cregit-Linux how code gets into the kernel

Release 4.8 net/netfilter/nf_conntrack_ftp.c

Directory: net/netfilter
/* FTP extension for connection tracking. */

/* (C) 1999-2001 Paul `Rusty' Russell
 * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
 * (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
 * (C) 2006-2012 Patrick McHardy <kaber@trash.net>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */


#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/netfilter.h>
#include <linux/ip.h>
#include <linux/slab.h>
#include <linux/ipv6.h>
#include <linux/ctype.h>
#include <linux/inet.h>
#include <net/checksum.h>
#include <net/tcp.h>

#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_expect.h>
#include <net/netfilter/nf_conntrack_ecache.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <linux/netfilter/nf_conntrack_ftp.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>");
MODULE_DESCRIPTION("ftp connection tracking helper");
MODULE_ALIAS("ip_conntrack_ftp");
MODULE_ALIAS_NFCT_HELPER("ftp");

/* This is slow, but it's simple. --RR */

static char *ftp_buffer;

static DEFINE_SPINLOCK(nf_ftp_lock);


#define MAX_PORTS 8

static u_int16_t ports[MAX_PORTS];

static unsigned int ports_c;
module_param_array(ports, ushort, &ports_c, 0400);


static bool loose;
module_param(loose, bool, 0600);


unsigned int (*nf_nat_ftp_hook)(struct sk_buff *skb,
				enum ip_conntrack_info ctinfo,
				enum nf_ct_ftp_type type,
				unsigned int protoff,
				unsigned int matchoff,
				unsigned int matchlen,
				struct nf_conntrack_expect *exp);

EXPORT_SYMBOL_GPL(nf_nat_ftp_hook);

static int try_rfc959(const char *, size_t, struct nf_conntrack_man *,
		      char, unsigned int *);
static int try_rfc1123(const char *, size_t, struct nf_conntrack_man *,
		       char, unsigned int *);
static int try_eprt(const char *, size_t, struct nf_conntrack_man *,
		    char, unsigned int *);
static int try_epsv_response(const char *, size_t, struct nf_conntrack_man *,
			     char, unsigned int *);


static struct ftp_search {
	
const char *pattern;
	
size_t plen;
	
char skip;
	
char term;
	
enum nf_ct_ftp_type ftptype;
	
int (*getnum)(const char *, size_t, struct nf_conntrack_man *, char, unsigned int *);
} 
search[IP_CT_DIR_MAX][2] = {
	[IP_CT_DIR_ORIGINAL] = {
		{
			.pattern	= "PORT",
			.plen		= sizeof("PORT") - 1,
			.skip		= ' ',
			.term		= '\r',
			.ftptype	= NF_CT_FTP_PORT,
			.getnum		= try_rfc959,
                },
		{
			.pattern	= "EPRT",
			.plen		= sizeof("EPRT") - 1,
			.skip		= ' ',
			.term		= '\r',
			.ftptype	= NF_CT_FTP_EPRT,
			.getnum		= try_eprt,
                },
        },
	[IP_CT_DIR_REPLY] = {
		{
			.pattern	= "227 ",
			.plen		= sizeof("227 ") - 1,
			.ftptype	= NF_CT_FTP_PASV,
			.getnum		= try_rfc1123,
                },
		{
			.pattern	= "229 ",
			.plen		= sizeof("229 ") - 1,
			.skip		= '(',
			.term		= ')',
			.ftptype	= NF_CT_FTP_EPSV,
			.getnum		= try_epsv_response,
                },
        },
};


static int get_ipv6_addr(const char *src, size_t dlen, struct in6_addr *dst, u_int8_t term) { const char *end; int ret = in6_pton(src, min_t(size_t, dlen, 0xffff), (u8 *)dst, term, &end); if (ret > 0) return (int)(end - src); return 0; }

