From: Benjamin Gray <bgray@linux.ibm.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: ajd@linux.ibm.com, linux-kernel@vger.kernel.org,
linux-hardening@vger.kernel.org, cmr@bluescreens.de,
Benjamin Gray <bgray@linux.ibm.com>
Subject: [RFC PATCH 04/13] powerpc/dexcr: Support userspace ROP protection
Date: Mon, 28 Nov 2022 13:44:49 +1100 [thread overview]
Message-ID: <20221128024458.46121-5-bgray@linux.ibm.com> (raw)
In-Reply-To: <20221128024458.46121-1-bgray@linux.ibm.com>
The ISA 3.1B hashst and hashchk instructions use a per-cpu SPR HASHKEYR
to hold a key used in the hash calculation. This key should be different
for each process to make it harder for a malicious process to recreate
valid hash values for a victim process.
Add support for storing a per-thread hash key, and setting/clearing
HASHKEYR appropriately.
Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
---
arch/powerpc/include/asm/book3s/64/kexec.h | 3 +++
arch/powerpc/include/asm/processor.h | 1 +
arch/powerpc/include/asm/reg.h | 1 +
arch/powerpc/kernel/process.c | 12 ++++++++++++
4 files changed, 17 insertions(+)
diff --git a/arch/powerpc/include/asm/book3s/64/kexec.h b/arch/powerpc/include/asm/book3s/64/kexec.h
index 563baf94a962..163de935df28 100644
--- a/arch/powerpc/include/asm/book3s/64/kexec.h
+++ b/arch/powerpc/include/asm/book3s/64/kexec.h
@@ -24,6 +24,9 @@ static inline void reset_sprs(void)
if (cpu_has_feature(CPU_FTR_ARCH_31))
mtspr(SPRN_DEXCR, 0);
+ if (cpu_has_feature(CPU_FTR_DEXCR_NPHIE))
+ mtspr(SPRN_HASHKEYR, 0);
+
/* Do we need isync()? We are going via a kexec reset */
isync();
}
diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
index c17ec1e44c86..2381217c95dc 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -264,6 +264,7 @@ struct thread_struct {
unsigned long mmcr3;
unsigned long sier2;
unsigned long sier3;
+ unsigned long hashkeyr;
#endif
};
diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index cdd1f174c399..854664cf844f 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -384,6 +384,7 @@
#define SPRN_HRMOR 0x139 /* Real mode offset register */
#define SPRN_HSRR0 0x13A /* Hypervisor Save/Restore 0 */
#define SPRN_HSRR1 0x13B /* Hypervisor Save/Restore 1 */
+#define SPRN_HASHKEYR 0x1D4 /* Non-privileged hashst/hashchk key register */
#define SPRN_ASDR 0x330 /* Access segment descriptor register */
#define SPRN_DEXCR 0x33C /* Dynamic execution control register */
#define DEXCR_PRO_MASK(aspect) __MASK(63 - (32 + (aspect))) /* Aspect number to problem state aspect mask */
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 17d26f652b80..4d7b0c7641d0 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1229,6 +1229,9 @@ static inline void restore_sprs(struct thread_struct *old_thread,
old_thread->tidr != new_thread->tidr)
mtspr(SPRN_TIDR, new_thread->tidr);
+ if (cpu_has_feature(CPU_FTR_DEXCR_NPHIE))
+ mtspr(SPRN_HASHKEYR, new_thread->hashkeyr);
+
if (cpu_has_feature(CPU_FTR_ARCH_31)) {
unsigned long new_dexcr = get_thread_dexcr(new_thread);
