ubifs: Implement UBIFS_FLG_ENCRYPTION

This feature flag indicates that the filesystem contains encrypted
files.

Signed-off-by: Richard Weinberger <richard@nod.at>

4 files changed, 50 insertions, 0 deletions

diff --git a/fs/ubifs/ioctl.c b/fs/ubifs/ioctl.c
index 6bb5b35050de..3d10f5525274 100644
--- a/fs/ubifs/ioctl.c
+++ b/fs/ubifs/ioctl.c
@@ -183,6 +183,7 @@ long ubifs_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
         }
         case FS_IOC_SET_ENCRYPTION_POLICY: {
 #ifdef CONFIG_UBIFS_FS_ENCRYPTION
+                struct ubifs_info *c = inode->i_sb->s_fs_info;
                 struct fscrypt_policy policy;
 
                 if (copy_from_user(&policy,
@@ -190,6 +191,10 @@ long ubifs_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
                                    sizeof(policy)))
                         return -EFAULT;
 
+                err = ubifs_enable_encryption(c);
+                if (err)
+                        return err;
+
                 err = fscrypt_process_policy(file, &policy);
 
                 return err;
diff --git a/fs/ubifs/sb.c b/fs/ubifs/sb.c
index 4a2b4c361587..54cef70ea16f 100644
--- a/fs/ubifs/sb.c
+++ b/fs/ubifs/sb.c
@@ -622,6 +622,16 @@ int ubifs_read_superblock(struct ubifs_info *c)
         c->big_lpt = !!(sup_flags & UBIFS_FLG_BIGLPT);
         c->space_fixup = !!(sup_flags & UBIFS_FLG_SPACE_FIXUP);
         c->double_hash = !!(sup_flags & UBIFS_FLG_DOUBLE_HASH);
+        c->encrypted = !!(sup_flags & UBIFS_FLG_ENCRYPTION);
+
+#ifndef CONFIG_UBIFS_FS_ENCRYPTION
+        if (c->encrypted) {
+                ubifs_err(c, "file system contains encrypted files but UBIFS"
+                             " was built without crypto support.");
+                err = -EINVAL;
+                goto out;
+        }
+#endif
 
         /* Automatically increase file system size to the maximum size */
         c->old_leb_cnt = c->leb_cnt;
@@ -809,3 +819,33 @@ int ubifs_fixup_free_space(struct ubifs_info *c)
         ubifs_msg(c, "free space fixup complete");
         return err;
 }
+
+int ubifs_enable_encryption(struct ubifs_info *c)
+{
+        int err;
+        struct ubifs_sb_node *sup;
+
+        if (c->encrypted)
+                return 0;
+
+        if (c->ro_mount || c->ro_media)
+                return -EROFS;
+
+        if (c->fmt_version < 5) {
+                ubifs_err(c, "on-flash format version 5 is needed for encryption");
+                return -EINVAL;
+        }
+
+        sup = ubifs_read_sb_node(c);
+        if (IS_ERR(sup))
+                return PTR_ERR(sup);
+
+        sup->flags |= cpu_to_le32(UBIFS_FLG_ENCRYPTION);
+
+        err = ubifs_write_sb_node(c, sup);
+        if (!err)
+                c->encrypted = 1;
+        kfree(sup);
+
+        return err;
+}
diff --git a/fs/ubifs/ubifs-media.h b/fs/ubifs/ubifs-media.h
index 0cbdc6b70a00..bdc7935a5e41 100644
--- a/fs/ubifs/ubifs-media.h
+++ b/fs/ubifs/ubifs-media.h
@@ -420,11 +420,13 @@ enum {
  * UBIFS_FLG_SPACE_FIXUP: first-mount "fixup" of free space within LEBs needed
  * UBIFS_FLG_DOUBLE_HASH: store a 32bit cookie in directory entry nodes to
  *                        support 64bit cookies for lookups by hash
+ * UBIFS_FLG_ENCRYPTION: this filesystem contains encrypted files
  */
 enum {
         UBIFS_FLG_BIGLPT = 0x02,
         UBIFS_FLG_SPACE_FIXUP = 0x04,
         UBIFS_FLG_DOUBLE_HASH = 0x08,
+        UBIFS_FLG_ENCRYPTION = 0x10,
 };
 
 /**
diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h
index 5089663c0d1b..8d0e4818e3ea 100644
--- a/fs/ubifs/ubifs.h
+++ b/fs/ubifs/ubifs.h
@@ -1007,6 +1007,7 @@ struct ubifs_debug_info;
  * @big_lpt: flag that LPT is too big to write whole during commit
  * @space_fixup: flag indicating that free space in LEBs needs to be cleaned up
  * @double_hash: flag indicating that we can do lookups by hash
+ * @encrypted: flag indicating that this file system contains encrypted files
  * @no_chk_data_crc: do not check CRCs when reading data nodes (except during
  *                   recovery)
  * @bulk_read: enable bulk-reads
@@ -1250,6 +1251,7 @@ struct ubifs_info {
         unsigned int big_lpt:1;
         unsigned int space_fixup:1;
         unsigned int double_hash:1;
+        unsigned int encrypted:1;
         unsigned int no_chk_data_crc:1;
         unsigned int bulk_read:1;
         unsigned int default_compr:2;
@@ -1649,6 +1651,7 @@ int ubifs_read_superblock(struct ubifs_info *c);
 struct ubifs_sb_node *ubifs_read_sb_node(struct ubifs_info *c);
 int ubifs_write_sb_node(struct ubifs_info *c, struct ubifs_sb_node *sup);
 int ubifs_fixup_free_space(struct ubifs_info *c);
+int ubifs_enable_encryption(struct ubifs_info *c);
 
 /* replay.c */
 int ubifs_validate_entry(struct ubifs_info *c,