[PATCH] Updated audit failure query functionality
Timothy R. Chavez
tinytim at us.ibm.com
Mon Jun 26 22:55:30 UTC 2006
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;
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