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yasuyuki kozakaiyasuyuki kozakai4763.51%133.33%
hideaki yoshifujihideaki yoshifuji1824.32%133.33%
david s. millerdavid s. miller912.16%133.33%
Total74100.00%3100.00%


static int try_number(const char *data, size_t dlen, u_int32_t array[], int array_size, char sep, char term) { u_int32_t i, len; memset(array, 0, sizeof(array[0])*array_size); /* Keep data pointing at next char. */ for (i = 0, len = 0; len < dlen && i < array_size; len++, data++) { if (*data >= '0' && *data <= '9') { array[i] = array[i]*10 + *data - '0'; } else if (*data == sep) i++; else { /* Unexpected character; true if it's the terminator (or we don't care about one) and we're finished. */ if ((*data == term || !term) && i == array_size - 1) return len; pr_debug("Char %u (got %u nums) `%u' unexpected\n", len, i, *data); return 0; } } pr_debug("Failed to fill %u numbers separated by %c\n", array_size, sep); return 0; }

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yasuyuki kozakaiyasuyuki kozakai16295.29%133.33%
jeff mahoneyjeff mahoney63.53%133.33%
patrick mchardypatrick mchardy21.18%133.33%
Total170100.00%3100.00%

/* Returns 0, or length of numbers: 192,168,1,1,5,6 */
static int try_rfc959(const char *data, size_t dlen, struct nf_conntrack_man *cmd, char term, unsigned int *offset) { int length; u_int32_t array[6]; length = try_number(data, dlen, array, 6, ',', term); if (length == 0) return 0; cmd->u3.ip = htonl((array[0] << 24) | (array[1] << 16) | (array[2] << 8) | array[3]); cmd->u.tcp.port = htons((array[4] << 8) | array[5]); return length; }

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yasuyuki kozakaiyasuyuki kozakai12696.18%150.00%
jeff mahoneyjeff mahoney53.82%150.00%
Total131100.00%2100.00%

/* * From RFC 1123: * The format of the 227 reply to a PASV command is not * well standardized. In particular, an FTP client cannot * assume that the parentheses shown on page 40 of RFC-959 * will be present (and in fact, Figure 3 on page 43 omits * them). Therefore, a User-FTP program that interprets * the PASV reply must scan the reply for the first digit * of the host and port numbers. */
static int try_rfc1123(const char *data, size_t dlen, struct nf_conntrack_man *cmd, char term, unsigned int *offset) { int i; for (i = 0; i < dlen; i++) if (isdigit(data[i])) break; if (i == dlen) return 0; *offset += i; return try_rfc959(data + i, dlen - i, cmd, 0, offset); }

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jeff mahoneyjeff mahoney86100.00%1100.00%
Total86100.00%1100.00%

/* Grab port: number up to delimiter */
static int get_port(const char *data, int start, size_t dlen, char delim, __be16 *port) { u_int16_t tmp_port = 0; int i; for (i = start; i < dlen; i++) { /* Finished? */ if (data[i] == delim) { if (tmp_port == 0) break; *port = htons(tmp_port); pr_debug("get_port: return %d\n", tmp_port); return i + 1; } else if (data[i] >= '0' && data[i] <= '9') tmp_port = tmp_port*10 + data[i] - '0'; else { /* Some other crap */ pr_debug("get_port: invalid char.\n"); break; } } return 0; }

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yasuyuki kozakaiyasuyuki kozakai12697.67%133.33%
patrick mchardypatrick mchardy32.33%266.67%
Total129100.00%3100.00%

/* Returns 0, or length of numbers: |1|132.235.1.2|6275| or |2|3ffe::1|6275| */
static int try_eprt(const char *data, size_t dlen, struct nf_conntrack_man *cmd, char term, unsigned int *offset) { char delim; int length; /* First character is delimiter, then "1" for IPv4 or "2" for IPv6, then delimiter again. */ if (dlen <= 3) { pr_debug("EPRT: too short\n"); return 0; } delim = data[0]; if (isdigit(delim) || delim < 33 || delim > 126 || data[2] != delim) { pr_debug("try_eprt: invalid delimitter.\n"); return 0; } if ((cmd->l3num == PF_INET && data[1] != '1') || (cmd->l3num == PF_INET6 && data[1] != '2')) { pr_debug("EPRT: invalid protocol number.\n"); return 0; } pr_debug("EPRT: Got %c%c%c\n", delim, data[1], delim); if (data[1] == '1') { u_int32_t array[4]; /* Now we have IP address. */ length = try_number(data + 3, dlen - 3, array, 4, '.', delim); if (length != 0) cmd->u3.ip = htonl((array[0] << 24) | (array[1] << 16) | (array[2] << 8) | array[3]); } else { /* Now we have IPv6 address. */ length = get_ipv6_addr(data + 3, dlen - 3, (struct in6_addr *)cmd->u3.ip6, delim); } if (length == 0) return 0; pr_debug("EPRT: Got IP address!\n"); /* Start offset includes initial "|1|", and trailing delimiter */ return get_port(data, 3 + length + 1, dlen, delim, &cmd->u.tcp.port); }

