[PATCH net-next 1/2 v5] uevent: add alloc_uevent_skb() helper

Christian Brauner
2018-04-29T10:44:11Z

This patch adds alloc_uevent_skb() in preparation for follow up patches.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
---
v4->v5:
* patch unchanged
v3->v4:
* non-functional changes:
initialize some variables again explicitly to make it obvious to
readers that they are correctly set
v2->v3:
* new approach: patch added
v1->v2:
* different approach in different patchset
v0->v1:
* different approach in different patchset
---
lib/kobject_uevent.c | 47 ++++++++++++++++++++++++++++++++------------
1 file changed, 34 insertions(+), 13 deletions(-)

diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c
index 15ea216a67ce..649bf60a9440 100644
--- a/lib/kobject_uevent.c
+++ b/lib/kobject_uevent.c
@@ -22,6 +22,7 @@
#include <linux/socket.h>
#include <linux/skbuff.h>
#include <linux/netlink.h>
+#include <linux/uidgid.h>
#include <linux/uuid.h>
#include <linux/ctype.h>
#include <net/sock.h>
@@ -296,6 +297,38 @@ static void cleanup_uevent_env(struct subprocess_info *info)
}
#endif

+#ifdef CONFIG_NET
+static struct sk_buff *alloc_uevent_skb(struct kobj_uevent_env *env,
+ const char *action_string,
+ const char *devpath)
+{
+ struct netlink_skb_parms *parms;
+ struct sk_buff *skb = NULL;
+ char *scratch;
+ size_t len;
+
+ /* allocate message with maximum possible size */
+ len = strlen(action_string) + strlen(devpath) + 2;
+ skb = alloc_skb(len + env->buflen, GFP_KERNEL);
+ if (!skb)
+ return NULL;
+
+ /* add header */
+ scratch = skb_put(skb, len);
+ sprintf(scratch, "%s@%s", action_string, devpath);
+
+ skb_put_data(skb, env->buf, env->buflen);
+
+ parms = &NETLINK_CB(skb);
+ parms->creds.uid = GLOBAL_ROOT_UID;
+ parms->creds.gid = GLOBAL_ROOT_GID;
+ parms->dst_group = 1;
+ parms->portid = 0;
+
+ return skb;
+}
+#endif
+
static int kobject_uevent_net_broadcast(struct kobject *kobj,
struct kobj_uevent_env *env,
const char *action_string,
@@ -314,22 +347,10 @@ static int kobject_uevent_net_broadcast(struct kobject *kobj,
continue;

if (!skb) {
- /* allocate message with the maximum possible size */
- size_t len = strlen(action_string) + strlen(devpath) + 2;
- char *scratch;
-
retval = -ENOMEM;
- skb = alloc_skb(len + env->buflen, GFP_KERNEL);
+ skb = alloc_uevent_skb(env, action_string, devpath);
if (!skb)
continue;
-
- /* add header */
- scratch = skb_put(skb, len);
- sprintf(scratch, "%s@%s", action_string, devpath);
-
- skb_put_data(skb, env->buf, env->buflen);
-
- NETLINK_CB(skb).dst_group = 1;
}

retval = netlink_broadcast_filtered(uevent_sock, skb_get(skb),
--
2.17.0