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Message-ID: <5703F356.6050107@bfs.de>
Date: Tue, 05 Apr 2016 19:18:14 +0200
From: walter harms <wharms@....de>
To: Guillaume Nault <g.nault@...halink.fr>
CC: netdev@...r.kernel.org, linux-ppp@...r.kernel.org,
Paul Mackerras <paulus@...ba.org>,
David Miller <davem@...emloft.net>
Subject: Re: [RFC PATCH 6/6] ppp: add rtnetlink device creation support
Am 05.04.2016 02:56, schrieb Guillaume Nault:
> Define PPP device handlers for use with rtnetlink.
> The only PPP specific attribute is IFLA_PPP_DEV_FD. It is mandatory and
> contains the file descriptor of the associated /dev/ppp instance (the
> file descriptor which would have been used for ioctl(PPPIOCNEWUNIT) in
> the ioctl-based API). The PPP device is removed when this file
> descriptor is released (same behaviour as with ioctl based PPP
> devices).
>
> PPP devices created with the rtnetlink API behave like the ones created
> with ioctl(PPPIOCNEWUNIT). In particular existing ioctls work the same
> way, no matter how the PPP device was created.
>
> However, there are a few differences between rtnl and ioctl based PPP
> devices. Rtnl based PPP devices can be removed with RTM_DELLINK
> messages (e.g. with "ip link del"), while the ones created with
> ioctl(PPPIOCNEWUNIT) can't.
> The interface name is also built differently: the number following the
> "ppp" prefix corresponds to the PPP unit number for ioctl based
> devices, while it is just an unrelated incrementing index for rtnl
> ones.
>
> Signed-off-by: Guillaume Nault <g.nault@...halink.fr>
> ---
> drivers/net/ppp/ppp_generic.c | 143 +++++++++++++++++++++++++++++++++++++-----
> include/uapi/linux/if_link.h | 8 +++
> 2 files changed, 136 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c
> index 516f8dc..ae40368 100644
> --- a/drivers/net/ppp/ppp_generic.c
> +++ b/drivers/net/ppp/ppp_generic.c
> @@ -46,6 +46,7 @@
> #include <linux/device.h>
> #include <linux/mutex.h>
> #include <linux/slab.h>
> +#include <linux/file.h>
> #include <asm/unaligned.h>
> #include <net/slhc_vj.h>
> #include <linux/atomic.h>
> @@ -185,7 +186,9 @@ struct channel {
>
> struct ppp_config {
> struct file *file;
> + s32 fd;
> s32 unit;
> + bool ifname_is_set;
> };
>
> /*
> @@ -286,6 +289,7 @@ static int unit_get(struct idr *p, void *ptr);
> static int unit_set(struct idr *p, void *ptr, int n);
> static void unit_put(struct idr *p, int n);
> static void *unit_find(struct idr *p, int n);
> +static void ppp_setup(struct net_device *dev);
>
> static const struct net_device_ops ppp_netdev_ops;
>
> @@ -989,7 +993,7 @@ static struct pernet_operations ppp_net_ops = {
> .size = sizeof(struct ppp_net),
> };
>
> -static int ppp_unit_register(struct ppp *ppp, int unit)
> +static int ppp_unit_register(struct ppp *ppp, int unit, bool ifname_is_set)
> {
> struct ppp_net *pn = ppp_pernet(ppp->ppp_net);
> int ret;
> @@ -1019,7 +1023,8 @@ static int ppp_unit_register(struct ppp *ppp, int unit)
> }
> ppp->file.index = ret;
>
> - snprintf(ppp->dev->name, IFNAMSIZ, "ppp%i", ppp->file.index);
> + if (!ifname_is_set)
> + snprintf(ppp->dev->name, IFNAMSIZ, "ppp%i", ppp->file.index);
>
> ret = register_netdevice(ppp->dev);
> if (ret < 0)
> @@ -1043,12 +1048,39 @@ static int ppp_dev_configure(struct net *src_net, struct net_device *dev,
> const struct ppp_config *conf)
> {
> struct ppp *ppp = netdev_priv(dev);
> + struct file *file;
> int indx;
> + int err;
> +
> + if (conf->fd < 0) {
> + file = conf->file;
> + if (!file) {
> + err = -EBADF;
> + goto out;
why not just return -EBADF;
> + }
> + } else {
> + file = fget(conf->fd);
> + if (!file) {
> + err = -EBADF;
> + goto out;
why not just return -EBADF;
> + }
just my 2 cents,
re,
wh
> +
> + if (file->f_op != &ppp_device_fops) {
> + err = -EBADF;
> + goto out;
> + }
> + }
> +
> + mutex_lock(&ppp_mutex);
> + if (file->private_data) {
> + err = -ENOTTY;
> + goto out_mutex;
> + }
>
> ppp->dev = dev;
> ppp->mru = PPP_MRU;
> ppp->ppp_net = src_net;
> - ppp->owner = conf->file;
> + ppp->owner = file;
>
> init_ppp_file(&ppp->file, INTERFACE);
> ppp->file.hdrlen = PPP_HDRLEN - 2; /* don't count proto bytes */
> @@ -1067,9 +1099,88 @@ static int ppp_dev_configure(struct net *src_net, struct net_device *dev,
> ppp->active_filter = NULL;
> #endif /* CONFIG_PPP_FILTER */
>
> - return ppp_unit_register(ppp, conf->unit);
> + err = ppp_unit_register(ppp, conf->unit, conf->ifname_is_set);
