diff options
Diffstat (limited to 'Documentation/connector')
| -rw-r--r-- | Documentation/connector/.gitignore | 1 | ||||
| -rw-r--r-- | Documentation/connector/Makefile | 16 | ||||
| -rw-r--r-- | Documentation/connector/cn_test.c | 202 | ||||
| -rw-r--r-- | Documentation/connector/connector.txt | 181 | ||||
| -rw-r--r-- | Documentation/connector/ucon.c | 250 |
5 files changed, 650 insertions, 0 deletions
diff --git a/Documentation/connector/.gitignore b/Documentation/connector/.gitignore new file mode 100644 index 00000000..d2b9c32a --- /dev/null +++ b/Documentation/connector/.gitignore @@ -0,0 +1 @@ +ucon diff --git a/Documentation/connector/Makefile b/Documentation/connector/Makefile new file mode 100644 index 00000000..d98e4df9 --- /dev/null +++ b/Documentation/connector/Makefile @@ -0,0 +1,16 @@ +ifneq ($(CONFIG_CONNECTOR),) +obj-m += cn_test.o +endif + +# List of programs to build +hostprogs-y := ucon + +# Tell kbuild to always build the programs +always := $(hostprogs-y) + +HOSTCFLAGS_ucon.o += -I$(objtree)/usr/include + +all: modules + +modules clean: + $(MAKE) -C ../.. SUBDIRS=$(PWD) $@ diff --git a/Documentation/connector/cn_test.c b/Documentation/connector/cn_test.c new file mode 100644 index 00000000..77645947 --- /dev/null +++ b/Documentation/connector/cn_test.c @@ -0,0 +1,202 @@ +/* + * cn_test.c + * + * 2004+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net> + * All rights reserved. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ + +#define pr_fmt(fmt) "cn_test: " fmt + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/moduleparam.h> +#include <linux/skbuff.h> +#include <linux/slab.h> +#include <linux/timer.h> + +#include <linux/connector.h> + +static struct cb_id cn_test_id = { CN_NETLINK_USERS + 3, 0x456 }; +static char cn_test_name[] = "cn_test"; +static struct sock *nls; +static struct timer_list cn_test_timer; + +static void cn_test_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp) +{ + pr_info("%s: %lu: idx=%x, val=%x, seq=%u, ack=%u, len=%d: %s.\n", + __func__, jiffies, msg->id.idx, msg->id.val, + msg->seq, msg->ack, msg->len, + msg->len ? (char *)msg->data : ""); +} + +/* + * Do not remove this function even if no one is using it as + * this is an example of how to get notifications about new + * connector user registration + */ +#if 0 +static int cn_test_want_notify(void) +{ + struct cn_ctl_msg *ctl; + struct cn_notify_req *req; + struct cn_msg *msg = NULL; + int size, size0; + struct sk_buff *skb; + struct nlmsghdr *nlh; + u32 group = 1; + + size0 = sizeof(*msg) + sizeof(*ctl) + 3 * sizeof(*req); + + size = NLMSG_SPACE(size0); + + skb = alloc_skb(size, GFP_ATOMIC); + if (!skb) { + pr_err("failed to allocate new skb with size=%u\n", size); + return -ENOMEM; + } + + nlh = NLMSG_PUT(skb, 0, 0x123, NLMSG_DONE, size - sizeof(*nlh)); + + msg = (struct cn_msg *)NLMSG_DATA(nlh); + + memset(msg, 0, size0); + + msg->id.idx = -1; + msg->id.val = -1; + msg->seq = 0x123; + msg->ack = 0x345; + msg->len = size0 - sizeof(*msg); + + ctl = (struct cn_ctl_msg *)(msg + 1); + + ctl->idx_notify_num = 1; + ctl->val_notify_num = 2; + ctl->group = group; + ctl->len = msg->len - sizeof(*ctl); + + req = (struct cn_notify_req *)(ctl + 1); + + /* + * Idx. + */ + req->first = cn_test_id.idx; + req->range = 10; + + /* + * Val 0. + */ + req++; + req->first = cn_test_id.val; + req->range = 10; + + /* + * Val 1. + */ + req++; + req->first = cn_test_id.val + 20; + req->range = 10; + + NETLINK_CB(skb).dst_group = ctl->group; + //netlink_broadcast(nls, skb, 0, ctl->group, GFP_ATOMIC); + netlink_unicast(nls, skb, 0, 0); + + pr_info("request was sent: group=0x%x\n", ctl->group); + + return 0; + +nlmsg_failure: + pr_err("failed to send %u.%u\n", msg->seq, msg->ack); + kfree_skb(skb); + return -EINVAL; +} +#endif + +static u32 cn_test_timer_counter; +static void cn_test_timer_func(unsigned long __data) +{ + struct cn_msg *m; + char data[32]; + + pr_debug("%s: timer fired with data %lu\n", __func__, __data); + + m = kzalloc(sizeof(*m) + sizeof(data), GFP_ATOMIC); + if (m) { + + memcpy(&m->id, &cn_test_id, sizeof(m->id)); + m->seq = cn_test_timer_counter; + m->len = sizeof(data); + + m->len = + scnprintf(data, sizeof(data), "counter = %u", + cn_test_timer_counter) + 1; + + memcpy(m + 1, data, m->len); + + cn_netlink_send(m, 0, GFP_ATOMIC); + kfree(m); + } + + cn_test_timer_counter++; + + mod_timer(&cn_test_timer, jiffies + msecs_to_jiffies(1000)); +} + +static int cn_test_init(void) +{ + int err; + + err = cn_add_callback(&cn_test_id, cn_test_name, cn_test_callback); + if (err) + goto err_out; + cn_test_id.val++; + err = cn_add_callback(&cn_test_id, cn_test_name, cn_test_callback); + if (err) { + cn_del_callback(&cn_test_id); + goto err_out; + } + + setup_timer(&cn_test_timer, cn_test_timer_func, 0); + mod_timer(&cn_test_timer, jiffies + msecs_to_jiffies(1000)); + + pr_info("initialized with id={%u.