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* rtld: Remove DL_ARGV_NOT_RELRO and make _dl_skip_args constSzabolcs Nagy2022-05-051-8/+2
| | | | | | | | | | | | | | | | _dl_skip_args is always 0, so the target specific code that modifies argv after relro protection is applied is no longer used. After the patch relro protection is applied to _dl_argv consistently on all targets. --- v6: - const _dl_skip_args. v4: - New patch. Reviewed-by: Florian Weimer <fweimer@redhat.com> Tested-by: Florian Weimer <fweimer@redhat.com>
* rtld: Use generic argv adjustment in ld.so [BZ #23293]Szabolcs Nagy2022-05-051-13/+60
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When an executable is invoked as ./ld.so [ld.so-args] ./exe [exe-args] then the argv is adujusted in ld.so before calling the entry point of the executable so ld.so args are not visible to it. On most targets this requires moving argv, env and auxv on the stack to ensure correct stack alignment at the entry point. This had several issues: - The code for this adjustment on the stack is written in asm as part of the target specific ld.so _start code which is hard to maintain. - The adjustment is done after _dl_start returns, where it's too late to update GLRO(dl_auxv), as it is already readonly, so it points to memory that was clobbered by the adjustment. This is bug 23293. - _environ is also wrong in ld.so after the adjustment, but it is likely not used after _dl_start returns so this is not user visible. - _dl_argv was updated, but for this it was moved out of relro, which changes security properties across targets unnecessarily. This patch introduces a generic _dl_start_args_adjust function that handles the argument adjustments after ld.so processed its own args and before relro protection is applied. The same algorithm is used on all targets, _dl_skip_args is now 0, so existing target specific adjustment code is no longer used. The bug affects aarch64, alpha, arc, arm, csky, ia64, nios2, s390-32 and sparc, other targets don't need the change in principle, only for consistency. The GNU Hurd start code relied on _dl_skip_args after dl_main returned, now it checks directly if args were adjusted and fixes the Hurd startup data accordingly. Follow up patches can remove _dl_skip_args and DL_ARGV_NOT_RELRO. Tested on aarch64-linux-gnu and cross tested on i686-gnu. --- v6: - don't pass start_argptr to _dl_main, just use _dl_argv-1. - add comment for _dl_start_args_adjust. - add assert checks to _dl_start_args_adjust and simplify it a bit. v5: - Hurd specific changes. v4: - New code is unconditionally used on all targets. - Hide auxv adjustments behind HAVE_AUX_VECTOR. - DL_NEED_START_ARGS_ADJUST macro is removed. - _dl_skip_args is no longer unused. - start_argptr is passed down to dl_main instead of using a global. - moved aarch64 DL_ARGV_NOT_RELRO removal to separate patch. v2: - use p != NULL, and a_type != AT_NULL - remove the confusing paragraph from the commit message.
* Use __ehdr_start rather than _begin in _dl_start_finalAlan Modra2022-04-281-4/+3
| | | | | | | | | | __ehdr_start is already used in rltld.c:dl_main, and can serve the same purpose as _begin. Besides tidying the code, using linker defined section relative symbols rather than "-defsym _begin=0" better reflects the intent of _dl_start_final use of _begin, which is to refer to the load address of ld.so rather than absolute address zero. Reviewed-by: Florian Weimer <fweimer@redhat.com>
* elf: Replace PI_STATIC_AND_HIDDEN with opposite HIDDEN_VAR_NEEDS_DYNAMIC_RELOCFangrui Song2022-04-261-1/+1
| | | | | | | | | | | | | | | | | | PI_STATIC_AND_HIDDEN indicates whether accesses to internal linkage variables and hidden visibility variables in a shared object (ld.so) need dynamic relocations (usually R_*_RELATIVE). PI (position independent) in the macro name is a misnomer: a code sequence using GOT is typically position-independent as well, but using dynamic relocations does not meet the requirement. Not defining PI_STATIC_AND_HIDDEN is legacy and we expect that all new ports will define PI_STATIC_AND_HIDDEN. Current ports defining PI_STATIC_AND_HIDDEN are more than the opposite. Change the configure default. No functional change. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* elf: Move post-relocation code of _dl_start into _dl_start_finalFangrui Song2022-04-251-15/+10
| | | | | | | | | | | | | | | | On non-PI_STATIC_AND_HIDDEN architectures, getting the address of _rtld_local_ro (for GLRO (dl_final_object)) goes through a GOT entry. The GOT load may be reordered before self relocation, leading to an unrelocated/incorrect _rtld_local_ro address. 84e02af1ebc9988126eebe60bf19226cea835623 tickled GCC powerpc32 to reorder the GOT load before relative relocations, leading to ld.so crash. This is similar to the m68k jump table reordering issue fixed by a8e9b5b8079d18116ca69c9797e77804ecf2ee7e. Move code after self relocation into _dl_start_final to avoid the reordering. This fixes powerpc32 and may help other architectures when ELF_DYNAMIC_RELOCATE is simplified in the future.
