[RFC PATCH 4/4] apparmor: differentiate between subjective and objective task credentials
Paul Moore
paul at paul-moore.com
Fri Feb 19 23:29:23 UTC 2021
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 <paul at paul-moore.com>
---
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;
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