%u}\n", + cn_test_id.idx, cn_test_id.val); + + return 0; + + err_out: + if (nls && nls->sk_socket) + sock_release(nls->sk_socket); + + return err; +} + +static void cn_test_fini(void) +{ + del_timer_sync(&cn_test_timer); + cn_del_callback(&cn_test_id); + cn_test_id.val--; + cn_del_callback(&cn_test_id); + if (nls && nls->sk_socket) + sock_release(nls->sk_socket); +} + +module_init(cn_test_init); +module_exit(cn_test_fini); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Evgeniy Polyakov <zbr@ioremap.net>"); +MODULE_DESCRIPTION("Connector's test module"); diff --git a/Documentation/connector/connector.txt b/Documentation/connector/connector.txt new file mode 100644 index 00000000..e5c5f5e6 --- /dev/null +++ b/Documentation/connector/connector.txt @@ -0,0 +1,181 @@ +/*****************************************/ +Kernel Connector. +/*****************************************/ + +Kernel connector - new netlink based userspace <-> kernel space easy +to use communication module. + +The Connector driver makes it easy to connect various agents using a +netlink based network. One must register a callback and an identifier. +When the driver receives a special netlink message with the appropriate +identifier, the appropriate callback will be called. + +From the userspace point of view it's quite straightforward: + + socket(); + bind(); + send(); + recv(); + +But if kernelspace wants to use the full power of such connections, the +driver writer must create special sockets, must know about struct sk_buff +handling, etc... The Connector driver allows any kernelspace agents to use +netlink based networking for inter-process communication in a significantly +easier way: + +int cn_add_callback(struct cb_id *id, char *name, void (*callback) (struct cn_msg *, struct netlink_skb_parms *)); +void cn_netlink_send(struct cn_msg *msg, u32 __group, int gfp_mask); + +struct cb_id +{ + __u32 idx; + __u32 val; +}; + +idx and val are unique identifiers which must be registered in the +connector.h header for in-kernel usage. void (*callback) (void *) is a +callback function which will be called when a message with above idx.val +is received by the connector core. The argument for that function must +be dereferenced to struct cn_msg *. + +struct cn_msg +{ + struct cb_id id; + + __u32 seq; + __u32 ack; + + __u32 len; /* Length of the following data */ + __u8 data[0]; +}; + +/*****************************************/ +Connector interfaces. +/*****************************************/ + +int cn_add_callback(struct cb_id *id, char *name, void (*callback) (struct cn_msg *, struct netlink_skb_parms *)); + + Registers new callback with connector core. + + struct cb_id *id - unique connector's user identifier. + It must be registered in connector.h for legal in-kernel users. + char *name - connector's callback symbolic name. + void (*callback) (struct cn..) - connector's callback. + cn_msg and the sender's credentials + + +void cn_del_callback(struct cb_id *id); + + Unregisters new callback with connector core. + + struct cb_id *id - unique connector's user identifier. + + +int cn_netlink_send(struct cn_msg *msg, u32 __groups, int gfp_mask); + + Sends message to the specified groups. It can be safely called from + softirq context, but may silently fail under strong memory pressure. + If there are no listeners for given group -ESRCH can be returned. + + struct cn_msg * - message header(with attached data). + u32 __group - destination group. + If __group is zero, then appropriate group will + be searched through all registered connector users, + and message will be delivered to the group which was + created for user with the same ID as in msg. + If __group is not zero, then message will be delivered + to the specified group. + int gfp_mask - GFP mask. + + Note: When registering new