arch/sparc/vdso/vma.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Set up the VMAs to tell the VM about the vDSO.
   4  * Copyright 2007 Andi Kleen, SUSE Labs.
   5  */
   6
   7 /*
   8  * Copyright (c) 2017 Oracle and/or its affiliates. All rights reserved.
   9  */
  10
  11 #include <linux/mm.h>
  12 #include <linux/err.h>
  13 #include <linux/sched.h>
  14 #include <linux/slab.h>
  15 #include <linux/init.h>
  16 #include <linux/linkage.h>
  17 #include <linux/random.h>
  18 #include <linux/elf.h>
  19 #include <asm/cacheflush.h>
  20 #include <asm/spitfire.h>
  21 #include <asm/vdso.h>
  22 #include <asm/vvar.h>
  23 #include <asm/page.h>
  24
  25 unsigned int __read_mostly vdso_enabled = 1;
  26
  27 static struct vm_special_mapping vvar_mapping = {
  28         .name = "[vvar]"
  29 };
  30
  31 #ifdef  CONFIG_SPARC64
  32 static struct vm_special_mapping vdso_mapping64 = {
  33         .name = "[vdso]"
  34 };
  35 #endif
  36
  37 #ifdef CONFIG_COMPAT
  38 static struct vm_special_mapping vdso_mapping32 = {
  39         .name = "[vdso]"
  40 };
  41 #endif
  42
  43 struct vvar_data *vvar_data;
  44
  45 struct vdso_elfinfo32 {
  46         Elf32_Ehdr      *hdr;
  47         Elf32_Sym       *dynsym;
  48         unsigned long   dynsymsize;
  49         const char      *dynstr;
  50         unsigned long   text;
  51 };
  52
  53 struct vdso_elfinfo64 {
  54         Elf64_Ehdr      *hdr;
  55         Elf64_Sym       *dynsym;
  56         unsigned long   dynsymsize;
  57         const char      *dynstr;
  58         unsigned long   text;
  59 };
  60
  61 struct vdso_elfinfo {
  62         union {
  63                 struct vdso_elfinfo32 elf32;
  64                 struct vdso_elfinfo64 elf64;
  65         } u;
  66 };
  67
  68 static void *one_section64(struct vdso_elfinfo64 *e, const char *name,
  69                            unsigned long *size)
  70 {
  71         const char *snames;
  72         Elf64_Shdr *shdrs;
  73         unsigned int i;
  74
  75         shdrs = (void *)e->hdr + e->hdr->e_shoff;
  76         snames = (void *)e->hdr + shdrs[e->hdr->e_shstrndx].sh_offset;
  77         for (i = 1; i < e->hdr->e_shnum; i++) {
  78                 if (!strcmp(snames+shdrs[i].sh_name, name)) {
  79                         if (size)
  80                                 *size = shdrs[i].sh_size;
  81                         return (void *)e->hdr + shdrs[i].sh_offset;
  82                 }
  83         }
  84         return NULL;
  85 }
  86
  87 static int find_sections64(const struct vdso_image *image, struct vdso_elfinfo *_e)
  88 {
  89         struct vdso_elfinfo64 *e = &_e->u.elf64;
  90
  91         e->hdr = image->data;
  92         e->dynsym = one_section64(e, ".dynsym", &e->dynsymsize);
  93         e->dynstr = one_section64(e, ".dynstr", NULL);
  94
  95         if (!e->dynsym || !e->dynstr) {
  96                 pr_err("VDSO64: Missing symbol sections.\n");
  97                 return -ENODEV;
  98         }
  99         return 0;
 100 }
 101
 102 static Elf64_Sym *find_sym64(const struct vdso_elfinfo64 *e, const char *name)
 103 {
 104         unsigned int i;
 105
 106         for (i = 0; i < (e->dynsymsize / sizeof(Elf64_Sym)); i++) {
 107                 Elf64_Sym *s = &e->dynsym[i];
 108                 if (s->st_name == 0)
 109                         continue;
 110                 if (!strcmp(e->dynstr + s->st_name, name))
 111                         return s;
 112         }
 113         return NULL;
 114 }
 115
 116 static int patchsym64(struct vdso_elfinfo *_e, const char *orig,
 117                       const char *new)
 118 {
 119         struct vdso_elfinfo64 *e = &_e->u.elf64;
 120         Elf64_Sym *osym = find_sym64(e, orig);
 121         Elf64_Sym *nsym = find_sym64(e, new);
 122
 123         if (!nsym || !osym) {
 124                 pr_err("VDSO64: Missing symbols.\n");
 125                 return -ENODEV;
 126         }
 127         osym->st_value = nsym->st_value;
 128         osym->st_size = nsym->st_size;
