[PATCH bpf-next v4 05/20] lsm: Refactor return value of LSM hook inode_copy_up_xattr

Xu Kuohai
2024-07-11T11:14:00Z

From: Xu Kuohai <xukuohai@huawei.com>

To be consistent with most LSM hooks, convert the return value of
hook inode_copy_up_xattr to 0 or a negative error code.

Before:
- Hook inode_copy_up_xattr returns 0 when accepting xattr, 1 when
discarding xattr, -EOPNOTSUPP if it does not know xattr, or any
other negative error code otherwise.

After:
- Hook inode_copy_up_xattr returns 0 when accepting xattr, *-ECANCELED*
when discarding xattr, -EOPNOTSUPP if it does not know xattr, or
any other negative error code otherwise.

Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
---
fs/overlayfs/copy_up.c | 6 +++---
security/integrity/evm/evm_main.c | 2 +-
security/security.c | 12 ++++++------
security/selinux/hooks.c | 4 ++--
security/smack/smack_lsm.c | 6 +++---
5 files changed, 15 insertions(+), 15 deletions(-)

diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index a5ef2005a2cc..337a5be99ac9 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -115,12 +115,12 @@ int ovl_copy_xattr(struct super_block *sb, const struct path *oldpath, struct de
continue;

error = security_inode_copy_up_xattr(old, name);
- if (error < 0 && error != -EOPNOTSUPP)
- break;
- if (error == 1) {
+ if (error == -ECANCELED) {
error = 0;
continue; /* Discard */
}
+ if (error < 0 && error != -EOPNOTSUPP)
+ break;

if (is_posix_acl_xattr(name)) {
error = ovl_copy_acl(OVL_FS(sb), oldpath, new, name);
diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c
index 62fe66dd53ce..6924ed508ebd 100644
--- a/security/integrity/evm/evm_main.c
+++ b/security/integrity/evm/evm_main.c
@@ -1000,7 +1000,7 @@ static int evm_inode_copy_up_xattr(struct dentry *src, const char *name)
case EVM_XATTR_HMAC:
case EVM_IMA_XATTR_DIGSIG:
default:
- rc = 1; /* discard */
+ rc = -ECANCELED; /* discard */
}

kfree(xattr_data);
diff --git a/security/security.c b/security/security.c
index 26eea8f4cd74..12215ca286af 100644
--- a/security/security.c
+++ b/security/security.c
@@ -2675,18 +2675,18 @@ EXPORT_SYMBOL(security_inode_copy_up);
* lower layer to the union/overlay layer. The caller is responsible for
* reading and writing the xattrs, this hook is merely a filter.
*
- * Return: Returns 0 to accept the xattr, 1 to discard the xattr, -EOPNOTSUPP
- * if the security module does not know about attribute, or a negative
- * error code to abort the copy up.
+ * Return: Returns 0 to accept the xattr, -ECANCELED to discard the xattr,
+ * -EOPNOTSUPP 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(struct dentry *src, const char *name)
{
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 in case of an error.
+ * The implementation can return 0 (accept the xattr), -ECANCELED
+ * (discard the 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, src, name);
if (rc != LSM_RET_DEFAULT(inode_copy_up_xattr))
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 5dedd3917d57..f9a6637dfd78 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3528,8 +3528,8 @@ static int selinux_inode_copy_up_xattr(struct dentry *dentry, const char *name)
* xattrs up. Instead, filter out SELinux-related xattrs following
* policy load.
*/
- if (selinux_initialized() && strcmp(name, XATTR_NAME_SELINUX) == 0)
- return 1; /* Discard */
+ if (selinux_initialized() && !strcmp(name, XATTR_NAME_SELINUX))
+ return -ECANCELED; /* Discard */
/*
* Any other attribute apart from SELINUX is not claimed, supported
* by selinux.
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 6f73906bf7ea..ae8f1c2d0ca6 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -4893,10 +4893,10 @@ static int smack_inode_copy_up(struct dentry *dentry, struct cred **new)
static int smack_inode_copy_up_xattr(struct dentry *src, const char *name)
{
/*
- * Return 1 if this is the smack access Smack attribute.
+ * Return -ECANCELED if this is the smack access Smack attribute.
*/
- if (strcmp(name, XATTR_NAME_SMACK) == 0)
- return 1;
+ if (!strcmp(name, XATTR_NAME_SMACK))
+ return -ECANCELED;

return -EOPNOTSUPP;
}
--
2.30.2