* [PATCH v3 1/3] LSM: Add /sys/kernel/security/lsm
2016-06-10 21:21 [PATCH v3 0/3] LSM: module hierarchy in /proc/.../attr Casey Schaufler
@ 2016-06-10 21:25 ` Casey Schaufler
2016-06-14 18:41 ` Kees Cook
2016-06-14 22:25 ` David A. Wheeler
2016-06-10 21:25 ` [PATCH v3 2/3] LSM: module hierarchy in /proc/.../attr Casey Schaufler
2016-06-10 21:25 ` [PATCH v3 3/3] LSM: Add context interface for proc attr Casey Schaufler
2 siblings, 2 replies; 13+ messages in thread
From: Casey Schaufler @ 2016-06-10 21:25 UTC (permalink / raw)
To: LSM, James Morris
Cc: John Johansen, Stephen Smalley, Paul Moore, Tetsuo Handa,
Kees Cook, LKLM, James Morris
Subject: [PATCH v3 1/3] LSM: Add /sys/kernel/security/lsm
I got tired of having to find indirect ways to
determine what security modules are active on a system.
I have added /sys/kernel/security/lsm, which contains a
comma separated list of the active security modules. No
more groping around in /proc/filesystems, which won't
help if the module doesn't support its own filesystem.
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
---
include/linux/lsm_hooks.h | 12 ++++--------
security/apparmor/lsm.c | 3 ++-
security/commoncap.c | 3 ++-
security/inode.c | 26 ++++++++++++++++++++++++--
security/loadpin/loadpin.c | 2 +-
security/security.c | 39 +++++++++++++++++++++++++++++++++++++++
security/selinux/hooks.c | 2 +-
security/smack/smack_lsm.c | 2 +-
security/tomoyo/tomoyo.c | 2 +-
security/yama/yama_lsm.c | 2 +-
10 files changed, 76 insertions(+), 17 deletions(-)
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 7ae3976..0bfd441 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -1841,6 +1841,7 @@ struct security_hook_list {
struct list_head list;
struct list_head *head;
union security_list_options hook;
+ char *lsm;
};
/*
@@ -1853,15 +1854,10 @@ struct security_hook_list {
{ .head = &security_hook_heads.HEAD, .hook = { .HEAD = HOOK } }
extern struct security_hook_heads security_hook_heads;
+extern char *lsm_names;
-static inline void security_add_hooks(struct security_hook_list *hooks,
- int count)
-{
- int i;
-
- for (i = 0; i < count; i++)
- list_add_tail_rcu(&hooks[i].list, hooks[i].head);
-}
+extern void security_add_hooks(struct security_hook_list *hooks, int count,
+ char *lsm);
#ifdef CONFIG_SECURITY_SELINUX_DISABLE
/*
diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
index 2660fbc..fb0fb03 100644
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c
@@ -880,7 +880,8 @@ static int __init apparmor_init(void)
aa_free_root_ns();
goto alloc_out;
}
- security_add_hooks(apparmor_hooks, ARRAY_SIZE(apparmor_hooks));
+ security_add_hooks(apparmor_hooks, ARRAY_SIZE(apparmor_hooks),
+ "apparmor");
/* Report that AppArmor successfully initialized */
apparmor_initialized = 1;
diff --git a/security/commoncap.c b/security/commoncap.c
index e7fadde..d101734 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -1090,7 +1090,8 @@ struct security_hook_list capability_hooks[] = {
void __init capability_add_hooks(void)
{
- security_add_hooks(capability_hooks, ARRAY_SIZE(capability_hooks));
+ security_add_hooks(capability_hooks, ARRAY_SIZE(capability_hooks),
+ "capability");
}
#endif /* CONFIG_SECURITY */
diff --git a/security/inode.c b/security/inode.c
index 28414b0..235ad82 100644
--- a/security/inode.c
+++ b/security/inode.c
@@ -20,6 +20,7 @@
#include <linux/init.h>
#include <linux/namei.h>
#include <linux/security.h>
+#include <linux/lsm_hooks.h>
#include <linux/magic.h>
static struct vfsmount *mount;
@@ -208,6 +209,21 @@ void securityfs_remove(struct dentry *dentry)
}
EXPORT_SYMBOL_GPL(securityfs_remove);
+#ifdef CONFIG_SECURITY
+static struct dentry *lsm_dentry;
+static ssize_t lsm_read(struct file *filp, char __user *buf, size_t count,
+ loff_t *ppos)
+{
+ return simple_read_from_buffer(buf, count, ppos, lsm_names,
+ strlen(lsm_names));
+}
+
+static const struct file_operations lsm_ops = {
+ .read = lsm_read,
+ .llseek = generic_file_llseek,
+};
+#endif
+
static int __init securityfs_init(void)
{
int retval;
@@ -217,9 +233,15 @@ static int __init securityfs_init(void)
return retval;
retval = register_filesystem(&fs_type);
- if (retval)
+ if (retval) {
sysfs_remove_mount_point(kernel_kobj, "security");
- return retval;
+ return retval;
+ }
+#ifdef CONFIG_SECURITY
+ lsm_dentry = securityfs_create_file("lsm", S_IRUGO, NULL, NULL,
+ &lsm_ops);
+#endif
+ return 0;
}
core_initcall(securityfs_init);
diff --git a/security/loadpin/loadpin.c b/security/loadpin/loadpin.c
index 89a46f1..1d82eae 100644
--- a/security/loadpin/loadpin.c
+++ b/security/loadpin/loadpin.c
@@ -182,7 +182,7 @@ static struct security_hook_list loadpin_hooks[] = {
void __init loadpin_add_hooks(void)
{
pr_info("ready to pin (currently %sabled)", enabled ? "en" : "dis");
- security_add_hooks(loadpin_hooks, ARRAY_SIZE(loadpin_hooks));
+ security_add_hooks(loadpin_hooks, ARRAY_SIZE(loadpin_hooks), "loadpin");
}
/* Should not be mutable after boot, so not listed in sysfs (perm == 0). */
diff --git a/security/security.c b/security/security.c
index c4bb47d..dd792d5 100644
--- a/security/security.c
+++ b/security/security.c
@@ -32,6 +32,7 @@
/* Maximum number of letters for an LSM name string */
#define SECURITY_NAME_MAX 10
+char *lsm_names;
/* Boot-time LSM user choice */
static __initdata char chosen_lsm[SECURITY_NAME_MAX + 1] =
CONFIG_DEFAULT_SECURITY;
@@ -78,6 +79,23 @@ static int __init choose_lsm(char *str)
}
__setup("security=", choose_lsm);
+static int lsm_append(char *new, char **result)
+{
+ char *cp;
+
+ if (*result == NULL) {
+ *result = kstrdup(new, GFP_KERNEL);
+ } else {
+ cp = kzalloc(strlen(*result) + strlen(new) + 2, GFP_KERNEL);
+ if (cp == NULL)
+ return -ENOMEM;
+ sprintf(cp, "%s,%s", *result, new);
+ kfree(*result);
+ *result = cp;
+ }
+ return 0;
+}
+
/**
* security_module_enable - Load given security module on boot ?
* @module: the name of the module
@@ -97,6 +115,27 @@ int __init security_module_enable(const char *module)
return !strcmp(module, chosen_lsm);
}
+/**
+ * security_add_hooks - Add a modules hooks to the hook lists.
+ * @hooks: the hooks to add
+ * @count: the number of hooks to add
+ * @lsm: the name of the security module
+ *
+ * Each LSM has to register its hooks with the infrastructure.
+ */
+void __init security_add_hooks(struct security_hook_list *hooks, int count,
+ char *lsm)
+{
+ int i;
+
+ for (i = 0; i < count; i++) {
+ hooks[i].lsm = lsm;
+ list_add_tail_rcu(&hooks[i].list, hooks[i].head);
+ }
+ if (lsm_append(lsm, &lsm_names) < 0)
+ panic("%s - Cannot get early memory.\n", __func__);
+}
+
/*
* Hook list operation macros.
*
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index a86d537..ed3a757 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -6233,7 +6233,7 @@ static __init int selinux_init(void)
0, SLAB_PANIC, NULL);
avc_init();
- security_add_hooks(selinux_hooks, ARRAY_SIZE(selinux_hooks));
+ security_add_hooks(selinux_hooks, ARRAY_SIZE(selinux_hooks), "selinux");
if (avc_add_callback(selinux_netcache_avc_callback, AVC_CALLBACK_RESET))
panic("SELinux: Unable to register AVC netcache callback\n");
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 6777295..3577009 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -4801,7 +4801,7 @@ static __init int smack_init(void)
/*
* Register with LSM
*/
- security_add_hooks(smack_hooks, ARRAY_SIZE(smack_hooks));
+ security_add_hooks(smack_hooks, ARRAY_SIZE(smack_hooks), "smack");
return 0;
}
diff --git a/security/tomoyo/tomoyo.c b/security/tomoyo/tomoyo.c
index 75c9987..edc52d6 100644
--- a/security/tomoyo/tomoyo.c
+++ b/security/tomoyo/tomoyo.c
@@ -542,7 +542,7 @@ static int __init tomoyo_init(void)
if (!security_module_enable("tomoyo"))
return 0;
/* register ourselves with the security framework */
- security_add_hooks(tomoyo_hooks, ARRAY_SIZE(tomoyo_hooks));
+ security_add_hooks(tomoyo_hooks, ARRAY_SIZE(tomoyo_hooks), "tomoyo");
printk(KERN_INFO "TOMOYO Linux initialized\n");
cred->security = &tomoyo_kernel_domain;
tomoyo_mm_init();
diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c
index 0309f21..f8ee60e 100644
--- a/security/yama/yama_lsm.c
+++ b/security/yama/yama_lsm.c
@@ -471,6 +471,6 @@ static inline void yama_init_sysctl(void) { }
void __init yama_add_hooks(void)
{
pr_info("Yama: becoming mindful.\n");
- security_add_hooks(yama_hooks, ARRAY_SIZE(yama_hooks));
+ security_add_hooks(yama_hooks, ARRAY_SIZE(yama_hooks), "yama");
yama_init_sysctl();
}
^ permalink raw reply related [flat|nested] 13+ messages in thread* Re: [PATCH v3 1/3] LSM: Add /sys/kernel/security/lsm
2016-06-10 21:25 ` [PATCH v3 1/3] LSM: Add /sys/kernel/security/lsm Casey Schaufler
@ 2016-06-14 18:41 ` Kees Cook
2016-06-14 19:32 ` Casey Schaufler
2016-06-14 22:25 ` David A. Wheeler
1 sibling, 1 reply; 13+ messages in thread
From: Kees Cook @ 2016-06-14 18:41 UTC (permalink / raw)
To: Casey Schaufler
Cc: LSM, James Morris, John Johansen, Stephen Smalley, Paul Moore,
Tetsuo Handa, LKLM, James Morris
On Fri, Jun 10, 2016 at 2:25 PM, Casey Schaufler <casey@schaufler-ca.com> wrote:
> Subject: [PATCH v3 1/3] LSM: Add /sys/kernel/security/lsm
>
> I got tired of having to find indirect ways to
> determine what security modules are active on a system.
> I have added /sys/kernel/security/lsm, which contains a
> comma separated list of the active security modules. No
> more groping around in /proc/filesystems, which won't
> help if the module doesn't support its own filesystem.
>
> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Looks good to me. I might tweak the copy code below, but otherwise:
Acked-by: Kees Cook <keescook@chromium.org>
>
> ---
> include/linux/lsm_hooks.h | 12 ++++--------
> security/apparmor/lsm.c | 3 ++-
> security/commoncap.c | 3 ++-
> security/inode.c | 26 ++++++++++++++++++++++++--
> security/loadpin/loadpin.c | 2 +-
> security/security.c | 39 +++++++++++++++++++++++++++++++++++++++
> security/selinux/hooks.c | 2 +-
> security/smack/smack_lsm.c | 2 +-
> security/tomoyo/tomoyo.c | 2 +-
> security/yama/yama_lsm.c | 2 +-
> 10 files changed, 76 insertions(+), 17 deletions(-)
>
> diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
> index 7ae3976..0bfd441 100644
> --- a/include/linux/lsm_hooks.h
> +++ b/include/linux/lsm_hooks.h
> @@ -1841,6 +1841,7 @@ struct security_hook_list {
> struct list_head list;
> struct list_head *head;
> union security_list_options hook;
> + char *lsm;
> };
>
> /*
> @@ -1853,15 +1854,10 @@ struct security_hook_list {
> { .head = &security_hook_heads.HEAD, .hook = { .HEAD = HOOK } }
>
> extern struct security_hook_heads security_hook_heads;
> +extern char *lsm_names;
>
> -static inline void security_add_hooks(struct security_hook_list *hooks,
> - int count)
> -{
> - int i;
> -
> - for (i = 0; i < count; i++)
> - list_add_tail_rcu(&hooks[i].list, hooks[i].head);
> -}
> +extern void security_add_hooks(struct security_hook_list *hooks, int count,
> + char *lsm);
>
> #ifdef CONFIG_SECURITY_SELINUX_DISABLE
> /*
> diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
> index 2660fbc..fb0fb03 100644
> --- a/security/apparmor/lsm.c
> +++ b/security/apparmor/lsm.c
> @@ -880,7 +880,8 @@ static int __init apparmor_init(void)
> aa_free_root_ns();
> goto alloc_out;
> }
> - security_add_hooks(apparmor_hooks, ARRAY_SIZE(apparmor_hooks));
> + security_add_hooks(apparmor_hooks, ARRAY_SIZE(apparmor_hooks),
> + "apparmor");
>
> /* Report that AppArmor successfully initialized */
> apparmor_initialized = 1;
> diff --git a/security/commoncap.c b/security/commoncap.c
> index e7fadde..d101734 100644
> --- a/security/commoncap.c
> +++ b/security/commoncap.c
> @@ -1090,7 +1090,8 @@ struct security_hook_list capability_hooks[] = {
>
> void __init capability_add_hooks(void)
> {
> - security_add_hooks(capability_hooks, ARRAY_SIZE(capability_hooks));
> + security_add_hooks(capability_hooks, ARRAY_SIZE(capability_hooks),
> + "capability");
> }
>
> #endif /* CONFIG_SECURITY */
> diff --git a/security/inode.c b/security/inode.c
> index 28414b0..235ad82 100644
> --- a/security/inode.c
> +++ b/security/inode.c
> @@ -20,6 +20,7 @@
> #include <linux/init.h>
> #include <linux/namei.h>
> #include <linux/security.h>
> +#include <linux/lsm_hooks.h>
> #include <linux/magic.h>
>
> static struct vfsmount *mount;
> @@ -208,6 +209,21 @@ void securityfs_remove(struct dentry *dentry)
> }
> EXPORT_SYMBOL_GPL(securityfs_remove);
>
> +#ifdef CONFIG_SECURITY
> +static struct dentry *lsm_dentry;
> +static ssize_t lsm_read(struct file *filp, char __user *buf, size_t count,
> + loff_t *ppos)
> +{
> + return simple_read_from_buffer(buf, count, ppos, lsm_names,
> + strlen(lsm_names));
> +}
> +
> +static const struct file_operations lsm_ops = {
> + .read = lsm_read,
> + .llseek = generic_file_llseek,
> +};
> +#endif
> +
> static int __init securityfs_init(void)
> {
> int retval;
> @@ -217,9 +233,15 @@ static int __init securityfs_init(void)
> return retval;
>
> retval = register_filesystem(&fs_type);
> - if (retval)
> + if (retval) {
> sysfs_remove_mount_point(kernel_kobj, "security");
> - return retval;
> + return retval;
> + }
> +#ifdef CONFIG_SECURITY
> + lsm_dentry = securityfs_create_file("lsm", S_IRUGO, NULL, NULL,
> + &lsm_ops);
> +#endif
> + return 0;
> }
>
> core_initcall(securityfs_init);
> diff --git a/security/loadpin/loadpin.c b/security/loadpin/loadpin.c
> index 89a46f1..1d82eae 100644
> --- a/security/loadpin/loadpin.c
> +++ b/security/loadpin/loadpin.c
> @@ -182,7 +182,7 @@ static struct security_hook_list loadpin_hooks[] = {
> void __init loadpin_add_hooks(void)
> {
> pr_info("ready to pin (currently %sabled)", enabled ? "en" : "dis");
> - security_add_hooks(loadpin_hooks, ARRAY_SIZE(loadpin_hooks));
> + security_add_hooks(loadpin_hooks, ARRAY_SIZE(loadpin_hooks), "loadpin");
> }
>
> /* Should not be mutable after boot, so not listed in sysfs (perm == 0). */
> diff --git a/security/security.c b/security/security.c
> index c4bb47d..dd792d5 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -32,6 +32,7 @@
> /* Maximum number of letters for an LSM name string */
> #define SECURITY_NAME_MAX 10
>
> +char *lsm_names;
> /* Boot-time LSM user choice */
> static __initdata char chosen_lsm[SECURITY_NAME_MAX + 1] =
> CONFIG_DEFAULT_SECURITY;
> @@ -78,6 +79,23 @@ static int __init choose_lsm(char *str)
> }
> __setup("security=", choose_lsm);
>
> +static int lsm_append(char *new, char **result)
> +{
> + char *cp;
> +
> + if (*result == NULL) {
> + *result = kstrdup(new, GFP_KERNEL);
> + } else {
> + cp = kzalloc(strlen(*result) + strlen(new) + 2, GFP_KERNEL);
> + if (cp == NULL)
> + return -ENOMEM;
> + sprintf(cp, "%s,%s", *result, new);
Instead of the kzalloc+sprintf, this could be:
cp = kasprintf(GFP_KERNEL, "%s,%s", *result, new);
if (!cp)
return -ENOMEM;
> + kfree(*result);
> + *result = cp;
> + }
> + return 0;
> +}
> +
> /**
> * security_module_enable - Load given security module on boot ?
