eCryptfs: Filename Encryption: filldir, lookup, and readlink

Make the requisite modifications to ecryptfs_filldir(), ecryptfs_lookup(),
and ecryptfs_readlink() to call out to filename encryption functions.
Propagate filename encryption policy flags from mount-wide crypt_stat to
inode crypt_stat.

Signed-off-by: Michael Halcrow <mhalcrow@us.ibm.com>
Cc: Dustin Kirkland <dustin.kirkland@gmail.com>
Cc: Eric Sandeen <sandeen@redhat.com>
Cc: Tyler Hicks <tchicks@us.ibm.com>
Cc: David Kleikamp <shaggy@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 167 insertions, 127 deletions

diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index 0111906a8877..38309ce94d71 100644
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -228,8 +228,7 @@ ecryptfs_create(struct inode *directory_inode, struct dentry *ecryptfs_dentry,
 {
         int rc;
 
-        /* ecryptfs_do_create() calls ecryptfs_interpose(), which opens
-         * the crypt_stat->lower_file (persistent file) */
+        /* ecryptfs_do_create() calls ecryptfs_interpose() */
         rc = ecryptfs_do_create(directory_inode, ecryptfs_dentry, mode, nd);
         if (unlikely(rc)) {
                 ecryptfs_printk(KERN_WARNING, "Failed to create file in"
@@ -244,141 +243,91 @@ out:
 }
 
 /**
- * ecryptfs_lookup
- * @dir: inode
- * @dentry: The dentry
- * @nd: nameidata, may be NULL
- *
- * Find a file on disk. If the file does not exist, then we'll add it to the
- * dentry cache and continue on to read it from the disk.
+ * ecryptfs_lookup_and_interpose_lower - Perform a lookup
  */
-static struct dentry *ecryptfs_lookup(struct inode *dir, struct dentry *dentry,
-                                      struct nameidata *nd)
+int ecryptfs_lookup_and_interpose_lower(struct dentry *ecryptfs_dentry,
+                                        struct dentry *lower_dentry,
+                                        struct ecryptfs_crypt_stat *crypt_stat,
+                                        struct inode *ecryptfs_dir_inode,
+                                        struct nameidata *ecryptfs_nd)
 {
-        int rc = 0;
         struct dentry *lower_dir_dentry;
-        struct dentry *lower_dentry;
         struct vfsmount *lower_mnt;
-        char *encoded_name;
-        int encoded_namelen;
-        struct ecryptfs_crypt_stat *crypt_stat = NULL;
+        struct inode *lower_inode;
         struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
         char *page_virt = NULL;
-        struct inode *lower_inode;
         u64 file_size;
+        int rc = 0;
 
