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Fix d2i_*_bio on partial reads.

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If BIO_read returns partial reads, d2i_*_bio currently fails. This is a
partial (hah) regression from 419144adce.
The old a_d2i_fp.c code did *not* tolerate partial reads in the ASN.1
header, but it *did* tolerate them in the ASN.1 body. Since partial
reads are more likely to land in the body than the header, I think we
can say d2i_*_bio was "supposed to" tolerate this but had a bug in the
first few bytes.

Fix it for both cases. Add a regression test for this and the partial
write case (which works fine).

See also https://github.com/google/conscrypt/pull/587.

Change-Id: I886f6388f0b80621960e196cf2a56f5c02a14a04
Reviewed-on: https://boringssl-review.googlesource.com/c/33484
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: Adam Langley <agl@google.com>
This commit is contained in:
David Benjamin 2018-12-05 13:12:48 -06:00 committed by CQ bot account: commit-bot@chromium.org
parent ff433815b5
commit 750fea158a
3 changed files with 98 additions and 15 deletions
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52
crypto/bio/bio.c
View File

@ -482,6 +482,31 @@ static int bio_read_all(BIO *bio, uint8_t **out, size_t *out_len,
}
}
// bio_read_full reads |len| bytes |bio| and writes them into |out|. It
// tolerates partial reads from |bio| and returns one on success or zero if a
// read fails before |len| bytes are read. On failure, it additionally sets
// |*out_eof_on_first_read| to whether the error was due to |bio| returning zero
// on the first read. |out_eof_on_first_read| may be NULL to discard the value.
static int bio_read_full(BIO *bio, uint8_t *out, int *out_eof_on_first_read,
size_t len) {
int first_read = 1;
while (len > 0) {
int todo = len <= INT_MAX ? (int)len : INT_MAX;
int ret = BIO_read(bio, out, todo);
if (ret <= 0) {
if (out_eof_on_first_read != NULL) {
*out_eof_on_first_read = first_read && ret == 0;
}
return 0;
}
out += ret;
len -= (size_t)ret;
first_read = 0;
}
return 1;
}
// For compatibility with existing |d2i_*_bio| callers, |BIO_read_asn1| uses
// |ERR_LIB_ASN1| errors.
OPENSSL_DECLARE_ERROR_REASON(ASN1, ASN1_R_DECODE_ERROR)
@ -493,17 +518,16 @@ int BIO_read_asn1(BIO *bio, uint8_t **out, size_t *out_len, size_t max_len) {
uint8_t header[6];
static const size_t kInitialHeaderLen = 2;
int ret = BIO_read(bio, header, kInitialHeaderLen);
if (ret == 0) {
// Historically, OpenSSL returned |ASN1_R_HEADER_TOO_LONG| when |d2i_*_bio|
// could not read anything. CPython conditions on this to determine if |bio|
// was empty.
OPENSSL_PUT_ERROR(ASN1, ASN1_R_HEADER_TOO_LONG);
return 0;
}
if (ret != (int) kInitialHeaderLen) {
OPENSSL_PUT_ERROR(ASN1, ASN1_R_NOT_ENOUGH_DATA);
int eof_on_first_read;
if (!bio_read_full(bio, header, &eof_on_first_read, kInitialHeaderLen)) {
if (eof_on_first_read) {
// Historically, OpenSSL returned |ASN1_R_HEADER_TOO_LONG| when
// |d2i_*_bio| could not read anything. CPython conditions on this to
// determine if |bio| was empty.
OPENSSL_PUT_ERROR(ASN1, ASN1_R_HEADER_TOO_LONG);
} else {
OPENSSL_PUT_ERROR(ASN1, ASN1_R_NOT_ENOUGH_DATA);
}
return 0;
}
@ -539,8 +563,7 @@ int BIO_read_asn1(BIO *bio, uint8_t **out, size_t *out_len, size_t max_len) {
return 0;
}
if (BIO_read(bio, header + kInitialHeaderLen, num_bytes) !=
(int)num_bytes) {
if (!bio_read_full(bio, header + kInitialHeaderLen, NULL, num_bytes)) {
OPENSSL_PUT_ERROR(ASN1, ASN1_R_NOT_ENOUGH_DATA);
return 0;
}
@ -582,8 +605,7 @@ int BIO_read_asn1(BIO *bio, uint8_t **out, size_t *out_len, size_t max_len) {
return 0;
}
OPENSSL_memcpy(*out, header, header_len);
if (BIO_read(bio, (*out) + header_len, len - header_len) !=
(int) (len - header_len)) {
if (!bio_read_full(bio, (*out) + header_len, NULL, len - header_len)) {
OPENSSL_PUT_ERROR(ASN1, ASN1_R_NOT_ENOUGH_DATA);
OPENSSL_free(*out);
return 0;

