From 00044f17afd36bf6397b9a2a12f242a057449e9a Mon Sep 17 00:00:00 2001 From: Christian Lamparter Date: Mon, 15 Aug 2011 20:09:54 +0200 Subject: [PATCH] carl9170: export HW random number generator All AR9170 hardware have a 16-Bit random number generator. The documentation claims the values are suitable for "security keys". The "throughput" is around 320Kibit/s. It's slow, but it does work without introducing any special offload firmware commands. Signed-off-by: Christian Lamparter Signed-off-by: John W. Linville --- drivers/net/wireless/ath/carl9170/Kconfig | 14 +++ drivers/net/wireless/ath/carl9170/carl9170.h | 12 ++ drivers/net/wireless/ath/carl9170/main.c | 113 +++++++++++++++++++ 3 files changed, 139 insertions(+) diff --git a/drivers/net/wireless/ath/carl9170/Kconfig b/drivers/net/wireless/ath/carl9170/Kconfig index 2d1b821b440..267d5dcf82d 100644 --- a/drivers/net/wireless/ath/carl9170/Kconfig +++ b/drivers/net/wireless/ath/carl9170/Kconfig @@ -39,3 +39,17 @@ config CARL9170_WPC bool depends on CARL9170 && (INPUT = y || INPUT = CARL9170) default y + +config CARL9170_HWRNG + bool "Random number generator" + depends on CARL9170 && (HW_RANDOM = y || HW_RANDOM = CARL9170) + default n + help + Provides a hardware random number generator to the kernel. + + SECURITY WARNING: It's relatively easy to eavesdrop all + generated random numbers from the transport stream with + usbmon [software] or special usb sniffer hardware. + + Say N, unless your setup[i.e.: embedded system] has no + other rng source and you can afford to take the risk. diff --git a/drivers/net/wireless/ath/carl9170/carl9170.h b/drivers/net/wireless/ath/carl9170/carl9170.h index 74350d63f68..6cfbb419e2f 100644 --- a/drivers/net/wireless/ath/carl9170/carl9170.h +++ b/drivers/net/wireless/ath/carl9170/carl9170.h @@ -43,6 +43,7 @@ #include #include #include +#include #include #include #include @@ -449,6 +450,17 @@ struct ar9170 { unsigned int off_override; bool state; } ps; + +#ifdef CONFIG_CARL9170_HWRNG +# define CARL9170_HWRNG_CACHE_SIZE CARL9170_MAX_CMD_PAYLOAD_LEN + struct { + struct hwrng rng; + bool initialized; + char name[30 + 1]; + u16 cache[CARL9170_HWRNG_CACHE_SIZE / sizeof(u16)]; + unsigned int cache_idx; + } rng; +#endif /* CONFIG_CARL9170_HWRNG */ }; enum carl9170_ps_off_override_reasons { diff --git a/drivers/net/wireless/ath/carl9170/main.c b/drivers/net/wireless/ath/carl9170/main.c index 85cb1bdebaa..782b8f3ae58 100644 --- a/drivers/net/wireless/ath/carl9170/main.c +++ b/drivers/net/wireless/ath/carl9170/main.c @@ -1468,6 +1468,109 @@ static int carl9170_register_wps_button(struct ar9170 *ar) } #endif /* CONFIG_CARL9170_WPC */ +#ifdef CONFIG_CARL9170_HWRNG +static int carl9170_rng_get(struct ar9170 *ar) +{ + +#define RW (CARL9170_MAX_CMD_PAYLOAD_LEN / sizeof(u32)) +#define RB (CARL9170_MAX_CMD_PAYLOAD_LEN) + + static const __le32 rng_load[RW] = { + [0 ... (RW - 1)] = cpu_to_le32(AR9170_RAND_REG_NUM)}; + + u32 buf[RW]; + + unsigned int i, off = 0, transfer, count; + int err; + + BUILD_BUG_ON(RB > CARL9170_MAX_CMD_PAYLOAD_LEN); + + if (!IS_ACCEPTING_CMD(ar) || !ar->rng.initialized) + return -EAGAIN; + + count = ARRAY_SIZE(ar->rng.cache); + while (count) { + err = carl9170_exec_cmd(ar, CARL9170_CMD_RREG, + RB, (u8 *) rng_load, + RB, (u8 *) buf); + if (err) + return err; + + transfer = min_t(unsigned int, count, RW); + for (i = 0; i < transfer; i++) + ar->rng.cache[off + i] = buf[i]; + + off += transfer; + count -= transfer; + } + + ar->rng.cache_idx = 0; + +#undef RW +#undef RB + return 0; +} + +static int carl9170_rng_read(struct hwrng *rng, u32 *data) +{ + struct ar9170 *ar = (struct ar9170 *)rng->priv; + int ret = -EIO; + + mutex_lock(&ar->mutex); + if (ar->rng.cache_idx >= ARRAY_SIZE(ar->rng.cache)) { + ret = carl9170_rng_get(ar); + if (ret) { + mutex_unlock(&ar->mutex); + return ret; + } + } + + *data = ar->rng.cache[ar->rng.cache_idx++]; + mutex_unlock(&ar->mutex); + + return sizeof(u16); +} + +static void carl9170_unregister_hwrng(struct ar9170 *ar) +{ + if (ar->rng.initialized) { + hwrng_unregister(&ar->rng.rng); + ar->rng.initialized = false; + } +} + +static int carl9170_register_hwrng(struct ar9170 *ar) +{ + int err; + + snprintf(ar->rng.name, ARRAY_SIZE(ar->rng.name), + "%s_%s", KBUILD_MODNAME, wiphy_name(ar->hw->wiphy)); + ar->rng.rng.name = ar->rng.name; + ar->rng.rng.data_read = carl9170_rng_read; + ar->rng.rng.priv = (unsigned long)ar; + + if (WARN_ON(ar->rng.initialized)) + return -EALREADY; + + err = hwrng_register(&ar->rng.rng); + if (err) { + dev_err(&ar->udev->dev, "Failed to register the random " + "number generator (%d)\n", err); + return err; + } + + ar->rng.initialized = true; + + err = carl9170_rng_get(ar); + if (err) { + carl9170_unregister_hwrng(ar); + return err; + } + + return 0; +} +#endif /* CONFIG_CARL9170_HWRNG */ + static int carl9170_op_get_survey(struct ieee80211_hw *hw, int idx, struct survey_info *survey) { @@ -1878,6 +1981,12 @@ int carl9170_register(struct ar9170 *ar) goto err_unreg; #endif /* CONFIG_CARL9170_WPC */ +#ifdef CONFIG_CARL9170_HWRNG + err = carl9170_register_hwrng(ar); + if (err) + goto err_unreg; +#endif /* CONFIG_CARL9170_HWRNG */ + dev_info(&ar->udev->dev, "Atheros AR9170 is registered as '%s'\n", wiphy_name(ar->hw->wiphy)); @@ -1910,6 +2019,10 @@ void carl9170_unregister(struct ar9170 *ar) } #endif /* CONFIG_CARL9170_WPC */ +#ifdef CONFIG_CARL9170_HWRNG + carl9170_unregister_hwrng(ar); +#endif /* CONFIG_CARL9170_HWRNG */ + carl9170_cancel_worker(ar); cancel_work_sync(&ar->restart_work); -- 2.39.2