linux-user: Fix openat() emulation to correctly detect accesses to /proc
In qemu we catch accesses to files like /proc/cpuinfo or /proc/net/route
and return to the guest contents which would be visible on a real system
(instead what the host would show).
This patch fixes a bug, where for example the accesses
cat /proc////cpuinfo
or
cd /proc && cat cpuinfo
will not be recognized by qemu and where qemu will wrongly show
the contents of the host's /proc/cpuinfo file.
Signed-off-by: Helge Deller <deller@gmx.de>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20230803214450.647040-2-deller@gmx.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 12ebc70..9353268 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -8557,9 +8557,12 @@
}
#endif
-int do_guest_openat(CPUArchState *cpu_env, int dirfd, const char *pathname,
+
+int do_guest_openat(CPUArchState *cpu_env, int dirfd, const char *fname,
int flags, mode_t mode, bool safe)
{
+ g_autofree char *proc_name = NULL;
+ const char *pathname;
struct fake_open {
const char *filename;
int (*fill)(CPUArchState *cpu_env, int fd);
@@ -8585,6 +8588,14 @@
{ NULL, NULL, NULL }
};
+ /* if this is a file from /proc/ filesystem, expand full name */
+ proc_name = realpath(fname, NULL);
+ if (proc_name && strncmp(proc_name, "/proc/", 6) == 0) {
+ pathname = proc_name;
+ } else {
+ pathname = fname;
+ }
+
if (is_proc_myself(pathname, "exe")) {
if (safe) {
return safe_openat(dirfd, exec_path, flags, mode);
