From: "Mickaël Salaün" <mic@digikod.net>
To: linux-kernel@vger.kernel.org
Cc: "Mickaël Salaün" <mic@digikod.net>,
"Aleksa Sarai" <cyphar@cyphar.com>,
"Alexei Starovoitov" <ast@kernel.org>,
"Al Viro" <viro@zeniv.linux.org.uk>,
"Andy Lutomirski" <luto@kernel.org>,
"Christian Heimes" <christian@python.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Deven Bowers" <deven.desai@linux.microsoft.com>,
"Eric Chiang" <ericchiang@google.com>,
"Florian Weimer" <fweimer@redhat.com>,
"James Morris" <jmorris@namei.org>, "Jan Kara" <jack@suse.cz>,
"Jann Horn" <jannh@google.com>,
"Jonathan Corbet" <corbet@lwn.net>,
"Kees Cook" <keescook@chromium.org>,
"Matthew Garrett" <mjg59@google.com>,
"Matthew Wilcox" <willy@infradead.org>,
"Michael Kerrisk" <mtk.manpages@gmail.com>,
"Mickaël Salaün" <mickael.salaun@ssi.gouv.fr>,
"Mimi Zohar" <zohar@linux.ibm.com>,
"Philippe Trébuchet" <philippe.trebuchet@ssi.gouv.fr>,
"Scott Shell" <scottsh@microsoft.com>,
"Sean Christopherson" <sean.j.christopherson@intel.com>,
"Shuah Khan" <shuah@kernel.org>,
"Steve Dower" <steve.dower@python.org>,
"Steve Grubb" <sgrubb@redhat.com>,
"Thibaut Sautereau" <thibaut.sautereau@ssi.gouv.fr>,
"Vincent Strubel" <vincent.strubel@ssi.gouv.fr>,
kernel-hardening@lists.openwall.com, linux-api@vger.kernel.org,
linux-security-module@vger.kernel.org,
linux-fsdevel@vger.kernel.org
Subject: [PATCH v3 2/5] fs: Add a MAY_EXECMOUNT flag to infer the noexec mount property
Date: Tue, 28 Apr 2020 19:51:26 +0200 [thread overview]
Message-ID: <20200428175129.634352-3-mic@digikod.net> (raw)
In-Reply-To: <20200428175129.634352-1-mic@digikod.net>
An LSM doesn't get path information related to an access request to open
an inode. This new (internal) MAY_EXECMOUNT flag enables an LSM to
check if the underlying mount point of an inode is marked as executable.
This is useful to implement a security policy taking advantage of the
noexec mount option.
This flag is set according to path_noexec(), which checks if a mount
point is mounted with MNT_NOEXEC or if the underlying superblock is
SB_I_NOEXEC.
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Reviewed-by: Philippe Trébuchet <philippe.trebuchet@ssi.gouv.fr>
Reviewed-by: Thibaut Sautereau <thibaut.sautereau@ssi.gouv.fr>
Cc: Aleksa Sarai <cyphar@cyphar.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Kees Cook <keescook@chromium.org>
---
fs/namei.c | 2 ++
include/linux/fs.h | 2 ++
2 files changed, 4 insertions(+)
diff --git a/fs/namei.c b/fs/namei.c
index a320371899cf..33b6d372e74a 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2849,6 +2849,8 @@ static int may_open(const struct path *path, int acc_mode, int flag)
break;
}
+ /* Pass the mount point executability. */
+ acc_mode |= path_noexec(path) ? 0 : MAY_EXECMOUNT;
error = inode_permission(inode, MAY_OPEN | acc_mode);
if (error)
return error;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index f5be4be7c01d..9213147d8636 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -103,6 +103,8 @@ typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
#define MAY_NOT_BLOCK 0x00000080
/* the inode is opened with RESOLVE_MAYEXEC */
#define MAY_OPENEXEC 0x00000100
+/* the mount point is marked as executable */
+#define MAY_EXECMOUNT 0x00000200
/*
* flags in file.f_mode. Note that FMODE_READ and FMODE_WRITE must correspond
--
2.26.2
next prev parent reply other threads:[~2020-04-28 17:51 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-28 17:51 [PATCH v3 0/5] Add support for RESOLVE_MAYEXEC Mickaël Salaün
2020-04-28 17:51 ` [PATCH v3 1/5] fs: Add support for a RESOLVE_MAYEXEC flag on openat2(2) Mickaël Salaün
2020-05-01 4:04 ` James Morris
2020-05-01 14:14 ` Mickaël Salaün
2020-04-28 17:51 ` Mickaël Salaün [this message]
2020-05-01 4:02 ` [PATCH v3 2/5] fs: Add a MAY_EXECMOUNT flag to infer the noexec mount property James Morris
2020-05-01 14:17 ` Mickaël Salaün
2020-04-28 17:51 ` [PATCH v3 3/5] fs: Enable to enforce noexec mounts or file exec through RESOLVE_MAYEXEC Mickaël Salaün
2020-05-01 4:22 ` James Morris
2020-05-01 14:32 ` Mickaël Salaün
2020-05-01 18:05 ` James Morris
2020-04-28 17:51 ` [PATCH v3 4/5] selftest/openat2: Add tests for RESOLVE_MAYEXEC enforcing Mickaël Salaün
2020-04-28 17:51 ` [PATCH v3 5/5] doc: Add documentation for the fs.open_mayexec_enforce sysctl Mickaël Salaün
2020-04-28 19:21 ` [PATCH v3 0/5] Add support for RESOLVE_MAYEXEC Jann Horn
2020-04-28 21:20 ` Florian Weimer
2020-04-28 22:01 ` Jann Horn
2020-04-29 8:50 ` Mickaël Salaün
2020-05-01 11:47 ` Christian Heimes
2020-05-05 14:57 ` Mickaël Salaün
2020-04-30 1:54 ` Aleksa Sarai
2020-04-30 8:07 ` Christian Brauner
2020-04-30 10:45 ` Mickaël Salaün
2020-05-01 3:53 ` James Morris
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