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machined: when reading os-release file, join PID namespace too

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This is required for /proc/self/fd/xyz to work, but that's what we need
to convert the O_PATH fd returned by chase_symlinks() back to a regular
file fd. Hence, let's do the joining of the namespaces fully and
correctly, by doing fork()+setns()+fork() with the PID and fs
namespaces.

This makes use of the new namespace_fork() helper we just added.

Fixes: #10549
This commit is contained in:
Lennart Poettering
2018-11-13 10:49:18 +01:00
parent 0a885dd055
commit 2bb21fc928
1 changed files with 6 additions and 8 deletions
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src/machine/machine-dbus.c
+6 -8
View File
@@ -333,19 +333,21 @@ int bus_machine_method_get_os_release(sd_bus_message *message, void *userdata, s
break;
case MACHINE_CONTAINER: {
_cleanup_close_ int mntns_fd = -1, root_fd = -1;
_cleanup_close_ int mntns_fd = -1, root_fd = -1, pidns_fd = -1;
_cleanup_close_pair_ int pair[2] = { -1, -1 };
_cleanup_fclose_ FILE *f = NULL;
pid_t child;
r = namespace_open(m->leader, NULL, &mntns_fd, NULL, NULL, &root_fd);
r = namespace_open(m->leader, &pidns_fd, &mntns_fd, NULL, NULL, &root_fd);
if (r < 0)
return r;
if (socketpair(AF_UNIX, SOCK_SEQPACKET, 0, pair) < 0)
return -errno;
r = safe_fork("(sd-osrel)", FORK_RESET_SIGNALS|FORK_DEATHSIG, &child);
r = namespace_fork("(sd-osrelns)", "(sd-osrel)", NULL, 0, FORK_RESET_SIGNALS|FORK_DEATHSIG,
pidns_fd, mntns_fd, -1, -1, root_fd,
&child);
if (r < 0)
return sd_bus_error_set_errnof(error, r, "Failed to fork(): %m");
if (r == 0) {
@@ -353,10 +355,6 @@ int bus_machine_method_get_os_release(sd_bus_message *message, void *userdata, s
pair[0] = safe_close(pair[0]);
r = namespace_enter(-1, mntns_fd, -1, -1, root_fd);
if (r < 0)
_exit(EXIT_FAILURE);
r = open_os_release(NULL, NULL, &fd);
if (r == -ENOENT)
_exit(EXIT_NOT_FOUND);
@@ -382,7 +380,7 @@ int bus_machine_method_get_os_release(sd_bus_message *message, void *userdata, s
if (r < 0)
return r;
r = wait_for_terminate_and_check("(sd-osrel)", child, 0);
r = wait_for_terminate_and_check("(sd-osrelns)", child, 0);
if (r < 0)
return sd_bus_error_set_errnof(error, r, "Failed to wait for child: %m");
if (r == EXIT_NOT_FOUND)