1/*
2 * Copyright (C) 2015 The Android Open Source Project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *  * Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 *  * Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in
12 *    the documentation and/or other materials provided with the
13 *    distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29#include "linker.h"
30#include "linker_debug.h"
31#include "linker_relocs.h"
32#include "linker_reloc_iterators.h"
33#include "linker_sleb128.h"
34
35template bool soinfo::relocate<plain_reloc_iterator>(const VersionTracker& version_tracker,
36                                                     plain_reloc_iterator&& rel_iterator,
37                                                     const soinfo_list_t& global_group,
38                                                     const soinfo_list_t& local_group);
39
40template bool soinfo::relocate<packed_reloc_iterator<sleb128_decoder>>(
41    const VersionTracker& version_tracker,
42    packed_reloc_iterator<sleb128_decoder>&& rel_iterator,
43    const soinfo_list_t& global_group,
44    const soinfo_list_t& local_group);
45
46template <typename ElfRelIteratorT>
47bool soinfo::relocate(const VersionTracker& version_tracker,
48                      ElfRelIteratorT&& rel_iterator,
49                      const soinfo_list_t& global_group,
50                      const soinfo_list_t& local_group) {
51  for (size_t idx = 0; rel_iterator.has_next(); ++idx) {
52    const auto rel = rel_iterator.next();
53
54    if (rel == nullptr) {
55      return false;
56    }
57
58    ElfW(Word) type = ELFW(R_TYPE)(rel->r_info);
59    ElfW(Word) sym = ELFW(R_SYM)(rel->r_info);
60
61    ElfW(Addr) reloc = static_cast<ElfW(Addr)>(rel->r_offset + load_bias);
62    ElfW(Addr) sym_addr = 0;
63    const char* sym_name = nullptr;
64
65    DEBUG("Processing '%s' relocation at index %zd", get_soname(), idx);
66    if (type == R_GENERIC_NONE) {
67      continue;
68    }
69
70    const ElfW(Sym)* s = nullptr;
71    soinfo* lsi = nullptr;
72
73    if (sym != 0) {
74      sym_name = get_string(symtab_[sym].st_name);
75      const version_info* vi = nullptr;
76
77      if (!lookup_version_info(version_tracker, sym, sym_name, &vi)) {
78        return false;
79      }
80
81      if (!soinfo_do_lookup(this, sym_name, vi, &lsi, global_group, local_group, &s)) {
82        return false;
83      }
84
85      if (s == nullptr) {
86        // mips does not support relocation with weak-undefined symbols
87        DL_ERR("cannot locate symbol \"%s\" referenced by \"%s\"...", sym_name, get_soname());
88        return false;
89      } else {
90        // We got a definition.
91        sym_addr = lsi->resolve_symbol_address(s);
92      }
93      count_relocation(kRelocSymbol);
94    }
95
96    switch (type) {
97      case R_MIPS_REL32:
98#if defined(__LP64__)
99        // MIPS Elf64_Rel entries contain compound relocations
100        // We only handle the R_MIPS_NONE|R_MIPS_64|R_MIPS_REL32 case
101        if (ELF64_R_TYPE2(rel->r_info) != R_MIPS_64 ||
102            ELF64_R_TYPE3(rel->r_info) != R_MIPS_NONE) {
103          DL_ERR("Unexpected compound relocation type:%d type2:%d type3:%d @ %p (%zu)",
104                 type, static_cast<unsigned>(ELF64_R_TYPE2(rel->r_info)),
105                 static_cast<unsigned>(ELF64_R_TYPE3(rel->r_info)), rel, idx);
106          return false;
107        }
108#endif
109        count_relocation(s == nullptr ? kRelocAbsolute : kRelocRelative);
110        MARK(rel->r_offset);
111        TRACE_TYPE(RELO, "RELO REL32 %08zx <- %08zx %s", static_cast<size_t>(reloc),
112                   static_cast<size_t>(sym_addr), sym_name ? sym_name : "*SECTIONHDR*");
113        if (s != nullptr) {
114          *reinterpret_cast<ElfW(Addr)*>(reloc) += sym_addr;
115        } else {
116          *reinterpret_cast<ElfW(Addr)*>(reloc) += load_bias;
117        }
118        break;
119      default:
120        DL_ERR("unknown reloc type %d @ %p (%zu)", type, rel, idx);
121        return false;
122    }
123  }
124  return true;
125}
126
127bool soinfo::mips_relocate_got(const VersionTracker& version_tracker,
128                               const soinfo_list_t& global_group,
129                               const soinfo_list_t& local_group) {
130  ElfW(Addr)** got = plt_got_;
131  if (got == nullptr) {
132    return true;
133  }
134
135  // got[0] is the address of the lazy resolver function.
