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Commit efee590e authored by Eric Biggers's avatar Eric Biggers Committed by Theodore Ts'o
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fscrypt: pass up error codes from ->get_context() 



It was possible for the ->get_context() operation to fail with a
specific error code, which was then not returned to the caller of
FS_IOC_SET_ENCRYPTION_POLICY or FS_IOC_GET_ENCRYPTION_POLICY.  Make sure
to pass through these error codes.  Also reorganize the code so that
->get_context() only needs to be called one time when setting an
encryption policy, and handle contexts of unrecognized sizes more
appropriately.

Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent 868e1bc6

fs/crypto/policy.c

+23 −31
Original line number Diff line number Diff line
@@ -13,37 +13,20 @@ 
#include <linux/mount.h>

#include "fscrypt_private.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);

}



/*

 * 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,

	return memcmp(ctx->master_key_descriptor, policy->master_key_descriptor,

		      FS_KEY_DESCRIPTOR_SIZE) == 0 &&

			(ctx.flags == policy->flags) &&

			(ctx.contents_encryption_mode ==

		(ctx->flags == policy->flags) &&

		(ctx->contents_encryption_mode ==

		 policy->contents_encryption_mode) &&

			(ctx.filenames_encryption_mode ==

			 policy->filenames_encryption_mode));

		(ctx->filenames_encryption_mode ==

		 policy->filenames_encryption_mode);

}



static int create_encryption_context_from_policy(struct inode *inode,
@@ -90,6 +73,7 @@ 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;
@@ -106,7 +90,8 @@ int fscrypt_ioctl_set_policy(struct file *filp, const void __user *arg) 


	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 = -ENOTDIR;

		else if (!inode->i_sb->s_cop->empty_dir)
@@ -116,8 +101,13 @@ int fscrypt_ioctl_set_policy(struct file *filp, const void __user *arg) 
		else

			ret = create_encryption_context_from_policy(inode,

								    &policy);

	} else if (!is_encryption_context_consistent_with_policy(inode,

	} 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;

	}
@@ -140,8 +130,10 @@ int fscrypt_ioctl_get_policy(struct file *filp, void __user *arg) 
		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;