> * @module: the name of the module
> @@ -97,6 +115,27 @@ int __init security_module_enable(const char *module)
> return !strcmp(module, chosen_lsm);
> }
>
> +/**
> + * security_add_hooks - Add a modules hooks to the hook lists.
> + * @hooks: the hooks to add
> + * @count: the number of hooks to add
> + * @lsm: the name of the security module
> + *
> + * Each LSM has to register its hooks with the infrastructure.
> + */
> +void __init security_add_hooks(struct security_hook_list *hooks, int count,
> + char *lsm)
> +{
> + int i;
> +
> + for (i = 0; i < count; i++) {
> + hooks[i].lsm = lsm;
> + list_add_tail_rcu(&hooks[i].list, hooks[i].head);
> + }
> + if (lsm_append(lsm, &lsm_names) < 0)
> + panic("%s - Cannot get early memory.\n", __func__);
> +}
> +
> /*
> * Hook list operation macros.
> *
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index a86d537..ed3a757 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -6233,7 +6233,7 @@ static __init int selinux_init(void)
> 0, SLAB_PANIC, NULL);
> avc_init();
>
> - security_add_hooks(selinux_hooks, ARRAY_SIZE(selinux_hooks));
> + security_add_hooks(selinux_hooks, ARRAY_SIZE(selinux_hooks), "selinux");
>
> if (avc_add_callback(selinux_netcache_avc_callback, AVC_CALLBACK_RESET))
> panic("SELinux: Unable to register AVC netcache callback\n");
> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> index 6777295..3577009 100644
> --- a/security/smack/smack_lsm.c
> +++ b/security/smack/smack_lsm.c
> @@ -4801,7 +4801,7 @@ static __init int smack_init(void)
> /*
> * Register with LSM
> */
> - security_add_hooks(smack_hooks, ARRAY_SIZE(smack_hooks));
> + security_add_hooks(smack_hooks, ARRAY_SIZE(smack_hooks), "smack");
>
> return 0;
> }
> diff --git a/security/tomoyo/tomoyo.c b/security/tomoyo/tomoyo.c
> index 75c9987..edc52d6 100644
> --- a/security/tomoyo/tomoyo.c
> +++ b/security/tomoyo/tomoyo.c
> @@ -542,7 +542,7 @@ static int __init tomoyo_init(void)
> if (!security_module_enable("tomoyo"))
> return 0;
> /* register ourselves with the security framework */
> - security_add_hooks(tomoyo_hooks, ARRAY_SIZE(tomoyo_hooks));
> + security_add_hooks(tomoyo_hooks, ARRAY_SIZE(tomoyo_hooks), "tomoyo");
> printk(KERN_INFO "TOMOYO Linux initialized\n");
> cred->security = &tomoyo_kernel_domain;
> tomoyo_mm_init();
> diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c
> index 0309f21..f8ee60e 100644
> --- a/security/yama/yama_lsm.c
> +++ b/security/yama/yama_lsm.c
> @@ -471,6 +471,6 @@ static inline void yama_init_sysctl(void) { }
> void __init yama_add_hooks(void)
> {
> pr_info("Yama: becoming mindful.\n");
> - security_add_hooks(yama_hooks, ARRAY_SIZE(yama_hooks));
> + security_add_hooks(yama_hooks, ARRAY_SIZE(yama_hooks), "yama");
> yama_init_sysctl();
> }
>
-Kees
--
Kees Cook
Chrome OS & Brillo Security
^ permalink raw reply [flat|nested] 13+ messages in thread* Re: [PATCH v3 1/3] LSM: Add /sys/kernel/security/lsm
2016-06-14 18:41 ` Kees Cook
@ 2016-06-14 19:32 ` Casey Schaufler
0 siblings, 0 replies; 13+ messages in thread
From: Casey Schaufler @ 2016-06-14 19:32 UTC (permalink / raw)
To: Kees Cook
Cc: LSM, James Morris, John Johansen, Stephen Smalley, Paul Moore,
Tetsuo Handa, LKLM, James Morris
On 6/14/2016 11:41 AM, Kees Cook wrote:
> On Fri, Jun 10, 2016 at 2:25 PM, Casey Schaufler <casey@schaufler-ca.com> wrote:
>> Subject: [PATCH v3 1/3] LSM: Add /sys/kernel/security/lsm
>>
>> I got tired of having to find indirect ways to
>> determine what security modules are active on a system.
>> I have added /sys/kernel/security/lsm, which contains a
>> comma separated list of the active security modules. No
>> more groping around in /proc/filesystems, which won't
>> help if the module doesn't support its own filesystem.
>>
>> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
> Looks good to me. I might tweak the copy code below, but otherwise:
>
> Acked-by: Kees Cook <keescook@chromium.org>
>
>> ---
>> include/linux/lsm_hooks.h | 12 ++++--------
>> security/apparmor/lsm.c | 3 ++-
>> security/commoncap.c | 3 ++-
>> security/inode.c | 26 ++++++++++++++++++++++++--
>> security/loadpin/loadpin.c | 2 +-
>> security/security.c | 39 +++++++++++++++++++++++++++++++++++++++
>> security/selinux/hooks.c | 2 +-
>> security/smack/smack_lsm.c | 2 +-
>> security/tomoyo/tomoyo.c | 2 +-
>> security/yama/yama_lsm.c | 2 +-
>> 10 files changed, 76 insertions(+), 17 deletions(-)
>>
>> diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
>> index 7ae3976..0bfd441 100644
>> --- a/include/linux/lsm_hooks.h
>> +++ b/include/linux/lsm_hooks.h
>> @@ -1841,6 +1841,7 @@ struct security_hook_list {
>> struct list_head list;
>> struct list_head *head;
>> union security_list_options hook;
>> + char *lsm;
>> };
>>
>> /*
>> @@ -1853,15 +1854,10 @@ struct security_hook_list {
>> { .head = &security_hook_heads.HEAD, .hook = { .HEAD = HOOK } }
>>
>> extern struct security_hook_heads security_hook_heads;
>> +extern char *lsm_names;
>>
>> -static inline void security_add_hooks(struct security_hook_list *hooks,
>> - int count)
>> -{
>> - int i;
>> -
>> - for (i = 0; i < count; i++)
>> - list_add_tail_rcu(&hooks[i].list, hooks[i].head);
>> -}
>> +extern void security_add_hooks(struct security_hook_list *hooks, int count,
>> + char *lsm);
>>
>> #ifdef CONFIG_SECURITY_SELINUX_DISABLE
>> /*
>> diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
>> index 2660fbc..fb0fb03 100644
>> --- a/security/apparmor/lsm.c
>> +++ b/security/apparmor/lsm.c
>> @@ -880,7 +880,8 @@ static int __init apparmor_init(void)
>> aa_free_root_ns();
>> goto alloc_out;
>> }
>> - security_add_hooks(apparmor_hooks, ARRAY_SIZE(apparmor_hooks));
>> + security_add_hooks(apparmor_hooks, ARRAY_SIZE(apparmor_hooks),
>> + "apparmor");
>>
>> /* Report that AppArmor successfully initialized */
>> apparmor_initialized = 1;
>> diff --git a/security/commoncap.c b/security/commoncap.c
>> index e7fadde..d101734 100644
>> --- a/security/commoncap.c
>> +++ b/security/commoncap.c
>> @@ -1090,7 +1090,8 @@ struct security_hook_list capability_hooks[] = {
>>
>> void __init capability_add_hooks(void)
>> {
>> - security_add_hooks(capability_hooks, ARRAY_SIZE(capability_hooks));
>> + security_add_hooks(capability_hooks, ARRAY_SIZE(capability_hooks),
>> + "capability");
>> }
>>
>> #endif /* CONFIG_SECURITY */
>> diff --git a/security/inode.c b/security/inode.c
>> index 28414b0..235ad82 100644
>> --- a/security/inode.c
>> +++ b/security/inode.c
>> @@ -20,6 +20,7 @@
>> #include <linux/init.h>
>> #include <linux/namei.h>
>> #include <linux/security.h>
>> +#include <linux/lsm_hooks.h>
>> #include <linux/magic.h>
>>
>> static struct vfsmount *mount;
>> @@ -208,6 +209,21 @@ void securityfs_remove(struct dentry *dentry)
>> }
>> EXPORT_SYMBOL_GPL(securityfs_remove);
>>
>> +#ifdef CONFIG_SECURITY
>> +static struct dentry *lsm_dentry;
>> +static ssize_t lsm_read(struct file *filp, char __user *buf, size_t count,
>> + loff_t *ppos)
>> +{
>> + return simple_read_from_buffer(buf, count, ppos, lsm_names,
>> + strlen(lsm_names));
>> +}
>> +
>> +static const struct file_operations lsm_ops = {
>> + .read = lsm_read,
>> + .llseek = generic_file_llseek,
>> +};
>> +#endif
>> +
>> static int __init securityfs_init(void)
>> {
>> int retval;
>> @@ -217,9 +233,15 @@ static int __init securityfs_init(void)
>> return retval;
>>
>> retval = register_filesystem(&fs_type);
>> - if (retval)
>> + if (retval) {
>> sysfs_remove_mount_point(kernel_kobj, "security");
>> - return retval;
>> + return retval;
>> + }
>> +#ifdef CONFIG_SECURITY
>> + lsm_dentry = securityfs_create_file("lsm", S_IRUGO, NULL, NULL,
>> + &lsm_ops);
>> +#endif
>> + return 0;
>> }
>>
>> core_initcall(securityfs_init);
>> diff --git a/security/loadpin/loadpin.c b/security/loadpin/loadpin.c
>> index 89a46f1..1d82eae 100644
>> --- a/security/loadpin/loadpin.c
>> +++ b/security/loadpin/loadpin.c
>> @@ -182,7 +182,7 @@ static struct security_hook_list loadpin_hooks[] = {
>> void __init loadpin_add_hooks(void)
>> {
>> pr_info("ready to pin (currently %sabled)", enabled ? "en" : "dis");
>> - security_add_hooks(loadpin_hooks, ARRAY_SIZE(loadpin_hooks));
>> + security_add_hooks(loadpin_hooks, ARRAY_SIZE(loadpin_hooks), "loadpin");
>> }
>>
>> /* Should not be mutable after boot, so not listed in sysfs (perm == 0). */
>> diff --git a/security/security.c b/security/security.c
>> index c4bb47d..dd792d5 100644
>> --- a/security/security.c
>> +++ b/security/security.c
>> @@ -32,6 +32,7 @@
>> /* Maximum number of letters for an LSM name string */
>> #define SECURITY_NAME_MAX 10
>>
>> +char *lsm_names;
>> /* Boot-time LSM user choice */
>> static __initdata char chosen_lsm[SECURITY_NAME_MAX + 1] =
>> CONFIG_DEFAULT_SECURITY;
>> @@ -78,6 +79,23 @@ static int __init choose_lsm(char *str)
>> }
>> __setup("security=", choose_lsm);
>>
>> +static int lsm_append(char *new, char **result)
>> +{
>> + char *cp;
>> +
>> + if (*result == NULL) {
>> + *result = kstrdup(new, GFP_KERNEL);
>> + } else {
>> + cp = kzalloc(strlen(*result) + strlen(new) + 2, GFP_KERNEL);
>> + if (cp == NULL)
>> + return -ENOMEM;
>> + sprintf(cp, "%s,%s", *result, new);
> Instead of the kzalloc+sprintf, this could be:
>
> cp = kasprintf(GFP_KERNEL, "%s,%s", *result, new);
> if (!cp)
> return -ENOMEM;
Great, I'll do it.
>
>> + kfree(*result);
>> + *result = cp;
>> + }
>> + return 0;
>> +}
>> +
>> /**
>> * security_module_enable - Load given security module on boot ?
>> * @module: the name of the module
>> @@ -97,6 +115,27 @@ int __init security_module_enable(const char *module)
>> return !strcmp(module, chosen_lsm);
>> }
>>
>> +/**
>> + * security_add_hooks - Add a modules hooks to the hook lists.
>> + * @hooks: the hooks to add
>> + * @count: the number of hooks to add
>> + * @lsm: the name of the security module
>> + *
>> + * Each LSM has to register its hooks with the infrastructure.
>> + */
>> +void __init security_add_hooks(struct security_hook_list *hooks, int count,
>> + char *lsm)
>> +{
>> + int i;
>> +
>> + for (i = 0; i < count; i++) {
>> + hooks[i].lsm = lsm;
>> + list_add_tail_rcu(&hooks[i].list, hooks[i].head);
>> + }
>> + if (lsm_append(lsm, &lsm_names) < 0)
>> + panic("%s - Cannot get early memory.\n", __func__);
>> +}
>> +
>> /*
>> * Hook list operation macros.
>> *
>> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
>> index a86d537..ed3a757 100644
>> --- a/security/selinux/hooks.c
>> +++ b/security/selinux/hooks.c
>> @@ -6233,7 +6233,7 @@ static __init int selinux_init(void)
>> 0, SLAB_PANIC, NULL);
>> avc_init();
>>
>> - security_add_hooks(selinux_hooks, ARRAY_SIZE(selinux_hooks));
>> + security_add_hooks(selinux_hooks, ARRAY_SIZE(selinux_hooks), "selinux");
>>
>> if (avc_add_callback(selinux_netcache_avc_callback, AVC_CALLBACK_RESET))
>> panic("SELinux: Unable to register AVC netcache callback\n");
>> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
>> index 6777295..3577009 100644
>> --- a/security/smack/smack_lsm.c
>> +++ b/security/smack/smack_lsm.c
>> @@ -4801,7 +4801,7 @@ static __init int smack_init(void)
>> /*
>> * Register with LSM
>> */
>> - security_add_hooks(smack_hooks, ARRAY_SIZE(smack_hooks));
>> + security_add_hooks(smack_hooks, ARRAY_SIZE(smack_hooks), "smack");
>>
>> return 0;
>> }
>> diff --git a/security/tomoyo/tomoyo.c b/security/tomoyo/tomoyo.c
>> index 75c9987..edc52d6 100644
>> --- a/security/tomoyo/tomoyo.c
>> +++ b/security/tomoyo/tomoyo.c
>> @@ -542,7 +542,7 @@ static int __init tomoyo_init(void)
>> if (!security_module_enable("tomoyo"))
>> return 0;
>> /* register ourselves with the security framework */
>> - security_add_hooks(tomoyo_hooks, ARRAY_SIZE(tomoyo_hooks));
>> + security_add_hooks(tomoyo_hooks, ARRAY_SIZE(tomoyo_hooks), "tomoyo");
>> printk(KERN_INFO "TOMOYO Linux initialized\n");
>> cred->security = &tomoyo_kernel_domain;
>> tomoyo_mm_init();
>> diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c
>> index 0309f21..f8ee60e 100644
>> --- a/security/yama/yama_lsm.c
>> +++ b/security/yama/yama_lsm.c
>> @@ -471,6 +471,6 @@ static inline void yama_init_sysctl(void) { }
>> void __init yama_add_hooks(void)
>> {
>> pr_info("Yama: becoming mindful.\n");
>> - security_add_hooks(yama_hooks, ARRAY_SIZE(yama_hooks));
>> + security_add_hooks(yama_hooks, ARRAY_SIZE(yama_hooks), "yama");
>> yama_init_sysctl();
>> }
>>
> -Kees
>
^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH v3 1/3] LSM: Add /sys/kernel/security/lsm
2016-06-10 21:25 ` [PATCH v3 1/3] LSM: Add /sys/kernel/security/lsm Casey Schaufler
2016-06-14 18:41 ` Kees Cook
@ 2016-06-14 22:25 ` David A. Wheeler
1 sibling, 0 replies; 13+ messages in thread
From: David A. Wheeler @ 2016-06-14 22:25 UTC (permalink / raw)
To: Casey Schaufler
Cc: LSM, James Morris, John Johansen, Stephen Smalley, Paul Moore,
Tetsuo Handa, Kees Cook, LKLM, James Morris
On Fri, 10 Jun 2016 14:25:45 -0700, Casey Schaufler <casey@schaufler-ca.com> wrote:
> Subject: [PATCH v3 1/3] LSM: Add /sys/kernel/security/lsm
> I got tired of having to find indirect ways to
> determine what security modules are active on a system.
