libelf: Fix elf_newdata when raw ELF file/image data is available.

When ELF data for a section has been read by elf_rawdata, data_read
and rawdata_base are set, but data_list_rear will not be set until the
data will be converted (by elf_getdata). elf_newdata would overwrite
the existing data in that case. Both elf_getdata and elf_update rely
on the fact that when data_list_rear is set they don't have to look
at the raw data anymore. So make sure we update the data list properly
before adding any new data and raw data is available in elf_newdata.

Add newdata test that calls elf_newdata before and after elf_rawdata
and elf_getdata and checks the new size and contents of the section.

Signed-off-by: Mark Wielaard <[email protected]>

1 files changed, 402 insertions, 0 deletions

diff --git a/tests/newdata.c b/tests/newdata.c
new file mode 100644
index 00000000..3cd872e0
--- /dev/null
+++ b/tests/newdata.c
@@ -0,0 +1,402 @@
+/* Test program for elf_newdata function.
+   Copyright (C) 2015 Red Hat, Inc.
+   This file is part of elfutils.
+
+   This file is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   elfutils is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <errno.h>
+#include <fcntl.h>
+#include <inttypes.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include ELFUTILS_HEADER(elf)
+#include <gelf.h>
+
+// Random data string (16 bytes).
+static char *DATA = "123456789ABCDEF";
+static size_t DATA_LEN = 16;
+
+static void
+add_section_data (Elf *elf, char *buf, size_t len)
+{
+  printf ("Adding %zd bytes.\n", len);
+
+  Elf_Scn *scn = elf_getscn (elf, 1);
+  if (scn == NULL)
+    {
+      printf ("couldn't get data section: %s\n", elf_errmsg (-1));
+      exit (1);
+    }
+
+  Elf_Data *data = elf_newdata (scn);
+  if (data == NULL)
+    {
+      printf ("cannot create newdata for section: %s\n", elf_errmsg (-1));
+      exit (1);
+    }
+
+  data->d_buf = buf;
+  data->d_type = ELF_T_BYTE;
+  data->d_size = len;
+  data->d_align = 1;
+  data->d_version = EV_CURRENT;
+
+  // Let the library compute the internal structure information.
+  if (elf_update (elf, ELF_C_NULL) < 0)
+    {
+      printf ("failure in elf_update(NULL): %s\n", elf_errmsg (-1));
+      exit (1);
+    }
+
+}
+
+static Elf *
+create_elf (int fd, int class, int use_mmap)
+{
+  Elf *elf = elf_begin (fd, use_mmap ? ELF_C_WRITE_MMAP : ELF_C_WRITE, NULL);
+  if (elf == NULL)
+    {
+      printf ("cannot create ELF descriptor: %s\n", elf_errmsg (-1));
+      exit (1);
+    }
+
+  // Create an ELF header.
+  if (gelf_newehdr (elf, class) == 0)
+    {
+      printf ("cannot create ELF header: %s\n", elf_errmsg (-1));
+      exit (1);
+    }
+
+  GElf_Ehdr ehdr_mem;
+  GElf_Ehdr *ehdr = gelf_getehdr (elf, &ehdr_mem);
+  if (ehdr == NULL)
+    {
+      printf ("cannot get ELF header: %s\n", elf_errmsg (-1));
+      exit (1);
+    }
+
+  // Initialize header.
+  ehdr->e_ident[EI_DATA] = class == ELFCLASS32 ? ELFDATA2LSB : ELFDATA2MSB;
+  ehdr->e_ident[EI_OSABI] = ELFOSABI_GNU;
+  ehdr->e_type = ET_NONE;
+  ehdr->e_machine = class == ELFCLASS32 ? EM_PPC : EM_X86_64;
+  ehdr->e_version = EV_CURRENT;
+
+  // Update the ELF header.
+  if (gelf_update_ehdr (elf, ehdr) == 0)
+    {
+      printf ("cannot update ELF header: %s\n", elf_errmsg (-1));
+      exit (1);
+    }
+
+  // Create a section.
+  Elf_Scn *scn = elf_newscn (elf);
+  if (scn == NULL)
+    {
+      printf ("cannot create new section: %s\n", elf_errmsg (-1));
+      exit (1);
+    }
+
+  GElf_Shdr shdr_mem;
+  GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem);
+  if (shdr == NULL)
