From: Ard Biesheuvel <ard.biesheuvel@linaro.org> To: Laura Abbott <labbott@fedoraproject.org> Cc: Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will.deacon@arm.com>, Mark Rutland <mark.rutland@arm.com>, Kees Cook <keescook@chromium.com>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org> Subject: Re: [PATCH] arm64: Allow vmalloc regions to be set with set_memory_* Date: Wed, 13 Jan 2016 17:10:31 +0100 [thread overview] Message-ID: <CAKv+Gu-73QKAsFQCa=yO5+=DihLXp_AKYyY6QRTVM4nuDH=-8g@mail.gmail.com> (raw) In-Reply-To: <CAKv+Gu_A1C9hXgqrYDekoy1YHaRXi_mUF-kYx-TqsOBkWMVjmQ@mail.gmail.com> On 13 January 2016 at 15:03, Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote: > On 12 January 2016 at 22:46, Laura Abbott <labbott@fedoraproject.org> wrote: >> >> The range of set_memory_* is currently restricted to the module address >> range because of difficulties in breaking down larger block sizes. >> vmalloc maps PAGE_SIZE pages so it is safe to use as well. Update the >> function ranges and add a comment explaining why the range is restricted >> the way it is. >> >> Signed-off-by: Laura Abbott <labbott@fedoraproject.org> >> --- >> This should let the protections for the eBPF work as expected, I don't >> know if there is some sort of self test for thatL. > > > This is going to conflict with my KASLR implementation, since it puts > the kernel image right in the middle of the vmalloc area, and the > kernel is obviously mapped with block mappings. In fact, I am > proposing enabling huge-vmap for arm64 as well, since it seems an > improvement generally, but also specifically allows me to unmap the > __init section using the generic vunmap code (remove_vm_area). But in > general, I think the assumption that the whole vmalloc area is mapped > using pages is not tenable. > > AFAICT, vmalloc still use pages exclusively even with huge-vmap (but > ioremap does not). So perhaps it would make sense to check for the > VM_ALLOC bit in the VMA flags (which I will not set for the kernel > regions either) > Something along these lines, perhaps? diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c index 3571c7309c5e..bda0a776c58e 100644 --- a/arch/arm64/mm/pageattr.c +++ b/arch/arm64/mm/pageattr.c @@ -13,6 +13,7 @@ #include <linux/kernel.h> #include <linux/mm.h> #include <linux/module.h> +#include <linux/vmalloc.h> #include <linux/sched.h> #include <asm/pgtable.h> @@ -44,6 +45,7 @@ static int change_memory_common(unsigned long addr unsigned long end = start + size; int ret; struct page_change_data data; + struct vm_struct *area; if (!PAGE_ALIGNED(addr)) { start &= PAGE_MASK; @@ -51,10 +53,14 @@ static int change_memory_common(unsigned long addr, WARN_ON_ONCE(1); } - if (start < MODULES_VADDR || start >= MODULES_END) - return -EINVAL; - - if (end < MODULES_VADDR || end >= MODULES_END) + /* + * Check whether the [addr, addr + size) interval is entirely + * covered by precisely one VM area that has the VM_ALLOC flag set + */ + area = find_vm_area((void *)addr); + if (!area || + end > (unsigned long)area->addr + area->size || + !(area->flags & VM_ALLOC)) return -EINVAL; data.set_mask = set_mask; > >> --- >> arch/arm64/mm/pageattr.c | 25 +++++++++++++++++++++---- >> 1 file changed, 21 insertions(+), 4 deletions(-) >> >> diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c >> index 3571c73..274208e 100644 >> --- a/arch/arm64/mm/pageattr.c >> +++ b/arch/arm64/mm/pageattr.c >> @@ -36,6 +36,26 @@ static int change_page_range(pte_t *ptep, pgtable_t token, unsigned long addr, >> return 0; >> } >> >> +static bool validate_addr(unsigned long start, unsigned long end) >> +{ >> + /* >> + * This check explicitly excludes most