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author | 2020-12-14 19:08:25 -0800 | |
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committer | 2020-12-15 12:13:41 -0800 | |
commit | 871402e05b24cb56bc69df47cff960d0e0d24267 (patch) | |
tree | f8235ea5b089ed3c9def2e9c6ed2df51d205e8d3 | |
parent | mremap: check if it's possible to split original vma (diff) | |
download | linux-871402e05b24cb56bc69df47cff960d0e0d24267.tar.gz linux-871402e05b24cb56bc69df47cff960d0e0d24267.tar.bz2 linux-871402e05b24cb56bc69df47cff960d0e0d24267.zip |
mm: forbid splitting special mappings
Don't allow splitting of vm_special_mapping's. It affects vdso/vvar
areas. Uprobes have only one page in xol_area so they aren't affected.
Those restrictions were enforced by checks in .mremap() callbacks.
Restrict resizing with generic .split() callback.
Link: https://lkml.kernel.org/r/20201013013416.390574-7-dima@arista.com
Signed-off-by: Dmitry Safonov <dima@arista.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Brian Geffon <bgeffon@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r-- | arch/arm/kernel/vdso.c | 9 | ||||
-rw-r--r-- | arch/arm64/kernel/vdso.c | 39 | ||||
-rw-r--r-- | arch/mips/vdso/genvdso.c | 4 | ||||
-rw-r--r-- | arch/s390/kernel/vdso.c | 11 | ||||
-rw-r--r-- | arch/x86/entry/vdso/vma.c | 17 | ||||
-rw-r--r-- | mm/mmap.c | 12 |
6 files changed, 16 insertions, 76 deletions
diff --git a/arch/arm/kernel/vdso.c b/arch/arm/kernel/vdso.c index fddd08a6e063..3408269d19c7 100644 --- a/arch/arm/kernel/vdso.c +++ b/arch/arm/kernel/vdso.c @@ -50,15 +50,6 @@ static const struct vm_special_mapping vdso_data_mapping = { static int vdso_mremap(const struct vm_special_mapping *sm, struct vm_area_struct *new_vma) { - unsigned long new_size = new_vma->vm_end - new_vma->vm_start; - unsigned long vdso_size; - - /* without VVAR page */ - vdso_size = (vdso_total_pages - 1) << PAGE_SHIFT; - - if (vdso_size != new_size) - return -EINVAL; - current->mm->context.vdso = new_vma->vm_start; return 0; diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c index debb8995d57f..cee5d04ea9ad 100644 --- a/arch/arm64/kernel/vdso.c +++ b/arch/arm64/kernel/vdso.c @@ -78,17 +78,9 @@ static union { } vdso_data_store __page_aligned_data; struct vdso_data *vdso_data = vdso_data_store.data; -static int __vdso_remap(enum vdso_abi abi, - const struct vm_special_mapping *sm, - struct vm_area_struct *new_vma) +static int vdso_mremap(const struct vm_special_mapping *sm, + struct vm_area_struct *new_vma) { - unsigned long new_size = new_vma->vm_end - new_vma->vm_start; - unsigned long vdso_size = vdso_info[abi].vdso_code_end - - vdso_info[abi].vdso_code_start; - - if (vdso_size != new_size) - return -EINVAL; - current->mm->context.vdso = (void *)new_vma->vm_start; return 0; @@ -219,17 +211,6 @@ static vm_fault_t vvar_fault(const struct vm_special_mapping *sm, return vmf_insert_pfn(vma, vmf->address, pfn); } -static int vvar_mremap(const struct vm_special_mapping *sm, - struct vm_area_struct *new_vma) -{ - unsigned long new_size = new_vma->vm_end - new_vma->vm_start; - - if (new_size != VVAR_NR_PAGES * PAGE_SIZE) - return -EINVAL; - - return 0; -} - static int __setup_additional_pages(enum vdso_abi abi, struct mm_struct *mm, struct linux_binprm *bprm, @@ -280,12 +261,6 @@ up_fail: /* * Create and map the vectors page for AArch32 tasks. */ -static int aarch32_vdso_mremap(const struct vm_special_mapping *sm, - struct vm_area_struct *new_vma) -{ - return __vdso_remap(VDSO_ABI_AA32, sm, new_vma); -} - enum aarch32_map { AA32_MAP_VECTORS, /* kuser helpers */ AA32_MAP_SIGPAGE, @@ -308,11 +283,10 @@ static struct vm_special_mapping aarch32_vdso_maps[] = { [AA32_MAP_VVAR] = { .name = "[vvar]", .fault = vvar_fault, - .mremap = vvar_mremap, }, [AA32_MAP_VDSO] = { .name = "[vdso]", - .mremap = aarch32_vdso_mremap, + .mremap = vdso_mremap, }, }; @@ -453,12 +427,6 @@ out: } #endif /* CONFIG_COMPAT */ -static int vdso_mremap(const struct