* elf: Remove LD_USE_LOAD_BIASAdhemerval Zanella2022-02-101-13/+0
| | | | | | | | It is solely for prelink with PIE executables [1]. [1] https://sourceware.org/legacy-ml/libc-hacker/2003-11/msg00127.html Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
* malloc: Remove LD_TRACE_PRELINKING usage from mtraceAdhemerval Zanella2022-02-101-9/+13
| | | | | | | | | | | | | | | | | | | | | | The fix for BZ#22716 replacde LD_TRACE_LOADED_OBJECTS with LD_TRACE_PRELINKING so mtrace could record executable address position. To provide the same information, LD_TRACE_LOADED_OBJECTS is extended where a value or '2' also prints the executable address as well. It avoid adding another loader environment variable to be used solely for mtrace. The vDSO will be printed as a default library (with '=>' pointing the same name), which is ok since both mtrace and ldd already handles it. The mtrace script is changed to also parse the new format. To correctly support PIE and non-PIE executables, both the default mtrace address and the one calculated as used (it fixes mtrace for non-PIE exectuable as for BZ#22716 for PIE). Checked on x86_64-linux-gnu. Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
* elf: Remove prelink supportAdhemerval Zanella2022-02-101-200/+50
| | | | | | | | | | | | | 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>
* elf: Fix runtime linker auditing on aarch64 (BZ #26643)Ben Woodard2022-02-011-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The rtld audit support show two problems on aarch64: 1. _dl_runtime_resolve does not preserve x8, the indirect result location register, which might generate wrong result calls depending of the function signature. 2. The NEON Q registers pushed onto the stack by _dl_runtime_resolve were twice the size of D registers extracted from the stack frame by _dl_runtime_profile. While 2. might result in wrong information passed on the PLT tracing, 1. generates wrong runtime behaviour. The aarch64 rtld audit support is changed to: * Both La_aarch64_regs and La_aarch64_retval are expanded to include both x8 and the full sized NEON V registers, as defined by the ABI. * dl_runtime_profile needed to extract registers saved by _dl_runtime_resolve and put them into the new correctly sized La_aarch64_regs structure. * The LAV_CURRENT check is change to only accept new audit modules to avoid the undefined behavior of not save/restore x8. * Different than other architectures, audit modules older than LAV_CURRENT are rejected (both La_aarch64_regs and La_aarch64_retval changed their layout and there are no requirements to support multiple audit interface with the inherent aarch64 issues). * A new field is also reserved on both La_aarch64_regs and La_aarch64_retval to support variant pcs symbols. Similar to x86, a new La_aarch64_vector type to represent the NEON register is added on the La_aarch64_regs (so each type can be accessed directly). Since LAV_CURRENT was already bumped to support bind-now, there is no need to increase it again. Checked on aarch64-linux-gnu. Co-authored-by: Adhemerval Zanella <adhemerval.zanella@linaro.org> Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com> Reviewed-by: Carlos O'Donell <carlos@redhat.com> Tested-by: Carlos O'Donell <carlos@redhat.com>
* elf: Fix initial-exec TLS access on audit modules (BZ #28096)Adhemerval Zanella2022-02-011-1/+1
| | | | | | | | | | | | | | | | | For audit modules and dependencies with initial-exec TLS, we can not set the initial TLS image on default loader initialization because it would already be set by the audit setup. However, subsequent thread creation would need to follow the default behaviour. This patch fixes it by setting l_auditing link_map field not only for the audit modules, but also for all its dependencies. This is used on _dl_allocate_tls_init to avoid the static TLS initialization at load time. Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu. Reviewed-by: Carlos O'Donell <carlos@redhat.com> Tested-by: Carlos O'Donell <carlos@redhat.com>
