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root/fs/ext4/acl.c

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DEFINITIONS

This source file includes following definitions.
  1. ext4_acl_from_disk
  2. ext4_acl_to_disk
  3. ext4_iget_acl
  4. ext4_iset_acl
  5. ext4_get_acl
  6. ext4_set_acl
  7. ext4_check_acl
  8. ext4_permission
  9. ext4_init_acl
  10. ext4_acl_chmod
  11. ext4_xattr_list_acl_access
  12. ext4_xattr_list_acl_default
  13. ext4_xattr_get_acl
  14. ext4_xattr_get_acl_access
  15. ext4_xattr_get_acl_default
  16. ext4_xattr_set_acl
  17. ext4_xattr_set_acl_access
  18. ext4_xattr_set_acl_default

/*
 * linux/fs/ext4/acl.c
 *
 * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
 */

#include <linux/init.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/capability.h>
#include <linux/fs.h>
#include "ext4_jbd2.h"
#include "ext4.h"
#include "xattr.h"
#include "acl.h"

/*
 * Convert from filesystem to in-memory representation.
 */
static struct posix_acl *
ext4_acl_from_disk(const void *value, size_t size)
{
        const char *end = (char *)value + size;
        int n, count;
        struct posix_acl *acl;

        if (!value)
                return NULL;
        if (size < sizeof(ext4_acl_header))
                 return ERR_PTR(-EINVAL);
        if (((ext4_acl_header *)value)->a_version !=
            cpu_to_le32(EXT4_ACL_VERSION))
                return ERR_PTR(-EINVAL);
        value = (char *)value + sizeof(ext4_acl_header);
        count = ext4_acl_count(size);
        if (count < 0)
                return ERR_PTR(-EINVAL);
        if (count == 0)
                return NULL;
        acl = posix_acl_alloc(count, GFP_NOFS);
        if (!acl)
                return ERR_PTR(-ENOMEM);
        for (n = 0; n < count; n++) {
                ext4_acl_entry *entry =
                        (ext4_acl_entry *)value;
                if ((char *)value + sizeof(ext4_acl_entry_short) > end)
                        goto fail;
                acl->a_entries[n].e_tag  = le16_to_cpu(entry->e_tag);
                acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);

                switch (acl->a_entries[n].e_tag) {
                case ACL_USER_OBJ:
                case ACL_GROUP_OBJ:
                case ACL_MASK:
                case ACL_OTHER:
                        value = (char *)value +
                                sizeof(ext4_acl_entry_short);
                        acl->a_entries[n].e_id = ACL_UNDEFINED_ID;
                        break;

                case ACL_USER:
                case ACL_GROUP:
                        value = (char *)value + sizeof(ext4_acl_entry);
                        if ((char *)value > end)
                                goto fail;
                        acl->a_entries[n].e_id =
                                le32_to_cpu(entry->e_id);
                        break;

                default:
                        goto fail;
                }
        }
        if (value != end)
                goto fail;
        return acl;

fail:
        posix_acl_release(acl);
        return ERR_PTR(-EINVAL);
}

/*
 * Convert from in-memory to filesystem representation.
 */
static void *
ext4_acl_to_disk(const struct posix_acl *acl, size_t *size)
{
        ext4_acl_header *ext_acl;
        char *e;
        size_t n;

        *size = ext4_acl_size(acl->a_count);
        ext_acl = kmalloc(sizeof(ext4_acl_header) + acl->a_count *
                        sizeof(ext4_acl_entry), GFP_NOFS);
        if (!ext_acl)
                return ERR_PTR(-ENOMEM);
        ext_acl->a_version = cpu_to_le32(EXT4_ACL_VERSION);
        e = (char *)ext_acl + sizeof(ext4_acl_header);
        for (n = 0; n < acl->a_count; n++) {
                ext4_acl_entry *entry = (ext4_acl_entry *)e;
                entry->e_tag  = cpu_to_le16(acl->a_entries[n].e_tag);
                entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
                switch (acl->a_entries[n].e_tag) {
                case ACL_USER:
                case ACL_GROUP:
                        entry->e_id = cpu_to_le32(acl->a_entries[n].e_id);
                        e += sizeof(ext4_acl_entry);
                        break;