 129         osym->st_info = nsym->st_info;
 130         osym->st_other = nsym->st_other;
 131         osym->st_shndx = nsym->st_shndx;
 132
 133         return 0;
 134 }
 135
 136 static void *one_section32(struct vdso_elfinfo32 *e, const char *name,
 137                            unsigned long *size)
 138 {
 139         const char *snames;
 140         Elf32_Shdr *shdrs;
 141         unsigned int i;
 142
 143         shdrs = (void *)e->hdr + e->hdr->e_shoff;
 144         snames = (void *)e->hdr + shdrs[e->hdr->e_shstrndx].sh_offset;
 145         for (i = 1; i < e->hdr->e_shnum; i++) {
 146                 if (!strcmp(snames+shdrs[i].sh_name, name)) {
 147                         if (size)
 148                                 *size = shdrs[i].sh_size;
 149                         return (void *)e->hdr + shdrs[i].sh_offset;
 150                 }
 151         }
 152         return NULL;
 153 }
 154
 155 static int find_sections32(const struct vdso_image *image, struct vdso_elfinfo *_e)
 156 {
 157         struct vdso_elfinfo32 *e = &_e->u.elf32;
 158
 159         e->hdr = image->data;
 160         e->dynsym = one_section32(e, ".dynsym", &e->dynsymsize);
 161         e->dynstr = one_section32(e, ".dynstr", NULL);
 162
 163         if (!e->dynsym || !e->dynstr) {
 164                 pr_err("VDSO32: Missing symbol sections.\n");
 165                 return -ENODEV;
 166         }
 167         return 0;
 168 }
 169
 170 static Elf32_Sym *find_sym32(const struct vdso_elfinfo32 *e, const char *name)
 171 {
 172         unsigned int i;
 173
 174         for (i = 0; i < (e->dynsymsize / sizeof(Elf32_Sym)); i++) {
 175                 Elf32_Sym *s = &e->dynsym[i];
 176                 if (s->st_name == 0)
 177                         continue;
 178                 if (!strcmp(e->dynstr + s->st_name, name))
 179                         return s;
 180         }
 181         return NULL;
 182 }
 183
 184 static int patchsym32(struct vdso_elfinfo *_e, const char *orig,
 185                       const char *new)
 186 {
 187         struct vdso_elfinfo32 *e = &_e->u.elf32;
 188         Elf32_Sym *osym = find_sym32(e, orig);
 189         Elf32_Sym *nsym = find_sym32(e, new);
 190
 191         if (!nsym || !osym) {
 192                 pr_err("VDSO32: Missing symbols.\n");
 193                 return -ENODEV;
 194         }
 195         osym->st_value = nsym->st_value;
 196         osym->st_size = nsym->st_size;
 197         osym->st_info = nsym->st_info;
 198         osym->st_other = nsym->st_other;
 199         osym->st_shndx = nsym->st_shndx;
 200
 201         return 0;
 202 }
 203
 204 static int find_sections(const struct vdso_image *image, struct vdso_elfinfo *e,
 205                          bool elf64)
 206 {
 207         if (elf64)
 208                 return find_sections64(image, e);
 209         else
 210                 return find_sections32(image, e);
 211 }
 212
 213 static int patch_one_symbol(struct vdso_elfinfo *e, const char *orig,
 214                             const char *new_target, bool elf64)
 215 {
 216         if (elf64)
 217                 return patchsym64(e, orig, new_target);
 218         else
 219                 return patchsym32(e, orig, new_target);
 220 }
 221
 222 static int stick_patch(const struct vdso_image *image, struct vdso_elfinfo *e, bool elf64)
 223 {
 224         int err;
 225
 226         err = find_sections(image, e, elf64);
 227         if (err)
 228                 return err;
 229
 230         err = patch_one_symbol(e,
 231                                "__vdso_gettimeofday",
 232                                "__vdso_gettimeofday_stick", elf64);
 233         if (err)
 234                 return err;
 235
 236         return patch_one_symbol(e,
 237                                 "__vdso_clock_gettime",
 238                                 "__vdso_clock_gettime_stick", elf64);
 239         return 0;
 240 }
 241
 242 /*
 243  * Allocate pages for the vdso and vvar, and copy in the vdso text from the
 244  * kernel image.
