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rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229588AbhBUM6M (ORCPT ); Sun, 21 Feb 2021 07:58:12 -0500 Received: from [50.53.41.238] (helo=[192.168.192.153]) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1lDoIi-0005iM-1K; Sun, 21 Feb 2021 12:57:28 +0000 Subject: Re: [RFC PATCH 4/4] apparmor: differentiate between subjective and objective task credentials To: Paul Moore , Casey Schaufler Cc: linux-security-module@vger.kernel.org, selinux@vger.kernel.org, linux-audit@redhat.com References: <161377712068.87807.12246856567527156637.stgit@sifl> <161377736385.87807.7033400948278183233.stgit@sifl> From: John Johansen Autocrypt: addr=john.johansen@canonical.com; prefer-encrypt=mutual; keydata= LS0tLS1CRUdJTiBQR1AgUFVCTElDIEtFWSBCTE9DSy0tLS0tCgptUUlOQkU1bXJQb0JFQURB azE5UHNnVmdCS2tJbW1SMmlzUFE2bzdLSmhUVEtqSmR3VmJrV1NuTm4rbzZVcDVrCm5LUDFm NDlFQlFsY2VXZzF5cC9Od2JSOGFkK2VTRU8vdW1hL0srUHFXdkJwdEtDOVNXRDk3Rkc0dUI0 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enAydDMKY0srcmh4VXFpc094OERaZnoxQm5rYW9DUkZidnZ2ays3TC9mb21QbnRHUGtxSmNp WUU4VEdIa1p3MWhPa3UrNApPb00yR0I1bkVEbGorMlRGL2pMUStFaXBYOVBrUEpZdnhmUmxD NmRLOFBLS2ZYOUtkZm1BSWNnSGZuVjFqU24rCjh5SDJkakJQdEtpcVcwSjY5YUlzeXg3aVYv MDNwYVBDakpoN1hxOXZBenlkTjVVL1VBPT0KPTZQL2IKLS0tLS1FTkQgUEdQIFBVQkxJQyBL RVkgQkxPQ0stLS0tLQo= Organization: Canonical Message-ID: <28174118-93d2-e7a5-50fb-004185354625@canonical.com> Date: Sun, 21 Feb 2021 04:57:26 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <161377736385.87807.7033400948278183233.stgit@sifl> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: selinux@vger.kernel.org On 2/19/21 3:29 PM, Paul Moore wrote: > With the split of the security_task_getsecid() into subjective and > objective variants it's time to update AppArmor to ensure it is > using the correct task creds. > > Signed-off-by: Paul Moore This has a couple problems, that I will work on addressing > --- > security/apparmor/domain.c | 2 +- > security/apparmor/include/cred.h | 19 ++++++++++++++++--- > security/apparmor/include/task.h | 3 ++- > security/apparmor/lsm.c | 23 +++++++++++++++-------- > security/apparmor/task.c | 23 ++++++++++++++++++++--- > 5 files changed, 54 insertions(+), 16 deletions(-) > > diff --git a/security/apparmor/domain.c b/security/apparmor/domain.c > index f919ebd042fd2..9ed00b8dcdf0c 100644 > --- a/security/apparmor/domain.c > +++ b/security/apparmor/domain.c > @@ -67,7 +67,7 @@ static int may_change_ptraced_domain(struct aa_label *to_label, > tracer = ptrace_parent(current); > if (tracer) > /* released below */ > - tracerl = aa_get_task_label(tracer); > + tracerl = aa_get_task_label_subj(tracer); > > /* not ptraced */ > if (!tracer || unconfined(tracerl)) > diff --git a/security/apparmor/include/cred.h b/security/apparmor/include/cred.h > index 0b9ae4804ef73..43c21ef5568ab 100644 > --- a/security/apparmor/include/cred.h > +++ b/security/apparmor/include/cred.h > @@ -64,14 +64,27 @@ static inline struct aa_label *aa_get_newest_cred_label(const struct cred *cred) > } > > /** > - * __aa_task_raw_label - retrieve another task's label > + * __aa_task_raw_label_subj - retrieve another task's subjective label > * @task: task to query (NOT NULL) > * > - * Returns: @task's label without incrementing its ref count > + * Returns: @task's subjective label without incrementing its ref count > * > * If @task != current needs to be called in RCU safe critical section > */ > -static inline struct aa_label *__aa_task_raw_label(struct task_struct *task) > +static inline struct aa_label *__aa_task_raw_label_subj(struct task_struct *task) > +{ > + return aa_cred_raw_label(rcu_dereference(task->cred)); > +} > + > +/** > + * __aa_task_raw_label_obj - retrieve another task's objective label > + * @task: task to query (NOT NULL) > + * > + * Returns: @task's objective label without incrementing its ref count > + * > + * If @task != current needs to be called in RCU safe critical section > + */ > +static inline struct aa_label *__aa_task_raw_label_obj(struct task_struct *task) > { > return aa_cred_raw_label(__task_cred(task)); > } > diff --git a/security/apparmor/include/task.h b/security/apparmor/include/task.h > index f13d12373b25e..27a2961558555 100644 > --- a/security/apparmor/include/task.h > +++ b/security/apparmor/include/task.h > @@ -33,7 +33,8 @@ int