-        lower_dir_dentry = ecryptfs_dentry_to_lower(dentry->d_parent);
-        dentry->d_op = &ecryptfs_dops;
-        if ((dentry->d_name.len == 1 && !strcmp(dentry->d_name.name, "."))
-            || (dentry->d_name.len == 2
-                && !strcmp(dentry->d_name.name, ".."))) {
-                d_drop(dentry);
-                goto out;
-        }
-        encoded_namelen = ecryptfs_encode_filename(crypt_stat,
-                                                   dentry->d_name.name,
-                                                   dentry->d_name.len,
-                                                   &encoded_name);
-        if (encoded_namelen < 0) {
-                rc = encoded_namelen;
-                d_drop(dentry);
-                goto out;
-        }
-        ecryptfs_printk(KERN_DEBUG, "encoded_name = [%s]; encoded_namelen "
-                        "= [%d]\n", encoded_name, encoded_namelen);
-        lower_dentry = lookup_one_len(encoded_name, lower_dir_dentry,
-                                      encoded_namelen - 1);
-        kfree(encoded_name);
-        if (IS_ERR(lower_dentry)) {
-                ecryptfs_printk(KERN_ERR, "ERR from lower_dentry\n");
-                rc = PTR_ERR(lower_dentry);
-                d_drop(dentry);
-                goto out;
-        }
-        lower_mnt = mntget(ecryptfs_dentry_to_lower_mnt(dentry->d_parent));
-        ecryptfs_printk(KERN_DEBUG, "lower_dentry = [%p]; lower_dentry->"
-                "d_name.name = [%s]\n", lower_dentry,
-                lower_dentry->d_name.name);
+        lower_dir_dentry = lower_dentry->d_parent;
+        lower_mnt = mntget(ecryptfs_dentry_to_lower_mnt(
+                                   ecryptfs_dentry->d_parent));
         lower_inode = lower_dentry->d_inode;
-        fsstack_copy_attr_atime(dir, lower_dir_dentry->d_inode);
+        fsstack_copy_attr_atime(ecryptfs_dir_inode, lower_dir_dentry->d_inode);
         BUG_ON(!atomic_read(&lower_dentry->d_count));
-        ecryptfs_set_dentry_private(dentry,
+        ecryptfs_set_dentry_private(ecryptfs_dentry,
                                     kmem_cache_alloc(ecryptfs_dentry_info_cache,
                                                      GFP_KERNEL));
-        if (!ecryptfs_dentry_to_private(dentry)) {
+        if (!ecryptfs_dentry_to_private(ecryptfs_dentry)) {
                 rc = -ENOMEM;
-                ecryptfs_printk(KERN_ERR, "Out of memory whilst attempting "
-                                "to allocate ecryptfs_dentry_info struct\n");
+                printk(KERN_ERR "%s: Out of memory whilst attempting "
+                       "to allocate ecryptfs_dentry_info struct\n",
+                        __func__);
                 goto out_dput;
         }
-        ecryptfs_set_dentry_lower(dentry, lower_dentry);
-        ecryptfs_set_dentry_lower_mnt(dentry, lower_mnt);
+        ecryptfs_set_dentry_lower(ecryptfs_dentry, lower_dentry);
+        ecryptfs_set_dentry_lower_mnt(ecryptfs_dentry, lower_mnt);
         if (!lower_dentry->d_inode) {
                 /* We want to add because we couldn't find in lower */
-                d_add(dentry, NULL);
+                d_add(ecryptfs_dentry, NULL);
                 goto out;
         }
-        rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb,
-                                ECRYPTFS_INTERPOSE_FLAG_D_ADD);
+        rc = ecryptfs_interpose(lower_dentry, ecryptfs_dentry,
+                                ecryptfs_dir_inode->i_sb, 1);
         if (rc) {
-                ecryptfs_printk(KERN_ERR, "Error interposing\n");
+                printk(KERN_ERR "%s: Error interposing; rc = [%d]\n",
+                       __func__, rc);
                 goto out;
         }
-        if (S_ISDIR(lower_inode->i_mode)) {
-                ecryptfs_printk(KERN_DEBUG, "Is a directory; returning\n");
+        if (S_ISDIR(lower_inode->i_mode))
                 goto out;
-        }
-        if (S_ISLNK(lower_inode->i_mode)) {
-                ecryptfs_printk(KERN_DEBUG, "Is a symlink; returning\n");
+        if (S_ISLNK(lower_inode->i_mode))
                 goto out;
-        }
-        if (special_file(lower_inode->i_mode)) {
-                ecryptfs_printk(KERN_DEBUG, "Is a special file; returning\n");
+        if (special_file(lower_inode->i_mode))
                 goto out;
-        }
-        if (!nd) {
-                ecryptfs_printk(KERN_DEBUG, "We have a NULL nd, just leave"
-                                "as we *think* we are about to unlink\n");
+        if (!ecryptfs_nd)
                 goto out;
-        }
         /* Released in this function */
-        page_virt = kmem_cache_zalloc(ecryptfs_header_cache_2,
-                                      GFP_USER);
+        page_virt = kmem_cache_zalloc(ecryptfs_header_cache_2, GFP_USER);
         if (!page_virt) {
+                printk(KERN_ERR "%s: Cannot kmem_cache_zalloc() a page\n",
+                       __func__);
                 rc = -ENOMEM;
-                ecryptfs_printk(KERN_ERR,
-                                "Cannot ecryptfs_kmalloc a page\n");
                 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 (!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__,
-                               dentry->d_name.name, rc);
-                        goto out;
+                               ecryptfs_dentry->d_name.name, rc);
+                        goto out_free_kmem;
                 }
         }
         rc = ecryptfs_read_and_validate_header_region(page_virt,
-                                                      dentry->d_inode);
+                                                      ecryptfs_dentry->d_inode);
         if (rc) {
