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.

https://bugs.launchpad.net/bugs/509180

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

diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index d2a70a4561f91257fe44d7cb867e9d14ec1ff908..b8d5c8091024cd1a66d8f36cf9d8fde25f3d2052 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 380bee1094c351c415e27ef08b3688bce19dec51..e70282775e2c193f11da232c897f6859a2e4334b 100644 (file)
--- a/fs/ecryptfs/ecryptfs_kernel.h
+++ b/fs/ecryptfs/ecryptfs_kernel.h
@@ -269,6 +269,7 @@ struct ecryptfs_crypt_stat {
 #define ECRYPTFS_ENCFN_USE_MOUNT_FNEK 0x00000800
 #define ECRYPTFS_ENCFN_USE_FEK        0x00001000
 #define ECRYPTFS_UNLINK_SIGS          0x00002000
+#define ECRYPTFS_I_SIZE_INITIALIZED   0x00004000
        u32 flags;
        unsigned int file_version;
        size_t iv_bytes;
@@ -628,6 +629,7 @@ 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 146c4edff70cfc898489830bd85d77548ad33585..566e5472f78c3d6dae8e5008689eef281cba37ab 100644 (file)
--- a/fs/ecryptfs/file.c
+++ b/fs/ecryptfs/file.c
@@ -235,7 +235,8 @@ static int ecryptfs_open(struct inode *inode, struct file *file)
                                goto out_put;
                        }
                        rc = 0;
-                       crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
+                       crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED
+                                              | ECRYPTFS_ENCRYPTED);
                        mutex_unlock(&crypt_stat->cs_mutex);
                        goto out;
                }

diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index f6b388638c3d8fc9da660ea2f308da6f6c27cc33..2c19d362d2d43df09def800c4d72ba678328074b 100644 (file)
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -225,10 +225,8 @@ 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 put_lower = 0, rc = 0;
 
        lower_dir_dentry = lower_dentry->d_parent;
@@ -302,18 +300,7 @@ 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;
@@ -937,7 +924,8 @@ 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);