glibc

Tree: 42e48e720c

Author	SHA1	Message	Date
Paul Eggert	dff8da6b3e	Update copyright dates with scripts/update-copyrights	2 years ago
Joseph Myers	6d7e8eda9b	Update copyright dates with scripts/update-copyrights	3 years ago
Florian Weimer	659fe9fdd1	stdio-common: Introduce buffers for implementing printf These buffers will eventually be used instead of FILE * objects to implement printf functions. The multibyte buffer is struct __printf_buffer, the wide buffer is struct __wprintf_buffer. To enable writing type-generic code, the header files printf_buffer-char.h and printf_buffer-wchar_t.h define the Xprintf macro differently, enabling Xprintf (buffer) to stand for __printf_buffer and __wprintf_buffer as appropriate. For common cases, macros like Xprintf_buffer are provided as a more syntactically convenient shortcut. Buffer-specific flush callbacks are implemented with a switch statement instead of a function pointer, to avoid hardening issues similar to those of libio vtables. struct __printf_buffer_as_file is needed to support custom printf specifiers because the public interface for that requires passing a FILE , which is why there is a trapdoor back from these buffers to FILE streams. Since the immediate user of these interfaces knows when processing has finished, there is no flush callback for the end of processing, only a flush callback for the intermediate buffer flush. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>	3 years ago
Jason A. Donenfeld	eaad4f9e8f	arc4random: simplify design for better safety Rather than buffering 16 MiB of entropy in userspace (by way of chacha20), simply call getrandom() every time. This approach is doubtlessly slower, for now, but trying to prematurely optimize arc4random appears to be leading toward all sorts of nasty properties and gotchas. Instead, this patch takes a much more conservative approach. The interface is added as a basic loop wrapper around getrandom(), and then later, the kernel and libc together can work together on optimizing that. This prevents numerous issues in which userspace is unaware of when it really must throw away its buffer, since we avoid buffering all together. Future improvements may include userspace learning more from the kernel about when to do that, which might make these sorts of chacha20-based optimizations more possible. The current heuristic of 16 MiB is meaningless garbage that doesn't correspond to anything the kernel might know about. So for now, let's just do something conservative that we know is correct and won't lead to cryptographic issues for users of this function. This patch might be considered along the lines of, "optimization is the root of all evil," in that the much more complex implementation it replaces moves too fast without considering security implications, whereas the incremental approach done here is a much safer way of going about things. Once this lands, we can take our time in optimizing this properly using new interplay between the kernel and userspace. getrandom(0) is used, since that's the one that ensures the bytes returned are cryptographically secure. But on systems without it, we fallback to using /dev/urandom. This is unfortunate because it means opening a file descriptor, but there's not much of a choice. Secondly, as part of the fallback, in order to get more or less the same properties of getrandom(0), we poll on /dev/random, and if the poll succeeds at least once, then we assume the RNG is initialized. This is a rough approximation, as the ancient "non-blocking pool" initialized after the "blocking pool", not before, and it may not port back to all ancient kernels, though it does to all kernels supported by glibc (≥3.2), so generally it's the best approximation we can do. The motivation for including arc4random, in the first place, is to have source-level compatibility with existing code. That means this patch doesn't attempt to litigate the interface itself. It does, however, choose a conservative approach for implementing it. Cc: Adhemerval Zanella Netto <adhemerval.zanella@linaro.org> Cc: Florian Weimer <fweimer@redhat.com> Cc: Cristian Rodríguez <crrodriguez@opensuse.org> Cc: Paul Eggert <eggert@cs.ucla.edu> Cc: Mark Harris <mark.hsj@gmail.com> Cc: Eric Biggers <ebiggers@kernel.org> Cc: linux-crypto@vger.kernel.org Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>	4 years ago
Adhemerval Zanella Netto	6f4e0fcfa2	stdlib: Add arc4random, arc4random_buf, and arc4random_uniform (BZ #4417 ) The implementation is based on scalar Chacha20 with per-thread cache. It uses getrandom or /dev/urandom as fallback to get the initial entropy, and reseeds the internal state on every 16MB of consumed buffer. To improve performance and lower memory consumption the per-thread cache is allocated lazily on first arc4random functions call, and if the memory allocation fails getentropy or /dev/urandom is used as fallback. The cache is also cleared on thread exit iff it was initialized (so if arc4random is not called it is not touched). Although it is lock-free, arc4random is still not async-signal-safe (the per thread state is not updated atomically). The ChaCha20 implementation is based on RFC8439 [1], omitting the final XOR of the keystream with the plaintext because the plaintext is a stream of zeros. This strategy is similar to what OpenBSD arc4random does. The arc4random_uniform