f2fs/fscrypt: catch up to v4.12

Applied f2fs-related patches only, and tried to exclude other layers' changes.

- fs/f2fs

c6b1e36c8fa0 Merge branch 'for-4.13/block' of git://git.kernel.dk/linux-block
81e3e044897b Merge tag 'uuid-for-4.13' of git://git.infradead.org/users/hch/uuid
fdd050b5b3c9 Merge branch 'uuid-types' of bombadil.infradead.org:public_git/uuid into nvme-base
4e4cbee93d56 block: switch bios to blk_status_t
d41519a69b35 crypto: Work around deallocated stack frame reference gcc bug on sparc.
85787090a21e fs: switch ->s_uuid to uuid_t
bf5f89463f5b Merge branch 'akpm' (patches from Andrew)
48fbfe50f1d5 fs: f2fs: use ktime_get_real_seconds for sit_info times
a7c3e901a46f mm: introduce kv[mz]alloc helpers
70ef8f0d3757 Merge tag 'for-f2fs-4.12' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs
...

- fs/crypto/

4e4cbee93d56 block: switch bios to blk_status_t
17159420a6c1 fscrypt: introduce helper function for filename matching
6b06cdee81d6 fscrypt: avoid collisions when presenting long encrypted filenames
272f98f68462 fscrypt: fix context consistency check when key(s) unavailable
9c8268def612 fscrypt: Move key structure and constants to uapi
cd39e4bac111 fscrypt: remove unnecessary checks for NULL operations
a643f9054c21 Merge tag 'fscrypt-for-linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/fscrypt
...

- fs/ext4/
: Applied fscrypt-related changes only.

Signed-off-by: Jaegeuk Kim <jaegeuk@google.com>
diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c
index bb4e209..210976e 100644
--- a/fs/crypto/policy.c
+++ b/fs/crypto/policy.c
@@ -10,76 +10,41 @@
 
 #include <linux/random.h>
 #include <linux/string.h>
-#include <linux/fscrypto.h>
 #include <linux/mount.h>
-
-static int inode_has_encryption_context(struct inode *inode)
-{
-	if (!inode->i_sb->s_cop->get_context)
-		return 0;
-	return (inode->i_sb->s_cop->get_context(inode, NULL, 0L) > 0);
-}
+#include "fscrypt_private.h"
 
 /*
- * check whether the policy is consistent with the encryption context
- * for the inode
+ * check whether an encryption policy is consistent with an encryption context
  */
-static int is_encryption_context_consistent_with_policy(struct inode *inode,
+static bool is_encryption_context_consistent_with_policy(
+				const struct fscrypt_context *ctx,
 				const struct fscrypt_policy *policy)
 {
-	struct fscrypt_context ctx;
-	int res;
-
-	if (!inode->i_sb->s_cop->get_context)
-		return 0;
-
-	res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx));
-	if (res != sizeof(ctx))
-		return 0;
-
-	return (memcmp(ctx.master_key_descriptor, policy->master_key_descriptor,
-			FS_KEY_DESCRIPTOR_SIZE) == 0 &&
-			(ctx.flags == policy->flags) &&
-			(ctx.contents_encryption_mode ==
-			 policy->contents_encryption_mode) &&
-			(ctx.filenames_encryption_mode ==
-			 policy->filenames_encryption_mode));
+	return memcmp(ctx->master_key_descriptor, policy->master_key_descriptor,
+		      FS_KEY_DESCRIPTOR_SIZE) == 0 &&
+		(ctx->flags == policy->flags) &&
+		(ctx->contents_encryption_mode ==
+		 policy->contents_encryption_mode) &&
+		(ctx->filenames_encryption_mode ==
+		 policy->filenames_encryption_mode);
 }
 
 static int create_encryption_context_from_policy(struct inode *inode,
 				const struct fscrypt_policy *policy)
 {
 	struct fscrypt_context ctx;
-	int res;
-
-	if (!inode->i_sb->s_cop->set_context)
-		return -EOPNOTSUPP;
-
-	if (inode->i_sb->s_cop->prepare_context) {
-		res = inode->i_sb->s_cop->prepare_context(inode);
-		if (res)
-			return res;
-	}
 
