keypin.c File Reference

Functions and structures for associating routers' RSA key fingerprints with their ED25519 keys. More...

#include "orconfig.h"
#include "lib/cc/torint.h"
#include "lib/crypt_ops/crypto_digest.h"
#include "lib/crypt_ops/crypto_format.h"
#include "lib/ctime/di_ops.h"
#include "lib/encoding/binascii.h"
#include "lib/encoding/time_fmt.h"
#include "lib/fdio/fdio.h"
#include "lib/fs/files.h"
#include "lib/fs/mmap.h"
#include "lib/log/log.h"
#include "lib/log/util_bug.h"
#include "lib/string/compat_ctype.h"
#include "lib/string/printf.h"
#include "lib/wallclock/approx_time.h"
#include "ht.h"
#include "feature/dirauth/keypin.h"
#include "siphash.h"
#include <errno.h>
#include <string.h>
#include <stdlib.h>

Go to the source code of this file.

Macros
#define	KEYPIN_PRIVATE
#define	O_SYNC   0
#define	JOURNAL_LINE_LEN   (BASE64_DIGEST_LEN + BASE64_DIGEST256_LEN + 2)

Functions
static int	keypin_journal_append_entry (const uint8_t *rsa_id_digest, const uint8_t *ed25519_id_key)
static int	keypin_check_and_add_impl (const uint8_t *rsa_id_digest, const uint8_t *ed25519_id_key, const int do_not_add, const int replace)
static int	keypin_add_or_replace_entry_in_map (keypin_ent_t *ent)
static	HT_HEAD (rsamap, keypin_ent_st)
static unsigned	keypin_ent_hash_rsa (const keypin_ent_t *a)
static int	keypin_ents_eq_ed (const keypin_ent_t *a, const keypin_ent_t *b)
static unsigned	keypin_ent_hash_ed (const keypin_ent_t *a)
	HT_PROTOTYPE (rsamap, keypin_ent_st, rsamap_node, keypin_ent_hash_rsa, keypin_ents_eq_rsa)
	HT_GENERATE2 (rsamap, keypin_ent_st, rsamap_node, keypin_ent_hash_rsa, keypin_ents_eq_rsa, 0.6, tor_reallocarray, tor_free_)
	HT_PROTOTYPE (edmap, keypin_ent_st, edmap_node, keypin_ent_hash_ed, keypin_ents_eq_ed)
	HT_GENERATE2 (edmap, keypin_ent_st, edmap_node, keypin_ent_hash_ed, keypin_ents_eq_ed, 0.6, tor_reallocarray, tor_free_)
int	keypin_check_and_add (const uint8_t *rsa_id_digest, const uint8_t *ed25519_id_key, const int replace_existing_entry)
int	keypin_check (const uint8_t *rsa_id_digest, const uint8_t *ed25519_id_key)
STATIC void	keypin_add_entry_to_map (keypin_ent_t *ent)
int	keypin_check_lone_rsa (const uint8_t *rsa_id_digest)
int	keypin_open_journal (const char *fname)
int	keypin_close_journal (void)
STATIC int	keypin_load_journal_impl (const char *data, size_t size)
int	keypin_load_journal (const char *fname)
STATIC keypin_ent_t *	keypin_parse_journal_line (const char *cp)
void	keypin_clear (void)

Variables
static int	keypin_journal_fd = -1

Detailed Description

Functions and structures for associating routers' RSA key fingerprints with their ED25519 keys.

Key-pinning for RSA and Ed25519 identity keys at directory authorities.

Many older clients, and many internal interfaces, still refer to relays by their RSA1024 identity keys. We can make this more secure, however: authorities use this module to track which RSA keys have been used along with which Ed25519 keys, and force such associations to be permanent.

This module implements a key-pinning mechanism to ensure that it's safe to use RSA keys as identifiers even as we migrate to Ed25519 keys. It remembers, for every Ed25519 key we've seen, what the associated RSA key is. This way, if we see a different Ed25519 key with that RSA key, we'll know that there's a mismatch.

As of Tor 0.3.0.2-alpha the AuthDirPinKeys option has been on, meaning we drop descriptors with mismatches.

We persist these entries to disk using a simple format, where each line has a base64-encoded RSA SHA1 hash, then a base64-encoded Ed25519 key. Empty lines, malformed lines, and lines beginning with # are ignored. Lines beginning with @ are reserved for future extensions.

The dirserv.c module is the main user of these functions.

Definition in file keypin.c.

Macro Definition Documentation

JOURNAL_LINE_LEN

#define JOURNAL_LINE_LEN   (BASE64_DIGEST_LEN + BASE64_DIGEST256_LEN + 2)

Length of a keypinning journal line, including terminating newline.

Definition at line 344 of file keypin.c.

Function Documentation

keypin_add_entry_to_map()

STATIC void keypin_add_entry_to_map

(

keypin_ent_t *

ent

)

Helper: add ent to the hash tables.

Definition at line 216 of file keypin.c.

