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/* Support for GNU properties. x86 version.
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Copyright (C) 2018 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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<http://www.gnu.org/licenses/>. */
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#ifndef _DL_PROP_H
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#define _DL_PROP_H
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#include <not-cancel.h>
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extern void _dl_cet_check (struct link_map *, const char *)
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attribute_hidden;
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extern void _dl_cet_open_check (struct link_map *)
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attribute_hidden;
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static inline void __attribute__ ((always_inline))
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_rtld_main_check (struct link_map *m, const char *program)
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{
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#if CET_ENABLED
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_dl_cet_check (m, program);
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#endif
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}
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static inline void __attribute__ ((always_inline))
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_dl_open_check (struct link_map *m)
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{
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#if CET_ENABLED
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_dl_cet_open_check (m);
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#endif
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}
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static inline void __attribute__ ((unused))
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_dl_process_cet_property_note (struct link_map *l,
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const ElfW(Nhdr) *note,
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const ElfW(Addr) size,
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const ElfW(Addr) align)
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{
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#if CET_ENABLED
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/* Skip if we have seen a NT_GNU_PROPERTY_TYPE_0 note before. */
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if (l->l_cet != lc_unknown)
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return;
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/* The NT_GNU_PROPERTY_TYPE_0 note must be aliged to 4 bytes in
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32-bit objects and to 8 bytes in 64-bit objects. Skip notes
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with incorrect alignment. */
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if (align != (__ELF_NATIVE_CLASS / 8))
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return;
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const ElfW(Addr) start = (ElfW(Addr)) note;
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unsigned int feature_1 = 0;
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unsigned int last_type = 0;
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while ((ElfW(Addr)) (note + 1) - start < size)
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{
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/* Find the NT_GNU_PROPERTY_TYPE_0 note. */
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if (note->n_namesz == 4
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&& note->n_type == NT_GNU_PROPERTY_TYPE_0
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&& memcmp (note + 1, "GNU", 4) == 0)
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{
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/* Stop if we see more than one GNU property note which may
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be generated by the older linker. */
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if (l->l_cet != lc_unknown)
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return;
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/* Check CET status now. */
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l->l_cet = lc_none;
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/* Check for invalid property. */
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if (note->n_descsz < 8
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|| (note->n_descsz % sizeof (ElfW(Addr))) != 0)
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return;
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/* Start and end of property array. */
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unsigned char *ptr = (unsigned char *) (note + 1) + 4;
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unsigned char *ptr_end = ptr + note->n_descsz;
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do
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{
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unsigned int type = *(unsigned int *) ptr;
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unsigned int datasz = *(unsigned int *) (ptr + 4);
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/* Property type must be in ascending order. */
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if (type < last_type)
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return;
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ptr += 8;
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if ((ptr + datasz) > ptr_end)
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return;
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last_type = type;
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if (type == GNU_PROPERTY_X86_FEATURE_1_AND)
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{
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/* The size of GNU_PROPERTY_X86_FEATURE_1_AND is 4
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bytes. When seeing GNU_PROPERTY_X86_FEATURE_1_AND,
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we stop the search regardless if its size is correct
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or not. There is no point to continue if this note
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is ill-formed. */
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if (datasz != 4)
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return;
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feature_1 = *(unsigned int *) ptr;
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/* Keep searching for the next GNU property note
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generated by the older linker. */
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break;
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}
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else if (type > GNU_PROPERTY_X86_FEATURE_1_AND)
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{
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/* Stop since property type is in ascending order. */
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return;
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}
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/* Check the next property item. */
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ptr += ALIGN_UP (datasz, sizeof (ElfW(Addr)));
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}
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while ((ptr_end - ptr) >= 8);
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}
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/* NB: Note sections like .note.ABI-tag and .note.gnu.build-id are
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aligned to 4 bytes in 64-bit ELF objects. */
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note = ((const void *) note
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+ ELF_NOTE_NEXT_OFFSET (note->n_namesz, note->n_descsz,
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align));
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}
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/* We get here only if there is one or no GNU property note. */
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if ((feature_1 & GNU_PROPERTY_X86_FEATURE_1_IBT))
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l->l_cet |= lc_ibt;
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if ((feature_1 & GNU_PROPERTY_X86_FEATURE_1_SHSTK))
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l->l_cet |= lc_shstk;
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#endif
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}
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#ifdef FILEBUF_SIZE
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static inline int __attribute__ ((unused))
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_dl_process_pt_note (struct link_map *l, const ElfW(Phdr) *ph,
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int fd, struct filebuf *fbp)
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{
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# if CET_ENABLED
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const ElfW(Nhdr) *note;
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ElfW(Nhdr) *note_malloced = NULL;
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ElfW(Addr) size = ph->p_filesz;
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if (ph->p_offset + size <= (size_t) fbp->len)
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note = (const void *) (fbp->buf + ph->p_offset);
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else
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{
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if (size < __MAX_ALLOCA_CUTOFF)
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note = alloca (size);
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else
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{
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note_malloced = malloc (size);
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note = note_malloced;
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}
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__lseek (fd, ph->p_offset, SEEK_SET);
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if (__read_nocancel (fd, (void *) note, size) != size)
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{
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if (note_malloced)
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free (note_malloced);
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return -1;
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}
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}
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_dl_process_cet_property_note (l, note, size, ph->p_align);
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if (note_malloced)
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free (note_malloced);
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# endif
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return 0;
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}
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#endif
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static inline int __attribute__ ((unused))
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_rtld_process_pt_note (struct link_map *l, const ElfW(Phdr) *ph)
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{
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const ElfW(Nhdr) *note = (const void *) (ph->p_vaddr + l->l_addr);
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_dl_process_cet_property_note (l, note, ph->p_memsz, ph->p_align);
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return 0;
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}
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#endif /* _DL_PROP_H */
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