Messages in this thread |  | | Date | Fri, 17 Jan 2014 18:18:47 +0000 | From | One Thousand Gnomes <> | Subject | Re: [PATCH v7 1/7] VFS: Introduce new O_DENY* open flags |
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> +#define ESHAREDENIED 258 /* File is locked with a sharelock */
Have you prepared C library patches to match this ?
(and why not just use EPERM, it has the meaning you want already)
> + * Check to see if there's a share_reservation conflict. LOCK_READ/LOCK_WRITE > + * tell us whether the reservation allows other readers and writers. > + */ > +static int > +locks_mand_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl) > +{
Shouldn't this also check for CAP_SYS_DAC or some similar permission so that root can override such a mess (eg to fix full disks in an emergency) ?
> + > + /* > + * For sharelock mounts if a file was created but not opened, we need > + * to keep parent i_mutex until we finish the open to prevent races when > + * somebody opens newly created by us file and locks it with a sharelock > + * before we open it. > + */ > + if (IS_SHARELOCK(dir->d_inode) && error > 0 && *opened & FILE_CREATED) { > + /* Don't check for write permission, don't truncate */ > + open_flag &= ~O_TRUNC; > + will_truncate = false; > + acc_mode = MAY_OPEN; > + path_to_nameidata(path, nd); > + > + error = may_open(&nd->path, acc_mode, open_flag); > + if (error) { > + mutex_unlock(&dir->d_inode->i_mutex); > + goto out; > + } > + file->f_path.mnt = nd->path.mnt; > + error = finish_open(file, nd->path.dentry, NULL, opened); > + if (error) { > + mutex_unlock(&dir->d_inode->i_mutex); > + if (error == -EOPENSTALE) > + goto stale_open; > + goto out; > + } > + error = sharelock_lock_file(file); > + mutex_unlock(&dir->d_inode->i_mutex); > + if (error) > + goto exit_fput; > + goto opened; > + } > + > mutex_unlock(&dir->d_inode->i_mutex);
What stops the file system changing mount flags via a remount between these two ?
> > if (error <= 0) { > @@ -3034,6 +3073,18 @@ finish_open_created: > goto stale_open; > goto out; > } > + > + if (IS_SHARELOCK(dir->d_inode)) { > + /* > + * Lock parent i_mutex to prevent races with sharelocks on > + * newly created files. > + */ > + mutex_lock(&dir->d_inode->i_mutex); > + error = sharelock_lock_file(file); > + mutex_unlock(&dir->d_inode->i_mutex); > + if (error) > + goto exit_fput; > + } > opened:
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