123 lines
4.9 KiB
Diff
123 lines
4.9 KiB
Diff
From 2115fcc1e673079fe76e949ac0904267075c25a4 Mon Sep 17 00:00:00 2001
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From: Lennart Poettering <lennart@poettering.net>
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Date: Wed, 31 Oct 2018 13:04:20 +0100
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Subject: [PATCH] nspawn: beef up netns checking a bit, for compat with old
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kernels
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Fixes: #10544
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Cherry-picked from: 6619ad889da260cf83079cc74a85d571acd1df5a
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---
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src/basic/stat-util.c | 40 +++++++++++++++++++++++++++++++++++----
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src/nspawn/nspawn.c | 8 +++++---
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src/test/test-stat-util.c | 15 +++++++++++++++
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3 files changed, 56 insertions(+), 7 deletions(-)
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diff --git a/src/basic/stat-util.c b/src/basic/stat-util.c
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index 07154e25bb..26aee9bad6 100644
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--- a/src/basic/stat-util.c
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+++ b/src/basic/stat-util.c
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@@ -204,15 +204,47 @@ int fd_is_network_fs(int fd) {
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}
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int fd_is_network_ns(int fd) {
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+ struct statfs s;
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int r;
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- r = fd_is_fs_type(fd, NSFS_MAGIC);
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- if (r <= 0)
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- return r;
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+ /* Checks whether the specified file descriptor refers to a network namespace. On old kernels there's no nice
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+ * way to detect that, hence on those we'll return a recognizable error (EUCLEAN), so that callers can handle
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+ * this somewhat nicely.
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+ *
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+ * This function returns > 0 if the fd definitely refers to a network namespace, 0 if it definitely does not
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+ * refer to a network namespace, -EUCLEAN if we can't determine, and other negative error codes on error. */
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+
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+ if (fstatfs(fd, &s) < 0)
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+ return -errno;
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+
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+ if (!is_fs_type(&s, NSFS_MAGIC)) {
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+ /* On really old kernels, there was no "nsfs", and network namespace sockets belonged to procfs
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+ * instead. Handle that in a somewhat smart way. */
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+
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+ if (is_fs_type(&s, PROC_SUPER_MAGIC)) {
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+ struct statfs t;
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+
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+ /* OK, so it is procfs. Let's see if our own network namespace is procfs, too. If so, then the
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+ * passed fd might refer to a network namespace, but we can't know for sure. In that case,
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+ * return a recognizable error. */
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+
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+ if (statfs("/proc/self/ns/net", &t) < 0)
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+ return -errno;
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+
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+ if (s.f_type == t.f_type)
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+ return -EUCLEAN; /* It's possible, we simply don't know */
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+ }
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+
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+ return 0; /* No! */
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+ }
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r = ioctl(fd, NS_GET_NSTYPE);
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- if (r < 0)
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+ if (r < 0) {
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+ if (errno == ENOTTY) /* Old kernels didn't know this ioctl, let's also return a recognizable error in that case */
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+ return -EUCLEAN;
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+
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return -errno;
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+ }
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return r == CLONE_NEWNET;
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}
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diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c
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index 56877bd932..8aec893a69 100644
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--- a/src/nspawn/nspawn.c
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+++ b/src/nspawn/nspawn.c
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@@ -3701,10 +3701,12 @@ static int run(int master,
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return log_error_errno(errno, "Cannot open file %s: %m", arg_network_namespace_path);
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r = fd_is_network_ns(netns_fd);
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- if (r < 0 && r != -ENOTTY)
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+ if (r == -EUCLEAN)
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+ log_debug_errno(r, "Cannot determine if passed network namespace path '%s' really refers to a network namespace, assuming it does.", arg_network_namespace_path);
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+ else if (r < 0)
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return log_error_errno(r, "Failed to check %s fs type: %m", arg_network_namespace_path);
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- if (r == 0) {
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- log_error("Path %s doesn't refer to a network namespace", arg_network_namespace_path);
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+ else if (r == 0) {
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+ log_error("Path %s doesn't refer to a network namespace, refusing.", arg_network_namespace_path);
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return -EINVAL;
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}
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}
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diff --git a/src/test/test-stat-util.c b/src/test/test-stat-util.c
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index 43f56a6c20..2b0564d8a0 100644
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--- a/src/test/test-stat-util.c
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+++ b/src/test/test-stat-util.c
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@@ -67,11 +67,26 @@ static void test_path_is_temporary_fs(void) {
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assert_se(path_is_temporary_fs("/i-dont-exist") == -ENOENT);
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}
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+static void test_fd_is_network_ns(void) {
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+ _cleanup_close_ int fd = -1;
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+ assert_se(fd_is_network_ns(STDIN_FILENO) == 0);
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+ assert_se(fd_is_network_ns(STDERR_FILENO) == 0);
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+ assert_se(fd_is_network_ns(STDOUT_FILENO) == 0);
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+
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+ assert_se((fd = open("/proc/self/ns/mnt", O_CLOEXEC|O_RDONLY)) >= 0);
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+ assert_se(IN_SET(fd_is_network_ns(fd), 0, -EUCLEAN));
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+ fd = safe_close(fd);
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+
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+ assert_se((fd = open("/proc/self/ns/net", O_CLOEXEC|O_RDONLY)) >= 0);
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+ assert_se(IN_SET(fd_is_network_ns(fd), 1, -EUCLEAN));
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+}
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+
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int main(int argc, char *argv[]) {
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test_files_same();
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test_is_symlink();
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test_path_is_fs_type();
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test_path_is_temporary_fs();
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+ test_fd_is_network_ns();
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return 0;
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}
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