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Date: Wed, 05 Aug 2015 14:47:30 +0100
From: David Howells <dhowells@...hat.com>
To: keyrings@...ux-nfs.org
Cc: mcgrof@...il.com, zohar@...ux.vnet.ibm.com, kyle@...nel.org,
linux-kernel@...r.kernel.org,
linux-security-module@...r.kernel.org, dwmw2@...radead.org
Subject: [PATCH 24/27] PKCS#7: Improve and export the X.509 ASN.1 time
object decoder [ver #7]
Make the X.509 ASN.1 time object decoder fill in a time64_t rather than a
struct tm to make comparison easier (unfortunately, this makes readable
display less easy) and export it so that it can be used by the PKCS#7 code
too.
Further, tighten up its parsing to reject invalid dates (eg. weird
characters, non-existent hour numbers) and unsupported dates (eg. timezones
other than 'Z' or dates earlier than 1970).
Signed-off-by: David Howells <dhowells@...hat.com>
Reviewed-by: David Woodhouse <David.Woodhouse@...el.com>
---
crypto/asymmetric_keys/x509_cert_parser.c | 87 ++++++++++++++++++++++-------
crypto/asymmetric_keys/x509_parser.h | 7 ++
crypto/asymmetric_keys/x509_public_key.c | 9 ---
3 files changed, 72 insertions(+), 31 deletions(-)
diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c
index 849fd760923e..af71878dc15b 100644
--- a/crypto/asymmetric_keys/x509_cert_parser.c
+++ b/crypto/asymmetric_keys/x509_cert_parser.c
@@ -472,60 +472,105 @@ int x509_process_extension(void *context, size_t hdrlen,
return 0;
}
-/*
- * Record a certificate time.
+/**
+ * x509_decode_time - Decode an X.509 time ASN.1 object
+ * @_t: The time to fill in
+ * @hdrlen: The length of the object header
+ * @tag: The object tag
+ * @value: The object value
+ * @vlen: The size of the object value
+ *
+ * Decode an ASN.1 universal time or generalised time field into a struct the
+ * kernel can handle and check it for validity. The time is decoded thus:
+ *
+ * [RFC5280 ยง4.1.2.5]
+ * CAs conforming to this profile MUST always encode certificate validity
+ * dates through the year 2049 as UTCTime; certificate validity dates in
+ * 2050 or later MUST be encoded as GeneralizedTime. Conforming
+ * applications MUST be able to process validity dates that are encoded in
+ * either UTCTime or GeneralizedTime.
*/
-static int x509_note_time(struct tm *tm, size_t hdrlen,
- unsigned char tag,
- const unsigned char *value, size_t vlen)
+int x509_decode_time(time64_t *_t, size_t hdrlen,
+ unsigned char tag,
+ const unsigned char *value, size_t vlen)
{
+ static const unsigned char month_lengths[] = { 31, 29, 31, 30, 31, 30,
+ 31, 31, 30, 31, 30, 31 };
const unsigned char *p = value;
+ unsigned year, mon, day, hour, min, sec, mon_len;
-#define dec2bin(X) ((X) - '0')
+#define dec2bin(X) ({ unsigned char x = (X) - '0'; if (x > 9) goto invalid_time; x; })
#define DD2bin(P) ({ unsigned x = dec2bin(P[0]) * 10 + dec2bin(P[1]); P += 2; x; })
if (tag == ASN1_UNITIM) {
/* UTCTime: YYMMDDHHMMSSZ */
if (vlen != 13)
goto unsupported_time;
- tm->tm_year = DD2bin(p);
- if (tm->tm_year >= 50)
- tm->tm_year += 1900;
+ year = DD2bin(p);
+ if (year >= 50)
+ year += 1900;
else
- tm->tm_year += 2000;
+ year += 2000;
} else if (tag == ASN1_GENTIM) {
/* GenTime: YYYYMMDDHHMMSSZ */
if (vlen != 15)
goto unsupported_time;
- tm->tm_year = DD2bin(p) * 100 + DD2bin(p);
+ year = DD2bin(p) * 100 + DD2bin(p);
+ if (year >= 1950 && year <= 2049)
+ goto invalid_time;
} else {
goto unsupported_time;
}
