--- /dev/null
+What: /sys/.../uevent
+Date: May 2017
+KernelVersion: 4.12
+Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org>
+Description:
+ Enable passing additional variables for synthetic uevents that
+ are generated by writing /sys/.../uevent file.
+
+ Recognized extended format is ACTION [UUID [KEY=VALUE ...].
+
+ The ACTION is compulsory - it is the name of the uevent action
+ ("add", "change", "remove"). There is no change compared to
+ previous functionality here. The rest of the extended format
+ is optional.
+
+ You need to pass UUID first before any KEY=VALUE pairs.
+ The UUID must be in "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"
+ format where 'x' is a hex digit. The UUID is considered to be
+ a transaction identifier so it's possible to use the same UUID
+ value for one or more synthetic uevents in which case we
+ logically group these uevents together for any userspace
+ listeners. The UUID value appears in uevent as
+ "SYNTH_UUID=xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx" environment
+ variable.
+
+ If UUID is not passed in, the generated synthetic uevent gains
+ "SYNTH_UUID=0" environment variable automatically.
+
+ The KEY=VALUE pairs can contain alphanumeric characters only.
+ It's possible to define zero or more pairs - each pair is then
+ delimited by a space character ' '. Each pair appears in
+ synthetic uevent as "SYNTH_ARG_KEY=VALUE". That means the KEY
+ name gains "SYNTH_ARG_" prefix to avoid possible collisions
+ with existing variables.
+
+ Example of valid sequence written to the uevent file:
+
+ add fe4d7c9d-b8c6-4a70-9ef1-3d8a58d18eed A=1 B=abc
+
+ This generates synthetic uevent including these variables:
+
+ ACTION=add
+ SYNTH_ARG_A=1
+ SYNTH_ARG_B=abc
+ SYNTH_UUID=fe4d7c9d-b8c6-4a70-9ef1-3d8a58d18eed
+Users:
+ udev, userspace tools generating synthetic uevents
static ssize_t uevent_store(struct device_driver *drv, const char *buf,
size_t count)
{
- enum kobject_action action;
-
- if (kobject_action_type(buf, count, &action) == 0)
- kobject_uevent(&drv->p->kobj, action);
+ kobject_synth_uevent(&drv->p->kobj, buf, count);
return count;
}
static DRIVER_ATTR_WO(uevent);
static ssize_t bus_uevent_store(struct bus_type *bus,
const char *buf, size_t count)
{
- enum kobject_action action;
-
- if (kobject_action_type(buf, count, &action) == 0)
- kobject_uevent(&bus->p->subsys.kobj, action);
+ kobject_synth_uevent(&bus->p->subsys.kobj, buf, count);
return count;
}
static BUS_ATTR(uevent, S_IWUSR, NULL, bus_uevent_store);
#include <linux/socket.h>
#include <linux/skbuff.h>
#include <linux/netlink.h>
+#include <linux/uuid.h>
+#include <linux/ctype.h>
#include <net/sock.h>
#include <net/net_namespace.h>
[KOBJ_OFFLINE] = "offline",
};
-/**
- * kobject_action_type - translate action string to numeric type
- *
- * @buf: buffer containing the action string, newline is ignored
- * @count: length of buffer
- * @type: pointer to the location to store the action type
- *
- * Returns 0 if the action string was recognized.