 	ctx.format = FS_ENCRYPTION_CONTEXT_FORMAT_V1;
 	memcpy(ctx.master_key_descriptor, policy->master_key_descriptor,
 					FS_KEY_DESCRIPTOR_SIZE);
 
 	if (!fscrypt_valid_contents_enc_mode(
-				policy->contents_encryption_mode)) {
-		printk(KERN_WARNING
-		       "%s: Invalid contents encryption mode %d\n", __func__,
-			policy->contents_encryption_mode);
+				policy->contents_encryption_mode))
 		return -EINVAL;
-	}
 
 	if (!fscrypt_valid_filenames_enc_mode(
-				policy->filenames_encryption_mode)) {
-		printk(KERN_WARNING
-			"%s: Invalid filenames encryption mode %d\n", __func__,
-			policy->filenames_encryption_mode);
+				policy->filenames_encryption_mode))
 		return -EINVAL;
-	}
 
 	if (policy->flags & ~FS_POLICY_FLAGS_VALID)
 		return -EINVAL;
@@ -93,16 +58,20 @@
 	return inode->i_sb->s_cop->set_context(inode, &ctx, sizeof(ctx), NULL);
 }
 
-int fscrypt_process_policy(struct file *filp,
-				const struct fscrypt_policy *policy)
+int fscrypt_ioctl_set_policy(struct file *filp, const void __user *arg)
 {
+	struct fscrypt_policy policy;
 	struct inode *inode = file_inode(filp);
 	int ret;
+	struct fscrypt_context ctx;
+
+	if (copy_from_user(&policy, arg, sizeof(policy)))
+		return -EFAULT;
 
 	if (!inode_owner_or_capable(inode))
 		return -EACCES;
 
-	if (policy->version != 0)
+	if (policy.version != 0)
 		return -EINVAL;
 
 	ret = mnt_want_write_file(filp);
@@ -111,22 +80,23 @@
 
 	inode_lock(inode);
 
-	if (!inode_has_encryption_context(inode)) {
+	ret = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx));
+	if (ret == -ENODATA) {
 		if (!S_ISDIR(inode->i_mode))
-			ret = -EINVAL;
-		else if (!inode->i_sb->s_cop->empty_dir)
-			ret = -EOPNOTSUPP;
+			ret = -ENOTDIR;
 		else if (!inode->i_sb->s_cop->empty_dir(inode))
 			ret = -ENOTEMPTY;
 		else
 			ret = create_encryption_context_from_policy(inode,
-								    policy);
-	} else if (!is_encryption_context_consistent_with_policy(inode,
-								 policy)) {
-		printk(KERN_WARNING
-		       "%s: Policy inconsistent with encryption context\n",
-		       __func__);
-		ret = -EINVAL;
+								    &policy);
+	} else if (ret == sizeof(ctx) &&
+		   is_encryption_context_consistent_with_policy(&ctx,
+								&policy)) {
+		/* The file already uses the same encryption policy. */
+		ret = 0;
+	} else if (ret >= 0 || ret == -ERANGE) {
+		/* The file already uses a different encryption policy. */
+		ret = -EEXIST;
 	}
 
 	inode_unlock(inode);
@@ -134,32 +104,38 @@
 	mnt_drop_write_file(filp);
 	return ret;
 }
-EXPORT_SYMBOL(fscrypt_process_policy);
+EXPORT_SYMBOL(fscrypt_ioctl_set_policy);
 
-int fscrypt_get_policy(struct inode *inode, struct fscrypt_policy *policy)
+int fscrypt_ioctl_get_policy(struct file *filp, void __user *arg)
 {
+	struct inode *inode = file_inode(filp);
 	struct fscrypt_context ctx;
+	struct fscrypt_policy policy;
 	int res;
 