-                rc = ecryptfs_read_and_validate_xattr_region(page_virt, dentry);
+                rc = ecryptfs_read_and_validate_xattr_region(page_virt,
+                                                             ecryptfs_dentry);
                 if (rc) {
-                        printk(KERN_DEBUG "Valid metadata not found in header "
-                               "region or xattr region; treating file as "
-                               "unencrypted\n");
                         rc = 0;
-                        kmem_cache_free(ecryptfs_header_cache_2, page_virt);
-                        goto out;
+                        goto out_free_kmem;
                 }
                 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
         }
         mount_crypt_stat = &ecryptfs_superblock_to_private(
-                dentry->d_sb)->mount_crypt_stat;
+                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->num_header_bytes_at_front
@@ -388,14 +337,103 @@ static struct dentry *ecryptfs_lookup(struct inode *dir, struct dentry *dentry,
         } else {
                 file_size = get_unaligned_be64(page_virt);
         }
-        i_size_write(dentry->d_inode, (loff_t)file_size);
+        i_size_write(ecryptfs_dentry->d_inode, (loff_t)file_size);
+out_free_kmem:
         kmem_cache_free(ecryptfs_header_cache_2, page_virt);
         goto out;
-
 out_dput:
         dput(lower_dentry);
-        d_drop(dentry);
+        d_drop(ecryptfs_dentry);
 out:
+        return rc;
+}
+
+/**
+ * ecryptfs_lookup
+ * @ecryptfs_dir_inode: The eCryptfs directory inode
+ * @ecryptfs_dentry: The eCryptfs dentry that we are looking up
+ * @ecryptfs_nd: nameidata; may be NULL
+ *
+ * Find a file on disk. If the file does not exist, then we'll add it to the
+ * dentry cache and continue on to read it from the disk.
+ */
+static struct dentry *ecryptfs_lookup(struct inode *ecryptfs_dir_inode,
+                                      struct dentry *ecryptfs_dentry,
+                                      struct nameidata *ecryptfs_nd)
+{
+        char *encrypted_and_encoded_name = NULL;
+        int encrypted_and_encoded_name_size;
+        struct ecryptfs_crypt_stat *crypt_stat = NULL;
+        struct ecryptfs_mount_crypt_stat *mount_crypt_stat = NULL;
+        struct ecryptfs_inode_info *inode_info;
+        struct dentry *lower_dir_dentry, *lower_dentry;
+        int rc = 0;
+
+        ecryptfs_dentry->d_op = &ecryptfs_dops;
+        if ((ecryptfs_dentry->d_name.len == 1
+             && !strcmp(ecryptfs_dentry->d_name.name, "."))
+            || (ecryptfs_dentry->d_name.len == 2
+                && !strcmp(ecryptfs_dentry->d_name.name, ".."))) {
+                goto out_d_drop;
+        }
+        lower_dir_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry->d_parent);
+        lower_dentry = lookup_one_len(ecryptfs_dentry->d_name.name,
+                                      lower_dir_dentry,
+                                      ecryptfs_dentry->d_name.len);
+        if (IS_ERR(lower_dentry)) {
+                rc = PTR_ERR(lower_dentry);
+                printk(KERN_ERR "%s: lookup_one_len() returned [%d] on "
+                       "lower_dentry = [%s]\n", __func__, rc,
+                       ecryptfs_dentry->d_name.name);
+                goto out_d_drop;
+        }
+        if (lower_dentry->d_inode)
+                goto lookup_and_interpose;
+        inode_info =  ecryptfs_inode_to_private(ecryptfs_dentry->d_inode);
+        if (inode_info) {
+                crypt_stat = &inode_info->crypt_stat;
+                /* TODO: lock for crypt_stat comparison */
+                if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED))
+                        ecryptfs_set_default_sizes(crypt_stat);
+        }
+        if (crypt_stat)
+                mount_crypt_stat = crypt_stat->mount_crypt_stat;
+        else
+                mount_crypt_stat = &ecryptfs_superblock_to_private(
+                        ecryptfs_dentry->d_sb)->mount_crypt_stat;
+        if (!(crypt_stat && (crypt_stat->flags & ECRYPTFS_ENCRYPT_FILENAMES))
+            && !(mount_crypt_stat && (mount_crypt_stat->flags
+                                     & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)))
+                goto lookup_and_interpose;
+        dput(lower_dentry);
+        rc = ecryptfs_encrypt_and_encode_filename(
+                &encrypted_and_encoded_name, &encrypted_and_encoded_name_size,
+                crypt_stat, mount_crypt_stat, ecryptfs_dentry->d_name.name,
+                ecryptfs_dentry->d_name.len);
+        if (rc) {
+                printk(KERN_ERR "%s: Error attempting to encrypt and encode "
+                       "filename; rc = [%d]\n", __func__, rc);
+                goto out_d_drop;
+        }
+        lower_dentry = lookup_one_len(encrypted_and_encoded_name,
+                                      lower_dir_dentry,
+                                      encrypted_and_encoded_name_size - 1);
+        if (IS_ERR(lower_dentry)) {
+                rc = PTR_ERR(lower_dentry);
+                printk(KERN_ERR "%s: lookup_one_len() returned [%d] on "
+                       "lower_dentry = [%s]\n", __func__, rc,
+                       encrypted_and_encoded_name);
+                goto out_d_drop;
+        }
+lookup_and_interpose:
+        rc = ecryptfs_lookup_and_interpose_lower(ecryptfs_dentry, lower_dentry,
+                                                 crypt_stat, ecryptfs_dir_inode,
+                                                 ecryptfs_nd);
+        goto out;
+out_d_drop:
+        d_drop(ecryptfs_dentry);
+out:
+        kfree(encrypted_and_encoded_name);
         return ERR_PTR(rc);
 }
 
