capabilities: remain source compatible with 32-bit raw legacy capability support.
Source code out there hard-codes a notion of what the
_LINUX_CAPABILITY_VERSION #define means in terms of the semantics of the
raw capability system calls capget() and capset(). Its unfortunate, but
true.
Since the confusing header file has been in a released kernel, there is
software that is erroneously using 64-bit capabilities with the semantics
of 32-bit compatibilities. These recently compiled programs may suffer
corruption of their memory when sys_getcap() overwrites more memory than
they are coded to expect, and the raising of added capabilities when using
sys_capset().
As such, this patch does a number of things to clean up the situation
for all. It
1. forces the _LINUX_CAPABILITY_VERSION define to always retain its
legacy value.
2. adopts a new #define strategy for the kernel's internal
implementation of the preferred magic.
3. deprecates v2 capability magic in favor of a new (v3) magic
number. The functionality of v3 is entirely equivalent to v2,
the only difference being that the v2 magic causes the kernel
to log a "deprecated" warning so the admin can find applications
that may be using v2 inappropriately.
[User space code continues to be encouraged to use the libcap API which
protects the application from details like this. libcap-2.10 is the first
to support v3 capabilities.]
Fixes issue reported in https://bugzilla.redhat.com/show_bug.cgi?id=447518.
Thanks to Bojan Smojver for the report.
[akpm@linux-foundation.org: s/depreciate/deprecate/g]
[akpm@linux-foundation.org: be robust about put_user size]
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Andrew G. Morgan <morgan@kernel.org>
Cc: Serge E. Hallyn <serue@us.ibm.com>
Cc: Bojan Smojver <bojan@rexursive.com>
Cc: stable@kernel.org
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
diff --git a/include/linux/capability.h b/include/linux/capability.h
index f4ea0dd9a..fa830f8 100644
--- a/include/linux/capability.h
+++ b/include/linux/capability.h
@@ -31,11 +31,11 @@
#define _LINUX_CAPABILITY_VERSION_1 0x19980330
#define _LINUX_CAPABILITY_U32S_1 1
-#define _LINUX_CAPABILITY_VERSION_2 0x20071026
+#define _LINUX_CAPABILITY_VERSION_2 0x20071026 /* deprecated - 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 @@
} 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 @@
*/
#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) \
@@ -361,7 +374,7 @@
# 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 */
@@ -372,7 +385,7 @@
# 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