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From: Dan Gora <dg@adax.com>
To: dev@dpdk.org, Mattias Rönnblom <mattias.ronnblom@ericsson.com>
Cc: David Marchand <david.marchand@redhat.com>,
	Jerin Jacob <jerinjacobk@gmail.com>, Dan Gora <dg@adax.com>
Subject: [dpdk-dev] [PATCH v3 2/2] eal: resolve getentropy at run time for random seed
Date: Wed, 22 Apr 2020 15:15:24 -0300
Message-ID: <20200422181524.18679-3-dg@adax.com> (raw)
In-Reply-To: <20200422181524.18679-1-dg@adax.com>

The getentropy() function was introduced into glibc v2.25 and so is
not available on all supported platforms.  Previously, if DPDK was
compiled (using meson) on a system which has getentropy(), it would
introduce a dependency on glibc v2.25 which would prevent that binary
from running on a system with an older glibc.  Similarly if DPDK was
compiled on a system which did not have getentropy(), getentropy()
could not be used even if the execution system supported it.

Introduce a new static function, __rte_getentropy() which will try to
resolve the getentropy() function dynamically using dlopen()/dlsym(),
returning failure if the getentropy() function cannot be resolved or
if it fails.

This also allows getentropy() to be used as the random seed source
when the traditional Makefile build for DPDK is used.

Signed-off-by: Dan Gora <dg@adax.com>
---
 lib/librte_eal/common/rte_random.c | 36 +++++++++++++++++++++++++-----
 lib/librte_eal/meson.build         |  3 ---
 2 files changed, 30 insertions(+), 9 deletions(-)

diff --git a/lib/librte_eal/common/rte_random.c b/lib/librte_eal/common/rte_random.c
index 2c84c8527..f8036aa20 100644
--- a/lib/librte_eal/common/rte_random.c
+++ b/lib/librte_eal/common/rte_random.c
@@ -7,6 +7,7 @@
 #endif
 #include <stdlib.h>
 #include <unistd.h>
+#include <dlfcn.h>
 
 #include <rte_branch_prediction.h>
 #include <rte_cycles.h>
@@ -176,18 +177,41 @@ rte_rand_max(uint64_t upper_bound)
 	return res;
 }
 
+/* Try to use the getentropy() function from glibc >= 2.25 */
+static int
+__rte_getentropy(uint64_t *ge_seed)
+{
+	void *handle = NULL;
+	void **sym;
+	int (*getentropy_p)(void *__buffer, size_t __length);
+	int gc_rc;
+
+	handle = dlopen("libc.so.6", RTLD_LAZY);
+	if (handle == NULL)
+		return -1;
+
+	dlerror();
+	sym = dlsym(handle, "getentropy");
+	if (dlerror() != NULL) {
+		/* Cannot resolve getentropy */
+		dlclose(handle);
+		return -1;
+	}
+
+	getentropy_p = (int (*)(void *, size_t)) sym;
+	gc_rc = (*getentropy_p)((void *)ge_seed, sizeof(*ge_seed));
+	dlclose(handle);
+	return gc_rc;
+}
+
 static uint64_t
 __rte_random_initial_seed(void)
 {
-#ifdef RTE_LIBEAL_USE_GETENTROPY
-	int ge_rc;
 	uint64_t ge_seed;
 
-	ge_rc = getentropy(&ge_seed, sizeof(ge_seed));
-
-	if (ge_rc == 0)
+	if (__rte_getentropy(&ge_seed) == 0)
 		return ge_seed;
-#endif
+
 #if defined(RTE_ARCH_X86)
 	/* first fallback: rdseed instruction, if available */
 	if (rte_cpu_get_flag_enabled(RTE_CPUFLAG_RDSEED)) {
diff --git a/lib/librte_eal/meson.build b/lib/librte_eal/meson.build
index 0267c3b9d..748359b8c 100644
--- a/lib/librte_eal/meson.build
+++ b/lib/librte_eal/meson.build
@@ -15,9 +15,6 @@ deps += 'kvargs'
 if dpdk_conf.has('RTE_USE_LIBBSD')
 	ext_deps += libbsd
 endif
-if cc.has_function('getentropy', prefix : '#include <unistd.h>')
-	cflags += '-DRTE_LIBEAL_USE_GETENTROPY'
-endif
 if cc.has_header('getopt.h')
 	cflags += ['-DHAVE_GETOPT_H', '-DHAVE_GETOPT', '-DHAVE_GETOPT_LONG']
 endif
-- 
2.24.1.425.g7034cd094b


