One time test at startup to ensure either kernel version v4.9 or later,
*or* that required AES-CCM support has been back-ported. If support not
there, daemon will run without providing D-Bus service or attaching to
controllers (prevents systemd thrashing).
---
mesh/crypto.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
mesh/crypto.h | 1 +
mesh/main.c | 7 +++++++
3 files changed, 59 insertions(+)
diff --git a/mesh/crypto.c b/mesh/crypto.c
index a6dc7ffe2..27d1a16cc 100644
--- a/mesh/crypto.c
+++ b/mesh/crypto.c
@@ -1130,3 +1130,54 @@ bool mesh_crypto_check_fcs(const uint8_t *packet, uint8_t packet_len,
return fcs == 0xcf;
}
+
+/* This function performs a quick-check of ELL and Kernel AEAD encryption.
+ * Some kernel versions before v4.9 have a known AEAD bug. If the system
+ * running this test is using a v4.8 or earlier kernel, a failure here is
+ * likely unless AEAD encryption has been backported.
+ */
+static const uint8_t crypto_test_result[] = {
+ 0x75, 0x03, 0x7e, 0xe2, 0x89, 0x81, 0xbe, 0x59,
+ 0xbc, 0xe6, 0xdd, 0x23, 0x63, 0x5b, 0x16, 0x61,
+ 0xb7, 0x23, 0x92, 0xd4, 0x86, 0xee, 0x84, 0x29,
+ 0x9a, 0x2a, 0xbf, 0x96
+};
+bool mesh_crypto_check_avail()
+{
+ void *cipher;
+ bool result;
+ uint8_t i;
+ union {
+ struct {
+ uint8_t key[16];
+ uint8_t aad[16];
+ uint8_t nonce[13];
+ uint8_t data[20];
+ uint8_t mic[8];
+ } crypto;
+ uint8_t bytes[0];
+ } u;
+ uint8_t out_msg[sizeof(u.crypto.data) + sizeof(u.crypto.mic)];
+
+
+ l_debug("Testing Crypto");
+ for (i = 0; i < sizeof(u); i++) {
+ u.bytes[i] = 0x60 + i;
+ }
+
+ cipher = l_aead_cipher_new(L_AEAD_CIPHER_AES_CCM, u.crypto.key,
+ sizeof(u.crypto.key), sizeof(u.crypto.mic));
+
+ result = l_aead_cipher_encrypt(cipher,
+ u.crypto.data, sizeof(u.crypto.data),
+ u.crypto.aad, sizeof(u.crypto.aad),
+ u.crypto.nonce, sizeof(u.crypto.nonce),
+ out_msg, sizeof(out_msg));
+
+ if (result)
+ result = !memcmp(out_msg, crypto_test_result, sizeof(out_msg));
+
+ l_aead_cipher_free(cipher);
+
+ return result;
+}
diff --git a/mesh/crypto.h b/mesh/crypto.h
index 1a73bcaa3..e5ce840b4 100644
--- a/mesh/crypto.h
+++ b/mesh/crypto.h
@@ -161,3 +161,4 @@ bool mesh_crypto_check_fcs(const uint8_t *packet, uint8_t packet_len,
uint8_t received_fcs);
bool mesh_crypto_aes_cmac(const uint8_t key[16], const uint8_t *msg,
size_t msg_len, uint8_t res[16]);
+bool mesh_crypto_check_avail(void);
diff --git a/mesh/main.c b/mesh/main.c
index 262e3da48..273651f97 100644
--- a/mesh/main.c
+++ b/mesh/main.c
@@ -34,6 +34,7 @@
#include "lib/mgmt.h"
#include "mesh/mesh.h"
+#include "mesh/crypto.h"
#include "mesh/dbus.h"
#include "mesh/mesh-io.h"
@@ -121,6 +122,12 @@ int main(int argc, char *argv[])
l_log_set_stderr();
+ if (!mesh_crypto_check_avail()) {
+ l_error("Mesh Crypto functions unavailable");
+ status = l_main_run_with_signal(signal_handler, NULL);
+ goto done;
+ }
+
for (;;) {
int opt;
const char *str;
--
2.21.0
Hi Brian,
There's also l_aead_cipher_is_supported(L_AEAD_CIPHER_AES_CCM), which
might fail more cleanly on systems with old kernels or that don't have
AES_CCM configured. I suggest doing that check first and then proceeding
to the bug check if AES_CCM is available.