> I have added /sys/kernel/security/lsm, which contains a
> comma separated list of the active security modules. No
> more groping around in /proc/filesystems, which won't
> help if the module doesn't support its own filesystem.
Great idea, thanks for doing it.
--- David A. Wheeler
^ permalink raw reply [flat|nested] 13+ messages in thread
* [PATCH v3 2/3] LSM: module hierarchy in /proc/.../attr
2016-06-10 21:21 [PATCH v3 0/3] LSM: module hierarchy in /proc/.../attr Casey Schaufler
2016-06-10 21:25 ` [PATCH v3 1/3] LSM: Add /sys/kernel/security/lsm Casey Schaufler
@ 2016-06-10 21:25 ` Casey Schaufler
2016-06-14 18:43 ` Kees Cook
2016-06-10 21:25 ` [PATCH v3 3/3] LSM: Add context interface for proc attr Casey Schaufler
2 siblings, 1 reply; 13+ messages in thread
From: Casey Schaufler @ 2016-06-10 21:25 UTC (permalink / raw)
To: LSM, James Morris
Cc: John Johansen, Stephen Smalley, Paul Moore, Tetsuo Handa,
Kees Cook, LKLM, James Morris
Subject: [PATCH v3 2/3] LSM: module hierarchy in /proc/.../attr
Back in 2007 I made what turned out to be a rather serious
mistake in the implementation of the Smack security module.
The SELinux module used an interface in /proc to manipulate
the security context on processes. Rather than use a similar
interface, I used the same interface. The AppArmor team did
likewise. Now /proc/.../attr/current will tell you the
security "context" of the process, but it will be different
depending on the security module you're using. That hasn't
been a problem to date, as you can only have one module
that supports process attributes at a time. We are coming
up on a change to that, where multiple modules with process
attributes can be supported. (Not included here)
This patch provides a subdirectory in /proc/.../attr for
each of the security modules that use the LSM hooks
getprocattr() and setprocattr(). Each of the interfaces
used by a module are presented in the subdirectory. The
old interfaces remain and work the same as before.
User space code can begin migrating to the subdirectory
interfaces in anticipation of the time when what comes
from /proc/self/attr/current might not be what a runtime
wants.
The original implementation is by Kees Cook. The code
has been changed a bit to reflect changes in the direction
of the multiple concurrent module work, to be independent
of it, and to bring it up to date with the current tree.
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
---
Documentation/security/LSM.txt | 26 +++++++++---
fs/proc/base.c | 91 +++++++++++++++++++++++++++++++++++++-----
fs/proc/internal.h | 1 +
include/linux/security.h | 15 ++++---
security/security.c | 31 ++++++++++++--
5 files changed, 140 insertions(+), 24 deletions(-)
diff --git a/Documentation/security/LSM.txt b/Documentation/security/LSM.txt
index 3db7e67..125c489 100644
--- a/Documentation/security/LSM.txt
+++ b/Documentation/security/LSM.txt
@@ -16,11 +16,25 @@ MAC extensions, other extensions can be built using the LSM to provide
specific changes to system operation when these tweaks are not available
in the core functionality of Linux itself.
-Without a specific LSM built into the kernel, the default LSM will be the
-Linux capabilities system. Most LSMs choose to extend the capabilities
-system, building their checks on top of the defined capability hooks.
-For more details on capabilities, see capabilities(7) in the Linux
-man-pages project.
+The Linux capabilities modules will always be included. For more details
+on capabilities, see capabilities(7) in the Linux man-pages project.
+This may be followed by any number of "minor" modules and at most one
+"major" module.
+
+A list of the active security modules can be found by reading
+/sys/kernel/security/lsm. This is a comma separated list, and
+will always include the capability module. The list reflects the
+order in which checks are made. The capability module will always
+be first, followed by any "minor" modules (e.g. Yama) and then
+the one "major" module (e.g. SELinux) if there is one configured.
+
+Process attributes associated with "major" security modules should
+be accessed and maintained using the special files in the module
+specific subdirectories in /proc/.../attr. The attributes related
+to Smack would be found in /proc/.../attr/smack while the attributes
+for SELinux would be in /proc/.../attr/selinux. Using the files
+found directly in /proc/.../attr (e.g. current) should be avoided.
+These files remain as legacy interfaces.
Based on https://lkml.org/lkml/2007/10/26/215,
a new LSM is accepted into the kernel when its intent (a description of
@@ -31,4 +45,4 @@ that end users and distros can make a more informed decision about which
LSMs suit their requirements.
For extensive documentation on the available LSM hook interfaces, please
-see include/linux/security.h.
+see include/linux/lsm_hooks.h.
diff --git a/fs/proc/base.c b/fs/proc/base.c
index a11eb71..182bc28 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -131,9 +131,13 @@ struct pid_entry {
#define REG(NAME, MODE, fops) \
NOD(NAME, (S_IFREG|(MODE)), NULL, &fops, {})
#define ONE(NAME, MODE, show) \
- NOD(NAME, (S_IFREG|(MODE)), \
+ NOD(NAME, (S_IFREG|(MODE)), \
NULL, &proc_single_file_operations, \
{ .proc_show = show } )
+#define ATTR(LSM, NAME, MODE) \
+ NOD(NAME, (S_IFREG|(MODE)), \
+ NULL, &proc_pid_attr_operations, \
+ { .lsm = LSM })
/*
* Count the number of hardlinks for the pid_entry table, excluding the .
@@ -2433,7 +2437,7 @@ static ssize_t proc_pid_attr_read(struct file * file, char __user * buf,
if (!task)
return -ESRCH;
- length = security_getprocattr(task,
+ length = security_getprocattr(task, PROC_I(inode)->op.lsm,
(char*)file->f_path.dentry->d_name.name,
&p);
put_task_struct(task);
@@ -2473,7 +2477,7 @@ static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf,
if (length < 0)
goto out_free;
- length = security_setprocattr(task,
+ length = security_setprocattr(task, PROC_I(inode)->op.lsm,
(char*)file->f_path.dentry->d_name.name,
page, count);
mutex_unlock(&task->signal->cred_guard_mutex);
@@ -2491,13 +2495,82 @@ static const struct file_operations proc_pid_attr_operations = {
.llseek = generic_file_llseek,
};
+#define LSM_DIR_OPS(LSM) \
+static int proc_##LSM##_attr_dir_iterate(struct file *filp, \
+ struct dir_context *ctx) \
+{ \
+ return proc_pident_readdir(filp, ctx, \
+ LSM##_attr_dir_stuff, \
+ ARRAY_SIZE(LSM##_attr_dir_stuff)); \
+} \
+\
+static const struct file_operations proc_##LSM##_attr_dir_ops = { \
+ .read = generic_read_dir, \
+ .iterate = proc_##LSM##_attr_dir_iterate, \
+ .llseek = default_llseek, \
+}; \
+\
+static struct dentry *proc_##LSM##_attr_dir_lookup(struct inode *dir, \
+ struct dentry *dentry, unsigned int flags) \
+{ \
+ return proc_pident_lookup(dir, dentry, \
+ LSM##_attr_dir_stuff, \
+ ARRAY_SIZE(LSM##_attr_dir_stuff)); \
+} \
+\
+static const struct inode_operations proc_##LSM##_attr_dir_inode_ops = { \
+ .lookup = proc_##LSM##_attr_dir_lookup, \
+ .getattr = pid_getattr, \
+ .setattr = proc_setattr, \
+}
+
+#ifdef CONFIG_SECURITY_SELINUX
+static const struct pid_entry selinux_attr_dir_stuff[] = {
+ ATTR("selinux", "current", S_IRUGO|S_IWUGO),
+ ATTR("selinux", "prev", S_IRUGO),
+ ATTR("selinux", "exec", S_IRUGO|S_IWUGO),
+ ATTR("selinux", "fscreate", S_IRUGO|S_IWUGO),
+ ATTR("selinux", "keycreate", S_IRUGO|S_IWUGO),
+ ATTR("selinux", "sockcreate", S_IRUGO|S_IWUGO),
+};
+LSM_DIR_OPS(selinux);
+#endif
+
+#ifdef CONFIG_SECURITY_SMACK
+static const struct pid_entry smack_attr_dir_stuff[] = {
+ ATTR("smack", "current", S_IRUGO|S_IWUGO),
+};
+LSM_DIR_OPS(smack);
+#endif
+
+#ifdef CONFIG_SECURITY_APPARMOR
+static const struct pid_entry apparmor_attr_dir_stuff[] = {
+ ATTR("apparmor", "current", S_IRUGO|S_IWUGO),
+ ATTR("apparmor", "prev", S_IRUGO),
+ ATTR("apparmor", "exec", S_IRUGO|S_IWUGO),
+};
+LSM_DIR_OPS(apparmor);
+#endif
+
static const struct pid_entry attr_dir_stuff[] = {
- REG("current", S_IRUGO|S_IWUGO, proc_pid_attr_operations),
- REG("prev", S_IRUGO, proc_pid_attr_operations),
- REG("exec", S_IRUGO|S_IWUGO, proc_pid_attr_operations),
- REG("fscreate", S_IRUGO|S_IWUGO, proc_pid_attr_operations),
- REG("keycreate", S_IRUGO|S_IWUGO, proc_pid_attr_operations),
- REG("sockcreate", S_IRUGO|S_IWUGO, proc_pid_attr_operations),
+ ATTR(NULL, "current", S_IRUGO|S_IWUGO),
+ ATTR(NULL, "prev", S_IRUGO),
+ ATTR(NULL, "exec", S_IRUGO|S_IWUGO),
+ ATTR(NULL, "fscreate", S_IRUGO|S_IWUGO),
+ ATTR(NULL, "keycreate", S_IRUGO|S_IWUGO),
+ ATTR(NULL, "sockcreate", S_IRUGO|S_IWUGO),
+#ifdef CONFIG_SECURITY_SELINUX
+ DIR("selinux", S_IRUGO|S_IXUGO,
+ proc_selinux_attr_dir_inode_ops, proc_selinux_attr_dir_ops),
+#endif
+#ifdef CONFIG_SECURITY_SMACK
+ DIR("smack", S_IRUGO|S_IXUGO,
+ proc_smack_attr_dir_inode_ops, proc_smack_attr_dir_ops),
+#endif
+#ifdef CONFIG_SECURITY_APPARMOR
+ DIR("apparmor", S_IRUGO|S_IXUGO,
+ proc_apparmor_attr_dir_inode_ops, proc_apparmor_attr_dir_ops),
+#endif
};
static int proc_attr_dir_readdir(struct file *file, struct dir_context *ctx)
diff --git a/fs/proc/internal.h b/fs/proc/internal.h
index aa27810..b607cd5 100644
--- a/fs/proc/internal.h
+++ b/fs/proc/internal.h
@@ -56,6 +56,7 @@ union proc_op {
int (*proc_show)(struct seq_file *m,
struct pid_namespace *ns, struct pid *pid,
struct task_struct *task);
+ const char *lsm;
};
struct proc_inode {
diff --git a/include/linux/security.h b/include/linux/security.h
index 14df373..383fcb0 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -355,8 +355,10 @@ int security_sem_semctl(struct sem_array *sma, int cmd);
int security_sem_semop(struct sem_array *sma, struct sembuf *sops,
unsigned nsops, int alter);
void security_d_instantiate(struct dentry *dentry, struct inode *inode);
-int security_getprocattr(struct task_struct *p, char *name, char **value);
-int security_setprocattr(struct task_struct *p, char *name, void *value, size_t size);
+int security_getprocattr(struct task_struct *p, const char *lsm, char *name,
+ char **value);
+int security_setprocattr(struct task_struct *p, const char *lsm, char *name,
+ void *value, size_t size);
int security_netlink_send(struct sock *sk, struct sk_buff *skb);
int security_ismaclabel(const char *name);
int security_secid_to_secctx(u32 secid, char **secdata, u32 *seclen);
@@ -1075,15 +1077,18 @@ static inline int security_sem_semop(struct sem_array *sma,
return 0;
}
-static inline void security_d_instantiate(struct dentry *dentry, struct inode *inode)
+static inline void security_d_instantiate(struct dentry *dentry,
+ struct inode *inode)
{ }
-static inline int security_getprocattr(struct task_struct *p, char *name, char **value)
+static inline int security_getprocattr(struct task_struct *p, const char *lsm,
+ char *name, char **value)
{
return -EINVAL;
}
-static inline int security_setprocattr(struct task_struct *p, char *name, void *value, size_t size)
+static inline int security_setprocattr(struct task_struct *p, const char *lsm,
+ char *name, void *value, size_t size)
{
return -EINVAL;
}
diff --git a/security/security.c b/security/security.c
index dd792d5..41ac80d 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1183,14 +1183,37 @@ void security_d_instantiate(struct dentry *dentry, struct inode *inode)
}
EXPORT_SYMBOL(security_d_instantiate);
-int security_getprocattr(struct task_struct *p, char *name, char **value)
+int security_getprocattr(struct task_struct *p, const char *lsm, char *name,
+ char **value)
{
- return call_int_hook(getprocattr, -EINVAL, p, name, value);
+ struct security_hook_list *hp;
+ int rc = -EINVAL;
+
+
+ list_for_each_entry(hp, &security_hook_heads.getprocattr, list) {
+ if (lsm != NULL && strcmp(lsm, hp->lsm))
+ continue;
+ rc = hp->hook.getprocattr(p, name, value);
+ if (rc != -ENOENT)
+ return rc;
+ }
+ return -EINVAL;
}
-int security_setprocattr(struct task_struct *p, char *name, void *value, size_t size)
+int security_setprocattr(struct task_struct *p, const char *lsm, char *name,
+ void *value, size_t size)
{
- return call_int_hook(setprocattr, -EINVAL, p, name, value, size);
+ struct security_hook_list *hp;
+ int rc = -EINVAL;
+
+ list_for_each_entry(hp, &security_hook_heads.setprocattr, list) {
+ if (lsm != NULL && strcmp(lsm, hp->lsm))
+ continue;
+ rc = hp->hook.setprocattr(p, name, value, size);
+ if (rc != -ENOENT)
+ break;
+ }
+ return rc;
}
int security_netlink_send(struct sock *sk, struct sk_buff *skb)
^ permalink raw reply related [flat|nested] 13+ messages in thread* Re: [PATCH v3 2/3] LSM: module hierarchy in /proc/.../attr
2016-06-10 21:25 ` [PATCH v3 2/3] LSM: module hierarchy in /proc/.../attr Casey Schaufler
@ 2016-06-14 18:43 ` Kees Cook
2016-06-14 19:27 ` Casey Schaufler
0 siblings, 1 reply; 13+ messages in thread
From: Kees Cook @ 2016-06-14 18:43 UTC (permalink / raw)
To: Casey Schaufler
Cc: LSM, James Morris, John Johansen, Stephen Smalley, Paul Moore,
Tetsuo Handa, LKLM, James Morris
On Fri, Jun 10, 2016 at 2:25 PM, Casey Schaufler <casey@schaufler-ca.com> wrote:
> Subject: [PATCH v3 2/3] LSM: module hierarchy in /proc/.../attr
>
> Back in 2007 I made what turned out to be a rather serious
> mistake in the implementation of the Smack security module.
