It combines updating r_state with the debugger notification.
The second change to _dl_open introduces an additional debugger
notification for dlmopen, but debuggers are expected to ignore it.
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
On 32-bit architecture ubsan triggers:
UBSAN: Undefined behaviour in dl-load.c:1345:54 pointer index expression with base 0x00612508 overflowed to 0xf7c3a508
Use explicit uintptr_t operation instead.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
The BZ 32653 fix (12a497c716) kept the
stack pointer zeroing from make_main_stack_executable on
_dl_make_stack_executable. However, previously the 'stack_endp'
pointed to temporary variable created before the call of
_dl_map_object_from_fd; while now we use the __libc_stack_end
directly.
Since pthread_getattr_np relies on correct __libc_stack_end, if
_dl_make_stack_executable is called (for instance, when
glibc.rtld.execstack=2 is set) __libc_stack_end will be set to zero,
and the call will always fail.
The __libc_stack_end zero was used a mitigation hardening, but since
52a01100ad it is used solely on
pthread_getattr_np code. So there is no point in zeroing anymore.
Checked on x86_64-linux-gnu and i686-linux-gnu.
Reviewed-by: Sam James <sam@gentoo.org>
When an executable is invoked directly, we calculate $ORIGIN by calling
readlink on /proc/self/exe, which the Linux kernel resolves to the
target of any symlinks. However, if an executable is run through ld.so,
we cannot use /proc/self/exe and instead use the path given as an
argument. This leads to a different calculation of $ORIGIN, which is
most notable in that it causes ldd to behave differently (e.g., by not
finding a library) from directly running the program.
To make the behavior consistent, take advantage of the fact that the
kernel also resolves /proc/self/fd/ symlinks to the target of any
symlinks in the same manner, so once we have opened the main executable
in order to load it, replace the user-provided path with the result of
calling readlink("/proc/self/fd/N").
(On non-Linux platforms this resolution does not happen and so no
behavior change is needed.)
The __fd_to_filename requires _fitoa_word and _itoa_word, which for
32-bits pulls a lot of definitions from _itoa.c (due _ITOA_NEEDED
being defined). To simplify the build move the required function
to a new file, _fitoa_word.c.
Checked on x86_64-linux-gnu and i686-linux-gnu.
Co-authored-by: Geoffrey Thomas <geofft@ldpreload.com>
Reviewed-by: Geoffrey Thomas <geofft@ldpreload.com>
Tested-by: Geoffrey Thomas <geofft@ldpreload.com>
It's not necessary to introduce temporaries because the compiler
is able to evaluate l_soname just once in constracts like:
l_soname (l) != NULL && strcmp (l_soname (l), LIBC_SO) != 0
The new tunable can be used to control whether executable stacks are
allowed from either the main program or dependencies. The default is
to allow executable stacks.
The executable stacks default permission is checked agains the one
provided by the PT_GNU_STACK from program headers (if present). The
tunable also disables the stack permission change if any dependency
requires an executable stack at loading time.
Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
If some shared library loaded with dlopen/dlmopen requires an executable
stack, either implicitly because of a missing GNU_STACK ELF header
(where the ABI default flags implies in the executable bit) or explicitly
because of the executable bit from GNU_STACK; the loader will try to set
the both the main thread and all thread stacks (from the pthread cache)
as executable.
Besides the issue where any __nptl_change_stack_perm failure does not
undo the previous executable transition (meaning that if the library
fails to load, there can be thread stacks with executable stacks), this
behavior was used on a CVE [1] as a vector for RCE.
This patch changes that if a shared library requires an executable
stack, and the current stack is not executable, dlopen fails. The
change is done only for dynamically loaded modules, if the program
or any dependency requires an executable stack, the loader will still
change the main thread before program execution and any thread created
with default stack configuration.
[1] https://www.qualys.com/2023/07/19/cve-2023-38408/rce-openssh-forwarded-ssh-agent.txt
Checked on x86_64-linux-gnu and i686-linux-gnu.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
Previously, the ld.so link map was silently added to the namespace.
