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This patch add a generic cpu endian caps structure and externally available

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functions which retrieve fcaps information from disk.  This information is
necessary so fcaps information can be collected and recorded by the audit
system.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
This commit is contained in:
Eric Paris 2008-11-11 21:48:10 +11:00 committed by James Morris
parent 9d36be76c5
commit c0b004413a
2 changed files with 78 additions and 58 deletions
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7
include/linux/capability.h
View file

@ -99,6 +99,13 @@ typedef struct kernel_cap_struct {
__u32 cap[_KERNEL_CAPABILITY_U32S];
} kernel_cap_t;
/* exact same as vfs_cap_data but in cpu endian and always filled completely */
struct cpu_vfs_cap_data {
__u32 magic_etc;
kernel_cap_t permitted;
kernel_cap_t inheritable;
};
#define _USER_CAP_HEADER_SIZE (sizeof(struct __user_cap_header_struct))
#define _KERNEL_CAP_T_SIZE (sizeof(kernel_cap_t))

127
security/commoncap.c
View file

@ -202,17 +202,70 @@ 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,
struct linux_binprm *bprm, unsigned size)
static inline int bprm_caps_from_vfs_caps(struct cpu_vfs_cap_data *caps,
struct linux_binprm *bprm)
{
unsigned i;
int ret = 0;
if (caps->magic_etc & VFS_CAP_FLAGS_EFFECTIVE)
bprm->cap_effective = true;
else
bprm->cap_effective = false;
CAP_FOR_EACH_U32(i) {
__u32 permitted = caps->permitted.cap[i];
__u32 inheritable = caps->inheritable.cap[i];
/*
* pP' = (X & fP) | (pI & fI)
*/
bprm->cap_post_exec_permitted.cap[i] =
(current->cap_bset.cap[i] & permitted) |
(current->cap_inheritable.cap[i] & inheritable);
if (permitted & ~bprm->cap_post_exec_permitted.cap[i]) {
/*
* insufficient to execute correctly
*/
ret = -EPERM;
}
}
/*
* For legacy apps, with no internal support for recognizing they
* do not have enough capabilities, we return an error if they are
* missing some "forced" (aka file-permitted) capabilities.
*/
return bprm->cap_effective ? ret : 0;
}
int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data *cpu_caps)
{
struct inode *inode = dentry->d_inode;
__u32 magic_etc;
unsigned tocopy, i;
int ret;
int size;
struct vfs_cap_data caps;
memset(cpu_caps, 0, sizeof(struct cpu_vfs_cap_data));
if (!inode || !inode->i_op || !inode->i_op->getxattr)
return -ENODATA;
size = inode->i_op->getxattr((struct dentry *)dentry, XATTR_NAME_CAPS, &caps,
XATTR_CAPS_SZ);
if (size == -ENODATA || size == -EOPNOTSUPP) {
/* no data, that's ok */
return -ENODATA;
}
if (size < 0)
return size;
if (size < sizeof(magic_etc))
return -EINVAL;
magic_etc = le32_to_cpu(caps->magic_etc);
cpu_caps->magic_etc = magic_etc = le32_to_cpu(caps.magic_etc);
switch ((magic_etc & VFS_CAP_REVISION_MASK)) {
case VFS_CAP_REVISION_1:
@ -229,46 +282,13 @@ static inline int cap_from_disk(struct vfs_cap_data *caps,
return -EINVAL;
}
if (magic_etc & VFS_CAP_FLAGS_EFFECTIVE) {
bprm->cap_effective = true;
} else {
bprm->cap_effective = false;
}
ret = 0;
CAP_FOR_EACH_U32(i) {
__u32 value_cpu;
if (i >= tocopy) {
/*
* Legacy capability sets have no upper bits
*/
bprm->cap_post_exec_permitted.cap[i] = 0;
continue;
if (i >= tocopy)
break;
cpu_caps->permitted.cap[i] = le32_to_cpu(caps.data[i].permitted);
cpu_caps->inheritable.cap[i] = le32_to_cpu(caps.data[i].inheritable);
}
/*
* pP' = (X & fP) | (pI & fI)
*/
value_cpu = le32_to_cpu(caps->data[i].permitted);
bprm->cap_post_exec_permitted.cap[i] =
(current->cap_bset.cap[i] & value_cpu) |
(current->cap_inheritable.cap[i] &
le32_to_cpu(caps->data[i].inheritable));
if (value_cpu & ~bprm->cap_post_exec_permitted.cap[i]) {
/*
* insufficient to execute correctly
*/
ret = -EPERM;
}
}
/*
* For legacy apps, with no internal support for recognizing they
* do not have enough capabilities, we return an error if they are
* missing some "forced" (aka file-permitted) capabilities.
*/
return bprm->cap_effective ? ret : 0;
return 0;
}
/* Locate any VFS capabilities: */
@ -276,8 +296,7 @@ static int get_file_caps(struct linux_binprm *bprm)
{
struct dentry *dentry;
int rc = 0;
struct vfs_cap_data vcaps;
struct inode *inode;
struct cpu_vfs_cap_data vcaps;
bprm_clear_caps(bprm);
@ -288,24 +307,18 @@ static int get_file_caps(struct linux_binprm *bprm)
return 0;
dentry = dget(bprm->file->f_dentry);
inode = dentry->d_inode;
if (!inode->i_op || !inode->i_op->getxattr)
goto out;
rc = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS, &vcaps,
XATTR_CAPS_SZ);
if (rc == -ENODATA || rc == -EOPNOTSUPP) {
/* no data, that's ok */
rc = get_vfs_caps_from_disk(dentry, &vcaps);
if (rc < 0) {
if (rc == -EINVAL)
printk(KERN_NOTICE "%s: get_vfs_caps_from_disk returned %d for %s\n",
__func__, rc, bprm->filename);
else if (rc == -ENODATA)
rc = 0;
goto out;
}
if (rc < 0)
goto out;
rc = cap_from_disk(&vcaps, bprm, rc);
if (rc == -EINVAL)
printk(KERN_NOTICE "%s: cap_from_disk returned %d for %s\n",
__func__, rc, bprm->filename);
rc = bprm_caps_from_vfs_caps(&vcaps, bprm);
out:
dput(dentry);