[PATCH 1/4] security_cap_extra() and more
- Renames capable() to capable_light().
This function is used if only a capability is to be checked.
- Implement a new capable that calls security_cap_extra().
Since a subadmin has almost the same capabilities as a
superadmin, an extra helper is needed to decide whether an
action is allowed, based on the philosophy of the LSM.
- implement the .cap_extra LSM hook
Signed-off-by: Jan Engelhardt <jengelh@gmx.de>, May 01 2006
July 11 2006
---
include/linux/capability.h | 2 ++
include/linux/security.h | 13 +++++++++++++
kernel/capability.c | 19 ++++++++++++++++++-
security/dummy.c | 6 ++++++
4 files changed, 39 insertions(+), 1 deletion(-)
Index: linux-2.6.23.1/include/linux/capability.h
===================================================================
--- linux-2.6.23.1.orig/include/linux/capability.h
+++ linux-2.6.23.1/include/linux/capability.h
@@ -358,6 +358,8 @@ static inline kernel_cap_t cap_invert(ke
#define cap_is_fs_cap(c) (CAP_TO_MASK(c) & CAP_FS_MASK)
+bool capable_light(unsigned int);
+bool __capable_light(struct task_struct *, unsigned int);
int capable(int cap);
int __capable(struct task_struct *t, int cap);
Index: linux-2.6.23.1/include/linux/security.h
===================================================================
--- linux-2.6.23.1.orig/include/linux/security.h
+++ linux-2.6.23.1/include/linux/security.h
@@ -1399,6 +1399,7 @@ struct security_operations {
#endif /* CONFIG_KEYS */
+ int (*cap_extra)(struct task_struct *, unsigned int);
};
/* global variables */
@@ -2132,6 +2133,12 @@ static inline void security_release_secc
return security_ops->release_secctx(secdata, seclen);
}
+static inline int security_cap_extra(struct task_struct *task,
+ unsigned int cap)
+{
+ return security_ops->cap_extra(task, cap);
+}
+
/* prototypes */
extern int security_init (void);
extern int register_security (struct security_operations *ops);
@@ -2786,6 +2793,12 @@ static inline int security_netlink_recv
return cap_netlink_recv (skb, cap);
}
+static inline int security_cap_extra(struct task_struct *task,
+ unsigned int cap)
+{
+ return 0;
+}
+
static inline struct dentry *securityfs_create_dir(const char *name,
struct dentry *parent)
{
Index: linux-2.6.23.1/kernel/capability.c
===================================================================
--- linux-2.6.23.1.orig/kernel/capability.c
+++ linux-2.6.23.1/kernel/capability.c
@@ -238,7 +238,7 @@ out:
int __capable(struct task_struct *t, int cap)
{
- if (security_capable(t, cap) == 0) {
+ if (security_capable(t, cap) == 0 && security_cap_extra(t, cap) == 0) {
t->flags |= PF_SUPERPRIV;
return 1;
}
@@ -251,3 +251,20 @@ int capable(int cap)
return __capable(current, cap);
}
EXPORT_SYMBOL(capable);
+
+bool __capable_light(struct task_struct *t, unsigned int cap)
+{
+ if (security_capable(t, cap) == 0) {
+ t->flags |= PF_SUPERPRIV;
+ return true;
+ }
+ return false;
+}
+EXPORT_SYMBOL(__capable_light);
+
+bool capable_light(unsigned int cap)
+{
+ return __capable_light(current, cap);
+}
+EXPORT_SYMBOL(capable_light);
+
Index: linux-2.6.23.1/security/dummy.c
===================================================================
--- linux-2.6.23.1.orig/security/dummy.c
+++ linux-2.6.23.1/security/dummy.c
@@ -693,6 +693,11 @@ static int dummy_netlink_recv (struct sk
return 0;
}
+static int dummy_cap_extra(struct task_struct *task, unsigned int cap)
+{
+ return 0;
+}
+
#ifdef CONFIG_SECURITY_NETWORK
static int dummy_unix_stream_connect (struct socket *sock,
struct socket *other,
@@ -1132,5 +1137,6 @@ void security_fixup_ops (struct security
set_to_dummy_if_null(ops, key_permission);
#endif /* CONFIG_KEYS */
+ set_to_dummy_if_null(ops, cap_extra);
}
-