> The SELinux module used an interface in /proc to manipulate
> the security context on processes. Rather than use a similar
> interface, I used the same interface. The AppArmor team did
> likewise. Now /proc/.../attr/current will tell you the
> security "context" of the process, but it will be different
> depending on the security module you're using. That hasn't
> been a problem to date, as you can only have one module
> that supports process attributes at a time. We are coming
> up on a change to that, where multiple modules with process
> attributes can be supported. (Not included here)
>
> This patch provides a subdirectory in /proc/.../attr for
> each of the security modules that use the LSM hooks
> getprocattr() and setprocattr(). Each of the interfaces
> used by a module are presented in the subdirectory. The
> old interfaces remain and work the same as before.
> User space code can begin migrating to the subdirectory
> interfaces in anticipation of the time when what comes
> from /proc/self/attr/current might not be what a runtime
> wants.
>
> The original implementation is by Kees Cook. The code
> has been changed a bit to reflect changes in the direction
> of the multiple concurrent module work, to be independent
> of it, and to bring it up to date with the current tree.
>
> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
>
> ---
> Documentation/security/LSM.txt | 26 +++++++++---
> fs/proc/base.c | 91 +++++++++++++++++++++++++++++++++++++-----
> fs/proc/internal.h | 1 +
> include/linux/security.h | 15 ++++---
> security/security.c | 31 ++++++++++++--
> 5 files changed, 140 insertions(+), 24 deletions(-)
>
> diff --git a/Documentation/security/LSM.txt b/Documentation/security/LSM.txt
> index 3db7e67..125c489 100644
> --- a/Documentation/security/LSM.txt
> +++ b/Documentation/security/LSM.txt
> @@ -16,11 +16,25 @@ MAC extensions, other extensions can be built using the LSM to provide
> specific changes to system operation when these tweaks are not available
> in the core functionality of Linux itself.
>
> -Without a specific LSM built into the kernel, the default LSM will be the
> -Linux capabilities system. Most LSMs choose to extend the capabilities
> -system, building their checks on top of the defined capability hooks.
> -For more details on capabilities, see capabilities(7) in the Linux
> -man-pages project.
> +The Linux capabilities modules will always be included. For more details
> +on capabilities, see capabilities(7) in the Linux man-pages project.
> +This may be followed by any number of "minor" modules and at most one
> +"major" module.
> +
> +A list of the active security modules can be found by reading
> +/sys/kernel/security/lsm. This is a comma separated list, and
> +will always include the capability module. The list reflects the
> +order in which checks are made. The capability module will always
> +be first, followed by any "minor" modules (e.g. Yama) and then
> +the one "major" module (e.g. SELinux) if there is one configured.
> +
> +Process attributes associated with "major" security modules should
> +be accessed and maintained using the special files in the module
> +specific subdirectories in /proc/.../attr. The attributes related
> +to Smack would be found in /proc/.../attr/smack while the attributes
> +for SELinux would be in /proc/.../attr/selinux. Using the files
> +found directly in /proc/.../attr (e.g. current) should be avoided.
> +These files remain as legacy interfaces.
>
> Based on https://lkml.org/lkml/2007/10/26/215,
> a new LSM is accepted into the kernel when its intent (a description of
> @@ -31,4 +45,4 @@ that end users and distros can make a more informed decision about which
> LSMs suit their requirements.
>
> For extensive documentation on the available LSM hook interfaces, please
> -see include/linux/security.h.
> +see include/linux/lsm_hooks.h.
> diff --git a/fs/proc/base.c b/fs/proc/base.c
> index a11eb71..182bc28 100644
> --- a/fs/proc/base.c
> +++ b/fs/proc/base.c
> @@ -131,9 +131,13 @@ struct pid_entry {
> #define REG(NAME, MODE, fops) \
> NOD(NAME, (S_IFREG|(MODE)), NULL, &fops, {})
> #define ONE(NAME, MODE, show) \
> - NOD(NAME, (S_IFREG|(MODE)), \
> + NOD(NAME, (S_IFREG|(MODE)), \
Accidental whitespace change?
> NULL, &proc_single_file_operations, \
> { .proc_show = show } )
> +#define ATTR(LSM, NAME, MODE) \
> + NOD(NAME, (S_IFREG|(MODE)), \
> + NULL, &proc_pid_attr_operations, \
> + { .lsm = LSM })
>
> /*
> * Count the number of hardlinks for the pid_entry table, excluding the .
> @@ -2433,7 +2437,7 @@ static ssize_t proc_pid_attr_read(struct file * file, char __user * buf,
> if (!task)
> return -ESRCH;
>
> - length = security_getprocattr(task,
> + length = security_getprocattr(task, PROC_I(inode)->op.lsm,
> (char*)file->f_path.dentry->d_name.name,
> &p);
> put_task_struct(task);
> @@ -2473,7 +2477,7 @@ static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf,
> if (length < 0)
> goto out_free;
>
> - length = security_setprocattr(task,
> + length = security_setprocattr(task, PROC_I(inode)->op.lsm,
> (char*)file->f_path.dentry->d_name.name,
> page, count);
> mutex_unlock(&task->signal->cred_guard_mutex);
> @@ -2491,13 +2495,82 @@ static const struct file_operations proc_pid_attr_operations = {
> .llseek = generic_file_llseek,
> };
>
> +#define LSM_DIR_OPS(LSM) \
> +static int proc_##LSM##_attr_dir_iterate(struct file *filp, \
> + struct dir_context *ctx) \
> +{ \
> + return proc_pident_readdir(filp, ctx, \
> + LSM##_attr_dir_stuff, \
> + ARRAY_SIZE(LSM##_attr_dir_stuff)); \
> +} \
> +\
> +static const struct file_operations proc_##LSM##_attr_dir_ops = { \
> + .read = generic_read_dir, \
> + .iterate = proc_##LSM##_attr_dir_iterate, \
> + .llseek = default_llseek, \
> +}; \
> +\
> +static struct dentry *proc_##LSM##_attr_dir_lookup(struct inode *dir, \
> + struct dentry *dentry, unsigned int flags) \
> +{ \
> + return proc_pident_lookup(dir, dentry, \
> + LSM##_attr_dir_stuff, \
> + ARRAY_SIZE(LSM##_attr_dir_stuff)); \
> +} \
> +\
> +static const struct inode_operations proc_##LSM##_attr_dir_inode_ops = { \
> + .lookup = proc_##LSM##_attr_dir_lookup, \
> + .getattr = pid_getattr, \
> + .setattr = proc_setattr, \
> +}
> +
> +#ifdef CONFIG_SECURITY_SELINUX
> +static const struct pid_entry selinux_attr_dir_stuff[] = {
> + ATTR("selinux", "current", S_IRUGO|S_IWUGO),
> + ATTR("selinux", "prev", S_IRUGO),
> + ATTR("selinux", "exec", S_IRUGO|S_IWUGO),
> + ATTR("selinux", "fscreate", S_IRUGO|S_IWUGO),
> + ATTR("selinux", "keycreate", S_IRUGO|S_IWUGO),
> + ATTR("selinux", "sockcreate", S_IRUGO|S_IWUGO),
> +};
> +LSM_DIR_OPS(selinux);
> +#endif
I would still prefer these be defined in the LSM instead of in a common header.
> +
> +#ifdef CONFIG_SECURITY_SMACK
> +static const struct pid_entry smack_attr_dir_stuff[] = {
> + ATTR("smack", "current", S_IRUGO|S_IWUGO),
> +};
> +LSM_DIR_OPS(smack);
> +#endif
> +
> +#ifdef CONFIG_SECURITY_APPARMOR
> +static const struct pid_entry apparmor_attr_dir_stuff[] = {
> + ATTR("apparmor", "current", S_IRUGO|S_IWUGO),
> + ATTR("apparmor", "prev", S_IRUGO),
> + ATTR("apparmor", "exec", S_IRUGO|S_IWUGO),
> +};
> +LSM_DIR_OPS(apparmor);
> +#endif
> +
> static const struct pid_entry attr_dir_stuff[] = {
> - REG("current", S_IRUGO|S_IWUGO, proc_pid_attr_operations),
> - REG("prev", S_IRUGO, proc_pid_attr_operations),
> - REG("exec", S_IRUGO|S_IWUGO, proc_pid_attr_operations),
> - REG("fscreate", S_IRUGO|S_IWUGO, proc_pid_attr_operations),
> - REG("keycreate", S_IRUGO|S_IWUGO, proc_pid_attr_operations),
> - REG("sockcreate", S_IRUGO|S_IWUGO, proc_pid_attr_operations),
> + ATTR(NULL, "current", S_IRUGO|S_IWUGO),
> + ATTR(NULL, "prev", S_IRUGO),
> + ATTR(NULL, "exec", S_IRUGO|S_IWUGO),
> + ATTR(NULL, "fscreate", S_IRUGO|S_IWUGO),
> + ATTR(NULL, "keycreate", S_IRUGO|S_IWUGO),
> + ATTR(NULL, "sockcreate", S_IRUGO|S_IWUGO),
> +#ifdef CONFIG_SECURITY_SELINUX
> + DIR("selinux", S_IRUGO|S_IXUGO,
> + proc_selinux_attr_dir_inode_ops, proc_selinux_attr_dir_ops),
> +#endif
> +#ifdef CONFIG_SECURITY_SMACK
> + DIR("smack", S_IRUGO|S_IXUGO,
> + proc_smack_attr_dir_inode_ops, proc_smack_attr_dir_ops),
> +#endif
> +#ifdef CONFIG_SECURITY_APPARMOR
> + DIR("apparmor", S_IRUGO|S_IXUGO,
> + proc_apparmor_attr_dir_inode_ops, proc_apparmor_attr_dir_ops),
> +#endif
> };
>
> static int proc_attr_dir_readdir(struct file *file, struct dir_context *ctx)
> diff --git a/fs/proc/internal.h b/fs/proc/internal.h
> index aa27810..b607cd5 100644
> --- a/fs/proc/internal.h
> +++ b/fs/proc/internal.h
> @@ -56,6 +56,7 @@ union proc_op {
> int (*proc_show)(struct seq_file *m,
> struct pid_namespace *ns, struct pid *pid,
> struct task_struct *task);
> + const char *lsm;
> };
>
> struct proc_inode {
> diff --git a/include/linux/security.h b/include/linux/security.h
> index 14df373..383fcb0 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -355,8 +355,10 @@ int security_sem_semctl(struct sem_array *sma, int cmd);
> int security_sem_semop(struct sem_array *sma, struct sembuf *sops,
> unsigned nsops, int alter);
> void security_d_instantiate(struct dentry *dentry, struct inode *inode);
> -int security_getprocattr(struct task_struct *p, char *name, char **value);
> -int security_setprocattr(struct task_struct *p, char *name, void *value, size_t size);
> +int security_getprocattr(struct task_struct *p, const char *lsm, char *name,
> + char **value);
> +int security_setprocattr(struct task_struct *p, const char *lsm, char *name,
> + void *value, size_t size);
> int security_netlink_send(struct sock *sk, struct sk_buff *skb);
> int security_ismaclabel(const char *name);
> int security_secid_to_secctx(u32 secid, char **secdata, u32 *seclen);
> @@ -1075,15 +1077,18 @@ static inline int security_sem_semop(struct sem_array *sma,
> return 0;
> }
>
> -static inline void security_d_instantiate(struct dentry *dentry, struct inode *inode)
> +static inline void security_d_instantiate(struct dentry *dentry,
> + struct inode *inode)
> { }
>
> -static inline int security_getprocattr(struct task_struct *p, char *name, char **value)
> +static inline int security_getprocattr(struct task_struct *p, const char *lsm,
> + char *name, char **value)
> {
> return -EINVAL;
> }
>
> -static inline int security_setprocattr(struct task_struct *p, char *name, void *value, size_t size)
> +static inline int security_setprocattr(struct task_struct *p, const char *lsm,
> + char *name, void *value, size_t size)
> {
> return -EINVAL;
> }
> diff --git a/security/security.c b/security/security.c
> index dd792d5..41ac80d 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -1183,14 +1183,37 @@ void security_d_instantiate(struct dentry *dentry, struct inode *inode)
> }
> EXPORT_SYMBOL(security_d_instantiate);
>
> -int security_getprocattr(struct task_struct *p, char *name, char **value)
> +int security_getprocattr(struct task_struct *p, const char *lsm, char *name,
> + char **value)
> {
> - return call_int_hook(getprocattr, -EINVAL, p, name, value);
> + struct security_hook_list *hp;
> + int rc = -EINVAL;
> +
> +
> + list_for_each_entry(hp, &security_hook_heads.getprocattr, list) {
> + if (lsm != NULL && strcmp(lsm, hp->lsm))
> + continue;
> + rc = hp->hook.getprocattr(p, name, value);
> + if (rc != -ENOENT)
> + return rc;
> + }
> + return -EINVAL;
> }
>
> -int security_setprocattr(struct task_struct *p, char *name, void *value, size_t size)
> +int security_setprocattr(struct task_struct *p, const char *lsm, char *name,
> + void *value, size_t size)
> {
> - return call_int_hook(setprocattr, -EINVAL, p, name, value, size);
> + struct security_hook_list *hp;
> + int rc = -EINVAL;
> +
> + list_for_each_entry(hp, &security_hook_heads.setprocattr, list) {
> + if (lsm != NULL && strcmp(lsm, hp->lsm))
> + continue;
> + rc = hp->hook.setprocattr(p, name, value, size);
> + if (rc != -ENOENT)
> + break;
> + }
> + return rc;
> }
>
> int security_netlink_send(struct sock *sk, struct sk_buff *skb)
>
With those changes, I'd like it. :)
-Kees
--
Kees Cook
Chrome OS & Brillo Security
^ permalink raw reply [flat|nested] 13+ messages in thread* Re: [PATCH v3 2/3] LSM: module hierarchy in /proc/.../attr
2016-06-14 18:43 ` Kees Cook
@ 2016-06-14 19:27 ` Casey Schaufler
2016-06-14 21:24 ` Kees Cook
0 siblings, 1 reply; 13+ messages in thread
From: Casey Schaufler @ 2016-06-14 19:27 UTC (permalink / raw)
To: Kees Cook
Cc: LSM, James Morris, John Johansen, Stephen Smalley, Paul Moore,
Tetsuo Handa, LKLM, James Morris
On 6/14/2016 11:43 AM, Kees Cook wrote:
> On Fri, Jun 10, 2016 at 2:25 PM, Casey Schaufler <casey@schaufler-ca.com> wrote:
>> Subject: [PATCH v3 2/3] LSM: module hierarchy in /proc/.../attr
>>
>> Back in 2007 I made what turned out to be a rather serious
>> mistake in the implementation of the Smack security module.
>> The SELinux module used an interface in /proc to manipulate
>> the security context on processes. Rather than use a similar
>> interface, I used the same interface. The AppArmor team did
>> likewise. Now /proc/.../attr/current will tell you the
>> security "context" of the process, but it will be different
>> depending on the security module you're using. That hasn't
>> been a problem to date, as you can only have one module
>> that supports process attributes at a time. We are coming
>> up on a change to that, where multiple modules with process
>> attributes can be supported. (Not included here)
>>
>> This patch provides a subdirectory in /proc/.../attr for
>> each of the security modules that use the LSM hooks
>> getprocattr() and setprocattr(). Each of the interfaces
>> used by a module are presented in the subdirectory. The
>> old interfaces remain and work the same as before.
>> User space code can begin migrating to the subdirectory
>> interfaces in anticipation of the time when what comes
>> from /proc/self/attr/current might not be what a runtime
>> wants.
