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[178.24.244.248]) by smtp.gmail.com with ESMTPSA id u8sm50023wmj.27.2019.04.26.14.55.51 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Fri, 26 Apr 2019 14:55:52 -0700 (PDT) From: Eugeniu Rosca X-Google-Original-From: Eugeniu Rosca To: Marek Vasut , Simon Glass , Masahiro Yamada , Lukasz Majewski , u-boot@lists.denx.de Date: Fri, 26 Apr 2019 23:54:58 +0200 Message-Id: <20190426215458.5057-1-erosca@de.adit-jv.com> X-Mailer: git-send-email 2.21.0 MIME-Version: 1.0 Cc: Eugeniu Rosca , Eugeniu Rosca Subject: [U-Boot] [PATCH] lib: uuid: Improve randomness of uuid values on RANDOM_UUID=y X-BeenThere: u-boot@lists.denx.de X-Mailman-Version: 2.1.18 Precedence: list List-Id: U-Boot discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: u-boot-bounces@lists.denx.de Sender: "U-Boot" The random uuid values (enabled via CONFIG_RANDOM_UUID=y) on our platform are always the same. Below is consistent on each cold boot: => ### reach U-Boot prompt => setenv uuid_gpt_misc => gpt verify mmc 1 $partitions Verify GPT: success! => print uuid_gpt_misc uuid_gpt_misc=d117f98e-6f2c-d04b-a5b2-331a19f91cb2 => setenv uuid_gpt_misc => gpt verify mmc 1 $partitions Verify GPT: success! => print uuid_gpt_misc uuid_gpt_misc=ad5ec4b6-2d9f-8544-9417-fe3bd1c9b1b3 While the uuids do change on every 'gpt {write,verify}' command, the values appear to be taken from the same pool, in the same order. As a user, I expect a trully random uuid value in the above example. Otherwise, system/RFS designers and OS people might assume they have a reliable/consistent uuid passed by the bootloader, while the truth is U-Boot simply lacks entropy to generate a random string. Let's use get_timer() to update the seed, same as done in commit da384a9d7628 ("net: rename and refactor eth_rand_ethaddr() function"). Signed-off-by: Eugeniu Rosca Reviewed-by: Lukasz Majewski --- lib/uuid.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/lib/uuid.c b/lib/uuid.c index fa20ee39fc32..8a82cb234b88 100644 --- a/lib/uuid.c +++ b/lib/uuid.c @@ -238,6 +238,8 @@ void gen_rand_uuid(unsigned char *uuid_bin) unsigned int *ptr = (unsigned int *)&uuid; int i; + srand(get_timer(0)); + /* Set all fields randomly */ for (i = 0; i < sizeof(struct uuid) / sizeof(*ptr); i++) *(ptr + i) = cpu_to_be32(rand());