include/elf/internal.h

   1 /* ELF support for BFD.
   2    Copyright (C) 1991-2016 Free Software Foundation, Inc.
   3
   4    Written by Fred Fish @ Cygnus Support, from information published
   5    in "UNIX System V Release 4, Programmers Guide: ANSI C and
   6    Programming Support Tools".
   7
   8    This file is part of BFD, the Binary File Descriptor library.
   9
  10    This program is free software; you can redistribute it and/or modify
  11    it under the terms of the GNU General Public License as published by
  12    the Free Software Foundation; either version 3 of the License, or
  13    (at your option) any later version.
  14
  15    This program is distributed in the hope that it will be useful,
  16    but WITHOUT ANY WARRANTY; without even the implied warranty of
  17    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18    GNU General Public License for more details.
  19
  20    You should have received a copy of the GNU General Public License
  21    along with this program; if not, write to the Free Software
  22    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  23    MA 02110-1301, USA.  */
  24
  25 /* This file is part of ELF support for BFD, and contains the portions
  26    that describe how ELF is represented internally in the BFD library.
  27    I.E. it describes the in-memory representation of ELF.  It requires
  28    the elf-common.h file which contains the portions that are common to
  29    both the internal and external representations.  */
  30
  31 /* NOTE that these structures are not kept in the same order as they appear
  32    in the object file.  In some cases they've been reordered for more optimal
  33    packing under various circumstances.  */
  34
  35 #ifndef _ELF_INTERNAL_H
  36 #define _ELF_INTERNAL_H
  37
  38 /* Special section indices, which may show up in st_shndx fields, among
  39    other places.  */
  40
  41 #undef SHN_UNDEF
  42 #undef SHN_LORESERVE
  43 #undef SHN_LOPROC
  44 #undef SHN_HIPROC
  45 #undef SHN_LOOS
  46 #undef SHN_HIOS
  47 #undef SHN_ABS
  48 #undef SHN_COMMON
  49 #undef SHN_XINDEX
  50 #undef SHN_HIRESERVE
  51 #define SHN_UNDEF       0               /* Undefined section reference */
  52 #define SHN_LORESERVE   (-0x100u)       /* Begin range of reserved indices */
  53 #define SHN_LOPROC      (-0x100u)       /* Begin range of appl-specific */
  54 #define SHN_HIPROC      (-0xE1u)        /* End range of appl-specific */
  55 #define SHN_LOOS        (-0xE0u)        /* OS specific semantics, lo */
  56 #define SHN_HIOS        (-0xC1u)        /* OS specific semantics, hi */
  57 #define SHN_ABS         (-0xFu)         /* Associated symbol is absolute */
  58 #define SHN_COMMON      (-0xEu)         /* Associated symbol is in common */
  59 #define SHN_XINDEX      (-0x1u)         /* Section index is held elsewhere */
  60 #define SHN_HIRESERVE   (-0x1u)         /* End range of reserved indices */
  61 #define SHN_BAD         (-0x101u)       /* Used internally by bfd */
  62
  63 /* ELF Header */
  64
  65 #define EI_NIDENT       16              /* Size of e_ident[] */
  66
  67 typedef struct elf_internal_ehdr {
  68   unsigned char         e_ident[EI_NIDENT]; /* ELF "magic number" */
  69   bfd_vma               e_entry;        /* Entry point virtual address */
  70   bfd_size_type         e_phoff;        /* Program header table file offset */
  71   bfd_size_type         e_shoff;        /* Section header table file offset */
  72   unsigned long         e_version;      /* Identifies object file version */
  73   unsigned long         e_flags;        /* Processor-specific flags */
  74   unsigned short        e_type;         /* Identifies object file type */
  75   unsigned short        e_machine;      /* Specifies required architecture */
  76   unsigned int          e_ehsize;       /* ELF header size in bytes */
  77   unsigned int          e_phentsize;    /* Program header table entry size */
