78 lines
2.4 KiB
Diff
78 lines
2.4 KiB
Diff
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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Date: Wed, 11 Oct 2017 17:43:49 +0200
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Subject: apparmor: use a locallock instead preempt_disable()
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.1-rt3.tar.xz
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get_buffers() disables preemption which acts as a lock for the per-CPU
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variable. Since we can't disable preemption here on RT, a local_lock is
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lock is used in order to remain on the same CPU and not to have more
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than one user within the critical section.
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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security/apparmor/include/path.h | 19 ++++++++++++++++---
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security/apparmor/lsm.c | 2 +-
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2 files changed, 17 insertions(+), 4 deletions(-)
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--- a/security/apparmor/include/path.h
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+++ b/security/apparmor/include/path.h
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@@ -40,8 +40,10 @@ struct aa_buffers {
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#include <linux/percpu.h>
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#include <linux/preempt.h>
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+#include <linux/locallock.h>
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DECLARE_PER_CPU(struct aa_buffers, aa_buffers);
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+DECLARE_LOCAL_IRQ_LOCK(aa_buffers_lock);
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#define ASSIGN(FN, A, X, N) ((X) = FN(A, N))
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#define EVAL1(FN, A, X) ASSIGN(FN, A, X, 0) /*X = FN(0)*/
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@@ -51,7 +53,17 @@ DECLARE_PER_CPU(struct aa_buffers, aa_bu
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#define for_each_cpu_buffer(I) for ((I) = 0; (I) < MAX_PATH_BUFFERS; (I)++)
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-#ifdef CONFIG_DEBUG_PREEMPT
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+#ifdef CONFIG_PREEMPT_RT_BASE
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+static inline void AA_BUG_PREEMPT_ENABLED(const char *s)
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+{
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+ struct local_irq_lock *lv;
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+
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+ lv = this_cpu_ptr(&aa_buffers_lock);
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+ WARN_ONCE(lv->owner != current,
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+ "__get_buffer without aa_buffers_lock\n");
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+}
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+
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+#elif defined(CONFIG_DEBUG_PREEMPT)
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#define AA_BUG_PREEMPT_ENABLED(X) AA_BUG(preempt_count() <= 0, X)
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#else
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#define AA_BUG_PREEMPT_ENABLED(X) /* nop */
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@@ -67,14 +79,15 @@ DECLARE_PER_CPU(struct aa_buffers, aa_bu
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#define get_buffers(X...) \
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do { \
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- struct aa_buffers *__cpu_var = get_cpu_ptr(&aa_buffers); \
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+ struct aa_buffers *__cpu_var; \
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+ __cpu_var = get_locked_ptr(aa_buffers_lock, &aa_buffers); \
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__get_buffers(__cpu_var, X); \
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} while (0)
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#define put_buffers(X, Y...) \
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do { \
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__put_buffers(X, Y); \
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- put_cpu_ptr(&aa_buffers); \
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+ put_locked_ptr(aa_buffers_lock, &aa_buffers); \
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} while (0)
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#endif /* __AA_PATH_H */
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--- a/security/apparmor/lsm.c
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+++ b/security/apparmor/lsm.c
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@@ -45,7 +45,7 @@
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int apparmor_initialized;
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DEFINE_PER_CPU(struct aa_buffers, aa_buffers);
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-
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+DEFINE_LOCAL_IRQ_LOCK(aa_buffers_lock);
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/*
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* LSM hook functions
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