                case ACL_USER_OBJ:
                case ACL_GROUP_OBJ:
                case ACL_MASK:
                case ACL_OTHER:
                        e += sizeof(ext4_acl_entry_short);
                        break;

                default:
                        goto fail;
                }
        }
        return (char *)ext_acl;

fail:
        kfree(ext_acl);
        return ERR_PTR(-EINVAL);
}

static inline struct posix_acl *
ext4_iget_acl(struct inode *inode, struct posix_acl **i_acl)
{
        struct posix_acl *acl = EXT4_ACL_NOT_CACHED;

        spin_lock(&inode->i_lock);
        if (*i_acl != EXT4_ACL_NOT_CACHED)
                acl = posix_acl_dup(*i_acl);
        spin_unlock(&inode->i_lock);

        return acl;
}

static inline void
ext4_iset_acl(struct inode *inode, struct posix_acl **i_acl,
                struct posix_acl *acl)
{
        spin_lock(&inode->i_lock);
        if (*i_acl != EXT4_ACL_NOT_CACHED)
                posix_acl_release(*i_acl);
        *i_acl = posix_acl_dup(acl);
        spin_unlock(&inode->i_lock);
}

/*
 * Inode operation get_posix_acl().
 *
 * inode->i_mutex: don't care
 */
static struct posix_acl *
ext4_get_acl(struct inode *inode, int type)
{
        struct ext4_inode_info *ei = EXT4_I(inode);
        int name_index;
        char *value = NULL;
        struct posix_acl *acl;
        int retval;

        if (!test_opt(inode->i_sb, POSIX_ACL))
                return NULL;

        switch (type) {
        case ACL_TYPE_ACCESS:
                acl = ext4_iget_acl(inode, &ei->i_acl);
                if (acl != EXT4_ACL_NOT_CACHED)
                        return acl;
                name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
                break;

        case ACL_TYPE_DEFAULT:
                acl = ext4_iget_acl(inode, &ei->i_default_acl);
                if (acl != EXT4_ACL_NOT_CACHED)
                        return acl;
                name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
                break;

        default:
                return ERR_PTR(-EINVAL);
        }
        retval = ext4_xattr_get(inode, name_index, "", NULL, 0);
        if (retval > 0) {
                value = kmalloc(retval, GFP_NOFS);
                if (!value)
                        return ERR_PTR(-ENOMEM);
                retval = ext4_xattr_get(inode, name_index, "", value, retval);
        }
        if (retval > 0)
                acl = ext4_acl_from_disk(value, retval);
        else if (retval == -ENODATA || retval == -ENOSYS)
                acl = NULL;
        else
                acl = ERR_PTR(retval);
        kfree(value);

        if (!IS_ERR(acl)) {
                switch (type) {
                case ACL_TYPE_ACCESS:
                        ext4_iset_acl(inode, &ei->i_acl, acl);
                        break;

                case ACL_TYPE_DEFAULT:
                        ext4_iset_acl(inode, &ei->i_default_acl, acl);
                        break;
                }
        }
        return acl;
}

/*
 * Set the access or default ACL of an inode.
 *
 * inode->i_mutex: down unless called from ext4_new_inode
 */
static int
ext4_set_acl(handle_t *handle, struct inode *inode, int type,
             struct posix_acl *acl)
{
        struct ext4_inode_info *ei = EXT4_I(inode);
        int name_index;
        void *value = NULL;
        size_t size = 0;
        int error;

        if (S_ISLNK(inode->i_mode))
                return -EOPNOTSUPP;

        switch (type) {
        case ACL_TYPE_ACCESS:
                name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
                if (acl) {
                        mode_t mode = inode->i_mode;
                        error = posix_acl_equiv_mode(acl, &mode);
                        if (error < 0)
                                return error;
                        else {
                                inode->i_mode = mode;
                                ext4_mark_inode_dirty(handle, inode);
                                if (error == 0)
                                        acl = NULL;
                        }
                }
                break;

        case ACL_TYPE_DEFAULT:
                name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
                if (!S_ISDIR(inode->i_mode))
                        return acl ? -EACCES : 0;
                break;

        default:
                return -EINVAL;
        }
        if (acl) {
                value = ext4_acl_to_disk(acl, &size);
                if (IS_ERR(value))
                        return (int)PTR_ERR(value);
        }

