| Message ID | 20200621222135.9136-1-kpsingh@chromium.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | security: Fix hook iteration and default value for inode_copy_up_xattr | expand |
On Mon, 22 Jun 2020, KP Singh wrote: > From: KP Singh <kpsingh@google.com> > > inode_copy_up_xattr returns 0 to indicate the acceptance of the xattr > and 1 to reject it. If the LSM does not know about the xattr, it's > expected to return -EOPNOTSUPP, which is the correct default value for > this hook. BPF LSM, currently, uses 0 as the default value and thereby > falsely allows all overlay fs xattributes to be copied up. > > The iteration logic is also updated from the "bail-on-fail" > call_int_hook to continue on the non-decisive -EOPNOTSUPP and bail out > on other values. > > Fixes: 98e828a0650f ("security: Refactor declaration of LSM hooks") > Signed-off-by: KP Singh <kpsingh@google.com> Applied to git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security.git fixes-v5.8 > --- > include/linux/lsm_hook_defs.h | 2 +- > security/security.c | 17 ++++++++++++++++- > 2 files changed, 17 insertions(+), 2 deletions(-) > > diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h > index 6791813cd439..f4b2e54162ae 100644 > --- a/include/linux/lsm_hook_defs.h > +++ b/include/linux/lsm_hook_defs.h > @@ -150,7 +150,7 @@ LSM_HOOK(int, 0, inode_listsecurity, struct inode *inode, char *buffer, > size_t buffer_size) > LSM_HOOK(void, LSM_RET_VOID, inode_getsecid, struct inode *inode, u32 *secid) > LSM_HOOK(int, 0, inode_copy_up, struct dentry *src, struct cred **new) > -LSM_HOOK(int, 0, inode_copy_up_xattr, const char *name) > +LSM_HOOK(int, -EOPNOTSUPP, inode_copy_up_xattr, const char *name) > LSM_HOOK(int, 0, kernfs_init_security, struct kernfs_node *kn_dir, > struct kernfs_node *kn) > LSM_HOOK(int, 0, file_permission, struct file *file, int mask) > diff --git a/security/security.c b/security/security.c > index 0ce3e73edd42..70a7ad357bc6 100644 > --- a/security/security.c > +++ b/security/security.c > @@ -1414,7 +1414,22 @@ EXPORT_SYMBOL(security_inode_copy_up); > > int security_inode_copy_up_xattr(const char *name) > { > - return call_int_hook(inode_copy_up_xattr, -EOPNOTSUPP, name); > + struct security_hook_list *hp; > + int rc; > + > + /* > + * The implementation can return 0 (accept the xattr), 1 (discard the > + * xattr), -EOPNOTSUPP if it does not know anything about the xattr or > + * any other error code incase of an error. > + */ > + hlist_for_each_entry(hp, > + &security_hook_heads.inode_copy_up_xattr, list) { > + rc = hp->hook.inode_copy_up_xattr(name); > + if (rc != LSM_RET_DEFAULT(inode_copy_up_xattr)) > + return rc; > + } > + > + return LSM_RET_DEFAULT(inode_copy_up_xattr); > } > EXPORT_SYMBOL(security_inode_copy_up_xattr); > >
diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index 6791813cd439..f4b2e54162ae 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -150,7 +150,7 @@ LSM_HOOK(int, 0, inode_listsecurity, struct inode *inode, char *buffer, size_t buffer_size) LSM_HOOK(void, LSM_RET_VOID, inode_getsecid, struct inode *inode, u32 *secid) LSM_HOOK(int, 0, inode_copy_up, struct dentry *src, struct cred **new) -LSM_HOOK(int, 0, inode_copy_up_xattr, const char *name) +LSM_HOOK(int, -EOPNOTSUPP, inode_copy_up_xattr, const char *name) LSM_HOOK(int, 0, kernfs_init_security, struct kernfs_node *kn_dir, struct kernfs_node *kn) LSM_HOOK(int, 0, file_permission, struct file *file, int mask) diff --git a/security/security.c b/security/security.c index 0ce3e73edd42..70a7ad357bc6 100644 --- a/security/security.c +++ b/security/security.c @@ -1414,7 +1414,22 @@ EXPORT_SYMBOL(security_inode_copy_up); int security_inode_copy_up_xattr(const char *name) { - return call_int_hook(inode_copy_up_xattr, -EOPNOTSUPP, name); + struct security_hook_list *hp; + int rc; + + /* + * The implementation can return 0 (accept the xattr), 1 (discard the + * xattr), -EOPNOTSUPP if it does not know anything about the xattr or + * any other error code incase of an error. + */ + hlist_for_each_entry(hp, + &security_hook_heads.inode_copy_up_xattr, list) { + rc = hp->hook.inode_copy_up_xattr(name); + if (rc != LSM_RET_DEFAULT(inode_copy_up_xattr)) + return rc; + } + + return LSM_RET_DEFAULT(inode_copy_up_xattr); } EXPORT_SYMBOL(security_inode_copy_up_xattr);