Commit c923a8e7 authored by Eric W. Biederman's avatar Eric W. Biederman
Browse files

ucounts: Move RLIMIT_NPROC handling after set_user 

During set*id() which cred->ucounts to charge the the current process
to is not known until after set_cred_ucounts.  So move the
RLIMIT_NPROC checking into a new helper flag_nproc_exceeded and call
flag_nproc_exceeded after set_cred_ucounts.

This is very much an arbitrary subset of the places where we currently
change the RLIMIT_NPROC accounting, designed to preserve the existing
logic.

Fixing the existing logic will be the subject of another series of
changes.

Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20220216155832.680775-4-ebiederm@xmission.com


Fixes: 21d1c5e3 ("Reimplement RLIMIT_NPROC on top of ucounts")
Signed-off-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
parent a55d0729

kernel/sys.c

+14 −5
Original line number Diff line number Diff line
@@ -472,6 +472,16 @@ static int set_user(struct cred *new) 
	if (!new_user)

		return -EAGAIN;



	free_uid(new->user);

	new->user = new_user;

	return 0;

}



static void flag_nproc_exceeded(struct cred *new)

{

	if (new->ucounts == current_ucounts())

		return;



	/*

	 * 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
@@ -480,14 +490,10 @@ static int set_user(struct cred *new) 
	 * failure to the execve() stage.

	 */

	if (is_ucounts_overlimit(new->ucounts, UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC)) &&

			new_user != INIT_USER)

			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;

}



/*
@@ -562,6 +568,7 @@ long __sys_setreuid(uid_t ruid, uid_t euid) 
	if (retval < 0)

		goto error;



	flag_nproc_exceeded(new);

	return commit_creds(new);



error:
@@ -624,6 +631,7 @@ long __sys_setuid(uid_t uid) 
	if (retval < 0)

		goto error;



	flag_nproc_exceeded(new);

	return commit_creds(new);



error:
@@ -703,6 +711,7 @@ long __sys_setresuid(uid_t ruid, uid_t euid, uid_t suid) 
	if (retval < 0)

		goto error;



	flag_nproc_exceeded(new);

	return commit_creds(new);



error: