > + int err; > > + struct nameidata nd; > > + > > + err = __user_walk(filename, 0, &nd); > > + if (!err) { > > + err = do_revoke(nd.dentry->d_inode, NULL); > > + path_release(&nd); > > + } > > + return err; > > +} > > + > > +asmlinkage int sys_frevoke(unsigned int fd) > > +{ > > + struct file *file = fget(fd); > > + int err = -EBADF; > > + > > + if (file) { > > + err = do_revoke(file->f_dentry->d_inode, file); > > + fput(file); > > + } > > + return err; > > +} > > Is that requiring only that user is able to refer file ? > > > BSD manual page for revoke(2) seems say: > > Access to a file may be revoked only by its owner or the super user.
In do_revoke() there is:
+ if (current->fsuid != inode->i_uid && !capable(CAP_FOWNER)) { + ret = -EPERM; + goto out;
That pretty much matches what the BSD manpage says.
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