linux-kernel - Re: [RFC v2 10/16] luo: luo

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives
Hash Suite for Android: free password hash cracker in your pocket
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <CA+CK2bDx6DAKvW5jDajDkTzzsaR9fLWS6EFSDHCq893hOCW_7Q@mail.gmail.com>
Date: Sun, 8 Jun 2025 12:35:19 -0400
From: Pasha Tatashin <pasha.tatashin@...een.com>
To: Pratyush Yadav <pratyush@...nel.org>
Cc: jasonmiu@...gle.com, graf@...zon.com, changyuanl@...gle.com, 
	rppt@...nel.org, dmatlack@...gle.com, rientjes@...gle.com, corbet@....net, 
	rdunlap@...radead.org, ilpo.jarvinen@...ux.intel.com, kanie@...ux.alibaba.com, 
	ojeda@...nel.org, aliceryhl@...gle.com, masahiroy@...nel.org, 
	akpm@...ux-foundation.org, tj@...nel.org, yoann.congal@...le.fr, 
	mmaurer@...gle.com, roman.gushchin@...ux.dev, chenridong@...wei.com, 
	axboe@...nel.dk, mark.rutland@....com, jannh@...gle.com, 
	vincent.guittot@...aro.org, hannes@...xchg.org, dan.j.williams@...el.com, 
	david@...hat.com, joel.granados@...nel.org, rostedt@...dmis.org, 
	anna.schumaker@...cle.com, song@...nel.org, zhangguopeng@...inos.cn, 
	linux@...ssschuh.net, linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org, 
	linux-mm@...ck.org, gregkh@...uxfoundation.org, tglx@...utronix.de, 
	mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com, x86@...nel.org, 
	hpa@...or.com, rafael@...nel.org, dakr@...nel.org, 
	bartosz.golaszewski@...aro.org, cw00.choi@...sung.com, 
	myungjoo.ham@...sung.com, yesanishhere@...il.com, Jonathan.Cameron@...wei.com, 
	quic_zijuhu@...cinc.com, aleksander.lobakin@...el.com, ira.weiny@...el.com, 
	andriy.shevchenko@...ux.intel.com, leon@...nel.org, lukas@...ner.de, 
	bhelgaas@...gle.com, wagi@...nel.org, djeffery@...hat.com, 
	stuart.w.hayes@...il.com
Subject: Re: [RFC v2 10/16] luo: luo_ioctl: add ioctl interface

On Thu, Jun 5, 2025 at 12:16 PM Pratyush Yadav <pratyush@...nel.org> wrote:
>
> On Thu, May 15 2025, Pasha Tatashin wrote:
>
> > Introduce the user-space interface for the Live Update Orchestrator
> > via ioctl commands, enabling external control over the live update
> > process and management of preserved resources.
> >
> > Create a misc character device at /dev/liveupdate. Access
> > to this device requires the CAP_SYS_ADMIN capability.
> >
> > A new UAPI header, <uapi/linux/liveupdate.h>, defines the necessary
> > structures. The magic number is registered in
> > Documentation/userspace-api/ioctl/ioctl-number.rst.
> >
> > Signed-off-by: Pasha Tatashin <pasha.tatashin@...een.com>
> > ---
> [...]
> > +static int luo_ioctl_fd_preserve(struct liveupdate_fd *luo_fd)
> > +{
> > +     struct file *file;
> > +     int ret;
> > +
> > +     file = fget(luo_fd->fd);
> > +     if (!file) {
> > +             pr_err("Bad file descriptor\n");
> > +             return -EBADF;
> > +     }
> > +
> > +     ret = luo_register_file(&luo_fd->token, file);
> > +     if (ret)
> > +             fput(file);
> > +
> > +     return ret;
> > +}
> > +
> > +static int luo_ioctl_fd_unpreserve(u64 token)
> > +{
>
> This leaks the refcount on the file that preserve took. Perhaps
> luo_unregister_file() should return the file it unregistered, so this
> can do fput(file)?

Thank you, David Matlack also noticed this leak, I fixed it.

>
> > +     return luo_unregister_file(token);
> > +}
> > +
> > +static int luo_ioctl_fd_restore(struct liveupdate_fd *luo_fd)
> > +{
> > +     struct file *file;
> > +     int ret;
> > +     int fd;
> > +
> > +     fd = get_unused_fd_flags(O_CLOEXEC);
> > +     if (fd < 0) {
> > +             pr_err("Failed to allocate new fd: %d\n", fd);
> > +             return fd;
> > +     }
> > +
> > +     ret = luo_retrieve_file(luo_fd->token, &file);
> > +     if (ret < 0) {
> > +             put_unused_fd(fd);
> > +
> > +             return ret;
> > +     }
> > +
> > +     fd_install(fd, file);
> > +     luo_fd->fd = fd;
> > +
> > +     return 0;
> > +}
> > +
> > +static int luo_open(struct inode *inodep, struct file *filep)
> > +{
> > +     if (!capable(CAP_SYS_ADMIN))
> > +             return -EACCES;
> > +
> > +     if (filep->f_flags & O_EXCL)
> > +             return -EINVAL;
> > +
> > +     return 0;
> > +}
> > +
> > +static long luo_ioctl(struct file *filep, unsigned int cmd, unsigned long arg)
> > +{
> > +     void __user *argp = (void __user *)arg;
> > +     struct liveupdate_fd luo_fd;
> > +     enum liveupdate_state state;
> > +     int ret = 0;
> > +     u64 token;
> > +
> > +     if (_IOC_TYPE(cmd) != LIVEUPDATE_IOCTL_TYPE)
> > +             return -ENOTTY;
> > +
> > +     switch (cmd) {
> > +     case LIVEUPDATE_IOCTL_GET_STATE:
> > +             state = READ_ONCE(luo_state);
> > +             if (copy_to_user(argp, &state, sizeof(luo_state)))
> > +                     ret = -EFAULT;
> > +             break;
> > +
> > +     case LIVEUPDATE_IOCTL_EVENT_PREPARE:
> > +             ret = luo_prepare();
> > +             break;
> > +
> > +     case LIVEUPDATE_IOCTL_EVENT_FREEZE:
> > +             ret = luo_freeze();
> > +             break;
> > +
> > +     case LIVEUPDATE_IOCTL_EVENT_FINISH:
> > +             ret = luo_finish();
> > +             break;
> > +
> > +     case LIVEUPDATE_IOCTL_EVENT_CANCEL:
> > +             ret = luo_cancel();
> > +             break;
> > +
> > +     case LIVEUPDATE_IOCTL_FD_PRESERVE:
> > +             if (copy_from_user(&luo_fd, argp, sizeof(luo_fd))) {
> > +                     ret = -EFAULT;
> > +                     break;
> > +             }
> > +
> > +             ret = luo_ioctl_fd_preserve(&luo_fd);
> > +             if (!ret && copy_to_user(argp, &luo_fd, sizeof(luo_fd)))
> > +                     ret = -EFAULT;
>
> luo_unregister_file() is needed here on error.
>

Done, thank you.

Pasha