We're moving on to v3 capabilities, to overcome a header file snafu.

v3 capabilities are functionally equivalent to v2 capabilities, but
having a different magic value allow the kernel to warn about possibly
unsafe use of v2 capabilities.

Signed-off-by: Andrew G. Morgan <morgan@kernel.org>

5 files changed, 57 insertions, 16 deletions

diff --git a/libcap/cap_alloc.c b/libcap/cap_alloc.c
index c44c7b8..5fa5e93 100644
--- a/libcap/cap_alloc.c
+++ b/libcap/cap_alloc.c
@@ -40,6 +40,10 @@ cap_t cap_init(void)
     case _LINUX_CAPABILITY_VERSION_2:
 	break;
 #endif
+#ifdef _LINUX_CAPABILITY_VERSION_3
+    case _LINUX_CAPABILITY_VERSION_3:
+	break;
+#endif
     default:                          /* No idea what to do */
 	cap_free(result);
 	result = NULL;
diff --git a/libcap/cap_file.c b/libcap/cap_file.c
index c025bf5..914ace1 100644
--- a/libcap/cap_file.c
+++ b/libcap/cap_file.c
@@ -112,6 +112,14 @@ static int _fcaps_save(struct vfs_cap_data *rawvfscap, cap_t cap_d,
 	break;
 #endif
 
+#ifdef _LINUX_CAPABILITY_VERSION_3
+    case _LINUX_CAPABILITY_VERSION_3:
+	magic = VFS_CAP_REVISION_2;
+	tocopy = VFS_CAP_U32_2;
+	*bytes_p = XATTR_CAPS_SZ_2;
+	break;
+#endif
+
     default:
 	errno = EINVAL;
 	return -1;
diff --git a/libcap/cap_text.c b/libcap/cap_text.c
index e736aee..1eaa7ae 100644
--- a/libcap/cap_text.c
+++ b/libcap/cap_text.c
@@ -158,6 +158,9 @@ cap_t cap_from_text(const char *str)
     case _LINUX_CAPABILITY_VERSION_2:
 	cap_blks = _LINUX_CAPABILITY_U32S_2;
 	break;
+    case _LINUX_CAPABILITY_VERSION_3:
+	cap_blks = _LINUX_CAPABILITY_U32S_3;
+	break;
     default:
 	errno = EINVAL;
 	return NULL;
@@ -387,6 +390,9 @@ char *cap_to_text(cap_t caps, ssize_t *length_p)
     case _LINUX_CAPABILITY_VERSION_2:
 	cap_blks = _LINUX_CAPABILITY_U32S_2;
 	break;
+    case _LINUX_CAPABILITY_VERSION_3:
+	cap_blks = _LINUX_CAPABILITY_U32S_3;
+	break;
     default:
 	errno = EINVAL;
 	return NULL;
diff --git a/libcap/include/linux/capability.h b/libcap/include/linux/capability.h
index eaab759..272e040 100644
--- a/libcap/include/linux/capability.h
+++ b/libcap/include/linux/capability.h
@@ -31,11 +31,11 @@ struct task_struct;
 #define _LINUX_CAPABILITY_VERSION_1  0x19980330
 #define _LINUX_CAPABILITY_U32S_1     1
 
-#define _LINUX_CAPABILITY_VERSION_2  0x20071026
+#define _LINUX_CAPABILITY_VERSION_2  0x20071026  /* depreciated - use v3 */
 #define _LINUX_CAPABILITY_U32S_2     2
 
-#define _LINUX_CAPABILITY_VERSION    _LINUX_CAPABILITY_VERSION_2
-#define _LINUX_CAPABILITY_U32S       _LINUX_CAPABILITY_U32S_2
+#define _LINUX_CAPABILITY_VERSION_3  0x20080522
+#define _LINUX_CAPABILITY_U32S_3     2
 
 typedef struct __user_cap_header_struct {
 	__u32 version;
@@ -77,10 +77,23 @@ struct vfs_cap_data {
 	} data[VFS_CAP_U32];
 };
 
-#ifdef __KERNEL__
+#ifndef __KERNEL__
+
+/*
+ * Backwardly compatible definition for source code - trapped in a
+ * 32-bit world. If you find you need this, please consider using
+ * libcap to untrap yourself...
+ */
+#define _LINUX_CAPABILITY_VERSION  _LINUX_CAPABILITY_VERSION_1
+#define _LINUX_CAPABILITY_U32S     _LINUX_CAPABILITY_U32S_1
+
+#else
+
+#define _KERNEL_CAPABILITY_VERSION _LINUX_CAPABILITY_VERSION_3
+#define _KERNEL_CAPABILITY_U32S    _LINUX_CAPABILITY_U32S_3
 
 typedef struct kernel_cap_struct {
-	__u32 cap[_LINUX_CAPABILITY_U32S];
+	__u32 cap[_KERNEL_CAPABILITY_U32S];
 } kernel_cap_t;
 
