/* * 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, 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); } 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, };