Commit 33fb4263 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'ucount-fixes-for-v5.16' of... 

Merge branch 'ucount-fixes-for-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

Pull ucount cleanups from Eric Biederman:
 "While working on the ucount fixes a for v5.15 a number of cleanups
  suggested themselves.

  Little things like not testing for NULL when a pointer can not be NULL
  and wrapping atomic_add_negative with a more descriptive name, so that
  people reading the code can more quickly understand what is going on"

* 'ucount-fixes-for-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
  ucounts: Use atomic_long_sub_return for clarity
  ucounts: Add get_ucounts_or_wrap for clarity
  ucounts: Remove unnecessary test for NULL ucount in get_ucounts
  ucounts: In set_cred_ucounts assume new->ucounts is non-NULL
parents a85373fe 32342701

kernel/cred.c

+2 −3
Original line number Original line Diff line number Diff line
@@ -676,14 +676,13 @@ int set_cred_ucounts(struct cred *new) 
	 * This optimization is needed because alloc_ucounts() uses locks

	 * This optimization is needed because alloc_ucounts() uses locks

	 * for table lookups.

	 * for table lookups.

	 */

	 */

	if (old_ucounts && old_ucounts->ns == new->user_ns && uid_eq(old_ucounts->uid, new->euid))

	if (old_ucounts->ns == new->user_ns && uid_eq(old_ucounts->uid, new->euid))

		return 0;

		return 0;





	if (!(new_ucounts = alloc_ucounts(new->user_ns, new->euid)))

	if (!(new_ucounts = alloc_ucounts(new->user_ns, new->euid)))

		return -EAGAIN;

		return -EAGAIN;





	new->ucounts = new_ucounts;

	new->ucounts = new_ucounts;

	if (old_ucounts)

	put_ucounts(old_ucounts);

	put_ucounts(old_ucounts);





	return 0;

	return 0;

kernel/ucount.c

+13 −7
Original line number Original line Diff line number Diff line
@@ -150,9 +150,15 @@ static void hlist_add_ucounts(struct ucounts *ucounts) 
	spin_unlock_irq(&ucounts_lock);

	spin_unlock_irq(&ucounts_lock);

}

}





static inline bool get_ucounts_or_wrap(struct ucounts *ucounts)

{

	/* Returns true on a successful get, false if the count wraps. */

	return !atomic_add_negative(1, &ucounts->count);

}



struct ucounts *get_ucounts(struct ucounts *ucounts)

struct ucounts *get_ucounts(struct ucounts *ucounts)

{

{

	if (ucounts && atomic_add_negative(1, &ucounts->count)) {

	if (!get_ucounts_or_wrap(ucounts)) {

		put_ucounts(ucounts);

		put_ucounts(ucounts);

		ucounts = NULL;

		ucounts = NULL;

	}

	}
@@ -163,7 +169,7 @@ struct ucounts *alloc_ucounts(struct user_namespace *ns, kuid_t uid) 
{

{

	struct hlist_head *hashent = ucounts_hashentry(ns, uid);

	struct hlist_head *hashent = ucounts_hashentry(ns, uid);

	struct ucounts *ucounts, *new;

	struct ucounts *ucounts, *new;

	long overflow;

	bool wrapped;





	spin_lock_irq(&ucounts_lock);

	spin_lock_irq(&ucounts_lock);

	ucounts = find_ucounts(ns, uid, hashent);

	ucounts = find_ucounts(ns, uid, hashent);
@@ -188,9 +194,9 @@ struct ucounts *alloc_ucounts(struct user_namespace *ns, kuid_t uid) 
			return new;

			return new;

		}

		}

	}

	}

	overflow = atomic_add_negative(1, &ucounts->count);

	wrapped = !get_ucounts_or_wrap(ucounts);

	spin_unlock_irq(&ucounts_lock);

	spin_unlock_irq(&ucounts_lock);

	if (overflow) {

	if (wrapped) {

		put_ucounts(ucounts);

		put_ucounts(ucounts);

		return NULL;

		return NULL;

	}

	}
@@ -276,7 +282,7 @@ bool dec_rlimit_ucounts(struct ucounts *ucounts, enum ucount_type type, long v) 
	struct ucounts *iter;

	struct ucounts *iter;

	long new = -1; /* Silence compiler warning */

	long new = -1; /* Silence compiler warning */

	for (iter = ucounts; iter; iter = iter->ns->ucounts) {

	for (iter = ucounts; iter; iter = iter->ns->ucounts) {

		long dec = atomic_long_add_return(-v, &iter->ucount[type]);

		long dec = atomic_long_sub_return(v, &iter->ucount[type]);

		WARN_ON_ONCE(dec < 0);

		WARN_ON_ONCE(dec < 0);

		if (iter == ucounts)

		if (iter == ucounts)

			new = dec;

			new = dec;
@@ -289,7 +295,7 @@ static void do_dec_rlimit_put_ucounts(struct ucounts *ucounts, 
{

{

	struct ucounts *iter, *next;

	struct ucounts *iter, *next;

	for (iter = ucounts; iter != last; iter = next) {

	for (iter = ucounts; iter != last; iter = next) {

		long dec = atomic_long_add_return(-1, &iter->ucount[type]);

		long dec = atomic_long_sub_return(1, &iter->ucount[type]);

		WARN_ON_ONCE(dec < 0);

		WARN_ON_ONCE(dec < 0);

		next = iter->ns->ucounts;

		next = iter->ns->ucounts;

		if (dec == 0)

		if (dec == 0)
@@ -326,7 +332,7 @@ long inc_rlimit_get_ucounts(struct ucounts *ucounts, enum ucount_type type) 
	}

	}

	return ret;

	return ret;

dec_unwind:

dec_unwind:

	dec = atomic_long_add_return(-1, &iter->ucount[type]);

	dec = atomic_long_sub_return(1, &iter->ucount[type]);

	WARN_ON_ONCE(dec < 0);

	WARN_ON_ONCE(dec < 0);

unwind:

unwind:

	do_dec_rlimit_put_ucounts(ucounts, iter, type);

	do_dec_rlimit_put_ucounts(ucounts, iter, type);