Pekka J Enberg <penberg@xxxxxxxxxxxxxx> writes in
gmane.linux.file-systems,gmane.linux.kernel:
> From: Pekka Enberg <penberg@xxxxxxxxxxxxxx>
>
> 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@xxxxxxxxxxxxxx>
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.
/ Kari Hurtta
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