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apparmor: fix ptrace label match 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

  ptrace trace 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.

Fixes: 290f458a4f ("apparmor: allow ptrace checks to be finer grained than just capability")
Cc: Stable <stable@vger.kernel.org>
Reported-by: Matthew Garrett <mjg59@google.com>
Tested-by: Matthew Garrett <mjg59@google.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>
This commit is contained in:
John Johansen 2017-12-08 17:43:18 -08:00
parent c92a9a461d
commit 0dda0b3fb2
2 changed files with 35 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
security/apparmor/include/perms.h
View File

@ -133,6 +133,9 @@ extern struct aa_perms allperms;
#define xcheck_labels_profiles(L1, L2, FN, args...) \
xcheck_ns_labels((L1), (L2), xcheck_ns_profile_label, (FN), args)
#define xcheck_labels(L1, L2, P, FN1, FN2) \
xcheck(fn_for_each((L1), (P), (FN1)), fn_for_each((L2), (P), (FN2)))
void aa_perm_mask_to_str(char *str, const char *chrs, u32 mask);
void aa_audit_perm_names(struct audit_buffer *ab, const char **names, u32 mask);

53
security/apparmor/ipc.c
View File

@ -64,40 +64,48 @@ static void audit_ptrace_cb(struct audit_buffer *ab, void *va)
FLAGS_NONE, GFP_ATOMIC);
}
/* assumes check for PROFILE_MEDIATES is already done */
/* TODO: conditionals */
static int profile_ptrace_perm(struct aa_profile *profile,
struct aa_profile *peer, u32 request,
struct common_audit_data *sa)
struct aa_label *peer, u32 request,
struct common_audit_data *sa)
{
struct aa_perms perms = { };
/* need because of peer in cross check */
if (profile_unconfined(profile) ||
!PROFILE_MEDIATES(profile, AA_CLASS_PTRACE))
return 0;
aad(sa)->peer = &peer->label;
aa_profile_match_label(profile, &peer->label, AA_CLASS_PTRACE, request,
aad(sa)->peer = peer;
aa_profile_match_label(profile, peer, AA_CLASS_PTRACE, request,
&perms);
aa_apply_modes_to_perms(profile, &perms);
return aa_check_perms(profile, &perms, request, sa, audit_ptrace_cb);
}
static int cross_ptrace_perm(struct aa_profile *tracer,
struct aa_profile *tracee, u32 request,
struct common_audit_data *sa)
static int profile_tracee_perm(struct aa_profile *tracee,
struct aa_label *tracer, u32 request,
struct common_audit_data *sa)
{
if (profile_unconfined(tracee) || unconfined(tracer) ||
!PROFILE_MEDIATES(tracee, AA_CLASS_PTRACE))
return 0;
return profile_ptrace_perm(tracee, tracer, request, sa);
}
static int profile_tracer_perm(struct aa_profile *tracer,
struct aa_label *tracee, u32 request,
struct common_audit_data *sa)
{
if (profile_unconfined(tracer))
return 0;
if (PROFILE_MEDIATES(tracer, AA_CLASS_PTRACE))
return xcheck(profile_ptrace_perm(tracer, tracee, request, sa),
profile_ptrace_perm(tracee, tracer,
request << PTRACE_PERM_SHIFT,
sa));
/* policy uses the old style capability check for ptrace */
if (profile_unconfined(tracer) || tracer == tracee)
return profile_ptrace_perm(tracer, tracee, request, sa);
/* profile uses the old style capability check for ptrace */
if (&tracer->label == tracee)
return 0;
aad(sa)->label = &tracer->label;
aad(sa)->peer = &tracee->label;
aad(sa)->peer = tracee;
aad(sa)->request = 0;
aad(sa)->error = aa_capable(&tracer->label, CAP_SYS_PTRACE, 1);
@ -115,10 +123,13 @@ static int cross_ptrace_perm(struct aa_profile *tracer,
int aa_may_ptrace(struct aa_label *tracer, struct aa_label *tracee,
u32 request)
{
struct aa_profile *profile;
u32 xrequest = request << PTRACE_PERM_SHIFT;
DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_NONE, OP_PTRACE);
return xcheck_labels_profiles(tracer, tracee, cross_ptrace_perm,
request, &sa);
return xcheck_labels(tracer, tracee, profile,
profile_tracer_perm(profile, tracee, request, &sa),
profile_tracee_perm(profile, tracer, xrequest, &sa));
}