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authorLennart Poettering <lennart@poettering.net>2013-12-13 22:02:47 +0100
committerLennart Poettering <lennart@poettering.net>2013-12-14 05:10:25 +0100
commitbc9fd78c7bfc39881e19457e476393635f8b0442 (patch)
tree3c4dc6461460a2b4094516eb35424d36f52f455a /src/shared/util.c
parent3fa5dd6de798e17d93531bc900b8e2dc587c38f3 (diff)
bus: when connecting to a container's kdbus instance, enter namespace first
Previously we'd open the connection in the originating namespace, which meant most peers of the bus would not be able to make sense of the PID/UID/... identity of us since we didn't exist in the namespace they run in. However they require this identity for privilege decisions, hence disallowing access to anything from the host. Instead, when connecting to a container, create a temporary subprocess, make it join the container's namespace and then connect from there to the kdbus instance. This is similar to how we do it for socket conections already. THis also unifies the namespacing code used by machinectl and the bus APIs.
Diffstat (limited to 'src/shared/util.c')
-rw-r--r--src/shared/util.c73
1 files changed, 73 insertions, 0 deletions
diff --git a/src/shared/util.c b/src/shared/util.c
index 1c35edfbb1..66276aa54e 100644
--- a/src/shared/util.c
+++ b/src/shared/util.c
@@ -5951,3 +5951,76 @@ int proc_cmdline(char **ret) {
return 1;
}
+
+int container_get_leader(const char *machine, pid_t *pid) {
+ _cleanup_free_ char *s = NULL, *class = NULL;
+ const char *p;
+ pid_t leader;
+ int r;
+
+ assert(machine);
+ assert(pid);
+
+ p = strappenda("/run/systemd/machines/", machine);
+ r = parse_env_file(p, NEWLINE, "LEADER", &s, "CLASS", &class, NULL);
+ if (r == -ENOENT)
+ return -EHOSTDOWN;
+ if (r < 0)
+ return r;
+ if (!s)
+ return -EIO;
+
+ if (!streq_ptr(class, "container"))
+ return -EIO;
+
+ r = parse_pid(s, &leader);
+ if (r < 0)
+ return r;
+ if (leader <= 1)
+ return -EIO;
+
+ *pid = leader;
+ return 0;
+}
+
+int namespace_open(pid_t pid, int *namespace_fd, int *root_fd) {
+ _cleanup_close_ int nsfd = -1;
+ const char *ns, *root;
+ int rfd;
+
+ assert(pid >= 0);
+ assert(namespace_fd);
+ assert(root_fd);
+
+ ns = procfs_file_alloca(pid, "ns/mnt");
+ nsfd = open(ns, O_RDONLY|O_NOCTTY|O_CLOEXEC);
+ if (nsfd < 0)
+ return -errno;
+
+ root = procfs_file_alloca(pid, "root");
+ rfd = open(root, O_RDONLY|O_NOCTTY|O_CLOEXEC|O_DIRECTORY);
+ if (rfd < 0)
+ return -errno;
+
+ *namespace_fd = nsfd;
+ *root_fd = rfd;
+ nsfd = -1;
+
+ return 0;
+}
+
+int namespace_enter(int namespace_fd, int root_fd) {
+ assert(namespace_fd >= 0);
+ assert(root_fd >= 0);
+
+ if (setns(namespace_fd, CLONE_NEWNS) < 0)
+ return -errno;
+
+ if (fchdir(root_fd) < 0)
+ return -errno;
+
+ if (chroot(".") < 0)
+ return -errno;
+
+ return 0;
+}