sys/kern/kern_ctf.c

   1 /*-
   2  * Copyright (c) 2008 John Birrell <jb@freebsd.org>
   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  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  *
  26  * $FreeBSD$
  27  */
  28
  29 /*
  30  * Note this file is included by both link_elf.c and link_elf_obj.c.
  31  *
  32  * The CTF header structure definition can't be used here because it's
  33  * (annoyingly) covered by the CDDL. We will just use a few bytes from
  34  * it as an integer array where we 'know' what they mean.
  35  */
  36 #define CTF_HDR_SIZE            36
  37 #define CTF_HDR_STRTAB_U32      7
  38 #define CTF_HDR_STRLEN_U32      8
  39
  40 #ifdef DDB_CTF
  41 static void *
  42 z_alloc(void *nil, u_int items, u_int size)
  43 {
  44         void *ptr;
  45
  46         ptr = malloc(items * size, M_TEMP, M_NOWAIT);
  47         return ptr;
  48 }
  49
  50 static void
  51 z_free(void *nil, void *ptr)
  52 {
  53         free(ptr, M_TEMP);
  54 }
  55
  56 #endif
  57
  58 static int
  59 link_elf_ctf_get(linker_file_t lf, linker_ctf_t *lc)
  60 {
  61 #ifdef DDB_CTF
  62         Elf_Ehdr *hdr = NULL;
  63         Elf_Shdr *shdr = NULL;
  64         caddr_t ctftab = NULL;
  65         caddr_t raw = NULL;
  66         caddr_t shstrtab = NULL;
  67         elf_file_t ef = (elf_file_t) lf;
  68         int flags;
  69         int i;
  70         int nbytes;
  71         int resid;
  72         int vfslocked;
  73         size_t sz;
  74         struct nameidata nd;
  75         struct thread *td = curthread;
  76         uint8_t ctf_hdr[CTF_HDR_SIZE];
  77 #endif
  78         int error = 0;
  79
  80         if (lf == NULL || lc == NULL)
  81                 return (EINVAL);
  82
  83         /* Set the defaults for no CTF present. That's not a crime! */
  84         bzero(lc, sizeof(*lc));
  85
  86 #ifdef DDB_CTF
  87         /*
  88          * First check if we've tried to load CTF data previously and the
  89          * CTF ELF section wasn't found. We flag that condition by setting
  90          * ctfcnt to -1. See below.
  91          */
  92         if (ef->ctfcnt < 0)
  93                 return (0);
  94
  95         /* Now check if we've already loaded the CTF data.. */
  96         if (ef->ctfcnt > 0) {
  97                 /* We only need to load once. */
  98                 lc->ctftab = ef->ctftab;
  99                 lc->ctfcnt = ef->ctfcnt;
 100                 lc->symtab = ef->ddbsymtab;
 101                 lc->strtab = ef->ddbstrtab;
 102                 lc->strcnt = ef->ddbstrcnt;
 103                 lc->nsym   = ef->ddbsymcnt;
 104                 lc->ctfoffp = (uint32_t **) &ef->ctfoff;
 105                 lc->typoffp = (uint32_t **) &ef->typoff;
 106                 lc->typlenp = &ef->typlen;
 107                 return (0);
 108         }
 109
 110         /*
 111          * We need to try reading the CTF data. Flag no CTF data present
 112          * by default and if we actually succeed in reading it, we'll
 113          * update ctfcnt to the number of bytes read.
