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[RFC] [PATCH 2/2] capabilities: implement 64-bit capabilities
From: Serge E. Hallyn <serue_at_nospam>Date: Tue Oct 16 2007 - 02:31:00 GMT
To: linux-security-module@vger.kernel.org
>From 7dd503c612afcb86b3165602ab264e2e9493b4bf Mon Sep 17 00:00:00 2001
From: Serge E. Hallyn <serue@us.ibm.com>
Date: Mon, 15 Oct 2007 20:57:52 -0400
Subject: [RFC] [PATCH 2/2] capabilities: implement 64-bit capabilities
We are out of capabilities in the 32-bit capability fields, and several users could make use of additional capabilities. Convert the capabilities to 64-bits, change the capability version number accordingly, and convert the file capability code to handle both 32-bit and 64-bit file capability xattrs.
It might seem desirable to also implement back-compatibility to read 32-bit caps from userspace, but that becomes problematic with capget, as capget could return valid info for processes not using high bits, but would have to return -EINVAL for those which were.
So with this patch, libcap would need to be updated to make use of capset/capget.
Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
---
fs/proc/array.c | 6 +++---
include/linux/capability.h | 29 ++++++++++++++++++++---------
security/commoncap.c | 37 +++++++++++++++++++++++++++++--------
3 files changed, 52 insertions(+), 20 deletions(-)
diff --git a/fs/proc/array.c b/fs/proc/array.c
index 3f4d824..c8ea46d 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -288,9 +288,9 @@ static inline char *task_sig(struct task_struct *p, char *buffer)
static inline char *task_cap(struct task_struct *p, char *buffer)
{
- return buffer + sprintf(buffer, "CapInh:\t%016x\n"
- "CapPrm:\t%016x\n"
- "CapEff:\t%016x\n",
+ return buffer + sprintf(buffer, "CapInh:\t%016lx\n"
+ "CapPrm:\t%016lx\n"
+ "CapEff:\t%016lx\n",
cap_t(p->cap_inheritable),
cap_t(p->cap_permitted),
cap_t(p->cap_effective));
diff --git a/include/linux/capability.h b/include/linux/capability.h
index bb017ed..a3da4b9 100644
--- a/include/linux/capability.h
+++ b/include/linux/capability.h
@@ -29,7 +29,7 @@ struct task_struct;
library since the draft standard requires the use of malloc/free
etc.. */
-#define _LINUX_CAPABILITY_VERSION 0x19980330
+#define _LINUX_CAPABILITY_VERSION 0x20071015
typedef struct __user_cap_header_struct {
__u32 version;
@@ -37,29 +37,40 @@ typedef struct __user_cap_header_struct {
} __user *cap_user_header_t;
typedef struct __user_cap_data_struct {
- __u32 effective;
- __u32 permitted;
- __u32 inheritable;
+ __u64 effective;
+ __u64 permitted;
+ __u64 inheritable;
} __user *cap_user_data_t;
#define XATTR_CAPS_SUFFIX "capability"
#define XATTR_NAME_CAPS XATTR_SECURITY_PREFIX XATTR_CAPS_SUFFIX
-#define XATTR_CAPS_SZ (3*sizeof(__le32))
+#define XATTR_CAPS_SZ_1 (3*sizeof(__le32))
+#define XATTR_CAPS_SZ_2 (2*sizeof(__le64) + sizeof(__le32))
#define VFS_CAP_REVISION_MASK 0xFF000000
#define VFS_CAP_REVISION_1 0x01000000
+#define VFS_CAP_REVISION_2 0x02000000
-#define VFS_CAP_REVISION VFS_CAP_REVISION_1
+#define VFS_CAP_REVISION VFS_CAP_REVISION_2