>>
>> The original implementation is by Kees Cook. The code
>> has been changed a bit to reflect changes in the direction
>> of the multiple concurrent module work, to be independent
>> of it, and to bring it up to date with the current tree.
>>
>> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
>>
>> ---
>> Documentation/security/LSM.txt | 26 +++++++++---
>> fs/proc/base.c | 91 +++++++++++++++++++++++++++++++++++++-----
>> fs/proc/internal.h | 1 +
>> include/linux/security.h | 15 ++++---
>> security/security.c | 31 ++++++++++++--
>> 5 files changed, 140 insertions(+), 24 deletions(-)
>>
>> diff --git a/Documentation/security/LSM.txt b/Documentation/security/LSM.txt
>> index 3db7e67..125c489 100644
>> --- a/Documentation/security/LSM.txt
>> +++ b/Documentation/security/LSM.txt
>> @@ -16,11 +16,25 @@ MAC extensions, other extensions can be built using the LSM to provide
>> specific changes to system operation when these tweaks are not available
>> in the core functionality of Linux itself.
>>
>> -Without a specific LSM built into the kernel, the default LSM will be the
>> -Linux capabilities system. Most LSMs choose to extend the capabilities
>> -system, building their checks on top of the defined capability hooks.
>> -For more details on capabilities, see capabilities(7) in the Linux
>> -man-pages project.
>> +The Linux capabilities modules will always be included. For more details
>> +on capabilities, see capabilities(7) in the Linux man-pages project.
>> +This may be followed by any number of "minor" modules and at most one
>> +"major" module.
>> +
>> +A list of the active security modules can be found by reading
>> +/sys/kernel/security/lsm. This is a comma separated list, and
>> +will always include the capability module. The list reflects the
>> +order in which checks are made. The capability module will always
>> +be first, followed by any "minor" modules (e.g. Yama) and then
>> +the one "major" module (e.g. SELinux) if there is one configured.
>> +
>> +Process attributes associated with "major" security modules should
>> +be accessed and maintained using the special files in the module
>> +specific subdirectories in /proc/.../attr. The attributes related
>> +to Smack would be found in /proc/.../attr/smack while the attributes
>> +for SELinux would be in /proc/.../attr/selinux. Using the files
>> +found directly in /proc/.../attr (e.g. current) should be avoided.
>> +These files remain as legacy interfaces.
>>
>> Based on https://lkml.org/lkml/2007/10/26/215,
>> a new LSM is accepted into the kernel when its intent (a description of
>> @@ -31,4 +45,4 @@ that end users and distros can make a more informed decision about which
>> LSMs suit their requirements.
>>
>> For extensive documentation on the available LSM hook interfaces, please
>> -see include/linux/security.h.
>> +see include/linux/lsm_hooks.h.
>> diff --git a/fs/proc/base.c b/fs/proc/base.c
>> index a11eb71..182bc28 100644
>> --- a/fs/proc/base.c
>> +++ b/fs/proc/base.c
>> @@ -131,9 +131,13 @@ struct pid_entry {
>> #define REG(NAME, MODE, fops) \
>> NOD(NAME, (S_IFREG|(MODE)), NULL, &fops, {})
>> #define ONE(NAME, MODE, show) \
>> - NOD(NAME, (S_IFREG|(MODE)), \
>> + NOD(NAME, (S_IFREG|(MODE)), \
> Accidental whitespace change?
Space before a tab. checkpatch.pl was moaning about it.
>> NULL, &proc_single_file_operations, \
>> { .proc_show = show } )
>> +#define ATTR(LSM, NAME, MODE) \
>> + NOD(NAME, (S_IFREG|(MODE)), \
>> + NULL, &proc_pid_attr_operations, \
>> + { .lsm = LSM })
>>
>> /*
>> * Count the number of hardlinks for the pid_entry table, excluding the .
>> @@ -2433,7 +2437,7 @@ static ssize_t proc_pid_attr_read(struct file * file, char __user * buf,
>> if (!task)
>> return -ESRCH;
>>
>> - length = security_getprocattr(task,
>> + length = security_getprocattr(task, PROC_I(inode)->op.lsm,
>> (char*)file->f_path.dentry->d_name.name,
>> &p);
>> put_task_struct(task);
>> @@ -2473,7 +2477,7 @@ static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf,
>> if (length < 0)
>> goto out_free;
>>
>> - length = security_setprocattr(task,
>> + length = security_setprocattr(task, PROC_I(inode)->op.lsm,
>> (char*)file->f_path.dentry->d_name.name,
>> page, count);
>> mutex_unlock(&task->signal->cred_guard_mutex);
>> @@ -2491,13 +2495,82 @@ static const struct file_operations proc_pid_attr_operations = {
>> .llseek = generic_file_llseek,
>> };
>>
>> +#define LSM_DIR_OPS(LSM) \
>> +static int proc_##LSM##_attr_dir_iterate(struct file *filp, \
>> + struct dir_context *ctx) \
>> +{ \
>> + return proc_pident_readdir(filp, ctx, \
>> + LSM##_attr_dir_stuff, \
>> + ARRAY_SIZE(LSM##_attr_dir_stuff)); \
>> +} \
>> +\
>> +static const struct file_operations proc_##LSM##_attr_dir_ops = { \
>> + .read = generic_read_dir, \
>> + .iterate = proc_##LSM##_attr_dir_iterate, \
>> + .llseek = default_llseek, \
>> +}; \
>> +\
>> +static struct dentry *proc_##LSM##_attr_dir_lookup(struct inode *dir, \
>> + struct dentry *dentry, unsigned int flags) \
>> +{ \
>> + return proc_pident_lookup(dir, dentry, \
>> + LSM##_attr_dir_stuff, \
>> + ARRAY_SIZE(LSM##_attr_dir_stuff)); \
>> +} \
>> +\
>> +static const struct inode_operations proc_##LSM##_attr_dir_inode_ops = { \
>> + .lookup = proc_##LSM##_attr_dir_lookup, \
>> + .getattr = pid_getattr, \
>> + .setattr = proc_setattr, \
>> +}
>> +
>> +#ifdef CONFIG_SECURITY_SELINUX
>> +static const struct pid_entry selinux_attr_dir_stuff[] = {
>> + ATTR("selinux", "current", S_IRUGO|S_IWUGO),
>> + ATTR("selinux", "prev", S_IRUGO),
>> + ATTR("selinux", "exec", S_IRUGO|S_IWUGO),
>> + ATTR("selinux", "fscreate", S_IRUGO|S_IWUGO),
>> + ATTR("selinux", "keycreate", S_IRUGO|S_IWUGO),
>> + ATTR("selinux", "sockcreate", S_IRUGO|S_IWUGO),
>> +};
>> +LSM_DIR_OPS(selinux);
>> +#endif
> I would still prefer these be defined in the LSM instead of in a common header.
I am open to suggestions on how to accomplish that.
>> +
>> +#ifdef CONFIG_SECURITY_SMACK
>> +static const struct pid_entry smack_attr_dir_stuff[] = {
>> + ATTR("smack", "current", S_IRUGO|S_IWUGO),
>> +};
>> +LSM_DIR_OPS(smack);
>> +#endif
>> +
>> +#ifdef CONFIG_SECURITY_APPARMOR
>> +static const struct pid_entry apparmor_attr_dir_stuff[] = {
>> + ATTR("apparmor", "current", S_IRUGO|S_IWUGO),
>> + ATTR("apparmor", "prev", S_IRUGO),
>> + ATTR("apparmor", "exec", S_IRUGO|S_IWUGO),
>> +};
>> +LSM_DIR_OPS(apparmor);
>> +#endif
>> +
>> static const struct pid_entry attr_dir_stuff[] = {
>> - REG("current", S_IRUGO|S_IWUGO, proc_pid_attr_operations),
>> - REG("prev", S_IRUGO, proc_pid_attr_operations),
>> - REG("exec", S_IRUGO|S_IWUGO, proc_pid_attr_operations),
>> - REG("fscreate", S_IRUGO|S_IWUGO, proc_pid_attr_operations),
>> - REG("keycreate", S_IRUGO|S_IWUGO, proc_pid_attr_operations),
>> - REG("sockcreate", S_IRUGO|S_IWUGO, proc_pid_attr_operations),
>> + ATTR(NULL, "current", S_IRUGO|S_IWUGO),
>> + ATTR(NULL, "prev", S_IRUGO),
>> + ATTR(NULL, "exec", S_IRUGO|S_IWUGO),
>> + ATTR(NULL, "fscreate", S_IRUGO|S_IWUGO),
>> + ATTR(NULL, "keycreate", S_IRUGO|S_IWUGO),
>> + ATTR(NULL, "sockcreate", S_IRUGO|S_IWUGO),
>> +#ifdef CONFIG_SECURITY_SELINUX
>> + DIR("selinux", S_IRUGO|S_IXUGO,
>> + proc_selinux_attr_dir_inode_ops, proc_selinux_attr_dir_ops),
>> +#endif
>> +#ifdef CONFIG_SECURITY_SMACK
>> + DIR("smack", S_IRUGO|S_IXUGO,
>> + proc_smack_attr_dir_inode_ops, proc_smack_attr_dir_ops),
>> +#endif
>> +#ifdef CONFIG_SECURITY_APPARMOR
>> + DIR("apparmor", S_IRUGO|S_IXUGO,
>> + proc_apparmor_attr_dir_inode_ops, proc_apparmor_attr_dir_ops),
>> +#endif
>> };
>>
>> static int proc_attr_dir_readdir(struct file *file, struct dir_context *ctx)
>> diff --git a/fs/proc/internal.h b/fs/proc/internal.h
>> index aa27810..b607cd5 100644
>> --- a/fs/proc/internal.h
>> +++ b/fs/proc/internal.h
>> @@ -56,6 +56,7 @@ union proc_op {
>> int (*proc_show)(struct seq_file *m,
>> struct pid_namespace *ns, struct pid *pid,
>> struct task_struct *task);
>> + const char *lsm;
>> };
>>
>> struct proc_inode {
>> diff --git a/include/linux/security.h b/include/linux/security.h
>> index 14df373..383fcb0 100644
>> --- a/include/linux/security.h
>> +++ b/include/linux/security.h
>> @@ -355,8 +355,10 @@ int security_sem_semctl(struct sem_array *sma, int cmd);
>> int security_sem_semop(struct sem_array *sma, struct sembuf *sops,
>> unsigned nsops, int alter);
>> void security_d_instantiate(struct dentry *dentry, struct inode *inode);
>> -int security_getprocattr(struct task_struct *p, char *name, char **value);
>> -int security_setprocattr(struct task_struct *p, char *name, void *value, size_t size);
>> +int security_getprocattr(struct task_struct *p, const char *lsm, char *name,
>> + char **value);
>> +int security_setprocattr(struct task_struct *p, const char *lsm, char *name,
>> + void *value, size_t size);
>> int security_netlink_send(struct sock *sk, struct sk_buff *skb);
>> int security_ismaclabel(const char *name);
>> int security_secid_to_secctx(u32 secid, char **secdata, u32 *seclen);
>> @@ -1075,15 +1077,18 @@ static inline int security_sem_semop(struct sem_array *sma,
>> return 0;
>> }
>>
>> -static inline void security_d_instantiate(struct dentry *dentry, struct inode *inode)
>> +static inline void security_d_instantiate(struct dentry *dentry,
>> + struct inode *inode)
>> { }
>>
>> -static inline int security_getprocattr(struct task_struct *p, char *name, char **value)
>> +static inline int security_getprocattr(struct task_struct *p, const char *lsm,
>> + char *name, char **value)
>> {
>> return -EINVAL;
>> }
>>
>> -static inline int security_setprocattr(struct task_struct *p, char *name, void *value, size_t size)
>> +static inline int security_setprocattr(struct task_struct *p, const char *lsm,
>> + char *name, void *value, size_t size)
>> {
>> return -EINVAL;
>> }
>> diff --git a/security/security.c b/security/security.c
>> index dd792d5..41ac80d 100644
>> --- a/security/security.c
>> +++ b/security/security.c
>> @@ -1183,14 +1183,37 @@ void security_d_instantiate(struct dentry *dentry, struct inode *inode)
>> }
>> EXPORT_SYMBOL(security_d_instantiate);
>>
>> -int security_getprocattr(struct task_struct *p, char *name, char **value)
>> +int security_getprocattr(struct task_struct *p, const char *lsm, char *name,
>> + char **value)
>> {
>> - return call_int_hook(getprocattr, -EINVAL, p, name, value);
>> + struct security_hook_list *hp;
>> + int rc = -EINVAL;
>> +
>> +
>> + list_for_each_entry(hp, &security_hook_heads.getprocattr, list) {
>> + if (lsm != NULL && strcmp(lsm, hp->lsm))
>> + continue;
>> + rc = hp->hook.getprocattr(p, name, value);
>> + if (rc != -ENOENT)
>> + return rc;
>> + }
>> + return -EINVAL;
>> }
>>
>> -int security_setprocattr(struct task_struct *p, char *name, void *value, size_t size)
>> +int security_setprocattr(struct task_struct *p, const char *lsm, char *name,
>> + void *value, size_t size)
>> {
>> - return call_int_hook(setprocattr, -EINVAL, p, name, value, size);
>> + struct security_hook_list *hp;
>> + int rc = -EINVAL;
>> +
>> + list_for_each_entry(hp, &security_hook_heads.setprocattr, list) {
>> + if (lsm != NULL && strcmp(lsm, hp->lsm))
>> + continue;
>> + rc = hp->hook.setprocattr(p, name, value, size);
>> + if (rc != -ENOENT)
>> + break;
>> + }
>> + return rc;
>> }
>>
>> int security_netlink_send(struct sock *sk, struct sk_buff *skb)
>>
> With those changes, I'd like it. :)
>
> -Kees
>
^ permalink raw reply [flat|nested] 13+ messages in thread* Re: [PATCH v3 2/3] LSM: module hierarchy in /proc/.../attr
2016-06-14 19:27 ` Casey Schaufler
@ 2016-06-14 21:24 ` Kees Cook
0 siblings, 0 replies; 13+ messages in thread
From: Kees Cook @ 2016-06-14 21:24 UTC (permalink / raw)
To: Casey Schaufler
Cc: LSM, James Morris, John Johansen, Stephen Smalley, Paul Moore,
Tetsuo Handa, LKLM, James Morris
On Tue, Jun 14, 2016 at 12:27 PM, Casey Schaufler
<casey@schaufler-ca.com> wrote:
> On 6/14/2016 11:43 AM, Kees Cook wrote:
>> On Fri, Jun 10, 2016 at 2:25 PM, Casey Schaufler <casey@schaufler-ca.com> wrote:
>>> Subject: [PATCH v3 2/3] LSM: module hierarchy in /proc/.../attr
>>>
>>> Back in 2007 I made what turned out to be a rather serious
>>> mistake in the implementation of the Smack security module.
>>> The SELinux module used an interface in /proc to manipulate
>>> the security context on processes. Rather than use a similar
>>> interface, I used the same interface. The AppArmor team did
>>> likewise. Now /proc/.../attr/current will tell you the
>>> security "context" of the process, but it will be different
>>> depending on the security module you're using. That hasn't
>>> been a problem to date, as you can only have one module
>>> that supports process attributes at a time. We are coming
>>> up on a change to that, where multiple modules with process
>>> attributes can be supported. (Not included here)
>>>
>>> This patch provides a subdirectory in /proc/.../attr for
>>> each of the security modules that use the LSM hooks
>>> getprocattr() and setprocattr(). Each of the interfaces
>>> used by a module are presented in the subdirectory. The
>>> old interfaces remain and work the same as before.
>>> User space code can begin migrating to the subdirectory
>>> interfaces in anticipation of the time when what comes
>>> from /proc/self/attr/current might not be what a runtime
>>> wants.
>>>
>>> The original implementation is by Kees Cook. The code
>>> has been changed a bit to reflect changes in the direction
>>> of the multiple concurrent module work, to be independent
>>> of it, and to bring it up to date with the current tree.
>>>
>>> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
>>> [...]
