netfilter: Remove checks of seq_printf() return values

[mirror_ubuntu-bionic-kernel.git] / net / netfilter / nf_log.c

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/skbuff.h>
#include <linux/netfilter.h>
#include <linux/seq_file.h>
#include <net/protocol.h>
#include <net/netfilter/nf_log.h>

#include "nf_internals.h"

/* Internal logging interface, which relies on the real
   LOG target modules */

#define NF_LOG_PREFIXLEN                128
#define NFLOGGER_NAME_LEN               64

static struct nf_logger __rcu *loggers[NFPROTO_NUMPROTO][NF_LOG_TYPE_MAX] __read_mostly;
static DEFINE_MUTEX(nf_log_mutex);

static struct nf_logger *__find_logger(int pf, const char *str_logger)
{
        struct nf_logger *log;
        int i;

        for (i = 0; i < NF_LOG_TYPE_MAX; i++) {
                if (loggers[pf][i] == NULL)
                        continue;

                log = rcu_dereference_protected(loggers[pf][i],
                                                lockdep_is_held(&nf_log_mutex));
                if (!strncasecmp(str_logger, log->name, strlen(log->name)))
                        return log;
        }

        return NULL;
}

void nf_log_set(struct net *net, u_int8_t pf, const struct nf_logger *logger)
{
        const struct nf_logger *log;

        if (pf == NFPROTO_UNSPEC)
                return;

        mutex_lock(&nf_log_mutex);
        log = rcu_dereference_protected(net->nf.nf_loggers[pf],
                                        lockdep_is_held(&nf_log_mutex));
        if (log == NULL)
                rcu_assign_pointer(net->nf.nf_loggers[pf], logger);

        mutex_unlock(&nf_log_mutex);
}
EXPORT_SYMBOL(nf_log_set);

void nf_log_unset(struct net *net, const struct nf_logger *logger)
{
        int i;
        const struct nf_logger *log;

        mutex_lock(&nf_log_mutex);
        for (i = 0; i < NFPROTO_NUMPROTO; i++) {
                log = rcu_dereference_protected(net->nf.nf_loggers[i],
                                lockdep_is_held(&nf_log_mutex));
                if (log == logger)
                        RCU_INIT_POINTER(net->nf.nf_loggers[i], NULL);
        }
        mutex_unlock(&nf_log_mutex);
        synchronize_rcu();
}
EXPORT_SYMBOL(nf_log_unset);

/* return EEXIST if the same logger is registered, 0 on success. */
int nf_log_register(u_int8_t pf, struct nf_logger *logger)
{
        int i;

        if (pf >= ARRAY_SIZE(init_net.nf.nf_loggers))
                return -EINVAL;

        mutex_lock(&nf_log_mutex);

        if (pf == NFPROTO_UNSPEC) {
                for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++)
                        rcu_assign_pointer(loggers[i][logger->type], logger);
        } else {
                /* register at end of list to honor first register win */
                rcu_assign_pointer(loggers[pf][logger->type], logger);
        }

        mutex_unlock(&nf_log_mutex);

        return 0;
}
EXPORT_SYMBOL(nf_log_register);

void nf_log_unregister(struct nf_logger *logger)
{
        int i;

        mutex_lock(&nf_log_mutex);
        for (i = 0; i < NFPROTO_NUMPROTO; i++)
                RCU_INIT_POINTER(loggers[i][logger->type], NULL);
        mutex_unlock(&nf_log_mutex);
}
EXPORT_SYMBOL(nf_log_unregister);

int nf_log_bind_pf(struct net *net, u_int8_t pf,
                   const struct nf_logger *logger)
{
        if (pf >= ARRAY_SIZE(net->nf.nf_loggers))
                return -EINVAL;
        mutex_lock(&nf_log_mutex);
        if (__find_logger(pf, logger->name) == NULL) {
                mutex_unlock(&nf_log_mutex);
                return -ENOENT;
        }
        rcu_assign_pointer(net->nf.nf_loggers[pf], logger);
        mutex_unlock(&nf_log_mutex);
        return 0;
}
EXPORT_SYMBOL(nf_log_bind_pf);

void nf_log_unbind_pf(struct net *net, u_int8_t pf)
{
        if (pf >= ARRAY_SIZE(net->nf.nf_loggers))
                return;
        mutex_lock(&nf_log_mutex);
        RCU_INIT_POINTER(net->nf.nf_loggers[pf], NULL);
        mutex_unlock(&nf_log_mutex);
}
EXPORT_SYMBOL(nf_log_unbind_pf);

void nf_logger_request_module(int pf, enum nf_log_type type)
{
        if (loggers[pf][type] == NULL)
                request_module("nf-logger-%u-%u", pf, type);
}
EXPORT_SYMBOL_GPL(nf_logger_request_module);

int nf_logger_find_get(int pf, enum nf_log_type type)
{
        struct nf_logger *logger;
        int ret = -ENOENT;

        logger = loggers[pf][type];
        if (logger == NULL)
                request_module("nf-logger-%u-%u", pf, type);

        rcu_read_lock();
        logger = rcu_dereference(loggers[pf][type]);
        if (logger == NULL)
                goto out;

        if (logger && try_module_get(logger->me))
                ret = 0;
out:
        rcu_read_unlock();
        return ret;
}
EXPORT_SYMBOL_GPL(nf_logger_find_get);

void nf_logger_put(int pf, enum nf_log_type type)
{
        struct nf_logger *logger;