+    {
+      printf ("cannot get header for data section: %s\n", elf_errmsg (-1));
+      exit (1);
+    }
+
+  shdr->sh_type = SHT_PROGBITS;
+  shdr->sh_flags = 0;
+  shdr->sh_addr = 0;
+  shdr->sh_link = SHN_UNDEF;
+  shdr->sh_info = SHN_UNDEF;
+  shdr->sh_addralign = 1;
+  shdr->sh_entsize = 1;
+  shdr->sh_name = 0;
+
+  // Finish section, update the header.
+  if (gelf_update_shdr (scn, shdr) == 0)
+    {
+      printf ("cannot update header for DATA section: %s\n", elf_errmsg (-1));
+      exit (1);
+    }
+
+  // Add some data to the section.
+  add_section_data (elf, DATA, DATA_LEN);
+
+  // Write everything to disk.
+  if (elf_update (elf, ELF_C_WRITE) < 0)
+    {
+      printf ("failure in elf_update(WRITE): %s\n", elf_errmsg (-1));
+      exit (1);
+    }
+
+  return elf;
+}
+
+static Elf *
+read_elf (int fd, int use_mmap)
+{
+  printf ("Reading ELF file\n");
+  Elf *elf = elf_begin (fd, use_mmap ? ELF_C_RDWR_MMAP : ELF_C_RDWR, NULL);
+  if (elf == NULL)
+    {
+      printf ("cannot create ELF descriptor read-again: %s\n", elf_errmsg (-1));
+      exit (1);
+    }
+
+  return elf;
+}
+
+static void
+check_section_size (Elf *elf, size_t size)
+{
+  Elf_Scn *scn = elf_getscn (elf, 1);
+  if (scn == NULL)
+    {
+      printf ("couldn't get data section: %s\n", elf_errmsg (-1));
+      exit (1);
+    }
+
+  GElf_Shdr shdr_mem;
+  GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem);
+  if (shdr == NULL)
+    {
+      printf ("cannot get header for DATA section: %s\n", elf_errmsg (-1));
+      exit (1);
+    }
+
+  if (shdr->sh_size == size)
+    printf ("OK %zd bytes.\n", size);
+  else
+    {
+      printf ("BAD size, expected %zd, got %" PRIu64 "\n",
+	      size, shdr->sh_size);
+      exit (-1);
+    }
+}
+
+static void
+check_section_data (Elf *elf, char *data, size_t len, size_t times)
+{
+  Elf_Scn *scn = elf_getscn (elf, 1);
+  if (scn == NULL)
+    {
+      printf ("couldn't get data section: %s\n", elf_errmsg (-1));
+      exit (1);
+    }
+
+  Elf_Data *d = NULL;
+  for (size_t i = 0; i < times; i++)
+    {
+      if (d == NULL || i * len >= d->d_off + d->d_size)
+	{
+	  d = elf_getdata (scn, d);
+	  if (d == NULL)
+	    {
+	      printf ("cannot get data for section item %zd: %s\n",
+		      i, elf_errmsg (-1));
+	      exit (1);
+	    }
+	  else
+	    printf ("OK, section data item %zd (d_off: %zd, d_size: %zd)\n",
+		    i, d->d_off, d->d_size);
+	}
+      char *d_data = (char *) d->d_buf + (len * i) - d->d_off;
+      printf ("%zd data (d_off: %zd, len * i: %zd): (%p + %zd) %s\n",
+	      i, d->d_off, len * i, d->d_buf, (len * i) - d->d_off, d_data);
+      if (memcmp (data, d_data, len) != 0)
+	{
+	  printf ("Got bad data in section for item %zd.\n", i);
+	  exit (1);
+	}
+    }
+}
+
+static void
+check_elf (int class, int use_mmap)
+{
+  static const char *fname;
+  if (class == ELFCLASS32)
+    fname = use_mmap ? "newdata.elf32.mmap" : "newdata.elf32";
+  else
+    fname = use_mmap ? "newdata.elf64.mmap" : "newdata.elf64";
+
+  printf ("\ncheck_elf: %s\n", fname);
+
+  int fd = open (fname, O_RDWR|O_CREAT|O_TRUNC, 00666);
+  if (fd == -1)
+    {
+      printf ("cannot create `%s': %s\n", fname, strerror (errno));
+      exit (1);
+    }
+
+  Elf *elf = create_elf (fd, class, use_mmap);
+  check_section_size (elf, DATA_LEN);
+  check_section_data (elf, DATA, DATA_LEN, 1);
+
+  // Add some more data (won't be written to disk).
+  add_section_data (elf, DATA, DATA_LEN);
+  check_section_size (elf, 2 * DATA_LEN);
+  check_section_data (elf, DATA, DATA_LEN, 2);
+
+  if (elf_end (elf) != 0)