This change produces an auditing event for it.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
This avoids immediate GLIBC_PRIVATE ABI issues if the size of
struct link_map or struct auditstate changes.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The declaration of found_other_class could be jumped
over via the goto just above it, but the code jumped
to uses found_other_class. Move the declaration
up a bit to ensure it's properly declared and initialized.
This case is detected early in the elf/dl-version.c consistency
checks. (These checks could be disabled in the future to allow
the removal of symbol versioning from objects.)
Commit f0b2132b35 ("ld.so: Support moving versioned symbols between
sonames [BZ #24741]) removed another call to _dl_name_match_p. The
_dl_check_caller function no longer exists, and the remaining calls
to _dl_name_match_p happen under the loader lock. This means that
atomic accesses are no longer required for the l_libname list. This
supersedes commit 395be7c218 ("elf: Fix data race in _dl_name_match_p
[BZ #21349]").
The __stack_prot is used by Linux to make the stack executable if
a modules requires it. It is also marked as RELRO, which requires
to change the segment permission to RW to update it.
Also, there is no need to keep track of the flags: either the stack
will have the default permission of the ABI or should be change to
PROT_READ | PROT_WRITE | PROT_EXEC. The only additional flag,
PROT_GROWSDOWN or PROT_GROWSUP, is Linux only and can be deducted
from _STACK_GROWS_DOWN/_STACK_GROWS_UP.
Also, the check_consistency function was already removed some time
ago.
Checked on x86_64-linux-gnu and i686-linux-gnu.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
The _dl_non_dynamic_init does not parse LD_PROFILE, which does not
enable profile for dlopen objects. Since dlopen is deprecated for
static objects, it is better to remove the support.
It also allows to trim down libc.a of profile support.
Checked on x86_64-linux-gnu.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
The open_path stops if a relative path in search path contains a
component that is a non directory (for instance, if the component
is an existing file).
For instance:
$ cat > lib.c <<EOF
> void foo (void) {}
> EOF
$ gcc -shared -fPIC -o lib.so lib.c
$ cat > main.c <<EOF
extern void foo ();
int main () { foo (); return 0; }
EOF
$ gcc -o main main.c lib.so
$ LD_LIBRARY_PATH=. ./main
$ LD_LIBRARY_PATH=non-existing/path:. ./main
$ LD_LIBRARY_PATH=$(pwd)/main:. ./main
$ LD_LIBRARY_PATH=./main:. ./main
./main: error while loading shared libraries: lib.so: cannot open shared object file: No such file or directory
The invalid './main' should be ignored as a non-existent one,
instead as a valid but non accessible file.
Absolute paths do not trigger this issue because their status are
initialized as 'unknown' and open_path check if this is a directory.
Checked on x86_64-linux-gnu.
Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
It is a left-over from commit 52a01100ad
("elf: Remove ad-hoc restrictions on dlopen callers [BZ #22787]").
When backporting commmit 6985865bc3
("elf: Always call destructors in reverse constructor order
(bug 30785)"), we can move the l_init_called_next field to this
place, so that the internal GLIBC_PRIVATE ABI does not change.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
Applying this commit results in bit-identical libc.so.6.
The elf/ld-linux-x86-64.so.2 does change, but only in .note.gnu.build-id
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
f55727ca53 updated open_path to use the
r_search_path_struct struct but failed to update the comment.
Signed-off-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
After commit ed3ce71f5c ("elf: Move la_activity (LA_ACT_ADD) after
_dl_add_to_namespace_list() (BZ #28062)") it is no longer necessary to
reset the debugger state in the error case, since the debugger
notification only happens after no more errors can occur.
The Z modifier is a nonstandard synonymn for z (that predates z
itself) and compiler might issue an warning for in invalid
conversion specifier.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
This reverts commit 6f85dbf102.
Once this change hits the release branches, it will require relinking
of all statically linked applications before static dlopen works
again, for the majority of updates on release branches: The NEWS file
is regularly updated with bug references, so the __libc_early_init
suffix changes, and static dlopen cannot find the function anymore.
