1 /* $NetBSD: mdreloc.c,v 1.30 2014/08/25 20:40:53 joerg Exp $ */
2
3 #include <sys/cdefs.h>
4 #ifndef lint
5 __RCSID("$NetBSD: mdreloc.c,v 1.30 2014/08/25 20:40:53 joerg Exp $");
6 #endif /* not lint */
7
8 #include <sys/cdefs.h>
9 #ifndef lint
10 __RCSID("$NetBSD: mdreloc.c,v 1.30 2014/08/25 20:40:53 joerg Exp $");
11 #endif /* not lint */
12
13 #include <sys/types.h>
14
15 #include "debug.h"
16 #include "rtld.h"
17
18 void _rtld_bind_start(void);
19 void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr);
20 caddr_t _rtld_bind(const Obj_Entry *, Elf_Word);
21 static inline int _rtld_relocate_plt_object(const Obj_Entry *,
22 const Elf_Rela *, Elf_Addr *);
23
24 void
_rtld_setup_pltgot(const Obj_Entry * obj)25 _rtld_setup_pltgot(const Obj_Entry *obj)
26 {
27 obj->pltgot[1] = (Elf_Addr) obj;
28 obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start;
29 }
30
31 void
_rtld_relocate_nonplt_self(Elf_Dyn * dynp,Elf_Addr relocbase)32 _rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase)
33 {
34 const Elf_Rela *rela = 0, *relalim;
35 Elf_Addr relasz = 0;
36 Elf_Addr *where;
37
38 for (; dynp->d_tag != DT_NULL; dynp++) {
39 switch (dynp->d_tag) {
40 case DT_RELA:
41 rela = (const Elf_Rela *)(relocbase + dynp->d_un.d_ptr);
42 break;
43 case DT_RELASZ:
44 relasz = dynp->d_un.d_val;
45 break;
46 }
47 }
48 relalim = (const Elf_Rela *)((const uint8_t *)rela + relasz);
49 for (; rela < relalim; rela++) {
50 where = (Elf_Addr *)(relocbase + rela->r_offset);
51 *where = (Elf_Addr)(relocbase + rela->r_addend);
52 }
53 }
54
55 int
_rtld_relocate_nonplt_objects(Obj_Entry * obj)56 _rtld_relocate_nonplt_objects(Obj_Entry *obj)
57 {
58 const Elf_Rela *rela;
59
60 for (rela = obj->rela; rela < obj->relalim; rela++) {
61 Elf_Addr *where;
62 const Elf_Sym *def;
63 const Obj_Entry *defobj;
64 Elf_Addr tmp;
65 unsigned long symnum;
66
67 where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
68 symnum = ELF_R_SYM(rela->r_info);
69
70 switch (ELF_R_TYPE(rela->r_info)) {
71 case R_TYPE(NONE):
72 break;
73
74 case R_TYPE(32): /* word32 S + A */
75 case R_TYPE(GLOB_DAT): /* word32 S + A */
76 def = _rtld_find_symdef(symnum, obj, &defobj, false);
77 if (def == NULL)
78 return -1;
79
80 tmp = (Elf_Addr)(defobj->relocbase + def->st_value +
81 rela->r_addend);
82
83 if (*where != tmp)
84 *where = tmp;
85 rdbg(("32/GLOB_DAT %s in %s --> %p in %s",
86 obj->strtab + obj->symtab[symnum].st_name,
87 obj->path, (void *)*where, defobj->path));
88 break;
89
90 case R_TYPE(RELATIVE): /* word32 B + A */
91 tmp = (Elf_Addr)(obj->relocbase + rela->r_addend);
92 if (*where != tmp)
93 *where = tmp;
94 rdbg(("RELATIVE in %s --> %p", obj->path,
95 (void *)*where));
96 break;
97
98 case R_TYPE(COPY):
99 /*
100 * These are deferred until all other relocations have
101 * been done. All we do here is make sure that the
102 * COPY relocation is not in a shared library. They
103 * are allowed only in executable files.