* elf: Set l_contiguous to 1 for the main map in more casesFlorian Weimer2022-01-171-0/+25
| | | | | | | | | | | | | | | | | l_contiguous was not initialized at all for the main map and always 0. This commit adds code to check if the LOAD segments are adjacent to each other, and sets l_contiguous accordingly. This helps _dl_find_object because it is more efficient if the main mapping is contiguous. Note that not all (PIE or non-PIE) binaries are contiguous in this way because BFD ld creates executables with LOAD holes: ELF LOAD segments creating holes in the process image on GNU/Linux https://sourceware.org/pipermail/binutils/2022-January/119082.html https://sourceware.org/bugzilla/show_bug.cgi?id=28743 Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
* elf: Introduce rtld_setup_main_mapFlorian Weimer2022-01-171-144/+159
| | | | | | | This function collects most of the processing needed to initialize the link map for the main executable. Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
* elf: Add <dl-debug.h>H.J. Lu2022-01-031-9/+4
| | | | | | | Add <dl-debug.h> to setup debugging entry in PT_DYNAMIC segment to support DT_DEBUG, DT_MIPS_RLD_MAP_REL and DT_MIPS_RLD_MAP. Tested on x86-64, x32 and i686 as well as with build-many-glibcs.py.
* Update copyright dates with scripts/update-copyrightsPaul Eggert2022-01-011-1/+1
| | | | | | | | | | | | | | | | | | | | | | | 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
* elf: Add _dl_find_object functionFlorian Weimer2021-12-281-0/+11
| | | | | | | | | | | | | | | | | | | | | | | | | It can be used to speed up the libgcc unwinder, and the internal _dl_find_dso_for_object function (which is used for caller identification in dlopen and related functions, and in dladdr). _dl_find_object is in the internal namespace due to bug 28503. If libgcc switches to _dl_find_object, this namespace issue will be fixed. It is located in libc for two reasons: it is necessary to forward the call to the static libc after static dlopen, and there is a link ordering issue with -static-libgcc and libgcc_eh.a because libc.so is not a linker script that includes ld.so in the glibc build tree (so that GCC's internal -lc after libgcc_eh.a does not pick up ld.so). It is necessary to do the i386 customization in the sysdeps/x86/bits/dl_find_object.h header shared with x86-64 because otherwise, multilib installations are broken. The implementation uses software transactional memory, as suggested by Torvald Riegel. Two copies of the supporting data structures are used, also achieving full async-signal-safety. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* elf: Issue audit la_objopen for vDSOAdhemerval Zanella2021-12-281-0/+6
| | | | | | | | | | | | | | | The vDSO is is listed in the link_map chain, but is never the subject of an la_objopen call. A new internal flag __RTLD_VDSO is added that acts as __RTLD_OPENEXEC to allocate the required 'struct auditstate' extra space for the 'struct link_map'. The return value from the callback is currently ignored, since there is no PLT call involved by glibc when using the vDSO, neither the vDSO are exported directly. Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu. Reviewed-by: Florian Weimer <fweimer@redhat.com>
* elf: Avoid unnecessary slowdown from profiling with audit (BZ#15533)Adhemerval Zanella2021-12-281-7/+1
| | | | | | | | | | | | | | | | | | | The rtld-audit interfaces introduces a slowdown due to enabling profiling instrumentation (as if LD_AUDIT implied LD_PROFILE). However, instrumenting is only necessary if one of audit libraries provides PLT callbacks (la_pltenter or la_pltexit symbols). Otherwise, the slowdown can be avoided. The following patch adjusts the logic that enables profiling to iterate over all audit modules and check if any of those provides a PLT hook. To keep la_symbind to work even without PLT callbacks, _dl_fixup now calls the audit callback if the modules implements it. Co-authored-by: Alexander Monakov <amonakov@ispras.ru> Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu. Reviewed-by: Florian Weimer <fweimer@redhat.com>