@@ -466,19 +504,21 @@ static int ecryptfs_symlink(struct inode *dir, struct dentry *dentry,
         struct dentry *lower_dentry;
         struct dentry *lower_dir_dentry;
         char *encoded_symname;
-        int encoded_symlen;
-        struct ecryptfs_crypt_stat *crypt_stat = NULL;
+        size_t encoded_symlen;
+        struct ecryptfs_mount_crypt_stat *mount_crypt_stat = NULL;
 
         lower_dentry = ecryptfs_dentry_to_lower(dentry);
         dget(lower_dentry);
         lower_dir_dentry = lock_parent(lower_dentry);
-        encoded_symlen = ecryptfs_encode_filename(crypt_stat, symname,
-                                                  strlen(symname),
-                                                  &encoded_symname);
-        if (encoded_symlen < 0) {
-                rc = encoded_symlen;
+        mount_crypt_stat = &ecryptfs_superblock_to_private(
+                dir->i_sb)->mount_crypt_stat;
+        rc = ecryptfs_encrypt_and_encode_filename(&encoded_symname,
+                                                  &encoded_symlen,
+                                                  NULL,
+                                                  mount_crypt_stat, symname,
+                                                  strlen(symname));
+        if (rc)
                 goto out_lock;
-        }
         rc = vfs_symlink(lower_dir_dentry->d_inode, lower_dentry,
                          encoded_symname);
         kfree(encoded_symname);
@@ -602,52 +642,54 @@ out_lock:
 }
 
