From patchwork Mon May 9 19:55:47 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kamal Mostafa X-Patchwork-Id: 620198 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id 3r3Y7q4fnYz9t80; Tue, 10 May 2016 05:57:27 +1000 (AEST) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1azrIx-0006ra-9k; Mon, 09 May 2016 19:57:23 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.76) (envelope-from ) id 1azrIj-0006j2-24 for kernel-team@lists.ubuntu.com; Mon, 09 May 2016 19:57:09 +0000 Received: from 1.general.kamal.us.vpn ([10.172.68.52] helo=fourier) by youngberry.canonical.com with esmtpsa (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.76) (envelope-from ) id 1azrIi-0006Zs-Jv; Mon, 09 May 2016 19:57:08 +0000 Received: from kamal by fourier with local (Exim 4.86_2) (envelope-from ) id 1azrIf-0002FN-SL; Mon, 09 May 2016 12:57:05 -0700 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Subject: [PATCH 4.2.y-ckt 29/59] IB/security: Restrict use of the write() interface Date: Mon, 9 May 2016 12:55:47 -0700 Message-Id: <1462823777-8384-30-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1462823777-8384-1-git-send-email-kamal@canonical.com> References: <1462823777-8384-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 4.2 Cc: Jason Gunthorpe , Doug Ledford , Linus Torvalds , Kamal Mostafa X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com 4.2.8-ckt10 -stable review patch. If anyone has any objections, please let me know. ---8<------------------------------------------------------------ From: Jason Gunthorpe commit e6bd18f57aad1a2d1ef40e646d03ed0f2515c9e3 upstream. The drivers/infiniband stack uses write() as a replacement for bi-directional ioctl(). This is not safe. There are ways to trigger write calls that result in the return structure that is normally written to user space being shunted off to user specified kernel memory instead. For the immediate repair, detect and deny suspicious accesses to the write API. For long term, update the user space libraries and the kernel API to something that doesn't present the same security vulnerabilities (likely a structured ioctl() interface). The impacted uAPI interfaces are generally only available if hardware from drivers/infiniband is installed in the system. Reported-by: Jann Horn Signed-off-by: Linus Torvalds Signed-off-by: Jason Gunthorpe [ Expanded check to all known write() entry points ] Signed-off-by: Doug Ledford [ kamal: backport to 4.2-stable: no staging/rdma/ ] Signed-off-by: Kamal Mostafa --- drivers/infiniband/core/ucm.c | 4 ++++ drivers/infiniband/core/ucma.c | 3 +++ drivers/infiniband/core/uverbs_main.c | 5 +++++ drivers/infiniband/hw/qib/qib_file_ops.c | 5 +++++ include/rdma/ib.h | 16 ++++++++++++++++ 5 files changed, 33 insertions(+) diff --git a/drivers/infiniband/core/ucm.c b/drivers/infiniband/core/ucm.c index 0094810..aca6043 100644 --- a/drivers/infiniband/core/ucm.c +++ b/drivers/infiniband/core/ucm.c @@ -48,6 +48,7 @@ #include +#include #include #include #include @@ -1104,6 +1105,9 @@ static ssize_t ib_ucm_write(struct file *filp, const char __user *buf, struct ib_ucm_cmd_hdr hdr; ssize_t result; + if (WARN_ON_ONCE(!ib_safe_file_access(filp))) + return -EACCES; + if (len < sizeof(hdr)) return -EINVAL; diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c index 29b2121..66f1ca8 100644 --- a/drivers/infiniband/core/ucma.c +++ b/drivers/infiniband/core/ucma.c @@ -1474,6 +1474,9 @@ static ssize_t ucma_write(struct file *filp, const char __user *buf, struct rdma_ucm_cmd_hdr hdr; ssize_t ret; + if (WARN_ON_ONCE(!ib_safe_file_access(filp))) + return -EACCES; + if (len < sizeof(hdr)) return -EINVAL; diff --git a/drivers/infiniband/core/uverbs_main.c b/drivers/infiniband/core/uverbs_main.c index 15f4126..77c04a3 100644 --- a/drivers/infiniband/core/uverbs_main.c +++ b/drivers/infiniband/core/uverbs_main.c @@ -48,6 +48,8 @@ #include +#include + #include "uverbs.h" MODULE_AUTHOR("Roland Dreier"); @@ -614,6 +616,9 @@ static ssize_t ib_uverbs_write(struct file *filp, const char __user *buf, struct ib_uverbs_cmd_hdr hdr; __u32 flags; + if (WARN_ON_ONCE(!ib_safe_file_access(filp))) + return -EACCES; + if (count < sizeof hdr) return -EINVAL; diff --git a/drivers/infiniband/hw/qib/qib_file_ops.c b/drivers/infiniband/hw/qib/qib_file_ops.c index 7258818..619154e 100644 --- a/drivers/infiniband/hw/qib/qib_file_ops.c +++ b/drivers/infiniband/hw/qib/qib_file_ops.c @@ -45,6 +45,8 @@ #include #include +#include + #include "qib.h" #include "qib_common.h" #include "qib_user_sdma.h" @@ -2067,6 +2069,9 @@ static ssize_t qib_write(struct file *fp, const char __user *data, ssize_t ret = 0; void *dest; + if (WARN_ON_ONCE(!ib_safe_file_access(fp))) + return -EACCES; + if (count < sizeof(cmd.type)) { ret = -EINVAL; goto bail; diff --git a/include/rdma/ib.h b/include/rdma/ib.h index cf8f9e7..a6b9370 100644 --- a/include/rdma/ib.h +++ b/include/rdma/ib.h @@ -34,6 +34,7 @@ #define _RDMA_IB_H #include +#include struct ib_addr { union { @@ -86,4 +87,19 @@ struct sockaddr_ib { __u64 sib_scope_id; }; +/* + * The IB interfaces that use write() as bi-directional ioctl() are + * fundamentally unsafe, since there are lots of ways to trigger "write()" + * calls from various contexts with elevated privileges. That includes the + * traditional suid executable error message writes, but also various kernel + * interfaces that can write to file descriptors. + * + * This function provides protection for the legacy API by restricting the + * calling context. + */ +static inline bool ib_safe_file_access(struct file *filp) +{ + return filp->f_cred == current_cred() && segment_eq(get_fs(), USER_DS); +} + #endif /* _RDMA_IB_H */