| Message ID | 20170201090606.22422-6-john.johansen@canonical.com |
|---|---|
| State | New |
| Headers | show |
diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c index 2e5463d..70617e5 100644 --- a/security/apparmor/lsm.c +++ b/security/apparmor/lsm.c @@ -443,6 +443,9 @@ static int common_file_perm(const char *op, struct file *file, u32 mask) struct aa_label *label; int error = 0; + if (file->f_path.dentry == aa_null.dentry) + return -EACCES; + label = aa_begin_current_label(NO_UPDATE); error = aa_file_perm(op, label, file, mask); aa_end_current_label(label);
When an fd is disallowed from being inherited during exec, instead of closed it is duped to a special apparmor/.null file. This prevents the fd from being reused by another file in case the application expects the original file on a give fd (eg stdin/stdout etc). This results in a denial message like [32375.561535] audit: type=1400 audit(1478825963.441:358): apparmor="DENIED" operation="file_inherit" namespace="root//lxd-t_<var-lib-lxd>" profile="/sbin/dhclient" name="/dev/pts/1" pid=16795 comm="dhclient" requested_mask="wr" denied_mask="wr" fsuid=165536 ouid=165536 Further access to the fd is resultin in the rather useless denial message of [32375.566820] audit: type=1400 audit(1478825963.445:359): apparmor="DENIED" operation="file_perm" namespace="root//lxd-t_<var-lib-lxd>" profile="/sbin/dhclient" name="/apparmor/.null" pid=16795 comm="dhclient" requested_mask="w" denied_mask="w" fsuid=165536 ouid=0 since we have the original denial, the noisy and useless .null based denials can be skipped. BugLink: http://bugs.launchpad.net/bugs/1660836 Signed-off-by: John Johansen <john.johansen@canonical.com> --- security/apparmor/lsm.c | 3 +++ 1 file changed, 3 insertions(+)