[RFC PATCH v2 8/8] Move RLIMIT_NPROC check to the place where we increment the counter

[Alexey Gladkov]

After calling set_user(), we always have to call commit_creds() to apply
new credentials upon the current task. There is no need to separate
limit check and counter incrementing.

Signed-off-by: Alexey Gladkov <gladkov.ale...@gmail.com>
---
 kernel/cred.c | 22 +++++++++++++++++-----
 kernel/sys.c  | 13 -------------
 2 files changed, 17 insertions(+), 18 deletions(-)

diff --git a/kernel/cred.c b/kernel/cred.c
index 89a945571533..770447b4f4de 100644
--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -488,14 +488,26 @@ int commit_creds(struct cred *new)
        if (!gid_eq(new->fsgid, old->fsgid))
                key_fsgid_changed(new);
 
-       /* do it
-        * RLIMIT_NPROC limits on user->processes have already been checked
-        * in set_user().
-        */
        alter_cred_subscribers(new, 2);
        if (new->user != old->user || new->user_ns != old->user_ns) {
+               bool overlimit;
+
                set_cred_ucounts(new, new->user_ns, new->euid);
-               inc_rlimit_ucounts(new->ucounts, UCOUNT_RLIMIT_NPROC, 1);
+
+               overlimit = inc_rlimit_ucounts_and_test(new->ucounts, 
UCOUNT_RLIMIT_NPROC,
+                               1, rlimit(RLIMIT_NPROC));
+
+               /*
+                * We don't fail in case of NPROC limit excess here because too 
many
+                * poorly written programs don't check set*uid() return code, 
assuming
+                * it never fails if called by root.  We may still enforce 
NPROC limit
+                * for programs doing set*uid()+execve() by harmlessly 
deferring the
+                * failure to the execve() stage.
+                */
+               if (overlimit && new->user != INIT_USER)
+                       current->flags |= PF_NPROC_EXCEEDED;
+               else
+                       current->flags &= ~PF_NPROC_EXCEEDED;
        }
        rcu_assign_pointer(task->real_cred, new);
        rcu_assign_pointer(task->cred, new);
diff --git a/kernel/sys.c b/kernel/sys.c
index c2734ab9474e..180c4e06064f 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -467,19 +467,6 @@ static int set_user(struct cred *new)
        if (!new_user)
                return -EAGAIN;
 
-       /*
-        * We don't fail in case of NPROC limit excess here because too many
-        * poorly written programs don't check set*uid() return code, assuming
-        * it never fails if called by root.  We may still enforce NPROC limit
-        * for programs doing set*uid()+execve() by harmlessly deferring the
-        * failure to the execve() stage.
-        */
-       if (is_ucounts_overlimit(new->ucounts, UCOUNT_RLIMIT_NPROC, 
rlimit(RLIMIT_NPROC)) &&
-                       new_user != INIT_USER)
-               current->flags |= PF_NPROC_EXCEEDED;
-       else
-               current->flags &= ~PF_NPROC_EXCEEDED;
-
        free_uid(new->user);
        new->user = new_user;
        return 0;
-- 
2.29.2