tree-wide: always do dlopen() with RTLD_NOW + RTLD_NODELETE

Let's systematically use RTL_NOW|RLTD_NODELETE as flags passed to
dlopen(), across our codebase.

Various distros build with "-z now" anyway, hence it's weird to specify
RTLD_LAZY trying to override that (which it doesn't). Hence, let's
follow suit, and just do what everybody else does.

Also set RTLD_NODELETE, which is apparently what distros will probably
end up implying sooner or later anyway. Given that for pretty much all
our dlopen() calls we never call dlclose() anyway, let's just set this
everywhere too, to make things systematic.

This way, the flags we use by default match what distros such as fedora
do, there are no surprises, and read-only relocations can be a thing.

Fixes: #34537

8 files changed, 10 insertions, 11 deletions

diff --git a/src/basic/dlfcn-util.c b/src/basic/dlfcn-util.c
index 8022f55294..2ebb1463c2 100644
--- a/src/basic/dlfcn-util.c
+++ b/src/basic/dlfcn-util.c
@@ -44,7 +44,7 @@ int dlopen_many_sym_or_warn_sentinel(void **dlp, const char *filename, int log_l
         if (*dlp)
                 return 0; /* Already loaded */
 
-        dl = dlopen(filename, RTLD_LAZY);
+        dl = dlopen(filename, RTLD_NOW|RTLD_NODELETE);
         if (!dl)
                 return log_debug_errno(SYNTHETIC_ERRNO(EOPNOTSUPP),
                                        "%s is not installed: %s", filename, dlerror());
diff --git a/src/shared/bpf-dlopen.c b/src/shared/bpf-dlopen.c
index ca5060a102..87b13615c1 100644
--- a/src/shared/bpf-dlopen.c
+++ b/src/shared/bpf-dlopen.c
@@ -83,13 +83,13 @@ int dlopen_bpf(void) {
 
         DISABLE_WARNING_DEPRECATED_DECLARATIONS;
 
-        dl = dlopen("libbpf.so.1", RTLD_LAZY);
+        dl = dlopen("libbpf.so.1", RTLD_NOW|RTLD_NODELETE);
         if (!dl) {
                 /* libbpf < 1.0.0 (we rely on 0.1.0+) provide most symbols we care about, but
                  * unfortunately not all until 0.7.0. See bpf-compat.h for more details.
                  * Once we consider we can assume 0.7+ is present we can just use the same symbol
                  * list for both files, and when we assume 1.0+ is present we can remove this dlopen */
-                dl = dlopen("libbpf.so.0", RTLD_LAZY);
+                dl = dlopen("libbpf.so.0", RTLD_NOW|RTLD_NODELETE);
                 if (!dl)
                         return log_debug_errno(SYNTHETIC_ERRNO(EOPNOTSUPP),
                                                "neither libbpf.so.1 nor libbpf.so.0 are installed: %s", dlerror());
diff --git a/src/shared/idn-util.c b/src/shared/idn-util.c
index 7fa81677c9..c62f657491 100644
--- a/src/shared/idn-util.c
+++ b/src/shared/idn-util.c
@@ -52,11 +52,11 @@ int dlopen_idn(void) {
         if (idn_dl)
                 return 0; /* Already loaded */
 
-        dl = dlopen("libidn.so.12", RTLD_LAZY);
+        dl = dlopen("libidn.so.12", RTLD_NOW|RTLD_NODELETE);
         if (!dl) {
                 /* libidn broke ABI in 1.34, but not in a way we care about (a new field got added to an
                  * open-coded struct we do not use), hence support both versions. */
-                dl = dlopen("libidn.so.11", RTLD_LAZY);
+                dl = dlopen("libidn.so.11", RTLD_NOW|RTLD_NODELETE);
                 if (!dl)
                         return log_debug_errno(SYNTHETIC_ERRNO(EOPNOTSUPP),
                                                "libidn support is not installed: %s", dlerror());
@@ -64,7 +64,6 @@ int dlopen_idn(void) {
         } else
                 log_debug("Loaded 'libidn.so.12' via dlopen()");
 