* elf: Add _dl_audit_activity_map and _dl_audit_activity_nsidAdhemerval Zanella2021-12-281-29/+2
| | | | | | | | | | | | | 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>
* elf: Add _dl_audit_objopenAdhemerval Zanella2021-12-281-21/+2
| | | | | | | | 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>
* elf: Use errcode instead of (unset) errno in rtld_chain_loadFlorian Weimer2021-12-101-1/+1
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* elf: execve statically linked programs instead of crashing [BZ #28648]Florian Weimer2021-12-051-8/+42
| | | | | | | | | | | | | | | Programs without dynamic dependencies and without a program interpreter are now run via execve. Previously, the dynamic linker either crashed while attempting to read a non-existing dynamic segment (looking for DT_AUDIT/DT_DEPAUDIT data), or the self-relocated in the static PIE executable crashed because the outer dynamic linker had already applied RELRO protection. <dl-execve.h> is needed because execve is not available in the dynamic loader on Hurd. Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
* elf: Introduce GLRO (dl_libc_freeres), called from __libc_freeresFlorian Weimer2021-11-171-0/+1
| | | | | | | This will be used to deallocate memory allocated using the non-minimal malloc. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* elf: Fix slow DSO sorting behavior in dynamic loader (BZ #17645)Chung-Lin Tang2021-10-211-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This second patch contains the actual implementation of a new sorting algorithm for shared objects in the dynamic loader, which solves the slow behavior that the current "old" algorithm falls into when the DSO set contains circular dependencies. The new algorithm implemented here is simply depth-first search (DFS) to obtain the Reverse-Post Order (RPO) sequence, a topological sort. A new l_visited:1 bitfield is added to struct link_map to more elegantly facilitate such a search. The DFS algorithm is applied to the input maps[nmap-1] backwards towards maps[0]. This has the effect of a more "shallow" recursion depth in general since the input is in BFS. Also, when combined with the natural order of processing l_initfini[] at each node, this creates a resulting output sorting closer to the intuitive "left-to-right" order in most cases. Another notable implementation adjustment related to this _dl_sort_maps change is the removing of two char arrays 'used' and 'done' in _dl_close_worker to represent two per-map attributes. This has been changed to simply use two new bit-fields l_map_used:1, l_map_done:1 added to struct link_map. This also allows discarding the clunky 'used' array sorting that _dl_sort_maps had to sometimes do along the way. Tunable support for switching between different sorting algorithms at runtime is also added. A new tunable 'glibc.rtld.dynamic_sort' with current valid values 1 (old algorithm) and 2 (new DFS algorithm) has been added. At time of commit of this patch, the default setting is 1 (old algorithm). Signed-off-by: Chung-Lin Tang <cltang@codesourcery.com> Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* ld.so: Initialize bootstrap_map.l_ld_readonly [BZ #28340]H.J. Lu2021-10-191-0/+1
| | | | | | | | | | | | | | | 1. Define DL_RO_DYN_SECTION to initalize bootstrap_map.l_ld_readonly before calling elf_get_dynamic_info to get dynamic info in bootstrap_map, 2. Define a single static inline bool dl_relocate_ld (const struct link_map *l) { /* Don't relocate dynamic section if it is readonly */ return !(l->l_ld_readonly || DL_RO_DYN_SECTION); } This updates BZ #28340 fix.
* elf: Fix elf_get_dynamic_info() for bootstrapAdhemerval Zanella2021-10-181-2/+2
| | | | | | | | | | | | | | | | | | | THe d6d89608ac8c 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.
