linux/drivers/char
Linus Torvalds 8a0a9bd4db random: make get_random_int() more random
It's a really simple patch that basically just open-codes the current
"secure_ip_id()" call, but when open-coding it we now use a _static_
hashing area, so that it gets updated every time.

And to make sure somebody can't just start from the same original seed of
all-zeroes, and then do the "half_md4_transform()" over and over until
they get the same sequence as the kernel has, each iteration also mixes in
the same old "current->pid + jiffies" we used - so we should now have a
regular strong pseudo-number generator, but we also have one that doesn't
have a single seed.

Note: the "pid + jiffies" is just meant to be a tiny tiny bit of noise. It
has no real meaning. It could be anything. I just picked the previous
seed, it's just that now we keep the state in between calls and that will
feed into the next result, and that should make all the difference.

I made that hash be a per-cpu data just to avoid cache-line ping-pong:
having multiple CPU's write to the same data would be fine for randomness,
and add yet another layer of chaos to it, but since get_random_int() is
supposed to be a fast interface I did it that way instead. I considered
using "__raw_get_cpu_var()" to avoid any preemption overhead while still
getting the hash be _mostly_ ping-pong free, but in the end good taste won
out.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-05-07 11:59:06 -07:00
..
agp Merge branch 'drm-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6 2009-04-20 08:42:48 -07:00
hw_random virtio-rng: Remove false BUG for spurious callbacks 2009-04-24 13:28:30 -07:00
ip2 proc tty: switch ip2 to ->proc_fops 2009-04-01 08:59:08 -07:00
ipmi ipmi: add oem message handling 2009-04-21 13:41:48 -07:00
mwave mwave: struct device - replace bus_id with dev_name(), dev_set_name() 2009-01-06 10:44:38 -08:00
pcmcia proc tty: switch synclink_cs to ->proc_fops 2009-04-01 08:59:08 -07:00
rio rio: addition has higher precedence than ?: 2009-04-06 14:36:43 -07:00
tpm Merge git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core-2.6 2009-03-26 11:17:04 -07:00
xilinx_hwicap
.gitignore
amiserial.c proc tty: switch amiserial to ->proc_fops 2009-04-01 08:59:10 -07:00
apm-emulation.c
applicom.c applicom: Auto-load applicom module when device opened. 2009-04-06 14:36:30 -07:00
applicom.h
bfin-otp.c
briq_panel.c
bsr.c trivial: drivers/char/bsr.c: Storage class should be before const qualifier 2009-03-30 15:22:02 +02:00
cd1865.h
ChangeLog
consolemap.c consolemap: indentation & braces disagree - reindent 2009-01-06 15:59:30 -08:00
cp437.uni
cs5535_gpio.c
cyclades.c cyclades: Auto-load cyclades module when device opened. 2009-04-06 14:36:30 -07:00
defkeymap.c_shipped
defkeymap.map
digi1.h
digiFep1.h
digiPCI.h
ds1302.c
ds1620.c
dsp56k.c
dtlk.c
efirtc.c
epca.c trivial: fix an -> a typos in documentation and comments 2009-01-06 11:28:07 +01:00
epca.h
epcaconfig.h
esp.c esp: fix section mismatch warning 2009-04-07 08:31:03 -07:00
generic_nvram.c
generic_serial.c tty: Remove some pointless casts 2009-01-02 10:19:40 -08:00
genrtc.c
hangcheck-timer.c
hpet.c clocksource: pass clocksource to read() callback 2009-04-21 13:41:47 -07:00
hvc_beat.c powerpc/cell: Use correct types in beat files 2009-01-08 16:25:16 +11:00
hvc_console.c hvc_console: Remove tty->low_latency 2009-01-16 16:15:16 +11:00
hvc_console.h
hvc_irq.c hvc_console: Call free_irq() only if request_irq() was successful 2009-01-13 14:48:01 +11:00
hvc_iseries.c
hvc_iucv.c [S390] hvc_iucv: Provide IUCV z/VM user ID filtering 2009-03-26 15:24:08 +01:00
hvc_rtas.c
hvc_udbg.c
hvc_vio.c
hvc_xen.c
hvcs.c hvc_console: Remove tty->low_latency on pseries backends 2009-03-11 10:44:26 +11:00
