[3/5] linux-user: Fix the execfd case of /proc/self/exe open

Commit Message

Takashi Yamamoto May 24, 2021, 4:54 a.m. UTC

It's problematic to return AT_EXECFD as it is because the user app
would close it.
This patch opens it via /proc/self/fd instead.

Signed-off-by: YAMAMOTO Takashi <[e-mail]>
---
 linux-user/syscall.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

Patch

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index a2b03ecb8b..14a63518e2 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -8118,7 +8118,17 @@  static int do_openat(void *cpu_env, int dirfd, const char *pathname, int flags,
 
     if (is_proc_myself(pathname, "exe")) {
         int execfd = qemu_getauxval(AT_EXECFD);
-        return execfd ? execfd : safe_openat(dirfd, exec_path, flags, mode);
+        if (execfd) {
+            char filename[PATH_MAX];
+            int ret;
+
+            snprintf(filename, sizeof(filename), "/proc/self/fd/%d", execfd);
+            ret = safe_openat(dirfd, filename, flags, mode);
+            if (ret != -1) {
+                return ret;
+            }
+        }
+        return safe_openat(dirfd, exec_path, flags, mode);
     }
 
     for (fake_open = fakes; fake_open->filename; fake_open++) {