* elf: Fix dynamic-link.h usage on rtld.cAdhemerval Zanella2021-10-141-12/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* elf: Fix elf_get_dynamic_info definitionAdhemerval Zanella2021-10-121-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Before to 490e6c62aa31a8a ('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>
* elf: Avoid nested functions in the loader [BZ #27220]Fangrui Song2021-10-071-8/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | dynamic-link.h is included more than once in some elf/ files (rtld.c, dl-conflict.c, dl-reloc.c, dl-reloc-static-pie.c) and uses GCC nested functions. This harms readability and the nested functions usage is the biggest obstacle prevents Clang build (Clang doesn't support GCC nested functions). The key idea for unnesting is to add extra parameters (struct link_map *and struct r_scope_elm *[]) to RESOLVE_MAP, ELF_MACHINE_BEFORE_RTLD_RELOC, ELF_DYNAMIC_RELOCATE, elf_machine_rel[a], elf_machine_lazy_rel, and elf_machine_runtime_setup. (This is inspired by Stan Shebs' ppc64/x86-64 implementation in the google/grte/v5-2.27/master which uses mixed extra parameters and static variables.) Future simplification: * If mips elf_machine_runtime_setup no longer needs RESOLVE_GOTSYM, elf_machine_runtime_setup can drop the `scope` parameter. * If TLSDESC no longer need to be in elf_machine_lazy_rel, elf_machine_lazy_rel can drop the `scope` parameter. Tested on aarch64, i386, x86-64, powerpc64le, powerpc64, powerpc32, sparc64, sparcv9, s390x, s390, hppa, ia64, armhf, alpha, and mips64. In addition, tested build-many-glibcs.py with {arc,csky,microblaze,nios2}-linux-gnu and riscv64-linux-gnu-rv64imafdc-lp64d. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* ld.so: Don't fill the DT_DEBUG entry in ld.so [BZ #28129]H.J. Lu2021-10-061-6/+0
| | | | | | Linker creates the DT_DEBUG entry only in executables. Don't fill the non-existent DT_DEBUG entry in ld.so with the run-time address of the r_debug structure. This fixes BZ #28129.
* elf: Avoid deadlock between pthread_create and ctors [BZ #28357]Szabolcs Nagy2021-10-041-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | The fix for bug 19329 caused a regression such that pthread_create can deadlock when concurrent ctors from dlopen are waiting for it to finish. Use a new GL(dl_load_tls_lock) in pthread_create that is not taken around ctors in dlopen. The new lock is also used in __tls_get_addr instead of GL(dl_load_lock). The new lock is held in _dl_open_worker and _dl_close_worker around most of the logic before/after the init/fini routines. When init/fini routines are running then TLS is in a consistent, usable state. In _dl_open_worker the new lock requires catching and reraising dlopen failures that happen in the critical section. The new lock is reinitialized in a fork child, to keep the existing behaviour and it is kept recursive in case malloc interposition or TLS access from signal handlers can retake it. It is not obvious if this is necessary or helps, but avoids changing the preexisting behaviour. The new lock may be more appropriate for dl_iterate_phdr too than GL(dl_load_write_lock), since TLS state of an incompletely loaded module may be accessed. If the new lock can replace the old one, that can be a separate change. Fixes bug 28357. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* ld.so: Replace DL_RO_DYN_SECTION with dl_relocate_ld [BZ #28340]H.J. Lu2021-09-221-2/+4
| | | | | | | | | | | | | | | | | 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>
* Extend struct r_debug to support multiple namespaces [BZ #15971]H.J. Lu2021-09-191-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* elf: Unconditionally use __ehdr_startFangrui Song2021-08-101-9/+4
| | | | | | | | | | | | | We can consider __ehdr_start (from binutils 2.23 onwards) unconditionally supported, since configure.ac requires binutils>=2.25. The configure.ac check is related to an ia64 bug fixed by binutils 2.24. See https://sourceware.org/pipermail/libc-alpha/2014-August/053503.html Tested on x86_64-linux-gnu. Tested build-many-glibcs.py with aarch64-linux-gnu and s390x-linux-gnu. Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
