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Message-ID: <20240223172513.4049959-3-stefanb@linux.ibm.com>
Date: Fri, 23 Feb 2024 12:25:05 -0500
From: Stefan Berger <stefanb@...ux.ibm.com>
To: linux-integrity@...r.kernel.org, linux-security-module@...r.kernel.org,
linux-unionfs@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, paul@...l-moore.com, jmorris@...ei.org,
serge@...lyn.com, zohar@...ux.ibm.com, roberto.sassu@...wei.com,
amir73il@...il.com, brauner@...nel.org, miklos@...redi.hu,
Stefan Berger <stefanb@...ux.ibm.com>
Subject: [PATCH v3 02/10] security: allow finer granularity in permitting copy-up of security xattrs
Copying up xattrs is solely based on the security xattr name. For finer
granularity add a dentry parameter to the security_inode_copy_up_xattr
hook definition, allowing decisions to be based on the xattr content as
well.
Co-developed-by: Mimi Zohar <zohar@...ux.ibm.com>
Signed-off-by: Stefan Berger <stefanb@...ux.ibm.com>
Acked-by: Amir Goldstein <amir73il@...il.com>
---
fs/overlayfs/copy_up.c | 2 +-
include/linux/lsm_hook_defs.h | 3 ++-
include/linux/security.h | 4 ++--
security/integrity/evm/evm_main.c | 2 +-
security/security.c | 5 +++--
security/selinux/hooks.c | 2 +-
security/smack/smack_lsm.c | 2 +-
7 files changed, 11 insertions(+), 9 deletions(-)
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index b8e25ca51016..bd9ddcefb7a7 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -114,7 +114,7 @@ int ovl_copy_xattr(struct super_block *sb, const struct path *oldpath, struct de
if (ovl_is_private_xattr(sb, name))
continue;
- error = security_inode_copy_up_xattr(name);
+ error = security_inode_copy_up_xattr(old, name);
if (error < 0 && error != -EOPNOTSUPP)
break;
if (error == 1) {
diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index 7e4683035d34..c538d39dd9a9 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -176,7 +176,8 @@ 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, -EOPNOTSUPP, inode_copy_up_xattr, const char *name)
+LSM_HOOK(int, -EOPNOTSUPP, inode_copy_up_xattr, struct dentry *src,
+ 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/include/linux/security.h b/include/linux/security.h
index 8436f9abf43d..2553a4f4b726 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -397,7 +397,7 @@ int security_inode_setsecurity(struct inode *inode, const char *name, const void
int security_inode_listsecurity(struct inode *inode, char *buffer, size_t buffer_size);
void security_inode_getsecid(struct inode *inode, u32 *secid);
int security_inode_copy_up(struct dentry *src, struct cred **new);
-int security_inode_copy_up_xattr(const char *name);
+int security_inode_copy_up_xattr(struct dentry *src, const char *name);
int security_kernfs_init_security(struct kernfs_node *kn_dir,
struct kernfs_node *kn);
int security_file_permission(struct file *file, int mask);
@@ -1015,7 +1015,7 @@ static inline int security_kernfs_init_security(struct kernfs_node *kn_dir,
return 0;
}
-static inline int security_inode_copy_up_xattr(const char *name)
+static inline int security_inode_copy_up_xattr(struct dentry *src, const char *name)
{
return -EOPNOTSUPP;
}
diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c
index 81dbade5b9b3..b0a862bfd74a 100644
--- a/security/integrity/evm/evm_main.c
+++ b/security/integrity/evm/evm_main.c
@@ -946,7 +946,7 @@ static void evm_inode_post_setattr(struct mnt_idmap *idmap,
evm_update_evmxattr(dentry, NULL, NULL, 0);
}
-static int evm_inode_copy_up_xattr(const char *name)
+static int evm_inode_copy_up_xattr(struct dentry *src, const char *name)
{
if (strcmp(name, XATTR_NAME_EVM) == 0)
return 1; /* Discard */
diff --git a/security/security.c b/security/security.c
index b95772333d05..8d8b89e6b5d9 100644
--- a/security/security.c
+++ b/security/security.c
@@ -2622,6 +2622,7 @@ EXPORT_SYMBOL(security_inode_copy_up);
/**
* security_inode_copy_up_xattr() - Filter xattrs in an overlayfs copy-up op
+ * @src: union dentry of copy-up file
* @name: xattr name
*
* Filter the xattrs being copied up when a unioned file is copied up from a
@@ -2632,7 +2633,7 @@ EXPORT_SYMBOL(security_inode_copy_up);
* if the security module does not know about attribute, or a negative
* error code to abort the copy up.
*/
-int security_inode_copy_up_xattr(const char *name)
+int security_inode_copy_up_xattr(struct dentry *src, const char *name)
{
int rc;
@@ -2641,7 +2642,7 @@ int security_inode_copy_up_xattr(const char *name)
* xattr), -EOPNOTSUPP if it does not know anything about the xattr or
* any other error code in case of an error.
*/
- rc = call_int_hook(inode_copy_up_xattr, name);
+ rc = call_int_hook(inode_copy_up_xattr, src, name);
if (rc != LSM_RET_DEFAULT(inode_copy_up_xattr))
return rc;
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index cedb4cbf072e..1d2395d8bba7 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3531,7 +3531,7 @@ static int selinux_inode_copy_up(struct dentry *src, struct cred **new)
return 0;
}
-static int selinux_inode_copy_up_xattr(const char *name)
+static int selinux_inode_copy_up_xattr(struct dentry *dentry, const char *name)
{
/* The copy_up hook above sets the initial context on an inode, but we
* don't then want to overwrite it by blindly copying all the lower
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 1b6abfdf7173..972d50e3f266 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -4875,7 +4875,7 @@ static int smack_inode_copy_up(struct dentry *dentry, struct cred **new)
return 0;
}
-static int smack_inode_copy_up_xattr(const char *name)
+static int smack_inode_copy_up_xattr(struct dentry *src, const char *name)
{
/*
* Return 1 if this is the smack access Smack attribute.
--
2.43.0
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