cd02f96b87
The current Busybox version (1.36.0) fails to build with some
libc/linux combinations where getrandom() is not available. Two fixes
for glibc already exists upstream, so backport them here. A third
one (submitted upstream, not part of the main branch yet) was needed
to be able to compile with older musl and uClibc versions (or older
kernels).
This fixes the following build failure raised since commit
d68b617993:
miscutils/seedrng.c:45:24: fatal error: sys/random.h: No such file or directory
#include <sys/random.h>
Fixes:
- http://autobuild.buildroot.net/results/44a0476b86c579e6aa658f156f0292958d40513c
- http://autobuild.buildroot.net/results/ed028160db397581558fd8c96755621dd8298bb1
- https://gitlab.com/buildroot.org/buildroot/-/jobs/4122624008
- https://gitlab.com/buildroot.org/buildroot/-/jobs/4122624034
- https://gitlab.com/buildroot.org/buildroot/-/jobs/4122624044
- https://gitlab.com/buildroot.org/buildroot/-/jobs/4122624048
- https://gitlab.com/buildroot.org/buildroot/-/jobs/4122624051
It also fixes the following (similar) build failure, raised since the
same commit:
miscutils/lib.a(seedrng.o): In function `seedrng_main':
seedrng.c:(.text.seedrng_main+0x26c): undefined reference to `getrandom'
seedrng.c:(.text.seedrng_main+0x2e8): undefined reference to `getrandom'
collect2: error: ld returned 1 exit status
Fixes:
- https://gitlab.com/buildroot.org/buildroot/-/jobs/4122624028
- https://gitlab.com/buildroot.org/buildroot/-/jobs/4122624031
Signed-off-by: Raphaël Mélotte <raphael.melotte@mind.be>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
125 lines
4.7 KiB
Diff
125 lines
4.7 KiB
Diff
From b2d26d449ec855602b9a88f58c2eb675de0224f2 Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Rapha=C3=ABl=20M=C3=A9lotte?= <raphael.melotte@mind.be>
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Date: Tue, 18 Apr 2023 15:54:43 +0200
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Subject: [PATCH v4] seedrng: fix getrandom() detection for non-glibc libc
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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glibc <= 2.24 does not provide getrandom(). A check for it has been
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added in 200a9669fbf6f06894e4243cccc9fc11a1a6073a and fixed in
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cb57abb46f06f4ede8d9ccbdaac67377fdf416cf.
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However, building with a libc other than glibc can lead to the same
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problem as not every other libc has getrandom() either:
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- uClibc provides it from v1.0.2 onwards, but requires to define
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_GNU_SOURCE (all versions - we already define it by default), and
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stddef to be included first (when using uClibc < 1.0.35 - we already
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include it through libbb.h).
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- musl libc has getrandom(), but only from version 1.1.20 onwards. As
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musl does not provide __MUSL__ or version information, it's not
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possible to check for it like we did for glibc.
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All of this makes it difficult (or impossible in case of musl) to
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check what we need to do to have getrandom() based on each libc
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versions.
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On top of that, getrandom() is also not available on older kernels. As
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an example, when using a 3.10 kernel with uClibc 1.0.26, getrandom()
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is declared so compiling works, but it fails at link time because
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getrandom() is not defined.
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To make it easier, take a similar approach to what was done for the
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crypt library: try to build a sample program to see if we have
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getrandom(). To keep it compatible with different versions of
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make (for reference see [1]), a variable for '#' is also introduced.
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Based on the new Makefile variable, we now either use the
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libc-provided getrandom() when it's available, or use our own
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implementation when it's not (like it was the case already for glibc <
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2.25).
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This should fix compiling with many libc/kernel combinations.
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[1]: https://git.savannah.gnu.org/cgit/make.git/commit/?id=c6966b323811c37acedff05b576b907b06aea5f4
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Signed-off-by: Raphaël Mélotte <raphael.melotte@mind.be>
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Upstream: http://lists.busybox.net/pipermail/busybox/2023-May/090317.html
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---
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Changes v3 -> v4:
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- use a variable for '#' for compatibility with GNU make 4.2.1 and earlier.
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Changes v2 -> v3:
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- fix _GNU_SOURCE define location
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Changes v1 -> v2:
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- move _GNU_SOURCE to bb_libtest.c
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- remove GRND_NONBLOCK
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Note that I was not able to test every single combination, but I could
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confirm it builds successfully for:
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uClibc 10.0.24, linux headers 3.10 (libc getrandom NOT used)
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uClibc 1.0.36, linux headers 4.9 (libc getrandom used)
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musl 1.1.16, linux headers 4.12 (libc getrandom NOT used)
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musl 1.2.1, linux headers (libc getrandom used)
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glibc 2.25, linux headers 4.10 (libc getrandom used)
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Makefile.flags | 12 ++++++++++++
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miscutils/seedrng.c | 8 ++++----
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2 files changed, 16 insertions(+), 4 deletions(-)
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diff --git a/Makefile.flags b/Makefile.flags
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index 1cec5ba20..0d437303a 100644
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--- a/Makefile.flags
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+++ b/Makefile.flags
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@@ -161,6 +161,18 @@ ifeq ($(RT_AVAILABLE),y)
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LDLIBS += rt
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endif
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+# GNU Make version 4.2.1 and earlier require number signs ('#')
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+# inside function invocations to be escaped, while versions 4.3+
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+# require them to be unescaped. Use a variable for it so that it works
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+# for both versions:
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+C := \#
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+# Not all libc versions have getrandom, so check for it:
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+HAVE_GETRANDOM := $(shell printf '$Cdefine _GNU_SOURCE\n$Cinclude <stddef.h>\n$Cinclude <sys/random.h>\nint main(void){char buf[256];\ngetrandom(buf,sizeof(buf),0);}' >bb_libtest.c; $(CC) $(CFLAGS) $(CFLAGS_busybox) -o /dev/null bb_libtest.c >/dev/null 2>&1 && echo "y"; rm bb_libtest.c)
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+
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+ifeq ($(HAVE_GETRANDOM),y)
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+CFLAGS += -DHAVE_GETRANDOM
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+endif
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+
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# libpam may use libpthread, libdl and/or libaudit.
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# On some platforms that requires an explicit -lpthread, -ldl, -laudit.
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# However, on *other platforms* it fails when some of those flags
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diff --git a/miscutils/seedrng.c b/miscutils/seedrng.c
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index 3bf6e2ea7..2f1e18c32 100644
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--- a/miscutils/seedrng.c
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+++ b/miscutils/seedrng.c
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@@ -44,8 +44,10 @@
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#include <linux/random.h>
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#include <sys/file.h>
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-/* Fix up glibc <= 2.24 not having getrandom() */
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-#if defined(__GLIBC__) && __GLIBC__ == 2 && __GLIBC_MINOR__ <= 24
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+/* Fix up some libc (e.g. glibc <= 2.24) not having getrandom() */
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+#if defined HAVE_GETRANDOM
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+#include <sys/random.h>
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+#else /* No getrandom */
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#include <sys/syscall.h>
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static ssize_t getrandom(void *buffer, size_t length, unsigned flags)
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{
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@@ -56,8 +58,6 @@ static ssize_t getrandom(void *buffer, size_t length, unsigned flags)
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return -1;
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# endif
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}
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-#else
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-#include <sys/random.h>
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#endif
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/* Apparently some headers don't ship with this yet. */
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--
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2.39.1
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