From: Sebastian Andrzej Siewior Date: Wed, 11 Oct 2017 17:43:49 +0200 Subject: [PATCH 256/353] apparmor: use a locallock instead preempt_disable() Origin: https://git.kernel.org/cgit/linux/kernel/git/rt/linux-stable-rt.git/commit?id=becfde51f079b095ff4c0e80c735d8b52ad2cc24 get_buffers() disables preemption which acts as a lock for the per-CPU variable. Since we can't disable preemption here on RT, a local_lock is lock is used in order to remain on the same CPU and not to have more than one user within the critical section. Signed-off-by: Sebastian Andrzej Siewior --- security/apparmor/include/path.h | 19 ++++++++++++++++--- security/apparmor/lsm.c | 2 +- 2 files changed, 17 insertions(+), 4 deletions(-) diff --git a/security/apparmor/include/path.h b/security/apparmor/include/path.h index b6380c5f0097..12abfddb19c9 100644 --- a/security/apparmor/include/path.h +++ b/security/apparmor/include/path.h @@ -40,8 +40,10 @@ struct aa_buffers { #include #include +#include DECLARE_PER_CPU(struct aa_buffers, aa_buffers); +DECLARE_LOCAL_IRQ_LOCK(aa_buffers_lock); #define ASSIGN(FN, A, X, N) ((X) = FN(A, N)) #define EVAL1(FN, A, X) ASSIGN(FN, A, X, 0) /*X = FN(0)*/ @@ -51,7 +53,17 @@ DECLARE_PER_CPU(struct aa_buffers, aa_buffers); #define for_each_cpu_buffer(I) for ((I) = 0; (I) < MAX_PATH_BUFFERS; (I)++) -#ifdef CONFIG_DEBUG_PREEMPT +#ifdef CONFIG_PREEMPT_RT_BASE +static inline void AA_BUG_PREEMPT_ENABLED(const char *s) +{ + struct local_irq_lock *lv; + + lv = this_cpu_ptr(&aa_buffers_lock); + WARN_ONCE(lv->owner != current, + "__get_buffer without aa_buffers_lock\n"); +} + +#elif defined(CONFIG_DEBUG_PREEMPT) #define AA_BUG_PREEMPT_ENABLED(X) AA_BUG(preempt_count() <= 0, X) #else #define AA_BUG_PREEMPT_ENABLED(X) /* nop */ @@ -67,14 +79,15 @@ DECLARE_PER_CPU(struct aa_buffers, aa_buffers); #define get_buffers(X...) \ do { \ - struct aa_buffers *__cpu_var = get_cpu_ptr(&aa_buffers); \ + struct aa_buffers *__cpu_var; \ + __cpu_var = get_locked_ptr(aa_buffers_lock, &aa_buffers); \ __get_buffers(__cpu_var, X); \ } while (0) #define put_buffers(X, Y...) \ do { \ __put_buffers(X, Y); \ - put_cpu_ptr(&aa_buffers); \ + put_locked_ptr(aa_buffers_lock, &aa_buffers); \ } while (0) #endif /* __AA_PATH_H */ diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c index 898752b818dc..690c8fccd0a0 100644 --- a/security/apparmor/lsm.c +++ b/security/apparmor/lsm.c @@ -45,7 +45,7 @@ int apparmor_initialized; DEFINE_PER_CPU(struct aa_buffers, aa_buffers); - +DEFINE_LOCAL_IRQ_LOCK(aa_buffers_lock); /* * LSM hook functions