  78   unsigned int          e_phnum;        /* Program header table entry count */
  79   unsigned int          e_shentsize;    /* Section header table entry size */
  80   unsigned int          e_shnum;        /* Section header table entry count */
  81   unsigned int          e_shstrndx;     /* Section header string table index */
  82 } Elf_Internal_Ehdr;
  83
  84 /* Program header */
  85
  86 struct elf_internal_phdr {
  87   unsigned long p_type;                 /* Identifies program segment type */
  88   unsigned long p_flags;                /* Segment flags */
  89   bfd_vma       p_offset;               /* Segment file offset */
  90   bfd_vma       p_vaddr;                /* Segment virtual address */
  91   bfd_vma       p_paddr;                /* Segment physical address */
  92   bfd_vma       p_filesz;               /* Segment size in file */
  93   bfd_vma       p_memsz;                /* Segment size in memory */
  94   bfd_vma       p_align;                /* Segment alignment, file & memory */
  95 };
  96
  97 typedef struct elf_internal_phdr Elf_Internal_Phdr;
  98
  99 /* Section header */
 100
 101 typedef struct elf_internal_shdr {
 102   unsigned int  sh_name;                /* Section name, index in string tbl */
 103   unsigned int  sh_type;                /* Type of section */
 104   bfd_vma       sh_flags;               /* Miscellaneous section attributes */
 105   bfd_vma       sh_addr;                /* Section virtual addr at execution */
 106   file_ptr      sh_offset;              /* Section file offset */
 107   bfd_size_type sh_size;                /* Size of section in bytes */
 108   unsigned int  sh_link;                /* Index of another section */
 109   unsigned int  sh_info;                /* Additional section information */
 110   bfd_vma       sh_addralign;           /* Section alignment */
 111   bfd_size_type sh_entsize;             /* Entry size if section holds table */
 112
 113   /* The internal rep also has some cached info associated with it. */
 114   asection *    bfd_section;            /* Associated BFD section.  */
 115   unsigned char *contents;              /* Section contents.  */
 116 } Elf_Internal_Shdr;
 117
 118 /* Compression header */
 119
 120 typedef struct elf_internal_chdr {
 121   unsigned int  ch_type;                /* Type of compression */
 122   bfd_size_type ch_size;                /* Size of uncompressed data in bytes */
 123   bfd_vma       ch_addralign;           /* Alignment of uncompressed data */
 124 } Elf_Internal_Chdr;
 125
 126 /* Symbol table entry */
 127
 128 struct elf_internal_sym {
 129   bfd_vma       st_value;               /* Value of the symbol */
 130   bfd_vma       st_size;                /* Associated symbol size */
 131   unsigned long st_name;                /* Symbol name, index in string tbl */
 132   unsigned char st_info;                /* Type and binding attributes */
 133   unsigned char st_other;               /* Visibilty, and target specific */
 134   unsigned char st_target_internal;     /* Internal-only information */
 135   unsigned int  st_shndx;               /* Associated section index */
 136 };
 137
 138 typedef struct elf_internal_sym Elf_Internal_Sym;
 139
 140 /* Note segments */
 141
 142 typedef struct elf_internal_note {
 143   unsigned long namesz;                 /* Size of entry's owner string */
 144   unsigned long descsz;                 /* Size of the note descriptor */
 145   unsigned long type;                   /* Interpretation of the descriptor */
 146   char *        namedata;               /* Start of the name+desc data */
 147   char *        descdata;               /* Start of the desc data */
 148   bfd_vma       descpos;                /* File offset of the descdata */
 149 } Elf_Internal_Note;
 150
 151 /* Relocation Entries */
 152
 153 typedef struct elf_internal_rela {
