From 39fda8db80c9da028bc78ef444a51ea56f3cf0ad Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Tue, 3 Apr 2012 18:36:26 -0700 Subject: [PATCH] userns: Replace netlink uses of cap_raised with capable. In 2009 Philip Reiser notied that a few users of netlink connector interface needed a capability check and added the idiom cap_raised(nsp->eff_cap, CAP_SYS_ADMIN) to a few of them, on the premise that netlink was asynchronous. In 2011 Patrick McHardy noticed we were being silly because netlink is synchronous and removed eff_cap from the netlink_skb_params and changed the idiom to cap_raised(current_cap(), CAP_SYS_ADMIN). Looking at those spots with a fresh eye we should be calling capable(CAP_SYS_ADMIN). The only reason I can see for not calling capable is that it once appeared we were not in the same task as the caller which would have made calling capable() impossible. In the initial user_namespace the only difference between between cap_raised(current_cap(), CAP_SYS_ADMIN) and capable(CAP_SYS_ADMIN) are a few sanity checks and the fact that capable(CAP_SYS_ADMIN) sets PF_SUPERPRIV if we use the capability. Since we are going to be using root privilege setting PF_SUPERPRIV seems the right thing to do. The motivation for this that patch is that in a child user namespace cap_raised(current_cap(),...) tests your capabilities with respect to that child user namespace not capabilities in the initial user namespace and thus will allow processes that should be unprivielged to use the kernel services that are only protected with cap_raised(current_cap(),..). To fix possible user_namespace issues and to just clean up the code replace cap_raised(current_cap(), CAP_SYS_ADMIN) with capable(CAP_SYS_ADMIN). Acked-by: Serge E. Hallyn Reviewed-by: James Morris Acked-by: Andrew G. Morgan Cc: Patrick McHardy Cc: Philipp Reisner Cc: Serge E. Hallyn Cc: Vasiliy Kulikov Cc: David Howells Signed-off-by: Eric W. Biederman --- drivers/block/drbd/drbd_nl.c | 2 +- drivers/md/dm-log-userspace-transfer.c | 2 +- drivers/video/uvesafb.c | 2 +- 3 files changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c index abfaacaaf34..946166e1395 100644 --- a/drivers/block/drbd/drbd_nl.c +++ b/drivers/block/drbd/drbd_nl.c @@ -2297,7 +2297,7 @@ static void drbd_connector_callback(struct cn_msg *req, struct netlink_skb_parms return; } - if (!cap_raised(current_cap(), CAP_SYS_ADMIN)) { + if (!capable(CAP_SYS_ADMIN)) { retcode = ERR_PERM; goto fail; } diff --git a/drivers/md/dm-log-userspace-transfer.c b/drivers/md/dm-log-userspace-transfer.c index 1f23e048f07..08d9a207259 100644 --- a/drivers/md/dm-log-userspace-transfer.c +++ b/drivers/md/dm-log-userspace-transfer.c @@ -134,7 +134,7 @@ static void cn_ulog_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp) { struct dm_ulog_request *tfr = (struct dm_ulog_request *)(msg + 1); - if (!cap_raised(current_cap(), CAP_SYS_ADMIN)) + if (!capable(CAP_SYS_ADMIN)) return; spin_lock(&receiving_list_lock); diff --git a/drivers/video/uvesafb.c b/drivers/video/uvesafb.c index 260cca7ddb4..9f7d27a6bdb 100644 --- a/drivers/video/uvesafb.c +++ b/drivers/video/uvesafb.c @@ -73,7 +73,7 @@ static void uvesafb_cn_callback(struct cn_msg *msg, struct netlink_skb_parms *ns struct uvesafb_task *utask; struct uvesafb_ktask *task; - if (!cap_raised(current_cap(), CAP_SYS_ADMIN)) + if (!capable(CAP_SYS_ADMIN)) return; if (msg->seq >= UVESAFB_TASKS_MAX)