kernel memory. Most kernel >> + * memory is mapped with a larger page size and breaking down the >> + * larger page size without causing TLB conflicts is very difficult. >> + * >> + * If you need to call set_memory_* on a range, the recommendation is >> + * to use vmalloc since that range is mapped with pages. >> + */ >> + if (start >= MODULES_VADDR && start < MODULES_END && >> + end >= MODULES_VADDR && end < MODULES_END) >> + return true; >> + >> + if (is_vmalloc_addr(start) && is_vmalloc_addr(end)) >> + return true; >> + >> + return false; >> +} >> + >> static int change_memory_common(unsigned long addr, int numpages, >> pgprot_t set_mask, pgprot_t clear_mask) >> { >> @@ -51,10 +71,7 @@ static int change_memory_common(unsigned long addr, int numpages, >> WARN_ON_ONCE(1); >> } >> >> - if (start < MODULES_VADDR || start >= MODULES_END) >> - return -EINVAL; >> - >> - if (end < MODULES_VADDR || end >= MODULES_END) >> + if (!validate_addr(start, end)) >> return -EINVAL; >> >> data.set_mask = set_mask; >> -- >> 2.5.0 >> >> >> _______________________________________________ >> linux-arm-kernel mailing list >> linux-arm-kernel@lists.infradead.org >> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
WARNING: multiple messages have this Message-ID (diff)
From: ard.biesheuvel@linaro.org (Ard Biesheuvel) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH] arm64: Allow vmalloc regions to be set with set_memory_* Date: Wed, 13 Jan 2016 17:10:31 +0100 [thread overview] Message-ID: <CAKv+Gu-73QKAsFQCa=yO5+=DihLXp_AKYyY6QRTVM4nuDH=-8g@mail.gmail.com> (raw) In-Reply-To: <CAKv+Gu_A1C9hXgqrYDekoy1YHaRXi_mUF-kYx-TqsOBkWMVjmQ@mail.gmail.com> On 13 January 2016 at 15:03, Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote: > On 12 January 2016 at 22:46, Laura Abbott <labbott@fedoraproject.org> wrote: >> >> The range of set_memory_* is currently restricted to the module address >> range because of difficulties in breaking down larger block sizes. >> vmalloc maps PAGE_SIZE pages so it is safe to use as well. Update the >> function ranges and add a comment explaining why the range is restricted >> the way it is. >> >> Signed-off-by: Laura Abbott <labbott@fedoraproject.org> >> --- >> This should let the protections for the eBPF work as expected, I don't >> know if there is some sort of self test for thatL. > > > This is going to conflict with my KASLR implementation, since it puts > the kernel image right in the middle of the vmalloc area, and the > kernel is obviously mapped with block mappings. In fact, I am > proposing enabling huge-vmap for arm64 as well, since it seems an > improvement generally, but also specifically allows me to unmap the > __init section using the generic vunmap code (remove_vm_area). But in > general, I think the assumption that the whole vmalloc area is mapped > using pages is not tenable. > > AFAICT, vmalloc still use pages exclusively even with huge-vmap (but > ioremap does not). So perhaps it would make sense to check for the > VM_ALLOC bit in the VMA flags (which I will not set for the kernel > regions either) > Something along these lines, perhaps? diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c index 3571c7309c5e..bda0a776c58e 100644 --- a/arch/arm64/mm/pageattr.c +++ b/arch/arm64/mm/pageattr.c @@ -13,6 +13,7 @@ #include <linux/kernel.h> #include <linux/mm.h> #include <linux/module.h> +#include <linux/vmalloc.h> #include <linux/sched.h> #include <asm/pgtable.h> @@ -44,6 +45,7 @@ static int change_memory_common(unsigned long addr unsigned long end = start + size; int ret; struct page_change_data data; + struct vm_struct *area; if (!PAGE_ALIGNED(addr)) { start &= PAGE_MASK; @@ -51,10 +53,14 @@ static int change_memory_common(unsigned long addr, WARN_ON_ONCE(1); } - if (start < MODULES_VADDR || start >= MODULES_END) - return -EINVAL; - - if (end < MODULES_VADDR || end >= MODULES_END) + /* + * Check whether the [addr, addr + size) interval is entirely + * covered by precisely one VM area that has the VM_ALLOC flag set + */ + area = find_vm_area((void *)addr); + if (!area || + end > (unsigned long)area->addr + area->size || + !