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 
mconsole_reply_v0(struct mc_request * req,char * reply)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 
mconsole_parse(struct mc_request * req)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 
mconsole_get_request(int fd,struct mc_request * req)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 
mconsole_reply_len(struct mc_request * req,const char * str,int total,int err,int more)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 
mconsole_reply(struct mc_request * req,const char * str,int err,int more)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 
mconsole_unlink_socket(void)171 int mconsole_unlink_socket(void)
172 {
173 	unlink(mconsole_socket_name);
174 	return 0;
175 }
176 
177 static int notify_sock = -1;
178 
mconsole_notify(char * sock_name,int type,const void * data,int len)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 }
220