vm_special_mapping *sm, - struct vm_area_struct *new_vma) -{ - return __vdso_remap(VDSO_ABI_AA64, sm, new_vma); -} - enum aarch64_map { AA64_MAP_VVAR, AA64_MAP_VDSO, @@ -468,7 +436,6 @@ static struct vm_special_mapping aarch64_vdso_maps[] __ro_after_init = { [AA64_MAP_VVAR] = { .name = "[vvar]", .fault = vvar_fault, - .mremap = vvar_mremap, }, [AA64_MAP_VDSO] = { .name = "[vdso]", diff --git a/arch/mips/vdso/genvdso.c b/arch/mips/vdso/genvdso.c index abb06ae04b40..09e30eb4be86 100644 --- a/arch/mips/vdso/genvdso.c +++ b/arch/mips/vdso/genvdso.c @@ -263,10 +263,6 @@ int main(int argc, char **argv) fprintf(out_file, " const struct vm_special_mapping *sm,\n"); fprintf(out_file, " struct vm_area_struct *new_vma)\n"); fprintf(out_file, "{\n"); - fprintf(out_file, " unsigned long new_size =\n"); - fprintf(out_file, " new_vma->vm_end - new_vma->vm_start;\n"); - fprintf(out_file, " if (vdso_image.size != new_size)\n"); - fprintf(out_file, " return -EINVAL;\n"); fprintf(out_file, " current->mm->context.vdso =\n"); fprintf(out_file, " (void *)(new_vma->vm_start);\n"); fprintf(out_file, " return 0;\n"); diff --git a/arch/s390/kernel/vdso.c b/arch/s390/kernel/vdso.c index f9da5b149141..6c9ec9521203 100644 --- a/arch/s390/kernel/vdso.c +++ b/arch/s390/kernel/vdso.c @@ -61,17 +61,8 @@ static vm_fault_t vdso_fault(const struct vm_special_mapping *sm, static int vdso_mremap(const struct vm_special_mapping *sm, struct vm_area_struct *vma) { - unsigned long vdso_pages; - - vdso_pages = vdso64_pages; - - if ((vdso_pages << PAGE_SHIFT) != vma->vm_end - vma->vm_start) - return -EINVAL; - - if (WARN_ON_ONCE(current->mm != vma->vm_mm)) - return -EFAULT; - current->mm->context.vdso_base = vma->vm_start; + return 0; } diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c index 9185cb1d13b9..0c942b31825d 100644 --- a/arch/x86/entry/vdso/vma.c +++ b/arch/x86/entry/vdso/vma.c @@ -89,30 +89,14 @@ static void vdso_fix_landing(const struct vdso_image *image, static int vdso_mremap(const struct vm_special_mapping *sm, struct vm_area_struct *new_vma) { - unsigned long new_size = new_vma->vm_end - new_vma->vm_start; const struct vdso_image *image = current->mm->context.vdso_image; - if (image->size != new_size) - return -EINVAL; - vdso_fix_landing(image, new_vma); current->mm->context.vdso = (void __user *)new_vma->vm_start; return 0; } -static int vvar_mremap(const struct vm_special_mapping *sm, - struct vm_area_struct *new_vma) -{ - const struct vdso_image *image = new_vma->vm_mm->context.vdso_image; - unsigned long new_size = new_vma->vm_end - new_vma->vm_start; - - if (new_size != -image->sym_vvar_start) - return -EINVAL; - - return 0; -} - #ifdef CONFIG_TIME_NS static struct page *find_timens_vvar_page(struct vm_area_struct *vma) { @@ -252,7 +236,6 @@ static const struct vm_special_mapping vdso_mapping = { static const struct vm_special_mapping vvar_mapping = { .name = "[vvar]", .fault = vvar_fault, - .mremap = vvar_mremap, }; /* diff --git a/mm/mmap.c b/mm/mmap.c index 886de799e7d2..10598e5d4757 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -3422,6 +3422,17 @@ static int special_mapping_mremap(struct vm_area_struct *new_vma, return 0; } +static int special_mapping_split(struct vm_area_struct *vma, unsigned long addr) +{ + /* + * Forbid splitting special mappings - kernel has expectations over + * the number of pages in mapping. Together with VM_DONTEXPAND + * the size of vma should stay the same over the special mapping's + * lifetime. + */ + return -EINVAL; +} + static const struct vm_operations_struct special_mapping_vmops = { .close = special_mapping_close, .fault = special_mapping_fault, @@ -3429,6 +3440,7 @@ static const struct vm_operations_struct special_mapping_vmops = { .name = special_mapping_name, /* vDSO code relies that VVAR can't be accessed remotely */ .access = NULL, + .may_split = special_mapping_split, }; static const struct vm_operations_struct legacy_special_mapping_vmops = { |