+    {
+      printf ("failure in elf_end: %s\n", elf_errmsg (-1));
+      exit (1);
+    }
+
+  close (fd);
+
+  // Read the ELF from disk now.  And add new data directly.
+  fd = open (fname, O_RDONLY);
+  if (fd == -1)
+    {
+      printf ("cannot open `%s' read-only: %s\n", fname, strerror (errno));
+      exit (1);
+    }
+
+  elf = read_elf (fd, use_mmap);
+  check_section_size (elf, DATA_LEN);
+  // But don't check contents, that would read the data...
+
+  // Add some more data.
+  add_section_data (elf, DATA, DATA_LEN);
+  check_section_size (elf, 2 * DATA_LEN);
+  check_section_data (elf, DATA, DATA_LEN, 2);
+
+  // And some more.
+  add_section_data (elf, DATA, DATA_LEN);
+  check_section_size (elf, 3 * DATA_LEN);
+  check_section_data (elf, DATA, DATA_LEN, 3);
+
+  if (elf_end (elf) != 0)
+    {
+      printf ("failure in elf_end: %s\n", elf_errmsg (-1));
+      exit (1);
+    }
+
+  close (fd);
+
+  // Read the ELF from disk now.  And add new data after raw reading.
+  fd = open (fname, O_RDONLY);
+  if (fd == -1)
+    {
+      printf ("cannot open `%s' read-only: %s\n", fname, strerror (errno));
+      exit (1);
+    }
+
+  elf = read_elf (fd, use_mmap);
+  check_section_size (elf, DATA_LEN);
+  // But don't check contents, that would read the data...
+
+  // Get raw data before adding new data.
+  Elf_Scn *scn = elf_getscn (elf, 1);
+  if (scn == NULL)
+    {
+      printf ("couldn't get data section: %s\n", elf_errmsg (-1));
+      exit (1);
+    }
+
+  printf ("elf_rawdata\n");
+  Elf_Data *data = elf_rawdata (scn, NULL);
+  if (data == NULL)
+    {
+      printf ("couldn't get raw data from section: %s\n", elf_errmsg (-1));
+      exit (1);
+    }
+
+  if (data->d_size != DATA_LEN)
+    {
+      printf ("Unexpected Elf_Data: %zd", data->d_size);
+      exit (1);
+    }
+
+  // Now add more data.
+  add_section_data (elf, DATA, DATA_LEN);
+  check_section_size (elf, 2 * DATA_LEN);
+  check_section_data (elf, DATA, DATA_LEN, 2);
+
+  // And some more.
+  add_section_data (elf, DATA, DATA_LEN);
+  check_section_size (elf, 3 * DATA_LEN);
+  check_section_data (elf, DATA, DATA_LEN, 3);
+
+  if (elf_end (elf) != 0)
+    {
+      printf ("failure in elf_end: %s\n", elf_errmsg (-1));
+      exit (1);
+    }
+
+  close (fd);
+
+  // Read the ELF from disk now.  And add new data after data reading.
+  fd = open (fname, O_RDONLY);
+  if (fd == -1)
+    {
+      printf ("cannot open `%s' read-only: %s\n", fname, strerror (errno));
+      exit (1);
+    }
+
+  elf = read_elf (fd, use_mmap);
+  check_section_size (elf, DATA_LEN);
+  // Get (converted) data before adding new data.
+  check_section_data (elf, DATA, DATA_LEN, 1);
+
+  printf ("elf_getdata\n");
+
+  // Now add more data.
+  add_section_data (elf, DATA, DATA_LEN);
+  check_section_size (elf, 2 * DATA_LEN);
+  check_section_data (elf, DATA, DATA_LEN, 2);
+
+  // And some more.
+  add_section_data (elf, DATA, DATA_LEN);
+  check_section_size (elf, 3 * DATA_LEN);
+  check_section_data (elf, DATA, DATA_LEN, 3);
+
+  if (elf_end (elf) != 0)
+    {
+      printf ("failure in elf_end: %s\n", elf_errmsg (-1));
+      exit (1);
+    }
+
+  close (fd);
+
+  unlink (fname);
+}
+
+int
+main (int argc __attribute__ ((unused)), char *argv[] __attribute__ ((unused)))
+{
+  // Initialize libelf.
+  elf_version (EV_CURRENT);
+
+  // Fill holes with something non-zero to more easily spot bad data.
+  elf_fill ('X');
+
+  check_elf (ELFCLASS32, 0);
+  check_elf (ELFCLASS32, 1);
+  check_elf (ELFCLASS64, 0);
+  check_elf (ELFCLASS64, 1);
+
+  return 0;
+}