- */
-int kobject_action_type(const char *buf, size_t count,
- enum kobject_action *type)
+static int kobject_action_type(const char *buf, size_t count,
+ enum kobject_action *type,
+ const char **args)
{
enum kobject_action action;
+ size_t count_first;
+ const char *args_start;
int ret = -EINVAL;
if (count && (buf[count-1] == '\n' || buf[count-1] == '\0'))
if (!count)
goto out;
+ args_start = strnchr(buf, count, ' ');
+ if (args_start) {
+ count_first = args_start - buf;
+ args_start = args_start + 1;
+ } else
+ count_first = count;
+
for (action = 0; action < ARRAY_SIZE(kobject_actions); action++) {
- if (strncmp(kobject_actions[action], buf, count) != 0)
+ if (strncmp(kobject_actions[action], buf, count_first) != 0)
continue;
- if (kobject_actions[action][count] != '\0')
+ if (kobject_actions[action][count_first] != '\0')
continue;
+ if (args)
+ *args = args_start;
*type = action;
ret = 0;
break;
return ret;
}
+static const char *action_arg_word_end(const char *buf, const char *buf_end,
+ char delim)
+{
+ const char *next = buf;
+
+ while (next <= buf_end && *next != delim)
+ if (!isalnum(*next++))
+ return NULL;
+
+ if (next == buf)
+ return NULL;
+
+ return next;
+}
+
+static int kobject_action_args(const char *buf, size_t count,
+ struct kobj_uevent_env **ret_env)
+{
+ struct kobj_uevent_env *env = NULL;
+ const char *next, *buf_end, *key;
+ int key_len;
+ int r = -EINVAL;
+
+ if (count && (buf[count - 1] == '\n' || buf[count - 1] == '\0'))
+ count--;
+
+ if (!count)
+ return -EINVAL;
+
+ env = kzalloc(sizeof(*env), GFP_KERNEL);
+ if (!env)
+ return -ENOMEM;
+
+ /* first arg is UUID */
+ if (count < UUID_STRING_LEN || !uuid_is_valid(buf) ||
+ add_uevent_var(env, "SYNTH_UUID=%.*s", UUID_STRING_LEN, buf))
+ goto out;
+
+ /*
+ * the rest are custom environment variables in KEY=VALUE
+ * format with ' ' delimiter between each KEY=VALUE pair
+ */
+ next = buf + UUID_STRING_LEN;
+ buf_end = buf + count - 1;
+
+ while (next <= buf_end) {
+ if (*next != ' ')
+ goto out;
+
+ /* skip the ' ', key must follow */
+ key = ++next;
+ if (key > buf_end)
+ goto out;
+
+ buf = next;
+ next = action_arg_word_end(buf, buf_end, '=');
+ if (!next || next > buf_end || *next != '=')
+ goto out;
+ key_len = next - buf;
+
+ /* skip the '=', value must follow */
+ if (++next > buf_end)
+ goto out;
+
+ buf = next;
+ next = action_arg_word_end(buf, buf_end, ' ');
+ if (!next)
+ goto out;
+
+ if (add_uevent_var(env, "SYNTH_ARG_%.*s=%.*s",
+ key_len, key, (int) (next - buf), buf))
+ goto out;
+ }
+
+ r = 0;
+out:
+ if (r)
+ kfree(env);
+ else
+ *ret_env = env;
+ return r;
+}
+
+/**
+ * kobject_synth_uevent - send synthetic uevent with arguments
+ *
+ * @kobj: struct kobject for which synthetic uevent is to be generated
+ * @buf: buffer containing action type and action args, newline is ignored
+ * @count: length of buffer
+ *
+ * Returns 0 if kobject_synthetic_uevent() is completed with success or the
+ * corresponding error when it fails.
+ */
+int kobject_synth_uevent(struct kobject *kobj, const char *buf, size_t count)
+{
+ char *no_uuid_envp[] = { "SYNTH_UUID=0", NULL };
+ enum kobject_action action;
+ const char *action_args;
+ struct kobj_uevent_env *env;
+ const char *msg = NULL, *devpath;
+ int r;
+
+ r = kobject_action_type(buf, count, &action, &action_args);
+ if (r) {
+ msg = "unknown uevent action string\n";
+ goto out;
+ }
+
+ if (!action_args) {
+ r = kobject_uevent_env(kobj, action, no_uuid_envp);
+ goto out;
+ }
+
+ r = kobject_action_args(action_args,
+ count - (action_args - buf), &env);
+ if (r == -EINVAL) {
+ msg = "incorrect uevent action arguments\n";
+ goto out;
+ }
+
+ if (r)
+ goto out;
+
+ r = kobject_uevent_env(kobj, action, env->envp);
+ kfree(env);
+out:
+ if (r) {
+ devpath = kobject_get_path(kobj, GFP_KERNEL);
+ printk(KERN_WARNING "synth uevent: %s: %s",
+ devpath ?: "unknown device",
+ msg ?: "failed to send uevent");
+ kfree(devpath);
+ }
+ return r;
+}
+
#ifdef CONFIG_NET
static int kobj_bcast_filter(struct sock *dsk, struct sk_buff *skb, void *data)
{
projects / GitHub / moto-9609 / android_kernel_motorola_exynos9610.git / commitdiff