From: KP Singh <kpsingh@chromium.org>
To: linux-kernel@vger.kernel.org, bpf@vger.kernel.org,
linux-security-module@vger.kernel.org
Cc: Mikko Ylinen <mikko.ylinen@linux.intel.com>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
James Morris <jmorris@namei.org>,
Kees Cook <keescook@chromium.org>, Jann Horn <jannh@google.com>
Subject: [PATCH bpf] security: Fix the default value of fs_context_parse_param hook
Date: Thu, 30 Apr 2020 17:52:40 +0200 [thread overview]
Message-ID: <20200430155240.68748-1-kpsingh@chromium.org> (raw)
From: KP Singh <kpsingh@google.com>
security_fs_context_parse_param is called by vfs_parse_fs_param and
a succussful return value (i.e 0) implies that a parameter will be
consumed by the LSM framework. This stops all further parsing of the
parmeter by VFS. Furthermore, if an LSM hook returns a success, the
remaining LSM hooks are not invoked for the parameter.
The current default behavior of returning success means that all the
parameters are expected to be parsed by the LSM hook and none of them
end up being populated by vfs in fs_context
This was noticed when lsm=bpf is supplied on the command line before any
other LSM. As the bpf lsm uses this default value to implement a default
hook, this resulted in a failure to parse any fs_context parameters and
a failure to mount the root filesystem.
Fixes: 98e828a0650f ("security: Refactor declaration of LSM hooks")
Reported-by: Mikko Ylinen <mikko.ylinen@linux.intel.com>
Signed-off-by: KP Singh <kpsingh@google.com>
---
include/linux/lsm_hook_defs.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index 9cd4455528e5..1bdd027766d4 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -55,7 +55,7 @@ LSM_HOOK(void, LSM_RET_VOID, bprm_committing_creds, struct linux_binprm *bprm)
LSM_HOOK(void, LSM_RET_VOID, bprm_committed_creds, struct linux_binprm *bprm)
LSM_HOOK(int, 0, fs_context_dup, struct fs_context *fc,
struct fs_context *src_sc)
-LSM_HOOK(int, 0, fs_context_parse_param, struct fs_context *fc,
+LSM_HOOK(int, -ENOPARAM, fs_context_parse_param, struct fs_context *fc,
struct fs_parameter *param)
LSM_HOOK(int, 0, sb_alloc_security, struct super_block *sb)
LSM_HOOK(void, LSM_RET_VOID, sb_free_security, struct super_block *sb)
--
2.26.2.303.gf8c07b1a785-goog
next reply other threads:[~2020-04-30 15:52 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-30 15:52 KP Singh [this message]
2020-05-01 3:46 ` [PATCH bpf] security: Fix the default value of fs_context_parse_param hook James Morris
2020-05-07 5:50 ` Alexei Starovoitov
2020-05-01 7:30 ` Mikko Ylinen
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200430155240.68748-1-kpsingh@chromium.org \
--to=kpsingh@chromium.org \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=jannh@google.com \
--cc=jmorris@namei.org \
--cc=keescook@chromium.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-security-module@vger.kernel.org \
--cc=mikko.ylinen@linux.intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).