2006-10-11 02:20:50 -06:00
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/*
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2006-10-11 02:20:53 -06:00
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* linux/fs/ext4/symlink.c
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2006-10-11 02:20:50 -06:00
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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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2006-10-11 02:20:53 -06:00
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* ext4 symlink handling code
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2006-10-11 02:20:50 -06:00
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*/
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#include <linux/fs.h>
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#include <linux/namei.h>
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2008-04-29 16:13:32 -06:00
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#include "ext4.h"
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2006-10-11 02:20:50 -06:00
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#include "xattr.h"
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2015-11-17 08:20:54 -07:00
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static const char *ext4_encrypted_get_link(struct dentry *dentry,
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2015-12-29 13:58:39 -07:00
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struct inode *inode,
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struct delayed_call *done)
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2015-04-15 23:55:00 -06:00
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{
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struct page *cpage = NULL;
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char *caddr, *paddr = NULL;
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2016-07-10 12:01:03 -06:00
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struct fscrypt_str cstr, pstr;
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struct fscrypt_symlink_data *sd;
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2015-04-15 23:55:00 -06:00
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int res;
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2016-07-10 12:01:03 -06:00
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u32 max_size = inode->i_sb->s_blocksize;
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2015-04-15 23:55:00 -06:00
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2015-11-17 08:20:54 -07:00
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if (!dentry)
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return ERR_PTR(-ECHILD);
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2016-07-10 12:01:03 -06:00
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res = fscrypt_get_encryption_info(inode);
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ext4 crypto: reorganize how we store keys in the inode
This is a pretty massive patch which does a number of different things:
1) The per-inode encryption information is now stored in an allocated
data structure, ext4_crypt_info, instead of directly in the node.
This reduces the size usage of an in-memory inode when it is not
using encryption.
2) We drop the ext4_fname_crypto_ctx entirely, and use the per-inode
encryption structure instead. This remove an unnecessary memory
allocation and free for the fname_crypto_ctx as well as allowing us
to reuse the ctfm in a directory for multiple lookups and file
creations.
3) We also cache the inode's policy information in the ext4_crypt_info
structure so we don't have to continually read it out of the
extended attributes.
4) We now keep the keyring key in the inode's encryption structure
instead of releasing it after we are done using it to derive the
per-inode key. This allows us to test to see if the key has been
revoked; if it has, we prevent the use of the derived key and free
it.
5) When an inode is released (or when the derived key is freed), we
will use memset_explicit() to zero out the derived key, so it's not
left hanging around in memory. This implies that when a user logs
out, it is important to first revoke the key, and then unlink it,
and then finally, to use "echo 3 > /proc/sys/vm/drop_caches" to
release any decrypted pages and dcache entries from the system
caches.
6) All this, and we also shrink the number of lines of code by around
100. :-)
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2015-05-18 11:17:47 -06:00
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if (res)
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return ERR_PTR(res);
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2015-04-15 23:55:00 -06:00
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if (ext4_inode_is_fast_symlink(inode)) {
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2015-04-26 16:48:49 -06:00
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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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2015-04-15 23:55:00 -06:00
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} else {
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cpage = read_mapping_page(inode->i_mapping, 0, NULL);
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ext4 crypto: reorganize how we store keys in the inode
This is a pretty massive patch which does a number of different things:
1) The per-inode encryption information is now stored in an allocated
data structure, ext4_crypt_info, instead of directly in the node.
This reduces the size usage of an in-memory inode when it is not
using encryption.
2) We drop the ext4_fname_crypto_ctx entirely, and use the per-inode
encryption structure instead. This remove an unnecessary memory
allocation and free for the fname_crypto_ctx as well as allowing us
to reuse the ctfm in a directory for multiple lookups and file
creations.
3) We also cache the inode's policy information in the ext4_crypt_info
structure so we don't have to continually read it out of the
extended attributes.
