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d1b9bee29a
The vDSO is is listed in the link_map chain, but is never the subject of
an la_objopen call. A new internal flag __RTLD_VDSO is added that
acts as __RTLD_OPENEXEC to allocate the required 'struct auditstate'
extra space for the 'struct link_map'.
The return value from the callback is currently ignored, since there
is no PLT call involved by glibc when using the vDSO, neither the vDSO
are exported directly.
Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
(cherry picked from commit f0e23d34a7)
Resolved conflicts:
elf/Makefile
114 lines
4.0 KiB
C
114 lines
4.0 KiB
C
/* Set up the data structures for the system-supplied DSO.
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Copyright (C) 2012-2021 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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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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static inline void __attribute__ ((always_inline))
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setup_vdso (struct link_map *main_map __attribute__ ((unused)),
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struct link_map ***first_preload __attribute__ ((unused)))
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{
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#ifdef NEED_DL_SYSINFO_DSO
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if (GLRO(dl_sysinfo_dso) == NULL)
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return;
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/* Do an abridged version of the work _dl_map_object_from_fd would do
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to map in the object. It's already mapped and prelinked (and
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better be, since it's read-only and so we couldn't relocate it).
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We just want our data structures to describe it as if we had just
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mapped and relocated it normally. */
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struct link_map *l = _dl_new_object ((char *) "", "", lt_library, NULL,
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__RTLD_VDSO, LM_ID_BASE);
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if (__glibc_likely (l != NULL))
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{
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l->l_phdr = ((const void *) GLRO(dl_sysinfo_dso)
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+ GLRO(dl_sysinfo_dso)->e_phoff);
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l->l_phnum = GLRO(dl_sysinfo_dso)->e_phnum;
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for (uint_fast16_t i = 0; i < l->l_phnum; ++i)
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{
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const ElfW(Phdr) *const ph = &l->l_phdr[i];
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if (ph->p_type == PT_DYNAMIC)
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{
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l->l_ld = (void *) ph->p_vaddr;
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l->l_ldnum = ph->p_memsz / sizeof (ElfW(Dyn));
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l->l_ld_readonly = (ph->p_flags & PF_W) == 0;
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}
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else if (ph->p_type == PT_LOAD)
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{
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if (! l->l_addr)
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l->l_addr = ph->p_vaddr;
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if (ph->p_vaddr + ph->p_memsz >= l->l_map_end)
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l->l_map_end = ph->p_vaddr + ph->p_memsz;
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if ((ph->p_flags & PF_X)
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&& ph->p_vaddr + ph->p_memsz >= l->l_text_end)
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l->l_text_end = ph->p_vaddr + ph->p_memsz;
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}
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else
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/* There must be no TLS segment. */
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assert (ph->p_type != PT_TLS);
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}
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l->l_map_start = (ElfW(Addr)) GLRO(dl_sysinfo_dso);
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l->l_addr = l->l_map_start - l->l_addr;
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l->l_map_end += l->l_addr;
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l->l_text_end += l->l_addr;
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l->l_ld = (void *) ((ElfW(Addr)) l->l_ld + l->l_addr);
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elf_get_dynamic_info (l, false, false);
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_dl_setup_hash (l);
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l->l_relocated = 1;
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/* The vDSO is always used. */
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l->l_used = 1;
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/* Initialize l_local_scope to contain just this map. This allows
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the use of dl_lookup_symbol_x to resolve symbols within the vdso.
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So we create a single entry list pointing to l_real as its only
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element */
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l->l_local_scope[0]->r_nlist = 1;
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l->l_local_scope[0]->r_list = &l->l_real;
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/* Now that we have the info handy, use the DSO image's soname
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so this object can be looked up by name. */
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if (l->l_info[DT_SONAME] != NULL)
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{
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char *dsoname = ((char *) D_PTR (l, l_info[DT_STRTAB])
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+ l->l_info[DT_SONAME]->d_un.d_val);
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l->l_libname->name = dsoname;
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l->l_name = dsoname;
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}
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/* Add the vDSO to the object list. */
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_dl_add_to_namespace_list (l, LM_ID_BASE);
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# if IS_IN (rtld)
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/* Rearrange the list so this DSO appears after rtld_map. */
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assert (l->l_next == NULL);
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assert (l->l_prev == main_map);
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GL(dl_rtld_map).l_next = l;
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l->l_prev = &GL(dl_rtld_map);
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*first_preload = &l->l_next;
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# else
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GL(dl_nns) = 1;
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# endif
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/* We have a prelinked DSO preloaded by the system. */
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GLRO(dl_sysinfo_map) = l;
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# ifdef NEED_DL_SYSINFO
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if (GLRO(dl_sysinfo) == DL_SYSINFO_DEFAULT)
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GLRO(dl_sysinfo) = GLRO(dl_sysinfo_dso)->e_entry + l->l_addr;
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# endif
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}
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#endif
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}
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