[PATCH 2/4] audit: Enable cacheing of cmdline in audit_context
Rather then reading from userspace on every call,
cache the page in the audit_context and couple
to that objects life-cycle.
Change-Id: Ia0d432bc4aba8588840f0dc0026a1e9483e5b485
Signed-off-by: William Roberts <wroberts(a)tresys.com>
---
kernel/auditsc.c | 48 +++++++++++++++++++++++++++++++++++++-----------
1 file changed, 37 insertions(+), 11 deletions(-)
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 45fd3d0..27f8224 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -270,6 +270,7 @@ struct audit_context {
} mmap;
};
int fds[2];
+ char *cmdline;
#if AUDIT_DEBUG
int put_count;
@@ -1044,6 +1045,14 @@ static inline void audit_free_aux(struct audit_context *context)
}
}
+static inline void audit_cmdline_free(struct audit_context *ctx)
+{
+ if (!ctx->cmdline)
+ return;
+ free_page((unsigned long)ctx->cmdline);
+ ctx->cmdline = NULL;
+}
+
static inline void audit_zero_context(struct audit_context *context,
enum audit_state state)
{
@@ -1118,6 +1127,7 @@ static inline void audit_free_context(struct audit_context
*context)
audit_free_aux(context);
kfree(context->filterkey);
kfree(context->sockaddr);
+ audit_cmdline_free(context);
kfree(context);
context = previous;
} while (context);
@@ -1154,35 +1164,51 @@ error_path:
EXPORT_SYMBOL(audit_log_task_context);
-static void audit_log_add_cmdline(struct audit_buffer *ab,
+static char *audit_cmdline_get_page(struct audit_buffer *ab,
struct task_struct *tsk)
{
int len;
unsigned long page;
- char *msg = "(null)";
-
- audit_log_format(ab, " cmdline=");
/* Get the process cmdline */
page = __get_free_page(GFP_TEMPORARY);
if (!page) {
- audit_log_untrustedstring(ab, msg);
- return;
+ return NULL;
}
len = proc_pid_cmdline(tsk, (char *)page);
if (len <= 0) {
free_page(page);
- audit_log_untrustedstring(ab, msg);
- return;
+ return NULL;
}
/*
* Ensure NULL terminated! Application could
* could be using setproctitle(3).
*/
((char *)page)[len-1] = '\0';
- msg = (char *)page;
+
+ /* XXX: Re-alloc to something smaller then a page here? */
+ return (char *)page;
+}
+
+static void audit_log_cmdline(struct audit_buffer *ab, struct task_struct *tsk,
+ struct audit_context *context)
+{
+ char *msg = "(null)";
+
+ audit_log_format(ab, " cmdline=");
+
+ /* Already cached */
+ if (context->cmdline) {
+ msg = context->cmdline;
+ goto out;
+ }
+ /* Not cached yet */
+ context->cmdline = audit_cmdline_get_page(ab, tsk);
+ if (!context->cmdline)
+ goto out;
+ msg = context->cmdline;
+out:
audit_log_untrustedstring(ab, msg);
- free_page(page);
}
static void audit_log_task_info(struct audit_buffer *ab, struct task_struct *tsk)
@@ -1211,7 +1237,6 @@ static void audit_log_task_info(struct audit_buffer *ab, struct
task_struct *tsk
}
up_read(&mm->mmap_sem);
}
- audit_log_add_cmdline(ab, tsk);
audit_log_task_context(ab);
}
@@ -1679,6 +1704,7 @@ static void audit_log_exit(struct audit_context *context, struct
task_struct *ts
audit_log_task_info(ab, tsk);
+ audit_log_cmdline(ab, tsk, context);
audit_log_key(ab, context->filterkey);
audit_log_end(ab);
--
1.7.9.5