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Subject[PATCH 6/7] exec: Move most of setup_new_exec into flush_old_exec

The current idiom for the callers is:

flush_old_exec(bprm);
set_personality(...);
setup_new_exec(bprm);

In 2010 Linus split flush_old_exec into flush_old_exec and
setup_new_exec. With the intention that setup_new_exec be what is
called after the processes new personality is set.

Move the code that doesn't depend upon the personality from
setup_new_exec into flush_old_exec. This is to facilitate future
changes by having as much code together in one function as possible.

Ref: 221af7f87b97 ("Split 'flush_old_exec' into two functions")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
fs/exec.c | 85 ++++++++++++++++++++++++++++---------------------------
1 file changed, 44 insertions(+), 41 deletions(-)

diff --git a/fs/exec.c b/fs/exec.c
index 8c3abafb9bb1..0eff20558735 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1359,39 +1359,7 @@ int flush_old_exec(struct linux_binprm * bprm)
* undergoing exec(2).
*/
do_close_on_exec(me->files);
- return 0;
-
-out_unlock:
- mutex_unlock(&me->signal->exec_update_mutex);
-out:
- return retval;
-}
-EXPORT_SYMBOL(flush_old_exec);
-
-void would_dump(struct linux_binprm *bprm, struct file *file)
-{
- struct inode *inode = file_inode(file);
- if (inode_permission(inode, MAY_READ) < 0) {
- struct user_namespace *old, *user_ns;
- bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
-
- /* Ensure mm->user_ns contains the executable */
- user_ns = old = bprm->mm->user_ns;
- while ((user_ns != &init_user_ns) &&
- !privileged_wrt_inode_uidgid(user_ns, inode))
- user_ns = user_ns->parent;

- if (old != user_ns) {
- bprm->mm->user_ns = get_user_ns(user_ns);
- put_user_ns(old);
- }
- }
-}
-EXPORT_SYMBOL(would_dump);
-
-void setup_new_exec(struct linux_binprm * bprm)
-{
- struct task_struct *me = current;
/*
* Once here, prepare_binrpm() will not be called any more, so
* the final state of setuid/setgid/fscaps can be merged into the
@@ -1414,8 +1382,6 @@ void setup_new_exec(struct linux_binprm * bprm)
bprm->rlim_stack.rlim_cur = _STK_LIM;
}

- arch_pick_mmap_layout(me->mm, &bprm->rlim_stack);
-
me->sas_ss_sp = me->sas_ss_size = 0;

/*
@@ -1430,16 +1396,9 @@ void setup_new_exec(struct linux_binprm * bprm)
else
set_dumpable(current->mm, SUID_DUMP_USER);

- arch_setup_new_exec();
perf_event_exec();
__set_task_comm(me, kbasename(bprm->filename), true);

- /* Set the new mm task size. We have to do that late because it may
- * depend on TIF_32BIT which is only updated in flush_thread() on
- * some architectures like powerpc
- */
- me->mm->task_size = TASK_SIZE;
-
/* An exec changes our domain. We are no longer part of the thread
group */
WRITE_ONCE(me->self_exec_id, me->self_exec_id + 1);
@@ -1467,6 +1426,50 @@ void setup_new_exec(struct linux_binprm * bprm)
* credentials; any time after this it may be unlocked.
*/
security_bprm_committed_creds(bprm);
+ return 0;
+
+out_unlock:
+ mutex_unlock(&me->signal->exec_update_mutex);
+out:
+ return retval;
+}
+EXPORT_SYMBOL(flush_old_exec);
+
+void would_dump(struct linux_binprm *bprm, struct file *file)
+{
+ struct inode *inode = file_inode(file);
+ if (inode_permission(inode, MAY_READ) < 0) {
+ struct user_namespace *old, *user_ns;
+ bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
+
+ /* Ensure mm->user_ns contains the executable */
+ user_ns = old = bprm->mm->user_ns;
+ while ((user_ns != &init_user_ns) &&
+ !privileged_wrt_inode_uidgid(user_ns, inode))
+ user_ns = user_ns->parent;
+
+ if (old != user_ns) {
+ bprm->mm->user_ns = get_user_ns(user_ns);
+ put_user_ns(old);
+ }
+ }
+}
+EXPORT_SYMBOL(would_dump);
+
+void setup_new_exec(struct linux_binprm * bprm)
+{
+ /* Setup things that can depend upon the personality */
+ struct task_struct *me = current;
+
+ arch_pick_mmap_layout(me->mm, &bprm->rlim_stack);
+
+ arch_setup_new_exec();
+
+ /* Set the new mm task size. We have to do that late because it may
+ * depend on TIF_32BIT which is only updated in flush_thread() on
+ * some architectures like powerpc
+ */
+ me->mm->task_size = TASK_SIZE;
mutex_unlock(&me->signal->exec_update_mutex);
mutex_unlock(&me->signal->cred_guard_mutex);
}
--
2.20.1
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