fs/ecryptfs/crypto.c

Source file repositories/reference/linux-study-clean/fs/ecryptfs/crypto.c

File Facts

System
Linux kernel
Corpus path
fs/ecryptfs/crypto.c
Extension
.c
Size
59387 bytes
Lines
1986
Domain
Core OS
Bucket
VFS And Filesystem Core
Inferred role
Core OS: implementation source
Status
source implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

struct ecryptfs_flag_map_elem {
	u32 file_flag;
	u32 local_flag;
};

/* Add support for additional flags by adding elements here. */
static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = {
	{0x00000001, ECRYPTFS_ENABLE_HMAC},
	{0x00000002, ECRYPTFS_ENCRYPTED},
	{0x00000004, ECRYPTFS_METADATA_IN_XATTR},
	{0x00000008, ECRYPTFS_ENCRYPT_FILENAMES}
};

/**
 * ecryptfs_process_flags
 * @crypt_stat: The cryptographic context
 * @page_virt: Source data to be parsed
 * @bytes_read: Updated with the number of bytes read
 */
static void ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat,
				  char *page_virt, int *bytes_read)
{
	int i;
	u32 flags;

	flags = get_unaligned_be32(page_virt);
	for (i = 0; i < ARRAY_SIZE(ecryptfs_flag_map); i++)
		if (flags & ecryptfs_flag_map[i].file_flag) {
			crypt_stat->flags |= ecryptfs_flag_map[i].local_flag;
		} else
			crypt_stat->flags &= ~(ecryptfs_flag_map[i].local_flag);
	/* Version is in top 8 bits of the 32-bit flag vector */
	crypt_stat->file_version = ((flags >> 24) & 0xFF);
	(*bytes_read) = 4;
}

/**
 * write_ecryptfs_marker
 * @page_virt: The pointer to in a page to begin writing the marker
 * @written: Number of bytes written
 *
 * Marker = 0x3c81b7f5
 */
static void write_ecryptfs_marker(char *page_virt, size_t *written)
{
	u32 m_1, m_2;

	get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
	m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER);
	put_unaligned_be32(m_1, page_virt);
	page_virt += (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2);
	put_unaligned_be32(m_2, page_virt);
	(*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
}

void ecryptfs_write_crypt_stat_flags(char *page_virt,
				     struct ecryptfs_crypt_stat *crypt_stat,
				     size_t *written)
{
	u32 flags = 0;
	int i;

	for (i = 0; i < ARRAY_SIZE(ecryptfs_flag_map); i++)
		if (crypt_stat->flags & ecryptfs_flag_map[i].local_flag)
			flags |= ecryptfs_flag_map[i].file_flag;
	/* Version is in top 8 bits of the 32-bit flag vector */
	flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000);
	put_unaligned_be32(flags, page_virt);
	(*written) = 4;
}

struct ecryptfs_cipher_code_str_map_elem {
	char cipher_str[16];
	u8 cipher_code;
};

/* Add support for additional ciphers by adding elements here. The
 * cipher_code is whatever OpenPGP applications use to identify the
 * ciphers. List in order of probability. */
static struct ecryptfs_cipher_code_str_map_elem
ecryptfs_cipher_code_str_map[] = {
	{"aes",RFC2440_CIPHER_AES_128 },
	{"blowfish", RFC2440_CIPHER_BLOWFISH},
	{"des3_ede", RFC2440_CIPHER_DES3_EDE},
	{"cast5", RFC2440_CIPHER_CAST_5},
	{"twofish", RFC2440_CIPHER_TWOFISH},
	{"cast6", RFC2440_CIPHER_CAST_6},
	{"aes", RFC2440_CIPHER_AES_192},
	{"aes", RFC2440_CIPHER_AES_256}
};

Annotation

Implementation Notes