104 */
105 if (obj->isdynamic) {
106 _rtld_error(
107 "%s: Unexpected R_COPY relocation in shared library",
108 obj->path);
109 return -1;
110 }
111 rdbg(("COPY (avoid in main)"));
112 break;
113
114 default:
115 rdbg(("sym = %lu, type = %lu, offset = %p, "
116 "addend = %p, contents = %p, symbol = %s",
117 symnum, (u_long)ELF_R_TYPE(rela->r_info),
118 (void *)rela->r_offset, (void *)rela->r_addend,
119 (void *)*where,
120 obj->strtab + obj->symtab[symnum].st_name));
121 _rtld_error("%s: Unsupported relocation type %ld "
122 "in non-PLT relocations",
123 obj->path, (u_long) ELF_R_TYPE(rela->r_info));
124 return -1;
125 }
126 }
127 return 0;
128 }
129
130 int
_rtld_relocate_plt_lazy(const Obj_Entry * obj)131 _rtld_relocate_plt_lazy(const Obj_Entry *obj)
132 {
133 const Elf_Rela *rela;
134
135 if (!obj->relocbase)
136 return 0;
137
138 for (rela = obj->pltrela; rela < obj->pltrelalim; rela++) {
139 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
140
141 assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JMP_SLOT));
142
143 /* Just relocate the GOT slots pointing into the PLT */
144 *where += (Elf_Addr)obj->relocbase;
145 rdbg(("lazy fixup pltgot %p in %s --> %p", where, obj->path,
146 (void *)*where));
147 }
148
149 return 0;
150 }
151
152 static inline int
_rtld_relocate_plt_object(const Obj_Entry * obj,const Elf_Rela * rela,Elf_Addr * tp)153 _rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rela *rela, Elf_Addr *tp)
154 {
155 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
156 Elf_Addr new_value;
157 const Elf_Sym *def;
158 const Obj_Entry *defobj;
159 unsigned long info = rela->r_info;
160
161 assert(ELF_R_TYPE(info) == R_TYPE(JMP_SLOT));
162
163 def = _rtld_find_plt_symdef(ELF_R_SYM(info), obj, &defobj, tp != NULL);
164 if (__predict_false(def == NULL))
165 return -1;
166 if (__predict_false(def == &_rtld_sym_zero))
167 return 0;
168
169 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) {
170 if (tp == NULL)
171 return 0;
172 new_value = _rtld_resolve_ifunc(defobj, def);
173 } else {
174 new_value = (Elf_Addr)(defobj->relocbase + def->st_value +
175 rela->r_addend);
176 }
177 rdbg(("bind now/fixup pltgot %p in %s --> old=%p new=%p", where,
178 defobj->strtab + def->st_name, (void *)*where, (void *)new_value));
179 if (*where != new_value)
180 *where = new_value;
181
182 if (tp)
183 *tp = new_value - rela->r_addend;
184
185 return 0;
186 }
187
188 caddr_t
_rtld_bind(const Obj_Entry * obj,Elf_Word reloff)189 _rtld_bind(const Obj_Entry *obj, Elf_Word reloff)
190 {
191 const Elf_Rela *rela = (const Elf_Rela *)((const uint8_t *)obj->pltrela + reloff);
192 Elf_Addr result;
193 int err;
194
195 result = 0; /* XXX gcc */
196
197 _rtld_shared_enter();
198 err = _rtld_relocate_plt_object(obj, rela, &result);
199 if (err)
200 _rtld_die();
201 _rtld_shared_exit();
202
203 return (caddr_t)result;
204 }
205
206 int
_rtld_relocate_plt_objects(const Obj_Entry * obj)207 _rtld_relocate_plt_objects(const Obj_Entry *obj)
208 {
209 const Elf_Rela *rela;
210
211 for (rela = obj->pltrela; rela < obj->pltrelalim; rela++)
212 if (_rtld_relocate_plt_object(obj, rela, NULL) < 0)
213 return -1;
214
215 return 0;
216 }
217