 154   bfd_vma       r_offset;       /* Location at which to apply the action */
 155   bfd_vma       r_info;         /* Index and Type of relocation */
 156   bfd_vma       r_addend;       /* Constant addend used to compute value */
 157 } Elf_Internal_Rela;
 158
 159 /* dynamic section structure */
 160
 161 typedef struct elf_internal_dyn {
 162   /* This needs to support 64-bit values in elf64.  */
 163   bfd_vma d_tag;                /* entry tag value */
 164   union {
 165     /* This needs to support 64-bit values in elf64.  */
 166     bfd_vma     d_val;
 167     bfd_vma     d_ptr;
 168   } d_un;
 169 } Elf_Internal_Dyn;
 170
 171 /* This structure appears in a SHT_GNU_verdef section.  */
 172
 173 typedef struct elf_internal_verdef {
 174   unsigned short vd_version;    /* Version number of structure.  */
 175   unsigned short vd_flags;      /* Flags (VER_FLG_*).  */
 176   unsigned short vd_ndx;        /* Version index.  */
 177   unsigned short vd_cnt;        /* Number of verdaux entries.  */
 178   unsigned long  vd_hash;       /* Hash of name.  */
 179   unsigned long  vd_aux;        /* Offset to verdaux entries.  */
 180   unsigned long  vd_next;       /* Offset to next verdef.  */
 181
 182   /* These fields are set up when BFD reads in the structure.  FIXME:
 183      It would be cleaner to store these in a different structure.  */
 184   bfd                         *vd_bfd;          /* BFD.  */
 185   const char                  *vd_nodename;     /* Version name.  */
 186   struct elf_internal_verdef  *vd_nextdef;      /* vd_next as pointer.  */
 187   struct elf_internal_verdaux *vd_auxptr;       /* vd_aux as pointer.  */
 188   unsigned int                 vd_exp_refno;    /* Used by the linker.  */
 189 } Elf_Internal_Verdef;
 190
 191 /* This structure appears in a SHT_GNU_verdef section.  */
 192
 193 typedef struct elf_internal_verdaux {
 194   unsigned long vda_name;       /* String table offset of name.  */
 195   unsigned long vda_next;       /* Offset to next verdaux.  */
 196
 197   /* These fields are set up when BFD reads in the structure.  FIXME:
 198      It would be cleaner to store these in a different structure.  */
 199   const char *vda_nodename;                     /* vda_name as pointer.  */
 200   struct elf_internal_verdaux *vda_nextptr;     /* vda_next as pointer.  */
 201 } Elf_Internal_Verdaux;
 202
 203 /* This structure appears in a SHT_GNU_verneed section.  */
 204
 205 typedef struct elf_internal_verneed {
 206   unsigned short vn_version;    /* Version number of structure.  */
 207   unsigned short vn_cnt;        /* Number of vernaux entries.  */
 208   unsigned long  vn_file;       /* String table offset of library name.  */
 209   unsigned long  vn_aux;        /* Offset to vernaux entries.  */
 210   unsigned long  vn_next;       /* Offset to next verneed.  */
 211
 212   /* These fields are set up when BFD reads in the structure.  FIXME:
 213      It would be cleaner to store these in a different structure.  */
 214   bfd                         *vn_bfd;          /* BFD.  */
 215   const char                  *vn_filename;     /* vn_file as pointer.  */
 216   struct elf_internal_vernaux *vn_auxptr;       /* vn_aux as pointer.  */
 217   struct elf_internal_verneed *vn_nextref;      /* vn_nextref as pointer.  */
 218 } Elf_Internal_Verneed;
 219
 220 /* This structure appears in a SHT_GNU_verneed section.  */
 221
 222 typedef struct elf_internal_vernaux {
 223   unsigned long  vna_hash;      /* Hash of dependency name.  */
 224   unsigned short vna_flags;     /* Flags (VER_FLG_*).  */
 225   unsigned short vna_other;     /* Unused.  */
 226   unsigned long  vna_name;      /* String table offset to version name.  */
 227   unsigned long  vna_next;      /* Offset to next vernaux.  */
 228
 229   /* These fields are set up when BFD reads in the structure.  FIXME:
 230      It would be cleaner to store these in a different structure.  */
