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[PATCH] Try to provide a bit of security for hardlinks to /dev entries.

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This commit is contained in:
mbuesch@freenet.de 2004-08-10 00:46:38 -07:00 committed by Greg KH
parent 16ddbbe10a
commit e2eef6d4dc
1 changed files with 38 additions and 8 deletions
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46
udev-remove.c
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@ -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);
}
}