From 5b28255278dd7e594c8dde317c2498b7dcbf900d Mon Sep 17 00:00:00 2001 From: Davidlohr Bueso Date: Sun, 22 Feb 2015 18:20:09 -0800 Subject: [PATCH] audit: reduce mmap_sem hold for mm->exe_file The mm->exe_file is currently serialized with mmap_sem (shared) in order to both safely (1) read the file and (2) audit it via audit_log_d_path(). Good users will, on the other hand, make use of the more standard get_mm_exe_file(), requiring only holding the mmap_sem to read the value, and relying on reference counting to make sure that the exe file won't dissapear underneath us. Additionally, upon NULL return of get_mm_exe_file, we also call audit_log_format(ab, " exe=(null)"). Signed-off-by: Davidlohr Bueso [PM: tweaked subject line] Signed-off-by: Paul Moore --- kernel/audit.c | 22 ++++++++++++++-------- 1 file changed, 14 insertions(+), 8 deletions(-) diff --git a/kernel/audit.c b/kernel/audit.c index 684b51d612a3..52ee8eee0e07 100644 --- a/kernel/audit.c +++ b/kernel/audit.c @@ -43,6 +43,7 @@ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt +#include #include #include #include @@ -1851,15 +1852,20 @@ EXPORT_SYMBOL(audit_log_task_context); void audit_log_d_path_exe(struct audit_buffer *ab, struct mm_struct *mm) { - if (!mm) { - audit_log_format(ab, " exe=(null)"); - return; - } + struct file *exe_file; - down_read(&mm->mmap_sem); - if (mm->exe_file) - audit_log_d_path(ab, " exe=", &mm->exe_file->f_path); - up_read(&mm->mmap_sem); + if (!mm) + goto out_null; + + exe_file = get_mm_exe_file(mm); + if (!exe_file) + goto out_null; + + audit_log_d_path(ab, " exe=", &exe_file->f_path); + fput(exe_file); + return; +out_null: + audit_log_format(ab, " exe=(null)"); } void audit_log_task_info(struct audit_buffer *ab, struct task_struct *tsk)