blob: 38940a1c1373c786cc6ba7f31ba81d8c47211325 [file] [log] [blame]
/***********************************************************************
Net-SNMP - Simple Network Management Protocol agent library.
***********************************************************************/
/** @file kernel.c
* Net-SNMP Kernel Data Access Library.
* Provides access to kernel virtual memory for systems that
* support it.
* @author See README file for a list of contributors
*/
/* Copyrights:
* Copyright holders are listed in README file.
* Redistribution and use in source and binary forms, with or
* without modification, are permitted. License terms are specified
* in COPYING file distributed with the Net-SNMP package.
*/
/***********************************************************************/
#include <net-snmp/net-snmp-config.h>
#ifdef NETSNMP_CAN_USE_NLIST
#include <sys/types.h>
#if HAVE_STDLIB_H
#include <stdlib.h>
#endif
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <stdio.h>
#include <errno.h>
#if HAVE_STRING_H
#include <string.h>
#endif
#if HAVE_FCNTL_H
#include <fcntl.h>
#endif
#if HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#if HAVE_KVM_H
#include <kvm.h>
#endif
#include <net-snmp/net-snmp-includes.h>
#include "kernel.h"
#include <net-snmp/agent/ds_agent.h>
#ifndef NULL
#define NULL 0
#endif
#if HAVE_KVM_H
kvm_t *kd = NULL;
/**
* Initialize the support for accessing kernel virtual memory.
*
* @return TRUE upon success; FALSE upon failure.
*/
int
init_kmem(const char *file)
{
int res = TRUE;
#if HAVE_KVM_OPENFILES
char err[4096];
kd = kvm_openfiles(NULL, NULL, NULL, O_RDONLY, err);
if (!kd)
#ifdef KVM_NO_FILES
kd = kvm_openfiles(NULL, NULL, NULL, KVM_NO_FILES, err);
#else
kd = kvm_openfiles(NULL, "/dev/null", NULL, O_RDONLY, err);
#endif
if (!kd && !netsnmp_ds_get_boolean(NETSNMP_DS_APPLICATION_ID,
NETSNMP_DS_AGENT_NO_ROOT_ACCESS)) {
snmp_log(LOG_CRIT, "init_kmem: kvm_openfiles failed: %s\n", err);
res = FALSE;
}
#else
kd = kvm_open(NULL, NULL, NULL, O_RDONLY, NULL);
if (!kd && !netsnmp_ds_get_boolean(NETSNMP_DS_APPLICATION_ID,
NETSNMP_DS_AGENT_NO_ROOT_ACCESS)) {
snmp_log(LOG_CRIT, "init_kmem: kvm_open failed: %s\n",
strerror(errno));
res = FALSE;
}
#endif /* HAVE_KVM_OPENFILES */
return res;
}
/** Reads kernel memory.
* Seeks to the specified location in kmem, then
* does a read of given amount ob bytes into target buffer.
*
* @param off The location to seek.
*
* @param target The target buffer to read into.
*
* @param siz Number of bytes to read.
*
* @return gives 1 on success and 0 on failure.
*/
int
klookup(unsigned long off, void *target, size_t siz)
{
int result;
if (kd == NULL)
return 0;
result = kvm_read(kd, off, target, siz);
if (result != siz) {
#if HAVE_KVM_OPENFILES
snmp_log(LOG_ERR, "kvm_read(*, %lx, %p, %zx) = %d: %s\n", off,
target, siz, result, kvm_geterr(kd));
#else
snmp_log(LOG_ERR, "kvm_read(*, %lx, %p, %d) = %d: ", off, target,
siz, result);
snmp_log_perror("klookup");
#endif
return 0;
}
return 1;
}
/** Closes the kernel memory support.
*/
void
free_kmem(void)
{
if (kd != NULL)
{
kvm_close(kd);
kd = NULL;
}
}
#else /* HAVE_KVM_H */
static off_t klseek(off_t);
static int klread(char *, int);
int swap = -1, mem = -1, kmem = -1;
/**
* Initialize the support for accessing kernel virtual memory.
*
* @return TRUE upon success; FALSE upon failure.
*/
int
init_kmem(const char *file)
{
const int no_root_access = netsnmp_ds_get_boolean(NETSNMP_DS_APPLICATION_ID,
NETSNMP_DS_AGENT_NO_ROOT_ACCESS);
int res = TRUE;
kmem = open(file, O_RDONLY);
if (kmem < 0 && !no_root_access) {
snmp_log_perror(file);
res = FALSE;
}
if (kmem >= 0)
fcntl(kmem, F_SETFD, 1/*FD_CLOEXEC*/);
mem = open("/dev/mem", O_RDONLY);
if (mem < 0 && !no_root_access) {
snmp_log_perror("/dev/mem");
res = FALSE;
}
if (mem >= 0)
fcntl(mem, F_SETFD, 1/*FD_CLOEXEC*/);
#ifdef DMEM_LOC
swap = open(DMEM_LOC, O_RDONLY);
if (swap < 0 && !no_root_access) {
snmp_log_perror(DMEM_LOC);
res = FALSE;
}
if (swap >= 0)
fcntl(swap, F_SETFD, 1/*FD_CLOEXEC*/);
#endif
return res;
}
/** @private
* Seek into the kernel for a value.
*/
static off_t
klseek(off_t base)
{
return (lseek(kmem, (off_t) base, SEEK_SET));
}
/** @private
* Read from the kernel.
*/
static int
klread(char *buf, int buflen)
{
return (read(kmem, buf, buflen));
}
/** Reads kernel memory.
* Seeks to the specified location in kmem, then
* does a read of given amount ob bytes into target buffer.
*
* @param off The location to seek.
*
* @param target The target buffer to read into.
*
* @param siz Number of bytes to read.
*
* @return gives 1 on success and 0 on failure.
*/
int
klookup(unsigned long off, void *target, size_t siz)
{
long retsiz;
if (kmem < 0)
return 0;
if ((retsiz = klseek((off_t) off)) != off) {
snmp_log(LOG_ERR, "klookup(%lx, %p, %d): ", off, target, siz);
snmp_log_perror("klseek");
return (0);
}
if ((retsiz = klread(target, siz)) != siz) {
if (snmp_get_do_debugging()) {
/*
* these happen too often on too many architectures to print them
* unless we're in debugging mode. People get very full log files.
*/
snmp_log(LOG_ERR, "klookup(%lx, %p, %d): ", off, target, siz);
snmp_log_perror("klread");
}
return (0);
}
DEBUGMSGTL(("verbose:kernel:klookup", "klookup(%lx, %p, %d) succeeded", off, target, siz));
return (1);
}
/** Closes the kernel memory support.
*/
void
free_kmem(void)
{
if (swap >= 0) {
close(swap);
swap = -1;
}
if (mem >= 0) {
close(mem);
mem = -1;
}
if (kmem >= 0) {
close(kmem);
kmem = -1;
}
}
#endif /* HAVE_KVM_H */
#else
int unused; /* Suppress "empty translation unit" warning */
#endif /* NETSNMP_CAN_USE_NLIST */