@@ -1818,6 +1821,10 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
childregs->ppr = DEFAULT_PPR;
p->thread.tidr = 0;
+#endif
+#ifdef CONFIG_PPC_BOOK3S_64
+ if (cpu_has_feature(CPU_FTR_DEXCR_NPHIE))
+ p->thread.hashkeyr = current->thread.hashkeyr;
#endif
/*
* Run with the current AMR value of the kernel
@@ -1947,6 +1954,11 @@ void start_thread(struct pt_regs *regs, unsigned long start, unsigned long sp)
current->thread.load_tm = 0;
#endif /* CONFIG_PPC_TRANSACTIONAL_MEM */
#ifdef CONFIG_PPC_BOOK3S_64
+ if (cpu_has_feature(CPU_FTR_DEXCR_NPHIE)) {
+ current->thread.hashkeyr = get_random_long();
+ mtspr(SPRN_HASHKEYR, current->thread.hashkeyr);
+ }
+
if (cpu_has_feature(CPU_FTR_ARCH_31))
mtspr(SPRN_DEXCR, get_thread_dexcr(¤t->thread));
#endif /* CONFIG_PPC_BOOK3S_64 */
--
2.38.1
next prev parent reply other threads:[~2022-11-28 2:47 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-28 2:44 [RFC PATCH 00/13] Add DEXCR support Benjamin Gray
2022-11-28 2:44 ` [RFC PATCH 01/13] powerpc/book3s: Add missing <linux/sched.h> include Benjamin Gray
2023-03-07 4:28 ` Nicholas Piggin
2022-11-28 2:44 ` [RFC PATCH 02/13] powerpc: Add initial Dynamic Execution Control Register (DEXCR) support Benjamin Gray
2023-03-07 4:45 ` Nicholas Piggin
2023-03-09 23:46 ` Benjamin Gray
2022-11-28 2:44 ` [RFC PATCH 03/13] powerpc/dexcr: Handle hashchk exception Benjamin Gray
2022-11-29 10:39 ` Nicholas Piggin
2022-11-29 22:04 ` Benjamin Gray
2022-11-28 2:44 ` Benjamin Gray [this message]
2023-03-07 5:05 ` [RFC PATCH 04/13] powerpc/dexcr: Support userspace ROP protection Nicholas Piggin
2023-03-07 5:37 ` Benjamin Gray
2023-03-21 4:51 ` Nicholas Piggin
2022-11-28 2:44 ` [RFC PATCH 05/13] prctl: Define PowerPC DEXCR interface Benjamin Gray
2023-03-07 5:07 ` Nicholas Piggin
2022-11-28 2:44 ` [RFC PATCH 06/13] powerpc/dexcr: Add prctl implementation Benjamin Gray
2023-03-07 5:12 ` Nicholas Piggin
2022-11-28 2:44 ` [RFC PATCH 07/13] powerpc/dexcr: Add sysctl entry for SBHE system override Benjamin Gray
2023-03-07 5:30 ` Nicholas Piggin
2023-03-07 5:58 ` Benjamin Gray
2022-11-28 2:44 ` [RFC PATCH 08/13] powerpc/dexcr: Add enforced userspace ROP protection config Benjamin Gray
2022-11-28 2:44 ` [RFC PATCH 09/13] selftests/powerpc: Add more utility macros Benjamin Gray
2022-11-28 2:44 ` [RFC PATCH 10/13] selftests/powerpc: Add hashst/hashchk test Benjamin Gray
2022-11-28 2:44 ` [RFC PATCH 11/13] selftests/powerpc: Add DEXCR prctl, sysctl interface test Benjamin Gray
2022-11-28 2:44 ` [RFC PATCH 12/13] selftests/powerpc: Add DEXCR status utility lsdexcr Benjamin Gray
2022-11-28 2:44 ` [RFC PATCH 13/13] Documentation: Document PowerPC kernel DEXCR interface Benjamin Gray
2023-03-07 5:40 ` Nicholas Piggin
2023-03-07 5:52 ` Benjamin Gray
2022-11-28 4:05 ` [RFC PATCH 00/13] Add DEXCR support Russell Currey
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20221128024458.46121-5-bgray@linux.ibm.com \
--to=bgray@linux.ibm.com \
--cc=ajd@linux.ibm.com \
--cc=cmr@bluescreens.de \
--cc=linux-hardening@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).