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yasuyuki kozakaiyasuyuki kozakai29196.68%133.33%
patrick mchardypatrick mchardy51.66%133.33%
jeff mahoneyjeff mahoney51.66%133.33%
Total301100.00%3100.00%

/* Returns 0, or length of numbers: |||6446| */
static int try_epsv_response(const char *data, size_t dlen, struct nf_conntrack_man *cmd, char term, unsigned int *offset) { char delim; /* Three delimiters. */ if (dlen <= 3) return 0; delim = data[0]; if (isdigit(delim) || delim < 33 || delim > 126 || data[1] != delim || data[2] != delim) return 0; return get_port(data, 3, dlen, delim, &cmd->u.tcp.port); }

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yasuyuki kozakaiyasuyuki kozakai9595.00%150.00%
jeff mahoneyjeff mahoney55.00%150.00%
Total100100.00%2100.00%

/* Return 1 for match, 0 for accept, -1 for partial. */
static int find_pattern(const char *data, size_t dlen, const char *pattern, size_t plen, char skip, char term, unsigned int *numoff, unsigned int *numlen, struct nf_conntrack_man *cmd, int (*getnum)(const char *, size_t, struct nf_conntrack_man *, char, unsigned int *)) { size_t i = plen; pr_debug("find_pattern `%s': dlen = %Zu\n", pattern, dlen); if (dlen == 0) return 0; if (dlen <= plen) { /* Short packet: try for partial? */ if (strncasecmp(data, pattern, dlen) == 0) return -1; else return 0; } if (strncasecmp(data, pattern, plen) != 0) { #if 0 size_t i; pr_debug("ftp: string mismatch\n"); for (i = 0; i < plen; i++) { pr_debug("ftp:char %u `%c'(%u) vs `%c'(%u)\n", i, data[i], data[i], pattern[i], pattern[i]); } #endif return 0; } pr_debug("Pattern matches!\n"); /* Now we've found the constant string, try to skip to the 'skip' character */ if (skip) { for (i = plen; data[i] != skip; i++) if (i == dlen - 1) return -1; /* Skip over the last character */ i++; } pr_debug("Skipped up to `%c'!\n", skip); *numoff = i; *numlen = getnum(data + i, dlen - i, cmd, term, numoff); if (!*numlen) return -1; pr_debug("Match succeeded!\n"); return 1; }

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yasuyuki kozakaiyasuyuki kozakai21590.72%125.00%
jeff mahoneyjeff mahoney145.91%125.00%
patrick mchardypatrick mchardy62.53%125.00%
rasmus villemoesrasmus villemoes20.84%125.00%
Total237100.00%4100.00%

/* Look up to see if we're just after a \n. */
static int find_nl_seq(u32 seq, const struct nf_ct_ftp_master *info, int dir) { unsigned int i; for (i = 0; i < info->seq_aft_nl_num[dir]; i++) if (info->seq_aft_nl[dir][i] == seq) return 1; return 0; }

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PersonTokensPropCommitsCommitProp
yasuyuki kozakaiyasuyuki kozakai5998.33%150.00%
jozsef kadlecsikjozsef kadlecsik11.67%150.00%
Total60100.00%2100.00%

/* We don't update if it's older than what we have. */
static void update_nl_seq(struct nf_conn *ct, u32 nl_seq, struct nf_ct_ftp_master *info, int dir, struct sk_buff *skb) { unsigned int i, oldest; /* Look for oldest: if we find exact match, we're done. */ for (i = 0; i < info->seq_aft_nl_num[dir]; i++) { if (info->seq_aft_nl[dir][i] == nl_seq) return; } if (info->seq_aft_nl_num[dir] < NUM_SEQ_TO_REMEMBER) { info->seq_aft_nl[dir][info->seq_aft_nl_num[dir]++] = nl_seq; } else { if (before(info->seq_aft_nl[dir][0], info->seq_aft_nl[dir][1])) oldest = 0; else oldest = 1; if (after(nl_seq, info->seq_aft_nl[dir][oldest])) info->seq_aft_nl[dir][oldest] = nl_seq; } }