  parent reply	other threads:[~2020-04-22 18:16 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-21 19:54 [dpdk-dev] [PATCH 0/2] eal: choose initial PRNG seed source at runtime Dan Gora
2020-04-21 19:54 ` [dpdk-dev] [PATCH 1/2] eal: check for rdseed at run time for random seed Dan Gora
2020-04-22  8:22   ` Mattias Rönnblom
2020-04-21 19:54 ` [dpdk-dev] [PATCH 2/2] eal: resolve getentropy " Dan Gora
2020-04-21 21:03   ` Stephen Hemminger
2020-04-21 21:08     ` Dan Gora
2020-04-22  8:28   ` Mattias Rönnblom
2020-04-22 17:44     ` Dan Gora
2020-04-22 20:14       ` Mattias Rönnblom
2020-04-22 20:35         ` Dan Gora
2020-04-23 10:04           ` Luca Boccassi
2020-04-23 17:38             ` Dan Gora
2020-04-27 12:44               ` Luca Boccassi
2020-04-27 16:57                 ` Dan Gora
2020-04-30  8:41                   ` Luca Boccassi
2020-04-30 20:43                     ` Dan Gora
2020-05-01 10:33                       ` Luca Boccassi
2020-05-01 21:05                         ` Dan Gora
2020-05-04  8:04                           ` Mattias Rönnblom
2020-05-04 14:13                             ` Dan Gora
2020-05-04 14:19                               ` Dan Gora
2020-06-02  5:10                                 ` Dan Gora
2020-06-09 15:37                                   ` Dan Gora
2020-06-10  8:15                                     ` Thomas Monjalon
2020-06-10  8:33                                       ` Luca Boccassi
2020-06-10  8:07                               ` Thomas Monjalon
2020-04-23 12:36           ` Mattias Rönnblom
2020-04-23 17:27             ` Dan Gora
2020-04-21 20:41 ` [dpdk-dev] [PATCH v2 0/2] eal: choose initial PRNG seed source at runtime Dan Gora
2020-04-21 20:41   ` [dpdk-dev] [PATCH v2 1/2] eal: check for rdseed at run time for random seed Dan Gora
2020-04-21 20:41   ` [dpdk-dev] [PATCH v2 2/2] eal: resolve getentropy " Dan Gora
2020-04-22 18:15 ` [dpdk-dev] [PATCH v3 0/2] eal: choose initial PRNG seed source at runtime Dan Gora
2020-04-22 18:15   ` [dpdk-dev] [PATCH v3 1/2] eal: check for rdseed at run time for random seed Dan Gora
2020-04-22 18:15   ` Dan Gora [this message]
2020-04-22 23:42 ` [dpdk-dev] [PATCH v4 0/2] eal: choose initial PRNG seed source at runtime Dan Gora
2020-04-22 23:42   ` [dpdk-dev] [PATCH v4 1/2] eal: check for rdseed at run time for random seed Dan Gora
2020-04-22 23:42   ` [dpdk-dev] [PATCH v4 2/2] eal: emulate glibc getentropy for initial " Dan Gora
2020-04-23  2:39     ` Stephen Hemminger
2020-04-23 17:42       ` Dan Gora
2020-06-29  9:30     ` Mattias Rönnblom
2020-06-29 17:57       ` Dan Gora
2020-06-29 20:57         ` Mattias Rönnblom
2020-06-29  9:32   ` [dpdk-dev] [PATCH v4 0/2] eal: choose initial PRNG seed source at runtime Mattias Rönnblom
2020-06-29 18:01     ` Dan Gora
2020-06-29 18:04       ` Dan Gora
2020-06-29 21:05       ` Mattias Rönnblom
2020-06-29 21:14         ` Dan Gora

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