From: KP Singh <kpsingh@chromium.org>
To: linux-kernel@vger.kernel.org, bpf@vger.kernel.org,
linux-security-module@vger.kernel.org
Cc: "Alexei Starovoitov" <ast@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"James Morris" <jmorris@namei.org>,
"Kees Cook" <keescook@chromium.org>,
"Thomas Garnier" <thgarnie@chromium.org>,
"Michael Halcrow" <mhalcrow@google.com>,
"Paul Turner" <pjt@google.com>,
"Brendan Gregg" <brendan.d.gregg@gmail.com>,
"Jann Horn" <jannh@google.com>,
"Matthew Garrett" <mjg59@google.com>,
"Christian Brauner" <christian@brauner.io>,
"Mickaël Salaün" <mic@digikod.net>,
"Florent Revest" <revest@chromium.org>,
"Martin KaFai Lau" <kafai@fb.com>,
"Song Liu" <songliubraving@fb.com>, "Yonghong Song" <yhs@fb.com>,
"Serge E. Hallyn" <serge@hallyn.com>,
"Mauro Carvalho Chehab" <mchehab+samsung@kernel.org>,
"David S. Miller" <davem@davemloft.net>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Nicolas Ferre" <nicolas.ferre@microchip.com>,
"Stanislav Fomichev" <sdf@google.com>,
"Quentin Monnet" <quentin.monnet@netronome.com>,
"Andrey Ignatov" <rdna@fb.com>, "Joe Stringer" <joe@wand.net.nz>
Subject: [RFC v1 10/14] krsi: Handle attachment of the same program
Date: Tue, 10 Sep 2019 13:55:23 +0200 [thread overview]
Message-ID: <20190910115527.5235-11-kpsingh@chromium.org> (raw)
In-Reply-To: <20190910115527.5235-1-kpsingh@chromium.org>
From: KP Singh <kpsingh@google.com>
Allow the userspace to attach a newer version of a program without
having duplicates of the same program.
If BPF_F_ALLOW_OVERRIDE is passed, the attachment logic compares the
name of the new program to the names of existing attached programs. The
names are only compared till a "__" (or '\0', if there is no "__"). If
a successful match is found, the existing program is replaced with the
newer attachment.
./krsi Attaches "env_dumper__v1" followed by "env_dumper__v2"
to the process_execution hook of the KRSI LSM.
./krsi
./krsi
Before:
cat /sys/kernel/security/krsi/process_execution
env_dumper__v1
env_dumper__v2
After:
cat /sys/kernel/security/krsi/process_execution
env_dumper__v2
Signed-off-by: KP Singh <kpsingh@google.com>
---
security/krsi/ops.c | 53 ++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 52 insertions(+), 1 deletion(-)
diff --git a/security/krsi/ops.c b/security/krsi/ops.c
index 57bd304a03f4..1f4df920139c 100644
--- a/security/krsi/ops.c
+++ b/security/krsi/ops.c
@@ -65,11 +65,52 @@ static struct krsi_hook *get_hook_from_fd(int fd)
return ERR_PTR(ret);
}
+/*
+ * match_prog_name matches the name of the program till "__"
+ * or the end of the string is encountered. This allows
+ * a different version of the same program to be loaded.
