On Tue, 30 Sep 2008 19:33:32 PDT, Casey Schaufler said:
> I have always believed that MAC should come first, then DAC, because
> MAC may care if you can see the mode bits. The current DAC before MAC
> is an artifact of the desire for the LSM to behave cleanly as a
> strictly additional mechanism. From an ideal security perspective
> MAC should be first, but the pragmatic DAC first isn't going to cause
> too much grief. If Tomoyo wants to do what I think is the right thing,
> well, it's OK with me.
I'm OK with the MAC going first as well - but unless/until we convert the
rest of the kernel to do MAC-before-DAC, somebody better leave a comment:
/* Yes, this one spot *is* doing MAC-first intentionally */
or similar, just so we don't keep getting patches to "fix" it to DAC-first...
(And yes, newbie janitors *will* submit patches like that - how many times
have we had the 'ndiswrapper-taint-flag' flame war now?)
[email protected] wrote:
> On Tue, 30 Sep 2008 19:33:32 PDT, Casey Schaufler said:
>> I have always believed that MAC should come first, then DAC, because
>> MAC may care if you can see the mode bits. The current DAC before MAC
>> is an artifact of the desire for the LSM to behave cleanly as a
>> strictly additional mechanism. From an ideal security perspective
>> MAC should be first, but the pragmatic DAC first isn't going to cause
>> too much grief. If Tomoyo wants to do what I think is the right thing,
>> well, it's OK with me.
> I'm OK with the MAC going first as well
Current implementation is as follows.
- security_path_*: MAC before DAC
- security_inode_*: DAC before MAC
I can understand Casey and Valdis' MAC first approach from the ideal
security perspective. However, from the pragmatic perspective, we
prefer DAC before MAC approach as SELinux does. This approach doesn't
change error code returned to callers if requested access is denied
by DAC.
Regards,
Quoting Kentaro Takeda ([email protected]):
> [email protected] wrote:
> > On Tue, 30 Sep 2008 19:33:32 PDT, Casey Schaufler said:
> >> I have always believed that MAC should come first, then DAC, because
> >> MAC may care if you can see the mode bits. The current DAC before MAC
> >> is an artifact of the desire for the LSM to behave cleanly as a
> >> strictly additional mechanism. From an ideal security perspective
> >> MAC should be first, but the pragmatic DAC first isn't going to cause
> >> too much grief. If Tomoyo wants to do what I think is the right thing,
> >> well, it's OK with me.
> > I'm OK with the MAC going first as well
> Current implementation is as follows.
> - security_path_*: MAC before DAC
> - security_inode_*: DAC before MAC
> I can understand Casey and Valdis' MAC first approach from the ideal
> security perspective. However, from the pragmatic perspective, we
> prefer DAC before MAC approach as SELinux does. This approach doesn't
> change error code returned to callers if requested access is denied
> by DAC.
>
> Regards,
I suppose you could do something like define both _path and _inode,
save away your result from the _path hook but always return 0, there,
then if you'd saved off an error and you make it to the _inode hook,
return the error there...
-serge
Serge E. Hallyn wrote:
> I suppose you could do something like define both _path and _inode,
> save away your result from the _path hook but always return 0, there,
> then if you'd saved off an error and you make it to the _inode hook,
> return the error there...
You mean do MAC checks in security_path_*() and return error code of
security_path_*() in security_inode_*()? Then, method for passing the
error code to security_inode_*() is a problem.
It was possible to store the error code into current->security->
something. But now, it is impossible to store the error code into
current->cred->security->something because current->cred is shared by
multiple processes. To solve this problem, we everytime need to copy
current->cred in security_path_*() and we need a new hook called just
after returning from vfs_* (like mnt_drop_write()) for clearing the
error code.
Or, another way is to pass the error code as a vfs_*() parameter.
What do you think these approaches?
