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SubjectRe: [TOMOYO #8 (2.6.25-mm1) 1/7] Introduce new LSM hooks.
* Toshiharu Harada (haradats@nttdata.co.jp) wrote:
> This patch allows LSM to check permission using "struct vfsmount"
> without passing "struct vfsmount" to VFS helper functions.

This is simply duplicating many of the existing checks.
I don't see how this is an improvement.

> --- mm.orig/fs/namei.c
> +++ mm/fs/namei.c
> @@ -1595,6 +1595,9 @@ int vfs_create(struct inode *dir, struct
> error = security_inode_create(dir, dentry, mode);
> if (error)
> return error;
> + error = security_path_create(dir, dentry, mode, nd);
> + if (error)
> + return error;

Pure duplication (of course adding nameidata, although I think you just
want path).

> DQUOT_INIT(dir);
> error = dir->i_op->create(dir, dentry, mode, nd);
> if (!error)
> @@ -1650,6 +1653,17 @@ int may_open(struct nameidata *nd, int a
...
error = vfs_permission(nd, acc_mode);
if (error)
return error;
...
> return -EPERM;
> /*
> + * security_inode_permission() called from vfs_permission()
> + * can't know that the file is going to be truncated when
> + * open(filename, O_WRONLY | O_TRUNC | O_APPEND) is used.
> + * So, this hook checks O_APPEND and O_TRUNC flags as well
> + * as MAY_READ and MAY_WRITE flags.
> + */
> + error = security_path_open(nd->path.dentry, nd->path.mnt, flag);
> + if (error)
> + return error;

Also duplication. And why the unique flag handling, you don't seem to
ever check?

> +
> + /*
> * Ensure there are no outstanding leases on the file.
> */
> error = break_lease(inode, flag);
> @@ -2021,7 +2035,12 @@ fail:
> }
> EXPORT_SYMBOL_GPL(lookup_create);
>
> -int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
> +/*
> + * These pre_vfs_*() functions are separated from vfs_*() functions so that
> + * LSM's security_path_*() functions can do DAC checks before MAC checks
> + * without duplicating may_create()/may_delete() functions.
> + */
> +int pre_vfs_mknod(struct inode *dir, struct dentry *dentry, int mode)
> {
> int error = may_create(dir, dentry, NULL);
>
> @@ -2033,6 +2052,14 @@ int vfs_mknod(struct inode *dir, struct
>
> if (!dir->i_op || !dir->i_op->mknod)
> return -EPERM;
> + return 0;
> +}
> +
> +int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
> +{
> + int error = pre_vfs_mknod(dir, dentry, mode);
> + if (error)
> + return error;

More duplication, you'll get a call chain like:

sys_mknod
security_path_mknod
pre_vfs_mknod
vfs_mknod
pre_vfs_mknod
security_inode_mknod




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