 static int
-ecryptfs_readlink(struct dentry *dentry, char __user * buf, int bufsiz)
+ecryptfs_readlink(struct dentry *dentry, char __user *buf, int bufsiz)
 {
-        int rc;
-        struct dentry *lower_dentry;
-        char *decoded_name;
         char *lower_buf;
-        mm_segment_t old_fs;
+        struct dentry *lower_dentry;
         struct ecryptfs_crypt_stat *crypt_stat;
+        char *plaintext_name;
+        size_t plaintext_name_size;
+        mm_segment_t old_fs;
+        int rc;
 
         lower_dentry = ecryptfs_dentry_to_lower(dentry);
         if (!lower_dentry->d_inode->i_op->readlink) {
                 rc = -EINVAL;
                 goto out;
         }
+        crypt_stat = &ecryptfs_inode_to_private(dentry->d_inode)->crypt_stat;
         /* Released in this function */
         lower_buf = kmalloc(bufsiz, GFP_KERNEL);
         if (lower_buf == NULL) {
-                ecryptfs_printk(KERN_ERR, "Out of memory\n");
+                printk(KERN_ERR "%s: Out of memory whilst attempting to "
+                       "kmalloc [%d] bytes\n", __func__, bufsiz);
                 rc = -ENOMEM;
                 goto out;
         }
         old_fs = get_fs();
         set_fs(get_ds());
-        ecryptfs_printk(KERN_DEBUG, "Calling readlink w/ "
-                        "lower_dentry->d_name.name = [%s]\n",
-                        lower_dentry->d_name.name);
         rc = lower_dentry->d_inode->i_op->readlink(lower_dentry,
                                                    (char __user *)lower_buf,
                                                    bufsiz);
         set_fs(old_fs);
         if (rc >= 0) {
-                crypt_stat = NULL;
-                rc = ecryptfs_decode_filename(crypt_stat, lower_buf, rc,
-                                              &decoded_name);
-                if (rc == -ENOMEM)
+                rc = ecryptfs_decode_and_decrypt_filename(&plaintext_name,
+                                                          &plaintext_name_size,
+                                                          dentry, lower_buf,
+                                                          rc);
+                if (rc) {
+                        printk(KERN_ERR "%s: Error attempting to decode and "
+                               "decrypt filename; rc = [%d]\n", __func__,
+                                rc);
                         goto out_free_lower_buf;
-                if (rc > 0) {
-                        ecryptfs_printk(KERN_DEBUG, "Copying [%d] bytes "
-                                        "to userspace: [%*s]\n", rc,
-                                        decoded_name);
-                        if (copy_to_user(buf, decoded_name, rc))
-                                rc = -EFAULT;
                 }
-                kfree(decoded_name);
-                fsstack_copy_attr_atime(dentry->d_inode,
-                                        lower_dentry->d_inode);
+                rc = copy_to_user(buf, plaintext_name, plaintext_name_size);
+                if (rc)
+                        rc = -EFAULT;
+                else
+                        rc = plaintext_name_size;
+                kfree(plaintext_name);
+                fsstack_copy_attr_atime(dentry->d_inode, lower_dentry->d_inode);
         }
 out_free_lower_buf:
         kfree(lower_buf);
@@ -669,8 +711,6 @@ static void *ecryptfs_follow_link(struct dentry *dentry, struct nameidata *nd)
         }
         old_fs = get_fs();
         set_fs(get_ds());
-        ecryptfs_printk(KERN_DEBUG, "Calling readlink w/ "
-                        "dentry->d_name.name = [%s]\n", dentry->d_name.name);
         rc = dentry->d_inode->i_op->readlink(dentry, (char __user *)buf, len);
         set_fs(old_fs);
         if (rc < 0)