[PATCH v2 5/7] ima: Define new template fields xattrnames, xattrlengths and xattrvalues
Roberto Sassu
roberto.sassu at huawei.com
Fri May 28 07:38:10 UTC 2021
This patch defines the new template fields xattrnames, xattrlengths and
xattrvalues, which contain respectively a list of xattr names (strings,
separated by |), lengths (u32, hex) and values (hex). If an xattr is not
present, the name and length are not displayed in the measurement list.
Signed-off-by: Roberto Sassu <roberto.sassu at huawei.com>
---
Documentation/security/IMA-templates.rst | 4 ++
include/linux/evm.h | 10 ++++
security/integrity/evm/evm_main.c | 69 +++++++++++++++++++++++
security/integrity/ima/ima_template.c | 9 +++
security/integrity/ima/ima_template_lib.c | 64 +++++++++++++++++++++
security/integrity/ima/ima_template_lib.h | 6 ++
6 files changed, 162 insertions(+)
diff --git a/Documentation/security/IMA-templates.rst b/Documentation/security/IMA-templates.rst
index 65c1ce451d08..6a58760a0a35 100644
--- a/Documentation/security/IMA-templates.rst
+++ b/Documentation/security/IMA-templates.rst
@@ -78,6 +78,10 @@ descriptors by adding their identifier to the format string
- 'iuid': the inode UID;
- 'igid': the inode GID;
- 'imode': the inode mode;
+ - 'xattrnames': a list of xattr names (separated by |), only if the xattr is
+ present;
+ - 'xattrlengths': a list of xattr lengths (u32), only if the xattr is present;
+ - 'xattrvalues': a list of xattr values;
Below, there is the list of defined template descriptors:
diff --git a/include/linux/evm.h b/include/linux/evm.h
index 5011a299c251..4c374be70247 100644
--- a/include/linux/evm.h
+++ b/include/linux/evm.h
@@ -39,6 +39,9 @@ extern int evm_inode_init_security(struct inode *inode,
struct xattr *evm);
extern bool evm_revalidate_status(const char *xattr_name);
extern int evm_protected_xattr_if_enabled(const char *req_xattr_name);
+extern int evm_read_protected_xattrs(struct dentry *dentry, u8 *buffer,
+ int buffer_size, char type,
+ bool canonical_fmt);
#ifdef CONFIG_FS_POSIX_ACL
extern int posix_xattr_acl(const char *xattrname);
#else
@@ -120,5 +123,12 @@ static inline int evm_protected_xattr_if_enabled(const char *req_xattr_name)
return false;
}
+static inline int evm_read_protected_xattrs(struct dentry *dentry, u8 *buffer,
+ int buffer_size, char type,
+ bool canonical_fmt)
+{
+ return -EOPNOTSUPP;
+}
+
#endif /* CONFIG_EVM */
#endif /* LINUX_EVM_H */
diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c
index ee4e17a790fb..2c226e634ae9 100644
--- a/security/integrity/evm/evm_main.c
+++ b/security/integrity/evm/evm_main.c
@@ -317,6 +317,75 @@ int evm_protected_xattr_if_enabled(const char *req_xattr_name)
return evm_protected_xattr_common(req_xattr_name, true);
}
+/**
+ * evm_read_protected_xattrs - read EVM protected xattr names, lengths, values
+ * @dentry: dentry of the read xattrs
+ * @inode: inode of the read xattrs
+ * @buffer: buffer xattr names, lengths or values are copied to
+ * @buffer_size: size of buffer
+ * @type: n: names, l: lengths, v: values
+ * @canonical_fmt: data format (true: little endian, false: native format)
+ *
+ * Read protected xattr names (separated by |), lengths (u32) or values for a
+ * given dentry and return the total size of copied data. If buffer is NULL,
+ * just return the total size.
+ *
+ * Returns the total size on success, a negative value on error.