4) We now keep the keyring key in the inode's encryption structure
instead of releasing it after we are done using it to derive the
per-inode key. This allows us to test to see if the key has been
revoked; if it has, we prevent the use of the derived key and free
it.
5) When an inode is released (or when the derived key is freed), we
will use memset_explicit() to zero out the derived key, so it's not
left hanging around in memory. This implies that when a user logs
out, it is important to first revoke the key, and then unlink it,
and then finally, to use "echo 3 > /proc/sys/vm/drop_caches" to
release any decrypted pages and dcache entries from the system
caches.
6) All this, and we also shrink the number of lines of code by around
100. :-)
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2015-05-18 11:17:47 -06:00
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if (IS_ERR(cpage))
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2015-05-02 11:32:22 -06:00
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return ERR_CAST(cpage);
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2015-11-16 23:07:57 -07:00
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caddr = page_address(cpage);
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2015-04-15 23:55:00 -06:00
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}
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/* Symlink is encrypted */
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2016-07-10 12:01:03 -06:00
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sd = (struct fscrypt_symlink_data *)caddr;
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2015-04-15 23:55:00 -06:00
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cstr.name = sd->encrypted_path;
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2015-11-26 13:20:50 -07:00
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cstr.len = le16_to_cpu(sd->len);
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2016-07-10 12:01:03 -06:00
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if ((cstr.len + sizeof(struct fscrypt_symlink_data) - 1) > max_size) {
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2015-04-15 23:55:00 -06:00
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/* Symlink data on the disk is corrupted */
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2015-10-17 14:16:04 -06:00
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res = -EFSCORRUPTED;
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2015-04-15 23:55:00 -06:00
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goto errout;
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}
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2016-07-10 12:01:03 -06:00
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res = fscrypt_fname_alloc_buffer(inode, cstr.len, &pstr);
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if (res)
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2015-04-15 23:55:00 -06:00
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goto errout;
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2016-09-15 11:13:13 -06:00
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paddr = pstr.name;
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2016-07-10 12:01:03 -06:00
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res = fscrypt_fname_disk_to_usr(inode, 0, 0, &cstr, &pstr);
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2016-09-15 15:25:55 -06:00
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if (res)
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2015-04-15 23:55:00 -06:00
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goto errout;
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2016-07-10 12:01:03 -06:00
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2015-04-15 23:55:00 -06:00
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/* Null-terminate the name */
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2016-09-15 15:25:55 -06:00
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paddr[pstr.len] = '\0';
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2015-11-16 23:07:57 -07:00
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if (cpage)
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mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros
PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time
ago with promise that one day it will be possible to implement page
cache with bigger chunks than PAGE_SIZE.
This promise never materialized. And unlikely will.
We have many places where PAGE_CACHE_SIZE assumed to be equal to
PAGE_SIZE. And it's constant source of confusion on whether
PAGE_CACHE_* or PAGE_* constant should be used in a particular case,
especially on the border between fs and mm.
Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much
breakage to be doable.
Let's stop pretending that pages in page cache are special. They are
not.
The changes are pretty straight-forward:
- <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;
- <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;
- PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN};
- page_cache_get() -> get_page();
- page_cache_release() -> put_page();
This patch contains automated changes generated with coccinelle using
script below. For some reason, coccinelle doesn't patch header files.
I've called spatch for them manually.
The only adjustment after coccinelle is revert of changes to
PAGE_CAHCE_ALIGN definition: we are going to drop it later.