is based on previous work by Florian Weimer, where the algorithm is based on Jérémie Lumbroso paper Optimal Discrete Uniform Generation from Coin Flips, and Applications (2013) [2], who credits Donald E. Knuth and Andrew C. Yao, The complexity of nonuniform random number generation (1976), for solving the general case. The main advantage of this method is the that the unit of randomness is not the uniform random variable (uint32_t), but a random bit. It optimizes the internal buffer sampling by initially consuming a 32-bit random variable and then sampling byte per byte. Depending of the upper bound requested, it might lead to better CPU utilization. Checked on x86_64-linux-gnu, aarch64-linux, and powerpc64le-linux-gnu. Co-authored-by: Florian Weimer <fweimer@redhat.com> Reviewed-by: Yann Droneaud <ydroneaud@opteya.com> [1] https://datatracker.ietf.org/doc/html/rfc8439 [2] https://arxiv.org/pdf/1304.1916.pdf	4 years ago
Adhemerval Zanella	9deec7c8ba	string: Remove old TLS usage on strsignal The per-thread state is refactored two use two strategies: 1. The default one uses a TLS structure, which will be placed in the static TLS space (using __thread keyword). 2. Linux allocates via struct pthread and access it through THREAD_* macros. The default strategy has the disadvantage of increasing libc.so static TLS consumption and thus decreasing the possible surplus used in some scenarios (which might be mitigated by BZ#25051 fix). It is used only on Hurd, where accessing the thread storage in the in single thread case is not straightforward (afaiu, Hurd developers could correct me here). The fallback static allocation used for allocation failure is also removed: defining its size is problematic without synchronizing with translated messages (to avoid partial translation) and the resulting usage is not thread-safe. Checked on x86-64-linux-gnu, i686-linux-gnu, powerpc64le-linux-gnu, and s390x-linux-gnu. Tested-by: Carlos O'Donell <carlos@redhat.com> Reviewed-by: Carlos O'Donell <carlos@redhat.com>	6 years ago
Adhemerval Zanella	be668a8d78	New exp10f version without SVID compat wrapper This patch changes the exp10f error handling semantics to only set errno according to POSIX rules. New symbol version is introduced at GLIBC_2.32. The old wrappers are kept for compat symbols. There are some outliers that need special handling: - ia64 provides an optimized implementation of exp10f that uses ia64 specific routines to set SVID compatibility. The new symbol version is aliased to the exp10f one. - m68k also provides an optimized implementation, and the new version uses it instead of the sysdeps/ieee754/flt32 one. - riscv and csky uses the generic template implementation that does not provide SVID support. For both cases a new exp10f version is not added, but rather the symbols version of the generic sysdeps/ieee754/flt32 is adjusted instead. Checked on aarch64-linux-gnu, x86_64-linux-gnu, i686-linux-gnu, powerpc64le-linux-gnu.	6 years ago
Adhemerval Zanella	1bdda52fe9	elf: Move vDSO setup to rtld (BZ#24967) This patch moves the vDSO setup from libc to loader code, just after the vDSO link_map setup. For static case the initialization is moved to _dl_non_dynamic_init instead. Instead of using the mangled pointer, the vDSO data is set as attribute_relro (on _rtld_global_ro for shared or _dl_vdso_* for static). It is read-only even with partial relro. It fixes BZ#24967 now that the vDSO pointer is setup earlier than malloc interposition is called. Also, vDSO calls should not be a problem for static dlopen as indicated by BZ#20802. The vDSO pointer would be zero-initialized and the syscall will be issued instead. Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu, arm-linux-gnueabihf, powerpc64le-linux-gnu, powerpc64-linux-gnu, powerpc-linux-gnu, s390x-linux-gnu, sparc64-linux-gnu, and sparcv9-linux-gnu. I also run some tests on mips. Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>	6 years ago
Joseph Myers	2ad7600be7	Move mips from ports to libc. I've moved the MIPS port from ports to the main sysdeps hierarchy. Beyond the README update, the move of the files was simply git mv ports/sysdeps/mips sysdeps/mips git mv ports/sysdeps/unix/mips sysdeps/unix/mips git mv ports/sysdeps/unix/sysv/linux/mips sysdeps/unix/sysv/linux/mips and in addition to the ChangeLog entries here, I put a note at the top of ports/ChangeLog.mips similar to those in other files. Tested that disassembly of installed shared libraries for mips is the same before and after this patch (except for ld.so where paths in assertions are involved, as for arm). * sysdeps/mips: Move directory from ports/sysdeps/mips. * sysdeps/unix/mips: Move directory from ports/sysdeps/unix/mips. * sysdeps/unix/sysv/linux/mips: Move directory from ports/sysdeps/unix/sysv/linux/mips. * README: Update listing for mips--linux-gnu and mips64--linux-gnu. * sysdeps/mips: Move directory to ../sysdeps/mips. * sysdeps/unix/mips: Move directory to ../sysdeps/unix/mips. * sysdeps/unix/sysv/linux/mips: Move directory to ../sysdeps/unix/sysv/linux/mips.	12 years ago
Joseph Myers	e64ac02c24	Move all files into ports/ subdirectory in preparation for merge with glibc	14 years ago
Joseph Myers	c26e391dd3	Fix statfs64/fstatfs64 for MIPS n64.	15 years ago
Daniel Jacobowitz	f10eff5832	Add ARM EABI port.	21 years ago

3 Commits (42e48e720c78ab75eb8def9e866da52b0ac278df)