about summary refs log tree commit diff
path: root/elf/dl-audit.c
blob: 00e794aa2689b87cd4bc78666a5cd9677b1bffa3 (plain) (blame)
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
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
/* Audit common functions.
   Copyright (C) 2021-2023 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
   <https://www.gnu.org/licenses/>.  */

#include <assert.h>
#include <link.h>
#include <ldsodefs.h>
#include <dl-machine.h>
#include <dl-runtime.h>
#include <dl-fixup-attribute.h>
#include <sys/param.h>

void
_dl_audit_activity_map (struct link_map *l, int action)
{
  struct audit_ifaces *afct = GLRO(dl_audit);
  for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
    {
      if (afct->activity != NULL)
	afct->activity (&link_map_audit_state (l, cnt)->cookie, action);
      afct = afct->next;
    }
}

void
_dl_audit_activity_nsid (Lmid_t nsid, int action)
{
  /* If head is NULL, the namespace has become empty, and the audit interface
     does not give us a way to signal LA_ACT_CONSISTENT for it because the
     first loaded module is used to identify the namespace.  */
  struct link_map *head = GL(dl_ns)[nsid]._ns_loaded;
  if (__glibc_likely (GLRO(dl_naudit) == 0)
      || head == NULL || head->l_auditing)
    return;

  _dl_audit_activity_map (head, action);
}

const char *
_dl_audit_objsearch (const char *name, struct link_map *l, unsigned int code)
{
  if (l == NULL || l->l_auditing || code == 0)
    return name;

  struct audit_ifaces *afct = GLRO(dl_audit);
  for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
    {
      if (afct->objsearch != NULL)
	{
	  struct auditstate *state = link_map_audit_state (l, cnt);
	  name = afct->objsearch (name, &state->cookie, code);
	  if (name == NULL)
	    return NULL;
	}
      afct = afct->next;
   }

  return name;
}

void
_dl_audit_objopen (struct link_map *l, Lmid_t nsid)
{
  if (__glibc_likely (GLRO(dl_naudit) == 0))
    return;

  struct audit_ifaces *afct = GLRO(dl_audit);
  for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
    {
      if (afct->objopen != NULL)
	{
	  struct auditstate *state = link_map_audit_state (l, cnt);
	  state->bindflags = afct->objopen (l, nsid, &state->cookie);
	  l->l_audit_any_plt |= state->bindflags != 0;
	}

      afct = afct->next;
   }
}

void
_dl_audit_objclose (struct link_map *l)
{
  if (__glibc_likely (GLRO(dl_naudit) == 0)
      || GL(dl_ns)[l->l_ns]._ns_loaded->l_auditing)
    return;

  struct audit_ifaces *afct = GLRO(dl_audit);
  for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
    {
      if (afct->objclose != NULL)
	{
	  struct auditstate *state= link_map_audit_state (l, cnt);
	  /* Return value is ignored.  */
	  afct->objclose (&state->cookie);
	}

      afct = afct->next;
    }
}

void
_dl_audit_preinit (struct link_map *l)
{
  if (__glibc_likely (GLRO(dl_naudit) == 0))
    return;

  struct audit_ifaces *afct = GLRO(dl_audit);
  for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
    {
      if (afct->preinit != NULL)
	afct->preinit (&link_map_audit_state (l, cnt)->cookie);
      afct = afct->next;
    }
}

void
_dl_audit_symbind_alt (struct link_map *l, const ElfW(Sym) *ref, void **value,
		       lookup_t result)
{
  if ((l->l_audit_any_plt | result->l_audit_any_plt) == 0)
    return;

  const char *strtab = (const char *) D_PTR (result, l_info[DT_STRTAB]);
  /* Compute index of the symbol entry in the symbol table of the DSO with
     the definition.  */
  unsigned int ndx = (ref - (ElfW(Sym) *) D_PTR (result, l_info[DT_SYMTAB]));

  unsigned int altvalue = 0;
  /* Synthesize a symbol record where the st_value field is the result.  */
  ElfW(Sym) sym = *ref;
  sym.st_value = (ElfW(Addr)) *value;

  struct audit_ifaces *afct = GLRO(dl_audit);
  for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
    {
      struct auditstate *match_audit = link_map_audit_state (l, cnt);
      struct auditstate *result_audit = link_map_audit_state (result, cnt);
      if (afct->symbind != NULL
	  && ((match_audit->bindflags & LA_FLG_BINDFROM) != 0
	      || ((result_audit->bindflags & LA_FLG_BINDTO)
		  != 0)))
	{
	  unsigned int flags = altvalue | LA_SYMB_DLSYM;
	  uintptr_t new_value = afct->symbind (&sym, ndx,
					       &match_audit->cookie,
					       &result_audit->cookie,
					       &flags, strtab + ref->st_name);
	  if (new_value != (uintptr_t) sym.st_value)
	    {
	      altvalue = LA_SYMB_ALTVALUE;
	      sym.st_value = new_value;
	    }

