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[97.113.188.82]) by smtp.gmail.com with ESMTPSA id d26sm690816pfn.86.2019.03.14.20.26.41 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 14 Mar 2019 20:26:42 -0700 (PDT) From: Richard Henderson To: qemu-devel@nongnu.org Date: Thu, 14 Mar 2019 20:26:14 -0700 Message-Id: <20190315032629.21234-9-richard.henderson@linaro.org> X-Mailer: git-send-email 2.17.2 In-Reply-To: <20190315032629.21234-1-richard.henderson@linaro.org> References: <20190315032629.21234-1-richard.henderson@linaro.org> X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2607:f8b0:4864:20::52f Subject: [Qemu-devel] [PATCH v3 08/23] ui/vnc: Use gcrypto_random_bytes for start_auth_vnc X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Gerd Hoffmann Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" Use a better interface for random numbers than rand(). Fail gracefully if for some reason we cannot use the crypto system. Cc: Gerd Hoffmann Signed-off-by: Richard Henderson Reviewed-by: Gerd Hoffmann Reviewed-by: Daniel P. Berrangé Reviewed-by: Philippe Mathieu-Daudé --- v2: Use qcrypto_random_bytes, not qemu_getrandom, as there is no need for deterministic results for this interface. v3: Fail gracefully in the event qcrypto_random_bytes fails. --- ui/vnc.c | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-) diff --git a/ui/vnc.c b/ui/vnc.c index 785edf3af1..d83f4a6ff9 100644 --- a/ui/vnc.c +++ b/ui/vnc.c @@ -43,6 +43,7 @@ #include "crypto/hash.h" #include "crypto/tlscredsanon.h" #include "crypto/tlscredsx509.h" +#include "crypto/random.h" #include "qom/object_interfaces.h" #include "qemu/cutils.h" #include "io/dns-resolver.h" @@ -2547,16 +2548,6 @@ static void authentication_failed(VncState *vs) vnc_client_error(vs); } -static void make_challenge(VncState *vs) -{ - int i; - - srand(time(NULL)+getpid()+getpid()*987654+rand()); - - for (i = 0 ; i < sizeof(vs->challenge) ; i++) - vs->challenge[i] = (int) (256.0*rand()/(RAND_MAX+1.0)); -} - static int protocol_client_auth_vnc(VncState *vs, uint8_t *data, size_t len) { unsigned char response[VNC_AUTH_CHALLENGE_SIZE]; @@ -2628,7 +2619,16 @@ reject: void start_auth_vnc(VncState *vs) { - make_challenge(vs); + Error *err = NULL; + + if (qcrypto_random_bytes(vs->challenge, sizeof(vs->challenge), &err)) { + trace_vnc_auth_fail(vs, vs->auth, "cannot get random bytes", + error_get_pretty(err)); + error_free(err); + authentication_failed(vs); + return; + } + /* Send client a 'random' challenge */ vnc_write(vs, vs->challenge, sizeof(vs->challenge)); vnc_flush(vs);