From: Alexandre Ghiti <alex@ghiti.fr>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Luis Chamberlain <mcgrof@kernel.org>,
Christoph Hellwig <hch@lst.de>,
Russell King <linux@armlinux.org.uk>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
Ralf Baechle <ralf@linux-mips.org>,
Paul Burton <paul.burton@mips.com>,
James Hogan <jhogan@kernel.org>,
Palmer Dabbelt <palmer@sifive.com>,
Albert Ou <aou@eecs.berkeley.edu>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Kees Cook <keescook@chromium.org>,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org,
linux-riscv@lists.infradead.org, linux-fsdevel@vger.kernel.org,
linux-mm@kvack.org, Alexandre Ghiti <alex@ghiti.fr>,
Christoph Hellwig <hch@infradead.org>
Subject: [PATCH v5 04/14] arm64, mm: Move generic mmap layout functions to mm
Date: Tue, 30 Jul 2019 01:51:03 -0400 [thread overview]
Message-ID: <20190730055113.23635-5-alex@ghiti.fr> (raw)
In-Reply-To: <20190730055113.23635-1-alex@ghiti.fr>
arm64 handles top-down mmap layout in a way that can be easily reused
by other architectures, so make it available in mm.
It then introduces a new config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
that can be set by other architectures to benefit from those functions.
Note that this new config depends on MMU being enabled, if selected
without MMU support, a warning will be thrown.
Suggested-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
---
arch/Kconfig | 10 ++++
arch/arm64/Kconfig | 1 +
arch/arm64/include/asm/processor.h | 2 -
arch/arm64/mm/mmap.c | 76 -----------------------------
kernel/sysctl.c | 6 ++-
mm/util.c | 78 +++++++++++++++++++++++++++++-
6 files changed, 92 insertions(+), 81 deletions(-)
diff --git a/arch/Kconfig b/arch/Kconfig
index a7b57dd42c26..a0bb6fa4d381 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -696,6 +696,16 @@ config HAVE_ARCH_COMPAT_MMAP_BASES
and vice-versa 32-bit applications to call 64-bit mmap().
Required for applications doing different bitness syscalls.
+# This allows to use a set of generic functions to determine mmap base
+# address by giving priority to top-down scheme only if the process
+# is not in legacy mode (compat task, unlimited stack size or
+# sysctl_legacy_va_layout).
+# Architecture that selects this option can provide its own version of:
+# - STACK_RND_MASK
+config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
+ bool
+ depends on MMU
+
config HAVE_COPY_THREAD_TLS
bool
help
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 3adcec05b1f6..14a194e63458 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -72,6 +72,7 @@ config ARM64
select ARCH_SUPPORTS_INT128 if GCC_VERSION >= 50000 || CC_IS_CLANG
select ARCH_SUPPORTS_NUMA_BALANCING
select ARCH_WANT_COMPAT_IPC_PARSE_VERSION if COMPAT
+ select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
select ARCH_WANT_FRAME_POINTERS
select ARCH_WANT_HUGE_PMD_SHARE if ARM64_4K_PAGES || (ARM64_16K_PAGES && !ARM64_VA_BITS_36)
select ARCH_HAS_UBSAN_SANITIZE_ALL
diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
index 844e2964b0f5..65e2de00913f 100644
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -281,8 +281,6 @@ static inline void spin_lock_prefetch(const void *ptr)
"nop") : : "p" (ptr));
}
-#define HAVE_ARCH_PICK_MMAP_LAYOUT
-
#endif
extern unsigned long __ro_after_init signal_minsigstksz; /* sigframe size */
diff --git a/arch/arm64/mm/mmap.c b/arch/arm64/mm/mmap.c
index e4acaead67de..3028bacbc4e9 100644
--- a/arch/arm64/mm/mmap.c
+++ b/arch/arm64/mm/mmap.c
@@ -20,82 +20,6 @@
#include <asm/cputype.h>
-/*
- * Leave enough space between the mmap area and the stack to honour ulimit in
- * the face of randomisation.
