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[85.226.165.230]) by smtp.googlemail.com with ESMTPSA id p20-20020a2e9a94000000b00289bb528b8dsm725473lji.49.2023.01.13.07.35.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 13 Jan 2023 07:35:08 -0800 (PST) From: Alexander Larsson To: linux-fsdevel@vger.kernel.org Cc: linux-kernel@vger.kernel.org, gscrivan@redhat.com, Alexander Larsson Subject: [PATCH v2 2/6] composefs: Add on-disk layout Date: Fri, 13 Jan 2023 16:33:55 +0100 Message-Id: <819f49676080b05c1e87bff785849f0cc375d245.1673623253.git.alexl@redhat.com> X-Mailer: git-send-email 2.39.0 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org This commit adds the on-disk layout header file of composefs. Signed-off-by: Alexander Larsson Co-developed-by: Giuseppe Scrivano Signed-off-by: Giuseppe Scrivano --- fs/composefs/cfs.h | 203 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 203 insertions(+) create mode 100644 fs/composefs/cfs.h diff --git a/fs/composefs/cfs.h b/fs/composefs/cfs.h new file mode 100644 index 000000000000..658df728e366 --- /dev/null +++ b/fs/composefs/cfs.h @@ -0,0 +1,203 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * composefs + * + * Copyright (C) 2021 Giuseppe Scrivano + * Copyright (C) 2022 Alexander Larsson + * + * This file is released under the GPL. + */ + +#ifndef _CFS_H +#define _CFS_H + +#include +#include +#include +#include +#include + +#define CFS_VERSION 1 + +#define CFS_MAGIC 0xc078629aU + +#define CFS_MAX_DIR_CHUNK_SIZE 4096 +#define CFS_MAX_XATTRS_SIZE 4096 + +static inline int cfs_digest_from_payload(const char *payload, size_t payload_len, + u8 digest_out[SHA256_DIGEST_SIZE]) +{ + const char *p, *end; + u8 last_digit = 0; + int digit = 0; + size_t n_nibbles = 0; + + /* This handles payloads (i.e. path names) that are "essentially" a + * digest as the digest (if the DIGEST_FROM_PAYLOAD flag is set). The + * "essential" part means that we ignore hierarchical structure as well + * as any extension. So, for example "ef/deadbeef.file" would match the + * (too short) digest "efdeadbeef". + * + * This allows images to avoid storing both the digest and the pathname, + * yet work with pre-existing object store formats of various kinds. + */ + + end = payload + payload_len; + for (p = payload; p != end; p++) { + /* Skip subdir structure */ + if (*p == '/') + continue; + + /* Break at (and ignore) extension */ + if (*p == '.') + break; + + if (n_nibbles == SHA256_DIGEST_SIZE * 2) + return -EINVAL; /* Too long */ + + digit = hex_to_bin(*p); + if (digit == -1) + return -EINVAL; /* Not hex digit */ + + n_nibbles++; + if ((n_nibbles % 2) == 0) + digest_out[n_nibbles / 2 - 1] = (last_digit << 4) | digit; + last_digit = digit; + } + + if (n_nibbles != SHA256_DIGEST_SIZE * 2) + return -EINVAL; /* Too short */ + + return 0; +} + +struct cfs_vdata_s { + u64 off; + u32 len; +} __packed; + +struct cfs_header_s { + u8 version; + u8 unused1; + u16 unused2; + + u32 magic; + u64 data_offset; + u64 root_inode; + + u64 unused3[2]; +} __packed; + +enum cfs_inode_flags { + CFS_INODE_FLAGS_NONE = 0, + CFS_INODE_FLAGS_PAYLOAD = 1 << 0, + CFS_INODE_FLAGS_MODE = 1 << 1, + CFS_INODE_FLAGS_NLINK = 1 << 2, + CFS_INODE_FLAGS_UIDGID = 1 << 3, + CFS_INODE_FLAGS_RDEV = 1 << 4, + CFS_INODE_FLAGS_TIMES = 1 << 