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| author | Sven Schnelle <svens@linux.ibm.com> | 2021-04-29 11:14:51 +0200 |
|---|---|---|
| committer | Heiko Carstens <hca@linux.ibm.com> | 2021-04-30 17:20:39 +0200 |
| commit | bae1cd368c45d1127e054e90305d585dbc8b3b46 (patch) | |
| tree | 07224dd0189f8d3d63f1582a3ef7850250d884d0 | |
| parent | f5b474decad90719e2a4234f83d97aad19307584 (diff) | |
| download | linux-bae1cd368c45d1127e054e90305d585dbc8b3b46.tar.gz linux-bae1cd368c45d1127e054e90305d585dbc8b3b46.tar.bz2 linux-bae1cd368c45d1127e054e90305d585dbc8b3b46.zip | |
s390/entry: add support for syscall stack randomization
This adds support for adding a random offset to the stack while handling
syscalls. The patch uses get_tod_clock_fast() as this is considered good
enough and has much less performance penalty compared to using
get_random_int(). The patch also adds randomization in pgm_check_handler()
as the sigreturn/rt_sigreturn system calls might be called from there.
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Link: https://lore.kernel.org/r/20210429091451.1062594-1-svens@linux.ibm.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
| -rw-r--r-- | arch/s390/Kconfig | 1 | ||||
| -rw-r--r-- | arch/s390/include/asm/entry-common.h | 10 | ||||
| -rw-r--r-- | arch/s390/kernel/syscall.c | 1 | ||||
| -rw-r--r-- | arch/s390/kernel/traps.c | 2 |
4 files changed, 14 insertions, 0 deletions
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index c1ff874e6c2e..1900428ce557 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -137,6 +137,7 @@ config S390 select HAVE_ARCH_JUMP_LABEL_RELATIVE select HAVE_ARCH_KASAN select HAVE_ARCH_KASAN_VMALLOC + select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET select HAVE_ARCH_SECCOMP_FILTER select HAVE_ARCH_SOFT_DIRTY select HAVE_ARCH_TRACEHOOK diff --git a/arch/s390/include/asm/entry-common.h b/arch/s390/include/asm/entry-common.h index 9cceb26ed63f..baa8005090c3 100644 --- a/arch/s390/include/asm/entry-common.h +++ b/arch/s390/include/asm/entry-common.h @@ -4,9 +4,11 @@ #include <linux/sched.h> #include <linux/audit.h> +#include <linux/randomize_kstack.h> #include <linux/tracehook.h> #include <linux/processor.h> #include <linux/uaccess.h> +#include <asm/timex.h> #include <asm/fpu/api.h> #define ARCH_EXIT_TO_USER_MODE_WORK (_TIF_GUARDED_STORAGE | _TIF_PER_TRAP) @@ -48,6 +50,14 @@ static __always_inline void arch_exit_to_user_mode(void) #define arch_exit_to_user_mode arch_exit_to_user_mode +static inline void arch_exit_to_user_mode_prepare(struct pt_regs *regs, + unsigned long ti_work) +{ + choose_random_kstack_offset(get_tod_clock_fast() & 0xff); +} + +#define arch_exit_to_user_mode_prepare arch_exit_to_user_mode_prepare + static inline bool on_thread_stack(void) { return !(((unsigned long)(current->stack) ^ current_stack_pointer()) & ~(THREAD_SIZE - 1)); diff --git a/arch/s390/kernel/syscall.c b/arch/s390/kernel/syscall.c index bc8e650e377d..4e5cc7d2364e 100644 --- a/arch/s390/kernel/syscall.c +++ b/arch/s390/kernel/syscall.c @@ -142,6 +142,7 @@ void do_syscall(struct pt_regs *regs) void noinstr __do_syscall(struct pt_regs *regs, int per_trap) { + add_random_kstack_offset(); enter_from_user_mode(regs); memcpy(®s->gprs[8], S390_lowcore.save_area_sync, 8 * sizeof(unsigned long)); diff --git a/arch/s390/kernel/traps.c b/arch/s390/kernel/traps.c index 63021d484626..8dd23c703718 100644 --- a/arch/s390/kernel/traps.c +++ b/arch/s390/kernel/traps.c @@ -17,6 +17,7 @@ #include "asm/ptrace.h" #include <linux/kprobes.h> #include <linux/kdebug.h> +#include <linux/randomize_kstack.h> #include <linux/extable.h> #include <linux/ptrace.h> #include <linux/sched.h> @@ -301,6 +302,7 @@ void noinstr __do_pgm_check(struct pt_regs *regs) unsigned int trapnr, syscall_redirect = 0; irqentry_state_t state; + add_random_kstack_offset(); regs->int_code = *(u32 *)&S390_lowcore.pgm_ilc; regs->int_parm_long = S390_lowcore.trans_exc_code; |