 #define _USER_CAP_HEADER_SIZE  (sizeof(struct __user_cap_header_struct))
@@ -351,7 +364,7 @@ typedef struct kernel_cap_struct {
  */
 
 #define CAP_FOR_EACH_U32(__capi)  \
-	for (__capi = 0; __capi < _LINUX_CAPABILITY_U32S; ++__capi)
+	for (__capi = 0; __capi < _KERNEL_CAPABILITY_U32S; ++__capi)
 
 # define CAP_FS_MASK_B0     (CAP_TO_MASK(CAP_CHOWN)		\
 			    | CAP_TO_MASK(CAP_DAC_OVERRIDE)	\
@@ -361,18 +374,18 @@ typedef struct kernel_cap_struct {
 
 # define CAP_FS_MASK_B1     (CAP_TO_MASK(CAP_MAC_OVERRIDE))
 
-#if _LINUX_CAPABILITY_U32S != 2
+#if _KERNEL_CAPABILITY_U32S != 2
 # error Fix up hand-coded capability macro initializers
 #else /* HAND-CODED capability initializers */
 
-# define CAP_EMPTY_SET    {{ 0, 0 }}
-# define CAP_FULL_SET     {{ ~0, ~0 }}
-# define CAP_INIT_EFF_SET {{ ~CAP_TO_MASK(CAP_SETPCAP), ~0 }}
-# define CAP_FS_SET       {{ CAP_FS_MASK_B0, CAP_FS_MASK_B1 } }
-# define CAP_NFSD_SET     {{ CAP_FS_MASK_B0|CAP_TO_MASK(CAP_SYS_RESOURCE), \
-			     CAP_FS_MASK_B1 } }
+# define CAP_EMPTY_SET    ((kernel_cap_t){{ 0, 0 }})
+# define CAP_FULL_SET     ((kernel_cap_t){{ ~0, ~0 }})
+# define CAP_INIT_EFF_SET ((kernel_cap_t){{ ~CAP_TO_MASK(CAP_SETPCAP), ~0 }})
+# define CAP_FS_SET       ((kernel_cap_t){{ CAP_FS_MASK_B0, CAP_FS_MASK_B1 } })
+# define CAP_NFSD_SET     ((kernel_cap_t){{ CAP_FS_MASK_B0|CAP_TO_MASK(CAP_SYS_RESOURCE), \
+					CAP_FS_MASK_B1 } })
 
-#endif /* _LINUX_CAPABILITY_U32S != 2 */
+#endif /* _KERNEL_CAPABILITY_U32S != 2 */
 
 #define CAP_INIT_INH_SET    CAP_EMPTY_SET
 
diff --git a/libcap/libcap.h b/libcap/libcap.h
index c763b84..4f64bd9 100644
--- a/libcap/libcap.h
+++ b/libcap/libcap.h
@@ -50,6 +50,16 @@
 # _LIBCAP_CAPABILITY_VERSION  _LINUX_CAPABILITY_VERSION_1
 # _LIBCAP_CAPABILITY_U32S     _LINUX_CAPABILITY_U32S_1
 
+#elif defined(_LINUX_CAPABILITY_VERSION_3)
+
+# if (_LINUX_CAPABILITY_VERSION_3 != 0x20080522)
+#  error Kernel <linux/capability.h> v3 does not match library
+#  error file "libcap.h" --> fix and recompile libcap
+# else
+#  define _LIBCAP_CAPABILITY_VERSION  _LINUX_CAPABILITY_VERSION_3
+#  define _LIBCAP_CAPABILITY_U32S     _LINUX_CAPABILITY_U32S_3
+# endif
+
 #elif (_LINUX_CAPABILITY_VERSION_2 != 0x20071026)
 
 # error Kernel <linux/capability.h> does not match library
@@ -57,8 +67,8 @@
 
 #else
 
-#define _LIBCAP_CAPABILITY_VERSION  _LINUX_CAPABILITY_VERSION_2
-#define _LIBCAP_CAPABILITY_U32S     _LINUX_CAPABILITY_U32S_2
+# define _LIBCAP_CAPABILITY_VERSION  _LINUX_CAPABILITY_VERSION_2
+# define _LIBCAP_CAPABILITY_U32S     _LINUX_CAPABILITY_U32S_2
 
 #endif