+ */
+int evm_read_protected_xattrs(struct dentry *dentry, u8 *buffer,
+ int buffer_size, char type, bool canonical_fmt)
+{
+ struct xattr_list *xattr;
+ int rc, size, total_size = 0;
+
+ list_for_each_entry_lockless(xattr, &evm_config_xattrnames, list) {
+ rc = __vfs_getxattr(dentry, d_backing_inode(dentry),
+ xattr->name, NULL, 0);
+ if (rc < 0 && rc == -ENODATA)
+ continue;
+ else if (rc < 0)
+ return rc;
+
+ switch (type) {
+ case 'n':
+ size = strlen(xattr->name) + 1;
+ if (buffer) {
+ if (total_size)
+ *(buffer + total_size - 1) = '|';
+
+ memcpy(buffer + total_size, xattr->name, size);
+ }
+ break;
+ case 'l':
+ size = sizeof(u32);
+ if (buffer) {
+ if (canonical_fmt)
+ rc = cpu_to_le32(rc);
+
+ *(u32 *)(buffer + total_size) = rc;
+ }
+ break;
+ case 'v':
+ size = rc;
+ if (buffer) {
+ rc = __vfs_getxattr(dentry,
+ d_backing_inode(dentry), xattr->name,
+ buffer + total_size,
+ buffer_size - total_size);
+ if (rc < 0)
+ return rc;
+ }
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ total_size += size;
+ }
+
+ return total_size;
+}
+
/**
* evm_verifyxattr - verify the integrity of the requested xattr
* @dentry: object of the verify xattr
diff --git a/security/integrity/ima/ima_template.c b/security/integrity/ima/ima_template.c
index 43784f2bf8bd..159a31d2fcdf 100644
--- a/security/integrity/ima/ima_template.c
+++ b/security/integrity/ima/ima_template.c
@@ -53,6 +53,15 @@ static const struct ima_template_field supported_fields[] = {
.field_show = ima_show_template_uint},
{.field_id = "imode", .field_init = ima_eventinodemode_init,
.field_show = ima_show_template_uint},
+ {.field_id = "xattrnames",
+ .field_init = ima_eventinodexattrnames_init,
+ .field_show = ima_show_template_string},
+ {.field_id = "xattrlengths",
+ .field_init = ima_eventinodexattrlengths_init,
+ .field_show = ima_show_template_sig},
+ {.field_id = "xattrvalues",
+ .field_init = ima_eventinodexattrvalues_init,
+ .field_show = ima_show_template_sig},
};
/*
diff --git a/security/integrity/ima/ima_template_lib.c b/security/integrity/ima/ima_template_lib.c
index 3156fb34b1af..10a1349542e6 100644
--- a/security/integrity/ima/ima_template_lib.c
+++ b/security/integrity/ima/ima_template_lib.c
@@ -11,6 +11,7 @@
#include "ima_template_lib.h"
#include <linux/xattr.h>
+#include <linux/evm.h>
static bool ima_template_hash_algo_allowed(u8 algo)
{
@@ -618,3 +619,66 @@ int ima_eventinodemode_init(struct ima_event_data *event_data,
return ima_write_template_field_data((char *)&mode, sizeof(mode),
DATA_FMT_UINT, field_data);
}
+
+int ima_eventinodexattrs_init_common(struct ima_event_data *event_data,
+ struct ima_field_data *field_data,
+ char type)
+{
+ u8 *buffer = NULL;
+ int rc;
+
+ if (!event_data->file)
+ return 0;
+
+ rc = evm_read_protected_xattrs(file_dentry(event_data->file), NULL, 0,
+ type, ima_canonical_fmt);
+ if (rc < 0)
+ return 0;
+
+ buffer = kmalloc(rc, GFP_KERNEL);
+ if (!buffer)
+ return 0;
+
+ rc = evm_read_protected_xattrs(file_dentry(event_data->file), buffer,
+ rc, type, ima_canonical_fmt);
+ if (rc < 0) {
+ rc = 0;
+ goto out;
+ }
+
+ rc = ima_write_template_field_data((char *)buffer, rc, DATA_FMT_HEX,
+ field_data);
+out:
+ kfree(buffer);
+ return rc;
+}
+
+/*
+ * ima_eventinodexattrnames_init - include a list of xattr names as part of the
+ * template data
+ */
+int ima_eventinodexattrnames_init(struct ima_event_data *event_data,
+ struct ima_field_data *field_data)
+{
+ return ima_eventinodexattrs_init_common(event_data, field_data, 'n');
+}
+
+/*
+ * ima_eventinodexattrlengths_init - include a list of xattr lengths as part of
+ * the template data
+ */
+int ima_eventinodexattrlengths_init(struct ima_event_data *event_data,
+ struct ima_field_data *field_data)
+{
+ return ima_eventinodexattrs_init_common(event_data, field_data, 'l');
+}
+
+/*
+ * ima_eventinodexattrvalues_init - include a list of xattr values as part of
+ * the template data
+ */
+int ima_eventinodexattrvalues_init(struct ima_event_data *event_data,
+ struct ima_field_data *field_data)
+{
+ return ima_eventinodexattrs_init_common(event_data, field_data, 'v');
+}
diff --git a/security/integrity/ima/ima_template_lib.h b/security/integrity/ima/ima_template_lib.h
index 6509af4a97ee..c71f1de95753 100644
--- a/security/integrity/ima/ima_template_lib.h
+++ b/security/integrity/ima/ima_template_lib.h
@@ -56,4 +56,10 @@ int ima_eventinodegid_init(struct ima_event_data *event_data,
struct ima_field_data *field_data);
int ima_eventinodemode_init(struct ima_event_data *event_data,
struct ima_field_data *field_data);
+int ima_eventinodexattrnames_init(struct ima_event_data *event_data,
+ struct ima_field_data *field_data);
+int ima_eventinodexattrlengths_init(struct ima_event_data *event_data,
+ struct ima_field_data *field_data);
+int ima_eventinodexattrvalues_init(struct ima_event_data *event_data,
+ struct ima_field_data *field_data);
#endif /* __LINUX_IMA_TEMPLATE_LIB_H */
--
2.25.1
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