1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * SMB root file system support
4  *
5  * Copyright (c) 2019 Paulo Alcantara <palcantara@suse.de>
6  */
7 #include <linux/init.h>
8 #include <linux/fs.h>
9 #include <linux/types.h>
10 #include <linux/ctype.h>
11 #include <linux/string.h>
12 #include <linux/root_dev.h>
13 #include <linux/kernel.h>
14 #include <linux/in.h>
15 #include <linux/inet.h>
16 #include <net/ipconfig.h>
17 
18 #define DEFAULT_MNT_OPTS \
19 	"vers=1.0,cifsacl,mfsymlinks,rsize=1048576,wsize=65536,uid=0,gid=0," \
20 	"hard,rootfs"
21 
22 static char root_dev[2048] __initdata = "";
23 static char root_opts[1024] __initdata = DEFAULT_MNT_OPTS;
24 
parse_srvaddr(char * start,char * end)25 static __be32 __init parse_srvaddr(char *start, char *end)
26 {
27 	/* TODO: ipv6 support */
28 	char addr[sizeof("aaa.bbb.ccc.ddd")];
29 	int i = 0;
30 
31 	while (start < end && i < sizeof(addr) - 1) {
32 		if (isdigit(*start) || *start == '.')
33 			addr[i++] = *start;
34 		start++;
35 	}
36 	addr[i] = '\0';
37 	return in_aton(addr);
38 }
39 
40 /* cifsroot=//<server-ip>/<share>[,options] */
cifs_root_setup(char * line)41 static int __init cifs_root_setup(char *line)
42 {
43 	char *s;
44 	int len;
45 	__be32 srvaddr = htonl(INADDR_NONE);
46 
47 	ROOT_DEV = Root_CIFS;
48 
49 	if (strlen(line) > 3 && line[0] == '/' && line[1] == '/') {
50 		s = strchr(&line[2], '/');
51 		if (!s || s[1] == '\0')
52 			return 1;
53 
54 		/* make s point to ',' or '\0' at end of line */
55 		s = strchrnul(s, ',');
56 		/* len is strlen(unc) + '\0' */
57 		len = s - line + 1;
58 		if (len > sizeof(root_dev)) {
59 			pr_err("Root-CIFS: UNC path too long\n");
60 			return 1;
61 		}
62 		strscpy(root_dev, line, len);
63 		srvaddr = parse_srvaddr(&line[2], s);
64 		if (*s) {
65 			int n = snprintf(root_opts,
66 					 sizeof(root_opts), "%s,%s",
67 					 DEFAULT_MNT_OPTS, s + 1);
68 			if (n >= sizeof(root_opts)) {
69 				pr_err("Root-CIFS: mount options string too long\n");
70 				root_opts[sizeof(root_opts)-1] = '\0';
71 				return 1;
72 			}
73 		}
74 	}
75 
76 	root_server_addr = srvaddr;
77 
78 	return 1;
79 }
80 
81 __setup("cifsroot=", cifs_root_setup);
82 
cifs_root_data(char ** dev,char ** opts)83 int __init cifs_root_data(char **dev, char **opts)
84 {
85 	if (!root_dev[0] || root_server_addr == htonl(INADDR_NONE)) {
86 		pr_err("Root-CIFS: no SMB server address\n");
87 		return -1;
88 	}
89 
90 	*dev = root_dev;
91 	*opts = root_opts;
92 
93 	return 0;
94 }
95