1 /* $OpenBSD: boot_md.c,v 1.6 2022/01/31 05:43:22 guenther Exp $ */
2
3 /*
4 * Copyright (c) 1998 Per Fogelstrom, Opsycon AB
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
16 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
17 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
19 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 *
27 */
28
29 /*
30 * IMPORTANT: any functions below are NOT protected by SSP. Please
31 * do not add anything except what is required to reach GOT with
32 * an adjustment.
33 */
34
35 #define _DYN_LOADER
36
37 #include <sys/exec_elf.h>
38
39 #include "util.h"
40 #include "archdep.h" /* for RELOC_TAG */
41
42 #include "../../lib/csu/os-note-elf.h"
43
44 typedef Elf_RelA RELOC_TYPE;
45
46 /*
47 * Local decls.
48 */
49 void _dl_boot_bind(const long, long *, Elf_Dyn *) __boot;
50
51 void
_dl_boot_bind(const long sp,long * dl_data,Elf_Dyn * dynp)52 _dl_boot_bind(const long sp, long *dl_data, Elf_Dyn *dynp)
53 {
54 AuxInfo *auxstack;
55 long *stack;
56 int n, argc;
57 char **argv, **envp;
58 long loff;
59 const RELOC_TYPE *rend;
60 const RELOC_TYPE *dt_reloc; /* DT_RELA */
61 Elf_Addr dt_relocsz; /* DT_RELASZ */
62 Elf_Addr dt_pltgot;
63 Elf_Addr dt_pltrelsz;
64 const Elf_Sym *dt_symtab;
65 const RELOC_TYPE *dt_jmprel;
66
67 /*
68 * Scan argument and environment vectors. Find dynamic
69 * data vector put after them.
70 */
71 stack = (long *)sp;
72 argc = *stack++;
73 argv = (char **)stack;
74 envp = &argv[argc + 1];
75 stack = (long *)envp;
76 while (*stack++ != 0L)
77 ;
78
79 /*
80 * Zero out dl_data.
81 */
82 for (n = 0; n <= AUX_entry; n++)
83 dl_data[n] = 0;
84
85 /*
86 * Dig out auxiliary data set up by exec call. Move all known
87 * tags to an indexed local table for easy access.
88 */
89 for (auxstack = (AuxInfo *)stack; auxstack->au_id != AUX_null;
90 auxstack++) {
91 if (auxstack->au_id > AUX_entry)
92 continue;
93 dl_data[auxstack->au_id] = auxstack->au_v;
94 }
95 loff = dl_data[AUX_base]; /* XXX assumes ld.so is linked at 0x0 */
96
97 /*
98 * Scan the DYNAMIC section for the loader for the two items we need
99 */
100 dt_pltrelsz = dt_relocsz = dt_pltgot = 0;
101 dt_jmprel = dt_reloc = NULL;
102 dt_symtab = NULL;
103 while (dynp->d_tag != DT_NULL) {
104 /* first the tags that are pointers to be relocated */
105 if (dynp->d_tag == DT_PLTGOT)
106 dt_pltgot = dynp->d_un.d_ptr + loff;
107 else if (dynp->d_tag == DT_SYMTAB)
108 dt_symtab = (void *)(dynp->d_un.d_ptr + loff);
109 else if (dynp->d_tag == RELOC_TAG) /* DT_{RELA,REL} */
110 dt_reloc = (void *)(dynp->d_un.d_ptr + loff);
111 else if (dynp->d_tag == DT_JMPREL)
112 dt_jmprel = (void *)(dynp->d_un.d_ptr + loff);
113
114 /* Now for the tags that are just sizes or counts */
115 else if (dynp->d_tag == DT_PLTRELSZ)
116 dt_pltrelsz = dynp->d_un.d_val;
117 else if (dynp->d_tag == RELOC_TAG+1) /* DT_{RELA,REL}SZ */
118 dt_relocsz = dynp->d_un.d_val;
119 dynp++;
120 }
121
122 rend = (RELOC_TYPE *)((char *)dt_jmprel + dt_pltrelsz);
123 for (; dt_jmprel < rend; dt_jmprel++) {
124 Elf_Addr *ra;
125 const Elf_Sym *sp;
126
127 sp = dt_symtab + ELF_R_SYM(dt_jmprel->r_info);
128 ra = (Elf_Addr *)(dt_jmprel->r_offset + loff);
129 ra[0] = loff + sp->st_value + dt_jmprel->r_addend;
130 ra[1] = dt_pltgot;
131 }
132
133 rend = (RELOC_TYPE *)((char *)dt_reloc + dt_relocsz);
134 for (; dt_reloc < rend; dt_reloc++) {
135 Elf_Addr *ra;
136 const Elf_Sym *sp;
137
138 sp = dt_symtab + ELF_R_SYM(dt_reloc->r_info);
139 ra = (Elf_Addr *)(dt_reloc->r_offset + loff);
140 *ra = loff + sp->st_value + dt_reloc->r_addend;
141 }
142 }
143