Regards,
Quoting Kentaro Takeda ([email protected]):
> Serge E. Hallyn wrote:
> > I suppose you could do something like define both _path and _inode,
> > save away your result from the _path hook but always return 0, there,
> > then if you'd saved off an error and you make it to the _inode hook,
> > return the error there...
> You mean do MAC checks in security_path_*() and return error code of
> security_path_*() in security_inode_*()? Then, method for passing the
> error code to security_inode_*() is a problem.
>
> It was possible to store the error code into current->security->
> something. But now, it is impossible to store the error code into
> current->cred->security->something because current->cred is shared by
> multiple processes. To solve this problem, we everytime need to copy
> current->cred in security_path_*() and we need a new hook called just
> after returning from vfs_* (like mnt_drop_write()) for clearing the
> error code.
>
> Or, another way is to pass the error code as a vfs_*() parameter.
>
> What do you think these approaches?
Just keep your own hash table.
-serge
Serge E. Hallyn wrote:
> Just keep your own hash table.
I see, then we want one more LSM hook for clearing the hash table
after returing from vfs_*().
foo() {
error = security_path_foo(); /* save result in the hash table */
error = vfs_foo(); /* fetch from the hash table in security_inode_*() */
security_path_clear(); /* clear the hash table */
}
Is it acceptable?
Regards,
Quoting Kentaro Takeda ([email protected]):
> Serge E. Hallyn wrote:
> > Just keep your own hash table.
> I see, then we want one more LSM hook for clearing the hash table
> after returing from vfs_*().
>
> foo() {
> error = security_path_foo(); /* save result in the hash table */
> error = vfs_foo(); /* fetch from the hash table in security_inode_*() */
> security_path_clear(); /* clear the hash table */
> }
>
> Is it acceptable?
Why can't you just clear the value during security_inode_foo()?
Note I'm seeing this as a way for Tomoyo to temporarily (maybe) work
around the mis-placement of the security_path_foo() hooks. I don't want
to add security_path_clear() hooks to "legitimize" the workaround. I'd
rather Tomoyo and Apparmor folks keep looking for a better way to get
real DAC-before-MAC.
> Regards,
>
>
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Serge E. Hallyn wrote:
> Why can't you just clear the value during security_inode_foo()?
We need a new hook for clearing the value since security_inode_*()
are not always called after security_path_*() .
> Note I'm seeing this as a way for Tomoyo to temporarily (maybe) work
> around the mis-placement of the security_path_foo() hooks. I don't want
> to add security_path_clear() hooks to "legitimize" the workaround. I'd
> rather Tomoyo and Apparmor folks keep looking for a better way to get
> real DAC-before-MAC.
Hmm, I can understand your opinion. The best way for AppArmor and
TOMOYO is to pass vfsmount to vfs_*() and security_inode_*() . This
approach has no DAC-before-MAC problem. However, it is clearly
opposed by Al because of layering. So, we are going forward
security_path_*() approach, which Al advised us.
Since vfsmount is only available outside vfs_*() (and vfs_*() perform
DAC), we cannot conceive another place now... Where do you think the
right place to introduce security_path_*() hooks is?
Regards,
Quoting Kentaro Takeda ([email protected]):
> Serge E. Hallyn wrote:
> > Why can't you just clear the value during security_inode_foo()?
> We need a new hook for clearing the value since security_inode_*()
> are not always called after security_path_*() .
Heh, obviously you're right :)
So I'd recommend floating your security_path_clear() patch with a clear
description about the DAC-before-MAC property which you are maintaining.
Someone may come up with a better overall solution, but we're unlikely
to hear it until you try to push your patch.
-serge
> > Note I'm seeing this as a way for Tomoyo to temporarily (maybe) work
> > around the mis-placement of the security_path_foo() hooks. I don't want
> > to add security_path_clear() hooks to "legitimize" the workaround. I'd
> > rather Tomoyo and Apparmor folks keep looking for a better way to get
> > real DAC-before-MAC.
