[PATCH v7 04/14] fork: provide a function for copying init_mm
From: Nadav Amit <hidden>
Date: 2018-12-05 08:52:51
Also in:
linux-integrity, lkml
Subsystem:
exec & binfmt api, elf, memory management - core, scheduler, the rest · Maintainers:
Kees Cook, Andrew Morton, David Hildenbrand, Ingo Molnar, Peter Zijlstra, Juri Lelli, Vincent Guittot, Linus Torvalds
Provide a function for copying init_mm. This function will be later used for setting a temporary mm. Cc: Andy Lutomirski <luto@kernel.org> Cc: Kees Cook <redacted> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Dave Hansen <redacted> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Tested-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Nadav Amit <redacted> --- include/linux/sched/task.h | 1 + kernel/fork.c | 24 ++++++++++++++++++------ 2 files changed, 19 insertions(+), 6 deletions(-)
diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h
index 108ede99e533..ac0a675678f5 100644
--- a/include/linux/sched/task.h
+++ b/include/linux/sched/task.h@@ -74,6 +74,7 @@ extern void exit_itimers(struct signal_struct *); extern long _do_fork(unsigned long, unsigned long, unsigned long, int __user *, int __user *, unsigned long); extern long do_fork(unsigned long, unsigned long, unsigned long, int __user *, int __user *); struct task_struct *fork_idle(int); +struct mm_struct *copy_init_mm(void); extern pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags); extern long kernel_wait4(pid_t, int __user *, int, struct rusage *);
diff --git a/kernel/fork.c b/kernel/fork.c
index 07cddff89c7b..01d3f5b39363 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c@@ -1297,13 +1297,20 @@ void mm_release(struct task_struct *tsk, struct mm_struct *mm) complete_vfork_done(tsk); } -/* - * Allocate a new mm structure and copy contents from the - * mm structure of the passed in task structure. +/** + * dup_mm() - duplicates an existing mm structure + * @tsk: the task_struct with which the new mm will be associated. + * @oldmm: the mm to duplicate. + * + * Allocates a new mm structure and copy contents from the provided + * @oldmm structure. + * + * Return: the duplicated mm or NULL on failure. */ -static struct mm_struct *dup_mm(struct task_struct *tsk) +static struct mm_struct *dup_mm(struct task_struct *tsk, + struct mm_struct *oldmm) { - struct mm_struct *mm, *oldmm = current->mm; + struct mm_struct *mm; int err; mm = allocate_mm();
@@ -1370,7 +1377,7 @@ static int copy_mm(unsigned long clone_flags, struct task_struct *tsk) } retval = -ENOMEM; - mm = dup_mm(tsk); + mm = dup_mm(tsk, current->mm); if (!mm) goto fail_nomem;
@@ -2176,6 +2183,11 @@ struct task_struct *fork_idle(int cpu) return task; } +struct mm_struct *copy_init_mm(void) +{ + return dup_mm(NULL, &init_mm); +} + /* * Ok, this is the main fork-routine. *
--
2.17.1