[PATCH v3 2/6] security: Rewrite security_old_inode_init_security()
From: Roberto Sassu <roberto.sassu@huawei.com>
Date: 2021-04-27 11:37:55
Also in:
linux-fsdevel, linux-integrity, lkml, selinux
Subsystem:
security subsystem, the rest · Maintainers:
Paul Moore, James Morris, "Serge E. Hallyn", Linus Torvalds
With upcoming changes, LSMs will be able to write their xattrs in the reserved slots. Boundary checking will be performed to ensure that LSMs don't write outside the passed xattr array. However, the xattr array is created only in security_inode_init_security() and not in security_old_inode_init_security(). Instead of duplicating the code for array allocation, this patch calls security_inode_init_security() from security_old_inode_init_security() and introduces a new callback, called security_initxattrs(), to copy the first element of the xattr array allocated by former function into the destination pointer provided by the latter function. Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com> --- security/security.c | 41 ++++++++++++++++++++++++++++++++++++++--- 1 file changed, 38 insertions(+), 3 deletions(-)
diff --git a/security/security.c b/security/security.c
index 7f14e59c4f8e..692a148ce764 100644
--- a/security/security.c
+++ b/security/security.c@@ -1024,6 +1024,20 @@ int security_dentry_create_files_as(struct dentry *dentry, int mode, } EXPORT_SYMBOL(security_dentry_create_files_as); +static int security_initxattrs(struct inode *inode, const struct xattr *xattrs, + void *fs_info) +{ + struct xattr *dest = (struct xattr *)fs_info; + + if (!dest) + return 0; + + dest->name = xattrs->name; + dest->value = xattrs->value; + dest->value_len = xattrs->value_len; + return 0; +} + int security_inode_init_security(struct inode *inode, struct inode *dir, const struct qstr *qstr, const initxattrs initxattrs, void *fs_data)
@@ -1053,8 +1067,14 @@ int security_inode_init_security(struct inode *inode, struct inode *dir, goto out; ret = initxattrs(inode, new_xattrs, fs_data); out: - for (xattr = new_xattrs; xattr->value != NULL; xattr++) + for (xattr = new_xattrs; xattr->value != NULL; xattr++) { + if (xattr == new_xattrs && initxattrs == &security_initxattrs && + !ret && fs_data != NULL) + continue; kfree(xattr->value); + } + if (initxattrs == &security_initxattrs) + return ret; return (ret == -EOPNOTSUPP) ? 0 : ret; } EXPORT_SYMBOL(security_inode_init_security);
@@ -1071,10 +1091,25 @@ int security_old_inode_init_security(struct inode *inode, struct inode *dir, const struct qstr *qstr, const char **name, void **value, size_t *len) { + struct xattr xattr = { .name = NULL, .value = NULL, .value_len = 0 }; + struct xattr *lsm_xattr = (name && value && len) ? &xattr : NULL; + int ret; + if (unlikely(IS_PRIVATE(inode))) return -EOPNOTSUPP; - return call_int_hook(inode_init_security, -EOPNOTSUPP, inode, dir, - qstr, name, value, len); + + ret = security_inode_init_security(inode, dir, qstr, + security_initxattrs, lsm_xattr); + if (ret) + return ret; + + if (lsm_xattr) { + *name = lsm_xattr->name; + *value = lsm_xattr->value; + *len = lsm_xattr->value_len; + } + + return 0; } EXPORT_SYMBOL(security_old_inode_init_security);
--
2.25.1