Commit 3f093ccb authored by Daniel Vacek's avatar Daniel Vacek Committed by David Sterba
Browse files

btrfs: harden parsing of compression mount options 



Btrfs happily but incorrectly accepts the `-o compress=zlib+foo` and similar
options with any random suffix.

Fix that by explicitly checking the end of the strings.

Signed-off-by: default avatarDaniel Vacek <neelx@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 3f0e865a

fs/btrfs/super.c

+18 −7
Original line number Diff line number Diff line
@@ -267,9 +267,19 @@ static inline blk_mode_t btrfs_open_mode(struct fs_context *fc) 
	return sb_open_mode(fc->sb_flags) & ~BLK_OPEN_RESTRICT_WRITES;

}



static bool btrfs_match_compress_type(const char *string, const char *type, bool may_have_level)

{

	const int len = strlen(type);



	return (strncmp(string, type, len) == 0) &&

		((may_have_level && string[len] == ':') || string[len] == '\0');

}



static int btrfs_parse_compress(struct btrfs_fs_context *ctx,

				const struct fs_parameter *param, int opt)

{

	const char *string = param->string;



	/*

	 * Provide the same semantics as older kernels that don't use fs

	 * context, specifying the "compress" option clears "force-compress"
@@ -285,33 +295,34 @@ static int btrfs_parse_compress(struct btrfs_fs_context *ctx, 
		btrfs_set_opt(ctx->mount_opt, COMPRESS);

		btrfs_clear_opt(ctx->mount_opt, NODATACOW);

		btrfs_clear_opt(ctx->mount_opt, NODATASUM);

	} else if (strncmp(param->string, "zlib", 4) == 0) {

	} else if (btrfs_match_compress_type(string, "zlib", true)) {

		ctx->compress_type = BTRFS_COMPRESS_ZLIB;

		ctx->compress_level = btrfs_compress_str2level(BTRFS_COMPRESS_ZLIB,

							       param->string + 4);

							       string + 4);

		btrfs_set_opt(ctx->mount_opt, COMPRESS);

		btrfs_clear_opt(ctx->mount_opt, NODATACOW);

		btrfs_clear_opt(ctx->mount_opt, NODATASUM);

	} else if (strncmp(param->string, "lzo", 3) == 0) {

	} else if (btrfs_match_compress_type(string, "lzo", false)) {

		ctx->compress_type = BTRFS_COMPRESS_LZO;

		ctx->compress_level = 0;

		btrfs_set_opt(ctx->mount_opt, COMPRESS);

		btrfs_clear_opt(ctx->mount_opt, NODATACOW);

		btrfs_clear_opt(ctx->mount_opt, NODATASUM);

	} else if (strncmp(param->string, "zstd", 4) == 0) {

	} else if (btrfs_match_compress_type(string, "zstd", true)) {

		ctx->compress_type = BTRFS_COMPRESS_ZSTD;

		ctx->compress_level = btrfs_compress_str2level(BTRFS_COMPRESS_ZSTD,

							       param->string + 4);

							       string + 4);

		btrfs_set_opt(ctx->mount_opt, COMPRESS);

		btrfs_clear_opt(ctx->mount_opt, NODATACOW);

		btrfs_clear_opt(ctx->mount_opt, NODATASUM);

	} else if (strncmp(param->string, "no", 2) == 0) {

	} else if (btrfs_match_compress_type(string, "no", false) ||

		   btrfs_match_compress_type(string, "none", false)) {

		ctx->compress_level = 0;

		ctx->compress_type = 0;

		btrfs_clear_opt(ctx->mount_opt, COMPRESS);

		btrfs_clear_opt(ctx->mount_opt, FORCE_COMPRESS);

	} else {

		btrfs_err(NULL, "unrecognized compression value %s", param->string);

		btrfs_err(NULL, "unrecognized compression value %s", string);

		return -EINVAL;

	}

	return 0;