>>> diff --git a/fs/proc/base.c b/fs/proc/base.c
>>> index a11eb71..182bc28 100644
>>> --- a/fs/proc/base.c
>>> +++ b/fs/proc/base.c
>>> @@ -131,9 +131,13 @@ struct pid_entry {
>>> #define REG(NAME, MODE, fops) \
>>> NOD(NAME, (S_IFREG|(MODE)), NULL, &fops, {})
>>> #define ONE(NAME, MODE, show) \
>>> - NOD(NAME, (S_IFREG|(MODE)), \
>>> + NOD(NAME, (S_IFREG|(MODE)), \
>> Accidental whitespace change?
>
> Space before a tab. checkpatch.pl was moaning about it.
Gotcha.
>
>>> NULL, &proc_single_file_operations, \
>>> { .proc_show = show } )
>>> +#define ATTR(LSM, NAME, MODE) \
>>> + NOD(NAME, (S_IFREG|(MODE)), \
>>> + NULL, &proc_pid_attr_operations, \
>>> + { .lsm = LSM })
>>>
>>> /*
>>> * Count the number of hardlinks for the pid_entry table, excluding the .
>>> @@ -2433,7 +2437,7 @@ static ssize_t proc_pid_attr_read(struct file * file, char __user * buf,
>>> if (!task)
>>> return -ESRCH;
>>>
>>> - length = security_getprocattr(task,
>>> + length = security_getprocattr(task, PROC_I(inode)->op.lsm,
>>> (char*)file->f_path.dentry->d_name.name,
>>> &p);
>>> put_task_struct(task);
>>> @@ -2473,7 +2477,7 @@ static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf,
>>> if (length < 0)
>>> goto out_free;
>>>
>>> - length = security_setprocattr(task,
>>> + length = security_setprocattr(task, PROC_I(inode)->op.lsm,
>>> (char*)file->f_path.dentry->d_name.name,
>>> page, count);
>>> mutex_unlock(&task->signal->cred_guard_mutex);
>>> @@ -2491,13 +2495,82 @@ static const struct file_operations proc_pid_attr_operations = {
>>> .llseek = generic_file_llseek,
>>> };
>>>
>>> +#define LSM_DIR_OPS(LSM) \
>>> +static int proc_##LSM##_attr_dir_iterate(struct file *filp, \
>>> + struct dir_context *ctx) \
>>> +{ \
>>> + return proc_pident_readdir(filp, ctx, \
>>> + LSM##_attr_dir_stuff, \
>>> + ARRAY_SIZE(LSM##_attr_dir_stuff)); \
>>> +} \
>>> +\
>>> +static const struct file_operations proc_##LSM##_attr_dir_ops = { \
>>> + .read = generic_read_dir, \
>>> + .iterate = proc_##LSM##_attr_dir_iterate, \
>>> + .llseek = default_llseek, \
>>> +}; \
>>> +\
>>> +static struct dentry *proc_##LSM##_attr_dir_lookup(struct inode *dir, \
>>> + struct dentry *dentry, unsigned int flags) \
>>> +{ \
>>> + return proc_pident_lookup(dir, dentry, \
>>> + LSM##_attr_dir_stuff, \
>>> + ARRAY_SIZE(LSM##_attr_dir_stuff)); \
>>> +} \
>>> +\
>>> +static const struct inode_operations proc_##LSM##_attr_dir_inode_ops = { \
>>> + .lookup = proc_##LSM##_attr_dir_lookup, \
>>> + .getattr = pid_getattr, \
>>> + .setattr = proc_setattr, \
>>> +}
>>> +
>>> +#ifdef CONFIG_SECURITY_SELINUX
>>> +static const struct pid_entry selinux_attr_dir_stuff[] = {
>>> + ATTR("selinux", "current", S_IRUGO|S_IWUGO),
>>> + ATTR("selinux", "prev", S_IRUGO),
>>> + ATTR("selinux", "exec", S_IRUGO|S_IWUGO),
>>> + ATTR("selinux", "fscreate", S_IRUGO|S_IWUGO),
>>> + ATTR("selinux", "keycreate", S_IRUGO|S_IWUGO),
>>> + ATTR("selinux", "sockcreate", S_IRUGO|S_IWUGO),
>>> +};
>>> +LSM_DIR_OPS(selinux);
>>> +#endif
>> I would still prefer these be defined in the LSM instead of in a common header.
>
> I am open to suggestions on how to accomplish that.
Okay, after reading through this code more, I'm convinced. Doing this
dynamically looks needlessly hard right now. :)
-Kees
--
Kees Cook
Chrome OS & Brillo Security
^ permalink raw reply [flat|nested] 13+ messages in thread
* [PATCH v3 3/3] LSM: Add context interface for proc attr
2016-06-10 21:21 [PATCH v3 0/3] LSM: module hierarchy in /proc/.../attr Casey Schaufler
2016-06-10 21:25 ` [PATCH v3 1/3] LSM: Add /sys/kernel/security/lsm Casey Schaufler
2016-06-10 21:25 ` [PATCH v3 2/3] LSM: module hierarchy in /proc/.../attr Casey Schaufler
@ 2016-06-10 21:25 ` Casey Schaufler
2016-06-14 18:57 ` Kees Cook
2 siblings, 1 reply; 13+ messages in thread
From: Casey Schaufler @ 2016-06-10 21:25 UTC (permalink / raw)
To: LSM, James Morris
Cc: John Johansen, Stephen Smalley, Paul Moore, Tetsuo Handa,
Kees Cook, LKLM, James Morris
Subject: [PATCH v3 3/3] LSM: Add context interface for proc attrs
The /proc/.../attr/current interface is used by all three
Linux security modules (SELinux, Smack and AppArmor) to
report and modify the process security attribute. This is
all fine when there is exactly one of these modules active
and the userspace code knows which it module it is.
It would require a major change to the "current" interface
to provide information about more than one set of process
security attributes. Instead, a "context" attribute is
added, which identifies the security module that the
information applies to. The format is:
lsmname='context-value'
When multiple concurrent modules are supported the
/proc/.../attr/context interface will include the data
for all of the active modules.
lsmname1='context-value1'lsmname2='context-value2'
The module specific subdirectories under attr contain context
entries that report the information for that specific module
in the same format.
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
---
fs/proc/base.c | 4 ++
security/apparmor/lsm.c | 34 ++++++++++++++--
security/security.c | 97 ++++++++++++++++++++++++++++++++++++++++++++++
security/selinux/hooks.c | 22 ++++++++++-
security/smack/smack_lsm.c | 21 ++++++----
5 files changed, 164 insertions(+), 14 deletions(-)
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 182bc28..df94f26 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2532,6 +2532,7 @@ static const struct pid_entry selinux_attr_dir_stuff[] = {
ATTR("selinux", "fscreate", S_IRUGO|S_IWUGO),
ATTR("selinux", "keycreate", S_IRUGO|S_IWUGO),
ATTR("selinux", "sockcreate", S_IRUGO|S_IWUGO),
+ ATTR("selinux", "context", S_IRUGO|S_IWUGO),
};
LSM_DIR_OPS(selinux);
#endif
@@ -2539,6 +2540,7 @@ LSM_DIR_OPS(selinux);
#ifdef CONFIG_SECURITY_SMACK
static const struct pid_entry smack_attr_dir_stuff[] = {
ATTR("smack", "current", S_IRUGO|S_IWUGO),
+ ATTR("smack", "context", S_IRUGO|S_IWUGO),
};
LSM_DIR_OPS(smack);
#endif
@@ -2548,6 +2550,7 @@ static const struct pid_entry apparmor_attr_dir_stuff[] = {
ATTR("apparmor", "current", S_IRUGO|S_IWUGO),
ATTR("apparmor", "prev", S_IRUGO),
ATTR("apparmor", "exec", S_IRUGO|S_IWUGO),
+ ATTR("apparmor", "context", S_IRUGO|S_IWUGO),
};
LSM_DIR_OPS(apparmor);
#endif
@@ -2559,6 +2562,7 @@ static const struct pid_entry attr_dir_stuff[] = {
ATTR(NULL, "fscreate", S_IRUGO|S_IWUGO),
ATTR(NULL, "keycreate", S_IRUGO|S_IWUGO),
ATTR(NULL, "sockcreate", S_IRUGO|S_IWUGO),
+ ATTR(NULL, "context", S_IRUGO|S_IWUGO),
#ifdef CONFIG_SECURITY_SELINUX
DIR("selinux", S_IRUGO|S_IXUGO,
proc_selinux_attr_dir_inode_ops, proc_selinux_attr_dir_ops),
diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
index fb0fb03..3790a7d 100644
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c
@@ -479,6 +479,8 @@ static int apparmor_getprocattr(struct task_struct *task, char *name,
if (strcmp(name, "current") == 0)
profile = aa_get_newest_profile(cxt->profile);
+ else if (strcmp(name, "context") == 0)
+ profile = aa_get_newest_profile(cxt->profile);
else if (strcmp(name, "prev") == 0 && cxt->previous)
profile = aa_get_newest_profile(cxt->previous);
else if (strcmp(name, "exec") == 0 && cxt->onexec)
@@ -486,8 +488,29 @@ static int apparmor_getprocattr(struct task_struct *task, char *name,
else
error = -EINVAL;
- if (profile)
- error = aa_getprocattr(profile, value);
+ if (profile) {
+ if (strcmp(name, "context") == 0) {
+ char *vp;
+ char *np;
+
+ error = aa_getprocattr(profile, &vp);
+ if (error > 0) {
+ error += 12;
+ *value = kzalloc(error, GFP_KERNEL);
+ if (*value == NULL)
+ error = -ENOMEM;
+ else {
+ sprintf(*value, "apparmor='%s'", vp);
+ np = strchr(*value, '\n');
+ if (np != NULL) {
+ np[0] = '\'';
+ np[1] = '\0';
+ }
+ }
+ }
+ } else
+ error = aa_getprocattr(profile, value);
+ }
aa_put_profile(profile);
put_cred(cred);
@@ -530,7 +553,7 @@ static int apparmor_setprocattr(struct task_struct *task, char *name,
return -EINVAL;
arg_size = size - (args - (char *) value);
- if (strcmp(name, "current") == 0) {
+ if (strcmp(name, "current") == 0 || strcmp(name, "context") == 0) {
if (strcmp(command, "changehat") == 0) {
error = aa_setprocattr_changehat(args, arg_size,
!AA_DO_TEST);
@@ -552,7 +575,10 @@ static int apparmor_setprocattr(struct task_struct *task, char *name,
else
goto fail;
} else
- /* only support the "current" and "exec" process attributes */
+ /*
+ * only support the "current", context and "exec"
+ * process attributes
+ */
return -EINVAL;
if (!error)
diff --git a/security/security.c b/security/security.c
index 41ac80d..6f7ad19 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1187,8 +1187,49 @@ int security_getprocattr(struct task_struct *p, const char *lsm, char *name,
char **value)
{
struct security_hook_list *hp;
+ char *vp;
+ char *cp = NULL;
int rc = -EINVAL;
+ int trc;
+ /*
+ * "context" requires work here in addition to what
+ * the modules provide.
+ */
+ if (strcmp(name, "context") == 0) {
+ *value = NULL;
+ list_for_each_entry(hp,
+ &security_hook_heads.getprocattr, list) {
+ if (lsm != NULL && strcmp(lsm, hp->lsm))
+ continue;
+ trc = hp->hook.getprocattr(p, "context", &vp);
+ if (trc == -ENOENT)
+ continue;
+ if (trc <= 0) {
+ kfree(*value);
+ return trc;
+ }
+ rc = trc;
+ if (*value == NULL) {
+ *value = vp;
+ } else {
+ cp = kzalloc(strlen(*value) + strlen(vp) + 1,
+ GFP_KERNEL);
+ if (cp == NULL) {
+ kfree(*value);
+ kfree(vp);
+ return -ENOMEM;
+ }
+ sprintf(cp, "%s%s", *value, vp);
+ kfree(*value);
+ kfree(vp);
+ *value = cp;
+ }
+ }
+ if (rc > 0)
+ return strlen(*value);
+ return rc;
+ }
list_for_each_entry(hp, &security_hook_heads.getprocattr, list) {
if (lsm != NULL && strcmp(lsm, hp->lsm))
@@ -1205,7 +1246,63 @@ int security_setprocattr(struct task_struct *p, const char *lsm, char *name,
{
struct security_hook_list *hp;
int rc = -EINVAL;
+ char *local;
+ char *cp;
+ int slen;
+ int failed = 0;
+ /*
+ * "context" is handled directly here.
+ */
+ if (strcmp(name, "context") == 0) {
+ /*
+ * First verify that the input is acceptable.
+ * lsm1='v1'lsm2='v2'lsm3='v3'
+ *
+ * A note on the use of strncmp() below.
+ * The check is for the substring at the beginning of cp.
+ */
+ local = kzalloc(size + 1, GFP_KERNEL);
+ memcpy(local, value, size);
+ cp = local;
+ list_for_each_entry(hp, &security_hook_heads.setprocattr,
+ list) {
+ if (lsm != NULL && strcmp(lsm, hp->lsm))
+ continue;
+ slen = strlen(hp->lsm);
+ if (strncmp(cp, hp->lsm, slen))
+ goto free_out;
+ cp += slen;
+ if (cp[0] != '=' || cp[1] != '\'' || cp[2] == '\'')
+ goto free_out;
+ for (cp += 2; cp[0] != '\''; cp++)
+ if (cp[0] == '\0')
+ goto free_out;
+ cp++;
+ }
+ cp = local;
+ list_for_each_entry(hp, &security_hook_heads.setprocattr,
+ list) {
+ if (lsm != NULL && strcmp(lsm, hp->lsm))
+ continue;
+ cp += strlen(hp->lsm) + 2;
+ for (slen = 0; cp[slen] != '\''; slen++)
+ ;
+ cp[slen] = '\0';
+
+ rc = hp->hook.setprocattr(p, "context", cp, slen);
+ if (rc < 0)
+ failed = rc;
+ cp += slen + 1;
+ }
+ if (failed != 0)
+ rc = failed;
+ else
+ rc = size;
+free_out:
+ kfree(local);
+ return rc;
+ }
list_for_each_entry(hp, &security_hook_heads.setprocattr, list) {
if (lsm != NULL && strcmp(lsm, hp->lsm))
continue;
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index ed3a757..3a21c2b 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -5711,6 +5711,8 @@ static int selinux_getprocattr(struct task_struct *p,
if (!strcmp(name, "current"))
sid = __tsec->sid;
+ else if (!strcmp(name, "context"))
+ sid = __tsec->sid;
else if (!strcmp(name, "prev"))
sid = __tsec->osid;
else if (!strcmp(name, "exec"))
@@ -5728,7 +5730,21 @@ static int selinux_getprocattr(struct task_struct *p,
if (!sid)
return 0;
- error = security_sid_to_context(sid, value, &len);
+ if (strcmp(name, "context")) {
+ error = security_sid_to_context(sid, value, &len);
+ } else {
+ char *vp;
+
+ error = security_sid_to_context(sid, &vp, &len);
+ if (!error) {
+ *value = kzalloc(len + 10, GFP_KERNEL);
+ if (*value == NULL)
+ error = -ENOMEM;
+ else
+ sprintf(*value, "selinux='%s'", vp);
+ }
+ }
+
if (error)
return error;
return len;
@@ -5768,6 +5784,8 @@ static int selinux_setprocattr(struct task_struct *p,
error = current_has_perm(p, PROCESS__SETSOCKCREATE);
else if (!strcmp(name, "current"))
error = current_has_perm(p, PROCESS__SETCURRENT);
+ else if (!strcmp(name, "context"))
+ error = current_has_perm(p, PROCESS__SETCURRENT);
else
error = -EINVAL;
if (error)
@@ -5827,7 +5845,7 @@ static int selinux_setprocattr(struct task_struct *p,
tsec->keycreate_sid = sid;
} else if (!strcmp(name, "sockcreate")) {
tsec->sockcreate_sid = sid;
- } else if (!strcmp(name, "current")) {
+ } else if (!strcmp(name, "current") || !strcmp(name, "context")) {
error = -EINVAL;
if (sid == 0)
goto abort_change;
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 3577009..d2d8624 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -3576,16 +3576,21 @@ static int smack_getprocattr(struct task_struct *p, char *name, char **value)
char *cp;
int slen;
- if (strcmp(name, "current") != 0)
+ if (strcmp(name, "current") == 0) {
+ cp = kstrdup(skp->smk_known, GFP_KERNEL);
+ if (cp == NULL)
+ return -ENOMEM;
+ } else if (strcmp(name, "context") == 0) {
+ slen = strlen(skp->smk_known) + 9;
+ cp = kzalloc(slen, GFP_KERNEL);
+ if (cp == NULL)
+ return -ENOMEM;
+ sprintf(cp, "smack='%s'", skp->smk_known);
+ } else
return -EINVAL;
- cp = kstrdup(skp->smk_known, GFP_KERNEL);
- if (cp == NULL)
- return -ENOMEM;
-
- slen = strlen(cp);
*value = cp;
- return slen;
+ return strlen(cp);
}
/**
@@ -3622,7 +3627,7 @@ static int smack_setprocattr(struct task_struct *p, char *name,
if (value == NULL || size == 0 || size >= SMK_LONGLABEL)
return -EINVAL;
- if (strcmp(name, "current") != 0)
+ if (strcmp(name, "current") != 0 && strcmp(name, "context") != 0)
return -EINVAL;
skp = smk_import_entry(value, size);
^ permalink raw reply related [flat|nested] 13+ messages in thread* Re: [PATCH v3 3/3] LSM: Add context interface for proc attr
2016-06-10 21:25 ` [PATCH v3 3/3] LSM: Add context interface for proc attr Casey Schaufler
@ 2016-06-14 18:57 ` Kees Cook
2016-06-14 20:19 ` Casey Schaufler
0 siblings, 1 reply; 13+ messages in thread
From: Kees Cook @ 2016-06-14 18:57 UTC (permalink / raw)
To: Casey Schaufler
Cc: LSM, James Morris, John Johansen, Stephen Smalley, Paul Moore,
Tetsuo Handa, LKLM, James Morris
On Fri, Jun 10, 2016 at 2:25 PM, Casey Schaufler <casey@schaufler-ca.com> wrote:
> Subject: [PATCH v3 3/3] LSM: Add context interface for proc attrs
>
> The /proc/.../attr/current interface is used by all three
> Linux security modules (SELinux, Smack and AppArmor) to
> report and modify the process security attribute. This is
> all fine when there is exactly one of these modules active
> and the userspace code knows which it module it is.
