From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933189Ab2JWQVR (ORCPT ); Tue, 23 Oct 2012 12:21:17 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:47867 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754531Ab2JWQVP (ORCPT ); Tue, 23 Oct 2012 12:21:15 -0400 Date: Tue, 23 Oct 2012 11:19:58 -0500 From: Serge Hallyn To: Stanislav Kinsbursky Cc: akpm@linux-foundation.org, catalin.marinas@arm.com, will.deacon@arm.com, dhowells@redhat.com, manfred@colorfullife.com, hughd@google.com, jmorris@namei.org, mtk.manpages@gmail.com, kosaki.motohiro@jp.fujitsu.com, paulmck@linux.vnet.ibm.com, sds@tycho.nsa.gov, devel@openvz.org, a.p.zijlstra@chello.nl, cmetcalf@tilera.com, linux-driver@qlogic.com, ron.mercer@qlogic.com, viro@zeniv.linux.org.uk, eparis@parisplace.org, tglx@linutronix.de, jitendra.kalsaria@qlogic.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, ebiederm@xmission.com, casey@schaufler-ca.com Subject: Re: [PATCH v6 03/10] ipc: segment key change helper introduced Message-ID: <20121023161958.GB9755@sergelap> References: <20121015155800.28348.23561.stgit@localhost.localdomain> <20121015155951.28348.65427.stgit@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20121015155951.28348.65427.stgit@localhost.localdomain> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Quoting Stanislav Kinsbursky (skinsbursky@parallels.com): > This patch introduces existent segment key changing infrastructure. > New function ipc_update_key() can be used change segment key, cuid, cgid > values. It checks for that new key is not used (except IPC_PRIVATE) prior to > set it on existent. > To make this possible, added copying of this fields from user-space in > __get_compat_ipc_perm() and __get_compat_ipc64_perm() functions. Also segment > search by key and lock were splitted into different functions, because > ipc_update_key() doesn't need to lock the segment during check that new key is > not used. > > Signed-off-by: Stanislav Kinsbursky Acked-by: Serge E. Hallyn > --- > ipc/compat.c | 6 ++++++ > ipc/util.c | 51 ++++++++++++++++++++++++++++++++++++++++++++++++--- > ipc/util.h | 2 ++ > 3 files changed, 56 insertions(+), 3 deletions(-) > > diff --git a/ipc/compat.c b/ipc/compat.c > index ad9518e..af30d13 100644 > --- a/ipc/compat.c > +++ b/ipc/compat.c > @@ -144,6 +144,9 @@ static inline int __get_compat_ipc64_perm(struct ipc64_perm *p64, > err = __get_user(p64->uid, &up64->uid); > err |= __get_user(p64->gid, &up64->gid); > err |= __get_user(p64->mode, &up64->mode); > + err |= __get_user(p64->cuid, &up64->cuid); > + err |= __get_user(p64->cgid, &up64->cgid); > + err |= __get_user(p64->key, &up64->key); > return err; > } > > @@ -155,6 +158,9 @@ static inline int __get_compat_ipc_perm(struct ipc64_perm *p, > err = __get_user(p->uid, &up->uid); > err |= __get_user(p->gid, &up->gid); > err |= __get_user(p->mode, &up->mode); > + err |= __get_user(p->cuid, &up->cuid); > + err |= __get_user(p->cgid, &up->cgid); > + err |= __get_user(p->key, &up->key); > return err; > } > > diff --git a/ipc/util.c b/ipc/util.c > index 503946e..faae296 100644 > --- a/ipc/util.c > +++ b/ipc/util.c > @@ -173,7 +173,7 @@ void __init ipc_init_proc_interface(const char *path, const char *header, > * @key: The key to find > * > * Requires ipc_ids.rw_mutex locked. > - * Returns the LOCKED pointer to the ipc structure if found or NULL > + * Returns the UNLOCKED pointer to the ipc structure if found or NULL > * if not. > * If key is found ipc points to the owning ipc structure > */ > @@ -195,7 +195,6 @@ static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key) > continue; > } > > - ipc_lock_by_ptr(ipc); > return ipc; > } > > @@ -203,6 +202,27 @@ static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key) > } > > /** > + * ipc_findkey_locked - find and lock a key in an ipc identifier set > + * @ids: Identifier set > + * @key: The key to find > + * > + * Requires ipc_ids.rw_mutex locked. > + * Returns the LOCKED pointer to the ipc structure if found or NULL > + * if not. > + * If key is found ipc points to the owning ipc structure > + */ > + > +static struct kern_ipc_perm *ipc_findkey_locked(struct ipc_ids *ids, key_t key) > +{ > + struct kern_ipc_perm *ipc; > + > + ipc = ipc_findkey(ids, key); > + if (ipc) > + ipc_lock_by_ptr(ipc); > + return ipc; > +} > + > +/** > * ipc_get_maxid - get the last assigned id > * @ids: IPC identifier set > * > @@ -388,7 +408,7 @@ retry: > * a new entry + read locks are not "upgradable" > */ > down_write(&ids->rw_mutex); > - ipcp = ipc_findkey(ids, params->key); > + ipcp = ipc_findkey_locked(ids, params->key); > if (ipcp == NULL) { > /* key not used */ > if (!(flg & IPC_CREAT)) > @@ -755,6 +775,31 @@ int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids, > } > > /** > + * ipc_update_key - update the key of an IPC. > + * @in: the permission given as input. > + * @out: the permission of the ipc to set. > + * > + * Common routine called by sys_shmctl(), sys_semctl(). sys_msgctl(). > + */ > +int ipc_update_key(struct ipc_ids *ids, struct ipc64_perm *in, > + struct kern_ipc_perm *out) > +{ > + > + if (in->key && out->key != in->key) { > + /* > + * Check for existent segment with the same key. > + * Note: ipc_ids.rw_mutex is taken for write already. > + */ > + if (ipc_findkey(ids, in->key)) > + return -EEXIST; > + } > + out->cuid = in->cuid; > + out->cgid = in->cgid; > + out->key = in->key; > + return 0; > +} > + > +/** > * ipc_update_perm - update the permissions of an IPC. > * @in: the permission given as input. > * @out: the permission of the ipc to set. > diff --git a/ipc/util.h b/ipc/util.h > index 3a9e558..271bded 100644 > --- a/ipc/util.h > +++ b/ipc/util.h > @@ -126,6 +126,8 @@ struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int); > > void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out); > void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out); > +int ipc_update_key(struct ipc_ids *ids, struct ipc64_perm *in, > + struct kern_ipc_perm *out); > int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out); > struct kern_ipc_perm *ipcctl_pre_down(struct ipc_namespace *ns, > struct ipc_ids *ids, int id, int cmd, > > -- > To unsubscribe from this list: send the line "unsubscribe linux-security-module" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html