libio: Remove the usage of __libc_IO_vtables

Instead of using a special ELF section along with a linker script
directive to put the IO vtables within the RELRO section, the libio
vtables are all moved to an array marked as data.relro (so linker
will place in the RELRO segment without the need of extra directives).

To avoid static linking namespace issues and including all vtable
referenced objects, all required function pointers are set to weak alias.

Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>

1 files changed, 4 insertions, 77 deletions

diff --git a/libio/fileops.c b/libio/fileops.c
index b75d748539..58c9e985e4 100644
--- a/libio/fileops.c
+++ b/libio/fileops.c
@@ -815,7 +815,7 @@ _IO_new_file_sync (FILE *fp)
 }
 libc_hidden_ver (_IO_new_file_sync, _IO_file_sync)
 
-static int
+int
 _IO_file_sync_mmap (FILE *fp)
 {
   if (fp->_IO_read_ptr != fp->_IO_read_end)
@@ -1109,7 +1109,7 @@ _IO_file_seekoff_mmap (FILE *fp, off64_t offset, int dir, int mode)
   return offset;
 }
 
-static off64_t
+off64_t
 _IO_file_seekoff_maybe_mmap (FILE *fp, off64_t offset, int dir,
 			     int mode)
 {
@@ -1360,7 +1360,7 @@ _IO_file_xsgetn (FILE *fp, void *data, size_t n)
 }
 libc_hidden_def (_IO_file_xsgetn)
 
-static size_t
+size_t
 _IO_file_xsgetn_mmap (FILE *fp, void *data, size_t n)
 {
   size_t have;
@@ -1405,7 +1405,7 @@ _IO_file_xsgetn_mmap (FILE *fp, void *data, size_t n)
   return s - (char *) data;
 }
 
-static size_t
+size_t
 _IO_file_xsgetn_maybe_mmap (FILE *fp, void *data, size_t n)
 {
   /* We only get here if this is the first attempt to read something.
@@ -1428,76 +1428,3 @@ versioned_symbol (libc, _IO_new_file_seekoff, _IO_file_seekoff, GLIBC_2_1);
 versioned_symbol (libc, _IO_new_file_underflow, _IO_file_underflow, GLIBC_2_1);
 versioned_symbol (libc, _IO_new_file_write, _IO_file_write, GLIBC_2_1);
 versioned_symbol (libc, _IO_new_file_xsputn, _IO_file_xsputn, GLIBC_2_1);
-
-const struct _IO_jump_t _IO_file_jumps libio_vtable =
-{
-  JUMP_INIT_DUMMY,
-  JUMP_INIT(finish, _IO_file_finish),
-  JUMP_INIT(overflow, _IO_file_overflow),
-  JUMP_INIT(underflow, _IO_file_underflow),
-  JUMP_INIT(uflow, _IO_default_uflow),
-  JUMP_INIT(pbackfail, _IO_default_pbackfail),
-  JUMP_INIT(xsputn, _IO_file_xsputn),
-  JUMP_INIT(xsgetn, _IO_file_xsgetn),
-  JUMP_INIT(seekoff, _IO_new_file_seekoff),
-  JUMP_INIT(seekpos, _IO_default_seekpos),
-  JUMP_INIT(setbuf, _IO_new_file_setbuf),
-  JUMP_INIT(sync, _IO_new_file_sync),
-  JUMP_INIT(doallocate, _IO_file_doallocate),
-  JUMP_INIT(read, _IO_file_read),
-  JUMP_INIT(write, _IO_new_file_write),
-  JUMP_INIT(seek, _IO_file_seek),
-  JUMP_INIT(close, _IO_file_close),
-  JUMP_INIT(stat, _IO_file_stat),
-  JUMP_INIT(showmanyc, _IO_default_showmanyc),
-  JUMP_INIT(imbue, _IO_default_imbue)
-};
-libc_hidden_data_def (_IO_file_jumps)
-
-const struct _IO_jump_t _IO_file_jumps_mmap libio_vtable =
-{
-  JUMP_INIT_DUMMY,
-  JUMP_INIT(finish, _IO_file_finish),
-  JUMP_INIT(overflow, _IO_file_overflow),
-  JUMP_INIT(underflow, _IO_file_underflow_mmap),
-  JUMP_INIT(uflow, _IO_default_uflow),
-  JUMP_INIT(pbackfail, _IO_default_pbackfail),
-  JUMP_INIT(xsputn, _IO_new_file_xsputn),
-  JUMP_INIT(xsgetn, _IO_file_xsgetn_mmap),
-  JUMP_INIT(seekoff, _IO_file_seekoff_mmap),
-  JUMP_INIT(seekpos, _IO_default_seekpos),
-  JUMP_INIT(setbuf, (_IO_setbuf_t) _IO_file_setbuf_mmap),
-  JUMP_INIT(sync, _IO_file_sync_mmap),
-  JUMP_INIT(doallocate, _IO_file_doallocate),
-  JUMP_INIT(read, _IO_file_read),
-  JUMP_INIT(write, _IO_new_file_write),
-  JUMP_INIT(seek, _IO_file_seek),
-  JUMP_INIT(close, _IO_file_close_mmap),
-  JUMP_INIT(stat, _IO_file_stat),
-  JUMP_INIT(showmanyc, _IO_default_showmanyc),
-  JUMP_INIT(imbue, _IO_default_imbue)
-};
-
-const struct _IO_jump_t _IO_file_jumps_maybe_mmap libio_vtable =
-{
-  JUMP_INIT_DUMMY,
-  JUMP_INIT(finish, _IO_file_finish),
-  JUMP_INIT(overflow, _IO_file_overflow),
-  JUMP_INIT(underflow, _IO_file_underflow_maybe_mmap),
-  JUMP_INIT(uflow, _IO_default_uflow),
-  JUMP_INIT(pbackfail, _IO_default_pbackfail),
-  JUMP_INIT(xsputn, _IO_new_file_xsputn),
-  JUMP_INIT(xsgetn, _IO_file_xsgetn_maybe_mmap),
-  JUMP_INIT(seekoff, _IO_file_seekoff_maybe_mmap),
-  JUMP_INIT(seekpos, _IO_default_seekpos),
-  JUMP_INIT(setbuf, (_IO_setbuf_t) _IO_file_setbuf_mmap),
-  JUMP_INIT(sync, _IO_new_file_sync),
-  JUMP_INIT(doallocate, _IO_file_doallocate),
-  JUMP_INIT(read, _IO_file_read),
-  JUMP_INIT(write, _IO_new_file_write),
-  JUMP_INIT(seek, _IO_file_seek),
-  JUMP_INIT(close, _IO_file_close),
-  JUMP_INIT(stat, _IO_file_stat),
-  JUMP_INIT(showmanyc, _IO_default_showmanyc),
-  JUMP_INIT(imbue, _IO_default_imbue)
-};