audit: Report suspicious O_CREAT usage

This renames the very specific audit_log_link_denied() to
audit_log_path_denied() and adds the AUDIT_* type as an argument. This
allows for the creation of the new AUDIT_ANOM_CREAT that can be used to
report the fifo/regular file creation restrictions that were introduced
in commit 30aba6656f61 ("namei: allow restricted O_CREAT of FIFOs and
regular files").

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Paul Moore <paul@paul-moore.com>

diff --git a/fs/namei.c b/fs/namei.c
index 671c3c1a3425bab83d07a6b1091360dc7d03b9f0..2dda552bcf7a272d82e1bda48a49885110125db3 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -925,7 +925,7 @@ static inline int may_follow_link(struct nameidata *nd)
                return -ECHILD;
 
        audit_inode(nd->name, nd->stack[0].link.dentry, 0);
-       audit_log_link_denied("follow_link");
+       audit_log_path_denied(AUDIT_ANOM_LINK, "follow_link");
        return -EACCES;
 }
 
@@ -993,7 +993,7 @@ static int may_linkat(struct path *link)
        if (safe_hardlink_source(inode) || inode_owner_or_capable(inode))
                return 0;
 
-       audit_log_link_denied("linkat");
+       audit_log_path_denied(AUDIT_ANOM_LINK, "linkat");
        return -EPERM;
 }
 
@@ -1031,6 +1031,10 @@ static int may_create_in_sticky(struct dentry * const dir,
            (dir->d_inode->i_mode & 0020 &&
             ((sysctl_protected_fifos >= 2 && S_ISFIFO(inode->i_mode)) ||
              (sysctl_protected_regular >= 2 && S_ISREG(inode->i_mode))))) {
+               const char *operation = S_ISFIFO(inode->i_mode) ?
+                                       "sticky_create_fifo" :
+                                       "sticky_create_regular";
+               audit_log_path_denied(AUDIT_ANOM_CREAT, operation);
                return -EACCES;
        }
        return 0;

diff --git a/include/linux/audit.h b/include/linux/audit.h
index aee3dc9eb378ec3ec69ea428975375a0758c1fb4..f9ceae57ca8de53217741ba2236c94ddaec17d7e 100644 (file)
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -156,7 +156,8 @@ extern void             audit_log_d_path(struct audit_buffer *ab,
                                             const struct path *path);
 extern void                audit_log_key(struct audit_buffer *ab,
                                          char *key);
-extern void                audit_log_link_denied(const char *operation);
+extern void                audit_log_path_denied(int type,
+                                                 const char *operation);
 extern void                audit_log_lost(const char *message);
 
 extern int audit_log_task_context(struct audit_buffer *ab);
@@ -217,7 +218,7 @@ static inline void audit_log_d_path(struct audit_buffer *ab,
 { }
 static inline void audit_log_key(struct audit_buffer *ab, char *key)
 { }
-static inline void audit_log_link_denied(const char *string)
+static inline void audit_log_path_denied(int type, const char *operation)
 { }
 static inline int audit_log_task_context(struct audit_buffer *ab)
 {

diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h
index c89c6495983d5d9d0f861ea180b8257aca96a453..3ad935527177bc734e7a0fad7b7d2f198a001268 100644 (file)
--- a/include/uapi/linux/audit.h
+++ b/include/uapi/linux/audit.h
@@ -143,6 +143,7 @@
 #define AUDIT_ANOM_PROMISCUOUS      1700 /* Device changed promiscuous mode */
 #define AUDIT_ANOM_ABEND            1701 /* Process ended abnormally */
 #define AUDIT_ANOM_LINK                    1702 /* Suspicious use of file links */
+#define AUDIT_ANOM_CREAT           1703 /* Suspicious file creation */
 #define AUDIT_INTEGRITY_DATA       1800 /* Data integrity verification */
 #define AUDIT_INTEGRITY_METADATA    1801 /* Metadata integrity verification */
 #define AUDIT_INTEGRITY_STATUS     1802 /* Integrity enable status */

diff --git a/kernel/audit.c b/kernel/audit.c
index da8dc0db5bd3c0a9625827b597bb91bac01de914..d75485aa25ff3f3faa704852e03ff509a47e9e8a 100644 (file)
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -2155,18 +2155,19 @@ void audit_log_task_info(struct audit_buffer *ab)
 EXPORT_SYMBOL(audit_log_task_info);
 
 /**
- * audit_log_link_denied - report a link restriction denial
- * @operation: specific link operation
+ * audit_log_path_denied - report a path restriction denial
+ * @type: audit message type (AUDIT_ANOM_LINK, AUDIT_ANOM_CREAT, etc)
+ * @operation: specific operation name
  */
-void audit_log_link_denied(const char *operation)
+void audit_log_path_denied(int type, const char *operation)
 {
        struct audit_buffer *ab;
 
        if (!audit_enabled || audit_dummy_context())
                return;
 
-       /* Generate AUDIT_ANOM_LINK with subject, operation, outcome. */
-       ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_ANOM_LINK);
+       /* Generate log with subject, operation, outcome. */
+       ab = audit_log_start(audit_context(), GFP_KERNEL, type);
        if (!ab)
                return;
        audit_log_format(ab, "op=%s", operation);