        error = ext4_xattr_set_handle(handle, inode, name_index, "",
                                      value, size, 0);

        kfree(value);
        if (!error) {
                switch (type) {
                case ACL_TYPE_ACCESS:
                        ext4_iset_acl(inode, &ei->i_acl, acl);
                        break;

                case ACL_TYPE_DEFAULT:
                        ext4_iset_acl(inode, &ei->i_default_acl, acl);
                        break;
                }
        }
        return error;
}

static int
ext4_check_acl(struct inode *inode, int mask)
{
        struct posix_acl *acl = ext4_get_acl(inode, ACL_TYPE_ACCESS);

        if (IS_ERR(acl))
                return PTR_ERR(acl);
        if (acl) {
                int error = posix_acl_permission(inode, acl, mask);
                posix_acl_release(acl);
                return error;
        }

        return -EAGAIN;
}

int
ext4_permission(struct inode *inode, int mask)
{
        return generic_permission(inode, mask, ext4_check_acl);
}

/*
 * Initialize the ACLs of a new inode. Called from ext4_new_inode.
 *
 * dir->i_mutex: down
 * inode->i_mutex: up (access to inode is still exclusive)
 */
int
ext4_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
{
        struct posix_acl *acl = NULL;
        int error = 0;

        if (!S_ISLNK(inode->i_mode)) {
                if (test_opt(dir->i_sb, POSIX_ACL)) {
                        acl = ext4_get_acl(dir, ACL_TYPE_DEFAULT);
                        if (IS_ERR(acl))
                                return PTR_ERR(acl);
                }
                if (!acl)
                        inode->i_mode &= ~current->fs->umask;
        }
        if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
                struct posix_acl *clone;
                mode_t mode;

                if (S_ISDIR(inode->i_mode)) {
                        error = ext4_set_acl(handle, inode,
                                             ACL_TYPE_DEFAULT, acl);
                        if (error)
                                goto cleanup;
                }
                clone = posix_acl_clone(acl, GFP_NOFS);
                error = -ENOMEM;
                if (!clone)
                        goto cleanup;

                mode = inode->i_mode;
                error = posix_acl_create_masq(clone, &mode);
                if (error >= 0) {
                        inode->i_mode = mode;
                        if (error > 0) {
                                /* This is an extended ACL */
                                error = ext4_set_acl(handle, inode,
                                                     ACL_TYPE_ACCESS, clone);
                        }
                }
                posix_acl_release(clone);
        }
cleanup:
        posix_acl_release(acl);
        return error;
}

/*
 * Does chmod for an inode that may have an Access Control List. The
 * inode->i_mode field must be updated to the desired value by the caller
 * before calling this function.
 * Returns 0 on success, or a negative error number.
 *
 * We change the ACL rather than storing some ACL entries in the file
 * mode permission bits (which would be more efficient), because that
 * would break once additional permissions (like  ACL_APPEND, ACL_DELETE
 * for directories) are added. There are no more bits available in the
 * file mode.
 *
 * inode->i_mutex: down
 */
int
ext4_acl_chmod(struct inode *inode)
{
        struct posix_acl *acl, *clone;
        int error;

        if (S_ISLNK(inode->i_mode))
                return -EOPNOTSUPP;
        if (!test_opt(inode->i_sb, POSIX_ACL))
                return 0;
        acl = ext4_get_acl(inode, ACL_TYPE_ACCESS);
        if (IS_ERR(acl) || !acl)
                return PTR_ERR(acl);
        clone = posix_acl_clone(acl, GFP_KERNEL);
        posix_acl_release(acl);
        if (!clone)
                return -ENOMEM;
        error = posix_acl_chmod_masq(clone, inode->i_mode);
        if (!error) {
                handle_t *handle;
                int retries = 0;

        retry:
                handle = ext4_journal_start(inode,
                                EXT4_DATA_TRANS_BLOCKS(inode->i_sb));
                if (IS_ERR(handle)) {
                        error = PTR_ERR(handle);
                        ext4_std_error(inode->i_sb, error);
                        goto out;
                }
                error = ext4_set_acl(handle, inode, ACL_TYPE_ACCESS, clone);
                ext4_journal_stop(handle);
                if (error == -ENOSPC &&
                    ext4_should_retry_alloc(inode->i_sb, &retries))
                        goto retry;
        }
out:
        posix_acl_release(clone);
        return error;
}

