// SPDX-License-Identifier: GPL-2.0
/*
* linux/fs/nfs/nfs4namespace.c
*
* Copyright (C) 2005 Trond Myklebust <[email protected]>
* - Modified by David Howells <[email protected]>
*
* NFSv4 namespace
*/
#include <linux/module.h>
#include <linux/dcache.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_mount.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/addr.h>
#include <linux/vfs.h>
#include <linux/inet.h>
#include "internal.h"
#include "nfs4_fs.h"
#include "nfs.h"
#include "dns_resolve.h"
#define NFSDBG_FACILITY NFSDBG_VFS
/*
* Work out the length that an NFSv4 path would render to as a standard posix
* path, with a leading slash but no terminating slash.
*/
static ssize_t nfs4_pathname_len(const struct nfs4_pathname *pathname)
{
ssize_t len = 0;
int i;
for (i = 0; i < pathname->ncomponents; i++) {
const struct nfs4_string *component = &pathname->components[i];
if (component->len > NAME_MAX)
goto too_long;
len += 1 + component->len; /* Adding "/foo" */
if (len > PATH_MAX)
goto too_long;
}
return len;
too_long:
return -ENAMETOOLONG;
}
/*
* Convert the NFSv4 pathname components into a standard posix path.
*/
static char *nfs4_pathname_string(const struct nfs4_pathname *pathname,
unsigned short *_len)
{
ssize_t len;
char *buf, *p;
int i;
len = nfs4_pathname_len(pathname);
if (len < 0)
return ERR_PTR(len);
*_len = len;
p = buf = kmalloc(len + 1, GFP_KERNEL);
if (!buf)
return ERR_PTR(-ENOMEM);
for (i = 0; i < pathname->ncomponents; i++) {
const struct nfs4_string *component = &pathname->components[i];
*p++ = '/';
memcpy(p, component->data, component->len);
p += component->len;
}
*p = 0;
return buf;
}
/*
* return the path component of "<server>:<path>"
* nfspath - the "<server>:<path>" string
* end - one past the last char that could contain "<server>:"
* returns NULL on failure
*/
static char *nfs_path_component(const char *nfspath, const char *end)
{
char *p;
if (*nfspath == '[') {
/* parse [] escaped IPv6 addrs */
p = strchr(nfspath, ']');
if (p != NULL && ++p < end && *p == ':')
return p + 1;
} else {
/* otherwise split on first colon */
p = strchr(nfspath, ':');
if (p != NULL && p < end)
return p + 1;
}
return NULL;
}
/*
* Determine the mount path as a string
*/
static char *nfs4_path(struct dentry *dentry, char *buffer, ssize_t buflen)
{
char *limit;
char *path = nfs_path(&limit, dentry, buffer, buflen,
NFS_PATH_CANONICAL);
if (!IS_ERR(path)) {
char *path_component = nfs_path_component(path, limit);
if (path_component)
return path_component;
}
return path;
}
/*
* Check that fs_locations::fs_root [RFC3530 6.3] is a prefix for what we
* believe to be the server path to this dentry
*/
static int nfs4_validate_fspath(struct dentry *dentry,
const struct nfs4_fs_locations *locations,
struct nfs_fs_context *ctx)
{
const char *path;
char *fs_path;
unsigned short len;
char *buf;
int n;
buf = kmalloc(4096, GFP_KERNEL);
if (!buf)
return -ENOMEM;
path = nfs4_path(dentry, buf, 4096);
if (IS_ERR(path)) {
kfree(buf);
return PTR_ERR(path);
}
fs_path = nfs4_pathname_string(&locations->fs_path, &len);
if (IS_ERR(fs_path)) {
kfree(buf);
return PTR_ERR(fs_path);
}
n = strncmp(path, fs_path, len);
kfree(buf);
kfree(fs_path);
if (n != 0) {
dprintk("%s: path %s does not begin with fsroot %s\n",
__func__, path, ctx->nfs_server.export_path);
return -ENOENT;
}
return 0;
}
size_t nfs_parse_server_name(char *string, size_t len, struct sockaddr_storage *ss,
size_t salen, struct net *net, int port)
{
struct sockaddr *sa = (struct sockaddr *)ss;
ssize_t ret;
ret = rpc_pton(net, string, len, sa, salen);
if (ret == 0) {
ret = rpc_uaddr2sockaddr(net, string, len, sa, salen);
if (ret == 0) {
ret = nfs_dns_resolve_name(net, string, len, ss, salen);
if (ret < 0)
ret = 0;
}
} else if (port) {
rpc_set_port(sa, port);
}
return ret;
}
/**
* nfs_find_best_sec - Find a security mechanism supported locally
* @clnt: pointer to rpc_clnt
* @server: NFS server struct
* @flavors: List of security tuples returned by SECINFO procedure
*
* Return an rpc client that uses the first security mechanism in
* "flavors" that is locally supported. The "flavors" array
* is searched in the order returned from the server, per RFC 3530
* recommendation and each flavor is checked for membership in the
* sec= mount option list if it exists.
