From: Eric Sandeen <sandeen@redhat.com>
Date: Tue, 29 Jul 2008 16:57:21 -0500
Subject: [fs] ecryptfs: delay lower file opens until needed
Message-id: 488F9241.9000205@redhat.com
O-Subject: [RHEL5.3 PATCH 5/5] ecryptfs: delay lower file opens until needed
Bugzilla: 429142
RH-Acked-by: Jarod Wilson <jwilson@redhat.com>

Addresses Bug 429142: RHEL5.2: ecryptfs oops after lower persistent file creation failure

eCryptfs had been opening the lower file on first access of any kind,
even if an open was not being requested.  Aside from inefficiency,
this made things like "mknod newnode c 0 0; rm -f newnode" pretty
unhappy becaues the lower file cannot be opened.  And then, on failure,
ecryptfs managed to mis-count dentry references, and things went downhill
from there.

2 patches follow which, put together, delay all file opens until an
open is actually requested, and also fixes the dentry refcounting
problem on lower file open failure.

From: Michael Halcrow <mhalcrow@us.ibm.com>
Date: Thu, 24 Jul 2008 04:30:07 +0000 (-0700)
Subject: eCryptfs: do not try to open device files on mknod
X-Git-Tag: v2.6.27-rc1~644
X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Ftorvalds%2Flinux-2.6.git;a=commitdiff_plain;h=72b55fffd631a89e5be6fe1b4f2565bc4cd90deb

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 ba641c0..d69e6c1 100644
--- a/fs/ecryptfs/ecryptfs_kernel.h
+++ b/fs/ecryptfs/ecryptfs_kernel.h
@@ -580,9 +580,10 @@ struct ecryptfs_open_req {
 	struct list_head kthread_ctl_list;
 };
 
+#define ECRYPTFS_INTERPOSE_FLAG_D_ADD                 0x00000001
 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,
@@ -710,5 +711,6 @@ 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 91ba641..641e0dd 100644
--- a/fs/ecryptfs/file.c
+++ b/fs/ecryptfs/file.c
@@ -198,6 +198,16 @@ 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) {
+		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 1fb52cd..de9becd 100644
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -189,6 +189,16 @@ static int ecryptfs_initialize_file(struct dentry *ecryptfs_dentry)
 				"context; rc = [%d]\n", rc);
 		goto out;
 	}
+	if (!ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->lower_file) {
+		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;
+		}
+	}
 	rc = ecryptfs_write_metadata(ecryptfs_dentry);
 	if (rc) {
 		printk(KERN_ERR "Error writing headers; rc = [%d]\n", rc);
@@ -308,10 +318,11 @@ 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;
+		goto out;
 	}
 	if (S_ISDIR(lower_inode->i_mode)) {
 		ecryptfs_printk(KERN_DEBUG, "Is a directory; returning\n");
@@ -337,11 +348,21 @@ static struct dentry *ecryptfs_lookup(struct inode *dir, struct dentry *dentry,
 		rc = -ENOMEM;
 		ecryptfs_printk(KERN_ERR,
 				"Cannot ecryptfs_kmalloc a page\n");
-		goto out_dput;
+		goto out;
 	}
 	crypt_stat = &ecryptfs_inode_to_private(dentry->d_inode)->crypt_stat;
 	if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED))
 		ecryptfs_set_default_sizes(crypt_stat);
+	if (!ecryptfs_inode_to_private(dentry->d_inode)->lower_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;
+		}
+	}
 	rc = ecryptfs_read_and_validate_header_region(page_virt,
 						      dentry->d_inode);
 	if (rc) {
diff --git a/fs/ecryptfs/main.c b/fs/ecryptfs/main.c
index 84ed493..3f0220f 100644
--- 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);
@@ -201,13 +201,6 @@ 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;
-	}
 out:
 	return rc;
 }