From: Benjamin Gray <bgray@linux.ibm.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: Benjamin Gray <bgray@linux.ibm.com>,
ajd@linux.ibm.com, npiggin@gmail.com, ruscur@russell.cc
Subject: [PATCH v3 05/12] powerpc/dexcr: Support userspace ROP protection
Date: Fri, 19 May 2023 15:02:29 +1000 [thread overview]
Message-ID: <20230519050236.144847-6-bgray@linux.ibm.com> (raw)
In-Reply-To: <20230519050236.144847-1-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>
Reviewed-by: Russell Currey <ruscur@russell.cc>
---
v3: * Add ruscur reviewed-by
v1: * Guard HASHKEYR update behind change check
* HASHKEYR reset moved earlier to patch 2
---
arch/powerpc/include/asm/processor.h | 1 +
arch/powerpc/kernel/process.c | 17 +++++++++++++++++
2 files changed, 18 insertions(+)
diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
index e96c9b8c2a60..8a6754ffdc7e 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/kernel/process.c b/arch/powerpc/kernel/process.c
index 1fefafb2b29b..b68898ac07e1 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1182,6 +1182,9 @@ static inline void save_sprs(struct thread_struct *t)
*/
t->tar = mfspr(SPRN_TAR);
}
+
+ if (cpu_has_feature(CPU_FTR_DEXCR_NPHIE))
+ t->hashkeyr = mfspr(SPRN_HASHKEYR);
#endif
}
@@ -1260,6 +1263,10 @@ static inline void restore_sprs(struct thread_struct *old_thread,
if (cpu_has_feature(CPU_FTR_P9_TIDR) &&
old_thread->tidr != new_thread->tidr)
mtspr(SPRN_TIDR, new_thread->tidr);
+
+ if (cpu_has_feature(CPU_FTR_DEXCR_NPHIE) &&
+ old_thread->hashkeyr != new_thread->hashkeyr)
+ mtspr(SPRN_HASHKEYR, new_thread->hashkeyr);
#endif
}
@@ -1867,6 +1874,10 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
}
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
return 0;
}
@@ -1984,6 +1995,12 @@ void start_thread(struct pt_regs *regs, unsigned long start, unsigned long sp)
current->thread.tm_tfiar = 0;
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);
+ }
+#endif /* CONFIG_PPC_BOOK3S_64 */
}
EXPORT_SYMBOL(start_thread);
--
2.40.1
next prev parent reply other threads:[~2023-05-19 5:07 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-19 5:02 [PATCH v3 00/12] Add static DEXCR support Benjamin Gray
2023-05-19 5:02 ` [PATCH v3 01/12] powerpc/book3s: Add missing <linux/sched.h> include Benjamin Gray
2023-05-23 6:45 ` Andrew Donnellan
2023-05-19 5:02 ` [PATCH v3 02/12] powerpc/ptrace: Add missing <linux/regset.h> include Benjamin Gray
2023-05-23 6:51 ` Andrew Donnellan
2023-05-19 5:02 ` [PATCH v3 03/12] powerpc/dexcr: Add initial Dynamic Execution Control Register (DEXCR) support Benjamin Gray
2023-05-19 5:02 ` [PATCH v3 04/12] powerpc/dexcr: Handle hashchk exception Benjamin Gray
2023-05-19 5:02 ` Benjamin Gray [this message]
2023-05-19 5:02 ` [PATCH v3 06/12] powerpc/dexcr: Support custom default DEXCR value Benjamin Gray
2023-05-19 5:02 ` [PATCH v3 07/12] powerpc/ptrace: Expose DEXCR and HDEXCR registers to ptrace Benjamin Gray
2023-05-19 5:02 ` [PATCH v3 08/12] powerpc/ptrace: Expose HASHKEYR register " Benjamin Gray
2023-05-19 5:02 ` [PATCH v3 09/12] Documentation: Document PowerPC kernel DEXCR interface Benjamin Gray
2023-05-19 5:02 ` [PATCH v3 10/12] selftests/powerpc: Add more utility macros Benjamin Gray
2023-05-19 5:02 ` [PATCH v3 11/12] selftests/powerpc/dexcr: Add hashst/hashchk test Benjamin Gray
2023-05-19 5:02 ` [PATCH v3 12/12] selftests/powerpc/dexcr: Add DEXCR status utility lsdexcr Benjamin Gray
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