From: Lennart Poettering <lennart@poettering.net>
Date: Fri, 23 Dec 2016 10:09:47 +0000 (+0100)
Subject: dissect: make sure to manually follow symlinks when mounting dissected image
X-Git-Tag: v233~134^2~5
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=2eedfd2d8b3441e8cf6dae4bdc9afaefbda19c39;p=thirdparty%2Fsystemd.git

dissect: make sure to manually follow symlinks when mounting dissected image

If the dissected image contains symlinks for the mount points we need we
need to make sure to follow this with chase_symlinks() so that we don't
leave the image.
---

diff --git a/src/shared/dissect-image.c b/src/shared/dissect-image.c
index 878cb008aa9..5fc2ce25f0e 100644
--- a/src/shared/dissect-image.c
+++ b/src/shared/dissect-image.c
@@ -28,6 +28,7 @@
 #include "blkid-util.h"
 #include "dissect-image.h"
 #include "fd-util.h"
+#include "fs-util.h"
 #include "gpt.h"
 #include "mount-util.h"
 #include "path-util.h"
@@ -35,6 +36,7 @@
 #include "stdio-util.h"
 #include "string-table.h"
 #include "string-util.h"
+#include "strv.h"
 #include "udev-util.h"
 
 static int probe_filesystem(const char *node, char **ret_fstype) {
@@ -624,7 +626,9 @@ static int mount_partition(
                 DissectImageFlags flags) {
 
         const char *p, *options = NULL, *node, *fstype;
+        _cleanup_free_ char *chased = NULL;
         bool rw;
+        int r;
 
         assert(m);
         assert(where);
@@ -641,9 +645,13 @@ static int mount_partition(
 
         rw = m->rw && !(flags & DISSECT_IMAGE_READ_ONLY);
 
-        if (directory)
-                p = strjoina(where, directory);
-        else
+        if (directory) {
+                r = chase_symlinks(directory, where, CHASE_PREFIX_ROOT, &chased);
+                if (r < 0)
+                        return r;
+
+                p = chased;
+        } else
                 p = where;
 
         /* If requested, turn on discard support. */
@@ -677,22 +685,23 @@ int dissected_image_mount(DissectedImage *m, const char *where, DissectImageFlag
                 return r;
 
         if (m->partitions[PARTITION_ESP].found) {
-                const char *mp, *x;
+                const char *mp;
 
                 /* Mount the ESP to /efi if it exists and is empty. If it doesn't exist, use /boot instead. */
 
-                mp = "/efi";
-                x = strjoina(where, mp);
-                r = dir_is_empty(x);
-                if (r == -ENOENT) {
-                        mp = "/boot";
-                        x = strjoina(where, mp);
-                        r = dir_is_empty(x);
-                }
-                if (r > 0) {
-                        r = mount_partition(m->partitions + PARTITION_ESP, where, mp, flags);
+                FOREACH_STRING(mp, "/efi", "/boot") {
+                        _cleanup_free_ char *p = NULL;
+
+                        r = chase_symlinks(mp, where, CHASE_PREFIX_ROOT, &p);
                         if (r < 0)
-                                return r;
+                                continue;
+
+                        r = dir_is_empty(p);
+                        if (r > 0) {
+                                r = mount_partition(m->partitions + PARTITION_ESP, where, mp, flags);
+                                if (r < 0)
+                                        return r;
+                        }
                 }
         }