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SubjectRe: (repost) Confirmation of methods for calculating requested pathname.
From
Date
Hello.

Serge E. Hallyn wrote:
> I thought Al and others (Stephen?) had made it clear that the thing to do was
> add new lsm hooks there.
Thank you for a hint.
I have a question to Al Viro: Is it acceptable for you to introduce
new LSM hooks (i.e. security_path_*()) where struct vfsmount is available?
If it is acceptable, I'd like to start from the following patch.

Regards.
-----
Subject: Introduce new LSM hooks.

This patch allows LSM to check permission using "struct vfsmount"
without passing "struct vfsmount" to VFS helper functions.

Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp>
---
fs/namei.c | 37 ++++++++++++
fs/open.c | 5 +
include/linux/security.h | 135 +++++++++++++++++++++++++++++++++++++++++++++++
net/unix/af_unix.c | 4 +
security/capability.c | 53 ++++++++++++++++++
security/security.c | 63 +++++++++++++++++++++
6 files changed, 297 insertions(+)

--- linux-2.6.27-rc5.orig/fs/namei.c
+++ linux-2.6.27-rc5/fs/namei.c
@@ -1585,6 +1585,10 @@ int may_open(struct nameidata *nd, int a
* Refuse to truncate files with mandatory locks held on them.
*/
error = locks_verify_locked(inode);
+ if (!error)
+ error = security_path_truncate(&nd->path, 0,
+ ATTR_MTIME|ATTR_CTIME|ATTR_OPEN,
+ NULL);
if (!error) {
DQUOT_INIT(inode);

@@ -1615,7 +1619,11 @@ static int __open_namei_create(struct na

if (!IS_POSIXACL(dir->d_inode))
mode &= ~current->fs->umask;
+ error = security_path_mknod(&nd->path, path->dentry, mode, 0);
+ if (error)
+ goto out_unlock;
error = vfs_create(dir->d_inode, path->dentry, mode, nd);
+out_unlock:
mutex_unlock(&dir->d_inode->i_mutex);
dput(nd->path.dentry);
nd->path.dentry = path->dentry;
@@ -2018,6 +2026,9 @@ asmlinkage long sys_mknodat(int dfd, con
error = mnt_want_write(nd.path.mnt);
if (error)
goto out_dput;
+ error = security_path_mknod(&nd.path, dentry, mode, dev);
+ if (error)
+ goto out_drop_write;
switch (mode & S_IFMT) {
case 0: case S_IFREG:
error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd);
@@ -2030,6 +2041,7 @@ asmlinkage long sys_mknodat(int dfd, con
error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0);
break;
}
+out_drop_write:
mnt_drop_write(nd.path.mnt);
out_dput:
dput(dentry);
@@ -2089,7 +2101,11 @@ asmlinkage long sys_mkdirat(int dfd, con
error = mnt_want_write(nd.path.mnt);
if (error)
goto out_dput;
+ error = security_path_mkdir(&nd.path, dentry, mode);
+ if (error)
+ goto out_drop_write;
error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode);
+out_drop_write:
mnt_drop_write(nd.path.mnt);
out_dput:
dput(dentry);
@@ -2196,7 +2212,11 @@ static long do_rmdir(int dfd, const char
error = mnt_want_write(nd.path.mnt);
if (error)
goto exit3;
+ error = security_path_rmdir(&nd.path, dentry);
+ if (error)
+ goto exit4;
error = vfs_rmdir(nd.path.dentry->d_inode, dentry);
+exit4:
mnt_drop_write(nd.path.mnt);
exit3:
dput(dentry);
@@ -2278,7 +2298,11 @@ static long do_unlinkat(int dfd, const c
error = mnt_want_write(nd.path.mnt);
if (error)
goto exit2;
+ error = security_path_unlink(&nd.path, dentry);
+ if (error)
+ goto exit3;
error = vfs_unlink(nd.path.dentry->d_inode, dentry);
+exit3:
mnt_drop_write(nd.path.mnt);
exit2:
dput(dentry);
@@ -2359,7 +2383,11 @@ asmlinkage long sys_symlinkat(const char
error = mnt_want_write(nd.path.mnt);
if (error)
goto out_dput;
+ error = security_path_symlink(&nd.path, dentry, from);
+ if (error)
+ goto out_drop_write;
error = vfs_symlink(nd.path.dentry->d_inode, dentry, from);
+out_drop_write:
mnt_drop_write(nd.path.mnt);
out_dput:
dput(dentry);
@@ -2456,7 +2484,11 @@ asmlinkage long sys_linkat(int olddfd, c
error = mnt_want_write(nd.path.mnt);
if (error)
goto out_dput;
+ error = security_path_link(old_path.dentry, &nd.path, new_dentry);
+ if (error)
+ goto out_drop_write;
error = vfs_link(old_path.dentry, nd.path.dentry->d_inode, new_dentry);
+out_drop_write:
mnt_drop_write(nd.path.mnt);
out_dput:
dput(new_dentry);
@@ -2688,8 +2720,13 @@ asmlinkage long sys_renameat(int olddfd,
error = mnt_want_write(oldnd.path.mnt);
if (error)
goto exit5;
+ error = security_path_rename(&oldnd.path, old_dentry,
+ &newnd.path, new_dentry);
+ if (error)
+ goto exit6;
error = vfs_rename(old_dir->d_inode, old_dentry,
new_dir->d_inode, new_dentry);
+exit6:
mnt_drop_write(oldnd.path.mnt);
exit5:
dput(new_dentry);
--- linux-2.6.27-rc5.orig/fs/open.c
+++ linux-2.6.27-rc5/fs/open.c
@@ -272,6 +272,8 @@ static long do_sys_truncate(const char _
goto put_write_and_out;