        BUG_ON(loggers[pf][type] == NULL);

        rcu_read_lock();
        logger = rcu_dereference(loggers[pf][type]);
        module_put(logger->me);
        rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(nf_logger_put);

void nf_log_packet(struct net *net,
                   u_int8_t pf,
                   unsigned int hooknum,
                   const struct sk_buff *skb,
                   const struct net_device *in,
                   const struct net_device *out,
                   const struct nf_loginfo *loginfo,
                   const char *fmt, ...)
{
        va_list args;
        char prefix[NF_LOG_PREFIXLEN];
        const struct nf_logger *logger;

        rcu_read_lock();
        if (loginfo != NULL)
                logger = rcu_dereference(loggers[pf][loginfo->type]);
        else
                logger = rcu_dereference(net->nf.nf_loggers[pf]);

        if (logger) {
                va_start(args, fmt);
                vsnprintf(prefix, sizeof(prefix), fmt, args);
                va_end(args);
                logger->logfn(net, pf, hooknum, skb, in, out, loginfo, prefix);
        }
        rcu_read_unlock();
}
EXPORT_SYMBOL(nf_log_packet);

#define S_SIZE (1024 - (sizeof(unsigned int) + 1))

struct nf_log_buf {
        unsigned int    count;
        char            buf[S_SIZE + 1];
};
static struct nf_log_buf emergency, *emergency_ptr = &emergency;

__printf(2, 3) int nf_log_buf_add(struct nf_log_buf *m, const char *f, ...)
{
        va_list args;
        int len;

        if (likely(m->count < S_SIZE)) {
                va_start(args, f);
                len = vsnprintf(m->buf + m->count, S_SIZE - m->count, f, args);
                va_end(args);
                if (likely(m->count + len < S_SIZE)) {
                        m->count += len;
                        return 0;
                }
        }
        m->count = S_SIZE;
        printk_once(KERN_ERR KBUILD_MODNAME " please increase S_SIZE\n");
        return -1;
}
EXPORT_SYMBOL_GPL(nf_log_buf_add);

struct nf_log_buf *nf_log_buf_open(void)
{
        struct nf_log_buf *m = kmalloc(sizeof(*m), GFP_ATOMIC);

        if (unlikely(!m)) {
                local_bh_disable();
                do {
                        m = xchg(&emergency_ptr, NULL);
                } while (!m);
        }
        m->count = 0;
        return m;
}
EXPORT_SYMBOL_GPL(nf_log_buf_open);

void nf_log_buf_close(struct nf_log_buf *m)
{
        m->buf[m->count] = 0;
        printk("%s\n", m->buf);

        if (likely(m != &emergency))
                kfree(m);
        else {
                emergency_ptr = m;
                local_bh_enable();
        }
}
EXPORT_SYMBOL_GPL(nf_log_buf_close);

#ifdef CONFIG_PROC_FS
static void *seq_start(struct seq_file *seq, loff_t *pos)
{
        struct net *net = seq_file_net(seq);

        mutex_lock(&nf_log_mutex);

        if (*pos >= ARRAY_SIZE(net->nf.nf_loggers))
                return NULL;

        return pos;
}

static void *seq_next(struct seq_file *s, void *v, loff_t *pos)
{
        struct net *net = seq_file_net(s);

        (*pos)++;

        if (*pos >= ARRAY_SIZE(net->nf.nf_loggers))
                return NULL;

        return pos;
}

static void seq_stop(struct seq_file *s, void *v)
{
        mutex_unlock(&nf_log_mutex);
}

static int seq_show(struct seq_file *s, void *v)
{
        loff_t *pos = v;
        const struct nf_logger *logger;
        int i;
        struct net *net = seq_file_net(s);

        logger = rcu_dereference_protected(net->nf.nf_loggers[*pos],
                                           lockdep_is_held(&nf_log_mutex));

        if (!logger)
                seq_printf(s, "%2lld NONE (", *pos);
        else
                seq_printf(s, "%2lld %s (", *pos, logger->name);

        if (seq_has_overflowed(s))
                return -ENOSPC;

        for (i = 0; i < NF_LOG_TYPE_MAX; i++) {
                if (loggers[*pos][i] == NULL)
                        continue;

                logger = rcu_dereference_protected(loggers[*pos][i],
                                           lockdep_is_held(&nf_log_mutex));
                seq_printf(s, "%s", logger->name);
                if (i == 0 && loggers[*pos][i + 1] != NULL)
                        seq_printf(s, ",");

                if (seq_has_overflowed(s))
                        return -ENOSPC;
        }

        seq_printf(s, ")\n");

        if (seq_has_overflowed(s))
                return -ENOSPC;
        return 0;
}

static const struct seq_operations nflog_seq_ops = {
        .start  = seq_start,
        .next   = seq_next,
        .stop   = seq_stop,
        .show   = seq_show,
};

static int nflog_open(struct inode *inode, struct file *file)
{
        return seq_open_net(inode, file, &nflog_seq_ops,
                            sizeof(struct seq_net_private));
}

static const struct file_operations nflog_file_ops = {
        .owner   = THIS_MODULE,
        .open    = nflog_open,
        .read    = seq_read,
        .llseek  = seq_lseek,
        .release = seq_release_net,
};