While this ABI check is still technically correct (we do require
rebuilding & relinking after glibc updates to keep static dlopen
working), it is too drastic for stable release branches.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The files NEWS, include/link.h, and sysdeps/generic/ldsodefs.h
contribute to the version fingerprint used for detection. The
fingerprint can be further refined using the --with-extra-version-id
configure argument.
_dl_call_libc_early_init is replaced with _dl_lookup_libc_early_init.
The new function is used store a pointer to libc.so's
__libc_early_init function in the libc_map_early_init member of the
ld.so namespace structure. This function pointer can then be called
directly, so the separate invocation function is no longer needed.
The versioned symbol lookup needs the symbol versioning data
structures, so the initialization of libc_map and libc_map_early_init
is now done from _dl_check_map_versions, after this information
becomes available. (_dl_map_object_from_fd does not set this up
in time, so the initialization code had to be moved from there.)
This means that the separate initialization code can be removed from
dl_main because _dl_check_map_versions covers all maps, including
the initial executable loaded by the kernel. The lookup still happens
before relocation and the invocation of IFUNC resolvers, so IFUNC
resolvers are protected from ABI mismatch.
The __libc_early_init function pointer is not protected because
so little code runs between the pointer write and the invocation
(only dynamic linker code and IFUNC resolvers).
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
The kernel version check is used to avoid glibc to run on older
kernels where some syscall are not available and fallback code are
not enabled to handle graciously fail. However, it does not prevent
if the kernel does not correctly advertise its version through
vDSO note, uname or procfs.
Also kernel version checks are sometime not desirable by users,
where they want to deploy on different system with different kernel
version knowing the minimum set of syscall is always presented on
such systems.
The kernel version check has been removed along with the
LD_ASSUME_KERNEL environment variable. The minimum kernel used to
built glibc is still provided through NT_GNU_ABI_TAG ELF note and
also printed when libc.so is issued.
Checked on x86_64-linux-gnu.
On 32-bit machines this has no affect. On 64-bit machines
{u}int_fast{16|32} are set as {u}int64_t which is often not
ideal. Particularly x86_64 this change both saves code size and
may save instruction cost.
Full xcheck passes on x86_64.
Prelinked binaries and libraries still work, the dynamic tags
DT_GNU_PRELINKED, DT_GNU_LIBLIST, DT_GNU_CONFLICT just ignored
(meaning the process is reallocated as default).
The loader environment variable TRACE_PRELINKING is also removed,
since it used solely on prelink.
Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
Linker may set p_align of a PT_LOAD segment larger than p_align of the
first PT_LOAD segment to satisfy a section alignment:
Elf file type is DYN (Shared object file)
Entry point 0x0
There are 10 program headers, starting at offset 64
Program Headers:
Type Offset VirtAddr PhysAddr
FileSiz MemSiz Flags Align
LOAD 0x0000000000000000 0x0000000000000000 0x0000000000000000
0x0000000000000834 0x0000000000000834 R E 0x1000
LOAD 0x0000000000000e00 0x0000000000001e00 0x0000000000001e00
0x0000000000000230 0x0000000000000230 RW 0x1000
LOAD 0x0000000000400000 0x0000000000400000 0x0000000000400000
0x0000000000000004 0x0000000000000008 RW 0x400000
...
Section to Segment mapping:
Segment Sections...
00 .note.gnu.property .note.gnu.build-id .gnu.hash .dynsym .dynstr .gnu.version .gnu.version_r .rela.dyn .rela.plt .init .plt .plt.got .text .fini .rodata .eh_frame_hdr .eh_frame
01 .init_array .fini_array .data.rel.ro .dynamic .got .got.plt
02 .data .bss
We should align the first PT_LOAD segment to the maximum p_align of all
PT_LOAD segments, similar to the kernel commit:
commit ce81bb256a224259ab686742a6284930cbe4f1fa
Author: Chris Kennelly <ckennelly@google.com>
Date: Thu Oct 15 20:12:32 2020 -0700
fs/binfmt_elf: use PT_LOAD p_align values for suitable start address
This fixes BZ #28676.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
DT_RUNPATH is only used to find the immediate dependencies of the
executable or shared object containing the DT_RUNPATH entry. Update
LD_AUDIT dlopen call to try the DT_RUNPATH entry of the executable.