	  afct = afct->next;
	}

      *value = (void *) sym.st_value;
    }
}
rtld_hidden_def (_dl_audit_symbind_alt)

void
_dl_audit_symbind (struct link_map *l, struct reloc_result *reloc_result,
		   const ElfW(Sym) *defsym, DL_FIXUP_VALUE_TYPE *value,
		   lookup_t result)
{
  bool for_jmp_slot = reloc_result == NULL;

  /* Compute index of the symbol entry in the symbol table of the DSO
     with the definition.  */
  unsigned int boundndx = defsym - (ElfW(Sym) *) D_PTR (result,
							l_info[DT_SYMTAB]);
  if (!for_jmp_slot)
    {
      reloc_result->bound = result;
      reloc_result->boundndx = boundndx;
    }

  if ((l->l_audit_any_plt | result->l_audit_any_plt) == 0)
    {
      /* Set all bits since this symbol binding is not interesting.  */
      if (!for_jmp_slot)
	reloc_result->enterexit = (1u << DL_NNS) - 1;
      return;
    }

  /* Synthesize a symbol record where the st_value field is the result.  */
  ElfW(Sym) sym = *defsym;
  sym.st_value = DL_FIXUP_VALUE_ADDR (*value);

  /* Keep track whether there is any interest in tracing the call in the lower
     two bits.  */
  assert (DL_NNS * 2 <= sizeof (reloc_result->flags) * 8);
  assert ((LA_SYMB_NOPLTENTER | LA_SYMB_NOPLTEXIT) == 3);
  uint32_t enterexit = LA_SYMB_NOPLTENTER | LA_SYMB_NOPLTEXIT;

  const char *strtab2 = (const void *) D_PTR (result, l_info[DT_STRTAB]);

  unsigned int flags = 0;
  struct audit_ifaces *afct = GLRO(dl_audit);
  uintptr_t new_value = (uintptr_t) sym.st_value;
  for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
    {
      /* XXX Check whether both DSOs must request action or only one */
      struct auditstate *l_state = link_map_audit_state (l, cnt);
      struct auditstate *result_state = link_map_audit_state (result, cnt);
      if ((l_state->bindflags & LA_FLG_BINDFROM) != 0
	  && (result_state->bindflags & LA_FLG_BINDTO) != 0)
	{
	  if (afct->symbind != NULL)
	    {
	      flags |= for_jmp_slot ? LA_SYMB_NOPLTENTER | LA_SYMB_NOPLTEXIT
				    : 0;
	      new_value = afct->symbind (&sym, boundndx,
					 &l_state->cookie,
					 &result_state->cookie, &flags,
					 strtab2 + defsym->st_name);
	      if (new_value != (uintptr_t) sym.st_value)
		{
		  flags |= LA_SYMB_ALTVALUE;
		  sym.st_value = for_jmp_slot
		    ? DL_FIXUP_BINDNOW_ADDR_VALUE (new_value) : new_value;
		}
	    }

	  /* Remember the results for every audit library and store a summary
	     in the first two bits.  */
	  enterexit &= flags & (LA_SYMB_NOPLTENTER | LA_SYMB_NOPLTEXIT);
	  enterexit |= ((flags & (LA_SYMB_NOPLTENTER | LA_SYMB_NOPLTEXIT))
			<< ((cnt + 1) * 2));
	}
      else
	/* If the bind flags say this auditor is not interested, set the bits
	   manually.  */
	enterexit |= ((LA_SYMB_NOPLTENTER | LA_SYMB_NOPLTEXIT)
		      << ((cnt + 1) * 2));
      afct = afct->next;
    }

  if (!for_jmp_slot)
    {
      reloc_result->enterexit = enterexit;
      reloc_result->flags = flags;
    }

  if (flags & LA_SYMB_ALTVALUE)
    DL_FIXUP_BINDNOW_RELOC (value, new_value, sym.st_value);
}

void
_dl_audit_pltenter (struct link_map *l, struct reloc_result *reloc_result,
		    DL_FIXUP_VALUE_TYPE *value, void *regs, long int *framesize)
{
  /* Don't do anything if no auditor wants to intercept this call.  */
  if (GLRO(dl_naudit) == 0
      || (reloc_result->enterexit & LA_SYMB_NOPLTENTER))
    return;

