From: Alexey Gladkov <gladkov.alexey@gmail.com>
To: LKML <linux-kernel@vger.kernel.org>,
Kernel Hardening <kernel-hardening@lists.openwall.com>,
Linux API <linux-api@vger.kernel.org>,
Linux FS Devel <linux-fsdevel@vger.kernel.org>,
Linux Security Module <linux-security-module@vger.kernel.org>
Cc: Akinobu Mita <akinobu.mita@gmail.com>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Alexey Dobriyan <adobriyan@gmail.com>,
Alexey Gladkov <gladkov.alexey@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Andy Lutomirski <luto@kernel.org>,
Daniel Micay <danielmicay@gmail.com>,
Djalal Harouni <tixxdz@gmail.com>,
"Dmitry V . Levin" <ldv@altlinux.org>,
"Eric W . Biederman" <ebiederm@xmission.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Ingo Molnar <mingo@kernel.org>,
"J . Bruce Fields" <bfields@fieldses.org>,
Jeff Layton <jlayton@poochiereds.net>,
Jonathan Corbet <corbet@lwn.net>,
Kees Cook <keescook@chromium.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Oleg Nesterov <oleg@redhat.com>,
Solar Designer <solar@openwall.com>,
Stephen Rothwell <sfr@canb.auug.org.au>
Subject: [PATCH v7 08/11] proc: instantiate only pids that we can ptrace on 'hidepid=4' mount option
Date: Sat, 25 Jan 2020 14:05:38 +0100 [thread overview]
Message-ID: <20200125130541.450409-9-gladkov.alexey@gmail.com> (raw)
In-Reply-To: <20200125130541.450409-1-gladkov.alexey@gmail.com>
If "hidepid=4" mount option is set then do not instantiate pids that
we can not ptrace. "hidepid=4" means that procfs should only contain
pids that the caller can ptrace.
Cc: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Djalal Harouni <tixxdz@gmail.com>
Signed-off-by: Alexey Gladkov <gladkov.alexey@gmail.com>
---
fs/proc/base.c | 15 +++++++++++++++
fs/proc/root.c | 14 +++++++++++---
include/linux/proc_fs.h | 1 +
3 files changed, 27 insertions(+), 3 deletions(-)
diff --git a/fs/proc/base.c b/fs/proc/base.c
index f4f1bcb28603..b55d205a7f6e 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -699,6 +699,14 @@ static bool has_pid_permissions(struct proc_fs_info *fs_info,
struct task_struct *task,
int hide_pid_min)
{
+ /*
+ * If 'hidpid' mount option is set force a ptrace check,
+ * we indicate that we are using a filesystem syscall
+ * by passing PTRACE_MODE_READ_FSCREDS
+ */
+ if (proc_fs_hide_pid(fs_info) == HIDEPID_NOT_PTRACABLE)
+ return ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS);
+
if (proc_fs_hide_pid(fs_info) < hide_pid_min)
return true;
if (in_group_p(proc_fs_pid_gid(fs_info)))
@@ -3274,7 +3282,14 @@ struct dentry *proc_pid_lookup(struct dentry *dentry, unsigned int flags)
if (!task)
goto out;
+ /* Limit procfs to only ptracable tasks */
+ if (proc_fs_hide_pid(fs_info) == HIDEPID_NOT_PTRACABLE) {
+ if (!has_pid_permissions(fs_info, task, HIDEPID_NO_ACCESS))
+ goto out_put_task;
+ }
+
result = proc_pid_instantiate(dentry, task, NULL);
+out_put_task:
put_task_struct(task);
out:
return result;
diff --git a/fs/proc/root.c b/fs/proc/root.c
index 3bb8df360cf7..57276cb65528 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -52,6 +52,15 @@ static const struct fs_parameter_description proc_fs_parameters = {
.specs = proc_param_specs,
};
+static inline int
+valid_hidepid(unsigned int value)
+{
+ return (value == HIDEPID_OFF ||
+ value == HIDEPID_NO_ACCESS ||
+ value == HIDEPID_INVISIBLE ||
+ value == HIDEPID_NOT_PTRACABLE);
+}
+
static int proc_parse_param(struct fs_context *fc, struct fs_parameter *param)
{
struct proc_fs_context *ctx = fc->fs_private;
@@ -68,10 +77,9 @@ static int proc_parse_param(struct fs_context *fc, struct fs_parameter *param)
break;
case Opt_hidepid:
+ if (!valid_hidepid(result.uint_32))
+ return invalf(fc, "proc: unknown value of hidepid.\n");
ctx->hidepid = result.uint_32;
- if (ctx->hidepid < HIDEPID_OFF ||
- ctx->hidepid > HIDEPID_INVISIBLE)
- return invalf(fc, "proc: hidepid value must be between 0 and 2.\n");
break;
default:
diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h
index f307940f8311..6822548405a7 100644
--- a/include/linux/proc_fs.h
+++ b/include/linux/proc_fs.h
@@ -17,6 +17,7 @@ enum {
HIDEPID_OFF = 0,
HIDEPID_NO_ACCESS = 1,
HIDEPID_INVISIBLE = 2,
+ HIDEPID_NOT_PTRACABLE = 4, /* Limit pids to only ptracable pids */
};
struct proc_fs_info {
--
2.24.1
next prev parent reply other threads:[~2020-01-25 13:07 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-25 13:05 [PATCH v7 00/11] proc: modernize proc to support multiple private instances Alexey Gladkov
2020-01-25 13:05 ` [PATCH v7 01/11] proc: Rename struct proc_fs_info to proc_fs_opts Alexey Gladkov
2020-01-25 13:05 ` [PATCH v7 02/11] proc: add proc_fs_info struct to store proc information Alexey Gladkov
2020-01-28 13:43 ` Oleg Nesterov
2020-01-28 14:58 ` Oleg Nesterov
2020-01-25 13:05 ` [PATCH v7 03/11] proc: move /proc/{self|thread-self} dentries to proc_fs_info Alexey Gladkov
2020-01-25 13:05 ` [PATCH v7 04/11] proc: move hide_pid, pid_gid from pid_namespace " Alexey Gladkov
2020-01-25 13:05 ` [PATCH v7 05/11] proc: add helpers to set and get proc hidepid and gid mount options Alexey Gladkov
2020-01-25 13:05 ` [PATCH v7 06/11] proc: support mounting procfs instances inside same pid namespace Alexey Gladkov
2020-01-25 13:05 ` [PATCH v7 07/11] proc: flush task dcache entries from all procfs instances Alexey Gladkov
2020-01-25 18:45 ` Linus Torvalds
2020-01-27 23:23 ` Alexey Gladkov
2020-01-25 13:05 ` Alexey Gladkov [this message]
2020-01-25 13:05 ` [PATCH v7 09/11] proc: add option to mount only a pids subset Alexey Gladkov
2020-01-25 13:05 ` [PATCH v7 10/11] docs: proc: add documentation for "hidepid=4" and "subset=pidfs" options and new mount behavior Alexey Gladkov
2020-01-25 13:05 ` [PATCH v7 11/11] proc: Move hidepid values to uapi as they are user interface to mount Alexey Gladkov
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