 114          */
 115         ef->ctfcnt = -1;
 116
 117         NDINIT(&nd, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, lf->pathname, td);
 118         flags = FREAD;
 119         error = vn_open(&nd, &flags, 0, NULL);
 120         if (error)
 121                 return (error);
 122         vfslocked = NDHASGIANT(&nd);
 123         NDFREE(&nd, NDF_ONLY_PNBUF);
 124
 125         /* Allocate memory for the FLF header. */
 126         if ((hdr = malloc(sizeof(*hdr), M_LINKER, M_WAITOK)) == NULL) {
 127                 error = ENOMEM;
 128                 goto out;
 129         }
 130
 131         /* Read the ELF header. */
 132         if ((error = vn_rdwr(UIO_READ, nd.ni_vp, hdr, sizeof(*hdr),
 133             0, UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED, &resid,
 134             td)) != 0)
 135                 goto out;
 136
 137         /* Sanity check. */
 138         if (!IS_ELF(*hdr)) {
 139                 error = ENOEXEC;
 140                 goto out;
 141         }
 142
 143         nbytes = hdr->e_shnum * hdr->e_shentsize;
 144         if (nbytes == 0 || hdr->e_shoff == 0 ||
 145             hdr->e_shentsize != sizeof(Elf_Shdr)) {
 146                 error = ENOEXEC;
 147                 goto out;
 148         }
 149
 150         /* Allocate memory for all the section headers */
 151         if ((shdr = malloc(nbytes, M_LINKER, M_WAITOK)) == NULL) {
 152                 error = ENOMEM;
 153                 goto out;
 154         }
 155
 156         /* Read all the section headers */
 157         if ((error = vn_rdwr(UIO_READ, nd.ni_vp, (caddr_t)shdr, nbytes,
 158             hdr->e_shoff, UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
 159             &resid, td)) != 0)
 160                 goto out;
 161
 162         /*
 163          * We need to search for the CTF section by name, so if the
 164          * section names aren't present, then we can't locate the
 165          * .SUNW_ctf section containing the CTF data.
 166          */
 167         if (hdr->e_shstrndx == 0 || shdr[hdr->e_shstrndx].sh_type != SHT_STRTAB)
 168                 goto out;
 169
 170         /* Allocate memory to buffer the section header strings. */
 171         if ((shstrtab = malloc(shdr[hdr->e_shstrndx].sh_size, M_LINKER,
 172             M_WAITOK)) == NULL) {
 173                 error = ENOMEM;
 174                 goto out;
 175         }
 176
 177         /* Read the section header strings. */
 178         if ((error = vn_rdwr(UIO_READ, nd.ni_vp, shstrtab,
 179             shdr[hdr->e_shstrndx].sh_size, shdr[hdr->e_shstrndx].sh_offset,
 180             UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED, &resid,
 181             td)) != 0)
 182                 goto out;
 183
 184         /* Search for the section containing the CTF data. */
 185         for (i = 0; i < hdr->e_shnum; i++)
 186                 if (strcmp(".SUNW_ctf", shstrtab + shdr[i].sh_name) == 0)
 187                         break;
 188
 189         /* Check if the CTF section wasn't found. */
 190         if (i >= hdr->e_shnum)
 191                 goto out;
 192
 193         /* Read the CTF header. */
 194         if ((error = vn_rdwr(UIO_READ, nd.ni_vp, ctf_hdr, sizeof(ctf_hdr),
 195             shdr[i].sh_offset, UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred,
 196             NOCRED, &resid, td)) != 0)
 197                 goto out;
 198
 199         /* Check the CTF magic number. (XXX check for big endian!) */
 200         if (ctf_hdr[0] != 0xf1 || ctf_hdr[1] != 0xcf)
 201                 goto out;
 202
 203         /* Check if version 2. */
 204         if (ctf_hdr[2] != 2)
 205                 goto out;
 206
 207         /* Check if the data is compressed. */
 208         if ((ctf_hdr[3] & 0x1) != 0) {
 209                 uint32_t *u32 = (uint32_t *) ctf_hdr;
 210
 211                 /*
 212                  * The last two fields in the CTF header are the offset
 213                  * from the end of the header to the start of the string
 214                  * data and the length of that string data. se this
 215                  * information to determine the decompressed CTF data
 216                  * buffer required.
 217                  */
 218                 sz = u32[CTF_HDR_STRTAB_U32] + u32[CTF_HDR_STRLEN_U32] +
 219                     sizeof(ctf_hdr);
 220
 221                 /*
 222                  * Allocate memory for the compressed CTF data, including
 223                  * the header (which isn't compressed).
