This was only used by HashTable::dump() which I used when doing the
first HashTable implementation. Removing this allows us to also remove
most includes of <AK/kstdio.h>.
As suggested by Joshua, this commit adds the 2-clause BSD license as a
comment block to the top of every source file.
For the first pass, I've just added myself for simplicity. I encourage
everyone to add themselves as copyright holders of any file they've
added or modified in some significant way. If I've added myself in
error somewhere, feel free to replace it with the appropriate copyright
holder instead.
Going forward, all new source files should include a license header.
It was possible to craft a custom ELF executable that when symbolicated
would cause the kernel to read from user-controlled addresses anywhere
in memory. You could then fetch this memory via /proc/PID/stack
We fix this by making ELFImage hand out StringView rather than raw
const char* for symbol names. In case a symbol offset is outside the
ELF image, you get a null StringView. :^)
Test: Kernel/elf-symbolication-kernel-read-exploit.cpp
These will make sure there's no funny business or funny offsets in the
main ELF header or each Program Header. More can still be done (like
validating section headers), but this is a good start
Since ELFDynamicObject needs the actual virtual address of the .dynamic
section in the loaded image, and not the file offset like we assumed
before, due to MAP_PRIVATE secretly giving us a MAP_SHARED, we can
remove all of the Dynamic* code from ELFImage.
ELFDynamicLoader only needs ELFImage to get the Program headers at this
point. More consolidation opportunities seem likely in the future.
Before this, you could make the kernel copy memory from anywhere by
setting up an ELF executable with a program header specifying file
offsets outside the file.
Since ELFImage didn't even know how large it was, we had no clue that
we were copying things from outside the ELF.
Fix this by adding a size field to ELFImage and validating program
header ranges before memcpy()'ing to them.
The ELF code is definitely going to need more validation and checking.
Separate some responsibilities:
ELFDynamicLoader is responsible for loading elf binaries from disk and
performing relocations, calling init functions, and eventually calling
finalizer functions.
ELFDynamicObject is a helper class to parse the .dynamic section of an
elf binary, or the table of Elf32_Dyn entries at the _DYNAMIC symbol.
ELFDynamicObject now owns the helper classes for Relocations, Symbols,
Sections and the like that ELFDynamicLoader will use to perform
relocations and symbol lookup.
Because these new helpers are constructed from offsets into the .dynamic
section within the loaded .data section of the binary, we don't need the
ELFImage for nearly as much of the loading processes as we did before.
Therefore we can remove most of the extra DynamicXXX classes and just
keep the one that lets us find the location of _DYNAMIC in the new ELF.
And finally, since we changed the name of the class that dlopen/dlsym
care about, we need to compile/link and use the new ELFDynamicLoader
class in LibC.
This patch also adds some missing relocation defines to exec_elf.h,
and a few helper classes/methods to ELFImage so that we can use it
for our dynamically loaded libs and not just main program images from
the kernel :)