 231   const char                  *vna_nodename;    /* vna_name as pointer.  */
 232   struct elf_internal_vernaux *vna_nextptr;     /* vna_next as pointer.  */
 233 } Elf_Internal_Vernaux;
 234
 235 /* This structure appears in a SHT_GNU_versym section.  This is not a
 236    standard ELF structure; ELF just uses Elf32_Half.  */
 237
 238 typedef struct elf_internal_versym {
 239   unsigned short vs_vers;
 240 } Elf_Internal_Versym;
 241
 242 /* Structure for syminfo section.  */
 243 typedef struct
 244 {
 245   unsigned short int    si_boundto;
 246   unsigned short int    si_flags;
 247 } Elf_Internal_Syminfo;
 248
 249 /* This structure appears on the stack and in NT_AUXV core file notes.  */
 250 typedef struct
 251 {
 252   bfd_vma a_type;
 253   bfd_vma a_val;
 254 } Elf_Internal_Auxv;
 255
 256
 257 /* This structure is used to describe how sections should be assigned
 258    to program segments.  */
 259
 260 struct elf_segment_map
 261 {
 262   /* Next program segment.  */
 263   struct elf_segment_map *next;
 264   /* Program segment type.  */
 265   unsigned long p_type;
 266   /* Program segment flags.  */
 267   unsigned long p_flags;
 268   /* Program segment physical address.  */
 269   bfd_vma p_paddr;
 270   /* Program segment virtual address offset from section vma.  */
 271   bfd_vma p_vaddr_offset;
 272   /* Program segment alignment.  */
 273   bfd_vma p_align;
 274   /* Segment size in file and memory */
 275   bfd_vma p_size;
 276   /* Required size of filehdr + phdrs, if non-zero */
 277   bfd_vma header_size;
 278   /* Whether the p_flags field is valid; if not, the flags are based
 279      on the section flags.  */
 280   unsigned int p_flags_valid : 1;
 281   /* Whether the p_paddr field is valid; if not, the physical address
 282      is based on the section lma values.  */
 283   unsigned int p_paddr_valid : 1;
 284   /* Whether the p_align field is valid; if not, PT_LOAD segment
 285      alignment is based on the default maximum page size.  */
 286   unsigned int p_align_valid : 1;
 287   /* Whether the p_size field is valid; if not, the size are based
 288      on the section sizes.  */
 289   unsigned int p_size_valid : 1;
 290   /* Whether this segment includes the file header.  */
 291   unsigned int includes_filehdr : 1;
 292   /* Whether this segment includes the program headers.  */
 293   unsigned int includes_phdrs : 1;
 294   /* Number of sections (may be 0).  */
 295   unsigned int count;
 296   /* Sections.  Actual number of elements is in count field.  */
 297   asection *sections[1];
 298 };
 299
 300 /* .tbss is special.  It doesn't contribute memory space to normal
 301    segments and it doesn't take file space in normal segments.  */
 302 #define ELF_TBSS_SPECIAL(sec_hdr, segment)                      \
 303   (((sec_hdr)->sh_flags & SHF_TLS) != 0                         \
 304    && (sec_hdr)->sh_type == SHT_NOBITS                          \
 305    && (segment)->p_type != PT_TLS)
 306
 307 #define ELF_SECTION_SIZE(sec_hdr, segment)                      \
 308   (ELF_TBSS_SPECIAL(sec_hdr, segment) ? 0 : (sec_hdr)->sh_size)
 309
 310 /* Decide if the section SEC_HDR is in SEGMENT.  If CHECK_VMA, then
 311    VMAs are checked for alloc sections.  If STRICT, then a zero size
 312    section won't match at the end of a segment, unless the segment
 313    is also zero size.  Regardless of STRICT and CHECK_VMA, zero size
 314    sections won't match at the start or end of PT_DYNAMIC, unless
 315    PT_DYNAMIC is itself zero sized.  */
 316 #define ELF_SECTION_IN_SEGMENT_1(sec_hdr, segment, check_vma, strict)   \
 317   ((/* Only PT_LOAD, PT_GNU_RELRO and PT_TLS segments can contain       \
 318        SHF_TLS sections.  */                                            \
 319     ((((sec_hdr)->sh_flags & SHF_TLS) != 0)                             \
 320      && ((segment)->p_type == PT_TLS                                    \
