Commit 3dc6b1ce authored by John Johansen's avatar John Johansen
Browse files

apparmor: make signal label match work when matching stacked labels 



Given a label with a profile stack of
    A//&B or A//&C ...

A ptrace rule should be able to specify a generic trace pattern with
a rule like

    signal send A//&**,

however this is failing because while the correct label match routine
is called, it is being done post label decomposition so it is always
being done against a profile instead of the stacked label.

To fix this refactor the cross check to pass the full peer label in to
the label_match.

Signed-off-by: default avatarJohn Johansen <john.johansen@canonical.com>
parent 1d6583d9

security/apparmor/ipc.c

+12 −28
Original line number Diff line number Diff line
@@ -184,50 +184,34 @@ static void audit_signal_cb(struct audit_buffer *ab, void *va) 
			FLAGS_NONE, GFP_ATOMIC);

}



/* TODO: update to handle compound name&name2, conditionals */

static void profile_match_signal(struct aa_profile *profile, const char *label,

				 int signal, struct aa_perms *perms)

{

	unsigned int state;



	/* TODO: secondary cache check <profile, profile, perm> */

	state = aa_dfa_next(profile->policy.dfa,

			    profile->policy.start[AA_CLASS_SIGNAL],

			    signal);

	state = aa_dfa_match(profile->policy.dfa, state, label);

	aa_compute_perms(profile->policy.dfa, state, perms);

}



static int profile_signal_perm(struct aa_profile *profile,

			       struct aa_profile *peer, u32 request,

			       struct aa_label *peer, u32 request,

			       struct common_audit_data *sa)

{

	struct aa_perms perms;

	unsigned int state;



	if (profile_unconfined(profile) ||

	    !PROFILE_MEDIATES(profile, AA_CLASS_SIGNAL))

		return 0;



	aad(sa)->peer = &peer->label;

	profile_match_signal(profile, peer->base.hname, aad(sa)->signal,

			     &perms);

	aad(sa)->peer = peer;

	/* TODO: secondary cache check <profile, profile, perm> */

	state = aa_dfa_next(profile->policy.dfa,

			    profile->policy.start[AA_CLASS_SIGNAL],

			    aad(sa)->signal);

	aa_label_match(profile, peer, state, false, request, &perms);

	aa_apply_modes_to_perms(profile, &perms);

	return aa_check_perms(profile, &perms, request, sa, audit_signal_cb);

}



static int aa_signal_cross_perm(struct aa_profile *sender,

				struct aa_profile *target,

				struct common_audit_data *sa)

{

	return xcheck(profile_signal_perm(sender, target, MAY_WRITE, sa),

		      profile_signal_perm(target, sender, MAY_READ, sa));

}



int aa_may_signal(struct aa_label *sender, struct aa_label *target, int sig)

{

	struct aa_profile *profile;

	DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_NONE, OP_SIGNAL);



	aad(&sa)->signal = map_signal_num(sig);

	return xcheck_labels_profiles(sender, target, aa_signal_cross_perm,

				      &sa);

	return xcheck_labels(sender, target, profile,

			profile_signal_perm(profile, target, MAY_WRITE, &sa),

			profile_signal_perm(profile, sender, MAY_READ, &sa));

}

CRA Git | Maintained and supported by SUSTech CRA and CCSE