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[97.113.188.82]) by smtp.gmail.com with ESMTPSA id d26sm690816pfn.86.2019.03.14.20.26.36 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 14 Mar 2019 20:26:37 -0700 (PDT) From: Richard Henderson To: qemu-devel@nongnu.org Date: Thu, 14 Mar 2019 20:26:11 -0700 Message-Id: <20190315032629.21234-6-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> MIME-Version: 1.0 X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2607:f8b0:4864:20::42f Subject: [Qemu-devel] [PATCH v3 05/23] crypto: Use getrandom for qcrypto_random_bytes 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: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" Prefer it to direct use of /dev/urandom. Cc: Daniel P. Berrangé Signed-off-by: Richard Henderson Reviewed-by: Daniel P. Berrangé --- v3: If getrandom is not present, fall back on /dev/(u)random. --- crypto/random-platform.c | 37 ++++++++++++++++++++++++++++++++----- configure | 18 +++++++++++++++++- 2 files changed, 49 insertions(+), 6 deletions(-) diff --git a/crypto/random-platform.c b/crypto/random-platform.c index 6df40744c7..cb3ca1bc09 100644 --- a/crypto/random-platform.c +++ b/crypto/random-platform.c @@ -27,7 +27,11 @@ #include static HCRYPTPROV hCryptProv; #else -static int fd; /* a file handle to either /dev/urandom or /dev/random */ +# ifdef CONFIG_GETRANDOM +# include +# endif +/* This is -1 for getrandom(), or a file handle for /dev/{u,}random. */ +static int fd; #endif int qcrypto_random_init(Error **errp) @@ -40,15 +44,20 @@ int qcrypto_random_init(Error **errp) return -1; } #else - /* TBD perhaps also add support for BSD getentropy / Linux - * getrandom syscalls directly */ +# ifdef CONFIG_GETRANDOM + if (getrandom(NULL, 0, 0) == 0) { + /* Use getrandom() */ + fd = -1; + return 0; + } + /* Fall through to /dev/urandom case. */ +# endif fd = open("/dev/urandom", O_RDONLY | O_CLOEXEC); if (fd == -1 && errno == ENOENT) { fd = open("/dev/random", O_RDONLY | O_CLOEXEC); } - if (fd < 0) { - error_setg(errp, "No /dev/urandom or /dev/random found"); + error_setg_errno(errp, errno, "No /dev/urandom or /dev/random"); return -1; } #endif @@ -66,6 +75,24 @@ int qcrypto_random_bytes(uint8_t *buf G_GNUC_UNUSED, return -1; } #else +# ifdef CONFIG_GETRANDOM + if (likely(fd < 0)) { + while (1) { + ssize_t got = getrandom(buf, buflen, 0); + if (likely(got == buflen)) { + return 0; + } + if (got >= 0) { + buflen -= got; + buf += got; + } else if (errno != EINTR) { + error_setg_errno(errp, errno, "getrandom"); + return -1; + } + } + } + /* Fall through to /dev/urandom case. */ +# endif while (1) { ssize_t got = read(fd, buf, buflen); if (likely(got == buflen)) { diff --git a/configure b/configure index 2c95e6ddc9..2b79c2fad8 100755 --- a/configure +++ b/configure @@ -5781,6 +5781,20 @@ if compile_prog "" "" ; then have_utmpx=yes fi +########################################## +# check for getrandom() + +have_getrandom=no +cat > $TMPC << EOF +#include +int main(void) { + return getrandom(0, 0, GRND_NONBLOCK); +} +EOF +if compile_prog "" "" ; then + have_getrandom=yes +fi + ########################################## # checks for sanitizers @@ -7163,7 +7177,9 @@ fi if test "$have_utmpx" = "yes" ; then echo "HAVE_UTMPX=y" >> $config_host_mak fi - +if test "$have_getrandom" = "yes" ; then + echo "CONFIG_GETRANDOM=y" >> $config_host_mak +fi if test "$ivshmem" = "yes" ; then echo "CONFIG_IVSHMEM=y" >> $config_host_mak fi