1 files changed, 551 insertions, 0 deletions

diff --git a/fs/ext4/acl.c b/fs/ext4/acl.c
new file mode 100644
index 000000000000..9e882546d91a
--- /dev/null
+++ b/fs/ext4/acl.c
@@ -0,0 +1,551 @@
+/*
+ * 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 <linux/ext4_jbd2.h>
+#include <linux/ext4_fs.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_KERNEL);
+        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_KERNEL);
+        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_KERNEL);
+                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, struct nameidata *nd)
+{
+        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_KERNEL);
+                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 ((current->fsuid != inode->i_uid) && !capable(CAP_FOWNER))
+                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,
+};