Mat
On Fri, 30 Aug 2019, Brian Gix wrote:
> One time test at startup to ensure either kernel version v4.9 or later,
> *or* that required AES-CCM support has been back-ported. If support not
> there, daemon will run without providing D-Bus service or attaching to
> controllers (prevents systemd thrashing).
> ---
> mesh/crypto.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
> mesh/crypto.h | 1 +
> mesh/main.c | 7 +++++++
> 3 files changed, 59 insertions(+)
>
> diff --git a/mesh/crypto.c b/mesh/crypto.c
> index a6dc7ffe2..27d1a16cc 100644
> --- a/mesh/crypto.c
> +++ b/mesh/crypto.c
> @@ -1130,3 +1130,54 @@ bool mesh_crypto_check_fcs(const uint8_t *packet, uint8_t packet_len,
>
> return fcs == 0xcf;
> }
> +
> +/* This function performs a quick-check of ELL and Kernel AEAD encryption.
> + * Some kernel versions before v4.9 have a known AEAD bug. If the system
> + * running this test is using a v4.8 or earlier kernel, a failure here is
> + * likely unless AEAD encryption has been backported.
> + */
> +static const uint8_t crypto_test_result[] = {
> + 0x75, 0x03, 0x7e, 0xe2, 0x89, 0x81, 0xbe, 0x59,
> + 0xbc, 0xe6, 0xdd, 0x23, 0x63, 0x5b, 0x16, 0x61,
> + 0xb7, 0x23, 0x92, 0xd4, 0x86, 0xee, 0x84, 0x29,
> + 0x9a, 0x2a, 0xbf, 0x96
> +};
> +bool mesh_crypto_check_avail()
> +{
> + void *cipher;
> + bool result;
> + uint8_t i;
> + union {
> + struct {
> + uint8_t key[16];
> + uint8_t aad[16];
> + uint8_t nonce[13];
> + uint8_t data[20];
> + uint8_t mic[8];
> + } crypto;
> + uint8_t bytes[0];
> + } u;
> + uint8_t out_msg[sizeof(u.crypto.data) + sizeof(u.crypto.mic)];
> +
> +
> + l_debug("Testing Crypto");
> + for (i = 0; i < sizeof(u); i++) {
> + u.bytes[i] = 0x60 + i;
> + }
> +
> + cipher = l_aead_cipher_new(L_AEAD_CIPHER_AES_CCM, u.crypto.key,
> + sizeof(u.crypto.key), sizeof(u.crypto.mic));
> +
> + result = l_aead_cipher_encrypt(cipher,
> + u.crypto.data, sizeof(u.crypto.data),
> + u.crypto.aad, sizeof(u.crypto.aad),
> + u.crypto.nonce, sizeof(u.crypto.nonce),
> + out_msg, sizeof(out_msg));
> +
> + if (result)
> + result = !memcmp(out_msg, crypto_test_result, sizeof(out_msg));
> +
> + l_aead_cipher_free(cipher);
> +
> + return result;
> +}
> diff --git a/mesh/crypto.h b/mesh/crypto.h
> index 1a73bcaa3..e5ce840b4 100644
> --- a/mesh/crypto.h
> +++ b/mesh/crypto.h
> @@ -161,3 +161,4 @@ bool mesh_crypto_check_fcs(const uint8_t *packet, uint8_t packet_len,
> uint8_t received_fcs);
> bool mesh_crypto_aes_cmac(const uint8_t key[16], const uint8_t *msg,
> size_t msg_len, uint8_t res[16]);
> +bool mesh_crypto_check_avail(void);
> diff --git a/mesh/main.c b/mesh/main.c
> index 262e3da48..273651f97 100644
> --- a/mesh/main.c
> +++ b/mesh/main.c
> @@ -34,6 +34,7 @@
> #include "lib/mgmt.h"
>
> #include "mesh/mesh.h"
> +#include "mesh/crypto.h"
> #include "mesh/dbus.h"
> #include "mesh/mesh-io.h"
>
> @@ -121,6 +122,12 @@ int main(int argc, char *argv[])
>
> l_log_set_stderr();
>
> + if (!mesh_crypto_check_avail()) {
> + l_error("Mesh Crypto functions unavailable");
> + status = l_main_run_with_signal(signal_handler, NULL);
> + goto done;
> + }
> +
> for (;;) {
> int opt;
> const char *str;
> --
> 2.21.0
>
>
--
Mat Martineau
Intel
Brian,
On 08/30, Brian Gix wrote:
> One time test at startup to ensure either kernel version v4.9 or later,
> *or* that required AES-CCM support has been back-ported. If support not
> there, daemon will run without providing D-Bus service or attaching to
> controllers (prevents systemd thrashing).
