core/exec-invoke: negative errno needs to be passed to report_errno_and_exit()

Hence, we cannot pass errno as is to report_errno_and_exit().

This splits out bpffs_helper(), which returns negative errno on failure,
and 0 on success. And make the returned value passed to report_errno_and_exit().

Follow-up for #36134.

diff --git a/src/core/exec-invoke.c b/src/core/exec-invoke.c
index 6058553aac8eb6fe188b82ab46454551af8235d9..dcef723b46ceb722dd1658d03cd5df5adb4196de 100644 (file)
--- a/src/core/exec-invoke.c
+++ b/src/core/exec-invoke.c
@@ -2270,20 +2270,54 @@ static int setup_private_users_child(int unshare_ready_fd, const char *uid_map,
         return 0;
 }
 
+static int bpffs_helper(const ExecContext *c, int socket_fd) {
+        assert(c);
+        assert(socket_fd >= 0);
+
+        _cleanup_close_ int fs_fd = receive_one_fd(socket_fd, /* flags = */ 0);
+        if (fs_fd < 0)
+                return log_debug_errno(fs_fd, "Failed to receive file descriptor from parent: %m");
+
+        char number[STRLEN("0x") + sizeof(c->bpf_delegate_commands) * 2 + 1];
+        xsprintf(number, "0x%"PRIx64, c->bpf_delegate_commands);
+        if (fsconfig(fs_fd, FSCONFIG_SET_STRING, "delegate_cmds", number, /* aux = */ 0) < 0)
+                return log_debug_errno(errno, "Failed to FSCONFIG_SET_STRING: %m");
+
+        xsprintf(number, "0x%"PRIx64, c->bpf_delegate_maps);
+        if (fsconfig(fs_fd, FSCONFIG_SET_STRING, "delegate_maps", number, /* aux = */ 0) < 0)
+                return log_debug_errno(errno, "Failed to FSCONFIG_SET_STRING: %m");
+
+        xsprintf(number, "0x%"PRIx64, c->bpf_delegate_programs);
+        if (fsconfig(fs_fd, FSCONFIG_SET_STRING, "delegate_progs", number, /* aux = */ 0) < 0)
+                return log_debug_errno(errno, "Failed to FSCONFIG_SET_STRING: %m");
+
+        xsprintf(number, "0x%"PRIx64, c->bpf_delegate_attachments);
+        if (fsconfig(fs_fd, FSCONFIG_SET_STRING, "delegate_attachs", number, /* aux = */ 0) < 0)
+                return log_debug_errno(errno, "Failed to FSCONFIG_SET_STRING: %m");
+
+        if (fsconfig(fs_fd, FSCONFIG_CMD_CREATE, /* key = */ NULL, /* value = */ NULL, /* aux = */ 0) < 0)
+                return log_debug_errno(errno, "Failed to create bpffs superblock: %m");
+
+        if (write(socket_fd, (uint8_t[1]) {}, 1) < 0)
+                return log_debug_errno(errno, "Failed to send data to child: %m");
+
+        return 0;
+}
+
 static int bpffs_prepare(
                 const ExecContext *c,
                 PidRef *ret_pid,
                 int *ret_sock_fd,
                 int *ret_errno_pipe) {
 
-        _cleanup_close_pair_ int socket_fds[2] = EBADF_PAIR, bpffs_errno_pipe[2] = EBADF_PAIR;
+        _cleanup_close_pair_ int socket_fds[2] = EBADF_PAIR, errno_pipe[2] = EBADF_PAIR;
         int r;
 
         assert(ret_sock_fd);
         assert(ret_pid);
         assert(ret_errno_pipe);
 
-        r = pipe2(bpffs_errno_pipe, O_CLOEXEC|O_NONBLOCK);
+        r = pipe2(errno_pipe, O_CLOEXEC|O_NONBLOCK);
         if (r < 0)
                 return log_debug_errno(errno, "Failed to create pipe: %m");
 
@@ -2295,67 +2329,13 @@ static int bpffs_prepare(
         if (r < 0)
                 return log_debug_errno(r, "Failed to fork bpffs privileged helper: %m");
         if (r == 0) {
-                _cleanup_close_ int fs_fd = -EBADF;
-                char number[STRLEN("0x") + sizeof(c->bpf_delegate_commands) * 2 + 1];
-
-                bpffs_errno_pipe[0] = safe_close(bpffs_errno_pipe[0]);
+                errno_pipe[0] = safe_close(errno_pipe[0]);
                 socket_fds[0] = safe_close(socket_fds[0]);
-
-                fs_fd = receive_one_fd(socket_fds[1], /* flags = */ 0);
-                if (fs_fd < 0) {
-                        log_debug_errno(fs_fd, "Failed to receive file descriptor from parent: %m");
-                        report_errno_and_exit(bpffs_errno_pipe[1], fs_fd);
-                }
-
-                xsprintf(number, "0x%"PRIx64, c->bpf_delegate_commands);
-
-                r = fsconfig(fs_fd, FSCONFIG_SET_STRING, "delegate_cmds", number, /* aux = */ 0);
-                if (r < 0) {
-                        log_debug_errno(errno, "Failed to FSCONFIG_SET_STRING: %m");
-                        report_errno_and_exit(bpffs_errno_pipe[1], errno);
-                }
-
-                xsprintf(number, "0x%"PRIx64, c->bpf_delegate_maps);
-
-                r = fsconfig(fs_fd, FSCONFIG_SET_STRING, "delegate_maps", number, /* aux = */ 0);
-                if (r < 0) {
-                        log_debug_errno(errno, "Failed to FSCONFIG_SET_STRING: %m");
-                        report_errno_and_exit(bpffs_errno_pipe[1], errno);
-                }
-
-                xsprintf(number, "0x%"PRIx64, c->bpf_delegate_programs);
-
-                r = fsconfig(fs_fd, FSCONFIG_SET_STRING, "delegate_progs", number, /* aux = */ 0);
-                if (r < 0) {
-                        log_debug_errno(errno, "Failed to FSCONFIG_SET_STRING: %m");
-                        report_errno_and_exit(bpffs_errno_pipe[1], errno);
-                }
-
-                xsprintf(number, "0x%"PRIx64, c->bpf_delegate_attachments);
-
-                r = fsconfig(fs_fd, FSCONFIG_SET_STRING, "delegate_attachs", number, /* aux = */ 0);
-                if (r < 0) {
-                        log_debug_errno(errno, "Failed to FSCONFIG_SET_STRING: %m");
-                        report_errno_and_exit(bpffs_errno_pipe[1], errno);
-                }
-
-                r = fsconfig(fs_fd, FSCONFIG_CMD_CREATE, /* key = */ NULL, /* value = */ NULL, /* aux = */ 0);
-                if (r < 0) {
-                        log_debug_errno(errno, "Failed to create bpffs superblock: %m");
-                        report_errno_and_exit(bpffs_errno_pipe[1], errno);
-                }
-
-                if (write(socket_fds[1], (uint8_t[1]) {}, 1) < 0) {
-                        log_debug_errno(errno, "Failed to send data to child: %m");
-                        report_errno_and_exit(bpffs_errno_pipe[1], errno);
-                }
-
-                _exit(EXIT_SUCCESS);
+                report_errno_and_exit(errno_pipe[1], bpffs_helper(c, socket_fds[1]));
         }
 
         *ret_sock_fd = TAKE_FD(socket_fds[0]);
-        *ret_errno_pipe = TAKE_FD(bpffs_errno_pipe[0]);
-
+        *ret_errno_pipe = TAKE_FD(errno_pipe[0]);
         return 0;
 }