From: Dave Hansen Date: Fri, 12 Feb 2016 21:01:54 +0000 (-0800) Subject: mm/gup: Introduce get_user_pages_remote() X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=1e9877902dc7;p=linux.git mm/gup: Introduce get_user_pages_remote() For protection keys, we need to understand whether protections should be enforced in software or not. In general, we enforce protections when working on our own task, but not when on others. We call these "current" and "remote" operations. This patch introduces a new get_user_pages() variant: get_user_pages_remote() Which is a replacement for when get_user_pages() is called on non-current tsk/mm. We also introduce a new gup flag: FOLL_REMOTE which can be used for the "__" gup variants to get this new behavior. The uprobes is_trap_at_addr() location holds mmap_sem and calls get_user_pages(current->mm) on an instruction address. This makes it a pretty unique gup caller. Being an instruction access and also really originating from the kernel (vs. the app), I opted to consider this a 'remote' access where protection keys will not be enforced. Without protection keys, this patch should not change any behavior. Signed-off-by: Dave Hansen Reviewed-by: Thomas Gleixner Cc: Andrea Arcangeli Cc: Andrew Morton Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Hansen Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Kirill A. Shutemov Cc: Linus Torvalds Cc: Naoya Horiguchi Cc: Peter Zijlstra Cc: Rik van Riel Cc: Srikar Dronamraju Cc: Vlastimil Babka Cc: jack@suse.cz Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20160212210154.3F0E51EA@viggo.jf.intel.com Signed-off-by: Ingo Molnar --- diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem.c b/drivers/gpu/drm/etnaviv/etnaviv_gem.c index 4b519e4309b28..97d4457be8d26 100644 --- a/drivers/gpu/drm/etnaviv/etnaviv_gem.c +++ b/drivers/gpu/drm/etnaviv/etnaviv_gem.c @@ -753,9 +753,9 @@ static struct page **etnaviv_gem_userptr_do_get_pages( down_read(&mm->mmap_sem); while (pinned < npages) { - ret = get_user_pages(task, mm, ptr, npages - pinned, - !etnaviv_obj->userptr.ro, 0, - pvec + pinned, NULL); + ret = get_user_pages_remote(task, mm, ptr, npages - pinned, + !etnaviv_obj->userptr.ro, 0, + pvec + pinned, NULL); if (ret < 0) break; diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c index 59e45b3a69379..90dbf81212109 100644 --- a/drivers/gpu/drm/i915/i915_gem_userptr.c +++ b/drivers/gpu/drm/i915/i915_gem_userptr.c @@ -584,11 +584,11 @@ __i915_gem_userptr_get_pages_worker(struct work_struct *_work) down_read(&mm->mmap_sem); while (pinned < npages) { - ret = get_user_pages(work->task, mm, - obj->userptr.ptr + pinned * PAGE_SIZE, - npages - pinned, - !obj->userptr.read_only, 0, - pvec + pinned, NULL); + ret = get_user_pages_remote(work->task, mm, + obj->userptr.ptr + pinned * PAGE_SIZE, + npages - pinned, + !obj->userptr.read_only, 0, + pvec + pinned, NULL); if (ret < 0) break; diff --git a/drivers/infiniband/core/umem_odp.c b/drivers/infiniband/core/umem_odp.c index e69bf266049d0..75077a018675e 100644 --- a/drivers/infiniband/core/umem_odp.c +++ b/drivers/infiniband/core/umem_odp.c @@ -572,10 +572,10 @@ int ib_umem_odp_map_dma_pages(struct ib_umem *umem, u64 user_virt, u64 bcnt, * complex (and doesn't gain us much performance in most use * cases). */ - npages = get_user_pages(owning_process, owning_mm, user_virt, - gup_num_pages, - access_mask & ODP_WRITE_ALLOWED_BIT, 0, - local_page_list, NULL); + npages = get_user_pages_remote(owning_process, owning_mm, + user_virt, gup_num_pages, + access_mask & ODP_WRITE_ALLOWED_BIT, + 0, local_page_list, NULL); up_read(&owning_mm->mmap_sem); if (npages < 0) diff --git a/fs/exec.c b/fs/exec.c index dcd4ac7d3f1e7..d885b98b6a000 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -198,8 +198,12 @@ static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, return NULL; } #endif - ret = get_user_pages(current, bprm->mm, pos, - 1, write, 1, &page, NULL); + /* + * We are doing an exec(). 'current' is the process + * doing the exec and bprm->mm is the new process's mm. + */ + ret = get_user_pages_remote(current, bprm->mm, pos, 1, write, + 1, &page, NULL); if (ret <= 0) return NULL; diff --git a/include/linux/mm.h b/include/linux/mm.h index b1d4b8c7f7cdc..faf3b709eeadd 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1225,6 +1225,10 @@ long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, unsigned long start, unsigned long nr_pages, unsigned int foll_flags, struct page **pages, struct vm_area_struct **vmas, int *nonblocking); +long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm, + unsigned long start, unsigned long nr_pages, + int write, int force, struct page **pages, + struct vm_area_struct **vmas); long get_user_pages(struct task_struct *tsk, struct mm_struct *mm, unsigned long start, unsigned long nr_pages, int write, int force, struct page **pages, @@ -2170,6 +2174,7 @@ static inline struct page *follow_page(struct vm_area_struct *vma, #define FOLL_MIGRATION 0x400 /* wait for page to replace migration entry */ #define FOLL_TRIED 0x800 /* a retry, previous pass started an IO */ #define FOLL_MLOCK 0x1000 /* lock present pages */ +#define FOLL_REMOTE 0x2000 /* we are