From 537f7ccb396804c6d0057b93ba8eb104ba44f851 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Mon, 8 Aug 2016 14:37:37 -0500 Subject: mntns: Add a limit on the number of mount namespaces. v2: Fixed the very obvious lack of setting ucounts on struct mnt_ns reported by Andrei Vagin, and the kbuild test report. Reported-by: Andrei Vagin Acked-by: Kees Cook Signed-off-by: "Eric W. Biederman" --- fs/mount.h | 1 + fs/namespace.c | 22 +++++++++++++++++++++- 2 files changed, 22 insertions(+), 1 deletion(-) (limited to 'fs') diff --git a/fs/mount.h b/fs/mount.h index 14db05d424f7..e037981d8351 100644 --- a/fs/mount.h +++ b/fs/mount.h @@ -10,6 +10,7 @@ struct mnt_namespace { struct mount * root; struct list_head list; struct user_namespace *user_ns; + struct ucounts *ucounts; u64 seq; /* Sequence number to prevent loops */ wait_queue_head_t poll; u64 event; diff --git a/fs/namespace.c b/fs/namespace.c index 7bb2cda3bfef..491b8f3e4c9a 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -2719,9 +2719,20 @@ dput_out: return retval; } +static struct ucounts *inc_mnt_namespaces(struct user_namespace *ns) +{ + return inc_ucount(ns, current_euid(), UCOUNT_MNT_NAMESPACES); +} + +static void dec_mnt_namespaces(struct ucounts *ucounts) +{ + dec_ucount(ucounts, UCOUNT_MNT_NAMESPACES); +} + static void free_mnt_ns(struct mnt_namespace *ns) { ns_free_inum(&ns->ns); + dec_mnt_namespaces(ns->ucounts); put_user_ns(ns->user_ns); kfree(ns); } @@ -2738,14 +2749,22 @@ static atomic64_t mnt_ns_seq = ATOMIC64_INIT(1); static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns) { struct mnt_namespace *new_ns; + struct ucounts *ucounts; int ret; + ucounts = inc_mnt_namespaces(user_ns); + if (!ucounts) + return ERR_PTR(-ENFILE); + new_ns = kmalloc(sizeof(struct mnt_namespace), GFP_KERNEL); - if (!new_ns) + if (!new_ns) { + dec_mnt_namespaces(ucounts); return ERR_PTR(-ENOMEM); + } ret = ns_alloc_inum(&new_ns->ns); if (ret) { kfree(new_ns); + dec_mnt_namespaces(ucounts); return ERR_PTR(ret); } new_ns->ns.ops = &mntns_operations; @@ -2756,6 +2775,7 @@ static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns) init_waitqueue_head(&new_ns->poll); new_ns->event = 0; new_ns->user_ns = get_user_ns(user_ns); + new_ns->ucounts = ucounts; return new_ns; } -- cgit