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yasuyuki kozakaiyasuyuki kozakai11368.07%120.00%
patrick mchardypatrick mchardy4728.31%240.00%
alexey dobriyanalexey dobriyan53.01%120.00%
jozsef kadlecsikjozsef kadlecsik10.60%120.00%
Total166100.00%5100.00%


static int help(struct sk_buff *skb, unsigned int protoff, struct nf_conn *ct, enum ip_conntrack_info ctinfo) { unsigned int dataoff, datalen; const struct tcphdr *th; struct tcphdr _tcph; const char *fb_ptr; int ret; u32 seq; int dir = CTINFO2DIR(ctinfo); unsigned int uninitialized_var(matchlen), uninitialized_var(matchoff); struct nf_ct_ftp_master *ct_ftp_info = nfct_help_data(ct); struct nf_conntrack_expect *exp; union nf_inet_addr *daddr; struct nf_conntrack_man cmd = {}; unsigned int i; int found = 0, ends_in_nl; typeof(nf_nat_ftp_hook) nf_nat_ftp; /* Until there's been traffic both ways, don't look in packets. */ if (ctinfo != IP_CT_ESTABLISHED && ctinfo != IP_CT_ESTABLISHED_REPLY) { pr_debug("ftp: Conntrackinfo = %u\n", ctinfo); return NF_ACCEPT; } th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph); if (th == NULL) return NF_ACCEPT; dataoff = protoff + th->doff * 4; /* No data? */ if (dataoff >= skb->len) { pr_debug("ftp: dataoff(%u) >= skblen(%u)\n", dataoff, skb->len); return NF_ACCEPT; } datalen = skb->len - dataoff; spin_lock_bh(&nf_ftp_lock); fb_ptr = skb_header_pointer(skb, dataoff, datalen, ftp_buffer); BUG_ON(fb_ptr == NULL); ends_in_nl = (fb_ptr[datalen - 1] == '\n'); seq = ntohl(th->seq) + datalen; /* Look up to see if we're just after a \n. */ if (!find_nl_seq(ntohl(th->seq), ct_ftp_info, dir)) { /* We're picking up this, clear flags and let it continue */ if (unlikely(ct_ftp_info->flags[dir] & NF_CT_FTP_SEQ_PICKUP)) { ct_ftp_info->flags[dir] ^= NF_CT_FTP_SEQ_PICKUP; goto skip_nl_seq; } /* Now if this ends in \n, update ftp info. */ pr_debug("nf_conntrack_ftp: wrong seq pos %s(%u) or %s(%u)\n", ct_ftp_info->seq_aft_nl_num[dir] > 0 ? "" : "(UNSET)", ct_ftp_info->seq_aft_nl[dir][0], ct_ftp_info->seq_aft_nl_num[dir] > 1 ? "" : "(UNSET)", ct_ftp_info->seq_aft_nl[dir][1]); ret = NF_ACCEPT; goto out_update_nl; } skip_nl_seq: /* Initialize IP/IPv6 addr to expected address (it's not mentioned in EPSV responses) */ cmd.l3num = nf_ct_l3num(ct); memcpy(cmd.u3.all, &ct->tuplehash[dir].tuple.src.u3.all, sizeof(cmd.u3.all)); for (i = 0; i < ARRAY_SIZE(search[dir]); i++) { found = find_pattern(fb_ptr, datalen, search[dir][i].pattern, search[dir][i].plen, search[dir][i].skip, search[dir][i].term, &matchoff, &matchlen, &cmd, search[dir][i].getnum); if (found) break; } if (found == -1) { /* We don't usually drop packets. After all, this is connection tracking, not packet filtering. However, it is necessary for accurate tracking in this case. */ nf_ct_helper_log(skb, ct, "partial matching of `%s'", search[dir][i].pattern); ret = NF_DROP; goto out; } else if (found == 0) { /* No match */ ret = NF_ACCEPT; goto out_update_nl; } pr_debug("conntrack_ftp: match `%.*s' (%u bytes at %u)\n", matchlen, fb_ptr + matchoff, matchlen, ntohl(th->seq) + matchoff); exp = nf_ct_expect_alloc(ct); if (exp == NULL) { nf_ct_helper_log(skb, ct, "cannot alloc expectation"); ret = NF_DROP; goto out; } /* We refer to the reverse direction ("!dir") tuples here, * because we're expecting something in the other direction. * Doesn't matter unless NAT is happening. */ daddr = &ct->tuplehash[!dir].tuple.dst.u3; /* Update the ftp info */ if ((cmd.l3num == nf_ct_l3num(ct)) && memcmp(&cmd.u3.all, &ct->tuplehash[dir].tuple.src.u3.all, sizeof(cmd.u3.all))) { /* Enrico Scholz's passive FTP to partially RNAT'd ftp server: it really wants us to connect to a different IP address. Simply don't record it for NAT. */ if (cmd.l3num == PF_INET) { pr_debug("NOT RECORDING: %pI4 != %pI4\n", &cmd.u3.ip, &ct->tuplehash[dir].tuple.src.u3.ip); } else { pr_debug("NOT RECORDING: %pI6 != %pI6\n", cmd.u3.ip6, ct->tuplehash[dir].tuple.src.u3.ip6); } /* Thanks to Cristiano Lincoln Mattos <lincoln@cesar.org.br> for reporting this potential problem (DMZ machines opening holes to internal networks, or the packet filter itself). */ if (!loose) { ret = NF_ACCEPT; goto out_put_expect; } daddr = &cmd.u3; } nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, cmd.l3num, &ct->tuplehash[!dir].tuple.src.u3, daddr, IPPROTO_TCP, NULL, &cmd.u.tcp.port); /* Now, NAT might want to mangle the packet, and register the * (possibly changed) expectation itself. */ nf_nat_ftp = rcu_dereference(nf_nat_ftp_hook); if (nf_nat_ftp && ct->status & IPS_NAT_MASK) ret = nf_nat_ftp(skb, ctinfo, search[dir][i].ftptype, protoff, matchoff, matchlen, exp); else { /* Can't expect this? Best to drop packet now. */ if (nf_ct_expect_related(exp) != 0) { nf_ct_helper_log(skb, ct, "cannot add expectation"); ret = NF_DROP; } else ret = NF_ACCEPT; } out_put_expect: nf_ct_expect_put(exp); out_update_nl: /* Now if this ends in \n, update ftp info. Seq may have been * adjusted by NAT code. */ if (ends_in_nl) update_nl_seq(ct, seq, ct_ftp_info, dir, skb); out: spin_unlock_bh(&nf_ftp_lock); return ret; }

