85 lines
2.5 KiB
Diff
85 lines
2.5 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/4.14/older/patches-4.14.15-rt13.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 | 21 +++++++++++++++++----
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security/apparmor/lsm.c | 2 +-
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2 files changed, 18 insertions(+), 5 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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@@ -39,9 +39,10 @@ struct aa_buffers {
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};
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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 COUNT_ARGS(X...) COUNT_ARGS_HELPER(, ##X, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
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#define COUNT_ARGS_HELPER(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, n, X...) n
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@@ -55,12 +56,24 @@ 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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+
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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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#endif
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+
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#define __get_buffer(N) ({ \
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struct aa_buffers *__cpu_var; \
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AA_BUG_PREEMPT_ENABLED("__get_buffer without preempt disabled"); \
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@@ -73,14 +86,14 @@ 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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- preempt_disable(); \
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+ local_lock(aa_buffers_lock); \
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__get_buffers(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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- preempt_enable(); \
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+ local_unlock(aa_buffers_lock); \
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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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@@ -44,7 +44,7 @@
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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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