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crypto: Use getrandom for qcrypto_random_bytes

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Prefer it to direct use of /dev/urandom.

Reviewed-by: Laurent Vivier <lvivier@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2019-03-13 20:57:28 -07:00
parent e9979ca64e
commit db1ed1abcf
2 changed files with 49 additions and 6 deletions
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37
crypto/random-platform.c
View file

@ -27,7 +27,11 @@
#include <wincrypt.h>
static HCRYPTPROV hCryptProv;
#else
static int fd; /* a file handle to either /dev/urandom or /dev/random */
# ifdef CONFIG_GETRANDOM
# include <sys/random.h>
# 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)) {