From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.hallyn.com (mail.hallyn.com [178.63.66.53]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4143418B09; Wed, 30 Oct 2024 03:18:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=178.63.66.53 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730258288; cv=none; b=F6iirsOwu/hFnefOh/FMdG/4zK7p7lrlZEE5ztnkk1CsyECcqbKemVsQWaDUhgdomPji53pCgHfVA5UWDcJIX5gd3bNh3xAju05bb5vChY+F86o1uhh4iKx+61ON8cSY92UwQ+8/vk0f4AsSwfSqSLe3pgLjHL/skA3ILA6ufQc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730258288; c=relaxed/simple; bh=6ETqSpjax7dr+09qpp+3hZMqOWah/t0UWz5kzsR7B4s=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=JEL/LK8vi3BYTDORTKzFE8Zjo0p+4beg/wbDZx2T7wgR7s1jyXqrwquDeIPkZKoPioPNP5HqIjxp93flh610p1bVvnePj2oc+l7WS8Uo9YN1mS/pXz1yC49kWgeU7nw2gUgrKv60OMVcvpWHxDTP2FDM6AysTwwA2hMdMt7vHI8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=hallyn.com; spf=pass smtp.mailfrom=mail.hallyn.com; arc=none smtp.client-ip=178.63.66.53 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=hallyn.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=mail.hallyn.com Received: by mail.hallyn.com (Postfix, from userid 1001) id 0F46515AA; Tue, 29 Oct 2024 22:18:01 -0500 (CDT) Date: Tue, 29 Oct 2024 22:18:01 -0500 From: "Serge E. Hallyn" To: Jordan Rome Cc: linux-security-module@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Andrii Nakryiko , Kernel Team , Serge Hallyn , Yonghong Song Subject: Re: [v4] security: add trace event for cap_capable Message-ID: <20241030031801.GA149820@mail.hallyn.com> References: <20241030013314.2188163-1-linux@jordanrome.com> Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241030013314.2188163-1-linux@jordanrome.com> On Tue, Oct 29, 2024 at 06:33:14PM -0700, Jordan Rome wrote: > In cases where we want a stable way to observe/trace > cap_capable (e.g. protection from inlining and API updates) > add a tracepoint that passes: > - The credentials used > - The user namespace of the resource being accessed > - The user namespace in which the credential provides the > capability to access the targeted resource > - The capability to check for > - Bitmask of options defined in include/linux/security.h > - The return value of the check > > Signed-off-by: Jordan Rome Thanks. I'll pull this into the capability tree tomorrow so it can be tested in linux-next (and Andrii's ack unless he objects). > --- > MAINTAINERS | 1 + > include/trace/events/capability.h | 60 +++++++++++++++++++++++++++++++ > security/commoncap.c | 30 +++++++++++----- > 3 files changed, 83 insertions(+), 8 deletions(-) > create mode 100644 include/trace/events/capability.h > > diff --git a/MAINTAINERS b/MAINTAINERS > index cc40a9d9b8cd..210e9076c858 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -4994,6 +4994,7 @@ M: Serge Hallyn > L: linux-security-module@vger.kernel.org > S: Supported > F: include/linux/capability.h > +F: include/trace/events/capability.h > F: include/uapi/linux/capability.h > F: kernel/capability.c > F: security/commoncap.c > diff --git a/include/trace/events/capability.h b/include/trace/events/capability.h > new file mode 100644 > index 000000000000..e706ce690c38 > --- /dev/null > +++ b/include/trace/events/capability.h > @@ -0,0 +1,60 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +#undef TRACE_SYSTEM > +#define TRACE_SYSTEM capability > + > +#if !defined(_TRACE_CAPABILITY_H) || defined(TRACE_HEADER_MULTI_READ) > +#define _TRACE_CAPABILITY_H > + > +#include > +#include > +#include > + > +/** > + * cap_capable - called after it's determined if a task has a particular > + * effective capability > + * > + * @cred: The credentials used > + * @targ_ns: The user namespace of the resource being accessed > + * @capable_ns: The user namespace in which the credential