Use the functions in linker_phdr.c to load the PT_LOAD segments
in memory, and toggle their mapping's writable protection bit
as needed. In particular:
- when loading a library, load the segments then unprotected
them to allow relocations to work.
- when relocating the linker of the executable, unprotect
the segments loaded by the kernel to make relocations work
too.
- after all relocations are done, re-protect the segments,
and apply GNU RELRO protection if needed.
- just before calling the destructors, undo the GNU RELRO
protection.
Change-Id: I50e709f03958204b8d6140c0f51ebe24fe089a1b
This patch changes the definition of the 'load_offset' field
in struct soinfo. The field is renamed because it is not the
basic load bias to add to every p_vaddr value read from the ELF
file to get the corresponding memory address.
This also slightly simplifies the relocation code.
+ Fix for proper load_bias computation for relocatable executables.
Change-Id: I72502c75a70751cba324deee7d313ae61f96609e
This patch introduces two new source files containing a set of functions
to manage the program header table in an ELF binary, including the ability
to load PT_LOAD segments, and apply PT_GNU_RELRO protection.
Note: the files are not used currently, this will appear in a series
of future patches that will gradually modify linker.c to use
the phdr_table_xxx functions properly.
Change-Id: Ia3d4c1ff5fc3e265d8258b64b492f4e643f51bdc
This patch adds to make the linker a little bit easier to understand
by making all functions that acts on a sofino object with a soinfo_
prefix.
This is to more easily distinguish functions that operate on global
state, and those that operate on individual libraries.
This should be purely stylistic, i.e. no feature/behaviour change.
Change-Id: Ie510d13d743aa4317644caefa9910b8af7e84f44
Before changing mmap() permission to PROT_NONE in alloc_mem_region(),
such libraries once worked with a bug that uses mmap'ed region outside of
memory region allocated by alloc_mem_region(). This possibly incurs
SIGSEGV because it can overwrite memory region of previously loaded
library, but it sometimes worked, depending on loading order.
After PROT_NONE, this caused SIGSEGV earlier during calculation of
si->phdr in load_library(), but this was fixed by:
75917c84d1 Use mmap to read an ...
Now the behaviour is the same as before applying PROT_NONE in
alloc_mem_region().
This CL fixed the original issue, supporting shared libraries that have
non-zero p_vaddr in first (= with lowest p_vaddr) PT_LOAD segment.
Bug: 6561258
Change-Id: Ib6176dd3e44c4d99a340eb1cbd16fb037586b0bc
Add support for PT_GNU_RELRO. This allows the static linker to
indicate that certain regions of memory should be marked as
"read-only" after dynamic linking is complete.
See:
* http://www.akkadia.org/drepper/nonselsec.pdf (section 6)
* http://tk-blog.blogspot.com/2009/02/relro-not-so-well-known-memory.html
Note that this change has no effect on Android right now, because
we don't compile our code with relro enabled.
Change-Id: I6541f8775367e8558b4388f7d105b1ae6e8f046b
We don't have a toolchain anymore, we don't have working original
kernel headers, and nobody is maintaining this so there is really
no point in keeping this here. Details of the patch:
- removed code paths from Android.mk files related to the SuperH
architecture ("sh")
- removed libc/arch-sh, linker/arch-sh, libc/kernel/arch-sh
- simplified libc/SYSCALLS.TXT
- simplified the scripts in libc/tools/ and libc/kernel/tools
Change-Id: I26b0e1422bdc347489e4573e2fbec0e402f75560
Signed-off-by: David 'Digit' Turner <digit@android.com>
This change makes linker handling of .preinit_array compliant with the
System V ABI:
"These [pre-initialization] functions are executed after the dynamic linker has
built the process image and performed relocations but before any shared object
initialization functions."
http://www.sco.com/developers/gabi/latest/ch5.dynamic.html#init_fini
Change-Id: Iebfee22bb1ebe1d7c7e69cb4686e4ebae0dfc4bb
Previously, the linker always loaded itself into the same
location in memory, which inhibited the effectiveness of Android's
ASLR implementation. Modify the linker code so it can be relocatable
and link itself at runtime.
Change-Id: Ia80273d7a00ff648b4da545f4b69debee6343968
Previously, the linker always loaded itself into the same
location in memory, which inhibited the effectiveness of Android's
ASLR implementation. Modify the linker code so it can be relocatable
and link itself at runtime.
Change-Id: I90d064743abdd29450ac0482ed28752b2196286c
In 48527c3f74, we modified the soinfo
structure to remove an unnecessary variable. However, third party
programs seem to be relying on the structure not changing.
Add a dummy variable back into place to preserve structure.
Bug: 5064106
Change-Id: I3014dda1a46e624644b09e156c3e9381ba3729bd
Currently, the Android linker is placing shared libraries into
a well-known spot in memory. This is interfering with the kernel's
ASLR support.
This change stops forcing non-prelinked libraries into a particular
address space.
Also, get rid of FLAG_PRELINKED. As best I can tell, this flag
is never used.
Change-Id: I527af12fb54f821c2b5ca7693dbf63d022f8f4ae
The previous implementation of this flag was broken--it behaved identically
to RTLD_DEFAULT. This adds a proper implementation, which examines the address
of the calling function, and uses it to determine which library to use to begin
the symbol search process.
Change-Id: I2ad2b46363f68932af63a3828a22f9c7987eea67
dladdr() is a GNU extension function, which allows the caller to retrieve
symbol information for a specified memory address. It is useful for things
like generating backtrace information at runtime.
Change-Id: I3a1def1a6c9c666d93e1e97b7d260dfa5b9b79a9
Merge commit 'fe62de1ad036a1417df44b7b1a7c65cc79dc7091' into eclair-plus-aosp
* commit 'fe62de1ad036a1417df44b7b1a7c65cc79dc7091':
Add support for R_ARM_REL32 to the dynamic linker.
Changed it so that when the linker generates error messages, they are
scribbled away into a buffer that dlfcn and friends can read from.
Since the error messages are generetad with snprintf, and snprintf
MAY call malloc during some code paths, we now link against a version
of libc that does not contain malloc/free/realloc/calloc. We then define
malloc and friends in the dynamic loader, and make them abort() if they
are ever called.
Signed-off-by: Dima Zavin <dima@android.com>