*
* Return -EPERM if no matching flavor is found in the array.
*
* Please call rpc_shutdown_client() when you are done with this rpc client.
*
*/
static struct rpc_clnt *nfs_find_best_sec(struct rpc_clnt *clnt,
struct nfs_server *server,
struct nfs4_secinfo_flavors *flavors)
{
rpc_authflavor_t pflavor;
struct nfs4_secinfo4 *secinfo;
unsigned int i;
for (i = 0; i < flavors->num_flavors; i++) {
secinfo = &flavors->flavors[i];
switch (secinfo->flavor) {
case RPC_AUTH_NULL:
case RPC_AUTH_UNIX:
case RPC_AUTH_GSS:
pflavor = rpcauth_get_pseudoflavor(secinfo->flavor,
&secinfo->flavor_info);
/* does the pseudoflavor match a sec= mount opt? */
if (pflavor != RPC_AUTH_MAXFLAVOR &&
nfs_auth_info_match(&server->auth_info, pflavor)) {
struct rpc_clnt *new;
struct rpc_cred *cred;
/* Cloning creates an rpc_auth for the flavor */
new = rpc_clone_client_set_auth(clnt, pflavor);
if (IS_ERR(new))
continue;
/**
* Check that the user actually can use the
* flavor. This is mostly for RPC_AUTH_GSS
* where cr_init obtains a gss context
*/
cred = rpcauth_lookupcred(new->cl_auth, 0);
if (IS_ERR(cred)) {
rpc_shutdown_client(new);
continue;
}
put_rpccred(cred);
return new;
}
}
}
return ERR_PTR(-EPERM);
}
/**
* nfs4_negotiate_security - in response to an NFS4ERR_WRONGSEC on lookup,
* return an rpc_clnt that uses the best available security flavor with
* respect to the secinfo flavor list and the sec= mount options.
*
* @clnt: RPC client to clone
* @inode: directory inode
* @name: lookup name
*
* Please call rpc_shutdown_client() when you are done with this rpc client.
*/
struct rpc_clnt *
nfs4_negotiate_security(struct rpc_clnt *clnt, struct inode *inode,
const struct qstr *name)
{
struct page *page;
struct nfs4_secinfo_flavors *flavors;
struct rpc_clnt *new;
int err;
page = alloc_page(GFP_KERNEL);
if (!page)
return ERR_PTR(-ENOMEM);
flavors = page_address(page);
err = nfs4_proc_secinfo(inode, name, flavors);
if (err < 0) {
new = ERR_PTR(err);
goto out;
}
new = nfs_find_best_sec(clnt, NFS_SERVER(inode), flavors);
out:
put_page(page);
return new;
}
static int try_location(struct fs_context *fc,
const struct nfs4_fs_location *location)
{
struct nfs_fs_context *ctx = nfs_fc2context(fc);
unsigned int len, s;
char *export_path, *source, *p;
int ret = -ENOENT;
/* Allocate a buffer big enough to hold any of the hostnames plus a
* terminating char and also a buffer big enough to hold the hostname
* plus a colon plus the path.
