Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932925AbbLBPmp (ORCPT ); Wed, 2 Dec 2015 10:42:45 -0500 Received: from mail-io0-f172.google.com ([209.85.223.172]:36641 "EHLO mail-io0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932893AbbLBPmd (ORCPT ); Wed, 2 Dec 2015 10:42:33 -0500 From: Seth Forshee To: "Eric W. Biederman" , Serge Hallyn , James Morris , "Serge E. Hallyn" Cc: Alexander Viro , Richard Weinberger , Austin S Hemmelgarn , Miklos Szeredi , linux-bcache@vger.kernel.org, dm-devel@redhat.com, linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mtd@lists.infradead.org, linux-fsdevel@vger.kernel.org, fuse-devel@lists.sourceforge.net, linux-security-module@vger.kernel.org, selinux@tycho.nsa.gov, Seth Forshee Subject: [PATCH 15/19] capabilities: Allow privileged user in s_user_ns to set file caps Date: Wed, 2 Dec 2015 09:40:15 -0600 Message-Id: <1449070821-73820-16-git-send-email-seth.forshee@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1449070821-73820-1-git-send-email-seth.forshee@canonical.com> References: <1449070821-73820-1-git-send-email-seth.forshee@canonical.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2054 Lines: 64 A privileged user in a super block's s_user_ns is privileged towards that file system and thus should be allowed to set file capabilities. The file capabilities will not be trusted outside of s_user_ns, so an unprivileged user cannot use this to gain privileges in a user namespace where they are not already privileged. Signed-off-by: Seth Forshee --- security/commoncap.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/security/commoncap.c b/security/commoncap.c index 2119421613f6..d6c80c19c449 100644 --- a/security/commoncap.c +++ b/security/commoncap.c @@ -653,15 +653,17 @@ int cap_bprm_secureexec(struct linux_binprm *bprm) int cap_inode_setxattr(struct dentry *dentry, const char *name, const void *value, size_t size, int flags) { + struct user_namespace *user_ns = dentry->d_sb->s_user_ns; + if (!strcmp(name, XATTR_NAME_CAPS)) { - if (!capable(CAP_SETFCAP)) + if (!ns_capable(user_ns, CAP_SETFCAP)) return -EPERM; return 0; } if (!strncmp(name, XATTR_SECURITY_PREFIX, sizeof(XATTR_SECURITY_PREFIX) - 1) && - !capable(CAP_SYS_ADMIN)) + !ns_capable(user_ns, CAP_SYS_ADMIN)) return -EPERM; return 0; } @@ -679,15 +681,17 @@ int cap_inode_setxattr(struct dentry *dentry, const char *name, */ int cap_inode_removexattr(struct dentry *dentry, const char *name) { + struct user_namespace *user_ns = dentry->d_sb->s_user_ns; + if (!strcmp(name, XATTR_NAME_CAPS)) { - if (!capable(CAP_SETFCAP)) + if (!ns_capable(user_ns, CAP_SETFCAP)) return -EPERM; return 0; } if (!strncmp(name, XATTR_SECURITY_PREFIX, sizeof(XATTR_SECURITY_PREFIX) - 1) && - !capable(CAP_SYS_ADMIN)) + !ns_capable(user_ns, CAP_SYS_ADMIN)) return -EPERM; return 0; } -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/