Referenced by keypin_add_or_replace_entry_in_map().

keypin_add_or_replace_entry_in_map()

static int keypin_add_or_replace_entry_in_map ( keypin_ent_t *  ent )

static

Helper: add 'ent' to the maps, replacing any entries that contradict it. Take ownership of 'ent', freeing it if needed.

Return 0 if the entry was a duplicate, -1 if there was a conflict, and 1 if there was no conflict.

Definition at line 230 of file keypin.c.

Referenced by keypin_load_journal_impl().

keypin_check()

int keypin_check	(	const uint8_t *	rsa_id_digest,
		const uint8_t *	ed25519_id_key
	)

As keypin_check_and_add, but do not add. Return KEYPIN_NOT_FOUND if we would add.

Definition at line 153 of file keypin.c.

keypin_check_and_add()

int keypin_check_and_add	(	const uint8_t *	rsa_id_digest,
		const uint8_t *	ed25519_id_key,
		const int	replace_existing_entry
	)

Check whether we already have an entry in the key pinning table for a router with RSA ID digest rsa_id_digest or for ed25519 key ed25519_id_key. If we have an entry that matches both keys, return KEYPIN_FOUND. If we find an entry that matches one key but not the other, return KEYPIN_MISMATCH. If we have no entry for either key, add such an entry to the table and return KEYPIN_ADDED.

If replace_existing_entry is true, then any time we would have said KEYPIN_FOUND, we instead add this entry anyway and return KEYPIN_ADDED.

Definition at line 140 of file keypin.c.

keypin_check_and_add_impl()

static int keypin_check_and_add_impl ( const uint8_t *  rsa_id_digest, const uint8_t *  ed25519_id_key, const int  do_not_add, const int  replace  )

static

Helper: implements keypin_check and keypin_check_and_add.

Definition at line 163 of file keypin.c.

Referenced by keypin_check(), and keypin_check_and_add().

keypin_check_lone_rsa()

int keypin_check_lone_rsa

(

const uint8_t *

rsa_id_digest

)

Check whether we already have an entry in the key pinning table for a router with RSA ID digest rsa_id_digest. If we have no such entry, return KEYPIN_NOT_FOUND. If we find an entry that matches the RSA key but which has an ed25519 key, return KEYPIN_MISMATCH.

Definition at line 280 of file keypin.c.

keypin_clear()

void keypin_clear

(

void

)

Remove all entries from the keypinning table.

Definition at line 487 of file keypin.c.

keypin_close_journal()

int keypin_close_journal

(

void

)

Close the keypinning journal file.

Definition at line 335 of file keypin.c.

keypin_ent_hash_ed()

static unsigned keypin_ent_hash_ed ( const keypin_ent_t *  a )

inlinestatic

Hashtable helper: hash a keypin table entries based on its ed25519 key

Definition at line 113 of file keypin.c.

keypin_ent_hash_rsa()

static unsigned keypin_ent_hash_rsa ( const keypin_ent_t *  a )

inlinestatic

Hashtable helper: hash a keypin table entries based on its RSA key ID

Definition at line 98 of file keypin.c.

keypin_ents_eq_ed()

static int keypin_ents_eq_ed ( const keypin_ent_t *  a, const keypin_ent_t *  b  )

inlinestatic

Hashtable helper: compare two keypin table entries and return true iff they have the same ed25519 keys

Definition at line 106 of file keypin.c.

keypin_journal_append_entry()

static int keypin_journal_append_entry ( const uint8_t *  rsa_id_digest, const uint8_t *  ed25519_id_key  )

static

Add an entry to the keypinning journal to map rsa_id_digest and ed25519_id_key.

Definition at line 349 of file keypin.c.

keypin_load_journal()

int keypin_load_journal

(

const char *

fname

)

Load a journal from the file called fname. Return 0 on success, -1 on failure.

Definition at line 448 of file keypin.c.

keypin_load_journal_impl()

STATIC int keypin_load_journal_impl	(	const char *	data,
		size_t	size
	)

Load a journal from the size-byte region at data. Return 0 on success, -1 on failure.

Definition at line 374 of file keypin.c.

keypin_open_journal()

int keypin_open_journal

(

const char *

fname

)

Open the key-pinning journal to append to fname. Return 0 on success, -1 on failure.

Definition at line 301 of file keypin.c.

keypin_parse_journal_line()

STATIC keypin_ent_t* keypin_parse_journal_line

(

const char *

cp

)

Parse a single keypinning journal line entry from cp. The input does not need to be NUL-terminated, but it does need to have KEYPIN_JOURNAL_LINE_LEN -1 bytes available to read. Return a new entry on success, and NULL on failure.

Definition at line 468 of file keypin.c.

Referenced by keypin_load_journal_impl().

Variable Documentation

keypin_journal_fd

int keypin_journal_fd = -1

static

Open fd to the keypinning journal file.

Definition at line 296 of file keypin.c.

Referenced by keypin_close_journal(), and keypin_journal_append_entry().