Fix build with older python/glibc/bpf and add CI job to cover it (#38500)

.github/workflows/build-test.sh

@@ -124,10 +124,15 @@ fi
 
 # This is added by default, and it is often broken, but we don't need anything from it
 sudo rm -f /etc/apt/sources.list.d/microsoft-prod.{list,sources}
-# add-apt-repository --enable-source does not work on deb822 style sources.
-for f in /etc/apt/sources.list.d/*.sources; do
-    sudo sed -i "s/Types: deb/Types: deb deb-src/g" "$f"
-done
+if grep -q 'VERSION_CODENAME=jammy' /usr/lib/os-release; then
+    sudo add-apt-repository -y --no-update ppa:upstream-systemd-ci/systemd-ci
+    sudo add-apt-repository -y --no-update --enable-source
+else
+    # add-apt-repository --enable-source does not work on deb822 style sources.
+    for f in /etc/apt/sources.list.d/*.sources; do
+        sudo sed -i "s/Types: deb/Types: deb deb-src/g" "$f"
+    done
+fi
 sudo apt-get -y update
 sudo apt-get -y build-dep systemd
 sudo apt-get -y install "${PACKAGES[@]}"
@@ -138,6 +143,11 @@ sudo apt-get -y install "${PACKAGES[@]}"
 pip3 install --user -r .github/workflows/requirements.txt --require-hashes --break-system-packages
 export PATH="$HOME/.local/bin:$PATH"
 
+if [[ -n "$CUSTOM_PYTHON" ]]; then
+    # If CUSTOM_PYTHON is set we need to pull jinja2 from pip, as a local interpreter is used
+    pip3 install --user --break-system-packages jinja2
+fi
+
 $CC --version
 meson --version
 ninja --version

.github/workflows/build-test.yml

@@ -19,12 +19,13 @@ jobs:
   build:
     runs-on: ${{ matrix.runner }}
     concurrency:
-      group: ${{ github.workflow }}-${{ toJSON(matrix.env) }}-${{ github.ref }}-${{ matrix.runner }}
+      group: ${{ github.workflow }}-${{ toJSON(matrix.env) }}-${{ github.ref }}-${{ matrix.runner }}-${{ matrix.python-version }}
       cancel-in-progress: true
     strategy:
       fail-fast: false
       matrix:
         runner: [ ubuntu-24.04 ]
+        python-version: [ '' ]
         env:
           - { COMPILER: "gcc",   COMPILER_VERSION: "11", LINKER: "bfd"  }
           - { COMPILER: "gcc",   COMPILER_VERSION: "13", LINKER: "mold" }
@@ -34,13 +35,26 @@ jobs:
         include:
           - env: { COMPILER: "gcc",   COMPILER_VERSION: "11", LINKER: "bfd"  }
             runner: [ ubuntu-24.04-ppc64le ]
+            python-version: ''
           - env: { COMPILER: "gcc",   COMPILER_VERSION: "13", LINKER: "mold"  }
             runner: [ ubuntu-24.04-arm ]
+            python-version: ''
           - env: { COMPILER: "clang", COMPILER_VERSION: "18", LINKER: "lld"  }
             runner: [ ubuntu-24.04-s390x ]
+            python-version: ''
+          # Do one run with the oldest supported python version to ensure there are no regressions
+          # It is only available on Jammy, which is useful as it will also provide a build check for
+          # older glibc
+          - env: { COMPILER: "gcc",   COMPILER_VERSION: "12", LINKER: "bfd", CUSTOM_PYTHON: "1"  }
+            runner: [ ubuntu-22.04 ]
+            python-version: '3.7'
     env: ${{ matrix.env }}
     steps:
       - name: Repository checkout
         uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
+      - name: Setup python
+        uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065
+        with:
+          python-version: ${{ matrix.python-version }}
       - name: Build check
         run: .github/workflows/build-test.sh

meson.build

@@ -1958,6 +1958,8 @@ endif
 
 conf.set10('HAVE_VMLINUX_H', use_provided_vmlinux_h or use_generated_vmlinux_h)
 