> Hmm, I can understand your opinion. The best way for AppArmor and
> TOMOYO is to pass vfsmount to vfs_*() and security_inode_*() . This
> approach has no DAC-before-MAC problem. However, it is clearly
> opposed by Al because of layering. So, we are going forward
> security_path_*() approach, which Al advised us.
>
> Since vfsmount is only available outside vfs_*() (and vfs_*() perform
> DAC), we cannot conceive another place now... Where do you think the
> right place to introduce security_path_*() hooks is?
>
> Regards,
>
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Serge E. Hallyn wrote:
> So I'd recommend floating your security_path_clear() patch with a clear
> description about the DAC-before-MAC property which you are maintaining.
> Someone may come up with a better overall solution, but we're unlikely
> to hear it until you try to push your patch.
Serge, thank you for your patient advisement. :)
Here is the patch with all changes against LSM interface.
Al, is this patch acceptable?
---
----- What is this patch for? -----
There are security_inode_*() LSM hooks for attribute-based MAC, but they are not
suitable for pathname-based MAC because they don't receive "struct vfsmount"
information.
----- How this patch was developed? -----
Two pathname-based MACs, AppArmor and TOMOYO Linux, are trying to merge
upstream. But because of "struct vfsmount" problem, they have been unable to
merge upstream.
Here are the list of approaches and the reasons of denial.
(1) Not using LSM
http://lwn.net/Articles/277833/
This approach was rejected because security modules should use LSM because the
whole idea behind LSM was to have a single set of hooks for all security
modules; if every module now adds its own set of hooks, that purpose will have
been defeated and the kernel will turn into a big mess of security hooks.
(2) Retrieving "struct vfsmount" from "struct task_struct".
http://lkml.org/lkml/2007/11/5/388
Since "struct task_struct" contains list of "struct vfsmount",
"struct vfsmount" which corresponds to "struct dentry" can be retrieved from
the list unless "mount --bind" is used.
This approach turned out to cause a critical problem that getting namespace_sem
lock from security_inode_*() triggers AB-BA deadlock.
(3) Adding "struct vfsmount" parameter to VFS helper functions.
http://lkml.org/lkml/2008/5/29/207
This approach adds "struct vfsmount" to VFS helper functions (e.g. vfs_mkdir()
and vfs_symlink()) and LSM hooks inside VFS helper functions. This approach is
helpful for not only AppArmor and TOMOYO Linux 2.x but also SELinux and
auditing purpose, for this approach allows existent LSM users to use pathnames
in their access control and audit logs.
This approach was rejected by Al Viro, the VFS maintainer, because he thinks
individual filesystem should remain "struct vfsmount"-unaware and VFS helper
functions should not receive "struct vfsmount".
Al Viro also suggested to move existing security_inode_*() to out of VFS
helper functions so that security_inode_*() can receive "struct vfsmount"
without modifying VFS helper functions, but this suggestion was opposed by
Stephen Smalley because changing the order of permission checks (i.e.
MAC checks before DAC checks) is not acceptable.
(4) Passing "struct vfsmount" via "struct task_struct".
http://lkml.org/lkml/2007/11/16/157
Since we didn't understand the reason why accessing "struct vfsmount" from
LSM hooks inside VFS helper functions is not acceptable, we thought the reason
why VFS helper functions don't receive "struct vfsmount" is the amount of
modifications needed to do so. Thus, we proposed to pass "struct vfsmount" via
"struct task_struct" so that modifications remain minimal.
This approach was rejected because this is an abuse of "struct task_struct".
(5) Remembering pathname of "struct vfsmount" via "struct task_struct".
http://lkml.org/lkml/2008/8/19/16
Since pathname of a "struct dentry" up to the mount point can be calculated
without "struct vfsmount", absolute pathname of a "struct dentry" can be
calculated if "struct task_struct" can remember absolute pathname of a
"struct vfsmount" which corresponds to "struct dentry".
