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(unknown [120.245.3.37]) by pv50p00im-ztdg10011301.me.com (Postfix) with ESMTPSA id 782BE760284; Tue, 21 Sep 2021 11:04:36 +0000 (UTC) From: sxwjean@me.com To: x86@kernel.org, linux-mm@kvack.org Cc: sxwjean@me.com, Xiongwei Song Subject: [PATCH 2/2] x86/mm: Randomize va with generic arch_pick_mmap_layout() Date: Tue, 21 Sep 2021 19:02:52 +0800 Message-Id: <20210921110252.2593542-3-sxwjean@me.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210921110252.2593542-1-sxwjean@me.com> References: <20210921110252.2593542-1-sxwjean@me.com> MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.790 definitions=2021-09-21_01:2021-09-20,2021-09-21 signatures=0 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 mlxscore=0 mlxlogscore=585 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-2009150000 definitions=main-2109210070 Authentication-Results: imf03.hostedemail.com; dkim=pass header.d=me.com header.s=1a1hai header.b=cxJG5WVZ; spf=pass (imf03.hostedemail.com: domain of sxwjean@me.com designates 17.58.6.40 as permitted sender) smtp.mailfrom=sxwjean@me.com; dmarc=pass (policy=quarantine) header.from=me.com X-Stat-Signature: 6nnyaezq15oafowpm86zxczp5xaidtrz X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: C730F30000A6 X-HE-Tag: 1632222281-204014 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Xiongwei Song The code logic of arch_pick_mmap_layout() of x86 is basiclly same as arch_pick_mmap_layout() in mm/util.c. Let's delete the function and the related assistant functions in x86. There are some differences between x86 and geneirc code: - mmap_is_legacy(), there is no check for stack limit of 32 bits process in x86, while generic code does, which is suitable for x86 too. - arch_randomize_brk(), it only randomized the brk with SZ_32M range for 32 bits and 64 bits processes, while the generic code randomizes br= k with SZ_1G range for 64 bits process, which is suitable for x86 too. - Implement is_compat_task(), which means 32 bits process in 64 bits kernel, to adapt generic implementation. - The special implementation of x86 is the code with CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES enabled. I assume other archs will enable CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES in the future, so move the implementation to the generic part. Hence select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT in x86 to use generic arch_pick_mmap_layout(). Meanwhile, the ARCH_HAS_ELF_RANDOMIZE can be enabled automatically, remove select for it. Signed-off-by: Xiongwei Song --- arch/x86/Kconfig | 2 +- arch/x86/include/asm/compat.h | 7 +- arch/x86/include/asm/processor.h | 4 +- arch/x86/kernel/process.c | 5 -- arch/x86/mm/mmap.c | 112 ------------------------------- include/linux/compat.h | 4 ++ mm/util.c | 18 ++++- 7 files changed, 29 insertions(+), 123 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index dad7f85dcdea..c081e6ff7f11 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -72,7 +72,6 @@ config X86 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE select ARCH_HAS_DEVMEM_IS_ALLOWED select ARCH_HAS_EARLY_DEBUG if KGDB - select ARCH_HAS_ELF_RANDOMIZE select ARCH_HAS_FAST_MULTIPLIER select ARCH_HAS_FILTER_PGPROT select ARCH_HAS_FORTIFY_SOURCE @@ -114,6 +113,7 @@ config X86 select ARCH_USE_SYM_ANNOTATIONS select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH select ARCH_WANT_DEFAULT_BPF_JIT if X86_64 + select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT select ARCH_WANTS_DYNAMIC_TASK_STRUCT select ARCH_WANTS_NO_INSTR select ARCH_WANT_HUGE_PMD_SHARE diff --git a/arch/x86/include/asm/compat.h b/arch/x86/include/asm/compat.