5:55 p.m.
On Mon, 2006-06-26 at 15:23 -0400, Lisa Smith wrote:
This is an updated patch for the audit failure query
functionality. The patch has been completely rewritten
to match the programming style and algorithms used in
auditd-config.c.
<snip>
Lisa
Hi Lisa,
I had some comments below. Thanks!
-tim
-------------------
libaudit.c | 246 +++++++++++++++++++++++++++++++++++++++++++++++++++++
libaudit.h | 11 ++
2 files changed, 257 insertions(+)
diff -burN orig/libaudit.c src/libaudit.c
--- orig/libaudit.c 2006-05-25 17:39:52.000000000 -0400
+++ src/libaudit.c 2006-06-26 15:00:56.000000000 -0400
@@ -42,13 +42,56 @@
#include "libaudit.h"
#include "private.h"
+/* Local prototypes */
+struct nv_pair
+{
+ const char *name;
+ const char *value;
+};
+
+struct kw_pair
+{
+ const char *name;
+ int (*parser)(const char *, int);
+};
+
+struct nv_list
+{
+ const char *name;
+ int option;
+};
+
+struct libaudit_conf
+{
+ auditfail_t failure_action;
+};
int audit_archadded = 0;
int audit_syscalladded = 0;
unsigned int audit_elf = 0U;
+static struct libaudit_conf config;
+static int load_libaudit_config();
+static char *get_line(FILE *f, char *buf);
+static int nv_split(char *buf, struct nv_pair *nv);
+static const struct kw_pair *kw_lookup(const char *val);
+static int audit_failure_parser(const char *val, int line);
static int name_to_uid(const char *name, uid_t *uid);
static int name_to_gid(const char *name, gid_t *gid);
+static const struct kw_pair keywords[] =
+{
+ {"failure_action", audit_failure_parser },
+ { NULL, NULL }
+};
+
+static const struct nv_list failure_actions[] =
+{
+ {"ignore", FA_IGNORE },
+ {"log", FA_LOG },
+ {"terminate", FA_TERMINATE },
+ { NULL, 0 }
+};
+
int audit_request_status(int fd)
{
@@ -68,6 +111,209 @@
return rc;
}
+/*
+ * Set everything to its default value
+*/
+static void clear_config()
+{
+ config.failure_action = FA_IGNORE;
+}
+
+static int load_libaudit_config()
+{
+ int fd, rc, lineno = 1;
+ struct stat st;
+ FILE *f;
+ char buf[128];
+
+ clear_config();
+
+ /* open the file */
+ rc = open(CONFIG_FILE, O_NOFOLLOW|O_RDONLY);
+ if (rc < 0) {
+ if (errno != ENOENT) {
+ audit_msg(LOG_ERR, "Error opening config file (%s)",
+ strerror(errno));
+ return 1;
+ }
+ audit_msg(LOG_WARNING,
+ "Config file %s doesn't exist, skipping",
CONFIG_FILE);
+ return 0;
+ }
+ fd = rc;
+
+ /* check the file's permissions: owned by root, not world writable,
+ * not symlink.
+ */
+ audit_msg(LOG_DEBUG, "Config file %s opened for parsing",
+ CONFIG_FILE);
+ if (fstat(fd, &st) < 0) {
+ audit_msg(LOG_ERR, "Error fstat'ing config file (%s)",
+ strerror(errno));
+ return 1;
+ }
+ if (st.st_uid != 0) {
+ audit_msg(LOG_ERR, "Error - %s isn't owned by root",
+ CONFIG_FILE);
+ return 1;
+ }
Hm, you really want to hard-code in a root check? What if you're acting
as another type of administrator with access to audit? Done know, I
could be out of line here.
[..]
+ if ((st.st_mode & S_IWOTH) == S_IWOTH) {
+ audit_msg(LOG_ERR, "Error - %s is world writable",
+ CONFIG_FILE);
+ return 1;
+ }
+ if (!S_ISREG(st.st_mode)) {
+ audit_msg(LOG_ERR, "Error - %s is not a regular file",
+ CONFIG_FILE);
+ return 1;
+ }
+
+ /* it's ok, read line by line */
+ f = fdopen(fd, "r");
+ if (f == NULL) {
+ audit_msg(LOG_ERR, "Error - fdopen failed (%s)",
+ strerror(errno));
+ return 1;
+ }
+
+ while (get_line(f, buf)) {
+ // convert line into name-value pair
+ const struct kw_pair *kw;
+ struct nv_pair nv;
+ rc = nv_split(buf, &nv);
+ switch (rc) {
+ case 0: // fine
+ break;
+ case 1: // not the right number of tokens.
+ audit_msg(LOG_ERR,
+ "Wrong number of arguments for line %d in
%s",
+ lineno, CONFIG_FILE);
+ break;
+ case 2: // no '=' sign
+ audit_msg(LOG_ERR,
+ "Missing equal sign for line %d in
%s",
+ lineno, CONFIG_FILE);
+ break;
+ default: // something else went wrong...
