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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 30aba6656f ("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>
This commit is contained in:
Kees Cook 2019-10-02 16:41:58 -07:00 committed by Paul Moore
parent 54ecb8f702
commit 245d73698e
4 changed files with 16 additions and 9 deletions
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8
fs/namei.c
View File

@ -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;

5
include/linux/audit.h
View File

@ -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)
{

1
include/uapi/linux/audit.h
View File

@ -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 */

11
kernel/audit.c
View File

@ -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);