On Sun, Apr 14, 2024 at 01:58:55PM -0700, Luis Chamberlain wrote:
> On Sun, Apr 14, 2024 at 10:05:05PM +0300, Alexey Dobriyan wrote:
> > --- a/include/linux/fs.h
> > +++ b/include/linux/fs.h
> > @@ -3616,4 +3616,12 @@ extern int vfs_fadvise(struct file *file, loff_t
> > offset, loff_t len,
> > extern int generic_fadvise(struct file *file, loff_t offset, loff_t len,
> > int advice);
> >
> > +/*
> > + * Use this if data from userspace end up as directory/filename on
> > + * some virtual filesystem.
> > + */
> > +static inline bool string_is_vfs_ready(const char *s)
> > +{
> > + return strcmp(s, ".") != 0 && strcmp(s, "..") != 0 && !strchr(s, '/');
> > +}
> > #endif /* _LINUX_FS_H */
> > --- a/kernel/module/main.c
> > +++ b/kernel/module/main.c
> > @@ -2893,6 +2893,11 @@ static int load_module(struct load_info *info, const
> > char __user *uargs,
> >
> > audit_log_kern_module(mod->name);
> >
> > + if (!string_is_vfs_ready(mod->name)) {
> > + err = -EINVAL;
> > + goto free_module;
> > + }
> > +
>
> Sensible change however to put string_is_vfs_ready() in include/linux/fs.h
> is a stretch if there really are no other users.
This is forward thinking patch :-)
Other subsystems may create files/directories in proc/sysfs, and should
check for bad names as well:
/proc/2821/net/dev_snmp6/eth0
This looks exactly like something coming from userspace and making it
into /proc, so the filter function doesn't belong to kernel/module/internal.h
