summaryrefslogtreecommitdiff
path: root/sysdeps/x86/dl-prop.h
blob: 35d3f16a232def669fbba96c04d52328cc81d644 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
/* Support for GNU properties.  x86 version.
   Copyright (C) 2018 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.  */

#ifndef _DL_PROP_H
#define _DL_PROP_H

#include <not-cancel.h>

extern void _dl_cet_check (struct link_map *, const char *)
    attribute_hidden;
extern void _dl_cet_open_check (struct link_map *)
    attribute_hidden;

static inline void __attribute__ ((always_inline))
_rtld_main_check (struct link_map *m, const char *program)
{
#if CET_ENABLED
  _dl_cet_check (m, program);
#endif
}

static inline void __attribute__ ((always_inline))
_dl_open_check (struct link_map *m)
{
#if CET_ENABLED
  _dl_cet_open_check (m);
#endif
}

static inline void __attribute__ ((unused))
_dl_process_cet_property_note (struct link_map *l,
			      const ElfW(Nhdr) *note,
			      const ElfW(Addr) size,
			      const ElfW(Addr) align)
{
#if CET_ENABLED
  /* The NT_GNU_PROPERTY_TYPE_0 note must be aliged to 4 bytes in
     32-bit objects and to 8 bytes in 64-bit objects.  Skip notes
     with incorrect alignment.  */
  if (align != (__ELF_NATIVE_CLASS / 8))
    return;

  const ElfW(Addr) start = (ElfW(Addr)) note;

  while ((ElfW(Addr)) (note + 1) - start < size)
    {
      /* Find the NT_GNU_PROPERTY_TYPE_0 note.  */
      if (note->n_namesz == 4
	  && note->n_type == NT_GNU_PROPERTY_TYPE_0
	  && memcmp (note + 1, "GNU", 4) == 0)
	{
	  /* Check for invalid property.  */
	  if (note->n_descsz < 8
	      || (note->n_descsz % sizeof (ElfW(Addr))) != 0)
	    break;

	  /* Start and end of property array.  */
	  unsigned char *ptr = (unsigned char *) (note + 1) + 4;
	  unsigned char *ptr_end = ptr + note->n_descsz;

	  while (ptr < ptr_end)
	    {
	      unsigned int type = *(unsigned int *) ptr;
	      unsigned int datasz = *(unsigned int *) (ptr + 4);

	      ptr += 8;
	      if ((ptr + datasz) > ptr_end)
		break;

	      if (type == GNU_PROPERTY_X86_FEATURE_1_AND
		  && datasz == 4)
		{
		  unsigned int feature_1 = *(unsigned int *) ptr;
		  if ((feature_1 & GNU_PROPERTY_X86_FEATURE_1_IBT))
		    l->l_cet |= lc_ibt;
		  if ((feature_1 & GNU_PROPERTY_X86_FEATURE_1_SHSTK))
		    l->l_cet |= lc_shstk;
		  break;
		}
	    }
	}

      /* NB: Note sections like .note.ABI-tag and .note.gnu.build-id are
	 aligned to 4 bytes in 64-bit ELF objects.  */
      note = ((const void *) note
	      + ELF_NOTE_NEXT_OFFSET (note->n_namesz, note->n_descsz,
				      align));
    }
#endif
}

#ifdef FILEBUF_SIZE
static inline int __attribute__ ((unused))
_dl_process_pt_note (struct link_map *l, const ElfW(Phdr) *ph,
		     int fd, struct filebuf *fbp)
{
# if CET_ENABLED
  const ElfW(Nhdr) *note;
  ElfW(Nhdr) *note_malloced = NULL;
  ElfW(Addr) size = ph->p_filesz;

  if (ph->p_offset + size <= (size_t) fbp->len)
    note = (const void *) (fbp->buf + ph->p_offset);
  else
    {
      if (size < __MAX_ALLOCA_CUTOFF)
	note = alloca (size);
      else
	{
	  note_malloced = malloc (size);
	  note = note_malloced;
	}
      __lseek (fd, ph->p_offset, SEEK_SET);
      if (__read_nocancel (fd, (void *) note, size) != size)
	{
	  if (note_malloced)
	    free (note_malloced);
	  return -1;
	}
    }

  _dl_process_cet_property_note (l, note, size, ph->p_align);
  if (note_malloced)
    free (note_malloced);
# endif
  return 0;
}
#endif

static inline int __attribute__ ((unused))
_rtld_process_pt_note (struct link_map *l, const ElfW(Phdr) *ph)
{
  const ElfW(Nhdr) *note = (const void *) (ph->p_vaddr + l->l_addr);
  _dl_process_cet_property_note (l, note, ph->p_memsz, ph->p_align);
  return 0;
}

#endif /* _DL_PROP_H */