-	if (!inode->i_sb->s_cop->get_context ||
-			!inode->i_sb->s_cop->is_encrypted(inode))
+	if (!inode->i_sb->s_cop->is_encrypted(inode))
 		return -ENODATA;
 
 	res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx));
+	if (res < 0 && res != -ERANGE)
+		return res;
 	if (res != sizeof(ctx))
-		return -ENODATA;
+		return -EINVAL;
 	if (ctx.format != FS_ENCRYPTION_CONTEXT_FORMAT_V1)
 		return -EINVAL;
 
-	policy->version = 0;
-	policy->contents_encryption_mode = ctx.contents_encryption_mode;
-	policy->filenames_encryption_mode = ctx.filenames_encryption_mode;
-	policy->flags = ctx.flags;
-	memcpy(&policy->master_key_descriptor, ctx.master_key_descriptor,
+	policy.version = 0;
+	policy.contents_encryption_mode = ctx.contents_encryption_mode;
+	policy.filenames_encryption_mode = ctx.filenames_encryption_mode;
+	policy.flags = ctx.flags;
+	memcpy(policy.master_key_descriptor, ctx.master_key_descriptor,
 				FS_KEY_DESCRIPTOR_SIZE);
+
+	if (copy_to_user(arg, &policy, sizeof(policy)))
+		return -EFAULT;
 	return 0;
 }
-EXPORT_SYMBOL(fscrypt_get_policy);
+EXPORT_SYMBOL(fscrypt_ioctl_get_policy);
 
 /**
  * fscrypt_has_permitted_context() - is a file's encryption policy permitted
@@ -258,9 +234,9 @@
  * @parent: Parent inode from which the context is inherited.
  * @child:  Child inode that inherits the context from @parent.
  * @fs_data:  private data given by FS.
- * @preload:  preload child i_crypt_info
+ * @preload:  preload child i_crypt_info if true
  *
- * Return: Zero on success, non-zero otherwise
+ * Return: 0 on success, -errno on failure
  */
 int fscrypt_inherit_context(struct inode *parent, struct inode *child,
 						void *fs_data, bool preload)
@@ -269,9 +245,6 @@
 	struct fscrypt_info *ci;
 	int res;
 
-	if (!parent->i_sb->s_cop->set_context)
-		return -EOPNOTSUPP;
-
 	res = fscrypt_get_encryption_info(parent);
 	if (res < 0)
 		return res;
@@ -281,19 +254,11 @@
 		return -ENOKEY;
 
 	ctx.format = FS_ENCRYPTION_CONTEXT_FORMAT_V1;
-	if (fscrypt_dummy_context_enabled(parent)) {
-		ctx.contents_encryption_mode = FS_ENCRYPTION_MODE_AES_256_XTS;
-		ctx.filenames_encryption_mode = FS_ENCRYPTION_MODE_AES_256_CTS;
-		ctx.flags = 0;
-		memset(ctx.master_key_descriptor, 0x42, FS_KEY_DESCRIPTOR_SIZE);
-		res = 0;
-	} else {
-		ctx.contents_encryption_mode = ci->ci_data_mode;
-		ctx.filenames_encryption_mode = ci->ci_filename_mode;
-		ctx.flags = ci->ci_flags;
-		memcpy(ctx.master_key_descriptor, ci->ci_master_key,
-				FS_KEY_DESCRIPTOR_SIZE);
-	}
+	ctx.contents_encryption_mode = ci->ci_data_mode;
+	ctx.filenames_encryption_mode = ci->ci_filename_mode;
+	ctx.flags = ci->ci_flags;
+	memcpy(ctx.master_key_descriptor, ci->ci_master_key,
+	       FS_KEY_DESCRIPTOR_SIZE);
 	get_random_bytes(ctx.nonce, FS_KEY_DERIVATION_NONCE_SIZE);
 	res = parent->i_sb->s_cop->set_context(child, &ctx,
 						sizeof(ctx), fs_data);