/*
 * Extended attribute handlers
 */
static size_t
ext4_xattr_list_acl_access(struct inode *inode, char *list, size_t list_len,
                           const char *name, size_t name_len)
{
        const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);

        if (!test_opt(inode->i_sb, POSIX_ACL))
                return 0;
        if (list && size <= list_len)
                memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
        return size;
}

static size_t
ext4_xattr_list_acl_default(struct inode *inode, char *list, size_t list_len,
                            const char *name, size_t name_len)
{
        const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);

        if (!test_opt(inode->i_sb, POSIX_ACL))
                return 0;
        if (list && size <= list_len)
                memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
        return size;
}

static int
ext4_xattr_get_acl(struct inode *inode, int type, void *buffer, size_t size)
{
        struct posix_acl *acl;
        int error;

        if (!test_opt(inode->i_sb, POSIX_ACL))
                return -EOPNOTSUPP;

        acl = ext4_get_acl(inode, type);
        if (IS_ERR(acl))
                return PTR_ERR(acl);
        if (acl == NULL)
                return -ENODATA;
        error = posix_acl_to_xattr(acl, buffer, size);
        posix_acl_release(acl);

        return error;
}

static int
ext4_xattr_get_acl_access(struct inode *inode, const char *name,
                          void *buffer, size_t size)
{
        if (strcmp(name, "") != 0)
                return -EINVAL;
        return ext4_xattr_get_acl(inode, ACL_TYPE_ACCESS, buffer, size);
}

static int
ext4_xattr_get_acl_default(struct inode *inode, const char *name,
                           void *buffer, size_t size)
{
        if (strcmp(name, "") != 0)
                return -EINVAL;
        return ext4_xattr_get_acl(inode, ACL_TYPE_DEFAULT, buffer, size);
}

static int
ext4_xattr_set_acl(struct inode *inode, int type, const void *value,
                   size_t size)
{
        handle_t *handle;
        struct posix_acl *acl;
        int error, retries = 0;

        if (!test_opt(inode->i_sb, POSIX_ACL))
                return -EOPNOTSUPP;
        if (!is_owner_or_cap(inode))
                return -EPERM;

        if (value) {
                acl = posix_acl_from_xattr(value, size);
                if (IS_ERR(acl))
                        return PTR_ERR(acl);
                else if (acl) {
                        error = posix_acl_valid(acl);
                        if (error)
                                goto release_and_out;
                }
        } else
                acl = NULL;

retry:
        handle = ext4_journal_start(inode, EXT4_DATA_TRANS_BLOCKS(inode->i_sb));
        if (IS_ERR(handle))
                return PTR_ERR(handle);
        error = ext4_set_acl(handle, inode, type, acl);
        ext4_journal_stop(handle);
        if (error == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
                goto retry;

release_and_out:
        posix_acl_release(acl);
        return error;
}

static int
ext4_xattr_set_acl_access(struct inode *inode, const char *name,
                          const void *value, size_t size, int flags)
{
        if (strcmp(name, "") != 0)
                return -EINVAL;
        return ext4_xattr_set_acl(inode, ACL_TYPE_ACCESS, value, size);
}

static int
ext4_xattr_set_acl_default(struct inode *inode, const char *name,
                           const void *value, size_t size, int flags)
{
        if (strcmp(name, "") != 0)
                return -EINVAL;
        return ext4_xattr_set_acl(inode, ACL_TYPE_DEFAULT, value, size);
}

struct xattr_handler ext4_xattr_acl_access_handler = {
        .prefix = POSIX_ACL_XATTR_ACCESS,
        .list   = ext4_xattr_list_acl_access,
        .get    = ext4_xattr_get_acl_access,
        .set    = ext4_xattr_set_acl_access,
};

struct xattr_handler ext4_xattr_acl_default_handler = {
        .prefix = POSIX_ACL_XATTR_DEFAULT,
        .list   = ext4_xattr_list_acl_default,
        .get    = ext4_xattr_get_acl_default,
        .set    = ext4_xattr_set_acl_default,
};

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