On Sun, Feb 11, 2018 at 09:50:28PM +0000, Enrico Weigelt, metux IT consult wrote: > From: "Enrico Weigelt, metux IT consult" <i...@metux.net> > > This driver implements the Plan9 capability devices, used for > switching user id via capability tokens. > > https://9p.io/sys/doc/auth.html > --- > drivers/staging/Kconfig | 2 + > drivers/staging/Makefile | 1 + > drivers/staging/p9caps/Kconfig | 11 ++ > drivers/staging/p9caps/Makefile | 1 + > drivers/staging/p9caps/p9caps.c | 369 > ++++++++++++++++++++++++++++++++++++++++ > 5 files changed, 384 insertions(+) > create mode 100644 drivers/staging/p9caps/Kconfig > create mode 100644 drivers/staging/p9caps/Makefile > create mode 100644 drivers/staging/p9caps/p9caps.c > > diff --git a/drivers/staging/Kconfig b/drivers/staging/Kconfig > index 554683912cff..23f325339fe8 100644 > --- a/drivers/staging/Kconfig > +++ b/drivers/staging/Kconfig > @@ -118,4 +118,6 @@ source "drivers/staging/vboxvideo/Kconfig" > > source "drivers/staging/pi433/Kconfig" > > +source "drivers/staging/p9caps/Kconfig" > + > endif # STAGING > diff --git a/drivers/staging/Makefile b/drivers/staging/Makefile > index 6e536020029a..eccdf4643453 100644 > --- a/drivers/staging/Makefile > +++ b/drivers/staging/Makefile > @@ -3,6 +3,7 @@ > > obj-y += media/ > obj-y += typec/ > +obj-$(CONFIG_PLAN9CAPS) += p9caps/ > obj-$(CONFIG_IRDA) += irda/net/ > obj-$(CONFIG_IRDA) += irda/drivers/ > obj-$(CONFIG_PRISM2_USB) += wlan-ng/ > diff --git a/drivers/staging/p9caps/Kconfig b/drivers/staging/p9caps/Kconfig > new file mode 100644 > index 000000000000..b909daaa79ce > --- /dev/null > +++ b/drivers/staging/p9caps/Kconfig > @@ -0,0 +1,11 @@ > +config PLAN9CAPS > + tristate "Plan 9 capability device" > + default n > + select CRYPTO_HMAC > + select CRYPTO_SHA1 > + help > + This module implements the Plan 9 capability devices > + /dev/caphash and /dev/capuse > + > + To compile this driver as a module, choose > + M here: the module will be called p9caps. > diff --git a/drivers/staging/p9caps/Makefile b/drivers/staging/p9caps/Makefile > new file mode 100644 > index 000000000000..67d38099a249 > --- /dev/null > +++ b/drivers/staging/p9caps/Makefile > @@ -0,0 +1 @@ > +obj-$(CONFIG_PLAN9CAPS) += p9caps.o > diff --git a/drivers/staging/p9caps/p9caps.c b/drivers/staging/p9caps/p9caps.c > new file mode 100644 > index 000000000000..e46b09821c18 > --- /dev/null > +++ b/drivers/staging/p9caps/p9caps.c > @@ -0,0 +1,369 @@ > + > +#include <linux/kernel.h> > +#include <linux/module.h> > +#include <linux/slab.h> > +#include <linux/fs.h> > +#include <linux/errno.h> > +#include <linux/fcntl.h> > +#include <linux/cdev.h> > +#include <linux/list.h> > +#include <linux/mm.h> > +#include <linux/string.h> > +#include <linux/scatterlist.h> > +#include <linux/cred.h> > +#include <linux/err.h> > +#include <linux/user_namespace.h> > +#include <linux/mutex.h> > +#include <crypto/hash.h> > +#include <crypto/sha.h> > + > +/* > + * Plan9 /dev/caphash and /dev/capuse device > + * > + * 2DO: - caphash should only allow one process (per userns) > + * - support textual user names > + * - invalidate old caps > + */ > + > +#define DEVICE_CAPUSE "/dev/capuse" > +#define DEVICE_CAPHASH "/dev/caphash" > + > +struct caphash_entry { > + struct list_head list; > + struct user_namespace *user_ns; > + char data[SHA1_DIGEST_SIZE]; > +}; > + > +struct caphash_writer { > + struct list_head list; > + struct user_namespace *user_ns; > +}; > + > +static dev_t caphash_devid = 0; > +static dev_t capuse_devid = 0; > + > +static LIST_HEAD(caphash_entries); > +static LIST_HEAD(caphash_writers); > + > +static DEFINE_MUTEX(lock); > + > +struct crypto_ahash *hmac_tfm = NULL; > + > +static int caphash_open(struct inode *inode, struct file *filp) > +{ > + struct caphash_writer *tmp = NULL; > + struct user_namespace *user_ns = current_user_ns(); > + int retval = 0; > + struct list_head *pos, *q; > + > + /* make sure only one instance per namespace can be opened */
... at a time might be better to keep this state in the user_ns itself, would avoid kzalloc below. Would it be worth doing any privilege checking here? (incidentally, for historical reference, https://lkml.org/lkml/2010/4/20/404 :) > + mutex_lock(&lock); > + > + list_for_each_safe(pos, q, &(caphash_writers)) { > + tmp = list_entry(pos, struct caphash_writer, list); > + if (tmp->user_ns == user_ns) { > + pr_err("already locked in this namespace\n"); > + retval = -EBUSY; > + goto out; > + } > + } > + > + if (!(tmp = kzalloc(sizeof(struct caphash_writer), GFP_KERNEL))) { > + retval = -ENOMEM; > + goto out; > + } > + > + tmp->user_ns = get_user_ns(user_ns); > + list_add(&(tmp->list), &caphash_writers); > + > +out: > + mutex_unlock(&lock); > + return retval; > +}
