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
22static char root_dev[2048] __initdata = "";
23static char root_opts[1024] __initdata = DEFAULT_MNT_OPTS;
24
25static __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] */
41static 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
83int __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