From 2aac0cf88681bfa092f731553bc7fbd23516be73 Mon Sep 17 00:00:00 2001 From: Tyler Hicks Date: Fri, 20 Mar 2009 02:23:57 -0500 Subject: [PATCH] eCryptfs: NULL crypt_stat dereference during lookup If ecryptfs_encrypted_view or ecryptfs_xattr_metadata were being specified as mount options, a NULL pointer dereference of crypt_stat was possible during lookup. This patch moves the crypt_stat assignment into ecryptfs_lookup_and_interpose_lower(), ensuring that crypt_stat will not be NULL before we attempt to dereference it. Thanks to Dan Carpenter and his static analysis tool, smatch, for finding this bug. Signed-off-by: Tyler Hicks Acked-by: Dustin Kirkland Cc: Dan Carpenter Cc: Serge Hallyn Signed-off-by: Linus Torvalds --- fs/ecryptfs/crypto.c | 10 ++++++---- fs/ecryptfs/ecryptfs_kernel.h | 1 - fs/ecryptfs/inode.c | 32 ++++++++++++-------------------- 3 files changed, 18 insertions(+), 25 deletions(-) diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c index 75bee99de0f6..8b65f289ee00 100644 --- a/fs/ecryptfs/crypto.c +++ b/fs/ecryptfs/crypto.c @@ -2221,17 +2221,19 @@ int ecryptfs_decode_and_decrypt_filename(char **plaintext_name, struct dentry *ecryptfs_dir_dentry, const char *name, size_t name_size) { + struct ecryptfs_mount_crypt_stat *mount_crypt_stat = + &ecryptfs_superblock_to_private( + ecryptfs_dir_dentry->d_sb)->mount_crypt_stat; char *decoded_name; size_t decoded_name_size; size_t packet_size; int rc = 0; - if ((name_size > ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE) + if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) + && !(mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) + && (name_size > ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE) && (strncmp(name, ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX, ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE) == 0)) { - struct ecryptfs_mount_crypt_stat *mount_crypt_stat = - &ecryptfs_superblock_to_private( - ecryptfs_dir_dentry->d_sb)->mount_crypt_stat; const char *orig_name = name; size_t orig_name_size = name_size; diff --git a/fs/ecryptfs/ecryptfs_kernel.h b/fs/ecryptfs/ecryptfs_kernel.h index eb2267eca1fe..ac749d4d644f 100644 --- a/fs/ecryptfs/ecryptfs_kernel.h +++ b/fs/ecryptfs/ecryptfs_kernel.h @@ -620,7 +620,6 @@ int ecryptfs_interpose(struct dentry *hidden_dentry, u32 flags); int ecryptfs_lookup_and_interpose_lower(struct dentry *ecryptfs_dentry, struct dentry *lower_dentry, - struct ecryptfs_crypt_stat *crypt_stat, struct inode *ecryptfs_dir_inode, struct nameidata *ecryptfs_nd); int ecryptfs_decode_and_decrypt_filename(char **decrypted_name, diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c index 5697899a168d..55b3145b8072 100644 --- a/fs/ecryptfs/inode.c +++ b/fs/ecryptfs/inode.c @@ -246,7 +246,6 @@ out: */ int ecryptfs_lookup_and_interpose_lower(struct dentry *ecryptfs_dentry, struct dentry *lower_dentry, - struct ecryptfs_crypt_stat *crypt_stat, struct inode *ecryptfs_dir_inode, struct nameidata *ecryptfs_nd) { @@ -254,6 +253,7 @@ int ecryptfs_lookup_and_interpose_lower(struct dentry *ecryptfs_dentry, struct vfsmount *lower_mnt; struct inode *lower_inode; struct ecryptfs_mount_crypt_stat *mount_crypt_stat; + struct ecryptfs_crypt_stat *crypt_stat; char *page_virt = NULL; u64 file_size; int rc = 0; @@ -314,6 +314,11 @@ int ecryptfs_lookup_and_interpose_lower(struct dentry *ecryptfs_dentry, goto out_free_kmem; } } + crypt_stat = &ecryptfs_inode_to_private( + ecryptfs_dentry->d_inode)->crypt_stat; + /* TODO: lock for crypt_stat comparison */ + if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) + ecryptfs_set_default_sizes(crypt_stat); rc = ecryptfs_read_and_validate_header_region(page_virt, ecryptfs_dentry->d_inode); if (rc) { @@ -362,9 +367,7 @@ static struct dentry *ecryptfs_lookup(struct inode *ecryptfs_dir_inode, { char *encrypted_and_encoded_name = NULL; size_t encrypted_and_encoded_name_size; - struct ecryptfs_crypt_stat *crypt_stat = NULL; struct ecryptfs_mount_crypt_stat *mount_crypt_stat = NULL; - struct ecryptfs_inode_info *inode_info; struct dentry *lower_dir_dentry, *lower_dentry; int rc = 0; @@ -388,26 +391,15 @@ static struct dentry *ecryptfs_lookup(struct inode *ecryptfs_dir_inode, } if (lower_dentry->d_inode) goto lookup_and_interpose; - inode_info = ecryptfs_inode_to_private(ecryptfs_dentry->d_inode); - if (inode_info) { - crypt_stat = &inode_info->crypt_stat; - /* TODO: lock for crypt_stat comparison */ - if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) - ecryptfs_set_default_sizes(crypt_stat); - } - if (crypt_stat) - mount_crypt_stat = crypt_stat->mount_crypt_stat; - else - mount_crypt_stat = &ecryptfs_superblock_to_private( - ecryptfs_dentry->d_sb)->mount_crypt_stat; - if (!(crypt_stat && (crypt_stat->flags & ECRYPTFS_ENCRYPT_FILENAMES)) - && !(mount_crypt_stat && (mount_crypt_stat->flags - & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES))) + mount_crypt_stat = &ecryptfs_superblock_to_private( + ecryptfs_dentry->d_sb)->mount_crypt_stat; + if (!(mount_crypt_stat + && (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES))) goto lookup_and_interpose; dput(lower_dentry); rc = ecryptfs_encrypt_and_encode_filename( &encrypted_and_encoded_name, &encrypted_and_encoded_name_size, - crypt_stat, mount_crypt_stat, ecryptfs_dentry->d_name.name, + NULL, mount_crypt_stat, ecryptfs_dentry->d_name.name, ecryptfs_dentry->d_name.len); if (rc) { printk(KERN_ERR "%s: Error attempting to encrypt and encode " @@ -426,7 +418,7 @@ static struct dentry *ecryptfs_lookup(struct inode *ecryptfs_dir_inode, } lookup_and_interpose: rc = ecryptfs_lookup_and_interpose_lower(ecryptfs_dentry, lower_dentry, - crypt_stat, ecryptfs_dir_inode, + ecryptfs_dir_inode, ecryptfs_nd); goto out; out_d_drop: -- 2.20.1