+conf.set10('ENABLE_SYSCTL_BPF', conf.get('HAVE_VMLINUX_H') == 1 and libbpf.version().version_compare('>= 0.7'))
+
 #####################################################################
 
 check_version_history_py   = files('tools/check-version-history.py')

src/basic/filesystem-sets.py

@@ -307,8 +307,7 @@ def generate_fs_in_group():
     print('        switch (fs_group) {')
 
     for name, _, *filesystems in FILESYSTEM_SETS:
-        magics = sorted(set(sum((NAME_TO_MAGIC[fs] for fs in filesystems),
-                                start=[])))
+        magics = sorted(set(sum((NAME_TO_MAGIC[fs] for fs in filesystems), [])))
         enum = 'FILESYSTEM_SET_' + name[1:].upper().replace('-', '_')
         print(f'        case {enum}:')
         opts = '\n                    || '.join(f'F_TYPE_EQUAL(st->f_type, {magic})'
@@ -355,7 +354,7 @@ def magic_defines():
 
 def check():
     kernel_magics = set(magic_defines())
-    our_magics = set(sum(NAME_TO_MAGIC.values(), start=[]))
+    our_magics = set(sum(NAME_TO_MAGIC.values(), []))
     extra = kernel_magics - our_magics
     if extra:
         sys.exit(f"kernel knows additional filesystem magics: {', '.join(sorted(extra))}")

src/network/bpf/sysctl-monitor/meson.build

@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: LGPL-2.1-or-later
 
-if conf.get('HAVE_VMLINUX_H') != 1
+if conf.get('ENABLE_SYSCTL_BPF') != 1
         subdir_done()
 endif
 

src/network/meson.build

@@ -140,7 +140,7 @@ networkctl_sources = files(
 networkd_network_gperf_gperf = files('networkd-network-gperf.gperf')
 networkd_netdev_gperf_gperf = files('netdev/netdev-gperf.gperf')
 
-if conf.get('HAVE_VMLINUX_H') == 1
+if conf.get('ENABLE_SYSCTL_BPF') == 1
         systemd_networkd_extract_sources += sysctl_monitor_skel_h
 endif
 

src/network/networkd-manager.c

@@ -646,7 +646,7 @@ int manager_new(Manager **ret, bool test_mode) {
                 .dhcp_server_persist_leases = DHCP_SERVER_PERSIST_LEASES_YES,
                 .serialization_fd = -EBADF,
                 .ip_forwarding = { -1, -1, },
-#if HAVE_VMLINUX_H
+#if ENABLE_SYSCTL_BPF
                 .cgroup_fd = -EBADF,
 #endif
         };

src/network/networkd-manager.h

@@ -117,7 +117,7 @@ typedef struct Manager {
 
         /* sysctl */
         int ip_forwarding[2];
-#if HAVE_VMLINUX_H
+#if ENABLE_SYSCTL_BPF
         Hashmap *sysctl_shadow;
         sd_event_source *sysctl_event_source;
         struct ring_buffer *sysctl_buffer;
@@ -148,7 +148,7 @@ int manager_set_timezone(Manager *m, const char *timezone);
 int manager_reload(Manager *m, sd_bus_message *message);
 
 static inline Hashmap** manager_get_sysctl_shadow(Manager *manager) {
-#if HAVE_VMLINUX_H
+#if ENABLE_SYSCTL_BPF
         return &ASSERT_PTR(manager)->sysctl_shadow;
 #else
         return NULL;

src/network/networkd-sysctl.c

@@ -26,7 +26,7 @@
 #include "string-util.h"
 #include "sysctl-util.h"
 
-#if HAVE_VMLINUX_H
+#if ENABLE_SYSCTL_BPF
 
 #include "bpf-link.h"
 #include "bpf/sysctl-monitor/sysctl-monitor-skel.h"

src/network/networkd-sysctl.h

@@ -22,7 +22,7 @@ typedef enum IPReversePathFilter {
         _IP_REVERSE_PATH_FILTER_INVALID = -EINVAL,
 } IPReversePathFilter;
 
-#if HAVE_VMLINUX_H
+#if ENABLE_SYSCTL_BPF
 int manager_install_sysctl_monitor(Manager *manager);
 void manager_remove_sysctl_monitor(Manager *manager);
 int link_clear_sysctl_shadows(Link *link);

src/oom/test-oomd-util.c

@@ -68,6 +68,8 @@ TEST(oomd_cgroup_kill) {
         /* Create another cgroup below this one for the pids we forked off. We need this to be managed
          * by the test so that pid1 doesn't delete it before we can read the xattrs. */
         ASSERT_NOT_NULL(subcgroup = path_join(cgroup, "oomdkilltest"));
+        /* Always start clean, in case of repeated runs and failures */
+        ASSERT_OK(cg_trim(subcgroup, /* delete_root */ true));
         ASSERT_OK(cg_create(subcgroup));
 
         /* If we don't have permissions to set xattrs we're likely in a userns or missing capabilities */
@@ -106,6 +108,8 @@ TEST(oomd_cgroup_kill) {
                 ASSERT_OK(cg_get_xattr(subcgroup, "user.oomd_kill", &v, /* ret_size= */ NULL));
                 ASSERT_STREQ(v, i == 0 ? "2" : "4");
         }
+
+        ASSERT_OK(cg_trim(subcgroup, /* delete_root */ true));
 }
 
 TEST(oomd_cgroup_context_acquire_and_insert) {

src/shared/seccomp-util.c

@@ -1,5 +1,9 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 
+/* This needs to be included before the seccomp headers, otherwise missing syscalls will be defined in this
+ * file and pass the ifdef, but they won't be defined in the seccomp headers so things like
+ * SCMP_SYS(fchmodat2) will resolve as empty and fail the build with older glibc/libseccomp. */
+#include <sys/syscall.h>
 #include <fcntl.h>
 #include <linux/seccomp.h>
 #include <sched.h>

src/test/test-bpf-token.c

@@ -7,7 +7,7 @@
 #include "tests.h"
 
 static int intro(void) {
-#if __LIBBPF_CURRENT_VERSION_GEQ(1, 5)
+#if defined(LIBBPF_MAJOR_VERSION) && (LIBBPF_MAJOR_VERSION > 1 || (LIBBPF_MAJOR_VERSION == 1 && LIBBPF_MINOR_VERSION >= 5))
         _cleanup_close_ int bpffs_fd = open("/sys/fs/bpf", O_RDONLY);
         if (bpffs_fd < 0)
                 return log_error_errno(errno, "Failed to open '/sys/fs/bpf': %m");

src/test/test-cgroup.c

@@ -51,10 +51,12 @@ TEST(cg_create) {
         _cleanup_free_ char *here = NULL;
         ASSERT_OK(cg_pid_get_path_shifted(0, NULL, &here));
 
-        _cleanup_free_ char *test_a = ASSERT_NOT_NULL(path_join(here, "/test-a")),
-                            *test_b = ASSERT_NOT_NULL(path_join(here, "/test-b")),
-                            *test_c = ASSERT_NOT_NULL(path_join(here, "/test-b/test-c")),
-                            *test_d = ASSERT_NOT_NULL(path_join(here, "/test-b/test-d"));
+        /* cg_* will use path_simplify(), so use it here too otherwise when running in a container at the
+         * root it asserts with "/test-b != //test-b" */
+        _cleanup_free_ char *test_a = ASSERT_NOT_NULL(path_simplify(path_join(here, "/test-a"))),
+                            *test_b = ASSERT_NOT_NULL(path_simplify(path_join(here, "/test-b"))),
+                            *test_c = ASSERT_NOT_NULL(path_simplify(path_join(here, "/test-b/test-c"))),
+                            *test_d = ASSERT_NOT_NULL(path_simplify(path_join(here, "/test-b/test-d")));
         char *path;
 
         log_info("Paths for test:\n%s\n%s", test_a, test_b);