aa_replace_current_label(struct aa_label *label); > int aa_set_current_onexec(struct aa_label *label, bool stack); > int aa_set_current_hat(struct aa_label *label, u64 token); > int aa_restore_previous_label(u64 cookie); > -struct aa_label *aa_get_task_label(struct task_struct *task); > +struct aa_label *aa_get_task_label_subj(struct task_struct *task); > +struct aa_label *aa_get_task_label_obj(struct task_struct *task); > > /** > * aa_free_task_ctx - free a task_ctx > diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c > index 15e37b9132679..38430851675b9 100644 > --- a/security/apparmor/lsm.c > +++ b/security/apparmor/lsm.c > @@ -119,7 +119,7 @@ static int apparmor_ptrace_access_check(struct task_struct *child, > int error; > > tracer = __begin_current_label_crit_section(); > - tracee = aa_get_task_label(child); > + tracee = aa_get_task_label_obj(child); > error = aa_may_ptrace(tracer, tracee, > (mode & PTRACE_MODE_READ) ? AA_PTRACE_READ > : AA_PTRACE_TRACE); > @@ -135,7 +135,7 @@ static int apparmor_ptrace_traceme(struct task_struct *parent) > int error; > > tracee = __begin_current_label_crit_section(); > - tracer = aa_get_task_label(parent); > + tracer = aa_get_task_label_subj(parent); > error = aa_may_ptrace(tracer, tracee, AA_PTRACE_TRACE); > aa_put_label(tracer); > __end_current_label_crit_section(tracee); > @@ -719,9 +719,16 @@ static void apparmor_bprm_committed_creds(struct linux_binprm *bprm) > return; > } > > -static void apparmor_task_getsecid(struct task_struct *p, u32 *secid) > +static void apparmor_task_getsecid_subj(struct task_struct *p, u32 *secid) > { > - struct aa_label *label = aa_get_task_label(p); > + struct aa_label *label = aa_get_task_label_subj(p); > + *secid = label->secid; > + aa_put_label(label); > +} > + > +static void apparmor_task_getsecid_obj(struct task_struct *p, u32 *secid) > +{ > + struct aa_label *label = aa_get_task_label_obj(p); > *secid = label->secid; > aa_put_label(label); > } > @@ -750,7 +757,7 @@ static int apparmor_task_kill(struct task_struct *target, struct kernel_siginfo > * Dealing with USB IO specific behavior > */ > cl = aa_get_newest_cred_label(cred); > - tl = aa_get_task_label(target); > + tl = aa_get_task_label_obj(target); > error = aa_may_signal(cl, tl, sig); > aa_put_label(cl); > aa_put_label(tl); > @@ -758,7 +765,7 @@ static int apparmor_task_kill(struct task_struct *target, struct kernel_siginfo > } > > cl = __begin_current_label_crit_section(); > - tl = aa_get_task_label(target); > + tl = aa_get_task_label_obj(target); > error = aa_may_signal(cl, tl, sig); > aa_put_label(tl); > __end_current_label_crit_section(cl); > @@ -1243,8 +1250,8 @@ static struct security_hook_list apparmor_hooks[] __lsm_ro_after_init = { > > LSM_HOOK_INIT(task_free, apparmor_task_free), > LSM_HOOK_INIT(task_alloc, apparmor_task_alloc), > - LSM_HOOK_INIT(task_getsecid_subj, apparmor_task_getsecid), > - LSM_HOOK_INIT(task_getsecid_obj, apparmor_task_getsecid), > + LSM_HOOK_INIT(task_getsecid_subj, apparmor_task_getsecid_subj), > + LSM_HOOK_INIT(task_getsecid_obj, apparmor_task_getsecid_obj), > LSM_HOOK_INIT(task_setrlimit, apparmor_task_setrlimit), > LSM_HOOK_INIT(task_kill, apparmor_task_kill), > > diff --git a/security/apparmor/task.c b/security/apparmor/task.c > index d17130ee6795d..c03c8e3928055 100644 > --- a/security/apparmor/task.c > +++ b/security/apparmor/task.c > @@ -16,17 +16,34 @@ > #include "include/task.h" > > /** > - * aa_get_task_label - Get another task's label > + * aa_get_task_label_subj - Get another task's subjective label > * @task: task to query (NOT NULL) > * > * Returns: counted reference to @task's label > */ > -struct aa_label *aa_get_task_label(struct task_struct *task) > +struct aa_label *aa_get_task_label_subj(struct task_struct *task) > { > struct aa_label *p; > > rcu_read_lock(); > - p = aa_get_newest_label(__aa_task_raw_label(task)); > + p = aa_get_newest_label(__aa_task_raw_label_subj(task)); > + rcu_read_unlock(); > + > + return p; > +} > + > +/** > + * aa_get_task_label_obj - Get another task's objective label > + * @task: task to query (NOT NULL) > + * > + * Returns: counted reference to @task's label > + */ > +struct aa_label *aa_get_task_label_obj(struct task_struct *task) > +{ > + struct aa_label *p; > + > + rcu_read_lock(); > + p = aa_get_newest_label(__aa_task_raw_label_obj(task)); > rcu_read_unlock(); > > return p; >