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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: John Johansen <john.johansen@canonical.com>
This commit is contained in:
John Johansen 2017-12-12 01:02:13 -08:00
parent 1d6583d9c6
commit 3dc6b1ce68
1 changed files with 12 additions and 28 deletions
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40
security/apparmor/ipc.c
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@ -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));
}