(area->flags & VM_ALLOC)) return -EINVAL; data.set_mask = set_mask; > >> --- >> arch/arm64/mm/pageattr.c | 25 +++++++++++++++++++++---- >> 1 file changed, 21 insertions(+), 4 deletions(-) >> >> diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c >> index 3571c73..274208e 100644 >> --- a/arch/arm64/mm/pageattr.c >> +++ b/arch/arm64/mm/pageattr.c >> @@ -36,6 +36,26 @@ static int change_page_range(pte_t *ptep, pgtable_t token, unsigned long addr, >> return 0; >> } >> >> +static bool validate_addr(unsigned long start, unsigned long end) >> +{ >> + /* >> + * This check explicitly excludes most kernel memory. Most kernel >> + * memory is mapped with a larger page size and breaking down the >> + * larger page size without causing TLB conflicts is very difficult. >> + * >> + * If you need to call set_memory_* on a range, the recommendation is >> + * to use vmalloc since that range is mapped with pages. >> + */ >> + if (start >= MODULES_VADDR && start < MODULES_END && >> + end >= MODULES_VADDR && end < MODULES_END) >> + return true; >> + >> + if (is_vmalloc_addr(start) && is_vmalloc_addr(end)) >> + return true; >> + >> + return false; >> +} >> + >> static int change_memory_common(unsigned long addr, int numpages, >> pgprot_t set_mask, pgprot_t clear_mask) >> { >> @@ -51,10 +71,7 @@ static int change_memory_common(unsigned long addr, int numpages, >> WARN_ON_ONCE(1); >> } >> >> - if (start < MODULES_VADDR || start >= MODULES_END) >> - return -EINVAL; >> - >> - if (end < MODULES_VADDR || end >= MODULES_END) >> + if (!validate_addr(start, end)) >> return -EINVAL; >> >> data.set_mask = set_mask; >> -- >> 2.5.0 >> >> >> _______________________________________________ >> linux-arm-kernel mailing list >> linux-arm-kernel at lists.infradead.org >> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2016-01-13 16:10 UTC|newest] Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-01-12 21:46 [PATCH] arm64: Allow vmalloc regions to be set with set_memory_* Laura Abbott 2016-01-12 21:46 ` Laura Abbott 2016-01-13 0:01 ` Alexei Starovoitov 2016-01-13 0:01 ` Alexei Starovoitov 2016-01-13 0:31 ` Daniel Borkmann 2016-01-13 0:31 ` Daniel Borkmann 2016-01-13 14:03 ` Ard Biesheuvel 2016-01-13 14:03 ` Ard Biesheuvel 2016-01-13 16:10 ` Ard Biesheuvel [this message] 2016-01-13 16:10 ` Ard Biesheuvel 2016-01-14 23:01 ` Laura Abbott 2016-01-14 23:01 ` Laura Abbott 2016-01-18 11:56 ` Mark Rutland 2016-01-18 11:56 ` Mark Rutland 2016-01-28 1:47 ` Xishi Qiu 2016-01-28 1:47 ` Xishi Qiu 2016-01-28 10:51 ` Mark Rutland 2016-01-28 10:51 ` Mark Rutland 2016-01-28 11:47 ` Xishi Qiu 2016-01-28 11:47 ` Xishi Qiu 2016-01-28 14:27 ` Mark Rutland 2016-01-28 14:27 ` Mark Rutland 2016-01-29 1:21 ` Xishi Qiu 2016-01-29 1:21 ` Xishi Qiu 2016-01-29 11:02 ` Mark Rutland 2016-01-29 11:02 ` Mark Rutland 2016-01-30 2:48 ` Xishi Qiu 2016-01-30 2:48 ` Xishi Qiu 2016-02-03 13:43 ` Mark Rutland 2016-02-03 13:43 ` Mark Rutland 2016-01-18 14:01 [PATCH] arm64: allow " Ard Biesheuvel 2016-01-18 15:05 ` Mark Rutland 2016-01-28 15:08 ` Will Deacon 2016-01-28 16:40 ` Ard Biesheuvel 2016-01-28 16:43 ` Ard Biesheuvel 2016-01-28 18:10 ` Will Deacon 2016-01-28 19:07 ` Ard Biesheuvel
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