git: 06630432d826 - stable/12 - random(4): Add is_random_seeded(9) KPI
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Date: Sun, 13 Feb 2022 07:29:46 UTC
The branch stable/12 has been updated by obrien:
URL: https://cgit.FreeBSD.org/src/commit/?id=06630432d8260d6eba9277c6498ec769fc41f02a
commit 06630432d8260d6eba9277c6498ec769fc41f02a
Author: Conrad Meyer <cem@FreeBSD.org>
AuthorDate: 2019-04-16 17:12:17 +0000
Commit: David E. O'Brien <obrien@FreeBSD.org>
CommitDate: 2022-02-13 06:34:38 +0000
random(4): Add is_random_seeded(9) KPI
The imagined use is for early boot consumers of random to be able to make
decisions based on whether random is available yet or not. One such
consumer seems to be __stack_chk_init(), which runs immediately after random
is initialized. A follow-up patch will attempt to address that.
(cherry picked from commit f3d2512db6ec23985b10fbcbe0b3bd34ea2574df)
---
UPDATING | 6 ++++++
share/man/man9/Makefile | 1 +
share/man/man9/random.9 | 12 +++++++++++-
sys/dev/random/random_infra.c | 23 ++++++++++++++++++++++-
sys/dev/random/randomdev.c | 11 ++++++++++-
sys/dev/random/randomdev.h | 3 ++-
sys/sys/random.h | 6 ++++++
7 files changed, 58 insertions(+), 4 deletions(-)
diff --git a/UPDATING b/UPDATING
index e0e5c3b1f8ef..031d73d7e150 100644
--- a/UPDATING
+++ b/UPDATING
@@ -17,6 +17,12 @@ from older versions of FreeBSD, try WITHOUT_CLANG and WITH_GCC to bootstrap to
the tip of head, and then rebuild without this option. The bootstrap process
from older version of current across the gcc/clang cutover is a bit fragile.
+20220214:
+ The loadable random module KPI has changed; the random_infra_init()
+ routine now requires a 3rd function pointer for a bool (*)(void)
+ method that returns true if the random device is seeded (and
+ therefore unblocked).
+
20211214:
Clang, llvm, lld, lldb, compiler-rt, libc++, libunwind and openmp have
been upgraded to 11.0.0. Please see the 20141231 entry below for
diff --git a/share/man/man9/Makefile b/share/man/man9/Makefile
index 3dc97428713e..5f6cefc09329 100644
--- a/share/man/man9/Makefile
+++ b/share/man/man9/Makefile
@@ -1698,6 +1698,7 @@ MLINKS+=psignal.9 gsignal.9 \
MLINKS+=pwmbus.9 pwm.9
MLINKS+=random.9 arc4rand.9 \
random.9 arc4random.9 \
+ random.9 is_random_seeded.9 \
random.9 read_random.9 \
random.9 read_random_uio.9 \
random.9 srandom.9
diff --git a/share/man/man9/random.9 b/share/man/man9/random.9
index 2e6189790412..97218dcab39c 100644
--- a/share/man/man9/random.9
+++ b/share/man/man9/random.9
@@ -26,13 +26,14 @@
.\"
.\" $FreeBSD$
.\" "
-.Dd April 15, 2019
+.Dd April 16, 2019
.Dt RANDOM 9
.Os
.Sh NAME
.Nm arc4rand ,
.Nm arc4random ,
.Nm arc4random_buf ,
+.Nm is_random_seeded ,
.Nm random ,
.Nm read_random ,
.Nm read_random_uio ,
@@ -48,6 +49,8 @@
.Fn arc4rand "void *ptr" "u_int length" "int reseed"
.Pp
.In sys/random.h
+.Ft bool
+.Fn is_random_seeded "void"
.Ft void
.Fn read_random "void *buffer" "int count"
.Ft int
@@ -108,6 +111,13 @@ instead, use the
family of functions.
.Pp
The
+.Fn is_random_seeded
+function can be used to check in advance if
+.Fn read_random
+will block.
+(If random is seeded, it will not block.)