 245  */
 246 static int __init init_vdso_image(const struct vdso_image *image,
 247                                   struct vm_special_mapping *vdso_mapping,
 248                                   bool elf64)
 249 {
 250         int cnpages = (image->size) / PAGE_SIZE;
 251         struct page *dp, **dpp = NULL;
 252         struct page *cp, **cpp = NULL;
 253         struct vdso_elfinfo ei;
 254         int i, dnpages = 0;
 255
 256         if (tlb_type != spitfire) {
 257                 int err = stick_patch(image, &ei, elf64);
 258                 if (err)
 259                         return err;
 260         }
 261
 262         /*
 263          * First, the vdso text.  This is initialied data, an integral number of
 264          * pages long.
 265          */
 266         if (WARN_ON(image->size % PAGE_SIZE != 0))
 267                 goto oom;
 268
 269         cpp = kcalloc(cnpages, sizeof(struct page *), GFP_KERNEL);
 270         vdso_mapping->pages = cpp;
 271
 272         if (!cpp)
 273                 goto oom;
 274
 275         for (i = 0; i < cnpages; i++) {
 276                 cp = alloc_page(GFP_KERNEL);
 277                 if (!cp)
 278                         goto oom;
 279                 cpp[i] = cp;
 280                 copy_page(page_address(cp), image->data + i * PAGE_SIZE);
 281         }
 282
 283         /*
 284          * Now the vvar page.  This is uninitialized data.
 285          */
 286
 287         if (vvar_data == NULL) {
 288                 dnpages = (sizeof(struct vvar_data) / PAGE_SIZE) + 1;
 289                 if (WARN_ON(dnpages != 1))
 290                         goto oom;
 291                 dpp = kcalloc(dnpages, sizeof(struct page *), GFP_KERNEL);
 292                 vvar_mapping.pages = dpp;
 293
 294                 if (!dpp)
 295                         goto oom;
 296
 297                 dp = alloc_page(GFP_KERNEL);
 298                 if (!dp)
 299                         goto oom;
 300
 301                 dpp[0] = dp;
 302                 vvar_data = page_address(dp);
 303                 memset(vvar_data, 0, PAGE_SIZE);
 304
 305                 vvar_data->seq = 0;
 306         }
 307
 308         return 0;
 309  oom:
 310         if (cpp != NULL) {
 311                 for (i = 0; i < cnpages; i++) {
 312                         if (cpp[i] != NULL)
 313                                 __free_page(cpp[i]);
 314                 }
 315                 kfree(cpp);
 316                 vdso_mapping->pages = NULL;
 317         }
 318
 319         if (dpp != NULL) {
 320                 for (i = 0; i < dnpages; i++) {
 321                         if (dpp[i] != NULL)
 322                                 __free_page(dpp[i]);
 323                 }
 324                 kfree(dpp);
 325                 vvar_mapping.pages = NULL;
 326         }
 327
 328         pr_warn("Cannot allocate vdso\n");
 329         vdso_enabled = 0;
 330         return -ENOMEM;
 331 }
 332
 333 static int __init init_vdso(void)
 334 {
 335         int err = 0;
 336 #ifdef CONFIG_SPARC64
 337         err = init_vdso_image(&vdso_image_64_builtin, &vdso_mapping64, true);
 338         if (err)
 339                 return err;
 340 #endif
 341
 342 #ifdef CONFIG_COMPAT
 343         err = init_vdso_image(&vdso_image_32_builtin, &vdso_mapping32, false);
 344 #endif
 345         return err;
 346
 347 }
 348 subsys_initcall(init_vdso);
 349
 350 struct linux_binprm;
 351
 352 /* Shuffle the vdso up a bit, randomly. */
 353 static unsigned long vdso_addr(unsigned long start, unsigned int len)
 354 {
