mconsole_user.c

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/*
 * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org)
 * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Licensed under the GPL
 */

#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/uio.h>
#include <sys/un.h>
#include "mconsole.h"

static struct mconsole_command commands[] = {
    /*
     * With uts namespaces, uts information becomes process-specific, so
     * we need a process context.  If we try handling this in interrupt
     * context, we may hit an exiting process without a valid uts
     * namespace.
     */
    { "version", mconsole_version, MCONSOLE_PROC },
    { "halt", mconsole_halt, MCONSOLE_PROC },
    { "reboot", mconsole_reboot, MCONSOLE_PROC },
    { "config", mconsole_config, MCONSOLE_PROC },
    { "remove", mconsole_remove, MCONSOLE_PROC },
    { "sysrq", mconsole_sysrq, MCONSOLE_INTR },
    { "help", mconsole_help, MCONSOLE_INTR },
    { "cad", mconsole_cad, MCONSOLE_INTR },
    { "stop", mconsole_stop, MCONSOLE_PROC },
    { "go", mconsole_go, MCONSOLE_INTR },
    { "log", mconsole_log, MCONSOLE_INTR },
    { "proc", mconsole_proc, MCONSOLE_PROC },
    { "stack", mconsole_stack, MCONSOLE_INTR },
};

/* Initialized in mconsole_init, which is an initcall */
char mconsole_socket_name[256];

static int mconsole_reply_v0(struct mc_request *req, char *reply)
{
    struct iovec iov;
    struct msghdr msg;

    iov.iov_base = reply;
    iov.iov_len = strlen(reply);

    msg.msg_name = &(req->origin);
    msg.msg_namelen = req->originlen;
    msg.msg_iov = &iov;
    msg.msg_iovlen = 1;
    msg.msg_control = NULL;
    msg.msg_controllen = 0;
    msg.msg_flags = 0;

    return sendmsg(req->originating_fd, &msg, 0);
}

static struct mconsole_command *mconsole_parse(struct mc_request *req)
{
    struct mconsole_command *cmd;
    int i;

    for (i = 0; i < ARRAY_SIZE(commands); i++) {
        cmd = &commands[i];
        if (!strncmp(req->request.data, cmd->command,
                strlen(cmd->command))) {
            return cmd;
        }
    }
    return NULL;
}

#define MIN(a,b) ((a)<(b) ? (a):(b))

#define STRINGX(x) #x
#define STRING(x) STRINGX(x)

int mconsole_get_request(int fd, struct mc_request *req)
{
    int len;

    req->originlen = sizeof(req->origin);
    req->len = recvfrom(fd, &req->request, sizeof(req->request), 0,
                (struct sockaddr *) req->origin, &req->originlen);
    if (req->len < 0)
        return 0;

    req->originating_fd = fd;

    if (req->request.magic != MCONSOLE_MAGIC) {
        /* Unversioned request */
        len = MIN(sizeof(req->request.data) - 1,
              strlen((char *) &req->request));
        memmove(req->request.data, &req->request, len);
        req->request.data[len] = '\0';

        req->request.magic = MCONSOLE_MAGIC;
        req->request.version = 0;
        req->request.len = len;

        mconsole_reply_v0(req, "ERR Version 0 mconsole clients are "
                  "not supported by this driver");
        return 0;
    }

    if (req->request.len >= MCONSOLE_MAX_DATA) {
        mconsole_reply(req, "Request too large", 1, 0);
        return 0;
    }
    if (req->request.version != MCONSOLE_VERSION) {
        mconsole_reply(req, "This driver only supports version "
                   STRING(MCONSOLE_VERSION) " clients", 1, 0);
    }

    req->request.data[req->request.len] = '\0';
    req->cmd = mconsole_parse(req);
    if (req->cmd == NULL) {
        mconsole_reply(req, "Unknown command", 1, 0);
        return 0;
    }

    return 1;
}

int mconsole_reply_len(struct mc_request *req, const char *str, int total,
               int err, int more)
{
    /*
     * XXX This is a stack consumption problem.  It'd be nice to
     * make it global and serialize access to it, but there are a
     * ton of callers to this function.
     */
    struct mconsole_reply reply;
    int len, n;

    do {
        reply.err = err;

        /* err can only be true on the first packet */
        err = 0;

        len = MIN(total, MCONSOLE_MAX_DATA - 1);

        if (len == total) reply.more = more;
        else reply.more = 1;

        memcpy(reply.data, str, len);
        reply.data[len] = '\0';
        total -= len;
        str += len;
        reply.len = len + 1;

        len = sizeof(reply) + reply.len - sizeof(reply.data);

        n = sendto(req->originating_fd, &reply, len, 0,
               (struct sockaddr *) req->origin, req->originlen);

        if (n < 0)
            return -errno;
    } while (total > 0);
    return 0;
}

int mconsole_reply(struct mc_request *req, const char *str, int err, int more)
{
    return mconsole_reply_len(req, str, strlen(str), err, more);
}


int mconsole_unlink_socket(void)
{
    unlink(mconsole_socket_name);
    return 0;
}

static int notify_sock = -1;

int mconsole_notify(char *sock_name, int type, const void *data, int len)
{
    struct sockaddr_un target;
    struct mconsole_notify packet;
    int n, err = 0;

    lock_notify();
    if (notify_sock < 0) {
        notify_sock = socket(PF_UNIX, SOCK_DGRAM, 0);
        if (notify_sock < 0) {
            err = -errno;
            printk(UM_KERN_ERR "mconsole_notify - socket failed, "
                   "errno = %d\n", errno);
        }
    }
    unlock_notify();

    if (err)
        return err;

    target.sun_family = AF_UNIX;
    strcpy(target.sun_path, sock_name);

    packet.magic = MCONSOLE_MAGIC;
    packet.version = MCONSOLE_VERSION;
    packet.type = type;
    len = (len > sizeof(packet.data)) ? sizeof(packet.data) : len;
    packet.len = len;
    memcpy(packet.data, data, len);

    err = 0;
    len = sizeof(packet) + packet.len - sizeof(packet.data);
    n = sendto(notify_sock, &packet, len, 0, (struct sockaddr *) &target,
           sizeof(target));
    if (n < 0) {
        err = -errno;
        printk(UM_KERN_ERR "mconsole_notify - sendto failed, "
               "errno = %d\n", errno);
    }
    return err;
}