[PATCH] s390: put sys_call_table into .rodata section and write protect it
Put s390's syscall tables into .rodata section and write protect this
section to prevent misuse of it. Suggested by Arjan van de Ven
<arjan@infradead.org>.
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index 1a434a7..d8948c3 100644
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -228,8 +228,9 @@
sysc_nr_ok:
mvc SP_ARGS(4,%r15),SP_R7(%r15)
sysc_do_restart:
+ l %r8,BASED(.Lsysc_table)
tm __TI_flags+3(%r9),(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT)
- l %r8,sys_call_table-system_call(%r7,%r13) # get system call addr.
+ l %r8,0(%r7,%r8) # get system call addr.
bnz BASED(sysc_tracesys)
basr %r14,%r8 # call sys_xxxx
st %r2,SP_R2(%r15) # store return value (change R2 on stack)
@@ -330,9 +331,10 @@
basr %r14,%r1
clc SP_R2(4,%r15),BASED(.Lnr_syscalls)
bnl BASED(sysc_tracenogo)
+ l %r8,BASED(.Lsysc_table)
l %r7,SP_R2(%r15) # strace might have changed the
sll %r7,2 # system call
- l %r8,sys_call_table-system_call(%r7,%r13)
+ l %r8,0(%r7,%r8)
sysc_tracego:
lm %r3,%r6,SP_R3(%r15)
l %r2,SP_ORIG_R2(%r15)
@@ -1009,6 +1011,7 @@
.Ltrace: .long syscall_trace
.Lvfork: .long sys_vfork
.Lschedtail: .long schedule_tail
+.Lsysc_table: .long sys_call_table
.Lcritical_start:
.long __critical_start + 0x80000000
@@ -1017,8 +1020,8 @@
.Lcleanup_critical:
.long cleanup_critical
+ .section .rodata, "a"
#define SYSCALL(esa,esame,emu) .long esa
sys_call_table:
#include "syscalls.S"
#undef SYSCALL
-
diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S
index edad607..1ca499f 100644
--- a/arch/s390/kernel/entry64.S
+++ b/arch/s390/kernel/entry64.S
@@ -991,6 +991,7 @@
.Lcritical_end:
.quad __critical_end
+ .section .rodata, "a"
#define SYSCALL(esa,esame,emu) .long esame
sys_call_table:
#include "syscalls.S"
diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
index 81dce185..eb6ebfe 100644
--- a/arch/s390/mm/init.c
+++ b/arch/s390/mm/init.c
@@ -23,6 +23,7 @@
#include <linux/init.h>
#include <linux/pagemap.h>
#include <linux/bootmem.h>
+#include <linux/pfn.h>
#include <asm/processor.h>
#include <asm/system.h>
@@ -33,6 +34,7 @@
#include <asm/lowcore.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>
+#include <asm/sections.h>
DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
@@ -89,17 +91,6 @@
printk("%d pages swap cached\n",cached);
}
-/* References to section boundaries */
-
-extern unsigned long _text;
-extern unsigned long _etext;
-extern unsigned long _edata;
-extern unsigned long __bss_start;
-extern unsigned long _end;
-
-extern unsigned long __init_begin;
-extern unsigned long __init_end;
-
extern unsigned long __initdata zholes_size[];
/*
* paging_init() sets up the page tables
@@ -116,6 +107,10 @@
unsigned long pfn = 0;
unsigned long pgdir_k = (__pa(swapper_pg_dir) & PAGE_MASK) | _KERNSEG_TABLE;
static const int ssm_mask = 0x04000000L;
+ unsigned long ro_start_pfn, ro_end_pfn;
+
+ ro_start_pfn = PFN_DOWN((unsigned long)&__start_rodata);
+ ro_end_pfn = PFN_UP((unsigned long)&__end_rodata);
/* unmap whole virtual address space */
@@ -143,7 +138,10 @@
pg_dir++;
for (tmp = 0 ; tmp < PTRS_PER_PTE ; tmp++,pg_table++) {
- pte = pfn_pte(pfn, PAGE_KERNEL);
+ if (pfn >= ro_start_pfn && pfn < ro_end_pfn)
+ pte = pfn_pte(pfn, __pgprot(_PAGE_RO));
+ else
+ pte = pfn_pte(pfn, PAGE_KERNEL);
if (pfn >= max_low_pfn)
pte_clear(&init_mm, 0, &pte);
set_pte(pg_table, pte);
@@ -175,6 +173,7 @@
}
#else /* CONFIG_64BIT */
+
void __init paging_init(void)
{
pgd_t * pg_dir;
@@ -186,13 +185,15 @@
unsigned long pgdir_k = (__pa(swapper_pg_dir) & PAGE_MASK) |
_KERN_REGION_TABLE;
static const int ssm_mask = 0x04000000L;
-
unsigned long zones_size[MAX_NR_ZONES];
unsigned long dma_pfn, high_pfn;
+ unsigned long ro_start_pfn, ro_end_pfn;
memset(zones_size, 0, sizeof(zones_size));
dma_pfn = MAX_DMA_ADDRESS >> PAGE_SHIFT;
high_pfn = max_low_pfn;
+ ro_start_pfn = PFN_DOWN((unsigned long)&__start_rodata);
+ ro_end_pfn = PFN_UP((unsigned long)&__end_rodata);
if (dma_pfn > high_pfn)
zones_size[ZONE_DMA] = high_pfn;
@@ -231,7 +232,10 @@
pmd_populate_kernel(&init_mm, pm_dir, pt_dir);
for (k = 0 ; k < PTRS_PER_PTE ; k++,pt_dir++) {
- pte = pfn_pte(pfn, PAGE_KERNEL);
+ if (pfn >= ro_start_pfn && pfn < ro_end_pfn)
+ pte = pfn_pte(pfn, __pgprot(_PAGE_RO));
+ else
+ pte = pfn_pte(pfn, PAGE_KERNEL);
if (pfn >= max_low_pfn) {
pte_clear(&init_mm, 0, &pte);
continue;
@@ -282,6 +286,9 @@
reservedpages << (PAGE_SHIFT-10),
datasize >>10,
initsize >> 10);
+ printk("Write protected kernel read-only data: %#lx - %#lx\n",
+ (unsigned long)&__start_rodata,
+ PFN_ALIGN((unsigned long)&__end_rodata) - 1);
}
void free_initmem(void)