arch/um/drivers/mconsole_user.c

   1 /*
   2  * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org)
   3  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
   4  * Licensed under the GPL
   5  */
   6
   7 #include <errno.h>
   8 #include <string.h>
   9 #include <unistd.h>
  10 #include <sys/socket.h>
  11 #include <sys/uio.h>
  12 #include <sys/un.h>
  13 #include "kern_constants.h"
  14 #include "mconsole.h"
  15 #include "user.h"
  16
  17 static struct mconsole_command commands[] = {
  18         /*
  19          * With uts namespaces, uts information becomes process-specific, so
  20          * we need a process context.  If we try handling this in interrupt
  21          * context, we may hit an exiting process without a valid uts
  22          * namespace.
  23          */
  24         { "version", mconsole_version, MCONSOLE_PROC },
  25         { "halt", mconsole_halt, MCONSOLE_PROC },
  26         { "reboot", mconsole_reboot, MCONSOLE_PROC },
  27         { "config", mconsole_config, MCONSOLE_PROC },
  28         { "remove", mconsole_remove, MCONSOLE_PROC },
  29         { "sysrq", mconsole_sysrq, MCONSOLE_INTR },
  30         { "help", mconsole_help, MCONSOLE_INTR },
  31         { "cad", mconsole_cad, MCONSOLE_INTR },
  32         { "stop", mconsole_stop, MCONSOLE_PROC },
  33         { "go", mconsole_go, MCONSOLE_INTR },
  34         { "log", mconsole_log, MCONSOLE_INTR },
  35         { "proc", mconsole_proc, MCONSOLE_PROC },
  36         { "stack", mconsole_stack, MCONSOLE_INTR },
  37 };
  38
  39 /* Initialized in mconsole_init, which is an initcall */
  40 char mconsole_socket_name[256];
  41
  42 int mconsole_reply_v0(struct mc_request *req, char *reply)
  43 {
  44         struct iovec iov;
  45         struct msghdr msg;
  46
  47         iov.iov_base = reply;
  48         iov.iov_len = strlen(reply);
  49
  50         msg.msg_name = &(req->origin);
  51         msg.msg_namelen = req->originlen;
  52         msg.msg_iov = &iov;
  53         msg.msg_iovlen = 1;
  54         msg.msg_control = NULL;
  55         msg.msg_controllen = 0;
  56         msg.msg_flags = 0;
  57
  58         return sendmsg(req->originating_fd, &msg, 0);
  59 }
  60
  61 static struct mconsole_command *mconsole_parse(struct mc_request *req)
  62 {
  63         struct mconsole_command *cmd;
  64         int i;
  65
  66         for (i = 0; i < ARRAY_SIZE(commands); i++) {
  67                 cmd = &commands[i];
  68                 if (!strncmp(req->request.data, cmd->command,
  69                             strlen(cmd->command))) {
  70                         return cmd;
  71                 }
  72         }
  73         return NULL;
  74 }
  75
  76 #define MIN(a,b) ((a)<(b) ? (a):(b))
  77
  78 #define STRINGX(x) #x
  79 #define STRING(x) STRINGX(x)
  80
  81 int mconsole_get_request(int fd, struct mc_request *req)
  82 {
  83         int len;
  84
  85         req->originlen = sizeof(req->origin);
  86         req->len = recvfrom(fd, &req->request, sizeof(req->request),
  87                             MSG_DONTWAIT, (struct sockaddr *) req->origin,
  88                             &req->originlen);
  89         if (req->len < 0)
  90                 return 0;
  91
  92         req->originating_fd = fd;
  93
  94         if (req->request.magic != MCONSOLE_MAGIC) {
  95                 /* Unversioned request */
  96                 len = MIN(sizeof(req->request.data) - 1,
  97                           strlen((char *) &req->request));
  98                 memmove(req->request.data, &req->request, len);
  99                 req->request.data[len] = '\0';
 100
 101                 req->request.magic = MCONSOLE_MAGIC;
 102                 req->request.version = 0;
 103                 req->request.len = len;
 104
 105                 mconsole_reply_v0(req, "ERR Version 0 mconsole clients are "
 106                                   "not supported by this driver");
 107                 return 0;
 108         }
 109
 110         if (req->request.len >= MCONSOLE_MAX_DATA) {
 111                 mconsole_reply(req, "Request too large", 1, 0);
 112                 return 0;
 113         }
 114         if (req->request.version != MCONSOLE_VERSION) {
 115                 mconsole_reply(req, "This driver only supports version "
 116                                STRING(MCONSOLE_VERSION) " clients", 1, 0);
 117         }
 118
 119         req->request.data[req->request.len] = '\0';
 120         req->cmd = mconsole_parse(req);
 121         if (req->cmd == NULL) {
 122                 mconsole_reply(req, "Unknown command", 1, 0);
 123                 return 0;
 124         }
 125
 126         return 1;
 127 }
 128
 129 int mconsole_reply_len(struct mc_request *req, const char *str, int total,
 130                        int err, int more)
 131 {
 132         /*
 133          * XXX This is a stack consumption problem.  It'd be nice to
 134          * make it global and serialize access to it, but there are a
 135          * ton of callers to this function.