+#define XATTR_CAPS_SZ XATTR_CAPS_SZ_2
#define VFS_CAP_FLAGS_MASK ~VFS_CAP_REVISION_MASK
#define VFS_CAP_FLAGS_EFFECTIVE 0x000001
-struct vfs_cap_data {
+struct vfs_cap_data_v1 {
__u32 magic_etc; /* Little endian */
__u32 permitted; /* Little endian */
__u32 inheritable; /* Little endian */
};
+struct vfs_cap_data_v2 {
+ __u32 magic_etc; /* Little endian */
+ __u64 permitted; /* Little endian */
+ __u64 inheritable; /* Little endian */
+};
+
+typedef struct vfs_cap_data_v2 vfs_cap_data;
+
#ifdef __KERNEL__
/* #define STRICT_CAP_T_TYPECHECKS */
@@ -67,12 +78,12 @@ struct vfs_cap_data {
#ifdef STRICT_CAP_T_TYPECHECKS
typedef struct kernel_cap_struct {
- __u32 cap;
+ __u64 cap;
} kernel_cap_t;
#else
-typedef __u32 kernel_cap_t;
+typedef __u64 kernel_cap_t;
#endif
diff --git a/security/commoncap.c b/security/commoncap.c
index 542bbe9..2cca843 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -190,25 +190,46 @@ int cap_inode_killpriv(struct dentry *dentry)
return inode->i_op->removexattr(dentry, XATTR_NAME_CAPS);
}
-static inline int cap_from_disk(struct vfs_cap_data *caps,
+union vfs_cap_union {
+ struct vfs_cap_data_v1 v1;
+ struct vfs_cap_data_v2 v2;
+};
+
+static inline int cap_from_disk(union vfs_cap_union *caps,
struct linux_binprm *bprm,
int size)
{
__u32 magic_etc;
- if (size != XATTR_CAPS_SZ)
+ if (size != XATTR_CAPS_SZ_1 && size != XATTR_CAPS_SZ_2)
return -EINVAL;
- magic_etc = le32_to_cpu(caps->magic_etc);
+ magic_etc = le32_to_cpu(caps->v1.magic_etc);
switch ((magic_etc & VFS_CAP_REVISION_MASK)) {
- case VFS_CAP_REVISION:
+ case VFS_CAP_REVISION_1:
+ if (size != XATTR_CAPS_SZ_1)
+ return -EINVAL;
+ if (magic_etc & VFS_CAP_FLAGS_EFFECTIVE)
+ bprm->cap_effective = true;
+ else
+ bprm->cap_effective = false;
+ bprm->cap_permitted = to_cap_t(
+ (__u64) le32_to_cpu(caps->v1.permitted) );
+ bprm->cap_inheritable = to_cap_t(
+ (__u64) le32_to_cpu(caps->v1.inheritable) );
+ return 0;
+ case VFS_CAP_REVISION_2:
+ if (size != XATTR_CAPS_SZ_2)
+ return -EINVAL;
if (magic_etc & VFS_CAP_FLAGS_EFFECTIVE)
bprm->cap_effective = true;
else
bprm->cap_effective = false;
- bprm->cap_permitted = to_cap_t( le32_to_cpu(caps->permitted) );
- bprm->cap_inheritable = to_cap_t( le32_to_cpu(caps->inheritable) );
+ bprm->cap_permitted = to_cap_t(
+ le64_to_cpu(caps->v2.permitted) );
+ bprm->cap_inheritable = to_cap_t(
+ le64_to_cpu(caps->v2.inheritable) );
return 0;
default:
return -EINVAL;
@@ -220,7 +241,7 @@ static int get_file_caps(struct linux_binprm *bprm)
{
struct dentry *dentry;
int rc = 0;
- struct vfs_cap_data incaps;
+ union vfs_cap_union incaps;
struct inode *inode;
if (bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID) {
@@ -235,7 +256,7 @@ static int get_file_caps(struct linux_binprm *bprm)
rc = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS, NULL, 0);
if (rc > 0) {
- if (rc == XATTR_CAPS_SZ)
+ if (rc == XATTR_CAPS_SZ_2 || rc == XATTR_CAPS_SZ_1)
rc = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS,
&incaps, XATTR_CAPS_SZ);
else
--
1.5.1.1.GIT
-
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