Merge remote-tracking branch 'remotes/dgilbert/tags/pull-migration-20200828a' into staging

Migration and virtiofsd pull 2020-08-28

Migration:
   vsock support for migration
   minor fixes

virtiofsd:
   Disable remote posix locks by default - because we
     never supported blocking variants and this breaks things
   Some prep work for un/less priviliged modes

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

# gpg: Signature made Fri 28 Aug 2020 13:43:18 BST
# gpg:                using RSA key 45F5C71B4A0CB7FB977A9FA90516331EBC5BFDE7
# gpg: Good signature from "Dr. David Alan Gilbert (RH2) <dgilbert@redhat.com>" [full]
# Primary key fingerprint: 45F5 C71B 4A0C B7FB 977A  9FA9 0516 331E BC5B FDE7

* remotes/dgilbert/tags/pull-migration-20200828a:
  virtiofsd: probe unshare(CLONE_FS) and print an error
  virtiofsd: drop CAP_DAC_READ_SEARCH
  virtiofsd: Remove "norace" from cmdline help and docs
  virtiofsd: Disable remote posix locks by default
  migration: tls: fix memory leak in migration_tls_get_creds
  migration: improve error reporting of block driver state name
  migration: add vsock as data channel support
  migration: unify the framework of socket-type channel

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

3 files changed, 17 insertions, 4 deletions

diff --git a/tools/virtiofsd/fuse_virtio.c b/tools/virtiofsd/fuse_virtio.c
index 3b6d16a..9e55375 100644
--- a/tools/virtiofsd/fuse_virtio.c
+++ b/tools/virtiofsd/fuse_virtio.c
@@ -949,6 +949,22 @@ int virtio_session_mount(struct fuse_session *se)
 {
     int ret;
 
+    /*
+     * Test that unshare(CLONE_FS) works. fv_queue_worker() will need it. It's
+     * an unprivileged system call but some Docker/Moby versions are known to
+     * reject it via seccomp when CAP_SYS_ADMIN is not given.
+     *
+     * Note that the program is single-threaded here so this syscall has no
+     * visible effect and is safe to make.
+     */
+    ret = unshare(CLONE_FS);
+    if (ret == -1 && errno == EPERM) {
+        fuse_log(FUSE_LOG_ERR, "unshare(CLONE_FS) failed with EPERM. If "
+                "running in a container please check that the container "
+                "runtime seccomp policy allows unshare.\n");
+        return -1;
+    }
+
     ret = fv_create_listen_socket(se);
     if (ret < 0) {
         return ret;
diff --git a/tools/virtiofsd/helper.c b/tools/virtiofsd/helper.c
index 3105b6c..7bc5d7d 100644
--- a/tools/virtiofsd/helper.c
+++ b/tools/virtiofsd/helper.c
@@ -159,8 +159,6 @@ void fuse_cmdline_help(void)
            "    -o max_idle_threads        the maximum number of idle worker "
            "threads\n"
            "                               allowed (default: 10)\n"
-           "    -o norace                  disable racy fallback\n"
-           "                               default: false\n"
            "    -o posix_lock|no_posix_lock\n"
            "                               enable/disable remote posix lock\n"
            "                               default: posix_lock\n"
diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
index 63d1d00..784330e0 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -2596,7 +2596,6 @@ static void setup_capabilities(char *modcaps_in)
     if (capng_updatev(CAPNG_ADD, CAPNG_PERMITTED | CAPNG_EFFECTIVE,
             CAP_CHOWN,
             CAP_DAC_OVERRIDE,
-            CAP_DAC_READ_SEARCH,
             CAP_FOWNER,
             CAP_FSETID,
             CAP_SETGID,
@@ -2823,7 +2822,7 @@ int main(int argc, char *argv[])
     struct lo_data lo = {
         .debug = 0,
         .writeback = 0,
-        .posix_lock = 1,
+        .posix_lock = 0,
         .proc_self_fd = -1,
     };
     struct lo_map_elem *root_elem;