As we now understand that Al Viro is opposing to access "struct vfsmount" from
LSM hooks inside VFS helper functions, we gave up delivering "struct vfsmount"
to LSM hooks inside VFS helper functions.
Kernel 2.6.26 introduced read-only bind mount feature, and hooks for that
feature (i.e. mnt_want_write() and mnt_drop_write()) were inserted around
VFS helper functions call. Since mnt_want_write() receives "struct vfsmount"
which corresponds to "struct dentry" that will be passed to subsequent VFS
helper functions call, we associated pathname of "struct vfsmount" with
"struct task_struct" instead of associating "struct vfsmount" itself.
This approach was not explicitly rejected, but there seems to be performance
problem.
(6) Introducing new LSM hooks.
(this patch)
We understand that adding new LSM hooks which receive "struct vfsmount" outside
VFS helper functions is the most straightforward approach. This approach has
less impact to existing LSM module and no impact to VFS helper functions.
Signed-off-by: Kentaro Takeda <[email protected]>
Signed-off-by: Tetsuo Handa <[email protected]>
Signed-off-by: Toshiharu Harada <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Crispin Cowan <[email protected]>
Cc: Stephen Smalley <[email protected]>
Cc: Casey Schaufler <[email protected]>
Cc: James Morris <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
---
fs/namei.c | 46 ++++++++++++++
fs/open.c | 5 +
include/linux/security.h | 151 +++++++++++++++++++++++++++++++++++++++++++++++
net/unix/af_unix.c | 5 +
security/Kconfig | 9 ++
security/capability.c | 63 +++++++++++++++++++
security/security.c | 73 ++++++++++++++++++++++
7 files changed, 352 insertions(+)
--- linux-next.orig/fs/namei.c
+++ linux-next/fs/namei.c
@@ -1571,12 +1571,17 @@ 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);
error = do_truncate(dentry, 0,
ATTR_MTIME|ATTR_CTIME|ATTR_OPEN,
NULL);
+ security_path_clear();
}
put_write_access(inode);
if (error)
@@ -1601,7 +1606,12 @@ 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);
+ security_path_clear();
+out_unlock:
mutex_unlock(&dir->d_inode->i_mutex);
dput(nd->path.dentry);
nd->path.dentry = path->dentry;
@@ -2014,6 +2024,9 @@ 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);
@@ -2026,6 +2039,8 @@ asmlinkage long sys_mknodat(int dfd, con
error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0);
break;
}
+ security_path_clear();
+out_drop_write:
mnt_drop_write(nd.path.mnt);
out_dput:
dput(dentry);
@@ -2085,7 +2100,12 @@ 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);
+ security_path_clear();
+out_drop_write:
mnt_drop_write(nd.path.mnt);
out_dput:
dput(dentry);
@@ -2192,7 +2212,12 @@ 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);
+ security_path_clear();
+exit4:
mnt_drop_write(nd.path.mnt);
exit3:
dput(dentry);
@@ -2274,7 +2299,12 @@ 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);
+ security_path_clear();
+exit3:
mnt_drop_write(nd.path.mnt);
exit2:
dput(dentry);
@@ -2355,7 +2385,12 @@ 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);
+ security_path_clear();
+out_drop_write:
mnt_drop_write(nd.path.mnt);
out_dput:
dput(dentry);
@@ -2452,7 +2487,12 @@ 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);
+ security_path_clear();
+out_drop_write:
mnt_drop_write(nd.path.mnt);
out_dput:
dput(new_dentry);
@@ -2684,8 +2724,14 @@ 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);
+ security_path_clear();
+exit6:
mnt_drop_write(oldnd.path.mnt);
exit5:
dput(new_dentry);
--- linux-next.orig/fs/open.c
+++ linux-next/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-next.orig/include/linux/security.h
+++ linux-next/include/linux/security.h
@@ -331,17 +331,37 @@ 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.