 224                  */
 225                 if ((raw = malloc(shdr[i].sh_size, M_LINKER, M_WAITOK)) == NULL) {
 226                         error = ENOMEM;
 227                         goto out;
 228                 }
 229         } else {
 230                 /*
 231                  * The CTF data is not compressed, so the ELF section
 232                  * size is the same as the buffer size required.
 233                  */
 234                 sz = shdr[i].sh_size;
 235         }
 236
 237         /*
 238          * Allocate memory to buffer the CTF data in it's decompressed
 239          * form.
 240          */
 241         if ((ctftab = malloc(sz, M_LINKER, M_WAITOK)) == NULL) {
 242                 error = ENOMEM;
 243                 goto out;
 244         }
 245
 246         /*
 247          * Read the CTF data into the raw buffer if compressed, or
 248          * directly into the CTF buffer otherwise.
 249          */
 250         if ((error = vn_rdwr(UIO_READ, nd.ni_vp, raw == NULL ? ctftab : raw,
 251             shdr[i].sh_size, shdr[i].sh_offset, UIO_SYSSPACE, IO_NODELOCKED,
 252             td->td_ucred, NOCRED, &resid, td)) != 0)
 253                 goto out;
 254
 255         /* Check if decompression is required. */
 256         if (raw != NULL) {
 257                 z_stream zs;
 258                 int ret;
 259
 260                 /*
 261                  * The header isn't compressed, so copy that into the
 262                  * CTF buffer first.
 263                  */
 264                 bcopy(ctf_hdr, ctftab, sizeof(ctf_hdr));
 265
 266                 /* Initialise the zlib structure. */
 267                 bzero(&zs, sizeof(zs));
 268                 zs.zalloc = z_alloc;
 269                 zs.zfree = z_free;
 270
 271                 if (inflateInit(&zs) != Z_OK) {
 272                         error = EIO;
 273                         goto out;
 274                 }
 275
 276                 zs.avail_in = shdr[i].sh_size - sizeof(ctf_hdr);
 277                 zs.next_in = ((uint8_t *) raw) + sizeof(ctf_hdr);
 278                 zs.avail_out = sz - sizeof(ctf_hdr);
 279                 zs.next_out = ((uint8_t *) ctftab) + sizeof(ctf_hdr);
 280                 if ((ret = inflate(&zs, Z_FINISH)) != Z_STREAM_END) {
 281                         printf("%s(%d): zlib inflate returned %d\n", __func__, __LINE__, ret);
 282                         error = EIO;
 283                         goto out;
 284                 }
 285         }
 286
 287         /* Got the CTF data! */
 288         ef->ctftab = ctftab;
 289         ef->ctfcnt = shdr[i].sh_size;
 290
 291         /* We'll retain the memory allocated for the CTF data. */
 292         ctftab = NULL;
 293
 294         /* Let the caller use the CTF data read. */
 295         lc->ctftab = ef->ctftab;
 296         lc->ctfcnt = ef->ctfcnt;
 297         lc->symtab = ef->ddbsymtab;
 298         lc->strtab = ef->ddbstrtab;
 299         lc->strcnt = ef->ddbstrcnt;
 300         lc->nsym   = ef->ddbsymcnt;
 301         lc->ctfoffp = (uint32_t **) &ef->ctfoff;
 302         lc->typoffp = (uint32_t **) &ef->typoff;
 303         lc->typlenp = &ef->typlen;
 304
 305 out:
 306         VOP_UNLOCK(nd.ni_vp, 0);
 307         vn_close(nd.ni_vp, FREAD, td->td_ucred, td);
 308         VFS_UNLOCK_GIANT(vfslocked);
 309
 310         if (hdr != NULL)
 311                 free(hdr, M_LINKER);
 312         if (shdr != NULL)
 313                 free(shdr, M_LINKER);
 314         if (shstrtab != NULL)
 315                 free(shstrtab, M_LINKER);
 316         if (ctftab != NULL)
 317                 free(ctftab, M_LINKER);
 318         if (raw != NULL)
 319                 free(raw, M_LINKER);
 320 #else
 321         error = EOPNOTSUPP;
 322 #endif
 323
 324         return (error);
 325 }