From ffbb37732807e180b14a21d1bf79ad5038252c02 Mon Sep 17 00:00:00 2001 From: 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 < #include 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 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 Signed-off-by: Khem Raj --- 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