error = locks_verify_truncate(inode, NULL, length);
+ if (!error)
+ error = security_path_truncate(&path, length, 0, NULL);
if (!error) {
DQUOT_INIT(inode);
error = do_truncate(path.dentry, length, 0, NULL);
@@ -329,6 +331,9 @@ static long do_sys_ftruncate(unsigned in

error = locks_verify_truncate(inode, file, length);
if (!error)
+ error = security_path_truncate(&file->f_path, length,
+ ATTR_MTIME|ATTR_CTIME, file);
+ if (!error)
error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, file);
out_putf:
fput(file);
--- linux-2.6.27-rc5.orig/include/linux/security.h
+++ linux-2.6.27-rc5/include/linux/security.h
@@ -345,17 +345,37 @@ static inline void security_free_mnt_opt
* @dir contains the inode structure of the parent directory of the new link.
* @new_dentry contains the dentry structure for the new link.
* Return 0 if permission is granted.
+ * @path_link:
+ * Check permission before creating a new hard link to a file.
+ * @old_dentry contains the dentry structure for an existing link
+ * to the file.
+ * @new_dir contains the path structure of the parent directory of
+ * the new link.
+ * @new_dentry contains the dentry structure for the new link.
+ * Return 0 if permission is granted.
* @inode_unlink:
* Check the permission to remove a hard link to a file.
* @dir contains the inode structure of parent directory of the file.
* @dentry contains the dentry structure for file to be unlinked.
* Return 0 if permission is granted.
+ * @path_unlink:
+ * Check the permission to remove a hard link to a file.
+ * @dir contains the path structure of parent directory of the file.
+ * @dentry contains the dentry structure for file to be unlinked.
+ * Return 0 if permission is granted.
* @inode_symlink:
* Check the permission to create a symbolic link to a file.
* @dir contains the inode structure of parent directory of the symbolic link.
* @dentry contains the dentry structure of the symbolic link.
* @old_name contains the pathname of file.
* Return 0 if permission is granted.
+ * @path_symlink:
+ * Check the permission to create a symbolic link to a file.
+ * @dir contains the path structure of parent directory of
+ * the symbolic link.
+ * @dentry contains the dentry structure of the symbolic link.
+ * @old_name contains the pathname of file.
+ * Return 0 if permission is granted.
* @inode_mkdir:
* Check permissions to create a new directory in the existing directory
* associated with inode strcture @dir.
@@ -363,11 +383,25 @@ static inline void security_free_mnt_opt
* @dentry contains the dentry structure of new directory.
* @mode contains the mode of new directory.
* Return 0 if permission is granted.
+ * @path_mkdir:
+ * Check permissions to create a new directory in the existing directory
+ * associated with path strcture @path.
+ * @dir containst the path structure of parent of the directory
+ * to be created.
+ * @dentry contains the dentry structure of new directory.
+ * @mode contains the mode of new directory.
+ * Return 0 if permission is granted.
* @inode_rmdir:
* Check the permission to remove a directory.
* @dir contains the inode structure of parent of the directory to be removed.
* @dentry contains the dentry structure of directory to be removed.
* Return 0 if permission is granted.
+ * @path_rmdir:
+ * Check the permission to remove a directory.
+ * @dir contains the path structure of parent of the directory to be
+ * removed.
+ * @dentry contains the dentry structure of directory to be removed.
+ * Return 0 if permission is granted.
* @inode_mknod:
* Check permissions when creating a special file (or a socket or a fifo
* file created via the mknod system call). Note that if mknod operation
@@ -378,6 +412,15 @@ static inline void security_free_mnt_opt
* @mode contains the mode of the new file.
* @dev contains the device number.
* Return 0 if permission is granted.
+ * @path_mknod:
+ * Check permissions when creating a file. Note that this hook is called
+ * even if mknod operation is being done for a regular file.
+ * @dir contains the path structure of parent of the new file.
+ * @dentry contains the dentry structure of the new file.
+ * @mode contains the mode of the new file.
+ * @dev contains the undecoded device number. Use new_decode_dev() to get
+ * the decoded device number.
+ * Return 0 if permission is granted.
* @inode_rename:
* Check for permission to rename a file or directory.
* @old_dir contains the inode structure for parent of the old link.
@@ -385,6 +428,13 @@ static inline void security_free_mnt_opt
* @new_dir contains the inode structure for parent of the new link.
* @new_dentry contains the dentry structure of the new link.
* Return 0 if permission is granted.
+ * @path_rename:
+ * Check for permission to rename a file or directory.
+ * @old_dir contains the path structure for parent of the old link.
+ * @old_dentry contains the dentry structure of the old link.
+ * @new_dir contains the path structure for parent of the new link.
+ * @new_dentry contains the dentry structure of the new link.
+ * Return 0 if permission is granted.
* @inode_readlink:
* Check the permission to read the symbolic link.
* @dentry contains the dentry structure for the file link.
@@ -413,6 +463,13 @@ static inline void security_free_mnt_opt
* @dentry contains the dentry structure for the file.
* @attr is the iattr structure containing the new file attributes.
* Return 0 if permission is granted.
+ * @path_truncate:
+ * Check permission before truncating a file.
+ * @path contains the path structure for the file.
+ * @length is the new length of the file.
+ * @time_attrs is the flags passed to do_truncate().
+ * @filp is the file structure (may be NULL).
+ * Return 0 if permission is granted.
* @inode_getattr:
* Check permission before obtaining file attributes.
* @mnt is the vfsmount where the dentry was looked up
@@ -1350,6 +1407,20 @@ struct security_operations {
struct super_block *newsb);
int (*sb_parse_opts_str) (char *options, struct security_mnt_opts *opts);

+ int (*path_unlink) (struct path *dir, struct dentry *dentry);
+ int (*path_mkdir) (struct path *dir, struct dentry *dentry, int mode);
+ int (*path_rmdir) (struct path *dir, struct dentry *dentry);
+ int (*path_mknod) (struct path *dir, struct dentry *dentry, int mode,
+ unsigned int dev);
+ int (*path_truncate) (struct path *path, loff_t length,
+ unsigned int time_attrs, struct file *filp);
+ int (*path_symlink) (struct path *dir, struct dentry *dentry,
+ const char *old_name);
+ int (*path_link) (struct dentry *old_dentry, struct path *new_dir,
+ struct dentry *new_dentry);
+ int (*path_rename) (struct path *old_dir, struct dentry *old_dentry,
+ struct path *new_dir, struct dentry *new_dentry);
+
int (*inode_alloc_security) (struct inode *inode);
void (*inode_free_security) (struct inode *inode);
int (*inode_init_security) (struct inode *inode, struct inode *dir,
@@ -1618,6 +1689,20 @@ void security_sb_clone_mnt_opts(const st
struct super_block *newsb);
int security_sb_parse_opts_str(char *options, struct security_mnt_opts *opts);