= h index 7516e4199b3c..c697e377644d 100644 --- a/arch/x86/include/asm/compat.h +++ b/arch/x86/include/asm/compat.h @@ -151,6 +151,11 @@ struct compat_shmid64_ds { compat_ulong_t __unused5; }; =20 +static inline int is_compat_task(void) +{ + return IS_ENABLED(CONFIG_COMPAT) && test_thread_flag(TIF_32BIT); +} + #ifdef CONFIG_X86_X32_ABI #define COMPAT_USE_64BIT_TIME \ (!!(task_pt_regs(current)->orig_ax & __X32_SYSCALL_BIT)) @@ -165,12 +170,12 @@ static inline bool in_x32_syscall(void) return false; } =20 +#ifdef CONFIG_COMPAT static inline bool in_32bit_syscall(void) { return in_ia32_syscall() || in_x32_syscall(); } =20 -#ifdef CONFIG_COMPAT static inline bool in_compat_syscall(void) { return in_32bit_syscall(); diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/proc= essor.h index 9ad2acaaae9b..c28a36ee6eb0 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -708,7 +708,6 @@ extern int bootloader_version; =20 extern char ignore_fpu_irq; =20 -#define HAVE_ARCH_PICK_MMAP_LAYOUT 1 #define ARCH_HAS_PREFETCHW #define ARCH_HAS_SPINLOCK_PREFETCH =20 @@ -785,6 +784,9 @@ extern void start_thread(struct pt_regs *regs, unsign= ed long new_ip, */ #define __TASK_UNMAPPED_BASE(task_size) (PAGE_ALIGN(task_size / 3)) #define TASK_UNMAPPED_BASE __TASK_UNMAPPED_BASE(TASK_SIZE_LOW) +#ifdef CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES +#define TASK_UNMAPPED_COMPAT_BASE __TASK_UNMAPPED_BASE(task_size_32bit()= ) +#endif =20 #define KSTK_EIP(task) (task_pt_regs(task)->ip) =20 diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 1d9463e3096b..1e747d34c18d 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -931,11 +931,6 @@ unsigned long arch_align_stack(unsigned long sp) return sp & ~0xf; } =20 -unsigned long arch_randomize_brk(struct mm_struct *mm) -{ - return randomize_page(mm->brk, 0x02000000); -} - /* * Called from fs/proc with a reference on @p to find the function * which called into schedule(). This needs to be done carefully diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c index c90c20904a60..daf65cc5e5b1 100644 --- a/arch/x86/mm/mmap.c +++ b/arch/x86/mm/mmap.c @@ -38,118 +38,6 @@ unsigned long task_size_64bit(int full_addr_space) return full_addr_space ? TASK_SIZE_MAX : DEFAULT_MAP_WINDOW; } =20 -static unsigned long stack_maxrandom_size(unsigned long task_size) -{ - unsigned long max =3D 0; - if (current->flags & PF_RANDOMIZE) { - max =3D (-1UL) & __STACK_RND_MASK(task_size =3D=3D task_size_32bit()); - max <<=3D PAGE_SHIFT; - } - - return max; -} - -#ifdef CONFIG_COMPAT -# define mmap32_rnd_bits mmap_rnd_compat_bits -# define mmap64_rnd_bits mmap_rnd_bits -#else -# define mmap32_rnd_bits mmap_rnd_bits -# define mmap64_rnd_bits mmap_rnd_bits -#endif - -#define SIZE_128M (128 * 1024 * 1024UL) - -static int mmap_is_legacy(void) -{ - if (current->personality & ADDR_COMPAT_LAYOUT) - return 1; - - return sysctl_legacy_va_layout; -} - -static unsigned long arch_rnd(unsigned int rndbits) -{ - if (!(current->flags & PF_RANDOMIZE)) - return 0; - return (get_random_long() & ((1UL << rndbits) - 1)) << PAGE_SHIFT; -} - -unsigned long arch_mmap_rnd(void) -{ - return arch_rnd(mmap_is_ia32() ? mmap32_rnd_bits : mmap64_rnd_bits); -} - -static unsigned long mmap_base(unsigned long rnd, unsigned long task_siz= e, - struct rlimit *rlim_stack) -{ - unsigned long gap =3D rlim_stack->rlim_cur; - unsigned long pad =3D stack_maxrandom_size(task_size) + stack_guard_gap= ; - unsigned long gap_min, gap_max; - - /* Values close to RLIM_INFINITY can overflow. */ - if (gap + pad > gap) - gap +=3D pad; - - /* - * Top of mmap area (just below the process stack). - * Leave an at least ~128 MB hole with possible stack randomization. - */ - gap_min =3D SIZE_128M; - gap_max =3D (task_size / 6) * 5; - - if (gap < gap_min) - gap =3D gap_min; - else if (gap > gap_max) - gap =3D