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-rw-r--r--kernel/capability.c132
1 files changed, 94 insertions, 38 deletions
diff --git a/kernel/capability.c b/kernel/capability.c
index 39e8193..901e0fd 100644
--- a/kernel/capability.c
+++ b/kernel/capability.c
@@ -53,11 +53,95 @@ static void warn_legacy_capability_use(void)
}
/*
+ * Version 2 capabilities worked fine, but the linux/capability.h file
+ * that accompanied their introduction encouraged their use without
+ * the necessary user-space source code changes. As such, we have
+ * created a version 3 with equivalent functionality to version 2, but
+ * with a header change to protect legacy source code from using
+ * version 2 when it wanted to use version 1. If your system has code
+ * that trips the following warning, it is using version 2 specific
+ * capabilities and may be doing so insecurely.
+ *
+ * The remedy is to either upgrade your version of libcap (to 2.10+,
+ * if the application is linked against it), or recompile your
+ * application with modern kernel headers and this warning will go
+ * away.
+ */
+
+static void warn_deprecated_v2(void)
+{
+ static int warned;
+
+ if (!warned) {
+ char name[sizeof(current->comm)];
+
+ printk(KERN_INFO "warning: `%s' uses deprecated v2"
+ " capabilities in a way that may be insecure.\n",
+ get_task_comm(name, current));
+ warned = 1;
+ }
+}
+
+/*
+ * Version check. Return the number of u32s in each capability flag
+ * array, or a negative value on error.
+ */
+static int cap_validate_magic(cap_user_header_t header, unsigned *tocopy)
+{
+ __u32 version;
+
+ if (get_user(version, &header->version))
+ return -EFAULT;
+
+ switch (version) {
+ case _LINUX_CAPABILITY_VERSION_1:
+ warn_legacy_capability_use();
+ *tocopy = _LINUX_CAPABILITY_U32S_1;
+ break;
+ case _LINUX_CAPABILITY_VERSION_2:
+ warn_deprecated_v2();
+ /*
+ * fall through - v3 is otherwise equivalent to v2.
+ */
+ case _LINUX_CAPABILITY_VERSION_3:
+ *tocopy = _LINUX_CAPABILITY_U32S_3;
+ break;
+ default:
+ if (put_user((u32)_KERNEL_CAPABILITY_VERSION, &header->version))
+ return -EFAULT;
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+/*
* For sys_getproccap() and sys_setproccap(), any of the three
* capability set pointers may be NULL -- indicating that that set is
* uninteresting and/or not to be changed.
*/
+/*
+ * Atomically modify the effective capabilities returning the original
+ * value. No permission check is performed here - it is assumed that the
+ * caller is permitted to set the desired effective capabilities.
+ */
+kernel_cap_t cap_set_effective(const kernel_cap_t pE_new)
+{
+ kernel_cap_t pE_old;
+
+ spin_lock(&task_capability_lock);
+
+ pE_old = current->cap_effective;
+ current->cap_effective = pE_new;
+
+ spin_unlock(&task_capability_lock);
+
+ return pE_old;
+}
+
+EXPORT_SYMBOL(cap_set_effective);
+
/**
* sys_capget - get the capabilities of a given process.
* @header: pointer to struct that contains capability version and
@@ -71,27 +155,13 @@ asmlinkage long sys_capget(cap_user_header_t header, cap_user_data_t dataptr)
{
int ret = 0;
pid_t pid;
- __u32 version;
struct task_struct *target;
unsigned tocopy;
kernel_cap_t pE, pI, pP;
- if (get_user(version, &header->version))
- return -EFAULT;
-
- switch (version) {
- case _LINUX_CAPABILITY_VERSION_1:
- warn_legacy_capability_use();
- tocopy = _LINUX_CAPABILITY_U32S_1;
- break;
- case _LINUX_CAPABILITY_VERSION_2:
- tocopy = _LINUX_CAPABILITY_U32S_2;
- break;
- default:
- if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
- return -EFAULT;
- return -EINVAL;
- }
+ ret = cap_validate_magic(header, &tocopy);
+ if (ret != 0)
+ return ret;
if (get_user(pid, &header->pid))
return -EFAULT;
@@ -118,7 +188,7 @@ out:
spin_unlock(&task_capability_lock);
if (!ret) {
- struct __user_cap_data_struct kdata[_LINUX_CAPABILITY_U32S];
+ struct __user_cap_data_struct kdata[_KERNEL_CAPABILITY_U32S];
unsigned i;
for (i = 0; i < tocopy; i++) {
@@ -128,7 +198,7 @@ out:
}
/*
- * Note, in the case, tocopy < _LINUX_CAPABILITY_U32S,
+ * Note, in the case, tocopy < _KERNEL_CAPABILITY_U32S,
* we silently drop the upper capabilities here. This
* has the effect of making older libcap
* implementations implicitly drop upper capability
@@ -240,30 +310,16 @@ static inline int cap_set_all(kernel_cap_t *effective,
*/
asmlinkage long sys_capset(cap_user_header_t header, const cap_user_data_t data)
{
- struct __user_cap_data_struct kdata[_LINUX_CAPABILITY_U32S];
+ struct __user_cap_data_struct kdata[_KERNEL_CAPABILITY_U32S];
unsigned i, tocopy;
kernel_cap_t inheritable, permitted, effective;
- __u32 version;
struct task_struct *target;
int ret;
pid_t pid;
- if (get_user(version, &header->version))
- return -EFAULT;
-
- switch (version) {
- case _LINUX_CAPABILITY_VERSION_1:
- warn_legacy_capability_use();
- tocopy = _LINUX_CAPABILITY_U32S_1;
- break;
- case _LINUX_CAPABILITY_VERSION_2:
- tocopy = _LINUX_CAPABILITY_U32S_2;
- break;
- default:
- if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
- return -EFAULT;
- return -EINVAL;
- }
+ ret = cap_validate_magic(header, &tocopy);
+ if (ret != 0)
+ return ret;
if (get_user(pid, &header->pid))
return -EFAULT;
@@ -281,7 +337,7 @@ asmlinkage long sys_capset(cap_user_header_t header, const cap_user_data_t data)
permitted.cap[i] = kdata[i].permitted;
inheritable.cap[i] = kdata[i].inheritable;
}
- while (i < _LINUX_CAPABILITY_U32S) {
+ while (i < _KERNEL_CAPABILITY_U32S) {
effective.cap[i] = 0;
permitted.cap[i] = 0;
inheritable.cap[i] = 0;
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