There are few places in the code where coccinelle didn't reach. I'll
fix them manually in a separate patch. Comments and documentation also
will be addressed with the separate patch.
virtual patch
@@
expression E;
@@
- E << (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E
@@
expression E;
@@
- E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E
@@
@@
- PAGE_CACHE_SHIFT
+ PAGE_SHIFT
@@
@@
- PAGE_CACHE_SIZE
+ PAGE_SIZE
@@
@@
- PAGE_CACHE_MASK
+ PAGE_MASK
@@
expression E;
@@
- PAGE_CACHE_ALIGN(E)
+ PAGE_ALIGN(E)
@@
expression E;
@@
- page_cache_get(E)
+ get_page(E)
@@
expression E;
@@
- page_cache_release(E)
+ put_page(E)
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-01 06:29:47 -06:00
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put_page(cpage);
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2015-12-29 13:58:39 -07:00
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set_delayed_call(done, kfree_link, paddr);
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return paddr;
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2015-04-15 23:55:00 -06:00
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errout:
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2015-11-16 23:07:57 -07:00
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if (cpage)
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mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros
PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time
ago with promise that one day it will be possible to implement page
cache with bigger chunks than PAGE_SIZE.
This promise never materialized. And unlikely will.
We have many places where PAGE_CACHE_SIZE assumed to be equal to
PAGE_SIZE. And it's constant source of confusion on whether
PAGE_CACHE_* or PAGE_* constant should be used in a particular case,
especially on the border between fs and mm.
Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much
breakage to be doable.
Let's stop pretending that pages in page cache are special. They are
not.
The changes are pretty straight-forward:
- <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;
- <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;
- PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN};
- page_cache_get() -> get_page();
- page_cache_release() -> put_page();
This patch contains automated changes generated with coccinelle using
script below. For some reason, coccinelle doesn't patch header files.
I've called spatch for them manually.
The only adjustment after coccinelle is revert of changes to
PAGE_CAHCE_ALIGN definition: we are going to drop it later.
There are few places in the code where coccinelle didn't reach. I'll
fix them manually in a separate patch. Comments and documentation also
will be addressed with the separate patch.
virtual patch
@@
expression E;
@@
- E << (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E
@@
expression E;
@@
- E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E
@@
@@
- PAGE_CACHE_SHIFT
+ PAGE_SHIFT
@@
@@
- PAGE_CACHE_SIZE
+ PAGE_SIZE
@@
@@
- PAGE_CACHE_MASK
+ PAGE_MASK
@@
expression E;
@@
- PAGE_CACHE_ALIGN(E)
+ PAGE_ALIGN(E)
@@
expression E;
@@
- page_cache_get(E)
+ get_page(E)
@@
expression E;
@@
- page_cache_release(E)
+ put_page(E)
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-01 06:29:47 -06:00
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put_page(cpage);
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2015-04-15 23:55:00 -06:00
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kfree(paddr);
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return ERR_PTR(res);
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}
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2015-04-27 15:51:30 -06:00
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const struct inode_operations ext4_encrypted_symlink_inode_operations = {
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.readlink = generic_readlink,
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2015-11-17 08:20:54 -07:00
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.get_link = ext4_encrypted_get_link,
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2015-04-27 15:51:30 -06:00
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.setattr = ext4_setattr,
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.listxattr = ext4_listxattr,
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};
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2015-04-15 23:55:00 -06:00
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2007-02-12 01:55:38 -07:00
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const struct inode_operations ext4_symlink_inode_operations = {
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2006-10-11 02:20:50 -06:00
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.readlink = generic_readlink,
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2015-11-17 08:20:54 -07:00
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.get_link = page_get_link,
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2010-05-16 00:00:00 -06:00
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.setattr = ext4_setattr,
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2006-10-11 02:20:53 -06:00
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.listxattr = ext4_listxattr,
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2006-10-11 02:20:50 -06:00
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};
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2007-02-12 01:55:38 -07:00
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const struct inode_operations ext4_fast_symlink_inode_operations = {
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2006-10-11 02:20:50 -06:00
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.readlink = generic_readlink,
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2015-11-17 08:20:54 -07:00
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.get_link = simple_get_link,
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2010-05-16 00:00:00 -06:00
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.setattr = ext4_setattr,
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2006-10-11 02:20:53 -06:00
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.listxattr = ext4_listxattr,
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2006-10-11 02:20:50 -06:00
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};
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