c936e1ec28
As suggested by Herbert Xu, we shouldn't allocate a new tfm each time we read or write a page. Instead we can use a single tfm hanging off the inode's crypt_info structure for all of our encryption needs for that inode, since the tfm can be used by multiple crypto requests in parallel. Also use cmpxchg() to avoid races that could result in crypt_info structure getting doubly allocated or doubly freed. Signed-off-by: Theodore Ts'o <tytso@mit.edu>
142 lines
3.3 KiB
C
142 lines
3.3 KiB
C
/*
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* linux/fs/ext4/symlink.c
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*
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* Only fast symlinks left here - the rest is done by generic code. AV, 1999
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*
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* Copyright (C) 1992, 1993, 1994, 1995
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* Remy Card (card@masi.ibp.fr)
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* Laboratoire MASI - Institut Blaise Pascal
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* Universite Pierre et Marie Curie (Paris VI)
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*
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* from
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*
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* linux/fs/minix/symlink.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*
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* ext4 symlink handling code
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*/
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#include <linux/fs.h>
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#include <linux/namei.h>
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#include "ext4.h"
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#include "xattr.h"
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#ifdef CONFIG_EXT4_FS_ENCRYPTION
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static void *ext4_follow_link(struct dentry *dentry, struct nameidata *nd)
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{
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struct page *cpage = NULL;
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char *caddr, *paddr = NULL;
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struct ext4_str cstr, pstr;
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struct inode *inode = d_inode(dentry);
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struct ext4_encrypted_symlink_data *sd;
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loff_t size = min_t(loff_t, i_size_read(inode), PAGE_SIZE - 1);
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int res;
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u32 plen, max_size = inode->i_sb->s_blocksize;
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if (!ext4_encrypted_inode(inode))
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return page_follow_link_light(dentry, nd);
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res = ext4_get_encryption_info(inode);
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if (res)
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return ERR_PTR(res);
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if (ext4_inode_is_fast_symlink(inode)) {
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caddr = (char *) EXT4_I(inode)->i_data;
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max_size = sizeof(EXT4_I(inode)->i_data);
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} else {
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cpage = read_mapping_page(inode->i_mapping, 0, NULL);
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if (IS_ERR(cpage))
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return cpage;
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caddr = kmap(cpage);
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caddr[size] = 0;
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}
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/* Symlink is encrypted */
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sd = (struct ext4_encrypted_symlink_data *)caddr;
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cstr.name = sd->encrypted_path;
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cstr.len = le32_to_cpu(sd->len);
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if ((cstr.len +
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sizeof(struct ext4_encrypted_symlink_data) - 1) >
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max_size) {
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/* Symlink data on the disk is corrupted */
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res = -EIO;
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goto errout;
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}
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plen = (cstr.len < EXT4_FNAME_CRYPTO_DIGEST_SIZE*2) ?
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EXT4_FNAME_CRYPTO_DIGEST_SIZE*2 : cstr.len;
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paddr = kmalloc(plen + 1, GFP_NOFS);
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if (!paddr) {
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res = -ENOMEM;
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goto errout;
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}
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pstr.name = paddr;
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pstr.len = plen;
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res = _ext4_fname_disk_to_usr(inode, NULL, &cstr, &pstr);
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if (res < 0)
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goto errout;
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/* Null-terminate the name */
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if (res <= plen)
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paddr[res] = '\0';
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nd_set_link(nd, paddr);
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if (cpage) {
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kunmap(cpage);
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page_cache_release(cpage);
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}
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return NULL;
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errout:
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if (cpage) {
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kunmap(cpage);
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page_cache_release(cpage);
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}
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kfree(paddr);
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return ERR_PTR(res);
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}
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static void ext4_put_link(struct dentry *dentry, struct nameidata *nd,
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void *cookie)
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{
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struct page *page = cookie;
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if (!page) {
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kfree(nd_get_link(nd));
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} else {
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kunmap(page);
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page_cache_release(page);
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}
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}
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#endif
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static void *ext4_follow_fast_link(struct dentry *dentry, struct nameidata *nd)
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{
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struct ext4_inode_info *ei = EXT4_I(d_inode(dentry));
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nd_set_link(nd, (char *) ei->i_data);
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return NULL;
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}
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const struct inode_operations ext4_symlink_inode_operations = {
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.readlink = generic_readlink,
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#ifdef CONFIG_EXT4_FS_ENCRYPTION
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.follow_link = ext4_follow_link,
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.put_link = ext4_put_link,
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#else
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.follow_link = page_follow_link_light,
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.put_link = page_put_link,
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#endif
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.setattr = ext4_setattr,
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.setxattr = generic_setxattr,
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.getxattr = generic_getxattr,
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.listxattr = ext4_listxattr,
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.removexattr = generic_removexattr,
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};
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const struct inode_operations ext4_fast_symlink_inode_operations = {
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.readlink = generic_readlink,
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.follow_link = ext4_follow_fast_link,
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.setattr = ext4_setattr,
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.setxattr = generic_setxattr,
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.getxattr = generic_getxattr,
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.listxattr = ext4_listxattr,
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.removexattr = generic_removexattr,
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};
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