Add MemoryMap::Iterator to support different strategies for locating
the start of module mappings on Android and Linux.
Beginning with API 21, Bionic provides android_dlopen_ext() which
allows passing a file descriptor with an existing relro segment to the
loader. This means that the mapping containing the dynamic segment
could have a name, device, and inode which are different than the
other mappings for the module.
The revised strategy for Android at API 21+ is to search all mappings
in reverse order from they dynamic array mapping until a module is
parsed with the expected dynamic array address.
Linux and Android 20- continue to select mappings using the device,
inode, and file offsets of the mappings.
Bug: crashpad:268
Change-Id: I30e95e51cb6874c00875d2a9c57f1249877736d4
Reviewed-on: https://chromium-review.googlesource.com/c/1374375
Commit-Queue: Joshua Peraza <jperaza@chromium.org>
Reviewed-by: Mark Mentovai <mark@chromium.org>
Modules mapped from zipfiles will have mappings named for the zipfile
rather than the module name and an offset into that zipfile instead of
0.
Bug: crashpad:253, crashpad:254
Change-Id: I0503d13e7b80ba7bd1cc2d241633d9c68c98f1cd
Reviewed-on: https://chromium-review.googlesource.com/1232294
Reviewed-by: Mark Mentovai <mark@chromium.org>
The general strategy used by Crashpad to determine loaded modules is to
read the link_map to get the addresses of the dynamic arrays for all
loaded modules. Those addresses can then be used to query the MemoryMap
to locate the module's mappings, and in particular the base mapping
from which Crashpad can parse the entire loaded ELF file.
ELF modules are typically loaded in several mappings with varying
permissions for different segments. The previous strategy used to find
the base mapping for a module was to search backwards from the mapping
for the dynamic array until a mapping from file offset 0 was found for
the same file. This fails when the file is mapped multiple times from
file offset 0, which can happen if the first page of the file contains
a GNU_RELRO segment.
This new strategy queries the MemoryMap for ALL mappings associated
with the dynamic array's mapping, mapped from offset 0. The consumer
(process_reader_linux.cc) can then determine which mapping is the
correct base by attempting to parse a module at that address and
corroborating the PT_DYNAMIC or program header table address from the
parsed module with the values Crashpad gets from the link_map or
auxiliary vector.
Bug: crashpad:30
Change-Id: Ibfcbba512e8fccc8c65afef734ea5640b71e9f70
Reviewed-on: https://chromium-review.googlesource.com/1139396
Commit-Queue: Joshua Peraza <jperaza@chromium.org>
Reviewed-by: Mark Mentovai <mark@chromium.org>
Some files, such as /proc/[pid]/maps, may not be accessible to the
handler. This enables the handler access to the contents of those files
via the broker.
This change reads maps and auxv using ReadFileContents.
Bug: crashpad:30
Change-Id: Ia19b498bae473c616ea794ab51c3f22afd5795be
Reviewed-on: https://chromium-review.googlesource.com/989406
Reviewed-by: Mark Mentovai <mark@chromium.org>
ELF executables and libraries may be loaded into memory in several
mappings, possibly with holes containing anonymous mappings
or mappings of other files. This method takes an input mapping and
attempts to find the mapping for file offset 0 of the same file.
Bug: crashpad:30
Change-Id: I79abf060b015d58ef0eba54a399a74315d7d2d77
Reviewed-on: https://chromium-review.googlesource.com/565223
Commit-Queue: Joshua Peraza <jperaza@chromium.org>
Reviewed-by: Mark Mentovai <mark@chromium.org>