#endif /* PROC_FS */

#ifdef CONFIG_SYSCTL
static char nf_log_sysctl_fnames[NFPROTO_NUMPROTO-NFPROTO_UNSPEC][3];
static struct ctl_table nf_log_sysctl_table[NFPROTO_NUMPROTO+1];

static int nf_log_proc_dostring(struct ctl_table *table, int write,
                         void __user *buffer, size_t *lenp, loff_t *ppos)
{
        const struct nf_logger *logger;
        char buf[NFLOGGER_NAME_LEN];
        size_t size = *lenp;
        int r = 0;
        int tindex = (unsigned long)table->extra1;
        struct net *net = current->nsproxy->net_ns;

        if (write) {
                if (size > sizeof(buf))
                        size = sizeof(buf);
                if (copy_from_user(buf, buffer, size))
                        return -EFAULT;

                if (!strcmp(buf, "NONE")) {
                        nf_log_unbind_pf(net, tindex);
                        return 0;
                }
                mutex_lock(&nf_log_mutex);
                logger = __find_logger(tindex, buf);
                if (logger == NULL) {
                        mutex_unlock(&nf_log_mutex);
                        return -ENOENT;
                }
                rcu_assign_pointer(net->nf.nf_loggers[tindex], logger);
                mutex_unlock(&nf_log_mutex);
        } else {
                mutex_lock(&nf_log_mutex);
                logger = rcu_dereference_protected(net->nf.nf_loggers[tindex],
                                                   lockdep_is_held(&nf_log_mutex));
                if (!logger)
                        table->data = "NONE";
                else
                        table->data = logger->name;
                r = proc_dostring(table, write, buffer, lenp, ppos);
                mutex_unlock(&nf_log_mutex);
        }

        return r;
}

static int netfilter_log_sysctl_init(struct net *net)
{
        int i;
        struct ctl_table *table;

        table = nf_log_sysctl_table;
        if (!net_eq(net, &init_net)) {
                table = kmemdup(nf_log_sysctl_table,
                                 sizeof(nf_log_sysctl_table),
                                 GFP_KERNEL);
                if (!table)
                        goto err_alloc;
        } else {
                for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++) {
                        snprintf(nf_log_sysctl_fnames[i],
                                 3, "%d", i);
                        nf_log_sysctl_table[i].procname =
                                nf_log_sysctl_fnames[i];
                        nf_log_sysctl_table[i].data = NULL;
                        nf_log_sysctl_table[i].maxlen =
                                NFLOGGER_NAME_LEN * sizeof(char);
                        nf_log_sysctl_table[i].mode = 0644;
                        nf_log_sysctl_table[i].proc_handler =
                                nf_log_proc_dostring;
                        nf_log_sysctl_table[i].extra1 =
                                (void *)(unsigned long) i;
                }
        }

        net->nf.nf_log_dir_header = register_net_sysctl(net,
                                                "net/netfilter/nf_log",
                                                table);
        if (!net->nf.nf_log_dir_header)
                goto err_reg;

        return 0;

err_reg:
        if (!net_eq(net, &init_net))
                kfree(table);
err_alloc:
        return -ENOMEM;
}

static void netfilter_log_sysctl_exit(struct net *net)
{
        struct ctl_table *table;

        table = net->nf.nf_log_dir_header->ctl_table_arg;
        unregister_net_sysctl_table(net->nf.nf_log_dir_header);
        if (!net_eq(net, &init_net))
                kfree(table);
}
#else
static int netfilter_log_sysctl_init(struct net *net)
{
        return 0;
}

static void netfilter_log_sysctl_exit(struct net *net)
{
}
#endif /* CONFIG_SYSCTL */

static int __net_init nf_log_net_init(struct net *net)
{
        int ret = -ENOMEM;

#ifdef CONFIG_PROC_FS
        if (!proc_create("nf_log", S_IRUGO,
                         net->nf.proc_netfilter, &nflog_file_ops))
                return ret;
#endif
        ret = netfilter_log_sysctl_init(net);
        if (ret < 0)
                goto out_sysctl;

        return 0;

out_sysctl:
#ifdef CONFIG_PROC_FS
        remove_proc_entry("nf_log", net->nf.proc_netfilter);
#endif
        return ret;
}

static void __net_exit nf_log_net_exit(struct net *net)
{
        netfilter_log_sysctl_exit(net);
#ifdef CONFIG_PROC_FS
        remove_proc_entry("nf_log", net->nf.proc_netfilter);
#endif
}

static struct pernet_operations nf_log_net_ops = {
        .init = nf_log_net_init,
        .exit = nf_log_net_exit,
};

int __init netfilter_log_init(void)
{
        return register_pernet_subsys(&nf_log_net_ops);
}