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mconsole_user.c
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1 /*
2  * Copyright (C) 2001 Lennert Buytenhek ([email protected])
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 "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 */
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 
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 }