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yasuyuki kozakaiyasuyuki kozakai74780.67%14.35%
patrick mchardypatrick mchardy828.86%834.78%
pablo neira ayusopablo neira ayuso606.48%417.39%
herbert xuherbert xu80.86%14.35%
jozsef kadlecsikjozsef kadlecsik70.76%14.35%
jan engelhardtjan engelhardt70.76%28.70%
ingo molnaringo molnar60.65%14.35%
hideaki yoshifujihideaki yoshifuji20.22%14.35%
harald welteharald welte20.22%14.35%
harvey harrisonharvey harrison20.22%14.35%
alexey dobriyanalexey dobriyan20.22%14.35%
eric dumazeteric dumazet10.11%14.35%
Total926100.00%23100.00%


static int nf_ct_ftp_from_nlattr(struct nlattr *attr, struct nf_conn *ct) { struct nf_ct_ftp_master *ftp = nfct_help_data(ct); /* This conntrack has been injected from user-space, always pick up * sequence tracking. Otherwise, the first FTP command after the * failover breaks. */ ftp->flags[IP_CT_DIR_ORIGINAL] |= NF_CT_FTP_SEQ_PICKUP; ftp->flags[IP_CT_DIR_REPLY] |= NF_CT_FTP_SEQ_PICKUP; return 0; }

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pablo neira ayusopablo neira ayuso48100.00%1100.00%
Total48100.00%1100.00%

static struct nf_conntrack_helper ftp[MAX_PORTS * 2] __read_mostly; static const struct nf_conntrack_expect_policy ftp_exp_policy = { .max_expected = 1, .timeout = 5 * 60, }; /* don't make this __exit, since it's called from __init ! */
static void nf_conntrack_ftp_fini(void) {