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/*
* linux/fs/ext4/symlink.c
*
* Only fast symlinks left here - the rest is done by generic code. AV, 1999
*
* Copyright (C) 1992, 1993, 1994, 1995
* Remy Card (card@masi.ibp.fr)
* Laboratoire MASI - Institut Blaise Pascal
* Universite Pierre et Marie Curie (Paris VI)
*
* from
*
* linux/fs/minix/symlink.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*
* ext4 symlink handling code
*/
#include <linux/fs.h>
#include <linux/namei.h>
#include "ext4.h"
#include "xattr.h"
#ifdef CONFIG_EXT4_FS_ENCRYPTION
static void *ext4_follow_link(struct dentry *dentry, struct nameidata *nd)
{
struct page *cpage = NULL;
char *caddr, *paddr = NULL;
struct ext4_str cstr, pstr;
struct inode *inode = d_inode(dentry);
struct ext4_fname_crypto_ctx *ctx = NULL;
struct ext4_encrypted_symlink_data *sd;
loff_t size = min_t(loff_t, i_size_read(inode), PAGE_SIZE - 1);
int res;
u32 plen, max_size = inode->i_sb->s_blocksize;
if (!ext4_encrypted_inode(inode))
return page_follow_link_light(dentry, nd);
ctx = ext4_get_fname_crypto_ctx(inode, inode->i_sb->s_blocksize);
if (IS_ERR(ctx))
return ctx;
if (ext4_inode_is_fast_symlink(inode)) {
caddr = (char *) EXT4_I(inode)->i_data;
max_size = sizeof(EXT4_I(inode)->i_data);
} else {
cpage = read_mapping_page(inode->i_mapping, 0, NULL);
if (IS_ERR(cpage)) {
ext4_put_fname_crypto_ctx(&ctx);
return cpage;
}
caddr = kmap(cpage);
caddr[size] = 0;
}
/* Symlink is encrypted */
sd = (struct ext4_encrypted_symlink_data *)caddr;
cstr.name = sd->encrypted_path;
cstr.len = le32_to_cpu(sd->len);
if ((cstr.len +
sizeof(struct ext4_encrypted_symlink_data) - 1) >
max_size) {
/* Symlink data on the disk is corrupted */
res = -EIO;
goto errout;
}
plen = (cstr.len < EXT4_FNAME_CRYPTO_DIGEST_SIZE*2) ?
EXT4_FNAME_CRYPTO_DIGEST_SIZE*2 : cstr.len;
paddr = kmalloc(plen + 1, GFP_NOFS);
if (!paddr) {
res = -ENOMEM;
goto errout;
}
pstr.name = paddr;
res = _ext4_fname_disk_to_usr(ctx, &cstr, &pstr);
if (res < 0)
goto errout;
/* Null-terminate the name */
if (res <= plen)
paddr[res] = '\0';
nd_set_link(nd, paddr);
ext4_put_fname_crypto_ctx(&ctx);
if (cpage) {
kunmap(cpage);
page_cache_release(cpage);
}
return NULL;
errout:
ext4_put_fname_crypto_ctx(&ctx);
if (cpage) {
kunmap(cpage);
page_cache_release(cpage);
}
kfree(paddr);
return ERR_PTR(res);
}
static void ext4_put_link(struct dentry *dentry, struct nameidata *nd,
void *cookie)
{
struct page *page = cookie;
if (!page) {
kfree(nd_get_link(nd));
} else {
kunmap(page);
page_cache_release(page);
}
}
#endif
static void *ext4_follow_fast_link(struct dentry *dentry, struct nameidata *nd)
{
struct ext4_inode_info *ei = EXT4_I(d_inode(dentry));
nd_set_link(nd, (char *) ei->i_data);
return NULL;
}
const struct inode_operations ext4_symlink_inode_operations = {
.readlink = generic_readlink,
#ifdef CONFIG_EXT4_FS_ENCRYPTION
.follow_link = ext4_follow_link,
.put_link = ext4_put_link,
#else
.follow_link = page_follow_link_light,
.put_link = page_put_link,
#endif
.setattr = ext4_setattr,
.setxattr = generic_setxattr,
.getxattr = generic_getxattr,
.listxattr = ext4_listxattr,
.removexattr = generic_removexattr,
};
const struct inode_operations ext4_fast_symlink_inode_operations = {
.readlink = generic_readlink,
.follow_link = ext4_follow_fast_link,
.setattr = ext4_setattr,
.setxattr = generic_setxattr,
.getxattr = generic_getxattr,
.listxattr = ext4_listxattr,
.removexattr = generic_removexattr,
};
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