linux/fs/cifs/cifsroot.c

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// SPDX-License-Identifier: GPL-2.0
/*
* SMB root file system support
*
* Copyright (c) 2019 Paulo Alcantara <palcantara@suse.de>
*/
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/types.h>
#include <linux/ctype.h>
#include <linux/string.h>
#include <linux/root_dev.h>
#include <linux/kernel.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <net/ipconfig.h>
#define DEFAULT_MNT_OPTS \
"vers=1.0,cifsacl,mfsymlinks,rsize=1048576,wsize=65536,uid=0,gid=0," \
"hard,rootfs"
static char root_dev[2048] __initdata = "";
static char root_opts[1024] __initdata = DEFAULT_MNT_OPTS;
static __be32 __init parse_srvaddr(char *start, char *end)
{
/* TODO: ipv6 support */
char addr[sizeof("aaa.bbb.ccc.ddd")];
int i = 0;
while (start < end && i < sizeof(addr) - 1) {
if (isdigit(*start) || *start == '.')
addr[i++] = *start;
start++;
}
addr[i] = '\0';
return in_aton(addr);
}
/* cifsroot=//<server-ip>/<share>[,options] */
static int __init cifs_root_setup(char *line)
{
char *s;
int len;
__be32 srvaddr = htonl(INADDR_NONE);
ROOT_DEV = Root_CIFS;
if (strlen(line) > 3 && line[0] == '/' && line[1] == '/') {
s = strchr(&line[2], '/');
if (!s || s[1] == '\0')
return 1;
/* make s point to ',' or '\0' at end of line */
s = strchrnul(s, ',');
/* len is strlen(unc) + '\0' */
len = s - line + 1;
if (len > sizeof(root_dev)) {
printk(KERN_ERR "Root-CIFS: UNC path too long\n");
return 1;
}
strlcpy(root_dev, line, len);
srvaddr = parse_srvaddr(&line[2], s);
if (*s) {
int n = snprintf(root_opts,
sizeof(root_opts), "%s,%s",
DEFAULT_MNT_OPTS, s + 1);
if (n >= sizeof(root_opts)) {
printk(KERN_ERR "Root-CIFS: mount options string too long\n");
root_opts[sizeof(root_opts)-1] = '\0';
return 1;
}
}
}
root_server_addr = srvaddr;
return 1;
}
__setup("cifsroot=", cifs_root_setup);
int __init cifs_root_data(char **dev, char **opts)
{
if (!root_dev[0] || root_server_addr == htonl(INADDR_NONE)) {
printk(KERN_ERR "Root-CIFS: no SMB server address\n");
return -1;
}
*dev = root_dev;
*opts = root_opts;
return 0;
}