> + if (err < 0)
> + goto out_mutex;
> +
> + file->private_data = &ppp->file;
> +
> +out_mutex:
> + mutex_unlock(&ppp_mutex);
> +out:
> + if (conf->fd >= 0 && file)
> + fput(file);
> +
> + return err;
> }
>
> +static const struct nla_policy ppp_nl_policy[IFLA_PPP_MAX + 1] = {
> + [IFLA_PPP_DEV_FD] = { .type = NLA_S32 },
> +};
> +
> +static int ppp_nl_validate(struct nlattr *tb[], struct nlattr *data[])
> +{
> + if (!data)
> + return -EINVAL;
> +
> + if (!data[IFLA_PPP_DEV_FD])
> + return -EINVAL;
> + if (nla_get_s32(data[IFLA_PPP_DEV_FD]) < 0)
> + return -EBADF;
> +
> + return 0;
> +}
> +
> +static int ppp_nl_newlink(struct net *src_net, struct net_device *dev,
> + struct nlattr *tb[], struct nlattr *data[])
> +{
> + struct ppp_config conf = {
> + .file = NULL,
> + .unit = -1,
> + .ifname_is_set = true,
> + };
> +
> + conf.fd = nla_get_s32(data[IFLA_PPP_DEV_FD]);
> +
> + return ppp_dev_configure(src_net, dev, &conf);
> +}
> +
> +static void ppp_nl_dellink(struct net_device *dev, struct list_head *head)
> +{
> + unregister_netdevice_queue(dev, head);
> +}
> +
> +static size_t ppp_nl_get_size(const struct net_device *dev)
> +{
> + return 0;
> +}
> +
> +static int ppp_nl_fill_info(struct sk_buff *skb, const struct net_device *dev)
> +{
> + return 0;
> +}
> +
> +static struct net *ppp_nl_get_link_net(const struct net_device *dev)
> +{
> + struct ppp *ppp = netdev_priv(dev);
> +
> + return ppp->ppp_net;
> +}
> +
> +static struct rtnl_link_ops ppp_link_ops __read_mostly = {
> + .kind = "ppp",
> + .maxtype = IFLA_PPP_MAX,
> + .policy = ppp_nl_policy,
> + .priv_size = sizeof(struct ppp),
> + .setup = ppp_setup,
> + .validate = ppp_nl_validate,
> + .newlink = ppp_nl_newlink,
> + .dellink = ppp_nl_dellink,
> + .get_size = ppp_nl_get_size,
> + .fill_info = ppp_nl_fill_info,
> + .get_link_net = ppp_nl_get_link_net,
> +};
> +
> #define PPP_MAJOR 108
>
> /* Called at boot time if ppp is compiled into the kernel,
> @@ -1098,11 +1209,19 @@ static int __init ppp_init(void)
> goto out_chrdev;
> }
>
> + err = rtnl_link_register(&ppp_link_ops);
> + if (err) {
> + pr_err("failed to register rtnetlink PPP handler\n");
> + goto out_class;
> + }
> +
> /* not a big deal if we fail here :-) */
> device_create(ppp_class, NULL, MKDEV(PPP_MAJOR, 0), NULL, "ppp");
>
> return 0;
>
> +out_class:
> + class_destroy(ppp_class);
> out_chrdev:
> unregister_chrdev(PPP_MAJOR, "ppp");
> out_net:
> @@ -2846,7 +2965,9 @@ static int ppp_create_interface(struct net *net, struct file *file, int *unit)
> {
> struct ppp_config conf = {
> .file = file,
> + .fd = -1,
> .unit = *unit,
> + .ifname_is_set = false,
> };
> struct net_device *dev;
> struct ppp *ppp;
> @@ -2861,27 +2982,17 @@ static int ppp_create_interface(struct net *net, struct file *file, int *unit)
> dev_net_set(dev, net);
>
> rtnl_lock();
> - mutex_lock(&ppp_mutex);
> - if (file->private_data) {
> - err = -ENOTTY;
> - goto err_dev;
> - }
> -
> err = ppp_dev_configure(net, dev, &conf);
> if (err < 0)
> goto err_dev;
> + rtnl_unlock();
>
> ppp = netdev_priv(dev);
> *unit = ppp->file.index;
> - file->private_data = &ppp->file;
> -
> - mutex_unlock(&ppp_mutex);
> - rtnl_unlock();
>
> return 0;
>
> err_dev:
> - mutex_unlock(&ppp_mutex);
> rtnl_unlock();
> free_netdev(dev);
> err:
> @@ -3074,6 +3185,7 @@ static void __exit ppp_cleanup(void)
> /* should never happen */
> if (atomic_read(&ppp_unit_count) || atomic_read(&channel_count))
> pr_err("PPP: removing module but units remain!\n");
> + rtnl_link_unregister(&ppp_link_ops);
> unregister_chrdev(PPP_MAJOR, "ppp");
> device_destroy(ppp_class, MKDEV(PPP_MAJOR, 0));
> class_destroy(ppp_class);
> @@ -3132,4 +3244,5 @@ EXPORT_SYMBOL(ppp_register_compressor);
> EXPORT_SYMBOL(ppp_unregister_compressor);
> MODULE_LICENSE("GPL");
> MODULE_ALIAS_CHARDEV(PPP_MAJOR, 0);
> +MODULE_ALIAS_RTNL_LINK("ppp");
> MODULE_ALIAS("devname:ppp");
> diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h
> index c488066..f238de9 100644
> --- a/include/uapi/linux/if_link.h
> +++ b/include/uapi/linux/if_link.h
> @@ -515,6 +515,14 @@ enum {
> };
> #define IFLA_GENEVE_MAX (__IFLA_GENEVE_MAX - 1)
>
> +/* PPP section */
> +enum {
> + IFLA_PPP_UNSPEC,
> + IFLA_PPP_DEV_FD,
> + __IFLA_PPP_MAX,
> +};
> +#define IFLA_PPP_MAX (__IFLA_PPP_MAX - 1)
> +
> /* Bonding section */
>
> enum {
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