arch/um/drivers/mconsole_user.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org)
   4  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
   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 "mconsole.h"
  14
  15 static struct mconsole_command commands[] = {
  16         /*
  17          * With uts namespaces, uts information becomes process-specific, so
  18          * we need a process context.  If we try handling this in interrupt
  19          * context, we may hit an exiting process without a valid uts
  20          * namespace.
  21          */
  22         { "version", mconsole_version, MCONSOLE_PROC },
  23         { "halt", mconsole_halt, MCONSOLE_PROC },
  24         { "reboot", mconsole_reboot, MCONSOLE_PROC },
  25         { "config", mconsole_config, MCONSOLE_PROC },
  26         { "remove", mconsole_remove, MCONSOLE_PROC },
  27         { "sysrq", mconsole_sysrq, MCONSOLE_INTR },
  28         { "help", mconsole_help, MCONSOLE_INTR },
  29         { "cad", mconsole_cad, MCONSOLE_INTR },
  30         { "stop", mconsole_stop, MCONSOLE_PROC },
  31         { "go", mconsole_go, MCONSOLE_INTR },
  32         { "log", mconsole_log, MCONSOLE_INTR },
  33         { "proc", mconsole_proc, MCONSOLE_PROC },
  34         { "stack", mconsole_stack, MCONSOLE_INTR },
  35 };
  36
  37 /* Initialized in mconsole_init, which is an initcall */
  38 char mconsole_socket_name[256];
  39
  40 static int mconsole_reply_v0(struct mc_request *req, char *reply)
  41 {
  42         struct iovec iov;
  43         struct msghdr msg;
  44
  45         iov.iov_base = reply;
  46         iov.iov_len = strlen(reply);
  47
  48         msg.msg_name = &(req->origin);
  49         msg.msg_namelen = req->originlen;
  50         msg.msg_iov = &iov;
  51         msg.msg_iovlen = 1;
  52         msg.msg_control = NULL;
  53         msg.msg_controllen = 0;
  54         msg.msg_flags = 0;
  55
  56         return sendmsg(req->originating_fd, &msg, 0);
  57 }
  58
  59 static struct mconsole_command *mconsole_parse(struct mc_request *req)
  60 {
  61         struct mconsole_command *cmd;
  62         int i;
  63
  64         for (i = 0; i < ARRAY_SIZE(commands); i++) {
  65                 cmd = &commands[i];
  66                 if (!strncmp(req->request.data, cmd->command,
  67                             strlen(cmd->command))) {
  68                         return cmd;
  69                 }
  70         }
  71         return NULL;
  72 }
  73
  74 #define MIN(a,b) ((a)<(b) ? (a):(b))
  75
  76 #define STRINGX(x) #x
  77 #define STRING(x) STRINGX(x)
  78
  79 int mconsole_get_request(int fd, struct mc_request *req)
  80 {
  81         int len;
  82
  83         req->originlen = sizeof(req->origin);
  84         req->len = recvfrom(fd, &req->request, sizeof(req->request), 0,
  85                             (struct sockaddr *) req->origin, &req->originlen);
  86         if (req->len < 0)
  87                 return 0;
  88
  89         req->originating_fd = fd;
  90
  91         if (req->request.magic != MCONSOLE_MAGIC) {
  92                 /* Unversioned request */
  93                 len = MIN(sizeof(req->request.data) - 1,
  94                           strlen((char *) &req->request));
  95                 memmove(req->request.data, &req->request, len);
  96                 req->request.data[len] = '\0';
  97
  98                 req->request.magic = MCONSOLE_MAGIC;
  99                 req->request.version = 0;
 100                 req->request.len = len;
 101
 102                 mconsole_reply_v0(req, "ERR Version 0 mconsole clients are "
 103                                   "not supported by this driver");
 104                 return 0;
 105         }
 106
 107         if (req->request.len >= MCONSOLE_MAX_DATA) {
 108                 mconsole_reply(req, "Request too large", 1, 0);
 109                 return 0;
 110         }
 111         if (req->request.version != MCONSOLE_VERSION) {
 112                 mconsole_reply(req, "This driver only supports version "
 113                                STRING(MCONSOLE_VERSION) " clients", 1, 0);
 114         }
 115
 116         req->request.data[req->request.len] = '\0';
 117         req->cmd = mconsole_parse(req);
 118         if (req->cmd == NULL) {
 119                 mconsole_reply(req, "Unknown command", 1, 0);
 120                 return 0;
 121         }
 122
 123         return 1;
 124 }
 125
 126 int mconsole_reply_len(struct mc_request *req, const char *str, int total,
 127                        int err, int more)
 128 {
 129         /*
 130          * XXX This is a stack consumption problem.  It'd be nice to
 131          * make it global and serialize access to it, but there are a
 132          * ton of callers to this function.
 133          */
 134         struct mconsole_reply reply;
 135         int len, n;
 136
 137         do {
 138                 reply.err = err;
 139
 140                 /* err can only be true on the first packet */
 141                 err = 0;
 142
 143                 len = MIN(total, MCONSOLE_MAX_DATA - 1);
 144
 145                 if (len == total) reply.more = more;
 146                 else reply.more = 1;
 147
 148                 memcpy(reply.data, str, len);
 149                 reply.data[len] = '\0';
 150                 total -= len;
 151                 str += len;
 152                 reply.len = len + 1;
 153
 154                 len = sizeof(reply) + reply.len - sizeof(reply.data);
 155
 156                 n = sendto(req->originating_fd, &reply, len, 0,
 157                            (struct sockaddr *) req->origin, req->originlen);
 158
 159                 if (n < 0)
 160                         return -errno;
 161         } while (total > 0);
 162         return 0;
 163 }
 164
 165 int mconsole_reply(struct mc_request *req, const char *str, int err, int more)
 166 {
 167         return mconsole_reply_len(req, str, strlen(str), err, more);
 168 }
 169
 170
 171 int mconsole_unlink_socket(void)
 172 {
 173         unlink(mconsole_socket_name);
 174         return 0;
 175 }
 176
 177 static int notify_sock = -1;
 178
 179 int mconsole_notify(char *sock_name, int type, const void *data, int len)
 180 {
 181         struct sockaddr_un target;
 182         struct mconsole_notify packet;
 183         int n, err = 0;
 184
 185         lock_notify();
 186         if (notify_sock < 0) {
 187                 notify_sock = socket(PF_UNIX, SOCK_DGRAM, 0);
 188                 if (notify_sock < 0) {
 189                         err = -errno;
 190                         printk(UM_KERN_ERR "mconsole_notify - socket failed, "
 191                                "errno = %d\n", errno);
 192                 }
 193         }
 194         unlock_notify();
 195
 196         if (err)
 197                 return err;
 198
 199         target.sun_family = AF_UNIX;
 200         strcpy(target.sun_path, sock_name);
 201
 202         packet.magic = MCONSOLE_MAGIC;
 203         packet.version = MCONSOLE_VERSION;
 204         packet.type = type;
 205         len = (len > sizeof(packet.data)) ? sizeof(packet.data) : len;
 206         packet.len = len;
 207         memcpy(packet.data, data, len);
 208
 209         err = 0;
 210         len = sizeof(packet) + packet.len - sizeof(packet.data);
 211         n = sendto(notify_sock, &packet, len, 0, (struct sockaddr *) &target,
 212                    sizeof(target));
 213         if (n < 0) {
 214                 err = -errno;
 215                 printk(UM_KERN_ERR "mconsole_notify - sendto failed, "
 216                        "errno = %d\n", errno);
 217         }
 218         return err;
 219 }