gap_max; - - return PAGE_ALIGN(task_size - gap - rnd); -} - -static unsigned long mmap_legacy_base(unsigned long rnd, - unsigned long task_size) -{ - return __TASK_UNMAPPED_BASE(task_size) + rnd; -} - -/* - * This function, called very early during the creation of a new - * process VM image, sets up which VM layout function to use: - */ -static void arch_pick_mmap_base(unsigned long *base, unsigned long *lega= cy_base, - unsigned long random_factor, unsigned long task_size, - struct rlimit *rlim_stack) -{ - *legacy_base =3D mmap_legacy_base(random_factor, task_size); - if (mmap_is_legacy()) - *base =3D *legacy_base; - else - *base =3D mmap_base(random_factor, task_size, rlim_stack); -} - -void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_sta= ck) -{ - if (mmap_is_legacy()) - mm->get_unmapped_area =3D arch_get_unmapped_area; - else - mm->get_unmapped_area =3D arch_get_unmapped_area_topdown; - - arch_pick_mmap_base(&mm->mmap_base, &mm->mmap_legacy_base, - arch_rnd(mmap64_rnd_bits), task_size_64bit(0), - rlim_stack); - -#ifdef CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES - /* - * The mmap syscall mapping base decision depends solely on the - * syscall type (64-bit or compat). This applies for 64bit - * applications and 32bit applications. The 64bit syscall uses - * mmap_base, the compat syscall uses mmap_compat_base. - */ - arch_pick_mmap_base(&mm->mmap_compat_base, &mm->mmap_compat_legacy_base= , - arch_rnd(mmap32_rnd_bits), task_size_32bit(), - rlim_stack); -#endif -} - unsigned long get_mmap_base(int is_legacy) { struct mm_struct *mm =3D current->mm; diff --git a/include/linux/compat.h b/include/linux/compat.h index 1c758b0e0359..0f7cc94f9b3f 100644 --- a/include/linux/compat.h +++ b/include/linux/compat.h @@ -946,6 +946,10 @@ static inline bool in_compat_syscall(void) { return = false; } =20 #endif /* CONFIG_COMPAT */ =20 +#ifndef CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES +static inline bool in_32bit_syscall(void) { return false; } +#endif + #define BITS_PER_COMPAT_LONG (8*sizeof(compat_long_t)) =20 #define BITS_TO_COMPAT_LONGS(bits) DIV_ROUND_UP(bits, BITS_PER_COMPAT_LO= NG) diff --git a/mm/util.c b/mm/util.c index 4ac87f1b30f1..8932388c96a3 100644 --- a/mm/util.c +++ b/mm/util.c @@ -357,8 +357,9 @@ unsigned long arch_mmap_rnd(void) { unsigned long rnd; =20 -#ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS - if (is_compat_task()) +#if defined(CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS) \ + || defined(CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES) + if (is_compat_task() || in_32bit_syscall()) rnd =3D get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1); else #endif /* CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS */ @@ -413,13 +414,24 @@ void arch_pick_mmap_layout(struct mm_struct *mm, st= ruct rlimit *rlim_stack) if (current->flags & PF_RANDOMIZE) random_factor =3D arch_mmap_rnd(); =20 + mm->mmap_legacy_base =3D TASK_UNMAPPED_BASE + random_factor; if (mmap_is_legacy(rlim_stack)) { - mm->mmap_base =3D TASK_UNMAPPED_BASE + random_factor; + mm->mmap_base =3D mm->mmap_legacy_base; mm->get_unmapped_area =3D arch_get_unmapped_area; } else { mm->mmap_base =3D mmap_base(random_factor, rlim_stack); mm->get_unmapped_area =3D arch_get_unmapped_area_topdown; } + +#ifdef CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES + if (mmap_is_legacy(rlim_stack)) { + mm->mmap_compat_legacy_base =3D + TASK_UNMAPPED_COMPAT_BASE + random_factor; + mm->mmap_compat_base =3D mm->mmap_compat_legacy_base; + } else { + mm->mmap_compat_base =3D mmap_base(random_factor, rlim_stack); + } +#endif } #elif defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT) void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_sta= ck) --=20 2.30.2