- */
-#define MIN_GAP (SZ_128M)
-#define MAX_GAP (STACK_TOP/6*5)
-
-static int mmap_is_legacy(struct rlimit *rlim_stack)
-{
- if (current->personality & ADDR_COMPAT_LAYOUT)
- return 1;
-
- if (rlim_stack->rlim_cur == RLIM_INFINITY)
- return 1;
-
- return sysctl_legacy_va_layout;
-}
-
-unsigned long arch_mmap_rnd(void)
-{
- unsigned long rnd;
-
-#ifdef CONFIG_COMPAT
- if (is_compat_task())
- rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1);
- else
-#endif
- rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);
- return rnd << PAGE_SHIFT;
-}
-
-static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack)
-{
- unsigned long gap = rlim_stack->rlim_cur;
- unsigned long pad = stack_guard_gap;
-
- /* Account for stack randomization if necessary */
- if (current->flags & PF_RANDOMIZE)
- pad += (STACK_RND_MASK << PAGE_SHIFT);
-
- /* Values close to RLIM_INFINITY can overflow. */
- if (gap + pad > gap)
- gap += pad;
-
- if (gap < MIN_GAP)
- gap = MIN_GAP;
- else if (gap > MAX_GAP)
- gap = MAX_GAP;
-
- return PAGE_ALIGN(STACK_TOP - gap - rnd);
-}
-
-/*
- * This function, called very early during the creation of a new process VM
- * image, sets up which VM layout function to use:
- */
-void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
-{
- unsigned long random_factor = 0UL;
-
- if (current->flags & PF_RANDOMIZE)
- random_factor = arch_mmap_rnd();
-
- /*
- * Fall back to the standard layout if the personality bit is set, or
- * if the expected stack growth is unlimited:
- */
- if (mmap_is_legacy(rlim_stack)) {
- mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
- mm->get_unmapped_area = arch_get_unmapped_area;
- } else {
- mm->mmap_base = mmap_base(random_factor, rlim_stack);
- mm->get_unmapped_area = arch_get_unmapped_area_topdown;
- }
-}
-
/*
* You really shouldn't be using read() or write() on /dev/mem. This might go
* away in the future.
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 078950d9605b..00fcea236eba 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -264,7 +264,8 @@ extern struct ctl_table epoll_table[];
extern struct ctl_table firmware_config_table[];
#endif
-#ifdef HAVE_ARCH_PICK_MMAP_LAYOUT
+#if defined(HAVE_ARCH_PICK_MMAP_LAYOUT) || \
+ defined(CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT)
int sysctl_legacy_va_layout;
#endif
@@ -1573,7 +1574,8 @@ static struct ctl_table vm_table[] = {
.proc_handler = proc_dointvec,
.extra1 = SYSCTL_ZERO,
},
-#ifdef HAVE_ARCH_PICK_MMAP_LAYOUT
+#if defined(HAVE_ARCH_PICK_MMAP_LAYOUT) || \
+ defined(CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT)
{
.procname = "legacy_va_layout",
.data = &sysctl_legacy_va_layout,
diff --git a/mm/util.c b/mm/util.c
index 15a4fb0f5473..0781e5575cb3 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -17,7 +17,12 @@
#include <linux/vmalloc.h>
#include <linux/userfaultfd_k.h>
#include <linux/elf.h>
+#include <linux/elf-randomize.h>
+#include <linux/personality.h>
#include <linux/random.h>
+#include <linux/processor.h>
+#include <linux/sizes.h>
+#include <linux/compat.h>
#include <linux/uaccess.h>
@@ -315,7 +320,78 @@ unsigned long randomize_stack_top(unsigned long stack_top)
#endif
}
-#if defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT)
+#ifdef CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
+#ifdef CONFIG_ARCH_HAS_ELF_RANDOMIZE
+unsigned long arch_mmap_rnd(void)
+{
+ unsigned long rnd;
+
+#ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
+ if (is_compat_task())
+ rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1);
+ else
+#endif /* CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS */
+ rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);
+
+ return rnd << PAGE_SHIFT;
+}
+#endif /* CONFIG_ARCH_HAS_ELF_RANDOMIZE */
+
+static int mmap_is_legacy(struct rlimit *rlim_stack)
+{
+ if (current->personality & ADDR_COMPAT_LAYOUT)
+ return 1;
+
+ if (rlim_stack->rlim_cur == RLIM_INFINITY)
+ return 1;
+
+ return sysctl_legacy_va_layout;
+}
+
+/*
+ * Leave enough space between the mmap area and the stack to honour ulimit in
+ * the face of randomisation.