+int security_path_unlink(struct path *dir, struct dentry *dentry);
+int security_path_mkdir(struct path *dir, struct dentry *dentry, int mode);
+int security_path_rmdir(struct path *dir, struct dentry *dentry);
+int security_path_mknod(struct path *dir, struct dentry *dentry, int mode,
+ unsigned int dev);
+int security_path_truncate(struct path *path, loff_t length,
+ unsigned int time_attrs, struct file *filp);
+int security_path_symlink(struct path *dir, struct dentry *dentry,
+ const char *old_name);
+int security_path_link(struct dentry *old_dentry, struct path *new_dir,
+ struct dentry *new_dentry);
+int security_path_rename(struct path *old_dir, struct dentry *old_dentry,
+ struct path *new_dir, struct dentry *new_dentry);
+
int security_inode_alloc(struct inode *inode);
void security_inode_free(struct inode *inode);
int security_inode_init_security(struct inode *inode, struct inode *dir,
@@ -1949,6 +2034,56 @@ static inline int security_sb_parse_opts
return 0;
}

+static inline int security_path_unlink(struct path *dir, struct dentry *dentry)
+{
+ return 0;
+}
+
+static inline int security_path_mkdir(struct path *dir, struct dentry *dentry,
+ int mode)
+{
+ return 0;
+}
+
+static inline int security_path_rmdir(struct path *dir, struct dentry *dentry)
+{
+ return 0;
+}
+
+static inline int security_path_mknod(struct path *dir, struct dentry *dentry,
+ int mode, unsigned int dev)
+{
+ return 0;
+}
+
+static inline int security_path_truncate(struct path *path, loff_t length,
+ unsigned int time_attrs,
+ struct file *filp)
+{
+ return 0;
+}
+
+static inline int security_path_symlink(struct path *dir, struct dentry *dentry,
+ const char *old_name)
+{
+ return 0;
+}
+
+static inline int security_path_link(struct dentry *old_dentry,
+ struct path *new_dir,
+ struct dentry *new_dentry)
+{
+ return 0;
+}
+
+static inline int security_path_rename(struct path *old_dir,
+ struct dentry *old_dentry,
+ struct path *new_dir,
+ struct dentry *new_dentry)
+{
+ return 0;
+}
+
static inline int security_inode_alloc(struct inode *inode)
{
return 0;
--- linux-2.6.27-rc5.orig/net/unix/af_unix.c
+++ linux-2.6.27-rc5/net/unix/af_unix.c
@@ -827,7 +827,11 @@ static int unix_bind(struct socket *sock
err = mnt_want_write(nd.path.mnt);
if (err)
goto out_mknod_dput;
+ err = security_path_mknod(&nd.path, dentry, mode, 0);
+ if (err)
+ goto out_mknod_drop_write;
err = vfs_mknod(nd.path.dentry->d_inode, dentry, mode, 0);
+out_mknod_drop_write:
mnt_drop_write(nd.path.mnt);
if (err)
goto out_mknod_dput;
--- linux-2.6.27-rc5.orig/security/capability.c
+++ linux-2.6.27-rc5/security/capability.c
@@ -268,6 +268,51 @@ static void cap_inode_getsecid(const str
*secid = 0;
}

