95 lines
2.6 KiB
C
95 lines
2.6 KiB
C
/* AArch64 BTI functions.
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Copyright (C) 2020-2022 Free Software Foundation, Inc.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <unistd.h>
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#include <errno.h>
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#include <libintl.h>
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#include <ldsodefs.h>
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#include <sys/mman.h>
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/* See elf/dl-load.h. */
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#ifndef MAP_COPY
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# define MAP_COPY (MAP_PRIVATE | MAP_DENYWRITE)
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#endif
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/* Enable BTI protection for MAP. */
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void
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_dl_bti_protect (struct link_map *map, int fd)
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{
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const size_t pagesz = GLRO(dl_pagesize);
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const ElfW(Phdr) *phdr;
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for (phdr = map->l_phdr; phdr < &map->l_phdr[map->l_phnum]; ++phdr)
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if (phdr->p_type == PT_LOAD && (phdr->p_flags & PF_X))
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{
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size_t vstart = ALIGN_DOWN (phdr->p_vaddr, pagesz);
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size_t vend = ALIGN_UP (phdr->p_vaddr + phdr->p_filesz, pagesz);
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off_t off = ALIGN_DOWN (phdr->p_offset, pagesz);
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void *start = (void *) (vstart + map->l_addr);
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size_t len = vend - vstart;
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unsigned prot = PROT_EXEC | PROT_BTI;
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if (phdr->p_flags & PF_R)
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prot |= PROT_READ;
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if (phdr->p_flags & PF_W)
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prot |= PROT_WRITE;
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if (fd == -1)
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/* Ignore failures for kernel mapped binaries. */
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__mprotect (start, len, prot);
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else
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map->l_mach.bti_fail = __mmap (start, len, prot,
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MAP_FIXED|MAP_COPY|MAP_FILE,
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fd, off) == MAP_FAILED;
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}
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}
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static void
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bti_failed (struct link_map *l, const char *program)
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{
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if (program)
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_dl_fatal_printf ("%s: %s: failed to turn on BTI protection\n",
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program, l->l_name);
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else
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/* Note: the errno value is not available any more. */
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_dl_signal_error (0, l->l_name, "dlopen",
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N_("failed to turn on BTI protection"));
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}
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/* Enable BTI for L and its dependencies. */
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void
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_dl_bti_check (struct link_map *l, const char *program)
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{
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if (!GLRO(dl_aarch64_cpu_features).bti)
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return;
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if (l->l_mach.bti_fail)
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bti_failed (l, program);
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unsigned int i = l->l_searchlist.r_nlist;
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while (i-- > 0)
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{
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struct link_map *dep = l->l_initfini[i];
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if (dep->l_mach.bti_fail)
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bti_failed (dep, program);
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}
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}
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