- 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);
+ mon = DD2bin(p);
+ day = DD2bin(p);
+ hour = DD2bin(p);
+ min = DD2bin(p);
+ sec = DD2bin(p);
if (*p != 'Z')
goto unsupported_time;
+ mon_len = month_lengths[mon];
+ if (mon == 2) {
+ if (year % 4 == 0) {
+ mon_len = 29;
+ if (year % 100 == 0) {
+ year /= 100;
+ if (year % 4 != 0)
+ mon_len = 28;
+ }
+ }
+ }
+
+ if (year < 1970 ||
+ mon < 1 || mon > 12 ||
+ day < 1 || day > mon_len ||
+ hour < 0 || hour > 23 ||
+ min < 0 || min > 59 ||
+ sec < 0 || sec > 59)
+ goto invalid_time;
+
+ *_t = mktime64(year, mon, day, hour, min, sec);
return 0;
unsupported_time:
- pr_debug("Got unsupported time [tag %02x]: '%*.*s'\n",
- tag, (int)vlen, (int)vlen, value);
+ pr_debug("Got unsupported time [tag %02x]: '%*phN'\n",
+ tag, (int)vlen, value);
+ return -EBADMSG;
+invalid_time:
+ pr_debug("Got invalid time [tag %02x]: '%*phN'\n",
+ tag, (int)vlen, value);
return -EBADMSG;
}
+EXPORT_SYMBOL_GPL(x509_decode_time);
int x509_note_not_before(void *context, size_t hdrlen,
unsigned char tag,
const void *value, size_t vlen)
{
struct x509_parse_context *ctx = context;
- return x509_note_time(&ctx->cert->valid_from, hdrlen, tag, value, vlen);
+ return x509_decode_time(&ctx->cert->valid_from, hdrlen, tag, value, vlen);
}
int x509_note_not_after(void *context, size_t hdrlen,
@@ -533,7 +578,7 @@ int x509_note_not_after(void *context, size_t hdrlen,
const void *value, size_t vlen)
{
struct x509_parse_context *ctx = context;
- return x509_note_time(&ctx->cert->valid_to, hdrlen, tag, value, vlen);
+ return x509_decode_time(&ctx->cert->valid_to, hdrlen, tag, value, vlen);
}
/*
diff --git a/crypto/asymmetric_keys/x509_parser.h b/crypto/asymmetric_keys/x509_parser.h
index dcdb5c94f514..1de01eaec884 100644
--- a/crypto/asymmetric_keys/x509_parser.h
+++ b/crypto/asymmetric_keys/x509_parser.h
@@ -23,8 +23,8 @@ struct x509_certificate {
struct asymmetric_key_id *skid; /* Subject + subjectKeyId (optional) */
struct asymmetric_key_id *akid_id; /* CA AuthKeyId matching ->id (optional) */
struct asymmetric_key_id *akid_skid; /* CA AuthKeyId matching ->skid (optional) */
- struct tm valid_from;
- struct tm valid_to;
+ time64_t valid_from;
+ time64_t valid_to;
const void *tbs; /* Signed data */
unsigned tbs_size; /* Size of signed data */
unsigned raw_sig_size; /* Size of sigature */
@@ -49,6 +49,9 @@ struct x509_certificate {
*/
extern void x509_free_certificate(struct x509_certificate *cert);
extern struct x509_certificate *x509_cert_parse(const void *data, size_t datalen);
+extern int x509_decode_time(time64_t *_t, size_t hdrlen,
+ unsigned char tag,
+ const unsigned char *value, size_t vlen);
/*
* x509_public_key.c
diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c
index 6b060b290e77..6d88dd15c98d 100644
--- a/crypto/asymmetric_keys/x509_public_key.c
+++ b/crypto/asymmetric_keys/x509_public_key.c
@@ -302,14 +302,7 @@ static int x509_key_preparse(struct key_preparsed_payload *prep)
}
pr_devel("Cert Key Algo: %s\n", pkey_algo_name[cert->pub->pkey_algo]);
- pr_devel("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);
- pr_devel("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 Valid period: %lld-%lld\n", cert->valid_from, cert->valid_to);
pr_devel("Cert Signature: %s + %s\n",
pkey_algo_name[cert->sig.pkey_algo],
hash_algo_name[cert->sig.pkey_hash_algo]);
--
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