*/
len = 0;
for (s = 0; s < location->nservers; s++) {
const struct nfs4_string *buf = &location->servers[s];
if (buf->len > len)
len = buf->len;
}
kfree(ctx->nfs_server.hostname);
ctx->nfs_server.hostname = kmalloc(len + 1, GFP_KERNEL);
if (!ctx->nfs_server.hostname)
return -ENOMEM;
export_path = nfs4_pathname_string(&location->rootpath,
&ctx->nfs_server.export_path_len);
if (IS_ERR(export_path))
return PTR_ERR(export_path);
kfree(ctx->nfs_server.export_path);
ctx->nfs_server.export_path = export_path;
source = kmalloc(len + 1 + ctx->nfs_server.export_path_len + 1,
GFP_KERNEL);
if (!source)
return -ENOMEM;
kfree(fc->source);
fc->source = source;
for (s = 0; s < location->nservers; s++) {
const struct nfs4_string *buf = &location->servers[s];
if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len))
continue;
ctx->nfs_server.addrlen =
nfs_parse_server_name(buf->data, buf->len,
&ctx->nfs_server._address,
sizeof(ctx->nfs_server._address),
fc->net_ns, 0);
if (ctx->nfs_server.addrlen == 0)
continue;
rpc_set_port(&ctx->nfs_server.address, NFS_PORT);
memcpy(ctx->nfs_server.hostname, buf->data, buf->len);
ctx->nfs_server.hostname[buf->len] = '\0';
p = source;
memcpy(p, buf->data, buf->len);
p += buf->len;
*p++ = ':';
memcpy(p, ctx->nfs_server.export_path, ctx->nfs_server.export_path_len);
p += ctx->nfs_server.export_path_len;
*p = 0;
ret = nfs4_get_referral_tree(fc);
if (ret == 0)
return 0;
}
return ret;
}
/**
* nfs_follow_referral - set up mountpoint when hitting a referral on moved error
* @fc: pointer to struct nfs_fs_context
* @locations: array of NFSv4 server location information
*
*/
static int nfs_follow_referral(struct fs_context *fc,
const struct nfs4_fs_locations *locations)
{
struct nfs_fs_context *ctx = nfs_fc2context(fc);
int loc, error;
if (locations == NULL || locations->nlocations <= 0)
return -ENOENT;
dprintk("%s: referral at %pd2\n", __func__, ctx->clone_data.dentry);
/* Ensure fs path is a prefix of current dentry path */
error = nfs4_validate_fspath(ctx->clone_data.dentry, locations, ctx);
if (error < 0)
return error;
error = -ENOENT;
for (loc = 0; loc < locations->nlocations; loc++) {
const struct nfs4_fs_location *location = &locations->locations[loc];
if (location == NULL || location->nservers <= 0 ||
location->rootpath.ncomponents == 0)
continue;
error = try_location(fc, location);
if (error == 0)
return 0;
}
return error;
}
/*
* nfs_do_refmount - handle crossing a referral on server
* @dentry - dentry of referral
*
*/
static int nfs_do_refmount(struct fs_context *fc, struct rpc_clnt *client)
{
struct nfs_fs_context *ctx = nfs_fc2context(fc);
struct dentry *dentry, *parent;
struct nfs4_fs_locations *fs_locations = NULL;
struct page *page;
int err = -ENOMEM;
/* BUG_ON(IS_ROOT(dentry)); */
page = alloc_page(GFP_KERNEL);
if (!page)
return -ENOMEM;
fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
if (!fs_locations)
goto out_free;
fs_locations->fattr = nfs_alloc_fattr();
if (!fs_locations->fattr)
goto out_free_2;
/* Get locations */
dentry = ctx->clone_data.dentry;
parent = dget_parent(dentry);
dprintk("%s: getting locations for %pd2\n",
__func__, dentry);
err = nfs4_proc_fs_locations(client, d_inode(parent), &dentry->d_name, fs_locations, page);
dput(parent);
if (err != 0)
goto out_free_3;