Add tst-audit14a, which is copied from tst-audit14, to DT_RUNPATH and
build tst-audit14 with -Wl,--disable-new-dtags to test DT_RPATH.
This partially fixes BZ #28455.
I used these shell commands:
../glibc/scripts/update-copyrights $PWD/../gnulib/build-aux/update-copyright
(cd ../glibc && git commit -am"[this commit message]")
and then ignored the output, which consisted lines saying "FOO: warning:
copyright statement not found" for each of 7061 files FOO.
I then removed trailing white space from math/tgmath.h,
support/tst-support-open-dev-null-range.c, and
sysdeps/x86_64/multiarch/strlen-vec.S, to work around the following
obscure pre-commit check failure diagnostics from Savannah. I don't
know why I run into these diagnostics whereas others evidently do not.
remote: *** 912-#endif
remote: *** 913:
remote: *** 914-
remote: *** error: lines with trailing whitespace found
...
remote: *** error: sysdeps/unix/sysv/linux/statx_cp.c: trailing lines
It consolidates the code required to call la_objsearch audit
callback.
Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
It consolidates the code required to call la_activity audit
callback.
Also for a new Lmid_t the namespace link_map list are empty, so it
requires to check if before using it. This can happen for when audit
module is used along with dlmopen.
Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
It consolidates the code required to call la_objopen audit callback.
Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
p_align does not have to be a multiple of the page size. Only PT_LOAD
segment layout should be aligned to the page size.
1: Remove p_align check against the page size.
2. Use the page size, instead of p_align, to check PT_LOAD segment layout.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
When PT_LOAD segment alignment > the page size, allocate enough space to
ensure that the segment can be properly aligned. This change helps code
segments use huge pages become simple and available.
This fixes [BZ #28676].
Signed-off-by: Xu Yu <xuyu@linux.alibaba.com>
Signed-off-by: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Separated debuginfo files have PT_DYNAMIC with p_filesz == 0. We
need to check for that before the _dl_map_segments call because
that could attempt to write to mappings that extend beyond the end
of the file, resulting in SIGBUS.
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
THe d6d89608ac broke powerpc for --enable-bind-now because it turned
out that different than patch assumption rtld elf_get_dynamic_info()
does require to handle RTLD_BOOTSTRAP to avoid DT_FLAGS and
DT_RUNPATH (more specially the GLRO usage which is not reallocate
yet).
This patch fixes by passing two arguments to elf_get_dynamic_info()
to inform that by rtld (bootstrap) or static pie initialization
(static_pie_bootstrap). I think using explicit argument is way more
clear and burried C preprocessor, and compiler should remove the
dead code.
I checked on x86_64 and i686 with default options, --enable-bind-now,
and --enable-bind-now and --enable--static-pie. I also check on
aarch64, armhf, powerpc64, and powerpc with default and
--enable-bind-now.
The 4af6982e4c fix does not fully handle RTLD_BOOTSTRAP usage on
rtld.c due two issues:
1. RTLD_BOOTSTRAP is also used on dl-machine.h on various
architectures and it changes the semantics of various machine
relocation functions.
2. The elf_get_dynamic_info() change was done sideways, previously
to 490e6c62aa get-dynamic-info.h was included by the first
dynamic-link.h include *without* RTLD_BOOTSTRAP being defined.
It means that the code within elf_get_dynamic_info() that uses
RTLD_BOOTSTRAP is in fact unused.
To fix 1. this patch now includes dynamic-link.h only once with
RTLD_BOOTSTRAP defined. The ELF_DYNAMIC_RELOCATE call will now have
the relocation fnctions with the expected semantics for the loader.
And to fix 2. part of 4af6982e4c is reverted (the check argument
elf_get_dynamic_info() is not required) and the RTLD_BOOTSTRAP
pieces are removed.
To reorganize the includes the static TLS definition is moved to
its own header to avoid a circular dependency (it is defined on
dynamic-link.h and dl-machine.h requires it at same time other
dynamic-link.h definition requires dl-machine.h defitions).