hvsi.c hvc_console: Remove tty->low_latency on pseries backends 2009-03-11 10:44:26 +11:00
i8k.c i8k: Add Dell Vostro systems 2009-01-02 10:28:32 -08:00
isicom.c isicom: isicom kref leak fix 2009-04-06 14:36:33 -07:00
istallion.c proc tty: switch istallion to ->proc_fops 2009-04-01 08:59:08 -07:00
Kconfig NVRAM depends on RTC_DRV_CMOS 2009-01-31 01:21:59 +01:00
keyboard.c
lp.c
Makefile
mbcs.c
mbcs.h
mem.c x86, PAT: Remove duplicate memtype reserve in devmem mmap 2009-04-10 13:55:48 +02:00
misc.c
mmtimer.c
moxa.c tty: moxa, fix refcounting in moxa_poll_port 2009-04-06 14:36:33 -07:00
moxa.h
mspec.c
mxser.c mxser: remove tty_port_tty_get from mxser_check_modem_status 2009-04-06 14:36:33 -07:00
mxser.h
n_hdlc.c
n_r3964.c tty: Remove some pointless casts 2009-01-02 10:19:40 -08:00
n_tty.c tty: N_TTY SIGIO only works for read 2009-01-02 10:19:40 -08:00
nozomi.c tty: kref nozomi 2009-01-02 10:19:40 -08:00
nsc_gpio.c
nvram.c
nwbutton.c
nwbutton.h
nwflash.c
pc8736x_gpio.c
ppdev.c
ps3flash.c powerpc/ps3: Printing fixups for l64 to ll64 conversion drivers/char 2009-01-16 16:15:14 +11:00
pty.c pty: Fix documentation 2009-01-12 16:37:00 -08:00
random.c random: make get_random_int() more random 2009-05-07 11:59:06 -07:00
raw.c Add a missing unlock_kernel() in raw_open() 2009-03-27 10:59:09 -06:00
riscom8_reg.h
riscom8.c riscom8: Auto-load riscom8 module when device opened. 2009-04-06 14:36:31 -07:00
riscom8.h
rocket_int.h tty: rocketport uses different port flags to everyone else 2009-01-02 10:19:39 -08:00
rocket.c tty: use port methods for the rocket driver 2009-01-02 10:19:42 -08:00
rocket.h tty: rocketport uses different port flags to everyone else 2009-01-02 10:19:39 -08:00
rtc.c RTC: Remove the BKL. 2009-01-08 16:44:03 -07:00
scc.h m68k: atari - Rename "mfp" to "st_mfp" 2009-02-22 09:23:02 -08:00
scx200_gpio.c
selection.c Fix memory corruption in console selection 2009-01-31 15:51:31 -08:00
ser_a2232.c m68k: ser_a2232 - Kill warn_unused_result warnings 2009-01-12 20:56:39 +01:00
ser_a2232.h
ser_a2232fw.ax
ser_a2232fw.h
serial167.c tty: Remove some pointless casts 2009-01-02 10:19:40 -08:00
snsc_event.c
snsc.c
snsc.h
sonypi.c Rationalize fasync return values 2009-03-16 08:34:35 -06:00
specialix_io8.h
specialix.c specialix: Auto-load specialix module when device opened. 2009-04-06 14:36:31 -07:00
stallion.c proc tty: switch stallion to ->proc_fops 2009-04-01 08:59:09 -07:00
sx.c sx.c: avoid referencing freed memory if copy_from_user() fails 2009-02-20 17:57:49 -08:00
sx.h
sxboards.h
sxwindow.h
synclink_gt.c synclink_gt: add clock options 2009-04-02 19:05:01 -07:00
synclink.c proc tty: switch synclink to ->proc_fops 2009-04-01 08:59:09 -07:00
synclinkmp.c proc tty: switch synclinkmp to ->proc_fops 2009-04-01 08:59:09 -07:00
sysrq.c sysrq: remove duplicated #include 2009-04-13 15:04:31 -07:00
tb0219.c
tlclk.c
toshiba.c
tty_audit.c Trim includes of fdtable.h 2009-03-31 23:00:28 -04:00
tty_buffer.c
tty_io.c pids: kill signal_struct-> __pgrp/__session and friends 2009-04-02 19:05:02 -07:00
tty_ioctl.c tty: Fix race in the flush for some ldiscs 2009-01-15 12:48:35 -08:00
tty_ldisc.c Trim includes of fdtable.h 2009-03-31 23:00:28 -04:00
tty_port.c tty: use port methods for the rocket driver 2009-01-02 10:19:42 -08:00
vc_screen.c vcs: hook sysfs devices into object lifetime instead of "binding" 2009-03-24 16:38:26 -07:00
viotape.c
virtio_console.c
vme_scc.c m68k: vme_scc - Kill warn_unused_result warnings 2009-01-12 20:56:38 +01:00
vr41xx_giu.c
vt_ioctl.c vt: Add a note on the historical abuse of CLOCK_TICK_RATE 2009-05-06 14:47:13 -07:00
vt.c Revert "console ASCII glyph 1:1 mapping" 2009-04-19 10:51:40 -07:00