include/linux/key.h

Source file repositories/reference/linux-study-clean/include/linux/key.h

File Facts

System
Linux kernel
Corpus path
include/linux/key.h
Extension
.h
Size
16447 bytes
Lines
521
Domain
Core OS
Bucket
Core Kernel Interface
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 key_tag {
	struct rcu_head		rcu;
	refcount_t		usage;
	bool			removed;	/* T when subject removed */
};

struct keyring_index_key {
	/* [!] If this structure is altered, the union in struct key must change too! */
	unsigned long		hash;			/* Hash value */
	union {
		struct {
#ifdef __LITTLE_ENDIAN /* Put desc_len at the LSB of x */
			u16	desc_len;
			char	desc[sizeof(long) - 2];	/* First few chars of description */
#else
			char	desc[sizeof(long) - 2];	/* First few chars of description */
			u16	desc_len;
#endif
		};
		unsigned long x;
	};
	struct key_type		*type;
	struct key_tag		*domain_tag;	/* Domain of operation */
	const char		*description;
};

union key_payload {
	void __rcu		*rcu_data0;
	void			*data[4];
};

/*****************************************************************************/
/*
 * key reference with possession attribute handling
 *
 * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually
 * defined. This is because we abuse the bottom bit of the reference to carry a
 * flag to indicate whether the calling process possesses that key in one of
 * its keyrings.
 *
 * the key_ref_t has been made a separate type so that the compiler can reject
 * attempts to dereference it without proper conversion.
 *
 * the three functions are used to assemble and disassemble references
 */
typedef struct __key_reference_with_attributes *key_ref_t;

static inline key_ref_t make_key_ref(const struct key *key,
				     bool possession)
{
	return (key_ref_t) ((unsigned long) key | possession);
}

static inline struct key *key_ref_to_ptr(const key_ref_t key_ref)
{
	return (struct key *) ((unsigned long) key_ref & ~1UL);
}

static inline bool is_key_possessed(const key_ref_t key_ref)
{
	return (unsigned long) key_ref & 1UL;
}

typedef int (*key_restrict_link_func_t)(struct key *dest_keyring,
					const struct key_type *type,
					const union key_payload *payload,
					struct key *restriction_key);

struct key_restriction {
	key_restrict_link_func_t check;
	struct key *key;
	struct key_type *keytype;
};

enum key_state {
	KEY_IS_UNINSTANTIATED,
	KEY_IS_POSITIVE,		/* Positively instantiated */
};

/*****************************************************************************/
/*
 * authentication token / access credential / keyring
 * - types of key include:
 *   - keyrings
 *   - disk encryption IDs
 *   - Kerberos TGTs and tickets
 */
struct key {
	refcount_t		usage;		/* number of references */
	key_serial_t		serial;		/* key serial number */

Annotation

Implementation Notes