+.Pp
+The
.Fn read_random_uio
function behaves identically to
.Xr read 2
diff --git a/sys/dev/random/random_infra.c b/sys/dev/random/random_infra.c
index 324c40dcecd4..59cd44280b95 100644
--- a/sys/dev/random/random_infra.c
+++ b/sys/dev/random/random_infra.c
@@ -63,12 +63,20 @@ null_read_random(void *dummy __unused, u_int dummy2 __unused)
panic("%s: no random module is loaded", __func__);
}
+static bool
+null_is_random_seeded(void)
+{
+ return (false);
+}
+
struct random_readers {
int (*read_random_uio)(struct uio *, bool);
void (*read_random)(void *, u_int);
+ bool (*is_random_seeded)(void);
} random_reader_context = {
(int (*)(struct uio *, bool))nullop,
null_read_random,
+ null_is_random_seeded,
};
struct sx randomdev_config_lock;
@@ -82,12 +90,15 @@ random_infra_sysinit(void *dummy __unused)
SYSINIT(random_device_h_init, SI_SUB_RANDOM, SI_ORDER_FIRST, random_infra_sysinit, NULL);
void
-random_infra_init(int (*p_random_read_uio)(struct uio *, bool), void (*p_random_read)(void *, u_int))
+random_infra_init(int (*p_random_read_uio)(struct uio *, bool),
+ void (*p_random_read)(void *, u_int),
+ bool (*p_is_random_seeded)(void))
{
RANDOM_CONFIG_X_LOCK();
random_reader_context.read_random_uio = p_random_read_uio;
random_reader_context.read_random = p_random_read;
+ random_reader_context.is_random_seeded = p_is_random_seeded;
RANDOM_CONFIG_X_UNLOCK();
}
@@ -98,6 +109,7 @@ random_infra_uninit(void)
RANDOM_CONFIG_X_LOCK();
random_reader_context.read_random_uio = (int (*)(struct uio *, bool))nullop;
random_reader_context.read_random = null_read_random;
+ random_reader_context.is_random_seeded = null_is_random_seeded;
RANDOM_CONFIG_X_UNLOCK();
}
@@ -129,4 +141,13 @@ read_random(void *buf, u_int len)
RANDOM_CONFIG_S_UNLOCK();
}
+bool
+is_random_seeded(void)
+{
+ RANDOM_CONFIG_S_LOCK();
+ random_reader_context.is_random_seeded();
+ RANDOM_CONFIG_S_UNLOCK();
+}
+
+
#endif /* defined(RANDOM_LOADABLE) */
diff --git a/sys/dev/random/randomdev.c b/sys/dev/random/randomdev.c
index 19a73b28151a..cbe01d1c5343 100644
--- a/sys/dev/random/randomdev.c
+++ b/sys/dev/random/randomdev.c
@@ -62,11 +62,14 @@ __FBSDID("$FreeBSD$");
#if defined(RANDOM_LOADABLE)
#define READ_RANDOM_UIO _read_random_uio
#define READ_RANDOM _read_random
+#define IS_RANDOM_SEEDED _is_random_seeded
static int READ_RANDOM_UIO(struct uio *, bool);
static void READ_RANDOM(void *, u_int);
+static bool IS_RANDOM_SEEDED(void);
#else
#define READ_RANDOM_UIO read_random_uio
#define READ_RANDOM read_random
+#define IS_RANDOM_SEEDED is_random_seeded
#endif
static d_read_t randomdev_read;
@@ -93,7 +96,7 @@ random_alg_context_ra_init_alg(void *data)
p_random_alg_context = &random_alg_context;
p_random_alg_context->ra_init_alg(data);
#if defined(RANDOM_LOADABLE)
- random_infra_init(READ_RANDOM_UIO, READ_RANDOM);
+ random_infra_init(READ_RANDOM_UIO, READ_RANDOM, IS_RANDOM_SEEDED);
#endif
}
@@ -271,6 +274,12 @@ READ_RANDOM(void *random_buf, u_int len)
}
}
+bool
+IS_RANDOM_SEEDED(void)
+{
+ return (p_random_alg_context->ra_seeded());
+}
+
static __inline void
randomdev_accumulate(uint8_t *buf, u_int count)
{
diff --git a/sys/dev/random/randomdev.h b/sys/dev/random/randomdev.h
index 41300f237aaf..e5df7efefa5b 100644
--- a/sys/dev/random/randomdev.h
+++ b/sys/dev/random/randomdev.h
@@ -118,7 +118,8 @@ extern struct sx randomdev_config_lock;
#define RANDOM_CONFIG_S_LOCK(x) sx_slock(&randomdev_config_lock)
#define RANDOM_CONFIG_S_UNLOCK(x) sx_sunlock(&randomdev_config_lock)
#define RANDOM_CONFIG_DEINIT_LOCK(x) sx_destroy(&randomdev_config_lock)
-void random_infra_init(int (*)(struct uio *, bool), void (*)(void *, u_int));
+void random_infra_init(int (*)(struct uio *, bool), void (*)(void *, u_int),
+ bool (*)(void));
void random_infra_uninit(void);
#endif
diff --git a/sys/sys/random.h b/sys/sys/random.h
index f64728e79b8d..43b7c2640d14 100644
--- a/sys/sys/random.h
+++ b/sys/sys/random.h
@@ -40,6 +40,7 @@ struct uio;
#if defined(DEV_RANDOM)
void read_random(void *, u_int);
int read_random_uio(struct uio *, bool);
+bool is_random_seeded(void);
#else
static __inline int
read_random_uio(void *a __unused, u_int b __unused)
@@ -50,6 +51,11 @@ static __inline void
read_random(void *a __unused, u_int b __unused)
{
}
+static __inline bool
+is_random_seeded(void)
+{
+ return (false);
+}
#endif
/*