 321          || (segment)->p_type == PT_GNU_RELRO                           \
 322          || (segment)->p_type == PT_LOAD))                              \
 323     /* PT_TLS segment contains only SHF_TLS sections, PT_PHDR no        \
 324        sections at all.  */                                             \
 325     || (((sec_hdr)->sh_flags & SHF_TLS) == 0                            \
 326         && (segment)->p_type != PT_TLS                                  \
 327         && (segment)->p_type != PT_PHDR))                               \
 328    /* PT_LOAD and similar segments only have SHF_ALLOC sections.  */    \
 329    && !(((sec_hdr)->sh_flags & SHF_ALLOC) == 0                          \
 330         && ((segment)->p_type == PT_LOAD                                \
 331             || (segment)->p_type == PT_DYNAMIC                          \
 332             || (segment)->p_type == PT_GNU_EH_FRAME                     \
 333             || (segment)->p_type == PT_GNU_RELRO                        \
 334             || (segment)->p_type == PT_GNU_STACK))                      \
 335    /* Any section besides one of type SHT_NOBITS must have file         \
 336       offsets within the segment.  */                                   \
 337    && ((sec_hdr)->sh_type == SHT_NOBITS                                 \
 338        || ((bfd_vma) (sec_hdr)->sh_offset >= (segment)->p_offset        \
 339            && (!(strict)                                                \
 340                || ((sec_hdr)->sh_offset - (segment)->p_offset           \
 341                    <= (segment)->p_filesz - 1))                         \
 342            && (((sec_hdr)->sh_offset - (segment)->p_offset              \
 343                 + ELF_SECTION_SIZE(sec_hdr, segment))                   \
 344                <= (segment)->p_filesz)))                                \
 345    /* SHF_ALLOC sections must have VMAs within the segment.  */         \
 346    && (!(check_vma)                                                     \
 347        || ((sec_hdr)->sh_flags & SHF_ALLOC) == 0                        \
 348        || ((sec_hdr)->sh_addr >= (segment)->p_vaddr                     \
 349            && (!(strict)                                                \
 350                || ((sec_hdr)->sh_addr - (segment)->p_vaddr              \
 351                    <= (segment)->p_memsz - 1))                          \
 352            && (((sec_hdr)->sh_addr - (segment)->p_vaddr                 \
 353                 + ELF_SECTION_SIZE(sec_hdr, segment))                   \
 354                <= (segment)->p_memsz)))                                 \
 355    /* No zero size sections at start or end of PT_DYNAMIC.  */          \
 356    && ((segment)->p_type != PT_DYNAMIC                                  \
 357        || (sec_hdr)->sh_size != 0                                       \
 358        || (segment)->p_memsz == 0                                       \
 359        || (((sec_hdr)->sh_type == SHT_NOBITS                            \
 360             || ((bfd_vma) (sec_hdr)->sh_offset > (segment)->p_offset    \
 361                 && ((sec_hdr)->sh_offset - (segment)->p_offset          \
 362                     < (segment)->p_filesz)))                            \
 363            && (((sec_hdr)->sh_flags & SHF_ALLOC) == 0                   \
 364                || ((sec_hdr)->sh_addr > (segment)->p_vaddr              \
 365                    && ((sec_hdr)->sh_addr - (segment)->p_vaddr          \
 366                        < (segment)->p_memsz))))))
 367
 368 #define ELF_SECTION_IN_SEGMENT(sec_hdr, segment)                        \
 369   (ELF_SECTION_IN_SEGMENT_1 (sec_hdr, segment, 1, 0))
 370
 371 #define ELF_SECTION_IN_SEGMENT_STRICT(sec_hdr, segment)                 \
 372   (ELF_SECTION_IN_SEGMENT_1 (sec_hdr, segment, 1, 1))
 373
 374 #endif /* _ELF_INTERNAL_H */