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Wed, 22 Mar 2023 05:46:35 +0000 (GMT) Received: from bgray-lenovo-p15.ozlabs.ibm.com (haven.au.ibm.com [9.192.254.114]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.au.ibm.com (Postfix) with ESMTPSA id 86E36605A7; Wed, 22 Mar 2023 16:46:32 +1100 (AEDT) From: Benjamin Gray To: linuxppc-dev@lists.ozlabs.org Subject: [PATCH 4/9] powerpc/dexcr: Support userspace ROP protection Date: Wed, 22 Mar 2023 16:46:07 +1100 Message-Id: <20230322054612.1340573-5-bgray@linux.ibm.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230322054612.1340573-1-bgray@linux.ibm.com> References: <20230322054612.1340573-1-bgray@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: wTifvRnYW1ZIxamS_JHhacfkCsELRQpy X-Proofpoint-GUID: wTifvRnYW1ZIxamS_JHhacfkCsELRQpy X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.254,Aquarius:18.0.942,Hydra:6.0.573,FMLib:17.11.170.22 definitions=2023-03-21_11,2023-03-21_01,2023-02-09_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 impostorscore=0 lowpriorityscore=0 bulkscore=0 phishscore=0 clxscore=1015 spamscore=0 malwarescore=0 mlxlogscore=907 mlxscore=0 priorityscore=1501 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2303150002 definitions=main-2303220039 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Benjamin Gray Errors-To: linuxppc-dev-bounces+incoming=patchwork.ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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 --- 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 bad64d6a5d36..666d4e9804a8 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 4b29ac5ddac6..62762795e24e 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 } @@ -1844,6 +1851,10 @@ 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 @@ -1972,6 +1983,12 @@ 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);