apparmor: add per cpu work buffers to avoid allocating buffers at every hook

Signed-off-by: John Johansen <john.johansen@canonical.com>
This commit is contained in:
John Johansen 2017-01-16 00:43:10 -08:00
parent e3ea1ca59a
commit d4669f0b03
2 changed files with 103 additions and 1 deletions

View File

@ -29,4 +29,57 @@ enum path_flags {
int aa_path_name(const struct path *path, int flags, char **buffer,
const char **name, const char **info);
#define MAX_PATH_BUFFERS 2
/* Per cpu buffers used during mediation */
/* preallocated buffers to use during path lookups */
struct aa_buffers {
char *buf[MAX_PATH_BUFFERS];
};
#include <linux/percpu.h>
#include <linux/preempt.h>
DECLARE_PER_CPU(struct aa_buffers, aa_buffers);
#define COUNT_ARGS(X...) COUNT_ARGS_HELPER(, ##X, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
#define COUNT_ARGS_HELPER(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, n, X...) n
#define CONCAT(X, Y) X ## Y
#define CONCAT_AFTER(X, Y) CONCAT(X, Y)
#define ASSIGN(FN, X, N) ((X) = FN(N))
#define EVAL1(FN, X) ASSIGN(FN, X, 0) /*X = FN(0)*/
#define EVAL2(FN, X, Y...) do { ASSIGN(FN, X, 1); EVAL1(FN, Y); } while (0)
#define EVAL(FN, X...) CONCAT_AFTER(EVAL, COUNT_ARGS(X))(FN, X)
#define for_each_cpu_buffer(I) for ((I) = 0; (I) < MAX_PATH_BUFFERS; (I)++)
#ifdef CONFIG_DEBUG_PREEMPT
#define AA_BUG_PREEMPT_ENABLED(X) AA_BUG(preempt_count() <= 0, X)
#else
#define AA_BUG_PREEMPT_ENABLED(X) /* nop */
#endif
#define __get_buffer(N) ({ \
struct aa_buffers *__cpu_var; \
AA_BUG_PREEMPT_ENABLED("__get_buffer without preempt disabled"); \
__cpu_var = this_cpu_ptr(&aa_buffers); \
__cpu_var->buf[(N)]; })
#define __get_buffers(X...) EVAL(__get_buffer, X)
#define __put_buffers(X, Y...) ((void)&(X))
#define get_buffers(X...) \
do { \
preempt_disable(); \
__get_buffers(X); \
} while (0)
#define put_buffers(X, Y...) \
do { \
__put_buffers(X, Y); \
preempt_enable(); \
} while (0)
#endif /* __AA_PATH_H */

View File

@ -41,6 +41,9 @@
/* Flag indicating whether initialization completed */
int apparmor_initialized __initdata;
DEFINE_PER_CPU(struct aa_buffers, aa_buffers);
/*
* LSM hook functions
*/
@ -868,6 +871,43 @@ static int __init set_init_ctx(void)
return 0;
}
static void destroy_buffers(void)
{
u32 i, j;
for_each_possible_cpu(i) {
for_each_cpu_buffer(j) {
kfree(per_cpu(aa_buffers, i).buf[j]);
per_cpu(aa_buffers, i).buf[j] = NULL;
}
}
}
static int __init alloc_buffers(void)
{
u32 i, j;
for_each_possible_cpu(i) {
for_each_cpu_buffer(j) {
char *buffer;
if (cpu_to_node(i) > num_online_nodes())
/* fallback to kmalloc for offline nodes */
buffer = kmalloc(aa_g_path_max, GFP_KERNEL);
else
buffer = kmalloc_node(aa_g_path_max, GFP_KERNEL,
cpu_to_node(i));
if (!buffer) {
destroy_buffers();
return -ENOMEM;
}
per_cpu(aa_buffers, i).buf[j] = buffer;
}
}
return 0;
}
#ifdef CONFIG_SYSCTL
static int apparmor_dointvec(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos)
@ -937,11 +977,17 @@ static int __init apparmor_init(void)
}
error = alloc_buffers();
if (error) {
AA_ERROR("Unable to allocate work buffers\n");
goto buffers_out;
}
error = set_init_ctx();
if (error) {
AA_ERROR("Failed to set context on init task\n");
aa_free_root_ns();
goto alloc_out;
goto buffers_out;
}
security_add_hooks(apparmor_hooks, ARRAY_SIZE(apparmor_hooks));
@ -956,6 +1002,9 @@ static int __init apparmor_init(void)
return error;
buffers_out:
destroy_buffers();
alloc_out:
aa_destroy_aafs();
aa_teardown_dfa_engine();