60
crypto/x509/x509_test.cc
View File

@ -12,6 +12,7 @@
* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
#include <algorithm>
#include <functional>
#include <string>
#include <vector>
@ -1684,3 +1685,62 @@ TEST(X509Test, ReadBIOEmpty) {
EXPECT_EQ(ERR_LIB_ASN1, ERR_GET_LIB(err));
EXPECT_EQ(ASN1_R_HEADER_TOO_LONG, ERR_GET_REASON(err));
}
TEST(X509Test, ReadBIOOneByte) {
bssl::UniquePtr<BIO> bio(BIO_new_mem_buf("\x30", 1));
ASSERT_TRUE(bio);
// CPython expects |ASN1_R_HEADER_TOO_LONG| on EOF, to terminate a series of
// certificates. This EOF appeared after some data, however, so we do not wish
// to signal EOF.
bssl::UniquePtr<X509> x509(d2i_X509_bio(bio.get(), nullptr));
EXPECT_FALSE(x509);
uint32_t err = ERR_get_error();
EXPECT_EQ(ERR_LIB_ASN1, ERR_GET_LIB(err));
EXPECT_EQ(ASN1_R_NOT_ENOUGH_DATA, ERR_GET_REASON(err));
}
TEST(X509Test, PartialBIOReturn) {
// Create a filter BIO that only reads and writes one byte at a time.
bssl::UniquePtr<BIO_METHOD> method(BIO_meth_new(0, nullptr));
ASSERT_TRUE(method);
ASSERT_TRUE(BIO_meth_set_create(method.get(), [](BIO *b) -> int {
BIO_set_init(b, 1);
return 1;
}));
ASSERT_TRUE(
BIO_meth_set_read(method.get(), [](BIO *b, char *out, int len) -> int {
return BIO_read(BIO_next(b), out, std::min(len, 1));
}));
ASSERT_TRUE(BIO_meth_set_write(
method.get(), [](BIO *b, const char *in, int len) -> int {
return BIO_write(BIO_next(b), in, std::min(len, 1));
}));
bssl::UniquePtr<BIO> bio(BIO_new(method.get()));
ASSERT_TRUE(bio);
BIO *mem_bio = BIO_new(BIO_s_mem());
ASSERT_TRUE(mem_bio);
BIO_push(bio.get(), mem_bio); // BIO_push takes ownership.
bssl::UniquePtr<X509> cert(CertFromPEM(kLeafPEM));
ASSERT_TRUE(cert);
uint8_t *der = nullptr;
int der_len = i2d_X509(cert.get(), &der);
ASSERT_GT(der_len, 0);
bssl::UniquePtr<uint8_t> free_der(der);
// Write the certificate into the BIO. Though we only write one byte at a
// time, the write should succeed.
ASSERT_EQ(1, i2d_X509_bio(bio.get(), cert.get()));
const uint8_t *der2;
size_t der2_len;
ASSERT_TRUE(BIO_mem_contents(mem_bio, &der2, &der2_len));
EXPECT_EQ(Bytes(der, static_cast<size_t>(der_len)), Bytes(der2, der2_len));
// Read the certificate back out of the BIO. Though we only read one byte at a
// time, the read should succeed.
bssl::UniquePtr<X509> cert2(d2i_X509_bio(bio.get(), nullptr));
ASSERT_TRUE(cert2);
EXPECT_EQ(0, X509_cmp(cert.get(), cert2.get()));
}

1
include/openssl/bio.h
View File

@ -904,6 +904,7 @@ BSSL_NAMESPACE_BEGIN
BORINGSSL_MAKE_DELETER(BIO, BIO_free)
BORINGSSL_MAKE_UP_REF(BIO, BIO_up_ref)
BORINGSSL_MAKE_DELETER(BIO_METHOD, BIO_meth_free)
BSSL_NAMESPACE_END