linux/fs/ext4/symlink.c
Eric Biggers 8c4bca10ce ext4: report correct st_size for encrypted symlinks
The stat() family of syscalls report the wrong size for encrypted
symlinks, which has caused breakage in several userspace programs.

Fix this by calling fscrypt_symlink_getattr() after ext4_getattr() for
encrypted symlinks.  This function computes the correct size by reading
and decrypting the symlink target (if it's not already cached).

For more details, see the commit which added fscrypt_symlink_getattr().

Fixes: f348c25232 ("ext4 crypto: add symlink encryption")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210702065350.209646-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
2021-07-25 20:01:06 -07:00

85 lines
2.0 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* 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"
static const char *ext4_encrypted_get_link(struct dentry *dentry,
struct inode *inode,
struct delayed_call *done)
{
struct page *cpage = NULL;
const void *caddr;
unsigned int max_size;
const char *paddr;
if (!dentry)
return ERR_PTR(-ECHILD);
if (ext4_inode_is_fast_symlink(inode)) {
caddr = 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))
return ERR_CAST(cpage);
caddr = page_address(cpage);
max_size = inode->i_sb->s_blocksize;
}
paddr = fscrypt_get_symlink(inode, caddr, max_size, done);
if (cpage)
put_page(cpage);
return paddr;
}
static int ext4_encrypted_symlink_getattr(struct user_namespace *mnt_userns,
const struct path *path,
struct kstat *stat, u32 request_mask,
unsigned int query_flags)
{
ext4_getattr(mnt_userns, path, stat, request_mask, query_flags);
return fscrypt_symlink_getattr(path, stat);
}
const struct inode_operations ext4_encrypted_symlink_inode_operations = {
.get_link = ext4_encrypted_get_link,
.setattr = ext4_setattr,
.getattr = ext4_encrypted_symlink_getattr,
.listxattr = ext4_listxattr,
};
const struct inode_operations ext4_symlink_inode_operations = {
.get_link = page_get_link,
.setattr = ext4_setattr,
.getattr = ext4_getattr,
.listxattr = ext4_listxattr,
};
const struct inode_operations ext4_fast_symlink_inode_operations = {
.get_link = simple_get_link,
.setattr = ext4_setattr,
.getattr = ext4_getattr,
.listxattr = ext4_listxattr,
};