By the way - I have a patch that implements all required cryptographic
operations using libcrypto, enabled by ./configure --with-openssl
(disabled by default).
I know that last time we've talked about this, the consensus was that the
vendor should patch meshd to work on older kernels, so we did exactly
that - but maybe having this available in the mainline would be
interesting?
regards
--
Michał Lowas-Rzechonek <[email protected]>
Silvair http://silvair.com
Jasnogórska 44, 31-358 Krakow, POLAND
On Fri, 2019-08-30 at 20:23 +0200, Michał Lowas-Rzechonek wrote:
> Brian,
>
> On 08/30, Brian Gix wrote:
> > One time test at startup to ensure either kernel version v4.9 or later,
> > *or* that required AES-CCM support has been back-ported. If support not
> > there, daemon will run without providing D-Bus service or attaching to
> > controllers (prevents systemd thrashing).
>
> By the way - I have a patch that implements all required cryptographic
> operations using libcrypto, enabled by ./configure --with-openssl
> (disabled by default).
>
> I know that last time we've talked about this, the consensus was that the
> vendor should patch meshd to work on older kernels, so we did exactly
> that - but maybe having this available in the mainline would be
> interesting?
Yeah, we have talked internally about how much "old kernel support" cruft can be removed, which is one of the
things Marcel would want before doing a "Major Version Number Release" like "BlueZ-6.0", where we could say
that v6.0 requires a minimum kernel version of v4.9 or something... As opposed to a minor version release like
"BlueZ-5.51" which has support for most v4.X kernels. Perhaps something like openssl could be *suggested* in a
README as one of a few possible work-arounds a vendor could use to run on an older kernel, but there is no
support for adding an openssl dependancy into the BlueZ mainline tip.
On 08/30, Gix, Brian wrote:
> > I know that last time we've talked about this, the consensus was that the
> > vendor should patch meshd to work on older kernels, so we did exactly
> > that - but maybe having this available in the mainline would be
> > interesting?
>
> Perhaps something like openssl could be *suggested* in a README as one
> of a few possible work-arounds a vendor could use to run on an older
> kernel, but there is no support for adding an openssl dependancy into
> the BlueZ mainline tip.
Ack.
--
Michał Lowas-Rzechonek <[email protected]>
Silvair http://silvair.com
Jasnogórska 44, 31-358 Krakow, POLAND
Hi Michal,
>> One time test at startup to ensure either kernel version v4.9 or later,
>> *or* that required AES-CCM support has been back-ported. If support not
>> there, daemon will run without providing D-Bus service or attaching to
>> controllers (prevents systemd thrashing).
>
> By the way - I have a patch that implements all required cryptographic
> operations using libcrypto, enabled by ./configure --with-openssl
> (disabled by default).
>
> I know that last time we've talked about this, the consensus was that the
> vendor should patch meshd to work on older kernels, so we did exactly
> that - but maybe having this available in the mainline would be
> interesting?
we are not using anything from OpenSSL. That is a rabbit hole you are not getting back out of.
Regards
Marcel