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Subject[TOMOYO #16 01/25] LSM: Add security_path_chmod() and security_path_chown().
This patch allows pathname based LSM modules to check chmod()/chown()
operations. Since notify_change() does not receive "struct vfsmount *",
we add security_path_chmod() and security_path_chown() to the caller of
notify_change().

These hooks are used by TOMOYO.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
---
fs/open.c | 24 ++++++++++++++++++++----
include/linux/security.h | 30 ++++++++++++++++++++++++++++++
security/capability.c | 13 +++++++++++++
security/security.c | 15 +++++++++++++++
4 files changed, 78 insertions(+), 4 deletions(-)
--- security-testing-2.6.orig/fs/open.c
+++ security-testing-2.6/fs/open.c
@@ -616,6 +616,9 @@ SYSCALL_DEFINE2(fchmod, unsigned int, fd
err = mnt_want_write_file(file);
if (err)
goto out_putf;
+ err = security_path_chmod(dentry, file->f_vfsmnt, mode);
+ if (err)
+ goto out_drop_write;
mutex_lock(&inode->i_mutex);
if (mode == (mode_t) -1)
mode = inode->i_mode;
@@ -623,6 +626,7 @@ SYSCALL_DEFINE2(fchmod, unsigned int, fd
newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
err = notify_change(dentry, &newattrs);
mutex_unlock(&inode->i_mutex);
+out_drop_write:
mnt_drop_write(file->f_path.mnt);
out_putf:
fput(file);
@@ -645,6 +649,9 @@ SYSCALL_DEFINE3(fchmodat, int, dfd, cons
error = mnt_want_write(path.mnt);
if (error)
goto dput_and_out;
+ error = security_path_chmod(path.dentry, path.mnt, mode);
+ if (error)
+ goto out_drop_write;
mutex_lock(&inode->i_mutex);
if (mode == (mode_t) -1)
mode = inode->i_mode;
@@ -652,6 +659,7 @@ SYSCALL_DEFINE3(fchmodat, int, dfd, cons
newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
error = notify_change(path.dentry, &newattrs);
mutex_unlock(&inode->i_mutex);
+out_drop_write:
mnt_drop_write(path.mnt);
dput_and_out:
path_put(&path);
@@ -700,7 +708,9 @@ SYSCALL_DEFINE3(chown, const char __user
error = mnt_want_write(path.mnt);
if (error)
goto out_release;
- error = chown_common(path.dentry, user, group);
+ error = security_path_chown(&path, user, group);
+ if (!error)
+ error = chown_common(path.dentry, user, group);
mnt_drop_write(path.mnt);
out_release:
path_put(&path);
@@ -725,7 +735,9 @@ SYSCALL_DEFINE5(fchownat, int, dfd, cons
error = mnt_want_write(path.mnt);
if (error)
goto out_release;
- error = chown_common(path.dentry, user, group);
+ error = security_path_chown(&path, user, group);
+ if (!error)
+ error = chown_common(path.dentry, user, group);
mnt_drop_write(path.mnt);
out_release:
path_put(&path);
@@ -744,7 +756,9 @@ SYSCALL_DEFINE3(lchown, const char __use
error = mnt_want_write(path.mnt);
if (error)
goto out_release;
- error = chown_common(path.dentry, user, group);
+ error = security_path_chown(&path, user, group);
+ if (!error)
+ error = chown_common(path.dentry, user, group);
mnt_drop_write(path.mnt);
out_release:
path_put(&path);
@@ -767,7 +781,9 @@ SYSCALL_DEFINE3(fchown, unsigned int, fd
goto out_fput;
dentry = file->f_path.dentry;
audit_inode(NULL, dentry);
- error = chown_common(dentry, user, group);
+ error = security_path_chown(&file->f_path, user, group);
+ if (!error)
+ error = chown_common(dentry, user, group);
mnt_drop_write(file->f_path.mnt);
out_fput:
fput(file);
--- security-testing-2.6.orig/include/linux/security.h
+++ security-testing-2.6/include/linux/security.h
@@ -447,6 +447,18 @@ static inline void security_free_mnt_opt
* @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.
+ * @path_chmod:
+ * Check for permission to change DAC's permission of a file or directory.
+ * @dentry contains the dentry structure.
+ * @mnt contains the vfsmnt structure.
+ * @mode contains DAC's mode.
+ * Return 0 if permission is granted.
+ * @path_chown:
+ * Check for permission to change owner/group of a file or directory.
+ * @path contains the path structure.
+ * @uid contains new owner's ID.
+ * @gid contains new group's ID.
+ * 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.
@@ -1488,6 +1500,9 @@ struct security_operations {
struct dentry *new_dentry);
int (*path_rename) (struct path *old_dir, struct dentry *old_dentry,
struct path *new_dir, struct dentry *new_dentry);
+ int (*path_chmod) (struct dentry *dentry, struct vfsmount *mnt,
+ mode_t mode);
+ int (*path_chown) (struct path *path, uid_t uid, gid_t gid);
#endif

int (*inode_alloc_security) (struct inode *inode);
@@ -2952,6 +2967,9 @@ int security_path_link(struct dentry *ol
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_path_chmod(struct dentry *dentry, struct vfsmount *mnt,
+ mode_t mode);
+int security_path_chown(struct path *path, uid_t uid, gid_t gid);
#else /* CONFIG_SECURITY_PATH */
static inline int security_path_unlink(struct path *dir, struct dentry *dentry)
{
@@ -3001,6 +3019,18 @@ static inline int security_path_rename(s
{
return 0;
}
+
+static inline int security_path_chmod(struct dentry *dentry,
+ struct vfsmount *mnt,
+ mode_t mode)
+{
+ return 0;
+}
+
+static inline int security_path_chown(struct path *path, uid_t uid, gid_t gid)
+{
+ return 0;
+}
#endif /* CONFIG_SECURITY_PATH */

#ifdef CONFIG_KEYS
--- security-testing-2.6.orig/security/capability.c
+++ security-testing-2.6/security/capability.c
@@ -308,6 +308,17 @@ static int cap_path_truncate(struct path
{
return 0;
}
+
+static int cap_path_chmod(struct dentry *dentry, struct vfsmount *mnt,
+ mode_t mode)
+{
+ return 0;
+}
+
+static int cap_path_chown(struct path *path, uid_t uid, gid_t gid)
+{
+ return 0;
+}
#endif

static int cap_file_permission(struct file *file, int mask)
@@ -977,6 +988,8 @@ void security_fixup_ops(struct security_
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, path_chmod);
+ set_to_cap_if_null(ops, path_chown);
#endif
set_to_cap_if_null(ops, file_permission);
set_to_cap_if_null(ops, file_alloc_security);
--- security-testing-2.6.orig/security/security.c
+++ security-testing-2.6/security/security.c
@@ -434,6 +434,21 @@ int security_path_truncate(struct path *
return 0;
return security_ops->path_truncate(path, length, time_attrs);
}
+
+int security_path_chmod(struct dentry *dentry, struct vfsmount *mnt,
+ mode_t mode)
+{
+ if (unlikely(IS_PRIVATE(dentry->d_inode)))
+ return 0;
+ return security_ops->path_chmod(dentry, mnt, mode);
+}
+
+int security_path_chown(struct path *path, uid_t uid, gid_t gid)
+{
+ if (unlikely(IS_PRIVATE(path->dentry->d_inode)))
+ return 0;
+ return security_ops->path_chown(path, uid, gid);
+}
#endif

int security_inode_create(struct inode *dir, struct dentry *dentry, int mode)
--


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