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Fix: fixing security issue with ngx_palloc in set_to_pam_env #32

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Fix: fixing security issue with ngx_palloc in set_to_pam_env #32

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2a11299
Fix: changed types for functions, added checks. Haven't tested yet
StepanGulyaev Jun 10, 2025
820788a
fix: ngx_palloc no NULL check fixed
StepanGulyaev Jun 10, 2025
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27 changes: 22 additions & 5 deletions ngx_http_auth_pam_module.c
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Original file line number Diff line number Diff line change
Expand Up @@ -237,16 +237,21 @@ ngx_http_auth_pam_handler(ngx_http_request_t *r)
/**
* create a key value pair from the given key and value string
*/
static void set_to_pam_env(pam_handle_t *pamh, ngx_http_request_t *r,
static ngx_int_t set_to_pam_env(pam_handle_t *pamh, ngx_http_request_t *r,
char *key, char *value)
{
if (key != NULL && value != NULL) {
size_t size = strlen(key) + strlen(value) + 1 * sizeof(char);
char *key_value_pair = ngx_palloc(r->pool, size);
if (key_value_pair == NULL) {
return NGX_ERROR;
}
sprintf(key_value_pair, "%s=%s", key, value);

pam_putenv(pamh, key_value_pair);
}

return NGX_OK;
}

/**
Expand All @@ -268,14 +273,21 @@ static char* ngx_strncpy_s(ngx_str_t source, ngx_pool_t *pool)
/**
* enrich pam environment with request parameters
*/
static void add_request_info_to_pam_env(pam_handle_t *pamh,
static ngx_int_t add_request_info_to_pam_env(pam_handle_t *pamh,
ngx_http_request_t *r)
{
char *request_info = ngx_strncpy_s(r->request_line, r->pool);
char *host_info = ngx_strncpy_s(r->headers_in.host->value, r->pool);

set_to_pam_env(pamh, r, "REQUEST", request_info);
set_to_pam_env(pamh, r, "HOST", host_info);
if (set_to_pam_env(pamh, r, "REQUEST", request_info) != NGX_OK){
return NGX_ERROR;
}

if (set_to_pam_env(pamh, r, "HOST", host_info) != NGX_OK){
return NGX_ERROR;
}

return NGX_OK;
}

static ngx_int_t
Expand Down Expand Up @@ -351,7 +363,12 @@ ngx_http_auth_pam_authenticate(ngx_http_request_t *r,
}

if (alcf->set_pam_env) {
add_request_info_to_pam_env(pamh, r);
if (add_request_info_to_pam_env(pamh, r) != NGX_OK){
ngx_log_error(NGX_LOG_CRIT, r->connection->log, 0,
"PAM: Could not add request info to pam env: %s",
pam_strerror(pamh, rc));
return NGX_HTTP_INTERNAL_SERVER_ERROR;
}
}

/* try to authenticate user, log error on failure */
Expand Down