callback user, connector core assigns + netlink group to the user which is equal to its id.idx. + +/*****************************************/ +Protocol description. +/*****************************************/ + +The current framework offers a transport layer with fixed headers. The +recommended protocol which uses such a header is as following: + +msg->seq and msg->ack are used to determine message genealogy. When +someone sends a message, they use a locally unique sequence and random +acknowledge number. The sequence number may be copied into +nlmsghdr->nlmsg_seq too. + +The sequence number is incremented with each message sent. + +If you expect a reply to the message, then the sequence number in the +received message MUST be the same as in the original message, and the +acknowledge number MUST be the same + 1. + +If we receive a message and its sequence number is not equal to one we +are expecting, then it is a new message. If we receive a message and +its sequence number is the same as one we are expecting, but its +acknowledge is not equal to the acknowledge number in the original +message + 1, then it is a new message. + +Obviously, the protocol header contains the above id. + +The connector allows event notification in the following form: kernel +driver or userspace process can ask connector to notify it when +selected ids will be turned on or off (registered or unregistered its +callback). It is done by sending a special command to the connector +driver (it also registers itself with id={-1, -1}). + +As example of this usage can be found in the cn_test.c module which +uses the connector to request notification and to send messages. + +/*****************************************/ +Reliability. +/*****************************************/ + +Netlink itself is not a reliable protocol. That means that messages can +be lost due to memory pressure or process' receiving queue overflowed, +so caller is warned that it must be prepared. That is why the struct +cn_msg [main connector's message header] contains u32 seq and u32 ack +fields. + +/*****************************************/ +Userspace usage. +/*****************************************/ + +2.6.14 has a new netlink socket implementation, which by default does not +allow people to send data to netlink groups other than 1. +So, if you wish to use a netlink socket (for example using connector) +with a different group number, the userspace application must subscribe to +that group first. It can be achieved by the following pseudocode: + +s = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_CONNECTOR); + +l_local.nl_family = AF_NETLINK; +l_local.nl_groups = 12345; +l_local.nl_pid = 0; + +if (bind(s, (struct sockaddr *)&l_local, sizeof(struct sockaddr_nl)) == -1) { + perror("bind"); + close(s); + return -1; +} + +{ + int on = l_local.nl_groups; + setsockopt(s, 270, 1, &on, sizeof(on)); +} + +Where 270 above is SOL_NETLINK, and 1 is a NETLINK_ADD_MEMBERSHIP socket +option. To drop a multicast subscription, one should call the above socket +option with the NETLINK_DROP_MEMBERSHIP parameter which is defined as 0. + +2.6.14 netlink code only allows to select a group which is less or equal to +the maximum group number, which is used at netlink_kernel_create() time. +In case of connector it is CN_NETLINK_USERS + 0xf, so if you want to use +group number 12345, you must increment CN_NETLINK_USERS to that number. +Additional 0xf numbers are allocated to be used by non-in-kernel users. + +Due to this limitation, group 0xffffffff does not work now, so one can +not use add/remove connector's group notifications, but as far as I know, +only cn_test.c test module used it. + +Some work in netlink area is still being done, so things can be changed in +2.6.15 timeframe, if it will happen, documentation will be updated for that +kernel. diff --git a/Documentation/connector/ucon.c b/Documentation/connector/ucon.c new file mode 100644 index 00000000..4848db8c --- /dev/null +++ b/Documentation/connector/ucon.c @@ -0,0 +1,250 @@ +/* + * ucon.c + * + * Copyright (c) 2004+ Evgeniy Polyakov <zbr@ioremap.net> + * + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ + +#include <asm/types.h> + +#include <sys/types.h> +#include <sys/socket.h> +#include <sys/poll.h> + +#include <linux/netlink.h> +#include <linux/rtnetlink.h> + +#include <arpa/inet.h> + +#include <stdbool.h> +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> +#include <string.h> +#include <errno.h> +#include <time.h> +#include <getopt.h> + +#include <linux/connector.h> + +#define DEBUG +#define NETLINK_CONNECTOR 11 + +/* Hopefully your userspace connector.h matches this kernel */ +#define CN_TEST_IDX CN_NETLINK_USERS + 3 +#define CN_TEST_VAL 0x456 + +#ifdef DEBUG +#define ulog(f, a...) fprintf(stdout, f, ##a) +#else +#define ulog(f, a...) do {} while (0) +#endif + +static int need_exit; +static __u32 seq; + +static int netlink_send(int s, struct cn_msg *msg) +{ + struct nlmsghdr *nlh; + unsigned int size; + int err; + char buf[128]; + struct cn_msg *m; + + size = NLMSG_SPACE(sizeof(struct cn_msg) + msg->len); + + nlh = (struct nlmsghdr *)buf; + nlh->nlmsg_seq = seq++; + nlh->nlmsg_pid = getpid(); + nlh->nlmsg_type = NLMSG_DONE; + nlh->nlmsg_len = NLMSG_LENGTH(size - sizeof(*nlh)); + nlh->nlmsg_flags = 0; + + m = NLMSG_DATA(nlh); +#if 0 + ulog("%s: [%08x.%08x] len=%u, seq=%u, ack=%u.\n", + __func__, msg->id.idx, msg->id.val, msg->len, msg->seq, msg->ack); +#endif + memcpy(m, msg, sizeof(*m) + msg->len); + + err = send(s, nlh, size, 0); + if (err == -1) + ulog("Failed to send: %s [%d].\n", + strerror(errno), errno); + + return err; +} + +static void usage(void) +{ + printf( + "Usage: ucon [options] [output file]\n" + "\n" + "\t-h\tthis help screen\n" + "\t-s\tsend buffers to the test module\n" + "\n" + "The default behavior of ucon is to subscribe to the test module\n" + "and wait for state messages. Any ones received are dumped to the\n" + "specified output file (or stdout). The test module is assumed to\n" + "have an id of {%u.%u}\n" + "\n" + "If you get no output, then verify the cn_test module id matches\n" + "the expected id above.\n" + , CN_TEST_IDX, CN_TEST_VAL + ); +} + +int main(int argc, char *argv[]) +{ + int s; + char buf[1024]; + int len; + struct nlmsghdr *reply; + struct sockaddr_nl l_local; + struct cn_msg *data; + FILE *out; + time_t tm; + struct pollfd pfd; + bool send_msgs = false; + + while ((s = getopt(argc, argv, "hs")) != -1) { + switch (s) { + case 's': + send_msgs = true; + break; + + case 'h': + usage(); + return 0; + + default: + /* getopt() outputs an error for us */ + usage(); + return 1; + } + } + + if (argc != optind) { + out = fopen(argv[optind], "a+"); + if (!out) { + ulog("Unable to open %s for writing: %s\n", + argv[1], strerror(errno)); + out = stdout; + } + } else + out = stdout; + + memset(buf, 0, sizeof(buf)); + + s = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_CONNECTOR); + if (s == -1) { + perror("socket"); + return -1; + } + + l_local.nl_family = AF_NETLINK; + l_local.nl_groups = -1; /* bitmask of requested groups */ + l_local.nl_pid = 0; + + ulog("subscribing to %u.%u\n", CN_TEST_IDX, CN_TEST_VAL); + + if (bind(s, (struct sockaddr *)&l_local, sizeof(struct sockaddr_nl)) == -1) { + perror("bind"); + close(s); + return -1; + } + +#if 0 + { + int on = 0x57; /* Additional group number */ + setsockopt(s, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &on, sizeof(on)); + } +#endif + if (send_msgs) { + int i, j; + + memset(buf, 0, sizeof(buf)); + + data = (struct cn_msg *)buf; + + data->id.idx = CN_TEST_IDX; + data->id.val = CN_TEST_VAL; + data->seq = seq++; + data->ack = 0; + data->len = 0; + + for (j=0; j<10; ++j) { + for (i=0; i<1000; ++i) { + len = netlink_send(s, data); + } + + ulog("%d messages have been sent to %08x.%08x.\n", i, data->id.idx, data->id.val); + } + + return 0; + } + + + pfd.fd = s; + + while (!need_exit) { + pfd.events = POLLIN; + pfd.revents = 0; + switch (poll(&pfd, 1, -1)) { + case 0: + need_exit = 1; + break; + case -1: + if (errno != EINTR) { + need_exit = 1; + break; + } + continue; + } + if (need_exit) + break; + + memset(buf, 0, sizeof(buf)); + len = recv(s, buf, sizeof(buf), 0); + if (len == -1) { + perror("recv buf"); + close(s); + return -1; + } + reply = (struct nlmsghdr *)buf; + + switch (reply->nlmsg_type) { + case NLMSG_ERROR: + fprintf(out, "Error message received.\n"); + fflush(out); + break; + case NLMSG_DONE: + data = (struct cn_msg *)NLMSG_DATA(reply); + + time(&tm); + fprintf(out, "%.24s : [%x.%x] [%08u.%08u].\n", + ctime(&tm), data->id.idx, data->id.val, data->seq, data->ack); + fflush(out); + break; + default: + break; + } + } + + close(s); + return 0; +} |