136  // got[1] may be used for a GNU extension.
137  // Set it to a recognizable address in case someone calls it (should be _rtld_bind_start).
138  // FIXME: maybe this should be in a separate routine?
139  if ((flags_ & FLAG_LINKER) == 0) {
140    size_t g = 0;
141    got[g++] = reinterpret_cast<ElfW(Addr)*>(0xdeadbeef);
142    if (reinterpret_cast<intptr_t>(got[g]) < 0) {
143      got[g++] = reinterpret_cast<ElfW(Addr)*>(0xdeadfeed);
144    }
145    // Relocate the local GOT entries.
146    for (; g < mips_local_gotno_; g++) {
147      got[g] = reinterpret_cast<ElfW(Addr)*>(reinterpret_cast<uintptr_t>(got[g]) + load_bias);
148    }
149  }
150
151  // Now for the global GOT entries...
152  got = plt_got_ + mips_local_gotno_;
153  for (ElfW(Word) sym = mips_gotsym_; sym < mips_symtabno_; sym++, got++) {
154    // This is an undefined reference... try to locate it.
155    const ElfW(Sym)* local_sym = symtab_ + sym;
156    const char* sym_name = get_string(local_sym->st_name);
157    soinfo* lsi = nullptr;
158    const ElfW(Sym)* s = nullptr;
159
160    ElfW(Word) st_visibility = (local_sym->st_other & 0x3);
161
162    if (st_visibility == STV_DEFAULT) {
163      const version_info* vi = nullptr;
164
165      if (!lookup_version_info(version_tracker, sym, sym_name, &vi)) {
166        return false;
167      }
168
169      if (!soinfo_do_lookup(this, sym_name, vi, &lsi, global_group, local_group, &s)) {
170        return false;
171      }
172    } else if (st_visibility == STV_PROTECTED) {
173      if (local_sym->st_value == 0) {
174        DL_ERR("%s: invalid symbol \"%s\" (PROTECTED/UNDEFINED) ", get_soname(), sym_name);
175        return false;
176      }
177      s = local_sym;
178      lsi = this;
179    } else {
180      DL_ERR("%s: invalid symbol \"%s\" visibility: 0x%x", get_soname(), sym_name, st_visibility);
181      return false;
182    }
183
184    if (s == nullptr) {
185      // We only allow an undefined symbol if this is a weak reference.
186      if (ELF_ST_BIND(local_sym->st_info) != STB_WEAK) {
187        DL_ERR("%s: cannot locate \"%s\"...", get_soname(), sym_name);
188        return false;
189      }
190      *got = 0;
191    } else {
192      // FIXME: is this sufficient?
193      // For reference see NetBSD link loader
194      // http://cvsweb.netbsd.org/bsdweb.cgi/src/libexec/ld.elf_so/arch/mips/mips_reloc.c?rev=1.53&content-type=text/x-cvsweb-markup
195      *got = reinterpret_cast<ElfW(Addr)*>(lsi->resolve_symbol_address(s));
196    }
197  }
198  return true;
199}
200
201