5, + CFS_INODE_FLAGS_TIMES_NSEC = 1 << 6, + CFS_INODE_FLAGS_LOW_SIZE = 1 << 7, /* Low 32bit of st_size */ + CFS_INODE_FLAGS_HIGH_SIZE = 1 << 8, /* High 32bit of st_size */ + CFS_INODE_FLAGS_XATTRS = 1 << 9, + CFS_INODE_FLAGS_DIGEST = 1 << 10, /* fs-verity sha256 digest */ + CFS_INODE_FLAGS_DIGEST_FROM_PAYLOAD = 1 << 11, /* Compute digest from payload */ +}; + +#define CFS_INODE_FLAG_CHECK(_flag, _name) \ + (((_flag) & (CFS_INODE_FLAGS_##_name)) != 0) +#define CFS_INODE_FLAG_CHECK_SIZE(_flag, _name, _size) \ + (CFS_INODE_FLAG_CHECK(_flag, _name) ? (_size) : 0) + +#define CFS_INODE_DEFAULT_MODE 0100644 +#define CFS_INODE_DEFAULT_NLINK 1 +#define CFS_INODE_DEFAULT_NLINK_DIR 2 +#define CFS_INODE_DEFAULT_UIDGID 0 +#define CFS_INODE_DEFAULT_RDEV 0 +#define CFS_INODE_DEFAULT_TIMES 0 + +struct cfs_inode_s { + u32 flags; + + /* Optional data: (selected by flags) */ + + /* This is the size of the type specific data that comes directly after + * the inode in the file. Of this type: + * + * directory: cfs_dir_s + * regular file: the backing filename + * symlink: the target link + * + * Canonically payload_length is 0 for empty dir/file/symlink. + */ + u32 payload_length; + + u32 st_mode; /* File type and mode. */ + u32 st_nlink; /* Number of hard links, only for regular files. */ + u32 st_uid; /* User ID of owner. */ + u32 st_gid; /* Group ID of owner. */ + u32 st_rdev; /* Device ID (if special file). */ + u64 st_size; /* Size of file, only used for regular files */ + + struct cfs_vdata_s xattrs; /* ref to variable data */ + + u8 digest[SHA256_DIGEST_SIZE]; /* fs-verity digest */ + + struct timespec64 st_mtim; /* Time of last modification. */ + struct timespec64 st_ctim; /* Time of last status change. */ +}; + +static inline u32 cfs_inode_encoded_size(u32 flags) +{ + return sizeof(u32) /* flags */ + + CFS_INODE_FLAG_CHECK_SIZE(flags, PAYLOAD, sizeof(u32)) + + CFS_INODE_FLAG_CHECK_SIZE(flags, MODE, sizeof(u32)) + + CFS_INODE_FLAG_CHECK_SIZE(flags, NLINK, sizeof(u32)) + + CFS_INODE_FLAG_CHECK_SIZE(flags, UIDGID, sizeof(u32) + sizeof(u32)) + + CFS_INODE_FLAG_CHECK_SIZE(flags, RDEV, sizeof(u32)) + + CFS_INODE_FLAG_CHECK_SIZE(flags, TIMES, sizeof(u64) * 2) + + CFS_INODE_FLAG_CHECK_SIZE(flags, TIMES_NSEC, sizeof(u32) * 2) + + CFS_INODE_FLAG_CHECK_SIZE(flags, LOW_SIZE, sizeof(u32)) + + CFS_INODE_FLAG_CHECK_SIZE(flags, HIGH_SIZE, sizeof(u32)) + + CFS_INODE_FLAG_CHECK_SIZE(flags, XATTRS, sizeof(u64) + sizeof(u32)) + + CFS_INODE_FLAG_CHECK_SIZE(flags, DIGEST, SHA256_DIGEST_SIZE); +} + +struct cfs_dentry_s { + /* Index of struct cfs_inode_s */ + u64 inode_index; + u8 d_type; + u8 name_len; + u16 name_offset; +} __packed; + +struct cfs_dir_chunk_s { + u16 n_dentries; + u16 chunk_size; + u64 chunk_offset; +} __packed; + +struct cfs_dir_s { + u32 n_chunks; + struct cfs_dir_chunk_s chunks[]; +} __packed; + +#define cfs_dir_size(_n_chunks) \ + (sizeof(struct cfs_dir_s) + (_n_chunks) * sizeof(struct cfs_dir_chunk_s)) + +/* xattr representation. */ +struct cfs_xattr_element_s { + u16 key_length; + u16 value_length; +} __packed; + +struct cfs_xattr_header_s { + u16 n_attr; + struct cfs_xattr_element_s attr[0]; +} __packed; + +#define cfs_xattr_header_size(_n_element) \ + (sizeof(struct cfs_xattr_header_s) + \ + (_n_element) * sizeof(struct cfs_xattr_element_s)) + +#endif