> It would require a major change to the "current" interface
> to provide information about more than one set of process
> security attributes. Instead, a "context" attribute is
> added, which identifies the security module that the
> information applies to. The format is:
>
> lsmname='context-value'
>
> When multiple concurrent modules are supported the
> /proc/.../attr/context interface will include the data
> for all of the active modules.
>
> lsmname1='context-value1'lsmname2='context-value2'
For humans to read this, could we add a space between each?
>
> The module specific subdirectories under attr contain context
> entries that report the information for that specific module
> in the same format.
>
> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
>
> ---
> fs/proc/base.c | 4 ++
> security/apparmor/lsm.c | 34 ++++++++++++++--
> security/security.c | 97 ++++++++++++++++++++++++++++++++++++++++++++++
> security/selinux/hooks.c | 22 ++++++++++-
> security/smack/smack_lsm.c | 21 ++++++----
> 5 files changed, 164 insertions(+), 14 deletions(-)
>
> diff --git a/fs/proc/base.c b/fs/proc/base.c
> index 182bc28..df94f26 100644
> --- a/fs/proc/base.c
> +++ b/fs/proc/base.c
> @@ -2532,6 +2532,7 @@ static const struct pid_entry selinux_attr_dir_stuff[] = {
> ATTR("selinux", "fscreate", S_IRUGO|S_IWUGO),
> ATTR("selinux", "keycreate", S_IRUGO|S_IWUGO),
> ATTR("selinux", "sockcreate", S_IRUGO|S_IWUGO),
> + ATTR("selinux", "context", S_IRUGO|S_IWUGO),
> };
> LSM_DIR_OPS(selinux);
> #endif
> @@ -2539,6 +2540,7 @@ LSM_DIR_OPS(selinux);
> #ifdef CONFIG_SECURITY_SMACK
> static const struct pid_entry smack_attr_dir_stuff[] = {
> ATTR("smack", "current", S_IRUGO|S_IWUGO),
> + ATTR("smack", "context", S_IRUGO|S_IWUGO),
> };
> LSM_DIR_OPS(smack);
> #endif
> @@ -2548,6 +2550,7 @@ static const struct pid_entry apparmor_attr_dir_stuff[] = {
> ATTR("apparmor", "current", S_IRUGO|S_IWUGO),
> ATTR("apparmor", "prev", S_IRUGO),
> ATTR("apparmor", "exec", S_IRUGO|S_IWUGO),
> + ATTR("apparmor", "context", S_IRUGO|S_IWUGO),
> };
> LSM_DIR_OPS(apparmor);
> #endif
> @@ -2559,6 +2562,7 @@ static const struct pid_entry attr_dir_stuff[] = {
> ATTR(NULL, "fscreate", S_IRUGO|S_IWUGO),
> ATTR(NULL, "keycreate", S_IRUGO|S_IWUGO),
> ATTR(NULL, "sockcreate", S_IRUGO|S_IWUGO),
> + ATTR(NULL, "context", S_IRUGO|S_IWUGO),
> #ifdef CONFIG_SECURITY_SELINUX
> DIR("selinux", S_IRUGO|S_IXUGO,
> proc_selinux_attr_dir_inode_ops, proc_selinux_attr_dir_ops),
> diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
> index fb0fb03..3790a7d 100644
> --- a/security/apparmor/lsm.c
> +++ b/security/apparmor/lsm.c
> @@ -479,6 +479,8 @@ static int apparmor_getprocattr(struct task_struct *task, char *name,
>
> if (strcmp(name, "current") == 0)
> profile = aa_get_newest_profile(cxt->profile);
> + else if (strcmp(name, "context") == 0)
> + profile = aa_get_newest_profile(cxt->profile);
> else if (strcmp(name, "prev") == 0 && cxt->previous)
> profile = aa_get_newest_profile(cxt->previous);
> else if (strcmp(name, "exec") == 0 && cxt->onexec)
> @@ -486,8 +488,29 @@ static int apparmor_getprocattr(struct task_struct *task, char *name,
> else
> error = -EINVAL;
>
> - if (profile)
> - error = aa_getprocattr(profile, value);
> + if (profile) {
> + if (strcmp(name, "context") == 0) {
> + char *vp;
> + char *np;
> +
> + error = aa_getprocattr(profile, &vp);
> + if (error > 0) {
> + error += 12;
> + *value = kzalloc(error, GFP_KERNEL);
> + if (*value == NULL)
> + error = -ENOMEM;
> + else {
> + sprintf(*value, "apparmor='%s'", vp);
> + np = strchr(*value, '\n');
> + if (np != NULL) {
> + np[0] = '\'';
> + np[1] = '\0';
> + }
> + }
> + }
> + } else
> + error = aa_getprocattr(profile, value);
> + }
>
> aa_put_profile(profile);
> put_cred(cred);
> @@ -530,7 +553,7 @@ static int apparmor_setprocattr(struct task_struct *task, char *name,
> return -EINVAL;
>
> arg_size = size - (args - (char *) value);
> - if (strcmp(name, "current") == 0) {
> + if (strcmp(name, "current") == 0 || strcmp(name, "context") == 0) {
> if (strcmp(command, "changehat") == 0) {
> error = aa_setprocattr_changehat(args, arg_size,
> !AA_DO_TEST);
> @@ -552,7 +575,10 @@ static int apparmor_setprocattr(struct task_struct *task, char *name,
> else
> goto fail;
> } else
> - /* only support the "current" and "exec" process attributes */
> + /*
> + * only support the "current", context and "exec"
> + * process attributes
> + */
> return -EINVAL;
>
> if (!error)
> diff --git a/security/security.c b/security/security.c
> index 41ac80d..6f7ad19 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -1187,8 +1187,49 @@ int security_getprocattr(struct task_struct *p, const char *lsm, char *name,
> char **value)
> {
> struct security_hook_list *hp;
> + char *vp;
> + char *cp = NULL;
> int rc = -EINVAL;
> + int trc;
>
> + /*
> + * "context" requires work here in addition to what
> + * the modules provide.
> + */
> + if (strcmp(name, "context") == 0) {
> + *value = NULL;
> + list_for_each_entry(hp,
> + &security_hook_heads.getprocattr, list) {
> + if (lsm != NULL && strcmp(lsm, hp->lsm))
> + continue;
> + trc = hp->hook.getprocattr(p, "context", &vp);
> + if (trc == -ENOENT)
> + continue;
> + if (trc <= 0) {
> + kfree(*value);
> + return trc;
> + }
> + rc = trc;
> + if (*value == NULL) {
> + *value = vp;
> + } else {
> + cp = kzalloc(strlen(*value) + strlen(vp) + 1,
> + GFP_KERNEL);
> + if (cp == NULL) {
> + kfree(*value);
> + kfree(vp);
> + return -ENOMEM;
> + }
> + sprintf(cp, "%s%s", *value, vp);
This is another place kasprinf() would be cleaner.
> + kfree(*value);
> + kfree(vp);
> + *value = cp;
> + }
> + }
> + if (rc > 0)
> + return strlen(*value);
> + return rc;
> + }
>
> list_for_each_entry(hp, &security_hook_heads.getprocattr, list) {
> if (lsm != NULL && strcmp(lsm, hp->lsm))
> @@ -1205,7 +1246,63 @@ int security_setprocattr(struct task_struct *p, const char *lsm, char *name,
> {
> struct security_hook_list *hp;
> int rc = -EINVAL;
> + char *local;
> + char *cp;
> + int slen;
> + int failed = 0;
>
> + /*
> + * "context" is handled directly here.
> + */
> + if (strcmp(name, "context") == 0) {
> + /*
> + * First verify that the input is acceptable.
> + * lsm1='v1'lsm2='v2'lsm3='v3'
> + *
> + * A note on the use of strncmp() below.
> + * The check is for the substring at the beginning of cp.
> + */
I'd add a note that this is creating a NULL-terminated string. Though
to that end, should NULL bytes be invalid in the input string? It
could confuse things.
> + local = kzalloc(size + 1, GFP_KERNEL);
> + memcpy(local, value, size);
> + cp = local;
> + list_for_each_entry(hp, &security_hook_heads.setprocattr,
> + list) {
> + if (lsm != NULL && strcmp(lsm, hp->lsm))
> + continue;
> + slen = strlen(hp->lsm);
> + if (strncmp(cp, hp->lsm, slen))
> + goto free_out;
> + cp += slen;
> + if (cp[0] != '=' || cp[1] != '\'' || cp[2] == '\'')
> + goto free_out;
> + for (cp += 2; cp[0] != '\''; cp++)
> + if (cp[0] == '\0')
> + goto free_out;
> + cp++;
> + }
Is it okay that this loop allows unknown LSMs to be input? (I think
it's okay.) Also, should lsm == NULL be checked early and
rejected/skipped so the lsm != NULL test isn't needed in both loops?
> + cp = local;
> + list_for_each_entry(hp, &security_hook_heads.setprocattr,
> + list) {
> + if (lsm != NULL && strcmp(lsm, hp->lsm))
> + continue;
> + cp += strlen(hp->lsm) + 2;
> + for (slen = 0; cp[slen] != '\''; slen++)
> + ;
> + cp[slen] = '\0';
> +
> + rc = hp->hook.setprocattr(p, "context", cp, slen);
> + if (rc < 0)
> + failed = rc;
> + cp += slen + 1;
> + }
> + if (failed != 0)
> + rc = failed;
> + else
> + rc = size;
> +free_out:
> + kfree(local);
> + return rc;
> + }
> list_for_each_entry(hp, &security_hook_heads.setprocattr, list) {
> if (lsm != NULL && strcmp(lsm, hp->lsm))
> continue;
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index ed3a757..3a21c2b 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -5711,6 +5711,8 @@ static int selinux_getprocattr(struct task_struct *p,
>
> if (!strcmp(name, "current"))
> sid = __tsec->sid;
> + else if (!strcmp(name, "context"))
> + sid = __tsec->sid;
> else if (!strcmp(name, "prev"))
> sid = __tsec->osid;
> else if (!strcmp(name, "exec"))
> @@ -5728,7 +5730,21 @@ static int selinux_getprocattr(struct task_struct *p,
> if (!sid)
> return 0;
>
> - error = security_sid_to_context(sid, value, &len);
> + if (strcmp(name, "context")) {
> + error = security_sid_to_context(sid, value, &len);
> + } else {
> + char *vp;
> +
> + error = security_sid_to_context(sid, &vp, &len);
> + if (!error) {
> + *value = kzalloc(len + 10, GFP_KERNEL);
> + if (*value == NULL)
> + error = -ENOMEM;
> + else
> + sprintf(*value, "selinux='%s'", vp);
More kasprintf...
> + }
> + }
> +
> if (error)
> return error;
> return len;
> @@ -5768,6 +5784,8 @@ static int selinux_setprocattr(struct task_struct *p,
> error = current_has_perm(p, PROCESS__SETSOCKCREATE);
> else if (!strcmp(name, "current"))
> error = current_has_perm(p, PROCESS__SETCURRENT);
> + else if (!strcmp(name, "context"))
> + error = current_has_perm(p, PROCESS__SETCURRENT);
> else
> error = -EINVAL;
> if (error)
> @@ -5827,7 +5845,7 @@ static int selinux_setprocattr(struct task_struct *p,
> tsec->keycreate_sid = sid;
> } else if (!strcmp(name, "sockcreate")) {
> tsec->sockcreate_sid = sid;
> - } else if (!strcmp(name, "current")) {
> + } else if (!strcmp(name, "current") || !strcmp(name, "context")) {
> error = -EINVAL;
> if (sid == 0)
> goto abort_change;
> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> index 3577009..d2d8624 100644
> --- a/security/smack/smack_lsm.c
> +++ b/security/smack/smack_lsm.c
> @@ -3576,16 +3576,21 @@ static int smack_getprocattr(struct task_struct *p, char *name, char **value)
> char *cp;
> int slen;
>
> - if (strcmp(name, "current") != 0)
> + if (strcmp(name, "current") == 0) {
> + cp = kstrdup(skp->smk_known, GFP_KERNEL);
> + if (cp == NULL)
> + return -ENOMEM;
> + } else if (strcmp(name, "context") == 0) {
> + slen = strlen(skp->smk_known) + 9;
> + cp = kzalloc(slen, GFP_KERNEL);
> + if (cp == NULL)
> + return -ENOMEM;
> + sprintf(cp, "smack='%s'", skp->smk_known);
And more kasprintf
> + } else
> return -EINVAL;
>
> - cp = kstrdup(skp->smk_known, GFP_KERNEL);
> - if (cp == NULL)
> - return -ENOMEM;
> -
> - slen = strlen(cp);
> *value = cp;
> - return slen;
> + return strlen(cp);
> }
>
> /**
> @@ -3622,7 +3627,7 @@ static int smack_setprocattr(struct task_struct *p, char *name,
> if (value == NULL || size == 0 || size >= SMK_LONGLABEL)
> return -EINVAL;
>
> - if (strcmp(name, "current") != 0)
> + if (strcmp(name, "current") != 0 && strcmp(name, "context") != 0)
> return -EINVAL;
>
> skp = smk_import_entry(value, size);
>
Otherwise, looks good to me.
-Kees
--
Kees Cook
Chrome OS & Brillo Security
^ permalink raw reply [flat|nested] 13+ messages in thread* Re: [PATCH v3 3/3] LSM: Add context interface for proc attr
2016-06-14 18:57 ` Kees Cook
@ 2016-06-14 20:19 ` Casey Schaufler
2016-06-14 21:07 ` Kees Cook
0 siblings, 1 reply; 13+ messages in thread
From: Casey Schaufler @ 2016-06-14 20:19 UTC (permalink / raw)
To: Kees Cook
Cc: LSM, James Morris, John Johansen, Stephen Smalley, Paul Moore,
Tetsuo Handa, LKLM, James Morris
On 6/14/2016 11:57 AM, Kees Cook wrote:
> On Fri, Jun 10, 2016 at 2:25 PM, Casey Schaufler <casey@schaufler-ca.com> wrote:
>> Subject: [PATCH v3 3/3] LSM: Add context interface for proc attrs
>>
>> The /proc/.../attr/current interface is used by all three
>> Linux security modules (SELinux, Smack and AppArmor) to
>> report and modify the process security attribute. This is
>> all fine when there is exactly one of these modules active
>> and the userspace code knows which it module it is.