 136          */
 137         struct mconsole_reply reply;
 138         int len, n;
 139
 140         do {
 141                 reply.err = err;
 142
 143                 /* err can only be true on the first packet */
 144                 err = 0;
 145
 146                 len = MIN(total, MCONSOLE_MAX_DATA - 1);
 147
 148                 if (len == total) reply.more = more;
 149                 else reply.more = 1;
 150
 151                 memcpy(reply.data, str, len);
 152                 reply.data[len] = '\0';
 153                 total -= len;
 154                 str += len;
 155                 reply.len = len + 1;
 156
 157                 len = sizeof(reply) + reply.len - sizeof(reply.data);
 158
 159                 n = sendto(req->originating_fd, &reply, len, 0,
 160                            (struct sockaddr *) req->origin, req->originlen);
 161
 162                 if (n < 0)
 163                         return -errno;
 164         } while (total > 0);
 165         return 0;
 166 }
 167
 168 int mconsole_reply(struct mc_request *req, const char *str, int err, int more)
 169 {
 170         return mconsole_reply_len(req, str, strlen(str), err, more);
 171 }
 172
 173
 174 int mconsole_unlink_socket(void)
 175 {
 176         unlink(mconsole_socket_name);
 177         return 0;
 178 }
 179
 180 static int notify_sock = -1;
 181
 182 int mconsole_notify(char *sock_name, int type, const void *data, int len)
 183 {
 184         struct sockaddr_un target;
 185         struct mconsole_notify packet;
 186         int n, err = 0;
 187
 188         lock_notify();
 189         if (notify_sock < 0) {
 190                 notify_sock = socket(PF_UNIX, SOCK_DGRAM, 0);
 191                 if (notify_sock < 0) {
 192                         err = -errno;
 193                         printk(UM_KERN_ERR "mconsole_notify - socket failed, "
 194                                "errno = %d\n", errno);
 195                 }
 196         }
 197         unlock_notify();
 198
 199         if (err)
 200                 return err;
 201
 202         target.sun_family = AF_UNIX;
 203         strcpy(target.sun_path, sock_name);
 204
 205         packet.magic = MCONSOLE_MAGIC;
 206         packet.version = MCONSOLE_VERSION;
 207         packet.type = type;
 208         len = (len > sizeof(packet.data)) ? sizeof(packet.data) : len;
 209         packet.len = len;
 210         memcpy(packet.data, data, len);
 211
 212         err = 0;
 213         len = sizeof(packet) + packet.len - sizeof(packet.data);
 214         n = sendto(notify_sock, &packet, len, 0, (struct sockaddr *) &target,
 215                    sizeof(target));
 216         if (n < 0) {
 217                 err = -errno;
 218                 printk(UM_KERN_ERR "mconsole_notify - sendto failed, "
 219                        "errno = %d\n", errno);
 220         }
 221         return err;
 222 }