xattr_security.c

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/*
 * linux/fs/ext4/xattr_security.c
 * Handler for storing security labels as extended attributes.
 */

#include <linux/string.h>
#include <linux/fs.h>
#include <linux/security.h>
#include <linux/slab.h>
#include "ext4_jbd2.h"
#include "ext4.h"
#include "xattr.h"

static size_t
ext4_xattr_security_list(struct dentry *dentry, char *list, size_t list_size,
        const char *name, size_t name_len, int type)
{
    const size_t prefix_len = sizeof(XATTR_SECURITY_PREFIX)-1;
    const size_t total_len = prefix_len + name_len + 1;


    if (list && total_len <= list_size) {
        memcpy(list, XATTR_SECURITY_PREFIX, prefix_len);
        memcpy(list+prefix_len, name, name_len);
        list[prefix_len + name_len] = '\0';
    }
    return total_len;
}

static int
ext4_xattr_security_get(struct dentry *dentry, const char *name,
               void *buffer, size_t size, int type)
{
    if (strcmp(name, "") == 0)
        return -EINVAL;
    return ext4_xattr_get(dentry->d_inode, EXT4_XATTR_INDEX_SECURITY,
                  name, buffer, size);
}

static int
ext4_xattr_security_set(struct dentry *dentry, const char *name,
        const void *value, size_t size, int flags, int type)
{
    if (strcmp(name, "") == 0)
        return -EINVAL;
    return ext4_xattr_set(dentry->d_inode, EXT4_XATTR_INDEX_SECURITY,
                  name, value, size, flags);
}

static int
ext4_initxattrs(struct inode *inode, const struct xattr *xattr_array,
        void *fs_info)
{
    const struct xattr *xattr;
    handle_t *handle = fs_info;
    int err = 0;

    for (xattr = xattr_array; xattr->name != NULL; xattr++) {
        err = ext4_xattr_set_handle(handle, inode,
                        EXT4_XATTR_INDEX_SECURITY,
                        xattr->name, xattr->value,
                        xattr->value_len, 0);
        if (err < 0)
            break;
    }
    return err;
}

int
ext4_init_security(handle_t *handle, struct inode *inode, struct inode *dir,
           const struct qstr *qstr)
{
    return security_inode_init_security(inode, dir, qstr,
                        &ext4_initxattrs, handle);
}

const struct xattr_handler ext4_xattr_security_handler = {
    .prefix = XATTR_SECURITY_PREFIX,
    .list   = ext4_xattr_security_list,
    .get    = ext4_xattr_security_get,
    .set    = ext4_xattr_security_set,
};