provides the > + * capability to access the targeted resource. > + * This will be NULL if ret is not 0. > + * @cap: The capability to check for > + * @opts: Bitmask of options defined in include/linux/security.h > + * @ret: The return value of the check: 0 if it does, -ve if it does not > + * > + * Allows to trace calls to cap_capable in commoncap.c > + */ > +TRACE_EVENT(cap_capable, > + > + TP_PROTO(const struct cred *cred, struct user_namespace *targ_ns, > + struct user_namespace *capable_ns, int cap, unsigned int opts, int ret), > + > + TP_ARGS(cred, targ_ns, capable_ns, cap, opts, ret), > + > + TP_STRUCT__entry( > + __field(const struct cred *, cred) > + __field(struct user_namespace *, targ_ns) > + __field(struct user_namespace *, capable_ns) > + __field(int, cap) > + __field(unsigned int, opts) > + __field(int, ret) > + ), > + > + TP_fast_assign( > + __entry->cred = cred; > + __entry->targ_ns = targ_ns; > + __entry->capable_ns = capable_ns; > + __entry->cap = cap; > + __entry->opts = opts; > + __entry->ret = ret; > + ), > + > + TP_printk("cred %p, targ_ns %p, capable_ns %p, cap %d, opts %u, ret %d", > + __entry->cred, __entry->targ_ns, __entry->capable_ns, __entry->cap, > + __entry->opts, __entry->ret) > +); > + > +#endif /* _TRACE_CAPABILITY_H */ > + > +/* This part must be outside protection */ > +#include > diff --git a/security/commoncap.c b/security/commoncap.c > index 162d96b3a676..7a74eb27eebf 100644 > --- a/security/commoncap.c > +++ b/security/commoncap.c > @@ -27,6 +27,9 @@ > #include > #include > > +#define CREATE_TRACE_POINTS > +#include > + > /* > * If a non-root user executes a setuid-root binary in > * !secure(SECURE_NOROOT) mode, then we raise capabilities. > @@ -52,7 +55,7 @@ static void warn_setuid_and_fcaps_mixed(const char *fname) > /** > * cap_capable - Determine whether a task has a particular effective capability > * @cred: The credentials to use > - * @targ_ns: The user namespace in which we need the capability > + * @targ_ns: The user namespace of the resource being accessed > * @cap: The capability to check for > * @opts: Bitmask of options defined in include/linux/security.h > * > @@ -67,7 +70,9 @@ static void warn_setuid_and_fcaps_mixed(const char *fname) > int cap_capable(const struct cred *cred, struct user_namespace *targ_ns, > int cap, unsigned int opts) > { > - struct user_namespace *ns = targ_ns; > + int ret = -EPERM; > + struct user_namespace *capable_ns = NULL, > + *ns = targ_ns; > > /* See if cred has the capability in the target user namespace > * by examining the target user namespace and all of the target > @@ -75,22 +80,30 @@ int cap_capable(const struct cred *cred, struct user_namespace *targ_ns, > */ > for (;;) { > /* Do we have the necessary capabilities? */ > - if (ns == cred->user_ns) > - return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM; > + if (ns == cred->user_ns) { > + if (cap_raised(cred->cap_effective, cap)) { > + capable_ns = ns; > + ret = 0; > + } > + break; > + } > > /* > * If we're already at a lower level than we're looking for, > * we're done searching. > */ > if (ns->level <= cred->user_ns->level) > - return -EPERM; > + break; > > /* > * The owner of the user namespace in the parent of the > * user namespace has all caps. > */ > - if ((ns->parent == cred->user_ns) && uid_eq(ns->owner, cred->euid)) > - return 0; > + if ((ns->parent == cred->user_ns) && uid_eq(ns->owner, cred->euid)) { > + capable_ns = ns->parent; > + ret = 0; > + break; > + } > > /* > * If you have a capability in a parent user ns, then you have > @@ -99,7 +112,8 @@ int cap_capable(const struct cred *cred, struct user_namespace *targ_ns, > ns = ns->parent; > } > > - /* We never get here */ > + trace_cap_capable(cred, targ_ns, capable_ns, cap, opts, ret); > + return ret; > } > > /** > -- > 2.43.5