diff options
| author | Benjamin Gray <bgray@linux.ibm.com> | 2023-06-19 17:36:26 +1000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2023-06-19 17:36:26 +1000 |
| commit | be98fcf7c10dea74e9c3e2cd0018e47bdee67442 (patch) | |
| tree | 2536fca1dfd218dd60b68e8eb7b222e82e849f79 /arch/powerpc/kernel/process.c | |
| parent | 5bcba4e6c13f0c889da1f9e67ee10accd9ca4c19 (diff) | |
powerpc/dexcr: Support userspace ROP protection
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>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230616034846.311705-6-bgray@linux.ibm.com
Diffstat (limited to 'arch/powerpc/kernel/process.c')
| -rw-r--r-- | arch/powerpc/kernel/process.c | 17 |
1 files changed, 17 insertions, 0 deletions
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 } @@ -1868,6 +1875,10 @@ 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); |