+ *
+ * For example:
+ *
+ * env_dumper__v1 is matched with env_dumper__v2
+ *
+ */
+static bool match_prog_name(char *a, char *b)
+{
+ int m, n;
+ char *end;
+
+ end = strstr(a, "__");
+ n = end ? end - a : strlen(a);
+
+ end = strstr(b, "__");
+ m = end ? end - b : strlen(b);
+
+ if (m != n)
+ return false;
+
+ return strncmp(a, b, n) == 0;
+}
+
+static struct bpf_prog *find_attached_prog(struct bpf_prog_array *array,
+ struct bpf_prog *prog)
+{
+ struct bpf_prog_array_item *item = array->items;
+
+ for (; item->prog; item++) {
+ if (match_prog_name(item->prog->aux->name, prog->aux->name))
+ return item->prog;
+ }
+
+ return NULL;
+}
+
int krsi_prog_attach(const union bpf_attr *attr, struct bpf_prog *prog)
{
struct bpf_prog_array *old_array;
struct bpf_prog_array *new_array;
struct krsi_hook *h;
+ struct bpf_prog *old_prog;
int ret = 0;
h = get_hook_from_fd(attr->target_fd);
@@ -79,8 +120,18 @@ int krsi_prog_attach(const union bpf_attr *attr, struct bpf_prog *prog)
mutex_lock(&h->mutex);
old_array = rcu_dereference_protected(h->progs,
lockdep_is_held(&h->mutex));
+ /*
+ * Check if a matching program with already exists and replace
+ * the existing program will be overridden if BPF_F_ALLOW_OVERRIDE
+ * is specified in the attach flags.
+ */
+ old_prog = find_attached_prog(old_array, prog);
+ if (old_prog && !(attr->attach_flags & BPF_F_ALLOW_OVERRIDE)) {
+ ret = -EEXIST;
+ goto unlock;
+ }
- ret = bpf_prog_array_copy(old_array, NULL, prog, &new_array);
+ ret = bpf_prog_array_copy(old_array, old_prog, prog, &new_array);
if (ret < 0) {
ret = -ENOMEM;
goto unlock;
--
2.20.1
next prev parent reply other threads:[~2019-09-10 11:56 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-10 11:55 [RFC v1 00/14] Kernel Runtime Security Instrumentation KP Singh
2019-09-10 11:55 ` [RFC v1 01/14] krsi: Add a skeleton and config options for the KRSI LSM KP Singh
2019-09-10 11:55 ` [RFC v1 02/14] krsi: Introduce types for KRSI eBPF KP Singh
2019-09-10 11:55 ` [RFC v1 03/14] bpf: krsi: sync BPF UAPI header with tools KP Singh
2019-09-10 11:55 ` [RFC v1 04/14] krsi: Add support in libbpf for BPF_PROG_TYPE_KRSI KP Singh
2019-09-14 16:09 ` Yonghong Song
2019-09-10 11:55 ` [RFC v1 05/14] krsi: Initialize KRSI hooks and create files in securityfs KP Singh
2019-09-14 16:26 ` Yonghong Song
2019-09-10 11:55 ` [RFC v1 06/14] krsi: Implement eBPF operations, attachment and execution KP Singh
2019-09-14 16:56 ` Yonghong Song
2019-09-15 0:37 ` Yonghong Song
2019-09-10 11:55 ` [RFC v1 07/14] krsi: Check for premissions on eBPF attachment KP Singh
2019-09-10 11:55 ` [RFC v1 08/14] krsi: Show attached program names in hook read handler KP Singh
2019-09-10 11:55 ` [RFC v1 09/14] krsi: Add a helper function for bpf_perf_event_output KP Singh
2019-09-14 18:23 ` Yonghong Song
2019-09-10 11:55 ` KP Singh [this message]
2019-09-10 11:55 ` [RFC v1 11/14] krsi: Pin argument pages in bprm_check_security hook KP Singh
2019-09-10 11:55 ` [RFC v1 12/14] krsi: Add an eBPF helper function to get the value of an env variable KP Singh
2019-09-15 0:16 ` Yonghong Song
2019-09-16 13:00 ` KP Singh
2019-09-17 16:58 ` Yonghong Song
2019-09-17 19:36 ` KP Singh
2019-09-10 11:55 ` [RFC v1 13/14] krsi: Provide an example to read and log environment variables KP Singh
2019-09-15 0:24 ` Yonghong Song
2019-09-10 11:55 ` [RFC v1 14/14] krsi: Pin arg pages only when needed KP Singh
2019-09-15 0:33 ` Yonghong Song
2019-09-15 1:40 ` KP Singh
2019-09-15 19:45 ` Yonghong Song
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