From: Andy Lutomirski <luto@kernel.org>
To: Theodore Tso <tytso@google.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
Linux API <linux-api@vger.kernel.org>,
Kees Cook <keescook@chromium.org>,
"Jason A. Donenfeld" <Jason@zx2c4.com>,
"Ahmed S. Darwish" <darwish.07@gmail.com>,
Lennart Poettering <mzxreary@0pointer.de>,
"Eric W. Biederman" <ebiederm@xmission.com>,
"Alexander E. Patrakov" <patrakov@gmail.com>,
Michael Kerrisk <mtk.manpages@gmail.com>,
Willy Tarreau <w@1wt.eu>, Matthew Garrett <mjg59@srcf.ucam.org>,
Ext4 Developers List <linux-ext4@vger.kernel.org>,
linux-man <linux-man@vger.kernel.org>,
Andy Lutomirski <luto@kernel.org>
Subject: [PATCH v2 2/7] random: Add GRND_INSECURE to return best-effort non-cryptographic bytes
Date: Fri, 20 Sep 2019 07:36:24 -0700 [thread overview]
Message-ID: <f38025d4ade72489cbf0faa887f8d850cad3846b.1568990048.git.luto@kernel.org> (raw)
In-Reply-To: <cover.1568990048.git.luto@kernel.org>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
drivers/char/random.c | 11 +++++++++--
include/uapi/linux/random.h | 2 ++
2 files changed, 11 insertions(+), 2 deletions(-)
diff --git a/drivers/char/random.c b/drivers/char/random.c
index d152612e08fc..acabb870f222 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -2122,7 +2122,14 @@ SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count,
{
int ret;
- if (flags & ~(GRND_NONBLOCK|GRND_RANDOM))
+ if (flags & ~(GRND_NONBLOCK|GRND_RANDOM|GRND_INSECURE))
+ return -EINVAL;
+
+ /*
+ * Requesting insecure and blocking randomness at the same time makes
+ * no sense.
+ */
+ if ((flags & (GRND_INSECURE|GRND_RANDOM)) == (GRND_INSECURE|GRND_RANDOM))
return -EINVAL;
if (count > INT_MAX)
@@ -2131,7 +2138,7 @@ SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count,
if (flags & GRND_RANDOM)
return _random_read(flags & GRND_NONBLOCK, buf, count);
- if (!crng_ready()) {
+ if (!(flags & GRND_INSECURE) && !crng_ready()) {
if (flags & GRND_NONBLOCK)
return -EAGAIN;
ret = wait_for_random_bytes();
diff --git a/include/uapi/linux/random.h b/include/uapi/linux/random.h
index 26ee91300e3e..c092d20088d3 100644
--- a/include/uapi/linux/random.h
+++ b/include/uapi/linux/random.h
@@ -49,8 +49,10 @@ struct rand_pool_info {
*
* GRND_NONBLOCK Don't block and return EAGAIN instead
* GRND_RANDOM Use the /dev/random pool instead of /dev/urandom
+ * GRND_INSECURE Return non-cryptographic random bytes
*/
#define GRND_NONBLOCK 0x0001
#define GRND_RANDOM 0x0002
+#define GRND_INSECURE 0x0004
#endif /* _UAPI_LINUX_RANDOM_H */
--
2.21.0
next prev parent reply other threads:[~2019-09-20 14:37 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-20 14:36 [PATCH v2 0/7] Rework random blocking Andy Lutomirski
2019-09-20 14:36 ` [PATCH v2 1/7] random: Don't wake crng_init_wait when crng_init == 1 Andy Lutomirski
2019-09-20 14:36 ` Andy Lutomirski [this message]
2019-09-20 14:36 ` [PATCH v2 3/7] random: Ignore GRND_RANDOM in getentropy(2) Andy Lutomirski
2019-09-20 14:36 ` [PATCH v2 4/7] random: Make /dev/random be almost like /dev/urandom Andy Lutomirski
2019-09-20 14:36 ` [PATCH v2 5/7] random: Remove the blocking pool Andy Lutomirski
2019-09-20 14:36 ` [PATCH v2 6/7] random: Delete code to pull data into pools Andy Lutomirski
2019-09-20 14:36 ` [PATCH v2 7/7] random: Remove kernel.random.read_wakeup_threshold Andy Lutomirski
2019-09-24 20:30 ` Jann Horn
2019-09-26 1:09 ` Eric W. Biederman
2019-09-20 14:46 ` [PATCH v2 0/7] Rework random blocking Andy Lutomirski
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