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authorLinus Torvalds <torvalds@linux-foundation.org>2022-08-03 03:31:35 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2022-08-03 03:31:35 +0300
commita0b09f2d6f30723e1008bd9ddb504e302e329f81 (patch)
tree373004df20337e2f9292feb00b1751453dafa758 /arch/um
parent569bede0cff5e98c0f862d486406b79dcada8eea (diff)
parent7f637be4d46029bd7700c9f244945a42dbd976fa (diff)
downloadlinux-a0b09f2d6f30723e1008bd9ddb504e302e329f81.tar.xz
Merge tag 'random-6.0-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random
Pull random number generator updates from Jason Donenfeld: "Though there's been a decent amount of RNG-related development during this last cycle, not all of it is coming through this tree, as this cycle saw a shift toward tackling early boot time seeding issues, which took place in other trees as well. Here's a summary of the various patches: - The CONFIG_ARCH_RANDOM .config option and the "nordrand" boot option have been removed, as they overlapped with the more widely supported and more sensible options, CONFIG_RANDOM_TRUST_CPU and "random.trust_cpu". This change allowed simplifying a bit of arch code. - x86's RDRAND boot time test has been made a bit more robust, with RDRAND disabled if it's clearly producing bogus results. This would be a tip.git commit, technically, but I took it through random.git to avoid a large merge conflict. - The RNG has long since mixed in a timestamp very early in boot, on the premise that a computer that does the same things, but does so starting at different points in wall time, could be made to still produce a different RNG state. Unfortunately, the clock isn't set early in boot on all systems, so now we mix in that timestamp when the time is actually set. - User Mode Linux now uses the host OS's getrandom() syscall to generate a bootloader RNG seed and later on treats getrandom() as the platform's RDRAND-like faculty. - The arch_get_random_{seed_,}_long() family of functions is now arch_get_random_{seed_,}_longs(), which enables certain platforms, such as s390, to exploit considerable performance advantages from requesting multiple CPU random numbers at once, while at the same time compiling down to the same code as before on platforms like x86. - A small cleanup changing a cmpxchg() into a try_cmpxchg(), from Uros. - A comment spelling fix" More info about other random number changes that come in through various architecture trees in the full commentary in the pull request: https://lore.kernel.org/all/20220731232428.2219258-1-Jason@zx2c4.com/ * tag 'random-6.0-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random: random: correct spelling of "overwrites" random: handle archrandom with multiple longs um: seed rng using host OS rng random: use try_cmpxchg in _credit_init_bits timekeeping: contribute wall clock to rng on time change x86/rdrand: Remove "nordrand" flag in favor of "random.trust_cpu" random: remove CONFIG_ARCH_RANDOM
Diffstat (limited to 'arch/um')
-rw-r--r--arch/um/include/asm/archrandom.h25
-rw-r--r--arch/um/include/shared/os.h7
-rw-r--r--arch/um/kernel/um_arch.c8
-rw-r--r--arch/um/os-Linux/util.c6
4 files changed, 46 insertions, 0 deletions
diff --git a/arch/um/include/asm/archrandom.h b/arch/um/include/asm/archrandom.h
new file mode 100644
index 000000000000..24e16c979c51
--- /dev/null
+++ b/arch/um/include/asm/archrandom.h
@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_UM_ARCHRANDOM_H__
+#define __ASM_UM_ARCHRANDOM_H__
+
+#include <linux/types.h>
+
+/* This is from <os.h>, but better not to #include that in a global header here. */
+ssize_t os_getrandom(void *buf, size_t len, unsigned int flags);
+
+static inline size_t __must_check arch_get_random_longs(unsigned long *v, size_t max_longs)
+{
+ ssize_t ret;
+
+ ret = os_getrandom(v, max_longs * sizeof(*v), 0);
+ if (ret < 0)
+ return 0;
+ return ret / sizeof(*v);
+}
+
+static inline size_t __must_check arch_get_random_seed_longs(unsigned long *v, size_t max_longs)
+{
+ return 0;
+}
+
+#endif
diff --git a/arch/um/include/shared/os.h b/arch/um/include/shared/os.h
index fafde1d5416e..0df646c6651e 100644
--- a/arch/um/include/shared/os.h
+++ b/arch/um/include/shared/os.h
@@ -11,6 +11,12 @@
#include <irq_user.h>
#include <longjmp.h>
#include <mm_id.h>
+/* This is to get size_t */
+#ifndef __UM_HOST__
+#include <linux/types.h>
+#else
+#include <sys/types.h>
+#endif
#define CATCH_EINTR(expr) while ((errno = 0, ((expr) < 0)) && (errno == EINTR))
@@ -243,6 +249,7 @@ extern void stack_protections(unsigned long address);
extern int raw(int fd);
extern void setup_machinename(char *machine_out);
extern void setup_hostinfo(char *buf, int len);
+extern ssize_t os_getrandom(void *buf, size_t len, unsigned int flags);
extern void os_dump_core(void) __attribute__ ((noreturn));
extern void um_early_printk(const char *s, unsigned int n);
extern void os_fix_helper_signals(void);
diff --git a/arch/um/kernel/um_arch.c b/arch/um/kernel/um_arch.c
index 9838967d0b2f..e0de60e503b9 100644
--- a/arch/um/kernel/um_arch.c
+++ b/arch/um/kernel/um_arch.c
@@ -16,6 +16,7 @@
#include <linux/sched/task.h>
#include <linux/kmsg_dump.h>
#include <linux/suspend.h>
+#include <linux/random.h>
#include <asm/processor.h>
#include <asm/cpufeature.h>
@@ -406,6 +407,8 @@ int __init __weak read_initrd(void)
void __init setup_arch(char **cmdline_p)
{
+ u8 rng_seed[32];
+
stack_protections((unsigned long) &init_thread_info);
setup_physmem(uml_physmem, uml_reserved, physmem_size, highmem);
mem_total_pages(physmem_size, iomem_size, highmem);
@@ -416,6 +419,11 @@ void __init setup_arch(char **cmdline_p)
strlcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
*cmdline_p = command_line;
setup_hostinfo(host_info, sizeof host_info);
+
+ if (os_getrandom(rng_seed, sizeof(rng_seed), 0) == sizeof(rng_seed)) {
+ add_bootloader_randomness(rng_seed, sizeof(rng_seed));
+ memzero_explicit(rng_seed, sizeof(rng_seed));
+ }
}
void __init check_bugs(void)
diff --git a/arch/um/os-Linux/util.c b/arch/um/os-Linux/util.c
index 41297ec404bf..fc0f2a9dee5a 100644
--- a/arch/um/os-Linux/util.c
+++ b/arch/um/os-Linux/util.c
@@ -14,6 +14,7 @@
#include <sys/wait.h>
#include <sys/mman.h>
#include <sys/utsname.h>
+#include <sys/random.h>
#include <init.h>
#include <os.h>
@@ -96,6 +97,11 @@ static inline void __attribute__ ((noreturn)) uml_abort(void)
exit(127);
}
+ssize_t os_getrandom(void *buf, size_t len, unsigned int flags)
+{
+ return getrandom(buf, len, flags);
+}
+
/*
* UML helper threads must not handle SIGWINCH/INT/TERM
*/