Merge git://git.kernel.org/pub/scm/linux/kernel/git/steve/gfs2-2.6-fixes

[pandora-kernel.git] / kernel / capability.c

diff --git a/kernel/capability.c b/kernel/capability.c
index 39e8193..cfbe442 100644 (file)
--- a/kernel/capability.c
+++ b/kernel/capability.c
@@ -52,6 +52,69 @@ 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
@@ -71,27 +134,13 @@ 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 +167,7 @@ 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 +177,7 @@ 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 +289,16 @@ 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 +316,7 @@ 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;