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authorLinus Torvalds <torvalds@linux-foundation.org>2017-02-22 11:44:32 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-02-22 11:44:32 -0800
commitb2064617c74f301dab1448f1f9c8dbb3c8021058 (patch)
tree02998695437a023316103256e6c0242e47e4b5eb /security
parente30aee9e10bb5168579e047f05c3d13d09e23356 (diff)
parent17627157cda13089d8a6c1c2d35acb07334b899c (diff)
Merge tag 'driver-core-4.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core
Pull driver core updates from Greg KH: "Here is the "small" driver core patches for 4.11-rc1. Not much here, some firmware documentation and self-test updates, a debugfs code formatting issue, and a new feature for call_usermodehelper to make it more robust on systems that want to lock it down in a more secure way. All of these have been linux-next for a while now with no reported issues" * tag 'driver-core-4.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: kernfs: handle null pointers while printing node name and path Introduce STATIC_USERMODEHELPER to mediate call_usermodehelper() Make static usermode helper binaries constant kmod: make usermodehelper path a const string firmware: revamp firmware documentation selftests: firmware: send expected errors to /dev/null selftests: firmware: only modprobe if driver is missing platform: Print the resource range if device failed to claim kref: prefer atomic_inc_not_zero to atomic_add_unless debugfs: improve formatting of debugfs_real_fops()
Diffstat (limited to 'security')
-rw-r--r--security/Kconfig35
-rw-r--r--security/keys/request_key.c7
2 files changed, 39 insertions, 3 deletions
diff --git a/security/Kconfig b/security/Kconfig
index 118f4549404e..d900f47eaa68 100644
--- a/security/Kconfig
+++ b/security/Kconfig
@@ -158,6 +158,41 @@ config HARDENED_USERCOPY_PAGESPAN
been removed. This config is intended to be used only while
trying to find such users.
+config STATIC_USERMODEHELPER
+ bool "Force all usermode helper calls through a single binary"
+ help
+ By default, the kernel can call many different userspace
+ binary programs through the "usermode helper" kernel
+ interface. Some of these binaries are statically defined
+ either in the kernel code itself, or as a kernel configuration
+ option. However, some of these are dynamically created at
+ runtime, or can be modified after the kernel has started up.
+ To provide an additional layer of security, route all of these
+ calls through a single executable that can not have its name
+ changed.
+
+ Note, it is up to this single binary to then call the relevant
+ "real" usermode helper binary, based on the first argument
+ passed to it. If desired, this program can filter and pick
+ and choose what real programs are called.
+
+ If you wish for all usermode helper programs are to be
+ disabled, choose this option and then set
+ STATIC_USERMODEHELPER_PATH to an empty string.
+
+config STATIC_USERMODEHELPER_PATH
+ string "Path to the static usermode helper binary"
+ depends on STATIC_USERMODEHELPER
+ default "/sbin/usermode-helper"
+ help
+ The binary called by the kernel when any usermode helper
+ program is wish to be run. The "real" application's name will
+ be in the first argument passed to this program on the command
+ line.
+
+ If you wish for all usermode helper programs to be disabled,
+ specify an empty string here (i.e. "").
+
source security/selinux/Kconfig
source security/smack/Kconfig
source security/tomoyo/Kconfig
diff --git a/security/keys/request_key.c b/security/keys/request_key.c
index 43affcf10b22..9822e500d50d 100644
--- a/security/keys/request_key.c
+++ b/security/keys/request_key.c
@@ -72,7 +72,7 @@ static void umh_keys_cleanup(struct subprocess_info *info)
/*
* Call a usermode helper with a specific session keyring.
*/
-static int call_usermodehelper_keys(char *path, char **argv, char **envp,
+static int call_usermodehelper_keys(const char *path, char **argv, char **envp,
struct key *session_keyring, int wait)
{
struct subprocess_info *info;
@@ -95,6 +95,7 @@ static int call_sbin_request_key(struct key_construction *cons,
const char *op,
void *aux)
{
+ static char const request_key[] = "/sbin/request-key";
const struct cred *cred = current_cred();
key_serial_t prkey, sskey;
struct key *key = cons->key, *authkey = cons->authkey, *keyring,
@@ -161,7 +162,7 @@ static int call_sbin_request_key(struct key_construction *cons,
/* set up the argument list */
i = 0;
- argv[i++] = "/sbin/request-key";
+ argv[i++] = (char *)request_key;
argv[i++] = (char *) op;
argv[i++] = key_str;
argv[i++] = uid_str;
@@ -172,7 +173,7 @@ static int call_sbin_request_key(struct key_construction *cons,
argv[i] = NULL;
/* do it */
- ret = call_usermodehelper_keys(argv[0], argv, envp, keyring,
+ ret = call_usermodehelper_keys(request_key, argv, envp, keyring,
UMH_WAIT_PROC);
kdebug("usermode -> 0x%x", ret);
if (ret >= 0) {