  /* Sanity check:  DL_FIXUP_VALUE_CODE_ADDR (value) should have been
     initialized earlier in this function or in another thread.  */
  assert (DL_FIXUP_VALUE_CODE_ADDR (*value) != 0);
  ElfW(Sym) *defsym = ((ElfW(Sym) *) D_PTR (reloc_result->bound,
					    l_info[DT_SYMTAB])
		       + reloc_result->boundndx);

  /* Set up the sym parameter.  */
  ElfW(Sym) sym = *defsym;
  sym.st_value = DL_FIXUP_VALUE_ADDR (*value);

  /* Get the symbol name.  */
  const char *strtab = (const void *) D_PTR (reloc_result->bound,
					     l_info[DT_STRTAB]);
  const char *symname = strtab + sym.st_name;

  /* Keep track of overwritten addresses.  */
  unsigned int flags = reloc_result->flags;

  struct audit_ifaces *afct = GLRO(dl_audit);
  for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
    {
      if (afct->ARCH_LA_PLTENTER != NULL
	  && (reloc_result->enterexit
	      & (LA_SYMB_NOPLTENTER << (2 * (cnt + 1)))) == 0)
	{
	  long int new_framesize = -1;
	  struct auditstate *l_state = link_map_audit_state (l, cnt);
	  struct auditstate *bound_state
	    = link_map_audit_state (reloc_result->bound, cnt);
	  uintptr_t new_value
	    = afct->ARCH_LA_PLTENTER (&sym, reloc_result->boundndx,
				      &l_state->cookie, &bound_state->cookie,
				      regs, &flags, symname, &new_framesize);
	  if (new_value != (uintptr_t) sym.st_value)
	    {
	      flags |= LA_SYMB_ALTVALUE;
	      sym.st_value = new_value;
	    }

	  /* Remember the results for every audit library and store a summary
	     in the first two bits.  */
	  reloc_result->enterexit |= ((flags & (LA_SYMB_NOPLTENTER
						| LA_SYMB_NOPLTEXIT))
				      << (2 * (cnt + 1)));

	  if ((reloc_result->enterexit & (LA_SYMB_NOPLTEXIT
					  << (2 * (cnt + 1))))
	      == 0 && new_framesize != -1 && *framesize != -2)
	    {
	      /* If this is the first call providing information, use it.  */
	      if (*framesize == -1)
		*framesize = new_framesize;
	      /* If two pltenter calls provide conflicting information, use
		 the larger value.  */
	      else if (new_framesize != *framesize)
		*framesize = MAX (new_framesize, *framesize);
	    }
	}

      afct = afct->next;
    }

  *value = DL_FIXUP_ADDR_VALUE (sym.st_value);
}

void
DL_ARCH_FIXUP_ATTRIBUTE
_dl_audit_pltexit (struct link_map *l, ElfW(Word) reloc_arg,
		   const void *inregs, void *outregs)
{
  const uintptr_t pltgot = (uintptr_t) D_PTR (l, l_info[DT_PLTGOT]);

  /* This is the address in the array where we store the result of previous
     relocations.  */
  // XXX Maybe the bound information must be stored on the stack since
  // XXX with bind_not a new value could have been stored in the meantime.
  struct reloc_result *reloc_result =
    &l->l_reloc_result[reloc_index (pltgot, reloc_arg, sizeof (PLTREL))];
  ElfW(Sym) *defsym = ((ElfW(Sym) *) D_PTR (reloc_result->bound,
					    l_info[DT_SYMTAB])
		       + reloc_result->boundndx);

  /* Set up the sym parameter.  */
  ElfW(Sym) sym = *defsym;
  sym.st_value = DL_FIXUP_VALUE_ADDR (reloc_result->addr);

  /* Get the symbol name.  */
  const char *strtab = (const void *) D_PTR (reloc_result->bound,
					     l_info[DT_STRTAB]);
  const char *symname = strtab + sym.st_name;

  struct audit_ifaces *afct = GLRO(dl_audit);
  for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
    {
      if (afct->ARCH_LA_PLTEXIT != NULL
	  && (reloc_result->enterexit
	      & (LA_SYMB_NOPLTEXIT >> (2 * cnt))) == 0)
	{
	  struct auditstate *l_state = link_map_audit_state (l, cnt);
	  struct auditstate *bound_state
	    = link_map_audit_state (reloc_result->bound, cnt);
	  afct->ARCH_LA_PLTEXIT (&sym, reloc_result->boundndx,
				 &l_state->cookie, &bound_state->cookie,
				 inregs, outregs, symname);
	}

      afct = afct->next;
    }
}