 355         unsigned int offset;
 356
 357         /* This loses some more bits than a modulo, but is cheaper */
 358         offset = get_random_u32_below(PTRS_PER_PTE);
 359         return start + (offset << PAGE_SHIFT);
 360 }
 361
 362 static int map_vdso(const struct vdso_image *image,
 363                 struct vm_special_mapping *vdso_mapping)
 364 {
 365         struct mm_struct *mm = current->mm;
 366         struct vm_area_struct *vma;
 367         unsigned long text_start, addr = 0;
 368         int ret = 0;
 369
 370         mmap_write_lock(mm);
 371
 372         /*
 373          * First, get an unmapped region: then randomize it, and make sure that
 374          * region is free.
 375          */
 376         if (current->flags & PF_RANDOMIZE) {
 377                 addr = get_unmapped_area(NULL, 0,
 378                                          image->size - image->sym_vvar_start,
 379                                          0, 0);
 380                 if (IS_ERR_VALUE(addr)) {
 381                         ret = addr;
 382                         goto up_fail;
 383                 }
 384                 addr = vdso_addr(addr, image->size - image->sym_vvar_start);
 385         }
 386         addr = get_unmapped_area(NULL, addr,
 387                                  image->size - image->sym_vvar_start, 0, 0);
 388         if (IS_ERR_VALUE(addr)) {
 389                 ret = addr;
 390                 goto up_fail;
 391         }
 392
 393         text_start = addr - image->sym_vvar_start;
 394         current->mm->context.vdso = (void __user *)text_start;
 395
 396         /*
 397          * MAYWRITE to allow gdb to COW and set breakpoints
 398          */
 399         vma = _install_special_mapping(mm,
 400                                        text_start,
 401                                        image->size,
 402                                        VM_READ|VM_EXEC|
 403                                        VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
 404                                        vdso_mapping);
 405
 406         if (IS_ERR(vma)) {
 407                 ret = PTR_ERR(vma);
 408                 goto up_fail;
 409         }
 410
 411         vma = _install_special_mapping(mm,
 412                                        addr,
 413                                        -image->sym_vvar_start,
 414                                        VM_READ|VM_MAYREAD,
 415                                        &vvar_mapping);
 416
 417         if (IS_ERR(vma)) {
 418                 ret = PTR_ERR(vma);
 419                 do_munmap(mm, text_start, image->size, NULL);
 420         }
 421
 422 up_fail:
 423         if (ret)
 424                 current->mm->context.vdso = NULL;
 425
 426         mmap_write_unlock(mm);
 427         return ret;
 428 }
 429
 430 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 431 {
 432
 433         if (!vdso_enabled)
 434                 return 0;
 435
 436 #if defined CONFIG_COMPAT
 437         if (!(is_32bit_task()))
 438                 return map_vdso(&vdso_image_64_builtin, &vdso_mapping64);
 439         else
 440                 return map_vdso(&vdso_image_32_builtin, &vdso_mapping32);
 441 #else
 442         return map_vdso(&vdso_image_64_builtin, &vdso_mapping64);
 443 #endif
 444
 445 }
 446
 447 static __init int vdso_setup(char *s)
 448 {
 449         int err;
 450         unsigned long val;
 451
 452         err = kstrtoul(s, 10, &val);
 453         if (!err)
 454                 vdso_enabled = val;
 455         return 1;
 456 }
 457 __setup("vdso=", vdso_setup);