err = -ENOENT;
if (fs_locations->nlocations <= 0 ||
fs_locations->fs_path.ncomponents <= 0)
goto out_free_3;
err = nfs_follow_referral(fc, fs_locations);
out_free_3:
kfree(fs_locations->fattr);
out_free_2:
kfree(fs_locations);
out_free:
__free_page(page);
return err;
}
int nfs4_submount(struct fs_context *fc, struct nfs_server *server)
{
struct nfs_fs_context *ctx = nfs_fc2context(fc);
struct dentry *dentry = ctx->clone_data.dentry;
struct dentry *parent = dget_parent(dentry);
struct inode *dir = d_inode(parent);
struct rpc_clnt *client;
int ret;
/* Look it up again to get its attributes and sec flavor */
client = nfs4_proc_lookup_mountpoint(dir, dentry, ctx->mntfh,
ctx->clone_data.fattr);
dput(parent);
if (IS_ERR(client))
return PTR_ERR(client);
ctx->selected_flavor = client->cl_auth->au_flavor;
if (ctx->clone_data.fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL) {
ret = nfs_do_refmount(fc, client);
} else {
ret = nfs_do_submount(fc);
}
rpc_shutdown_client(client);
return ret;
}
/*
* Try one location from the fs_locations array.
*
* Returns zero on success, or a negative errno value.
*/
static int nfs4_try_replacing_one_location(struct nfs_server *server,
char *page, char *page2,
const struct nfs4_fs_location *location)
{
struct net *net = rpc_net_ns(server->client);
struct sockaddr_storage *sap;
unsigned int s;
size_t salen;
int error;
sap = kmalloc(sizeof(*sap), GFP_KERNEL);
if (sap == NULL)
return -ENOMEM;
error = -ENOENT;
for (s = 0; s < location->nservers; s++) {
const struct nfs4_string *buf = &location->servers[s];
char *hostname;
if (buf->len <= 0 || buf->len > PAGE_SIZE)
continue;
if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len) != NULL)
continue;
salen = nfs_parse_server_name(buf->data, buf->len,
sap, sizeof(*sap), net, 0);
if (salen == 0)
continue;
rpc_set_port((struct sockaddr *)sap, NFS_PORT);
error = -ENOMEM;
hostname = kmemdup_nul(buf->data, buf->len, GFP_KERNEL);
if (hostname == NULL)
break;
error = nfs4_update_server(server, hostname, sap, salen, net);
kfree(hostname);
if (error == 0)
break;
}
kfree(sap);
return error;
}
/**
* nfs4_replace_transport - set up transport to destination server
*
* @server: export being migrated
* @locations: fs_locations array
*
* Returns zero on success, or a negative errno value.
*
* The client tries all the entries in the "locations" array, in the
* order returned by the server, until one works or the end of the
* array is reached.
*/
int nfs4_replace_transport(struct nfs_server *server,
const struct nfs4_fs_locations *locations)
{
char *page = NULL, *page2 = NULL;
int loc, error;
error = -ENOENT;
if (locations == NULL || locations->nlocations <= 0)
goto out;
error = -ENOMEM;
page = (char *) __get_free_page(GFP_USER);
if (!page)
goto out;
page2 = (char *) __get_free_page(GFP_USER);
if (!page2)
goto out;
for (loc = 0; loc < locations->nlocations; loc++) {
const struct nfs4_fs_location *location =
&locations->locations[loc];
if (location == NULL || location->nservers <= 0 ||
location->rootpath.ncomponents == 0)
continue;
error = nfs4_try_replacing_one_location(server, page,
page2, location);
if (error == 0)
break;
}
out:
free_page((unsigned long)page);
free_page((unsigned long)page2);
return error;
}
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