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7374c02b68
Refine commit 349b0441da:
1. Copy relocations for extern protected data do not work properly,
regardless whether GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS is used.
It makes sense to produce a warning unconditionally.
2. Non-zero value of an undefined function symbol may break pointer
equality, but may be benign in many cases (many programs don't take the
address in the shared object then compare it with the address in the
executable). Reword the diagnostic to be clearer.
3. Remove the unneeded condition !(undef_map->l_1_needed &
GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS). If the executable does
not not have GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS (can only
occur in error cases), the diagnostic should be emitted as well.
When the defining shared object has
GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS, report an error to apply
the intended enforcement.
59 lines
2.2 KiB
C
59 lines
2.2 KiB
C
/* Support for STV_PROTECTED visibility. Generic version.
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Copyright (C) 2021-2022 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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#ifndef _DL_PROTECTED_H
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#define _DL_PROTECTED_H
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static inline void __attribute__ ((always_inline))
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_dl_check_protected_symbol (const char *undef_name,
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const struct link_map *undef_map,
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const ElfW(Sym) *ref,
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const struct link_map *map,
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int type_class)
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{
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if (undef_map == NULL || undef_map->l_type != lt_executable)
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return;
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if (type_class & ELF_RTYPE_CLASS_COPY)
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/* Disallow copy relocations in executable against protected
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data symbols in a shared object which needs indirect external
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access. */
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_dl_error_printf ("warning: copy relocation against non-copyable "
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"protected symbol `%s' in `%s'\n",
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undef_name, map->l_name);
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else if ((type_class & ELF_RTYPE_CLASS_PLT) && ref->st_value != 0
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&& ref->st_shndx == SHN_UNDEF)
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/* Disallow non-zero symbol values of undefined symbols in
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executable, which are used as the function pointer, against
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protected function symbols in a shared object with indirect
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external access. */
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_dl_error_printf (
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"warning: direct reference to "
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"protected function `%s' in `%s' may break pointer equality\n",
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undef_name, map->l_name);
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else
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return;
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if (map->l_1_needed & GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS)
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_dl_signal_error (
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0, map->l_name, undef_name,
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N_ ("error due to GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS"));
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}
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#endif /* _DL_PROTECTED_H */
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