>> It would require a major change to the "current" interface
>> to provide information about more than one set of process
>> security attributes. Instead, a "context" attribute is
>> added, which identifies the security module that the
>> information applies to. The format is:
>>
>> lsmname='context-value'
>>
>> When multiple concurrent modules are supported the
>> /proc/.../attr/context interface will include the data
>> for all of the active modules.
>>
>> lsmname1='context-value1'lsmname2='context-value2'
> For humans to read this, could we add a space between each?
You can't use it in audit records or SO_PEERSEC if you
put whitespace in it.
>> The module specific subdirectories under attr contain context
>> entries that report the information for that specific module
>> in the same format.
>>
>> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
>>
>> ---
>> fs/proc/base.c | 4 ++
>> security/apparmor/lsm.c | 34 ++++++++++++++--
>> security/security.c | 97 ++++++++++++++++++++++++++++++++++++++++++++++
>> security/selinux/hooks.c | 22 ++++++++++-
>> security/smack/smack_lsm.c | 21 ++++++----
>> 5 files changed, 164 insertions(+), 14 deletions(-)
>>
>> diff --git a/fs/proc/base.c b/fs/proc/base.c
>> index 182bc28..df94f26 100644
>> --- a/fs/proc/base.c
>> +++ b/fs/proc/base.c
>> @@ -2532,6 +2532,7 @@ static const struct pid_entry selinux_attr_dir_stuff[] = {
>> ATTR("selinux", "fscreate", S_IRUGO|S_IWUGO),
>> ATTR("selinux", "keycreate", S_IRUGO|S_IWUGO),
>> ATTR("selinux", "sockcreate", S_IRUGO|S_IWUGO),
>> + ATTR("selinux", "context", S_IRUGO|S_IWUGO),
>> };
>> LSM_DIR_OPS(selinux);
>> #endif
>> @@ -2539,6 +2540,7 @@ LSM_DIR_OPS(selinux);
>> #ifdef CONFIG_SECURITY_SMACK
>> static const struct pid_entry smack_attr_dir_stuff[] = {
>> ATTR("smack", "current", S_IRUGO|S_IWUGO),
>> + ATTR("smack", "context", S_IRUGO|S_IWUGO),
>> };
>> LSM_DIR_OPS(smack);
>> #endif
>> @@ -2548,6 +2550,7 @@ static const struct pid_entry apparmor_attr_dir_stuff[] = {
>> ATTR("apparmor", "current", S_IRUGO|S_IWUGO),
>> ATTR("apparmor", "prev", S_IRUGO),
>> ATTR("apparmor", "exec", S_IRUGO|S_IWUGO),
>> + ATTR("apparmor", "context", S_IRUGO|S_IWUGO),
>> };
>> LSM_DIR_OPS(apparmor);
>> #endif
>> @@ -2559,6 +2562,7 @@ static const struct pid_entry attr_dir_stuff[] = {
>> ATTR(NULL, "fscreate", S_IRUGO|S_IWUGO),
>> ATTR(NULL, "keycreate", S_IRUGO|S_IWUGO),
>> ATTR(NULL, "sockcreate", S_IRUGO|S_IWUGO),
>> + ATTR(NULL, "context", S_IRUGO|S_IWUGO),
>> #ifdef CONFIG_SECURITY_SELINUX
>> DIR("selinux", S_IRUGO|S_IXUGO,
>> proc_selinux_attr_dir_inode_ops, proc_selinux_attr_dir_ops),
>> diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
>> index fb0fb03..3790a7d 100644
>> --- a/security/apparmor/lsm.c
>> +++ b/security/apparmor/lsm.c
>> @@ -479,6 +479,8 @@ static int apparmor_getprocattr(struct task_struct *task, char *name,
>>
>> if (strcmp(name, "current") == 0)
>> profile = aa_get_newest_profile(cxt->profile);
>> + else if (strcmp(name, "context") == 0)
>> + profile = aa_get_newest_profile(cxt->profile);
>> else if (strcmp(name, "prev") == 0 && cxt->previous)
>> profile = aa_get_newest_profile(cxt->previous);
>> else if (strcmp(name, "exec") == 0 && cxt->onexec)
>> @@ -486,8 +488,29 @@ static int apparmor_getprocattr(struct task_struct *task, char *name,
>> else
>> error = -EINVAL;
>>
>> - if (profile)
>> - error = aa_getprocattr(profile, value);
>> + if (profile) {
>> + if (strcmp(name, "context") == 0) {
>> + char *vp;
>> + char *np;
>> +
>> + error = aa_getprocattr(profile, &vp);
>> + if (error > 0) {
>> + error += 12;
>> + *value = kzalloc(error, GFP_KERNEL);
>> + if (*value == NULL)
>> + error = -ENOMEM;
>> + else {
>> + sprintf(*value, "apparmor='%s'", vp);
>> + np = strchr(*value, '\n');
>> + if (np != NULL) {
>> + np[0] = '\'';
>> + np[1] = '\0';
>> + }
>> + }
>> + }
>> + } else
>> + error = aa_getprocattr(profile, value);
>> + }
>>
>> aa_put_profile(profile);
>> put_cred(cred);
>> @@ -530,7 +553,7 @@ static int apparmor_setprocattr(struct task_struct *task, char *name,
>> return -EINVAL;
>>
>> arg_size = size - (args - (char *) value);
>> - if (strcmp(name, "current") == 0) {
>> + if (strcmp(name, "current") == 0 || strcmp(name, "context") == 0) {
>> if (strcmp(command, "changehat") == 0) {
>> error = aa_setprocattr_changehat(args, arg_size,
>> !AA_DO_TEST);
>> @@ -552,7 +575,10 @@ static int apparmor_setprocattr(struct task_struct *task, char *name,
>> else
>> goto fail;
>> } else
>> - /* only support the "current" and "exec" process attributes */
>> + /*
>> + * only support the "current", context and "exec"
>> + * process attributes
>> + */
>> return -EINVAL;
>>
>> if (!error)
>> diff --git a/security/security.c b/security/security.c
>> index 41ac80d..6f7ad19 100644
>> --- a/security/security.c
>> +++ b/security/security.c
>> @@ -1187,8 +1187,49 @@ int security_getprocattr(struct task_struct *p, const char *lsm, char *name,
>> char **value)
>> {
>> struct security_hook_list *hp;
>> + char *vp;
>> + char *cp = NULL;
>> int rc = -EINVAL;
>> + int trc;
>>
>> + /*
>> + * "context" requires work here in addition to what
>> + * the modules provide.
>> + */
>> + if (strcmp(name, "context") == 0) {
>> + *value = NULL;
>> + list_for_each_entry(hp,
>> + &security_hook_heads.getprocattr, list) {
>> + if (lsm != NULL && strcmp(lsm, hp->lsm))
>> + continue;
>> + trc = hp->hook.getprocattr(p, "context", &vp);
>> + if (trc == -ENOENT)
>> + continue;
>> + if (trc <= 0) {
>> + kfree(*value);
>> + return trc;
>> + }
>> + rc = trc;
>> + if (*value == NULL) {
>> + *value = vp;
>> + } else {
>> + cp = kzalloc(strlen(*value) + strlen(vp) + 1,
>> + GFP_KERNEL);
>> + if (cp == NULL) {
>> + kfree(*value);
>> + kfree(vp);
>> + return -ENOMEM;
>> + }
>> + sprintf(cp, "%s%s", *value, vp);
> This is another place kasprinf() would be cleaner.
Agreed. Will make the change.
>
>> + kfree(*value);
>> + kfree(vp);
>> + *value = cp;
>> + }
>> + }
>> + if (rc > 0)
>> + return strlen(*value);
>> + return rc;
>> + }
>>
>> list_for_each_entry(hp, &security_hook_heads.getprocattr, list) {
>> if (lsm != NULL && strcmp(lsm, hp->lsm))
>> @@ -1205,7 +1246,63 @@ int security_setprocattr(struct task_struct *p, const char *lsm, char *name,
>> {
>> struct security_hook_list *hp;
>> int rc = -EINVAL;
>> + char *local;
>> + char *cp;
>> + int slen;
>> + int failed = 0;
>>
>> + /*
>> + * "context" is handled directly here.
>> + */
>> + if (strcmp(name, "context") == 0) {
>> + /*
>> + * First verify that the input is acceptable.
>> + * lsm1='v1'lsm2='v2'lsm3='v3'
>> + *
>> + * A note on the use of strncmp() below.
>> + * The check is for the substring at the beginning of cp.
>> + */
> I'd add a note that this is creating a NULL-terminated string. Though
> to that end, should NULL bytes be invalid in the input string? It
> could confuse things.
>
>> + local = kzalloc(size + 1, GFP_KERNEL);
>> + memcpy(local, value, size);
>> + cp = local;
>> + list_for_each_entry(hp, &security_hook_heads.setprocattr,
>> + list) {
>> + if (lsm != NULL && strcmp(lsm, hp->lsm))
>> + continue;
>> + slen = strlen(hp->lsm);
>> + if (strncmp(cp, hp->lsm, slen))
>> + goto free_out;
>> + cp += slen;
>> + if (cp[0] != '=' || cp[1] != '\'' || cp[2] == '\'')
>> + goto free_out;
>> + for (cp += 2; cp[0] != '\''; cp++)
>> + if (cp[0] == '\0')
>> + goto free_out;
>> + cp++;
>> + }
> Is it okay that this loop allows unknown LSMs to be input? (I think
It requires that all the necessary data be supplied, and in the
correct order. Once it has it, it stops. There could be a check that
there isn't anything beyond the last entry. I'm not worried about
that.
> it's okay.) Also, should lsm == NULL be checked early and
> rejected/skipped so the lsm != NULL test isn't needed in both loops?
Ah, you miss the nuance of the code. NULL is an acceptance condition,
not a rejection as it would be in most cases.
>> + cp = local;
>> + list_for_each_entry(hp, &security_hook_heads.setprocattr,
>> + list) {
>> + if (lsm != NULL && strcmp(lsm, hp->lsm))
>> + continue;
>> + cp += strlen(hp->lsm) + 2;
>> + for (slen = 0; cp[slen] != '\''; slen++)
>> + ;
>> + cp[slen] = '\0';
>> +
>> + rc = hp->hook.setprocattr(p, "context", cp, slen);
>> + if (rc < 0)
>> + failed = rc;
>> + cp += slen + 1;
>> + }
>> + if (failed != 0)
>> + rc = failed;
>> + else
>> + rc = size;
>> +free_out:
>> + kfree(local);
>> + return rc;
>> + }
>> list_for_each_entry(hp, &security_hook_heads.setprocattr, list) {
>> if (lsm != NULL && strcmp(lsm, hp->lsm))
>> continue;
>> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
>> index ed3a757..3a21c2b 100644
>> --- a/security/selinux/hooks.c
>> +++ b/security/selinux/hooks.c
>> @@ -5711,6 +5711,8 @@ static int selinux_getprocattr(struct task_struct *p,
>>
>> if (!strcmp(name, "current"))
>> sid = __tsec->sid;
>> + else if (!strcmp(name, "context"))
>> + sid = __tsec->sid;
>> else if (!strcmp(name, "prev"))
>> sid = __tsec->osid;
>> else if (!strcmp(name, "exec"))
>> @@ -5728,7 +5730,21 @@ static int selinux_getprocattr(struct task_struct *p,
>> if (!sid)
>> return 0;
>>
>> - error = security_sid_to_context(sid, value, &len);
>> + if (strcmp(name, "context")) {
>> + error = security_sid_to_context(sid, value, &len);
>> + } else {
>> + char *vp;
>> +
>> + error = security_sid_to_context(sid, &vp, &len);
>> + if (!error) {
>> + *value = kzalloc(len + 10, GFP_KERNEL);
>> + if (*value == NULL)
>> + error = -ENOMEM;
>> + else
>> + sprintf(*value, "selinux='%s'", vp);
> More kasprintf...
Indeed.
>
>> + }
>> + }
>> +
>> if (error)
>> return error;
>> return len;
>> @@ -5768,6 +5784,8 @@ static int selinux_setprocattr(struct task_struct *p,
>> error = current_has_perm(p, PROCESS__SETSOCKCREATE);
>> else if (!strcmp(name, "current"))
>> error = current_has_perm(p, PROCESS__SETCURRENT);
>> + else if (!strcmp(name, "context"))
>> + error = current_has_perm(p, PROCESS__SETCURRENT);
>> else
>> error = -EINVAL;
>> if (error)
>> @@ -5827,7 +5845,7 @@ static int selinux_setprocattr(struct task_struct *p,
>> tsec->keycreate_sid = sid;
>> } else if (!strcmp(name, "sockcreate")) {
>> tsec->sockcreate_sid = sid;
>> - } else if (!strcmp(name, "current")) {
>> + } else if (!strcmp(name, "current") || !strcmp(name, "context")) {
>> error = -EINVAL;
>> if (sid == 0)
>> goto abort_change;
>> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
>> index 3577009..d2d8624 100644
>> --- a/security/smack/smack_lsm.c
>> +++ b/security/smack/smack_lsm.c
>> @@ -3576,16 +3576,21 @@ static int smack_getprocattr(struct task_struct *p, char *name, char **value)
>> char *cp;
>> int slen;
>>
>> - if (strcmp(name, "current") != 0)
>> + if (strcmp(name, "current") == 0) {
>> + cp = kstrdup(skp->smk_known, GFP_KERNEL);
>> + if (cp == NULL)
>> + return -ENOMEM;
>> + } else if (strcmp(name, "context") == 0) {
>> + slen = strlen(skp->smk_known) + 9;
>> + cp = kzalloc(slen, GFP_KERNEL);
>> + if (cp == NULL)
>> + return -ENOMEM;
>> + sprintf(cp, "smack='%s'", skp->smk_known);
> And more kasprintf
Yes.
>> + } else
>> return -EINVAL;
>>
>> - cp = kstrdup(skp->smk_known, GFP_KERNEL);
>> - if (cp == NULL)
>> - return -ENOMEM;
>> -
>> - slen = strlen(cp);
>> *value = cp;
>> - return slen;
>> + return strlen(cp);
>> }
>>
>> /**
>> @@ -3622,7 +3627,7 @@ static int smack_setprocattr(struct task_struct *p, char *name,
>> if (value == NULL || size == 0 || size >= SMK_LONGLABEL)
>> return -EINVAL;
>>
>> - if (strcmp(name, "current") != 0)
>> + if (strcmp(name, "current") != 0 && strcmp(name, "context") != 0)
>> return -EINVAL;
>>
>> skp = smk_import_entry(value, size);
>>
> Otherwise, looks good to me.
>
> -Kees
>
^ permalink raw reply [flat|nested] 13+ messages in thread* Re: [PATCH v3 3/3] LSM: Add context interface for proc attr
2016-06-14 20:19 ` Casey Schaufler
@ 2016-06-14 21:07 ` Kees Cook
0 siblings, 0 replies; 13+ messages in thread
From: Kees Cook @ 2016-06-14 21:07 UTC (permalink / raw)
To: Casey Schaufler
Cc: LSM, James Morris, John Johansen, Stephen Smalley, Paul Moore,
Tetsuo Handa, LKLM, James Morris
On Tue, Jun 14, 2016 at 1:19 PM, Casey Schaufler <casey@schaufler-ca.com> wrote:
> On 6/14/2016 11:57 AM, Kees Cook wrote:
>> it's okay.) Also, should lsm == NULL be checked early and
>> rejected/skipped so the lsm != NULL test isn't needed in both loops?
>
> Ah, you miss the nuance of the code. NULL is an acceptance condition,
> not a rejection as it would be in most cases.
Ah! Yes, got it now. Thanks!
-Kees
--
Kees Cook
Chrome OS & Brillo Security
^ permalink raw reply [flat|nested] 13+ messages in thread