* elf: Fix DTV gap reuse logic (BZ #27135)Adhemerval Zanella2021-07-141-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | This is updated version of the 572bd547d57a (reverted by 40ebfd016ad2) that fixes the _dl_next_tls_modid issues. This issue with 572bd547d57a patch is the DTV entry will be only update on dl_open_worker() with the update_tls_slotinfo() call after all dependencies are being processed by _dl_map_object_deps(). However _dl_map_object_deps() itself might call _dl_next_tls_modid(), and since the _dl_tls_dtv_slotinfo_list::map is not yet set the entry will be wrongly reused. This patch fixes by renaming the _dl_next_tls_modid() function to _dl_assign_tls_modid() and by passing the link_map so it can set the slotinfo value so a subsequente _dl_next_tls_modid() call will see the entry as allocated. The intermediary value is cleared up on remove_slotinfo() for the case a library fails to load with RTLD_NOW. This patch fixes BZ #27135. Checked on x86_64-linux-gnu. Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
* Force building with -fno-commonFlorian Weimer2021-07-091-2/+1
| | | | | | | | | | As a result, is not necessary to specify __attribute__ ((nocommon)) on individual definitions. GCC 10 defaults to -fno-common on all architectures except ARC, but this change is compatible with older GCC versions and ARC, too. Reviewed-by: Carlos O'Donell <carlos@redhat.com>
* nptl: Move changing of stack permissions into ld.soFlorian Weimer2021-05-101-0/+2
| | | | | | | | | All the stack lists are now in _rtld_global, so it is possible to change stack permissions directly from there, instead of calling into libpthread to do the change. Tested-by: Carlos O'Donell <carlos@redhat.com> Reviewed-by: Carlos O'Donell <carlos@redhat.com>
* elf: Introduce __tls_pre_init_tpFlorian Weimer2021-05-101-37/+1
| | | | | | | | | | | This is an early variant of __tls_init_tp, primarily for initializing thread-related elements of _rtld_global/GL. Some existing initialization code not needed for NPTL is moved into the generic version of this function. Tested-by: Carlos O'Donell <carlos@redhat.com> Reviewed-by: Carlos O'Donell <carlos@redhat.com>
* elf, nptl: Resolve recursive lock implementation earlyFlorian Weimer2021-05-101-0/+18
| | | | | | | | | | | If libpthread is included in libc, it is not necessary to delay initialization of the lock/unlock function pointers until libpthread is loaded. This eliminates two unprotected function pointers from _rtld_global and removes some initialization code from libpthread. Tested-by: Carlos O'Donell <carlos@redhat.com> Reviewed-by: Carlos O'Donell <carlos@redhat.com>
* elf, nptl: Initialize static TLS directly in ld.soFlorian Weimer2021-05-051-0/+2
| | | | | | | | | | The stack list is available in ld.so since commit 1daccf403b1bd86370eb94edca794dc106d02039 ("nptl: Move stack list variables into _rtld_global"), so it's possible to walk the stack list directly in ld.so and perform the initialization there. This eliminates an unprotected function pointer from _rtld_global and reduces the libpthread initialization code.
* elf: Introduce __tls_init_tp for second-phase TCB initializationFlorian Weimer2021-04-211-12/+2
| | | | | | | | | | TLS_INIT_TP is processor-specific, so it is not a good place to put thread library initialization code (it would have to be repeated for all CPUs). Introduce __tls_init_tp as a separate function, to be called immediately after TLS_INIT_TP. Move the existing stack list setup code for NPTL to this function. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* dlfcn: dlerror needs to call free from the base namespace [BZ #24773]Florian Weimer2021-04-211-0/+1
| | | | | | | | | | | | Calling free directly may end up freeing a pointer allocated by the dynamic loader using malloc from libc.so in the base namespace using the allocator from libc.so in a secondary namespace, which results in crashes. This commit redirects the free call through GLRO and the dynamic linker, to reach the correct namespace. It also cleans up the dlerror handling along the way, so that pthread_setspecific is no longer needed (which avoids triggering bug 24774).
