From 7f0f2caa082e7490c160b2c992a094116474a95f Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Fri, 4 Nov 2022 18:26:42 +0100
Subject: [PATCH] dissect: fix fsck

Since f7725647bb41c3398a867f139efe526efe8aa1b3 when dissecting a disk
image we operate with fds to the device nodes in question wherever we
can. This includes when we fork off fsck, where we pass a /proc/self/fd/
path as argument. This only works if we keep that fd open however and
disable O_CLOEXEC on the fd. Hence do so, and fix fsck this way.

(Without this, all fsck will fail, since the fd path is invalid)

(cherry picked from commit f8ab781223bcb0330ee4499b879a62e84fee313e)

Related: #2138081
---
 src/shared/dissect-image.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/src/shared/dissect-image.c b/src/shared/dissect-image.c
index 6a991c877a..7676636723 100644
--- a/src/shared/dissect-image.c
+++ b/src/shared/dissect-image.c
@@ -1309,11 +1309,11 @@ static int is_loop_device(const char *path) {
         return true;
 }
 
-static int run_fsck(const char *node, const char *fstype) {
+static int run_fsck(int node_fd, const char *fstype) {
         int r, exit_status;
         pid_t pid;
 
-        assert(node);
+        assert(node_fd >= 0);
         assert(fstype);
 
         r = fsck_exists_for_fstype(fstype);
@@ -1322,16 +1322,20 @@ static int run_fsck(const char *node, const char *fstype) {
                 return 0;
         }
         if (r == 0) {
-                log_debug("Not checking partition %s, as fsck for %s does not exist.", node, fstype);
+                log_debug("Not checking partition %s, as fsck for %s does not exist.", FORMAT_PROC_FD_PATH(node_fd), fstype);
                 return 0;
         }
 
-        r = safe_fork("(fsck)", FORK_RESET_SIGNALS|FORK_CLOSE_ALL_FDS|FORK_RLIMIT_NOFILE_SAFE|FORK_DEATHSIG|FORK_NULL_STDIO, &pid);
+        r = safe_fork_full(
+                        "(fsck)",
+                        &node_fd, 1, /* Leave the node fd open */
+                        FORK_RESET_SIGNALS|FORK_CLOSE_ALL_FDS|FORK_RLIMIT_NOFILE_SAFE|FORK_DEATHSIG|FORK_NULL_STDIO|FORK_CLOEXEC_OFF,
+                        &pid);
         if (r < 0)
                 return log_debug_errno(r, "Failed to fork off fsck: %m");
         if (r == 0) {
                 /* Child */
-                execl("/sbin/fsck", "/sbin/fsck", "-aT", node, NULL);
+                execl("/sbin/fsck", "/sbin/fsck", "-aT", FORMAT_PROC_FD_PATH(node_fd), NULL);
                 log_open();
                 log_debug_errno(errno, "Failed to execl() fsck: %m");
                 _exit(FSCK_OPERATIONAL_ERROR);
@@ -1421,7 +1425,7 @@ static int mount_partition(
         rw = m->rw && !(flags & DISSECT_IMAGE_MOUNT_READ_ONLY);
 
         if (FLAGS_SET(flags, DISSECT_IMAGE_FSCK) && rw) {
-                r = run_fsck(node, fstype);
+                r = run_fsck(m->mount_node_fd, fstype);
                 if (r < 0)
                         return r;
         }