Messages in this thread | | | Date | Tue, 20 Apr 2010 20:04:06 -0700 | From | Greg KH <> | Subject | Re: [PATCH 3/3] p9auth: add p9auth driver |
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On Tue, Apr 20, 2010 at 08:29:08PM -0500, Serge E. Hallyn wrote: > This is a driver that adds Plan 9 style capability device > implementation. See Documentation/p9auth.txt for a description > of how to use this.
Hm, you didn't originally write this driver, so it would be good to get some original authorship information in here to keep everything correct, right?
> Documentation/p9auth.txt | 47 ++++ > drivers/char/Kconfig | 2 + > drivers/char/Makefile | 2 + > drivers/char/p9auth/Kconfig | 9 + > drivers/char/p9auth/Makefile | 1 + > drivers/char/p9auth/p9auth.c | 517 ++++++++++++++++++++++++++++++++++++++++++
Is this code really ready for drivers/char/? What has changed in it that makes it ok to move out of the staging tree?
And who is going to maintain it? You? Or someone else?
> 6 files changed, 578 insertions(+), 0 deletions(-) > create mode 100644 Documentation/p9auth.txt > create mode 100644 drivers/char/p9auth/Kconfig > create mode 100644 drivers/char/p9auth/Makefile > create mode 100644 drivers/char/p9auth/p9auth.c > > diff --git a/Documentation/p9auth.txt b/Documentation/p9auth.txt > new file mode 100644 > index 0000000..14a69d8 > --- /dev/null > +++ b/Documentation/p9auth.txt > @@ -0,0 +1,47 @@ > +The p9auth device driver implements a plan-9 factotum-like > +capability API. Tasks which are privileged (authorized by > +possession of the CAP_GRANT_ID privilege (POSIX capability)) > +can write new capabilities to /dev/caphash. The kernel then > +stores these until a task uses them by writing to the > +/dev/capuse device. Each capability represents the ability > +for a task running as userid X to switch to userid Y and > +some set of groups. Each capability may be used only once, > +and unused capabilities are cleared after two minutes. > + > +The following examples shows how to use the API. Shell 1 > +contains a privileged root shell. Shell 2 contains an > +unprivileged shell as user 501 in the same user namespace. If > +not already done, the privileged shell should create the p9auth > +devices: > + > + majfile=/sys/module/p9auth/parameters/cap_major > + minfile=/sys/module/p9auth/parameters/cap_minor > + maj=`cat $majfile` > + mknod /dev/caphash c $maj 0 > + min=`cat $minfile` > + mknod /dev/capuse c $maj 1 > + chmod ugo+w /dev/capuse
That is incorrect, you don't need the cap_major/minor files at all, the device node should be automatically created for you, right?
And do you really want to do all of this control through a device node? Why?
> +DEFINE_MUTEX(cap_mutex); /* TODO fix up the locking one day */
One might hope that today would be that day...
Also, please run this through sparse. This is a variable that doesn't need to be global.
> +struct cap_dev { > + struct cdev cdev; > +};
Do you really need to do it this way? A cdev for a single device node? That's major overkill.
> +static int cap_major = CAP_MAJOR; > +static int cap_minor;
Just always use a dynamic misc device, you never need a whole major for this.
> +module_param(cap_major, int, S_IRUGO); > +module_param(cap_minor, int, S_IRUGO);
Can be removed.
> +MODULE_AUTHOR("Ashwin Ganti");
Hm, who is going to maintain this, you, or Ashwin?
> +static void hexdump(unsigned char *buf, unsigned int len) > +{ > + while (len--) > + printk(KERN_DEBUG "%02x", *buf++); > + printk(KERN_DEBUG "\n"); > +}
We have a built-in function for this already.
Oh, this function is also incorrect, which is a good reason to use the built-in ones.
I'm going to stop now, this doesn't belong in drivers/char/ yet, it needs work...
thanks,
greg k-h
> +/* > + * read an entry. For now it is > + * source_user@target_user@rand > + * Next it will become > + * source_user@target_user@target_group@numgroups@grp1..@grpn@rand > + */
Hm, wait, one more.... The kernel/user api is going to change some time in the future? Please fix this now before it gets merged.
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