Also ELF_MACHINE_NO_REL, ELF_MACHINE_NO_RELA, and ELF_MACHINE_PLT_REL
are moved to its own header. Only ancient ABIs need special values
(arm, i386, and mips), so a generic one is used as default.
The powerpc Elf64_FuncDesc is also moved to its own header, since
csu code required its definition (which would require either include
elf/ folder or add a full path with elf/).
Checked on x86_64, i686, aarch64, armhf, powerpc64, powerpc32,
and powerpc64le.
Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
Before to 490e6c62aa ('elf: Avoid nested functions in the loader
[BZ #27220]'), elf_get_dynamic_info() was defined twice on rtld.c: on
the first dynamic-link.h include and later within _dl_start(). The
former definition did not define DONT_USE_BOOTSTRAP_MAP and it is used
on setup_vdso() (since it is a global definition), while the former does
define DONT_USE_BOOTSTRAP_MAP and it is used on loader self-relocation.
With the commit change, the function is now included and defined once
instead of defined as a nested function. So rtld.c defines without
defining RTLD_BOOTSTRAP and it brokes at least powerpc32.
This patch fixes by moving the get-dynamic-info.h include out of
dynamic-link.h, which then the caller can corirectly set the expected
semantic by defining STATIC_PIE_BOOTSTRAP, RTLD_BOOTSTRAP, and/or
RESOLVE_MAP.
It also required to enable some asserts only for the loader bootstrap
to avoid issues when called from setup_vdso().
As a side note, this is another issues with nested functions: it is
not clear from pre-processed output (-E -dD) how the function will
be build and its semantic (since nested function will be local and
extra C defines may change it).
I checked on x86_64-linux-gnu (w/o --enable-static-pie),
i686-linux-gnu, powerpc64-linux-gnu, powerpc-linux-gnu-power4,
aarch64-linux-gnu, arm-linux-gnu, sparc64-linux-gnu, and
s390x-linux-gnu.
Reviewed-by: Fangrui Song <maskray@google.com>
When add ld.so to a new namespace, we don't actually load ld.so. We
create a new link map and refers the real one for almost everything.
Copy l_addr and l_ld from the real ld.so link map to avoid GDB warning:
warning: .dynamic section for ".../elf/ld-linux-x86-64.so.2" is not at the expected address (wrong library or version mismatch?)
when handling shared library loaded by dlmopen.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
We can't relocate entries in dynamic section if it is readonly:
1. Add a l_ld_readonly field to struct link_map to indicate if dynamic
section is readonly and set it based on p_flags of PT_DYNAMIC segment.
2. Replace DL_RO_DYN_SECTION with dl_relocate_ld to decide if dynamic
section should be relocated.
3. Remove DL_RO_DYN_TEMP_CNT.
4. Don't use a static dynamic section to make readonly dynamic section
in vDSO writable.
5. Remove the temp argument from elf_get_dynamic_info.
This fixes BZ #28340.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
Glibc does not provide an interface for debugger to access libraries
loaded in multiple namespaces via dlmopen.
The current rtld-debugger interface is described in the file:
elf/rtld-debugger-interface.txt
under the "Standard debugger interface" heading. This interface only
provides access to the first link-map (LM_ID_BASE).
1. Bump r_version to 2 when multiple namespaces are used. This triggers
the GDB bug:
https://sourceware.org/bugzilla/show_bug.cgi?id=28236
2. Add struct r_debug_extended to extend struct r_debug into a linked-list,
where each element correlates to an unique namespace.
3. Initialize the r_debug_extended structure. Bump r_version to 2 for
the new namespace and add the new namespace to the namespace linked list.
4. Add _dl_debug_update to return the address of struct r_debug' of a
namespace.
5. Add a hidden symbol, _r_debug_extended, for struct r_debug_extended.
6. Provide the symbol, _r_debug, with size of struct r_debug, as an alias
of _r_debug_extended, for programs which reference _r_debug.
This fixes BZ #15971.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
