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powerpc: Add skeleton for Kernel Userspace Execution Prevention

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This patch adds a skeleton for Kernel Userspace Execution Prevention.

Then subarches implementing it have to define CONFIG_PPC_HAVE_KUEP
and provide setup_kuep() function.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
[mpe: Don't split strings, use pr_crit_ratelimited()]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Christophe Leroy 2019-04-18 16:51:19 +10:00 committed by Michael Ellerman
parent 69795cabe4
commit 0fb1c25ab5
5 changed files with 34 additions and 6 deletions
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2
Documentation/admin-guide/kernel-parameters.txt
View File

@ -2843,7 +2843,7 @@
Disable SMAP (Supervisor Mode Access Prevention)
even if it is supported by processor.
nosmep [X86]
nosmep [X86,PPC]
Disable SMEP (Supervisor Mode Execution Prevention)
even if it is supported by processor.

6
arch/powerpc/include/asm/kup.h
View File

@ -6,6 +6,12 @@
void setup_kup(void);
#ifdef CONFIG_PPC_KUEP
void setup_kuep(bool disabled);
#else
static inline void setup_kuep(bool disabled) { }
#endif /* CONFIG_PPC_KUEP */
#endif /* !__ASSEMBLY__ */
#endif /* _ASM_POWERPC_KUP_H_ */

9
arch/powerpc/mm/fault.c
View File

@ -229,11 +229,10 @@ static bool bad_kernel_fault(bool is_exec, unsigned long error_code,
/* NX faults set DSISR_PROTFAULT on the 8xx, DSISR_NOEXEC_OR_G on others */
if (is_exec && (error_code & (DSISR_NOEXEC_OR_G | DSISR_KEYFAULT |
DSISR_PROTFAULT))) {
printk_ratelimited(KERN_CRIT "kernel tried to execute"
" exec-protected page (%lx) -"
"exploit attempt? (uid: %d)\n",
address, from_kuid(&init_user_ns,
current_uid()));
pr_crit_ratelimited("kernel tried to execute %s page (%lx) - exploit attempt? (uid: %d)\n",
address >= TASK_SIZE ? "exec-protected" : "user",
address,
from_kuid(&init_user_ns, current_uid()));
}
return is_exec || (address >= TASK_SIZE);
}

11
arch/powerpc/mm/init-common.c
View File

@ -26,8 +26,19 @@
#include <asm/pgtable.h>
#include <asm/kup.h>
static bool disable_kuep = !IS_ENABLED(CONFIG_PPC_KUEP);
static int __init parse_nosmep(char *p)
{
disable_kuep = true;
pr_warn("Disabling Kernel Userspace Execution Prevention\n");
return 0;
}
early_param("nosmep", parse_nosmep);
void __init setup_kup(void)
{
setup_kuep(disable_kuep);
}
#define CTOR(shift) static void ctor_##shift(void *addr) \

12
arch/powerpc/platforms/Kconfig.cputype
View File

@ -345,6 +345,18 @@ config PPC_RADIX_MMU_DEFAULT
If you're unsure, say Y.
config PPC_HAVE_KUEP
bool
config PPC_KUEP
bool "Kernel Userspace Execution Prevention"
depends on PPC_HAVE_KUEP
default y
help
Enable support for Kernel Userspace Execution Prevention (KUEP)
If you're unsure, say Y.
config ARCH_ENABLE_HUGEPAGE_MIGRATION
def_bool y
depends on PPC_BOOK3S_64 && HUGETLB_PAGE && MIGRATION