* dlfcn: Failures after dlmopen should not terminate process [BZ #24772]Florian Weimer2021-04-211-0/+1
| | | | | | | | | | | | | | | | | | | Commit 9e78f6f6e7134a5f299cc8de77370218f8019237 ("Implement _dl_catch_error, _dl_signal_error in libc.so [BZ #16628]") has the side effect that distinct namespaces, as created by dlmopen, now have separate implementations of the rtld exception mechanism. This means that the call to _dl_catch_error from libdl in a secondary namespace does not actually install an exception handler because the thread-local variable catch_hook in the libc.so copy in the secondary namespace is distinct from that of the base namepace. As a result, a dlsym/dlopen/... failure in a secondary namespace terminates the process with a dynamic linker error because it looks to the exception handler mechanism as if no handler has been installed. This commit restores GLRO (dl_catch_error) and uses it to set the handler in the base namespace. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* ld.so: Implement the --list-diagnostics optionFlorian Weimer2021-03-021-6/+12
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* ld.so: Add --list-tunables to print tunable valuesH.J. Lu2021-01-151-0/+19
| | | | | | Pass --list-tunables to ld.so to print tunables with min and max values. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* Update copyright dates with scripts/update-copyrightsPaul Eggert2021-01-021-1/+1
| | | | | | | | | | | | | | | | 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 6694 files FOO. I then removed trailing white space from benchtests/bench-pthread-locks.c and iconvdata/tst-iconv-big5-hkscs-to-2ucs4.c, to work around this diagnostic from Savannah: remote: *** pre-commit check failed ... remote: *** error: lines with trailing whitespace found remote: error: hook declined to update refs/heads/master
* elf: Record libc.so link map when it is the main program (bug 20972)Florian Weimer2020-12-151-0/+11
| | | | | | | | | | Otherwise, it will not participate in the dependency sorting. Fixes commit 9ffa50b26b0cb5d3043adf6d3d0b1ea735acc147 ("elf: Include libc.so.6 as main program in dependency sort (bug 20972)"). Reviewed-by: Carlos O'Donell <carlos@redhat.com>
* elf: Pass the fd to note processingSzabolcs Nagy2020-12-111-2/+2
| | | | | | | | | | | | | | To handle GNU property notes on aarch64 some segments need to be mmaped again, so the fd of the loaded ELF module is needed. When the fd is not available (kernel loaded modules), then -1 is passed. The fd is passed to both _dl_process_pt_gnu_property and _dl_process_pt_note for consistency. Target specific note processing functions are updated accordingly. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* elf: Add glibc-hwcaps support for LD_LIBRARY_PATHFlorian Weimer2020-12-041-0/+18
| | | | | | | | | | | | | | | | | | | | This hacks non-power-set processing into _dl_important_hwcaps. Once the legacy hwcaps handling goes away, the subdirectory handling needs to be reworked, but it is premature to do this while both approaches are still supported. ld.so supports two new arguments, --glibc-hwcaps-prepend and --glibc-hwcaps-mask. Each accepts a colon-separated list of glibc-hwcaps subdirectory names. The prepend option adds additional subdirectories that are searched first, in the specified order. The mask option restricts the automatically selected subdirectories to those listed in the option argument. For example, on systems where /usr/lib64 is on the library search path, --glibc-hwcaps-prepend=valgrind:debug causes the dynamic loader to search the directories /usr/lib64/glibc-hwcaps/valgrind and /usr/lib64/glibc-hwcaps/debug just before /usr/lib64 is searched. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* nptl: Move stack list variables into _rtld_globalFlorian Weimer2020-11-161-0/+12
| | | | | | | | | Now __thread_gscope_wait (the function behind THREAD_GSCOPE_WAIT, formerly __wait_lookup_done) can be implemented directly in ld.so, eliminating the unprotected GL (dl_wait_lookup_done) function pointer. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* rtld: fix typo in commentRolf Eike Beer2020-10-131-1/+1
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