From a636b702ed1805e988ad3d8ff8b52c060f8b341c Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Thu, 21 Mar 2013 18:13:15 -0700 Subject: ipc: Restrict mounting the mqueue filesystem Only allow mounting the mqueue filesystem if the caller has CAP_SYS_ADMIN rights over the ipc namespace. The principle here is if you create or have capabilities over it you can mount it, otherwise you get to live with what other people have mounted. This information is not particularly sensitive and mqueue essentially only reports which posix messages queues exist. Still when creating a restricted environment for an application to live any extra information may be of use to someone with sufficient creativity. The historical if imperfect way this information has been restricted has been not to allow mounts and restricting this to ipc namespace creators maintains the spirit of the historical restriction. Cc: stable@vger.kernel.org Acked-by: Serge Hallyn Signed-off-by: "Eric W. Biederman" --- ipc/mqueue.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) (limited to 'ipc') diff --git a/ipc/mqueue.c b/ipc/mqueue.c index e5c4f609f22c..c4ae32ec6c6b 100644 --- a/ipc/mqueue.c +++ b/ipc/mqueue.c @@ -330,8 +330,16 @@ static struct dentry *mqueue_mount(struct file_system_type *fs_type, int flags, const char *dev_name, void *data) { - if (!(flags & MS_KERNMOUNT)) - data = current->nsproxy->ipc_ns; + if (!(flags & MS_KERNMOUNT)) { + struct ipc_namespace *ns = current->nsproxy->ipc_ns; + /* Don't allow mounting unless the caller has CAP_SYS_ADMIN + * over the ipc namespace. + */ + if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN)) + return ERR_PTR(-EPERM); + + data = ns; + } return mount_ns(fs_type, flags, data, mqueue_fill_super); } -- cgit v1.2.3 From 2dc958fa2fe6987e7ab106bd97029a09a82fcd8d Mon Sep 17 00:00:00 2001 From: Stanislav Kinsbursky Date: Mon, 1 Apr 2013 11:40:51 +0400 Subject: ipc: set msg back to -EAGAIN if copy wasn't performed Make sure that msg pointer is set back to error value in case of MSG_COPY flag is set and desired message to copy wasn't found. This garantees that msg is either a error pointer or a copy address. Otherwise the last message in queue will be freed without unlinking from the queue (which leads to memory corruption) and the dummy allocated copy won't be released. Signed-off-by: Stanislav Kinsbursky Signed-off-by: Linus Torvalds --- ipc/msg.c | 1 + 1 file changed, 1 insertion(+) (limited to 'ipc') diff --git a/ipc/msg.c b/ipc/msg.c index 31cd1bf6af27..fede1d06ef30 100644 --- a/ipc/msg.c +++ b/ipc/msg.c @@ -872,6 +872,7 @@ long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, goto out_unlock; break; } + msg = ERR_PTR(-EAGAIN); } else break; msg_counter++; -- cgit v1.2.3