-
         r = dlsym_many_or_warn(
                         dl,
                         LOG_DEBUG,
diff --git a/src/shared/tpm2-util.c b/src/shared/tpm2-util.c
index 723e6b4190..36a0f906da 100644
--- a/src/shared/tpm2-util.c
+++ b/src/shared/tpm2-util.c
@@ -724,7 +724,7 @@ int tpm2_context_new(const char *device, Tpm2Context **ret_context) {
                 if (!filename_is_valid(fn))
                         return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), "TPM2 driver name '%s' not valid, refusing.", driver);
 
-                context->tcti_dl = dlopen(fn, RTLD_NOW);
+                context->tcti_dl = dlopen(fn, RTLD_NOW|RTLD_NODELETE);
                 if (!context->tcti_dl)
                         return log_debug_errno(SYNTHETIC_ERRNO(ENOPKG), "Failed to load %s: %s", fn, dlerror());
 
diff --git a/src/shared/userdb.c b/src/shared/userdb.c
index c893876eaf..a35716c3d5 100644
--- a/src/shared/userdb.c
+++ b/src/shared/userdb.c
@@ -1443,7 +1443,7 @@ int userdb_block_nss_systemd(int b) {
 
         /* Note that we might be called from libnss_systemd.so.2 itself, but that should be fine, really. */
 
-        dl = dlopen(LIBDIR "/libnss_systemd.so.2", RTLD_LAZY|RTLD_NODELETE);
+        dl = dlopen(LIBDIR "/libnss_systemd.so.2", RTLD_NOW|RTLD_NODELETE);
         if (!dl) {
                 /* If the file isn't installed, don't complain loudly */
                 log_debug("Failed to dlopen(libnss_systemd.so.2), ignoring: %s", dlerror());
diff --git a/src/test/test-dlopen.c b/src/test/test-dlopen.c
index 9c315373b4..6704e936e7 100644
--- a/src/test/test-dlopen.c
+++ b/src/test/test-dlopen.c
@@ -10,7 +10,7 @@ int main(int argc, char **argv) {
         int i;
 
         for (i = 0; i < argc - 1; i++)
-                assert_se(handles[i] = dlopen(argv[i + 1], RTLD_NOW));
+                assert_se(handles[i] = dlopen(argv[i + 1], RTLD_NOW|RTLD_NODELETE));
 
         for (i--; i >= 0; i--)
                 assert_se(dlclose(handles[i]) == 0);
diff --git a/src/test/test-nss-hosts.c b/src/test/test-nss-hosts.c
index 6744d7068a..214fb217c8 100644
--- a/src/test/test-nss-hosts.c
+++ b/src/test/test-nss-hosts.c
@@ -380,7 +380,7 @@ static int test_one_module(const char *dir,
 
         log_info("======== %s ========", module);
 
-        _cleanup_(dlclosep) void *handle = nss_open_handle(dir, module, RTLD_LAZY|RTLD_NODELETE);
+        _cleanup_(dlclosep) void *handle = nss_open_handle(dir, module, RTLD_NOW|RTLD_NODELETE);
         if (!handle)
                 return -EINVAL;
 
diff --git a/src/test/test-nss-users.c b/src/test/test-nss-users.c
index 5178779d54..cba0f823b9 100644
--- a/src/test/test-nss-users.c
+++ b/src/test/test-nss-users.c
@@ -166,7 +166,7 @@ static int test_one_module(const char *dir,
 
         log_info("======== %s ========", module);
 
-        _cleanup_(dlclosep) void *handle = nss_open_handle(dir, module, RTLD_LAZY|RTLD_NODELETE);
+        _cleanup_(dlclosep) void *handle = nss_open_handle(dir, module, RTLD_NOW|RTLD_NODELETE);
         if (!handle)
                 return -EINVAL;