diff options
| author | Florian Weimer <fweimer@redhat.com> | 2016-06-23 20:01:40 +0200 |
|---|---|---|
| committer | Florian Weimer <fweimer@redhat.com> | 2016-06-23 20:01:52 +0200 |
| commit | db3476aff19b75c4fdefbe65fcd5f0a90588ba51 (patch) | |
| tree | 5cefd4971a0e6b5d5f9eacf6d3532c6aedc7b352 /libio/iofopncook.c | |
| parent | 64ba17317dc9343f0958755ad04af71ec3da637b (diff) | |
libio: Implement vtable verification [BZ #20191]
This commit puts all libio vtables in a dedicated, read-only ELF
section, so that they are consecutive in memory. Before any indirect
jump, the vtable pointer is checked against the section boundaries,
and the process is terminated if the vtable pointer does not fall into
the special ELF section.
To enable backwards compatibility, a special flag variable
(_IO_accept_foreign_vtables), protected by the pointer guard, avoids
process termination if libio stream object constructor functions have
been called earlier. Such constructor functions are called by the GCC
2.95 libstdc++ library, and this mechanism ensures compatibility with
old binaries. Existing callers inside glibc of these functions are
adjusted to call the original functions, not the wrappers which enable
vtable compatiblity.
The compatibility mechanism is used to enable passing FILE * objects
across a static dlopen boundary, too.
Diffstat (limited to 'libio/iofopncook.c')
| -rw-r--r-- | libio/iofopncook.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/libio/iofopncook.c b/libio/iofopncook.c index ceb444af7e..ae5df1707a 100644 --- a/libio/iofopncook.c +++ b/libio/iofopncook.c @@ -110,7 +110,7 @@ _IO_cookie_seekoff (_IO_FILE *fp, _IO_off64_t offset, int dir, int mode) } -static const struct _IO_jump_t _IO_cookie_jumps = { +static const struct _IO_jump_t _IO_cookie_jumps libio_vtable = { JUMP_INIT_DUMMY, JUMP_INIT(finish, _IO_file_finish), JUMP_INIT(overflow, _IO_file_overflow), @@ -151,13 +151,13 @@ void _IO_cookie_init (struct _IO_cookie_file *cfile, int read_write, void *cookie, _IO_cookie_io_functions_t io_functions) { - _IO_init (&cfile->__fp.file, 0); + _IO_init_internal (&cfile->__fp.file, 0); _IO_JUMPS (&cfile->__fp) = &_IO_cookie_jumps; cfile->__cookie = cookie; set_callbacks (&cfile->__io_functions, io_functions); - _IO_file_init (&cfile->__fp); + _IO_new_file_init_internal (&cfile->__fp); _IO_mask_flags (&cfile->__fp.file, read_write, _IO_NO_READS+_IO_NO_WRITES+_IO_IS_APPENDING); @@ -238,7 +238,7 @@ _IO_old_cookie_seek (_IO_FILE *fp, _IO_off64_t offset, int dir) return (ret == -1) ? _IO_pos_BAD : ret; } -static const struct _IO_jump_t _IO_old_cookie_jumps = { +static const struct _IO_jump_t _IO_old_cookie_jumps libio_vtable = { JUMP_INIT_DUMMY, JUMP_INIT(finish, _IO_file_finish), JUMP_INIT(overflow, _IO_file_overflow), |