+static int cap_path_mknod(struct path *dir, struct dentry *dentry, int mode,
+ unsigned int dev)
+{
+ return 0;
+}
+
+static int cap_path_mkdir(struct path *dir, struct dentry *dentry, int mode)
+{
+ return 0;
+}
+
+static int cap_path_rmdir(struct path *dir, struct dentry *dentry)
+{
+ return 0;
+}
+
+static int cap_path_unlink(struct path *dir, struct dentry *dentry)
+{
+ return 0;
+}
+
+static int cap_path_symlink(struct path *dir, struct dentry *dentry,
+ const char *old_name)
+{
+ return 0;
+}
+
+static int cap_path_link(struct dentry *old_dentry, struct path *new_dir,
+ struct dentry *new_dentry)
+{
+ return 0;
+}
+
+static int cap_path_rename(struct path *old_path, struct dentry *old_dentry,
+ struct path *new_path, struct dentry *new_dentry)
+{
+ return 0;
+}
+
+static int cap_path_truncate(struct path *path, loff_t length,
+ unsigned int time_attrs, struct file *filp)
+{
+ return 0;
+}
+
static int cap_file_permission(struct file *file, int mask)
{
return 0;
@@ -877,6 +922,14 @@ void security_fixup_ops(struct security_
set_to_cap_if_null(ops, inode_setsecurity);
set_to_cap_if_null(ops, inode_listsecurity);
set_to_cap_if_null(ops, inode_getsecid);
+ set_to_cap_if_null(ops, path_mknod);
+ set_to_cap_if_null(ops, path_mkdir);
+ set_to_cap_if_null(ops, path_rmdir);
+ set_to_cap_if_null(ops, path_unlink);
+ set_to_cap_if_null(ops, path_symlink);
+ set_to_cap_if_null(ops, path_link);
+ set_to_cap_if_null(ops, path_rename);
+ set_to_cap_if_null(ops, path_truncate);
set_to_cap_if_null(ops, file_permission);
set_to_cap_if_null(ops, file_alloc_security);
set_to_cap_if_null(ops, file_free_security);
--- linux-2.6.27-rc5.orig/security/security.c
+++ linux-2.6.27-rc5/security/security.c
@@ -358,6 +358,69 @@ int security_inode_init_security(struct
}
EXPORT_SYMBOL(security_inode_init_security);

+int security_path_mknod(struct path *path, struct dentry *dentry, int mode,
+ unsigned int dev)
+{
+ if (unlikely(IS_PRIVATE(path->dentry->d_inode)))
+ return 0;
+ return security_ops->path_mknod(path, dentry, mode, dev);
+}
+
+int security_path_mkdir(struct path *path, struct dentry *dentry, int mode)
+{
+ if (unlikely(IS_PRIVATE(path->dentry->d_inode)))
+ return 0;
+ return security_ops->path_mkdir(path, dentry, mode);
+}
+
+int security_path_rmdir(struct path *path, struct dentry *dentry)
+{
+ if (unlikely(IS_PRIVATE(path->dentry->d_inode)))
+ return 0;
+ return security_ops->path_rmdir(path, dentry);
+}
+
+int security_path_unlink(struct path *path, struct dentry *dentry)
+{
+ if (unlikely(IS_PRIVATE(path->dentry->d_inode)))
+ return 0;
+ return security_ops->path_unlink(path, dentry);
+}
+
+int security_path_symlink(struct path *path, struct dentry *dentry,
+ const char *old_name)
+{
+ if (unlikely(IS_PRIVATE(path->dentry->d_inode)))
+ return 0;
+ return security_ops->path_symlink(path, dentry, old_name);
+}
+
+int security_path_link(struct dentry *old_dentry, struct path *new_dir,
+ struct dentry *new_dentry)
+{
+ if (unlikely(IS_PRIVATE(old_dentry->d_inode)))
+ return 0;
+ return security_ops->path_link(old_dentry, new_dir, new_dentry);
+}
+
+int security_path_rename(struct path *old_dir, struct dentry *old_dentry,
+ struct path *new_dir, struct dentry *new_dentry)
+{
+ if (unlikely(IS_PRIVATE(old_dentry->d_inode) ||
+ (new_dentry->d_inode && IS_PRIVATE(new_dentry->d_inode))))
+ return 0;
+ return security_ops->path_rename(old_dir, old_dentry, new_dir,
+ new_dentry);
+}
+
+int security_path_truncate(struct path *path, loff_t length,
+ unsigned int time_attrs, struct file *filp)
+{
+ if (unlikely(IS_PRIVATE(path->dentry->d_inode)))
+ return 0;
+ return security_ops->path_truncate(path, length, time_attrs, filp);
+}
+
int security_inode_create(struct inode *dir, struct dentry *dentry, int mode)
{
if (unlikely(IS_PRIVATE(dir)))

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