1From 6609858239b8f94e12c19eac0cec425511d1211f Mon Sep 17 00:00:00 2001
2From: Hongxu Jia <hongxu.jia@windriver.com>
3Date: Sun, 29 Aug 2021 20:49:16 +0800
4Subject: [PATCH] fix create thread failed in unprivileged process [BZ #28287]
5
6Since commit [d8ea0d0168 Add an internal wrapper for clone, clone2 and clone3]
7applied, start a unprivileged container (docker run without --privileged),
8it creates a thread failed in container.
9
10In commit d8ea0d0168, it calls __clone3 if HAVE_CLONE3_WAPPER is defined.  If
11__clone3 returns -1 with ENOSYS, fall back to clone or clone2.
12
13As known from [1], cloneXXX fails with EPERM if CLONE_NEWCGROUP,
14CLONE_NEWIPC, CLONE_NEWNET, CLONE_NEWNS, CLONE_NEWPID, or CLONE_NEWUTS
15was specified by an unprivileged process (process without CAP_SYS_ADMIN)
16
17[1] https://man7.org/linux/man-pages/man2/clone3.2.html
18
19So if __clone3 returns -1 with EPERM, fall back to clone or clone2 could
20fix the issue. Here are the test steps:
21
221) Prepare test code
23cat > conftest.c <<ENDOF
24 #include <pthread.h>
25 #include <stdio.h>
26
27int check_me = 0;
28void* func(void* data) {check_me = 42; printf("start thread: check_me %d\n", check_me); return &check_me;}
29int main()
30{
31  pthread_t t;
32  void *ret;
33  pthread_create (&t, 0, func, 0);
34  pthread_join (t, &ret);
35  printf("check_me %d, p %p\n", check_me, &ret);
36  return (check_me != 42 || ret != &check_me);
37}
38
39ENDOF
40
412) Compile
42gcc -o conftest -pthread conftest.c
43
443) Start a container with glibc 2.34 installed
45[skip details]
46docker run -it <container-image-name> bash
47
484) Run conftest without this patch
49$ ./conftest
50check_me 0, p 0x7ffd91ccd400
51
525) Run conftest with this patch
53$ ./conftest
54start thread: check_me 42
55check_me 42, p 0x7ffe253c6f20
56
57Upstream-Status: Inappropriate [Rejected by upstream]
58
59Upstream glibc rejected it because the latest docker has resolved the issue [1],
60and upstream glibc does not backward compatibility with old docker[2]
61
62In order to build Yocto with uninative in old docker, we need this local
63patch
64
65[1] https://github.com/moby/moby/commit/9f6b562dd12ef7b1f9e2f8e6f2ab6477790a6594
66[2] https://sourceware.org/pipermail/libc-alpha/2021-August/130590.html
67
68Signed-off-by: Hongxu Jia <hongxu.jia@windriver.com>
69---
70 sysdeps/unix/sysv/linux/clone-internal.c | 2 +-
71 1 file changed, 1 insertion(+), 1 deletion(-)
72
73diff --git a/sysdeps/unix/sysv/linux/clone-internal.c b/sysdeps/unix/sysv/linux/clone-internal.c
74index a71effcbd3..a0569113aa 100644
75--- a/sysdeps/unix/sysv/linux/clone-internal.c
76+++ b/sysdeps/unix/sysv/linux/clone-internal.c
77@@ -52,7 +52,7 @@ __clone_internal (struct clone_args *cl_args,
78   /* Try clone3 first.  */
79   int saved_errno = errno;
80   ret = __clone3 (cl_args, sizeof (*cl_args), func, arg);
81-  if (ret != -1 || errno != ENOSYS)
82+  if (ret != -1 || (errno != ENOSYS && errno != EPERM))
83     return ret;
84
85   /* NB: Restore errno since errno may be checked against non-zero
86--
872.27.0
88
89