Re: [f2fs-dev] [PATCH] f2fs-tools: support print_xattr_entry with fscrypt context v2

[Eric Biggers <ebiggers@kernel.org>]

Hi Weichao,

On Wed, Jul 12, 2023 at 06:23:31PM +0800, Weichao Guo via Linux-f2fs-devel wrote:
> Signed-off-by: Weichao Guo <guoweichao@oppo.com>
> Signed-off-by: Sheng Yong <shengyong@oppo.com>
> ---
>  fsck/mount.c | 44 +++++++++++++++++++++++++++---------------
>  fsck/xattr.h | 54 +++++++++++++++++++++++++++++++++++++++++++---------
>  2 files changed, 74 insertions(+), 24 deletions(-)
> 
> diff --git a/fsck/mount.c b/fsck/mount.c
> index 397feb5..b9696c4 100644
> --- a/fsck/mount.c
> +++ b/fsck/mount.c
> @@ -196,7 +196,7 @@ static void print_xattr_entry(const struct f2fs_xattr_entry *ent)
>  {
>  	const u8 *value = (const u8 *)&ent->e_name[ent->e_name_len];
>  	const int size = le16_to_cpu(ent->e_value_size);
> -	const struct fscrypt_context *ctx;
> +	const union fscrypt_context *ctx;
>  	int i;
>  
>  	MSG(0, "\nxattr: e_name_index:%d e_name:", ent->e_name_index);
> @@ -213,21 +213,35 @@ static void print_xattr_entry(const struct f2fs_xattr_entry *ent)
>  		return;
>  #endif
>  	case F2FS_XATTR_INDEX_ENCRYPTION:
> -		ctx = (const struct fscrypt_context *)value;
> -		if (size != sizeof(*ctx) ||
> -		    ctx->format != FS_ENCRYPTION_CONTEXT_FORMAT_V1)
> +		ctx = (const union fscrypt_context *)value;
> +		if (size != fscrypt_context_size(ctx))
>  			break;
> -		MSG(0, "format: %d\n", ctx->format);
> -		MSG(0, "contents_encryption_mode: 0x%x\n", ctx->contents_encryption_mode);
> -		MSG(0, "filenames_encryption_mode: 0x%x\n", ctx->filenames_encryption_mode);
> -		MSG(0, "flags: 0x%x\n", ctx->flags);
> -		MSG(0, "master_key_descriptor: ");
> -		for (i = 0; i < FS_KEY_DESCRIPTOR_SIZE; i++)
> -			MSG(0, "%02X", ctx->master_key_descriptor[i]);
> -		MSG(0, "\nnonce: ");
> -		for (i = 0; i < FS_KEY_DERIVATION_NONCE_SIZE; i++)
> -			MSG(0, "%02X", ctx->nonce[i]);
> -		MSG(0, "\n");
> +		switch (ctx->version) {
> +		case FSCRYPT_CONTEXT_V1:
> +			MSG(0, "format: %d\n", ctx->version);
> +			MSG(0, "contents_encryption_mode: 0x%x\n", ctx->v1.contents_encryption_mode);
> +			MSG(0, "filenames_encryption_mode: 0x%x\n", ctx->v1.filenames_encryption_mode);
> +			MSG(0, "flags: 0x%x\n", ctx->v1.flags);
> +			MSG(0, "master_key_descriptor: ");
> +			for (i = 0; i < FSCRYPT_KEY_DESCRIPTOR_SIZE; i++)
> +				MSG(0, "%02X", ctx->v1.master_key_descriptor[i]);
> +			MSG(0, "\nnonce: ");
> +			for (i = 0; i < FSCRYPT_FILE_NONCE_SIZE; i++)
> +				MSG(0, "%02X", ctx->v1.nonce[i]);
> +			MSG(0, "\n");
> +		case FSCRYPT_CONTEXT_V2:
> +			MSG(0, "format: %d\n", ctx->version);
> +			MSG(0, "contents_encryption_mode: 0x%x\n", ctx->v2.contents_encryption_mode);
> +			MSG(0, "filenames_encryption_mode: 0x%x\n", ctx->v2.filenames_encryption_mode);
> +			MSG(0, "flags: 0x%x\n", ctx->v2.flags);
> +			MSG(0, "master_key_identifier: ");
> +			for (i = 0; i < FSCRYPT_KEY_IDENTIFIER_SIZE; i++)
> +				MSG(0, "%02X", ctx->v2.master_key_identifier[i]);
> +			MSG(0, "\nnonce: ");
> +			for (i = 0; i < FSCRYPT_FILE_NONCE_SIZE; i++)
> +				MSG(0, "%02X", ctx->v2.nonce[i]);
> +			MSG(0, "\n");
> +		}
>  		return;

The FSCRYPT_CONTEXT_V1 case is falling through to FSCRYPT_CONTEXT_V2.  Also,
this patch makes the values of encryption xattrs with unknown versions no longer
be shown.  To fix this, there needs to be a return at end of each case (v1 and
v2), and the return after the switch statement needs to be a break.

- Eric


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