eCryptfs: Handle failed metadata read in lookup

When failing to read the lower file's crypto metadata during a lookup,
eCryptfs must continue on without throwing an error. For example, there
may be a plaintext file in the lower mount point that the user wants to
delete through the eCryptfs mount.

If an error is encountered while reading the metadata in lookup(), the
eCryptfs inode's size could be incorrect. We must be sure to reread the
plaintext inode size from the metadata when performing an open() or
setattr(). The metadata is already being read in those paths, so this
adds minimal performance overhead.

This patch introduces a flag which will track whether or not the
plaintext inode size has been read so that an incorrect i_size can be
fixed in the open() or setattr() paths.

BugLink: http://bugs.launchpad.net/bugs/509180

Cc: <stable@kernel.org>
Signed-off-by: Tyler Hicks <tyhicks@linux.vnet.ibm.com>

(backported from 3aeb86ea4cd15f728147a3bd5469a205ada8c767)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Acked-by: Leann Ogasawara <leann.ogasawara@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index bfd8b68..97b0a86 100644 (file)
--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -1452,6 +1452,25 @@ static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
        crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
 }
 
+void ecryptfs_i_size_init(const char *page_virt, struct inode *inode)
+{
+       struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
+       struct ecryptfs_crypt_stat *crypt_stat;
+       u64 file_size;
+
+       crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
+       mount_crypt_stat =
+               &ecryptfs_superblock_to_private(inode->i_sb)->mount_crypt_stat;
+       if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) {
+               file_size = i_size_read(ecryptfs_inode_to_lower(inode));
+               if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
+                       file_size += crypt_stat->metadata_size;
+       } else
+               file_size = get_unaligned_be64(page_virt);
+       i_size_write(inode, (loff_t)file_size);
+       crypt_stat->flags |= ECRYPTFS_I_SIZE_INITIALIZED;
+}
+
 /**
  * ecryptfs_read_headers_virt
  * @page_virt: The virtual address into which to read the headers
@@ -1482,6 +1501,8 @@ static int ecryptfs_read_headers_virt(char *page_virt,
                rc = -EINVAL;
                goto out;
        }
+       if (!(crypt_stat->flags & ECRYPTFS_I_SIZE_INITIALIZED))
+               ecryptfs_i_size_init(page_virt, ecryptfs_dentry->d_inode);
        offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
        rc = ecryptfs_process_flags(crypt_stat, (page_virt + offset),
                                    &bytes_read);

diff --git a/fs/ecryptfs/ecryptfs_kernel.h b/fs/ecryptfs/ecryptfs_kernel.h
index e007534..40efaa7 100644 (file)
--- a/fs/ecryptfs/ecryptfs_kernel.h
+++ b/fs/ecryptfs/ecryptfs_kernel.h
@@ -270,6 +270,7 @@ struct ecryptfs_crypt_stat {
 #define ECRYPTFS_ENCFN_USE_MOUNT_FNEK 0x00001000
 #define ECRYPTFS_ENCFN_USE_FEK        0x00002000
 #define ECRYPTFS_UNLINK_SIGS         0x00004000
+#define ECRYPTFS_I_SIZE_INITIALIZED   0x00008000
        u32 flags;
        unsigned int file_version;
        size_t iv_bytes;
@@ -630,6 +631,7 @@ struct ecryptfs_open_req {
 int ecryptfs_interpose(struct dentry *hidden_dentry,
                       struct dentry *this_dentry, struct super_block *sb,
                       u32 flags);
+void ecryptfs_i_size_init(const char *page_virt, struct inode *inode);
 int ecryptfs_lookup_and_interpose_lower(struct dentry *ecryptfs_dentry,
                                        struct dentry *lower_dentry,
                                        struct inode *ecryptfs_dir_inode);

diff --git a/fs/ecryptfs/file.c b/fs/ecryptfs/file.c
index 7d1050e..d30aac2 100644 (file)
--- a/fs/ecryptfs/file.c
+++ b/fs/ecryptfs/file.c
@@ -211,7 +211,8 @@ static int ecryptfs_open(struct inode *inode, struct file *file)
        if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) {
                ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
                mutex_lock(&crypt_stat->cs_mutex);
-               crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
+               crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED
+                                       | ECRYPTFS_ENCRYPTED);
                mutex_unlock(&crypt_stat->cs_mutex);
                rc = 0;
                goto out;

diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index b592938..274d573 100644 (file)
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -250,10 +250,8 @@ int ecryptfs_lookup_and_interpose_lower(struct dentry *ecryptfs_dentry,
        struct dentry *lower_dir_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;
 
        lower_dir_dentry = lower_dentry->d_parent;
@@ -326,18 +324,7 @@ int ecryptfs_lookup_and_interpose_lower(struct dentry *ecryptfs_dentry,
                }
                crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
        }
-       mount_crypt_stat = &ecryptfs_superblock_to_private(
-               ecryptfs_dentry->d_sb)->mount_crypt_stat;
-       if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) {
-               if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
-                       file_size = (crypt_stat->metadata_size
-                                    + i_size_read(lower_dentry->d_inode));
-               else
-                       file_size = i_size_read(lower_dentry->d_inode);
-       } else {
-               file_size = get_unaligned_be64(page_virt);
-       }
-       i_size_write(ecryptfs_dentry->d_inode, (loff_t)file_size);
+       ecryptfs_i_size_init(page_virt, ecryptfs_dentry->d_inode);
 out_free_kmem:
        kmem_cache_free(ecryptfs_header_cache_2, page_virt);
        goto out;
@@ -951,7 +938,8 @@ static int ecryptfs_setattr(struct dentry *dentry, struct iattr *ia)
                                goto out;
                        }
                        rc = 0;
-                       crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
+                       crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED
+                                               | ECRYPTFS_ENCRYPTED);
                }
        }
        mutex_unlock(&crypt_stat->cs_mutex);