eCryptfs: Force RO mount when encrypted view is enabled
The ecryptfs_encrypted_view mount option greatly changes the functionality of an eCryptfs mount. Instead of encrypting and decrypting lower files, it provides a unified view of the encrypted files in the lower filesystem. The presence of the ecryptfs_encrypted_view mount option is intended to force a read-only mount and modifying files is not supported when the feature is in use. See the following commit for more information:e77a56d
[PATCH] eCryptfs: Encrypted passthrough This patch forces the mount to be read-only when the ecryptfs_encrypted_view mount option is specified by setting the MS_RDONLY flag on the superblock. Additionally, this patch removes some broken logic in ecryptfs_open() that attempted to prevent modifications of files when the encrypted view feature was in use. The check in ecryptfs_open() was not sufficient to prevent file modifications using system calls that do not operate on a file descriptor. Signed-off-by: Tyler Hicks <tyhicks@canonical.com> Reported-by: Priya Bansal <p.bansal@samsung.com> Cc: stable@vger.kernel.org # v2.6.21+:e77a56d
[PATCH] eCryptfs: Encrypted passthrough
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@ -190,23 +190,11 @@ static int ecryptfs_open(struct inode *inode, struct file *file)
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{
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int rc = 0;
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struct ecryptfs_crypt_stat *crypt_stat = NULL;
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struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
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struct dentry *ecryptfs_dentry = file->f_path.dentry;
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/* Private value of ecryptfs_dentry allocated in
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* ecryptfs_lookup() */
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struct ecryptfs_file_info *file_info;
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mount_crypt_stat = &ecryptfs_superblock_to_private(
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ecryptfs_dentry->d_sb)->mount_crypt_stat;
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if ((mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
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&& ((file->f_flags & O_WRONLY) || (file->f_flags & O_RDWR)
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|| (file->f_flags & O_CREAT) || (file->f_flags & O_TRUNC)
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|| (file->f_flags & O_APPEND))) {
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printk(KERN_WARNING "Mount has encrypted view enabled; "
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"files may only be read\n");
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rc = -EPERM;
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goto out;
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}
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/* Released in ecryptfs_release or end of function if failure */
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file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL);
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ecryptfs_set_file_private(file, file_info);
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@ -493,6 +493,7 @@ static struct dentry *ecryptfs_mount(struct file_system_type *fs_type, int flags
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{
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struct super_block *s;
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struct ecryptfs_sb_info *sbi;
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struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
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struct ecryptfs_dentry_info *root_info;
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const char *err = "Getting sb failed";
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struct inode *inode;
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@ -511,6 +512,7 @@ static struct dentry *ecryptfs_mount(struct file_system_type *fs_type, int flags
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err = "Error parsing options";
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goto out;
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}
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mount_crypt_stat = &sbi->mount_crypt_stat;
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s = sget(fs_type, NULL, set_anon_super, flags, NULL);
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if (IS_ERR(s)) {
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@ -557,11 +559,19 @@ static struct dentry *ecryptfs_mount(struct file_system_type *fs_type, int flags
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/**
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* Set the POSIX ACL flag based on whether they're enabled in the lower
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* mount. Force a read-only eCryptfs mount if the lower mount is ro.
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* Allow a ro eCryptfs mount even when the lower mount is rw.
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* mount.
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*/
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s->s_flags = flags & ~MS_POSIXACL;
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s->s_flags |= path.dentry->d_sb->s_flags & (MS_RDONLY | MS_POSIXACL);
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s->s_flags |= path.dentry->d_sb->s_flags & MS_POSIXACL;
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/**
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* Force a read-only eCryptfs mount when:
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* 1) The lower mount is ro
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* 2) The ecryptfs_encrypted_view mount option is specified
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*/
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if (path.dentry->d_sb->s_flags & MS_RDONLY ||
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mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
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s->s_flags |= MS_RDONLY;
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s->s_maxbytes = path.dentry->d_sb->s_maxbytes;
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s->s_blocksize = path.dentry->d_sb->s_blocksize;
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