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MODSIGN: Fix 32-bit overflow in X.509 certificate validity date checking

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The current choice of lifetime for the autogenerated X.509 of 100 years,
putting the validTo date in 2112, causes problems on 32-bit systems where a
32-bit time_t wraps in 2106.  64-bit x86_64 systems seem to be unaffected.

This can result in something like:

	Loading module verification certificates
	X.509: Cert 6e03943da0f3b015ba6ed7f5e0cac4fe48680994 has expired
	MODSIGN: Problem loading in-kernel X.509 certificate (-127)

Or:

	X.509: Cert 6e03943da0f3b015ba6ed7f5e0cac4fe48680994 is not yet valid
	MODSIGN: Problem loading in-kernel X.509 certificate (-129)

Instead of turning the dates into time_t values and comparing, turn the system
clock and the ASN.1 dates into tm structs and compare those piecemeal instead.

Reported-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Josh Boyer <jwboyer@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
David Howells 2012-10-02 14:36:16 +01:00 committed by Rusty Russell
parent d5b719365e
commit a5752d11b3
3 changed files with 51 additions and 20 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

25
crypto/asymmetric_keys/x509_cert_parser.c
View file

@ -434,11 +434,10 @@ int x509_process_extension(void *context, size_t hdrlen,
/*
* Record a certificate time.
*/
static int x509_note_time(time_t *_time, size_t hdrlen,
static int x509_note_time(struct tm *tm, size_t hdrlen,
unsigned char tag,
const unsigned char *value, size_t vlen)
{
unsigned YY, MM, DD, hh, mm, ss;
const unsigned char *p = value;
#define dec2bin(X) ((X) - '0')
@ -448,30 +447,30 @@ static int x509_note_time(time_t *_time, size_t hdrlen,
/* UTCTime: YYMMDDHHMMSSZ */
if (vlen != 13)
goto unsupported_time;
YY = DD2bin(p);
if (YY > 50)
YY += 1900;
tm->tm_year = DD2bin(p);
if (tm->tm_year >= 50)
tm->tm_year += 1900;
else
YY += 2000;
tm->tm_year += 2000;
} else if (tag == ASN1_GENTIM) {
/* GenTime: YYYYMMDDHHMMSSZ */
if (vlen != 15)
goto unsupported_time;
YY = DD2bin(p) * 100 + DD2bin(p);
tm->tm_year = DD2bin(p) * 100 + DD2bin(p);
} else {
goto unsupported_time;
}
MM = DD2bin(p);
DD = DD2bin(p);
hh = DD2bin(p);
mm = DD2bin(p);
ss = DD2bin(p);
tm->tm_year -= 1900;
tm->tm_mon = DD2bin(p) - 1;
tm->tm_mday = DD2bin(p);
tm->tm_hour = DD2bin(p);
tm->tm_min = DD2bin(p);
tm->tm_sec = DD2bin(p);
if (*p != 'Z')
goto unsupported_time;
*_time = mktime(YY, MM, DD, hh, mm, ss);
return 0;
unsupported_time:

4
crypto/asymmetric_keys/x509_parser.h
View file

@ -18,8 +18,8 @@ struct x509_certificate {
char *subject; /* Name of certificate subject */
char *fingerprint; /* Key fingerprint as hex */
char *authority; /* Authority key fingerprint as hex */
time_t valid_from;
time_t valid_to;
struct tm valid_from;
struct tm valid_to;
enum pkey_algo pkey_algo : 8; /* Public key algorithm */
enum pkey_algo sig_pkey_algo : 8; /* Signature public key algorithm */
enum pkey_hash_algo sig_hash_algo : 8; /* Signature hash algorithm */

42
crypto/asymmetric_keys/x509_public_key.c
View file

@ -106,7 +106,7 @@ static int x509_check_signature(const struct public_key *pub,
static int x509_key_preparse(struct key_preparsed_payload *prep)
{
struct x509_certificate *cert;
time_t now;
struct tm now;
size_t srlen, sulen;
char *desc = NULL;
int ret;
@ -118,7 +118,14 @@ static int x509_key_preparse(struct key_preparsed_payload *prep)
pr_devel("Cert Issuer: %s\n", cert->issuer);
pr_devel("Cert Subject: %s\n", cert->subject);
pr_devel("Cert Key Algo: %s\n", pkey_algo[cert->pkey_algo]);
pr_devel("Cert Valid: %lu - %lu\n", cert->valid_from, cert->valid_to);
printk("Cert Valid From: %04ld-%02d-%02d %02d:%02d:%02d\n",
cert->valid_from.tm_year + 1900, cert->valid_from.tm_mon + 1,
cert->valid_from.tm_mday, cert->valid_from.tm_hour,
cert->valid_from.tm_min, cert->valid_from.tm_sec);
printk("Cert Valid To: %04ld-%02d-%02d %02d:%02d:%02d\n",
cert->valid_to.tm_year + 1900, cert->valid_to.tm_mon + 1,
cert->valid_to.tm_mday, cert->valid_to.tm_hour,
cert->valid_to.tm_min, cert->valid_to.tm_sec);
pr_devel("Cert Signature: %s + %s\n",
pkey_algo[cert->sig_pkey_algo],
pkey_hash_algo[cert->sig_hash_algo]);
@ -130,13 +137,38 @@ static int x509_key_preparse(struct key_preparsed_payload *prep)
goto error_free_cert;
}
now = CURRENT_TIME.tv_sec;
if (now < cert->valid_from) {
time_to_tm(CURRENT_TIME.tv_sec, 0, &now);
printk("Now: %04ld-%02d-%02d %02d:%02d:%02d\n",
now.tm_year + 1900, now.tm_mon + 1, now.tm_mday,
now.tm_hour, now.tm_min, now.tm_sec);
if (now.tm_year < cert->valid_from.tm_year ||
(now.tm_year == cert->valid_from.tm_year &&
(now.tm_mon < cert->valid_from.tm_mon ||
(now.tm_mon == cert->valid_from.tm_mon &&
(now.tm_mday < cert->valid_from.tm_mday ||
(now.tm_mday == cert->valid_from.tm_mday &&
(now.tm_hour < cert->valid_from.tm_hour ||
(now.tm_hour == cert->valid_from.tm_hour &&
(now.tm_min < cert->valid_from.tm_min ||
(now.tm_min == cert->valid_from.tm_min &&
(now.tm_sec < cert->valid_from.tm_sec
))))))))))) {
pr_warn("Cert %s is not yet valid\n", cert->fingerprint);
ret = -EKEYREJECTED;
goto error_free_cert;
}
if (now >= cert->valid_to) {
if (now.tm_year > cert->valid_to.tm_year ||
(now.tm_year == cert->valid_to.tm_year &&
(now.tm_mon > cert->valid_to.tm_mon ||
(now.tm_mon == cert->valid_to.tm_mon &&
(now.tm_mday > cert->valid_to.tm_mday ||
(now.tm_mday == cert->valid_to.tm_mday &&
(now.tm_hour > cert->valid_to.tm_hour ||
(now.tm_hour == cert->valid_to.tm_hour &&
(now.tm_min > cert->valid_to.tm_min ||
(now.tm_min == cert->valid_to.tm_min &&
(now.tm_sec > cert->valid_to.tm_sec
))))))))))) {
pr_warn("Cert %s has expired\n", cert->fingerprint);
ret = -EKEYEXPIRED;
goto error_free_cert;