+ audit_msg(LOG_ERR,
+ "Unknown error for line %d in %s",
+ lineno, CONFIG_FILE);
+ break;
+ }
+ if (nv.name == NULL) {
+ lineno++;
+ continue;
+ }
+
+ /* identify keyword or error */
+ kw = kw_lookup(nv.name);
+ if (kw->name == NULL) {
+ audit_msg(LOG_ERR,
+ "Unknown keyword \"%s\" in line %d of
%s",
+ nv.name, lineno, CONFIG_FILE);
+ fclose(f);
+ return 1;
+ }
+
+ /* dispatch to keyword's local parser */
+ rc = kw->parser(nv.value, lineno);
+ if (rc != 0) {
+ fclose(f);
+ return 1; // local parser puts message out
+ }
+
+ lineno++;
+ }
+
+ fclose(f);
+ return 0;
+}
+
+int get_auditfail_action(auditfail_t *failmode)
+{
+ if (load_libaudit_config())
+ *failmode = config.failure_action;
+ return 1;
Missing brackets?
[..]
+
+ *failmode = config.failure_action;
+ return 0;
+}
+
+
+static char *get_line(FILE *f, char *buf)
+{
+ if (fgets_unlocked(buf, 128, f)) {
+ /* remove newline */
+ char *ptr = strchr(buf, 0x0a);
+ if (ptr)
+ *ptr = 0;
+ return buf;
+ }
+ return NULL;
+}
+
+static int nv_split(char *buf, struct nv_pair *nv)
+{
+ /* Get the name part */
+ char *ptr;
+
+ nv->name = NULL;
+ nv->value = NULL;
+ ptr = strtok(buf, " ");
+ if (ptr == NULL)
+ return 0; /* If there's nothing, go to next line */
+ if (ptr[0] == '#')
+ return 0; /* If there's a comment, go to next line */
I still think this will break if ptr[0] happens to be a space followed
by a '#'. I suppose it could break by design if the first character of
the line is not '#', but I wouldn't like that much as a user myself.
[..]
+ nv->name = ptr;
+
+ /* Check for a '=' */
+ ptr = strtok(NULL, " ");
+ if (ptr == NULL)
+ return 1;
+ if (strcmp(ptr, "=") != 0)
No real need to do a strcmp here.
if (ptr && *ptr == '=')
[..]
+ return 2;
+
+ /* get the value */
+ ptr = strtok(NULL, " ");
+ if (ptr == NULL)
+ return 1;
+ nv->value = ptr;
I'll be the first to admit that I relatively little experience with
strtok, but is this pointer assignment even safe? You're pointing into
a buffer that could potentially be overwritten by another app, right?
Here's my off-the-top-of-the-head, uncompiled, and untested example
using strtok_r...
char *buf;
char *ptr;
buf = (char *)malloc(128);
if (!buf) {
/* handle memory error */
}
ptr = strtok_r(line, "=", buf);
if (!ptr || *buf == '\0') {
/* not "token=value", free memory */
}
/* <do comment check here> */
nv->name = (char*)malloc(strlen(ptr)+1);
if (!nv->name) {
/* handle memory error */
}
strcpy(nv->name, ptr);
nv->value = (char*)malloc(strlen(buf)+1);
if (!nv->value) {
/* handle memory error */
}
strcpy(nv->value, buf);
/* clean up memory */
return 0;
You may not care about whether or not you're thread-safe or being able
to have multiple word token values... but at least by providing your own
buffer, you can keep track of your position in the parsed string in a
lovely way.
[..]
+
+ /* Make sure there's nothing else */
+ ptr = strtok(NULL, " ");
+ if (ptr)
+ return 1;
+
+ /* Everything is OK */
+ return 0;
+}
+
+static const struct kw_pair *kw_lookup(const char *val)
+{
+ int i = 0;
+ while (keywords[i].name != NULL) {
+ if (strcasecmp(keywords[i].name, val) == 0)
+ break;
+ i++;
+ }
+ return &keywords[i];
So I think this would look better a for-loop as you're in fact iterating
anyway :) *oh my, looks down at next function*
[..]
+}
+
+static int audit_failure_parser(const char *val, int line)
+{
+ int i;
+
+ audit_msg(LOG_DEBUG, "audit_failure_parser called with: %s", val);
+ for (i=0; failure_actions[i].name != NULL; i++) {
+ if (strcasecmp(val, failure_actions[i].name) == 0) {
+ config.failure_action = failure_actions[i].option;
+ return 0;
+ }
+ }
:)
[..]
+ audit_msg(LOG_ERR, "Option %s not found - line
%d", val, line);
+ return 1;
+}
+
int audit_set_enabled(int fd, uint32_t enabled)
{
int rc;
diff -burN orig/libaudit.h src/libaudit.h
--- orig/libaudit.h 2006-05-25 17:38:21.000000000 -0400
+++ src/libaudit.h 2006-06-26 14:58:53.000000000 -0400
@@ -248,6 +248,16 @@
MACH_ALPHA
} machine_t;
+/* These are the valid audit failure tunable enum values */
+typedef enum {
+ FA_IGNORE=0,
+ FA_LOG,
+ FA_TERMINATE
+} auditfail_t;
+
+/* #defines for the audit failure query */
+#define CONFIG_FILE "/etc/libaudit.conf"
+
/*
* audit_rule_data supports filter rules with both integer and string
* fields. It corresponds with AUDIT_ADD_RULE, AUDIT_DEL_RULE and
@@ -362,6 +372,7 @@
/* AUDIT_GET */
extern int audit_request_status(int fd);
extern int audit_is_enabled(int fd);
+extern int get_auditfail_action(auditfail_t *failmode);
/* AUDIT_SET */
typedef enum { WAIT_NO, WAIT_YES } rep_wait_t;