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-rw-r--r--udev-remove.c46
1 files changed, 38 insertions, 8 deletions
diff --git a/udev-remove.c b/udev-remove.c
index 27ff5bc0a2..4f2cd479c0 100644
--- a/udev-remove.c
+++ b/udev-remove.c
@@ -65,6 +65,41 @@ static int delete_path(char *path)
return 0;
}
+/** Remove all permissions on the device node, before
+ * unlinking it. This fixes a security issue.
+ * If the user created a hard-link to the device node,
+ * he can't use it any longer, because he lost permission
+ * to do so.
+ */
+static int secure_unlink(const char *filename)
+{
+ int retval;
+
+ retval = chown(filename, 0, 0);
+ if (retval) {
+ dbg("chown(%s, 0, 0) failed with error '%s'",
+ filename, strerror(errno));
+ /* We continue nevertheless.
+ * I think it's very unlikely for chown
+ * to fail here, if the file exists.
+ */
+ }
+ retval = chmod(filename, 0000);
+ if (retval) {
+ dbg("chmod(%s, 0000) failed with error '%s'",
+ filename, strerror(errno));
+ /* We continue nevertheless. */
+ }
+ retval = unlink(filename);
+ if (errno == ENOENT)
+ retval = 0;
+ if (retval) {
+ dbg("unlink(%s) failed with error '%s'",
+ filename, strerror(errno));
+ }
+ return retval;
+}
+
static int delete_node(struct udevice *dev)
{
char filename[NAME_SIZE];
@@ -79,14 +114,9 @@ static int delete_node(struct udevice *dev)
strfieldcat(filename, dev->name);
info("removing device node '%s'", filename);
- retval = unlink(filename);
- if (errno == ENOENT)
- retval = 0;
- if (retval) {
- dbg("unlink(%s) failed with error '%s'",
- filename, strerror(errno));
+ retval = secure_unlink(filename);
+ if (retval)
return retval;
- }
/* remove partition nodes */
if (dev->partitions > 0) {
@@ -94,7 +124,7 @@ static int delete_node(struct udevice *dev)
for (i = 1; i <= dev->partitions; i++) {
strfieldcpy(partitionname, filename);
strintcat(partitionname, i);
- unlink(partitionname);
+ secure_unlink(partitionname);
}
}