+ */
+#define MIN_GAP (SZ_128M)
+#define MAX_GAP (STACK_TOP / 6 * 5)
+
+static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack)
+{
+ unsigned long gap = rlim_stack->rlim_cur;
+ unsigned long pad = stack_guard_gap;
+
+ /* Account for stack randomization if necessary */
+ if (current->flags & PF_RANDOMIZE)
+ pad += (STACK_RND_MASK << PAGE_SHIFT);
+
+ /* Values close to RLIM_INFINITY can overflow. */
+ if (gap + pad > gap)
+ gap += pad;
+
+ if (gap < MIN_GAP)
+ gap = MIN_GAP;
+ else if (gap > MAX_GAP)
+ gap = MAX_GAP;
+
+ return PAGE_ALIGN(STACK_TOP - gap - rnd);
+}
+
+void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
+{
+ unsigned long random_factor = 0UL;
+
+ if (current->flags & PF_RANDOMIZE)
+ random_factor = arch_mmap_rnd();
+
+ if (mmap_is_legacy(rlim_stack)) {
+ mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
+ mm->get_unmapped_area = arch_get_unmapped_area;
+ } else {
+ mm->mmap_base = mmap_base(random_factor, rlim_stack);
+ mm->get_unmapped_area = arch_get_unmapped_area_topdown;
+ }
+}
+#elif defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT)
void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
{
mm->mmap_base = TASK_UNMAPPED_BASE;
--
2.20.1
next prev parent reply other threads:[~2019-07-30 5:55 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-30 5:50 [PATCH v5 00/14] Provide generic top-down mmap layout functions Alexandre Ghiti
2019-07-30 5:51 ` [PATCH v5 01/14] mm, fs: Move randomize_stack_top from fs to mm Alexandre Ghiti
2019-07-30 5:51 ` [PATCH v5 02/14] arm64: Make use of is_compat_task instead of hardcoding this test Alexandre Ghiti
2019-07-30 5:51 ` [PATCH v5 03/14] arm64: Consider stack randomization for mmap base only when necessary Alexandre Ghiti
2019-07-30 5:51 ` Alexandre Ghiti [this message]
2019-07-30 5:51 ` [PATCH v5 05/14] arm64, mm: Make randomization selected by generic topdown mmap layout Alexandre Ghiti
2019-07-30 5:51 ` [PATCH v5 06/14] arm: Properly account for stack randomization and stack guard gap Alexandre Ghiti
2019-07-30 5:51 ` [PATCH v5 07/14] arm: Use STACK_TOP when computing mmap base address Alexandre Ghiti
2019-07-30 5:51 ` [PATCH v5 08/14] arm: Use generic mmap top-down layout and brk randomization Alexandre Ghiti
2019-07-30 5:51 ` [PATCH v5 09/14] mips: Properly account for stack randomization and stack guard gap Alexandre Ghiti
2019-07-30 5:51 ` [PATCH v5 10/14] mips: Use STACK_TOP when computing mmap base address Alexandre Ghiti
2019-07-30 5:51 ` [PATCH v5 11/14] mips: Adjust brk randomization offset to fit generic version Alexandre Ghiti
2019-07-30 5:51 ` [PATCH v5 12/14] mips: Replace arch specific way to determine 32bit task with " Alexandre Ghiti
2019-07-30 5:51 ` [PATCH v5 13/14] mips: Use generic mmap top-down layout and brk randomization Alexandre Ghiti
2019-07-30 5:51 ` [PATCH v5 14/14] riscv: Make mmap allocation top-down by default Alexandre Ghiti
2019-07-31 6:05 ` Alex Ghiti
2019-07-31 17:33 ` Guenter Roeck
2019-07-31 22:40 ` Paul Walmsley
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