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https://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf.git
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51d6ca373f
Extend the generic vDSO data storage with a page for the random state data. The random state data is stored in a dedicated page, as the existing storage page is only meant for time-related, time-namespace-aware data. This simplifies to access logic to not need to handle time namespaces anymore and also frees up more space in the time-related page. In case further generic vDSO data store is required it can be added to the random state page. Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/all/20250204-vdso-store-rng-v3-6-13a4669dfc8c@linutronix.de
118 lines
3.3 KiB
C
118 lines
3.3 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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#include <linux/linkage.h>
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#include <linux/mmap_lock.h>
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#include <linux/mm.h>
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#include <linux/time_namespace.h>
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#include <linux/types.h>
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#include <linux/vdso_datastore.h>
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#include <vdso/datapage.h>
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/*
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* The vDSO data page.
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*/
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#ifdef CONFIG_HAVE_GENERIC_VDSO
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static union vdso_data_store vdso_time_data_store __page_aligned_data;
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struct vdso_time_data *vdso_k_time_data = vdso_time_data_store.data;
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static_assert(sizeof(vdso_time_data_store) == PAGE_SIZE);
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#endif /* CONFIG_HAVE_GENERIC_VDSO */
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#ifdef CONFIG_VDSO_GETRANDOM
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static union {
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struct vdso_rng_data data;
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u8 page[PAGE_SIZE];
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} vdso_rng_data_store __page_aligned_data;
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struct vdso_rng_data *vdso_k_rng_data = &vdso_rng_data_store.data;
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static_assert(sizeof(vdso_rng_data_store) == PAGE_SIZE);
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#endif /* CONFIG_VDSO_GETRANDOM */
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static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
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struct vm_area_struct *vma, struct vm_fault *vmf)
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{
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struct page *timens_page = find_timens_vvar_page(vma);
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unsigned long addr, pfn;
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vm_fault_t err;
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switch (vmf->pgoff) {
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case VDSO_TIME_PAGE_OFFSET:
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if (!IS_ENABLED(CONFIG_HAVE_GENERIC_VDSO))
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return VM_FAULT_SIGBUS;
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pfn = __phys_to_pfn(__pa_symbol(vdso_k_time_data));
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if (timens_page) {
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/*
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* Fault in VVAR page too, since it will be accessed
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* to get clock data anyway.
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*/
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addr = vmf->address + VDSO_TIMENS_PAGE_OFFSET * PAGE_SIZE;
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err = vmf_insert_pfn(vma, addr, pfn);
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if (unlikely(err & VM_FAULT_ERROR))
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return err;
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pfn = page_to_pfn(timens_page);
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}
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break;
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case VDSO_TIMENS_PAGE_OFFSET:
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/*
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* If a task belongs to a time namespace then a namespace
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* specific VVAR is mapped with the VVAR_DATA_PAGE_OFFSET and
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* the real VVAR page is mapped with the VVAR_TIMENS_PAGE_OFFSET
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* offset.
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* See also the comment near timens_setup_vdso_data().
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*/
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if (!IS_ENABLED(CONFIG_TIME_NS) || !timens_page)
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return VM_FAULT_SIGBUS;
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pfn = __phys_to_pfn(__pa_symbol(vdso_k_time_data));
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break;
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case VDSO_RNG_PAGE_OFFSET:
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if (!IS_ENABLED(CONFIG_VDSO_GETRANDOM))
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return VM_FAULT_SIGBUS;
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pfn = __phys_to_pfn(__pa_symbol(vdso_k_rng_data));
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break;
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default:
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return VM_FAULT_SIGBUS;
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}
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return vmf_insert_pfn(vma, vmf->address, pfn);
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}
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const struct vm_special_mapping vdso_vvar_mapping = {
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.name = "[vvar]",
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.fault = vvar_fault,
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};
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struct vm_area_struct *vdso_install_vvar_mapping(struct mm_struct *mm, unsigned long addr)
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{
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return _install_special_mapping(mm, addr, VDSO_NR_PAGES * PAGE_SIZE,
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VM_READ | VM_MAYREAD | VM_IO | VM_DONTDUMP | VM_PFNMAP,
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&vdso_vvar_mapping);
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}
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#ifdef CONFIG_TIME_NS
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/*
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* The vvar page layout depends on whether a task belongs to the root or
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* non-root time namespace. Whenever a task changes its namespace, the VVAR
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* page tables are cleared and then they will be re-faulted with a
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* corresponding layout.
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* See also the comment near timens_setup_vdso_data() for details.
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*/
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int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
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{
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struct mm_struct *mm = task->mm;
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struct vm_area_struct *vma;
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VMA_ITERATOR(vmi, mm, 0);
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mmap_read_lock(mm);
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for_each_vma(vmi, vma) {
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if (vma_is_special_mapping(vma, &vdso_vvar_mapping))
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zap_vma_pages(vma);
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}
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mmap_read_unlock(mm);
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return 0;
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}
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struct vdso_time_data *arch_get_vdso_data(void *vvar_page)
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{
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return (struct vdso_time_data *)vvar_page;
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}
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#endif
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