working on non-current tsk/mm */ typedef int (*pte_fn_t)(pte_t *pte, pgtable_t token, unsigned long addr, void *data); diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 0167679182c08..8eef5f55d3f0e 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -299,7 +299,7 @@ int uprobe_write_opcode(struct mm_struct *mm, unsigned long vaddr, retry: /* Read the page with vaddr into memory */ - ret = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &old_page, &vma); + ret = get_user_pages_remote(NULL, mm, vaddr, 1, 0, 1, &old_page, &vma); if (ret <= 0) return ret; @@ -1700,7 +1700,13 @@ static int is_trap_at_addr(struct mm_struct *mm, unsigned long vaddr) if (likely(result == 0)) goto out; - result = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &page, NULL); + /* + * The NULL 'tsk' here ensures that any faults that occur here + * will not be accounted to the task. 'mm' *is* current->mm, + * but we treat this as a 'remote' access since it is + * essentially a kernel access to the memory. + */ + result = get_user_pages_remote(NULL, mm, vaddr, 1, 0, 1, &page, NULL); if (result < 0) return result; diff --git a/mm/gup.c b/mm/gup.c index 7bf19ffa21999..36ca850936c9f 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -870,7 +870,7 @@ long get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm, EXPORT_SYMBOL(get_user_pages_unlocked); /* - * get_user_pages() - pin user pages in memory + * get_user_pages_remote() - pin user pages in memory * @tsk: the task_struct to use for page fault accounting, or * NULL if faults are not to be recorded. * @mm: mm_struct of target mm @@ -924,12 +924,29 @@ EXPORT_SYMBOL(get_user_pages_unlocked); * should use get_user_pages because it cannot pass * FAULT_FLAG_ALLOW_RETRY to handle_mm_fault. */ -long get_user_pages(struct task_struct *tsk, struct mm_struct *mm, - unsigned long start, unsigned long nr_pages, int write, - int force, struct page **pages, struct vm_area_struct **vmas) +long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm, + unsigned long start, unsigned long nr_pages, + int write, int force, struct page **pages, + struct vm_area_struct **vmas) { return __get_user_pages_locked(tsk, mm, start, nr_pages, write, force, - pages, vmas, NULL, false, FOLL_TOUCH); + pages, vmas, NULL, false, + FOLL_TOUCH | FOLL_REMOTE); +} +EXPORT_SYMBOL(get_user_pages_remote); + +/* + * This is the same as get_user_pages_remote() for the time + * being. + */ +long get_user_pages(struct task_struct *tsk, struct mm_struct *mm, + unsigned long start, unsigned long nr_pages, + int write, int force, struct page **pages, + struct vm_area_struct **vmas) +{ + return __get_user_pages_locked(tsk, mm, start, nr_pages, + write, force, pages, vmas, NULL, false, + FOLL_TOUCH); } EXPORT_SYMBOL(get_user_pages); diff --git a/mm/memory.c b/mm/memory.c index 38090ca37a08b..8bfbad0cca8ce 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3685,7 +3685,7 @@ static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, void *maddr; struct page *page = NULL; - ret = get_user_pages(tsk, mm, addr, 1, + ret = get_user_pages_remote(tsk, mm, addr, 1, write, 1, &page, &vma); if (ret <= 0) { #ifndef CONFIG_HAVE_IOREMAP_PROT diff --git a/mm/process_vm_access.c b/mm/process_vm_access.c index 5d453e58ddbf7..07514d41ebcc1 100644 --- a/mm/process_vm_access.c +++ b/mm/process_vm_access.c @@ -98,9 +98,14 @@ static int process_vm_rw_single_vec(unsigned long addr, int pages = min(nr_pages, max_pages_per_loop); size_t bytes; - /* Get the pages we're interested in */ - pages = get_user_pages_unlocked(task, mm, pa, pages, - vm_write, 0, process_pages); + /* + * Get the pages we're interested in. We must + * add FOLL_REMOTE because task/mm might not + * current/current->mm + */ + pages = __get_user_pages_unlocked(task, mm, pa, pages, + vm_write, 0, process_pages, + FOLL_REMOTE); if (pages <= 0) return -EFAULT; diff --git a/security/tomoyo/domain.c b/security/tomoyo/domain.c index 38651454ed08a..ade7c6cad172a 100644 --- a/security/tomoyo/domain.c +++ b/security/tomoyo/domain.c @@ -874,7 +874,14 @@ bool tomoyo_dump_page(struct linux_binprm *bprm, unsigned long pos, } /* Same with get_arg_page(bprm, pos, 0) in fs/exec.c */ #ifdef CONFIG_MMU - if (get_user_pages(current, bprm->mm, pos, 1, 0, 1, &page, NULL) <= 0) + /* + * This is called at execve() time in order to dig around + * in the argv/environment of the new proceess + * (represented by bprm). 'current' is the process doing + * the execve(). + */ + if (get_user_pages_remote(current, bprm->mm, pos, 1, + 0, 1, &page, NULL) <= 0) return false; #else page = bprm->page[pos / PAGE_SIZE]; diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c index 3531599224560..d604e87a510af 100644 --- a/virt/kvm/async_pf.c +++ b/virt/kvm/async_pf.c @@ -79,7 +79,13 @@ static void async_pf_execute(struct work_struct *work) might_sleep(); - get_user_pages_unlocked(NULL, mm, addr, 1, 1, 0, NULL); + /* + * This work is run asynchromously to the task which owns + * mm and might be done in another context, so we must + * use FOLL_REMOTE. + */ + __get_user_pages_unlocked(NULL, mm, addr, 1, 1, 0, NULL, FOLL_REMOTE); + kvm_async_page_present_sync(vcpu, apf); spin_lock(&vcpu->async_pf.lock);