eCryptfs: do not try to open device files on mknod

When creating device nodes, eCryptfs needs to delay actually opening the lower
persistent file until an application tries to open.  Device handles may not be
backed by anything when they first come into existence.

[Valdis.Kletnieks@vt.edu: build fix]
Signed-off-by: Michael Halcrow <mhalcrow@us.ibm.com>
Cc: <Valdis.Kletnieks@vt.edu}
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/ecryptfs/ecryptfs_kernel.h b/fs/ecryptfs/ecryptfs_kernel.h
index b4a0cccfdd7c7302e3eb9795c9f5f4dee64a9433..b0727f91454efa5a6440936723ec4c83076882e8 100644 (file)
--- a/fs/ecryptfs/ecryptfs_kernel.h
+++ b/fs/ecryptfs/ecryptfs_kernel.h
@@ -235,6 +235,7 @@ struct ecryptfs_crypt_stat {
 #define ECRYPTFS_METADATA_IN_XATTR  0x00000100
 #define ECRYPTFS_VIEW_AS_ENCRYPTED  0x00000200
 #define ECRYPTFS_KEY_SET            0x00000400
+#define ECRYPTFS_DELAY_PERSISTENT   0x00000800
        u32 flags;
        unsigned int file_version;
        size_t iv_bytes;
@@ -574,9 +575,11 @@ struct ecryptfs_open_req {
        struct list_head kthread_ctl_list;
 };
 
+#define ECRYPTFS_INTERPOSE_FLAG_D_ADD                 0x00000001
+#define ECRYPTFS_INTERPOSE_FLAG_DELAY_PERSISTENT_FILE 0x00000002
 int ecryptfs_interpose(struct dentry *hidden_dentry,
                       struct dentry *this_dentry, struct super_block *sb,
-                      int flag);
+                      u32 flags);
 int ecryptfs_fill_zeros(struct file *file, loff_t new_length);
 int ecryptfs_decode_filename(struct ecryptfs_crypt_stat *crypt_stat,
                             const char *name, int length,
@@ -709,5 +712,6 @@ void ecryptfs_destroy_kthread(void);
 int ecryptfs_privileged_open(struct file **lower_file,
                             struct dentry *lower_dentry,
                             struct vfsmount *lower_mnt);
+int ecryptfs_init_persistent_file(struct dentry *ecryptfs_dentry);
 
 #endif /* #ifndef ECRYPTFS_KERNEL_H */

diff --git a/fs/ecryptfs/file.c b/fs/ecryptfs/file.c
index f0be29051528024d375057cfb6f39fc43568878b..2c2d60df3f607e99abc81d3caf1579794f32e5e3 100644 (file)
--- a/fs/ecryptfs/file.c
+++ b/fs/ecryptfs/file.c
@@ -199,6 +199,20 @@ static int ecryptfs_open(struct inode *inode, struct file *file)
                       "file must hence be opened RO\n", __func__);
                goto out;
        }
+       if (!ecryptfs_inode_to_private(inode)->lower_file) {
+               BUG_ON(!(crypt_stat->flags & ECRYPTFS_DELAY_PERSISTENT));
+               mutex_lock(&crypt_stat->cs_mutex);
+               crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
+               mutex_unlock(&crypt_stat->cs_mutex);
+               rc = ecryptfs_init_persistent_file(ecryptfs_dentry);
+               if (rc) {
+                       printk(KERN_ERR "%s: Error attempting to initialize "
+                              "the persistent file for the dentry with name "
+                              "[%s]; rc = [%d]\n", __func__,
+                              ecryptfs_dentry->d_name.name, rc);
+                       goto out;
+               }
+       }
        ecryptfs_set_file_lower(
                file, ecryptfs_inode_to_private(inode)->lower_file);
        if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) {

diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index 7315547193ea7e832f9de89f29d6545a1ec720ee..26090878c930ba0a900a08ee54dee58eea7555fd 100644 (file)
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -308,7 +308,8 @@ static struct dentry *ecryptfs_lookup(struct inode *dir, struct dentry *dentry,
                d_add(dentry, NULL);
                goto out;
        }
-       rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb, 1);
+       rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb,
+                               ECRYPTFS_INTERPOSE_FLAG_D_ADD);
        if (rc) {
                ecryptfs_printk(KERN_ERR, "Error interposing\n");
                goto out_dput;
@@ -537,7 +538,8 @@ ecryptfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
        rc = vfs_mknod(lower_dir_dentry->d_inode, lower_dentry, mode, dev);
        if (rc || !lower_dentry->d_inode)
                goto out;
-       rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb, 0);
+       rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb,
+                               ECRYPTFS_INTERPOSE_FLAG_DELAY_PERSISTENT_FILE);
        if (rc)
                goto out;
        fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);

diff --git a/fs/ecryptfs/main.c b/fs/ecryptfs/main.c
index 10475d93ff537a83fb39bebf01f9fdf39735e11c..ee4f84b204106aa3b2c4ce6827212f754650b663 100644 (file)
--- a/fs/ecryptfs/main.c
+++ b/fs/ecryptfs/main.c
@@ -117,7 +117,7 @@ void __ecryptfs_printk(const char *fmt, ...)
  *
  * Returns zero on success; non-zero otherwise
  */
-static int ecryptfs_init_persistent_file(struct dentry *ecryptfs_dentry)
+int ecryptfs_init_persistent_file(struct dentry *ecryptfs_dentry)
 {
        struct ecryptfs_inode_info *inode_info =
                ecryptfs_inode_to_private(ecryptfs_dentry->d_inode);
@@ -149,14 +149,14 @@ static int ecryptfs_init_persistent_file(struct dentry *ecryptfs_dentry)
  * @lower_dentry: Existing dentry in the lower filesystem
  * @dentry: ecryptfs' dentry
  * @sb: ecryptfs's super_block
- * @flag: If set to true, then d_add is called, else d_instantiate is called
+ * @flags: flags to govern behavior of interpose procedure
  *
  * Interposes upper and lower dentries.
  *
  * Returns zero on success; non-zero otherwise
  */
 int ecryptfs_interpose(struct dentry *lower_dentry, struct dentry *dentry,
-                      struct super_block *sb, int flag)
+                      struct super_block *sb, u32 flags)
 {
        struct inode *lower_inode;
        struct inode *inode;
@@ -193,7 +193,7 @@ int ecryptfs_interpose(struct dentry *lower_dentry, struct dentry *dentry,
                init_special_inode(inode, lower_inode->i_mode,
                                   lower_inode->i_rdev);
        dentry->d_op = &ecryptfs_dops;
-       if (flag)
+       if (flags & ECRYPTFS_INTERPOSE_FLAG_D_ADD)
                d_add(dentry, inode);
        else
                d_instantiate(dentry, inode);
@@ -201,12 +201,21 @@ int ecryptfs_interpose(struct dentry *lower_dentry, struct dentry *dentry,
        /* This size will be overwritten for real files w/ headers and
         * other metadata */
        fsstack_copy_inode_size(inode, lower_inode);
-       rc = ecryptfs_init_persistent_file(dentry);
-       if (rc) {
-               printk(KERN_ERR "%s: Error attempting to initialize the "
-                      "persistent file for the dentry with name [%s]; "
-                      "rc = [%d]\n", __func__, dentry->d_name.name, rc);
-               goto out;
+       if (!(flags & ECRYPTFS_INTERPOSE_FLAG_DELAY_PERSISTENT_FILE)) {
+               rc = ecryptfs_init_persistent_file(dentry);
+               if (rc) {
+                       printk(KERN_ERR "%s: Error attempting to initialize "
+                              "the persistent file for the dentry with name "
+                              "[%s]; rc = [%d]\n", __func__,
+                              dentry->d_name.name, rc);
+                       goto out;
+               }
+       } else {
+               struct ecryptfs_inode_info *inode_info =
+                       ecryptfs_inode_to_private(dentry->d_inode);
+
+               inode_info->lower_file = NULL;
+               inode_info->crypt_stat.flags |= ECRYPTFS_DELAY_PERSISTENT;
        }
 out:
        return rc;