Re: [PATCH] glibc: fix create thread failed in unprivileged process


Alexander Kanavin
 

This is presumably to support builds on some old distribution, so it
would help if you specify which distribution and which versions of
docker require this. Otherwise we'll never know when we can drop the
patch.

Alex

On Wed, 16 Feb 2022 at 03:54, hongxu <hongxu.jia@...> wrote:

Since upstream commit [d8ea0d0168 Add an internal wrapper for clone, clone2
and clone3] applied, start a unprivileged container (docker run without
--privileged), it creates a thread failed in container.

In commit d8ea0d0168, it calls __clone3 if HAVE_CLONE3_WAPPER is defined. If
__clone3 returns -1 with ENOSYS, fall back to clone or clone2.

As known from [1], cloneXXX fails with EPERM if CLONE_NEWCGROUP,
CLONE_NEWIPC, CLONE_NEWNET, CLONE_NEWNS, CLONE_NEWPID, or CLONE_NEWUTS
was specified by an unprivileged process (process without CAP_SYS_ADMIN)

[1] https://man7.org/linux/man-pages/man2/clone3.2.html

So if __clone3 returns -1 with EPERM, fall back to clone or clone2 could
fix the issue.

Signed-off-by: Hongxu Jia <hongxu.jia@...>
---
...d-failed-in-unprivileged-process-BZ-.patch | 88 +++++++++++++++++++
meta/recipes-core/glibc/glibc_2.35.bb | 1 +
2 files changed, 89 insertions(+)
create mode 100644 meta/recipes-core/glibc/glibc/0024-fix-create-thread-failed-in-unprivileged-process-BZ-.patch

diff --git a/meta/recipes-core/glibc/glibc/0024-fix-create-thread-failed-in-unprivileged-process-BZ-.patch b/meta/recipes-core/glibc/glibc/0024-fix-create-thread-failed-in-unprivileged-process-BZ-.patch
new file mode 100644
index 0000000000..b431ea168d
--- /dev/null
+++ b/meta/recipes-core/glibc/glibc/0024-fix-create-thread-failed-in-unprivileged-process-BZ-.patch
@@ -0,0 +1,88 @@
+From 6609858239b8f94e12c19eac0cec425511d1211f Mon Sep 17 00:00:00 2001
+From: Hongxu Jia <hongxu.jia@...>
+Date: Sun, 29 Aug 2021 20:49:16 +0800
+Subject: [PATCH] fix create thread failed in unprivileged process [BZ #28287]
+
+Since commit [d8ea0d0168 Add an internal wrapper for clone, clone2 and clone3]
+applied, start a unprivileged container (docker run without --privileged),
+it creates a thread failed in container.
+
+In commit d8ea0d0168, it calls __clone3 if HAVE_CLONE3_WAPPER is defined. If
+__clone3 returns -1 with ENOSYS, fall back to clone or clone2.
+
+As known from [1], cloneXXX fails with EPERM if CLONE_NEWCGROUP,
+CLONE_NEWIPC, CLONE_NEWNET, CLONE_NEWNS, CLONE_NEWPID, or CLONE_NEWUTS
+was specified by an unprivileged process (process without CAP_SYS_ADMIN)
+
+[1] https://man7.org/linux/man-pages/man2/clone3.2.html
+
+So if __clone3 returns -1 with EPERM, fall back to clone or clone2 could
+fix the issue. Here are the test steps:
+
+1) Prepare test code
+cat > conftest.c <<ENDOF
+ #include <pthread.h>
+ #include <stdio.h>
+
+int check_me = 0;
+void* func(void* data) {check_me = 42; printf("start thread: check_me %d\n", check_me); return &check_me;}
+int main()
+{
+ pthread_t t;
+ void *ret;
+ pthread_create (&t, 0, func, 0);
+ pthread_join (t, &ret);
+ printf("check_me %d, p %p\n", check_me, &ret);
+ return (check_me != 42 || ret != &check_me);
+}
+
+ENDOF
+
+2) Compile
+gcc -o conftest -pthread conftest.c
+
+3) Start a container with glibc 2.34 installed
+[skip details]
+docker run -it <container-image-name> bash
+
+4) Run conftest without this patch
+$ ./conftest
+check_me 0, p 0x7ffd91ccd400
+
+5) Run conftest with this patch
+$ ./conftest
+start thread: check_me 42
+check_me 42, p 0x7ffe253c6f20
+
+Upstream-Status: Inappropriate [Rejected by upstream]
+
+Upstream glibc rejected it because the latest docker has resolved the issue [1],
+and upstream glibc does not backward compatibility with old docker[2]
+
+In order to build Yocto with uninative in old docker, we need this local
+patch
+
+[1] https://github.com/moby/moby/commit/9f6b562dd12ef7b1f9e2f8e6f2ab6477790a6594
+[2] https://sourceware.org/pipermail/libc-alpha/2021-August/130590.html
+
+Signed-off-by: Hongxu Jia <hongxu.jia@...>
+---
+ sysdeps/unix/sysv/linux/clone-internal.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/sysdeps/unix/sysv/linux/clone-internal.c b/sysdeps/unix/sysv/linux/clone-internal.c
+index a71effcbd3..a0569113aa 100644
+--- a/sysdeps/unix/sysv/linux/clone-internal.c
++++ b/sysdeps/unix/sysv/linux/clone-internal.c
+@@ -52,7 +52,7 @@ __clone_internal (struct clone_args *cl_args,
+ /* Try clone3 first. */
+ int saved_errno = errno;
+ ret = __clone3 (cl_args, sizeof (*cl_args), func, arg);
+- if (ret != -1 || errno != ENOSYS)
++ if (ret != -1 || (errno != ENOSYS && errno != EPERM))
+ return ret;
+
+ /* NB: Restore errno since errno may be checked against non-zero
+--
+2.27.0
+
diff --git a/meta/recipes-core/glibc/glibc_2.35.bb b/meta/recipes-core/glibc/glibc_2.35.bb
index 2903a4001f..b785b61154 100644
--- a/meta/recipes-core/glibc/glibc_2.35.bb
+++ b/meta/recipes-core/glibc/glibc_2.35.bb
@@ -47,6 +47,7 @@ SRC_URI = "${GLIBC_GIT_URI};branch=${SRCBRANCH};name=glibc \
file://0021-Replace-echo-with-printf-builtin-in-nscd-init-script.patch \
file://0022-sysdeps-gnu-configure.ac-Set-libc_cv_rootsbindir-onl.patch \
file://0023-timezone-Make-shell-interpreter-overridable-in-tzsel.patch \
+ file://0024-fix-create-thread-failed-in-unprivileged-process-BZ-.patch \
"
S = "${WORKDIR}/git"
B = "${WORKDIR}/build-${TARGET_SYS}"
--
2.27.0



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