@@ -349,11 +369,25 @@ 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
@@ -364,6 +398,15 @@ 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.
@@ -371,6 +414,13 @@ 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.
@@ -399,6 +449,13 @@ 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
@@ -466,6 +523,12 @@ static inline void security_free_mnt_opt
* @inode contains a pointer to the inode.
* @secid contains a pointer to the location where result will be saved.
* In case of failure, @secid will be set to zero.
+ * @path_clear:
+ * Clear error code stored by security_path_*() in case
+ * security_inode_*() was not called when DAC returned an error.
+ * This hook allows LSM modules which use security_path_*() defer
+ * returning LSM's error code till security_inode_*() is called so that
+ * DAC's error (if any) is returned to the caller instead of LSM's error.
*
* Security hooks for file operations
*
@@ -1327,6 +1390,23 @@ struct security_operations {
struct super_block *newsb);
int (*sb_parse_opts_str) (char *options, struct security_mnt_opts *opts);
+#ifdef CONFIG_SECURITY_PATH
+ 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);
+ void (*path_clear) (void);
+#endif
+
int (*inode_alloc_security) (struct inode *inode);
void (*inode_free_security) (struct inode *inode);
int (*inode_init_security) (struct inode *inode, struct inode *dir,
@@ -2685,6 +2765,77 @@ static inline void security_skb_classify
#endif /* CONFIG_SECURITY_NETWORK_XFRM */
+#ifdef CONFIG_SECURITY_PATH
+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);
+void security_path_clear(void);
+#else /* CONFIG_SECURITY_PATH */
+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 void security_path_clear(void)
+{
+}
+#endif /* CONFIG_SECURITY_PATH */
+
#ifdef CONFIG_KEYS
#ifdef CONFIG_SECURITY
--- linux-next.orig/net/unix/af_unix.c
+++ linux-next/net/unix/af_unix.c
@@ -828,7 +828,12 @@ 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);
+ security_path_clear();
+out_mknod_drop_write:
mnt_drop_write(nd.path.mnt);
if (err)
goto out_mknod_dput;
--- linux-next.orig/security/Kconfig
+++ linux-next/security/Kconfig
@@ -81,6 +81,15 @@ config SECURITY_NETWORK_XFRM
IPSec.
If you are unsure how to answer this question, answer N.
+config SECURITY_PATH
+ bool "Security hooks for pathname based access control"
+ depends on SECURITY
+ help
+ This enables the security hooks for pathname based access control.
+ If enabled, a security module can use these hooks to
+ implement pathname based access controls.
+ If you are unsure how to answer this question, answer N.
+
config SECURITY_FILE_CAPABILITIES
bool "File POSIX Capabilities"
default n
--- linux-next.orig/security/capability.c
+++ linux-next/security/capability.c
@@ -263,6 +263,58 @@ static void cap_inode_getsecid(const str
*secid = 0;
}
+#ifdef CONFIG_SECURITY_PATH
+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 void cap_path_clear(void)
+{
+}
+
+#endif
+
static int cap_file_permission(struct file *file, int mask)
{
return 0;
@@ -883,6 +935,17 @@ 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);
+#ifdef CONFIG_SECURITY_PATH
+ 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, path_clear);
+#endif
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-next.orig/security/security.c
+++ linux-next/security/security.c
@@ -341,6 +341,79 @@ int security_inode_init_security(struct
}
EXPORT_SYMBOL(security_inode_init_security);
+#ifdef CONFIG_SECURITY_PATH
+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);
+}
+EXPORT_SYMBOL(security_path_mknod);
+
+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);
+}
+
+void security_path_clear(void)
+{
+ return security_ops->path_clear();
+}
+EXPORT_SYMBOL(security_path_clear);
+
+#endif
+
int security_inode_create(struct inode *dir, struct dentry *dentry, int mode)
{
if (unlikely(IS_PRIVATE(dir)))