RSA PKCS1v1.5 verification: check padding length
The test case was generated by modifying our signature code so that it
produces a 7-byte long padding (which also means garbage at the end, so it is
essential in to check that the error that is detected first is indeed the
padding rather than the final length check).
diff --git a/ChangeLog b/ChangeLog
index 13de867..4340b42 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,11 @@
mbed TLS ChangeLog (Sorted per branch, date)
+= mbed TLS 2.x.x branch released xxxx-xx-xx
+
+Security
+ * Tighten parsing of RSA PKCS#1 v1.5 signatures, to avoid a
+ potential Bleichenbacher/BERserk-style attack.
+
= mbed TLS 2.4.2 branch released 2017-03-08
Security
diff --git a/library/rsa.c b/library/rsa.c
index 40ef2a9..c8c6d99 100644
--- a/library/rsa.c
+++ b/library/rsa.c
@@ -1369,7 +1369,11 @@
return( MBEDTLS_ERR_RSA_INVALID_PADDING );
p++;
}
- p++;
+ p++; /* skip 00 byte */
+
+ /* We've read: 00 01 PS 00 where PS must be at least 8 bytes */
+ if( p - buf < 11 )
+ return( MBEDTLS_ERR_RSA_INVALID_PADDING );
len = siglen - ( p - buf );
diff --git a/tests/suites/test_suite_rsa.data b/tests/suites/test_suite_rsa.data
index af16880..5013ac8 100644
--- a/tests/suites/test_suite_rsa.data
+++ b/tests/suites/test_suite_rsa.data
@@ -134,6 +134,10 @@
depends_on:MBEDTLS_SHA512_C:MBEDTLS_PKCS1_V15
mbedtls_rsa_pkcs1_verify:"59779fd2a39e56640c4fc1e67b60aeffcecd78aed7ad2bdfa464e93d04198d48466b8da7445f25bfa19db2844edd5c8f539cf772cc132b483169d390db28a43bc4ee0f038f6568ffc87447746cb72fefac2d6d90ee3143a915ac4688028805905a68eb8f8a96674b093c495eddd8704461eaa2b345efbb2ad6930acd8023f870":MBEDTLS_RSA_PKCS_V15:MBEDTLS_MD_SHA512:1536:16:"a59d9b7269b102b7be684ec5e28db79992e6d3231e77c90b78960c2638b35ef6dbdac1ac59e7249d96d426e7f99397eabc6b8903fe1942da580322b98bafacd81bb911c29666f83886a2a2864f3552044300e60cedd5a8c321c43e280413dc41673c39a11b98a885486f8187a70f270185c4c12bc48a1968305269776c070ef69d4913589a887c4d0f5e7dd58bd806d0d49a14a1762c38665cef4646ff13a0cd29c3a60460703c3d051d5b28c660bffb5f8bd43d495ffa64175f72b8abe5fddd":16:"11":"0b4d96f411c727a262d6d0ade34195b78603551061917d060f89add47b09dfe8715f4f9147d327dc25e91fe457e5d1a2f22cd8fe6fe8e29d2060658307c87a40640650fef3d4b289a6c3febc5a100b29a8b56623afb29fd3c13ea372bf3c638c1db25f8bd8c74c821beec7b5affcace1d05d056a6c2d3035926c7a268df4751a54bc20a6b8cfd729a7cba309ae817daccbef9950a482cf23950a8ca1d3a13ddb7d8d0f87ad5587d4d9ebe19fe93457597a7bdd056c2fd4cea7d31e4a0e595a7b":0
+RSA PKCS1 Verify v1.5 padding too short
+depends_on:MBEDTLS_SHA1_C:MBEDTLS_PKCS1_V15
+mbedtls_rsa_pkcs1_verify:"AABBCC03020100FFFFFFFFFF1122330A0B0CCCDDDDDDDDDD":MBEDTLS_RSA_PKCS_V15:MBEDTLS_MD_SHA1:1024:16:"9292758453063D803DD603D5E777D7888ED1D5BF35786190FA2F23EBC0848AEADDA92CA6C3D80B32C4D109BE0F36D6AE7130B9CED7ACDF54CFC7555AC14EEBAB93A89813FBF3C4F8066D2D800F7C38A81AE31942917403FF4946B0A83D3D3E05EE57C6F5F5606FB5D4BC6CD34EE0801A5E94BB77B07507233A0BC7BAC8F90F79":16:"10001":"6edd56f397d9bc6d176bbe3d80946fc352ad6127b85b1d67d849c0a38cbde7222c5fafbb18dcef791178a8e15f5c8cd91869f8ca4b758c46ce3e229bf666d2e3e296544351bcb5db7e0004f6c0800f76a432071297e405759d4324d1cf1c412758be93a39f834e03dee59e28ac571ce2b0b3c8fe639979f516223b54027340a5":MBEDTLS_ERR_RSA_INVALID_PADDING
+
RSA PKCS1 Sign #1 (SHA512, 1536 bits RSA)
depends_on:MBEDTLS_SHA512_C:MBEDTLS_PKCS1_V15
mbedtls_rsa_pkcs1_sign:"59779fd2a39e56640c4fc1e67b60aeffcecd78aed7ad2bdfa464e93d04198d48466b8da7445f25bfa19db2844edd5c8f539cf772cc132b483169d390db28a43bc4ee0f038f6568ffc87447746cb72fefac2d6d90ee3143a915ac4688028805905a68eb8f8a96674b093c495eddd8704461eaa2b345efbb2ad6930acd8023f870":MBEDTLS_RSA_PKCS_V15:MBEDTLS_MD_SHA512:1536:16:"c8c67df894c882045ede26a9008ab09ea0672077d7bc71d412511cd93981ddde8f91b967da404056c39f105f7f239abdaff92923859920f6299e82b95bd5b8c959948f4a035cbd693ad83014294d349813d1ad57911a6355d0731fe3a034e9db":16:"f15147d0e7c04a1e3f37adde802cdc610999bf7ab0088434aaeda0c0ab3910b14d2ce56cb66bffd97552195fae8b061077e03920814d8b9cfb5a3958b3a82c2a7fc97e55db5978b47a922156eb8a3e55c06a54a45d1670abdfb995489c4d0051":16:"bd429bb7c3b00bbea19ba664c0f8172d1a73c3cfa05e2ed656d570c1590918bb7e372ed25e2cd71395ba0a9b1a30f3ee012ffb0546cab8e3581fe3e23f44ab57a8aee9717e71a936a580fa8572d450fb00339a6f6704b717df0c149a465bab768c61500cd93b61113ff3e4389167f7b2c8e3c0da2d4765286bee555b0bcb4998f59b14fad03180a17c8b4f69bcd1234f4ae85950137665ac2ba80b55cc9b1aafb454b83771aa755acd2a00e93ddb65e696dbed8bdca69fb5e0c5c2097b9cfe4b":16:"3":"93b6fa99485c116ca6efdd4202ea1cf49f4c6345fae692584413743ce5b65510e8e4690aee9a19ea1ff10d57f22aa3548d839f28a8525a34354e9e58e0f3947e056ce2554e21bf287e220b98db3b551258cd42b495e5d1a3bbc83c9d1a02f2a300ef6d866ea75108e44ebb3e16b47df2f6de28feb2be3874dbbf21599451082d86e9f2f462575a8185c69aa1f1fcb6a363c5d71aeba2103449eaf3845285291148d5f78d1646b8dc95cbcc4082f987d948b0e7d4e80b60595f8a7517584e1643":0
