This is a note to let you know that I've just added the patch titled

apparmor: fix ptrace label match when matching stacked labels

to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: apparmor-fix-ptrace-label-match-when-matching-stacked-labels.patch and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From 0dda0b3fb255048a221f736c8a2a24c674da8bf3 Mon Sep 17 00:00:00 2001

From: John Johansen john.johansen@canonical.com Date: Fri, 8 Dec 2017 17:43:18 -0800 Subject: apparmor: fix ptrace label match when matching stacked labels

From: John Johansen john.johansen@canonical.com

commit 0dda0b3fb255048a221f736c8a2a24c674da8bf3 upstream.

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: 290f458a4f16 ("apparmor: allow ptrace checks to be finer grained than just capability") Reported-by: Matthew Garrett mjg59@google.com Tested-by: Matthew Garrett mjg59@google.com Signed-off-by: John Johansen john.johansen@canonical.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- security/apparmor/include/perms.h | 3 ++ security/apparmor/ipc.c | 53 ++++++++++++++++++++++---------------- 2 files changed, 35 insertions(+), 21 deletions(-)

--- a/security/apparmor/include/perms.h +++ b/security/apparmor/include/perms.h @@ -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); --- a/security/apparmor/ipc.c +++ b/security/apparmor/ipc.c @@ -64,40 +64,48 @@ static void audit_ptrace_cb(struct audit 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_p 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)); }

Patches currently in stable-queue which might be from john.johansen@canonical.com are

queue-4.14/apparmor-fix-ptrace-label-match-when-matching-stacked-labels.patch