[mirror_ubuntu-bionic-kernel.git] / fs / ext4 / symlink.c

/*
 *  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;

	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, NULL, &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);
}

const struct inode_operations ext4_encrypted_symlink_inode_operations = {
	.readlink	= generic_readlink,
	.follow_link    = ext4_follow_link,
	.put_link       = kfree_put_link,
	.setattr	= ext4_setattr,
	.setxattr	= generic_setxattr,
	.getxattr	= generic_getxattr,
	.listxattr	= ext4_listxattr,
	.removexattr	= generic_removexattr,
};
#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,
	.follow_link	= page_follow_link_light,
	.put_link	= page_put_link,
	.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,
};
Commit	Line	Data
ac27a0ec	1	/*
617ba13b	2	* linux/fs/ext4/symlink.c
ac27a0ec DK	3	*
	4	* Only fast symlinks left here - the rest is done by generic code. AV, 1999
	5	*
	6	* Copyright (C) 1992, 1993, 1994, 1995
	7	* Remy Card (card@masi.ibp.fr)
	8	* Laboratoire MASI - Institut Blaise Pascal
	9	* Universite Pierre et Marie Curie (Paris VI)
	10	*
	11	* from
	12	*
	13	* linux/fs/minix/symlink.c
	14	*
	15	* Copyright (C) 1991, 1992 Linus Torvalds
	16	*
617ba13b	17	* ext4 symlink handling code
ac27a0ec DK	18	*/
	19
	20	#include <linux/fs.h>
ac27a0ec	21	#include <linux/namei.h>
3dcf5451	22	#include "ext4.h"
ac27a0ec DK	23	#include "xattr.h"
ac27a0ec DK	24
f348c252	25	#ifdef CONFIG_EXT4_FS_ENCRYPTION
af5bc92d	26	static void ext4_follow_link(struct dentry dentry, struct nameidata *nd)
f348c252 TT	27	{
	28	struct page *cpage = NULL;
	29	char caddr, paddr = NULL;
	30	struct ext4_str cstr, pstr;
9ec3a646	31	struct inode *inode = d_inode(dentry);
f348c252 TT	32	struct ext4_fname_crypto_ctx *ctx = NULL;
	33	struct ext4_encrypted_symlink_data *sd;
	34	loff_t size = min_t(loff_t, i_size_read(inode), PAGE_SIZE - 1);
	35	int res;
	36	u32 plen, max_size = inode->i_sb->s_blocksize;
	37
f348c252 TT	38	ctx = ext4_get_fname_crypto_ctx(inode, inode->i_sb->s_blocksize);
	39	if (IS_ERR(ctx))
	40	return ctx;
	41
	42	if (ext4_inode_is_fast_symlink(inode)) {
9ec3a646 LT	43	caddr = (char *) EXT4_I(inode)->i_data;
9ec3a646 LT	44	max_size = sizeof(EXT4_I(inode)->i_data);
f348c252 TT	45	} else {
	46	cpage = read_mapping_page(inode->i_mapping, 0, NULL);
	47	if (IS_ERR(cpage)) {
	48	ext4_put_fname_crypto_ctx(&ctx);
	49	return cpage;
	50	}
	51	caddr = kmap(cpage);
	52	caddr[size] = 0;
	53	}
	54
	55	/* Symlink is encrypted */
	56	sd = (struct ext4_encrypted_symlink_data *)caddr;
	57	cstr.name = sd->encrypted_path;
	58	cstr.len = le32_to_cpu(sd->len);
	59	if ((cstr.len +
	60	sizeof(struct ext4_encrypted_symlink_data) - 1) >
	61	max_size) {
	62	/* Symlink data on the disk is corrupted */
	63	res = -EIO;
	64	goto errout;
	65	}
	66	plen = (cstr.len < EXT4_FNAME_CRYPTO_DIGEST_SIZE*2) ?
	67	EXT4_FNAME_CRYPTO_DIGEST_SIZE*2 : cstr.len;
	68	paddr = kmalloc(plen + 1, GFP_NOFS);
	69	if (!paddr) {
	70	res = -ENOMEM;
	71	goto errout;
	72	}
	73	pstr.name = paddr;
5de0b4d0	74	res = _ext4_fname_disk_to_usr(ctx, NULL, &cstr, &pstr);
f348c252 TT	75	if (res < 0)
	76	goto errout;
	77	/* Null-terminate the name */
	78	if (res <= plen)
	79	paddr[res] = '\0';
	80	nd_set_link(nd, paddr);
	81	ext4_put_fname_crypto_ctx(&ctx);
	82	if (cpage) {
	83	kunmap(cpage);
	84	page_cache_release(cpage);
	85	}
	86	return NULL;
	87	errout:
	88	ext4_put_fname_crypto_ctx(&ctx);
	89	if (cpage) {
	90	kunmap(cpage);
	91	page_cache_release(cpage);
	92	}
	93	kfree(paddr);
	94	return ERR_PTR(res);
	95	}
	96
a7a67e8a AV	97	const struct inode_operations ext4_encrypted_symlink_inode_operations = {
	98	.readlink = generic_readlink,
	99	.follow_link = ext4_follow_link,
	100	.put_link = kfree_put_link,
	101	.setattr = ext4_setattr,
	102	.setxattr = generic_setxattr,
	103	.getxattr = generic_getxattr,
	104	.listxattr = ext4_listxattr,
	105	.removexattr = generic_removexattr,
	106	};
f348c252 TT	107	#endif
	108
	109	static void ext4_follow_fast_link(struct dentry dentry, struct nameidata *nd)
ac27a0ec	110	{
2b0143b5	111	struct ext4_inode_info *ei = EXT4_I(d_inode(dentry));
af5bc92d	112	nd_set_link(nd, (char *) ei->i_data);
ac27a0ec DK	113	return NULL;
	114	}
	115
754661f1	116	const struct inode_operations ext4_symlink_inode_operations = {
ac27a0ec DK	117	.readlink = generic_readlink,
	118	.follow_link = page_follow_link_light,
	119	.put_link = page_put_link,
256a4535	120	.setattr = ext4_setattr,
ac27a0ec DK	121	.setxattr = generic_setxattr,
ac27a0ec DK	122	.getxattr = generic_getxattr,
617ba13b	123	.listxattr = ext4_listxattr,
ac27a0ec	124	.removexattr = generic_removexattr,
ac27a0ec DK	125	};
ac27a0ec DK	126
754661f1	127	const struct inode_operations ext4_fast_symlink_inode_operations = {
ac27a0ec	128	.readlink = generic_readlink,
f348c252	129	.follow_link = ext4_follow_fast_link,
256a4535	130	.setattr = ext4_setattr,
ac27a0ec DK	131	.setxattr = generic_setxattr,
ac27a0ec DK	132	.getxattr = generic_getxattr,
617ba13b	133	.listxattr = ext4_listxattr,
ac27a0ec	134	.removexattr = generic_removexattr,
ac27a0ec	135	};