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105 lines
3.7 KiB
105 lines
3.7 KiB
From: Jeff Mahoney <jeffm@suse.com>
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Subject: netfilter: Implement RFC 1123 for FTP conntrack
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References: bnc#466279
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Patch-mainline: Submitted via http://bugzilla.netfilter.org/show_bug.cgi?id=574 23 Jan 2011
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The FTP conntrack code currently only accepts the following format for
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the 227 response for PASV:
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227 Entering Passive Mode (148,100,81,40,31,161).
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It doesn't accept the following format from an obscure server:
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227 Data transfer will passively listen to 67,218,99,134,50,144
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From RFC 1123:
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The format of the 227 reply to a PASV command is not
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well standardized. In particular, an FTP client cannot
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assume that the parentheses shown on page 40 of RFC-959
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will be present (and in fact, Figure 3 on page 43 omits
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them). Therefore, a User-FTP program that interprets
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the PASV reply must scan the reply for the first digit
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of the host and port numbers.
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This patch adds support for the RFC 1123 clarification by:
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- Allowing a search filter to specify NUL as the terminator so that
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try_number will return successfully if the array of numbers has been
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filled when an unexpected character is encountered.
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- Using space as the separator for the 227 reply and then scanning for
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the first digit of the number sequence. The number sequence is parsed
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out using the existing try_rfc959 but with a NUL terminator.
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Tracked in: https://bugzilla.novell.com/show_bug.cgi?id=466279
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Reported-by: Mark Post <mpost@novell.com>
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Signed-off-by: Jeff Mahoney <jeffm@suse.com>
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---
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net/netfilter/nf_conntrack_ftp.c | 36 +++++++++++++++++++++++++++++++-----
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1 file changed, 31 insertions(+), 5 deletions(-)
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--- a/net/netfilter/nf_conntrack_ftp.c
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+++ b/net/netfilter/nf_conntrack_ftp.c
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@@ -53,6 +53,7 @@ unsigned int (*nf_nat_ftp_hook)(struct s
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EXPORT_SYMBOL_GPL(nf_nat_ftp_hook);
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static int try_rfc959(const char *, size_t, struct nf_conntrack_man *, char);
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+static int try_rfc1123(const char *, size_t, struct nf_conntrack_man *, char);
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static int try_eprt(const char *, size_t, struct nf_conntrack_man *, char);
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static int try_epsv_response(const char *, size_t, struct nf_conntrack_man *,
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char);
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@@ -87,10 +88,10 @@ static struct ftp_search {
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{
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.pattern = "227 ",
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.plen = sizeof("227 ") - 1,
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- .skip = '(',
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- .term = ')',
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+ .skip = ' ',
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+ .term = '\0',
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.ftptype = NF_CT_FTP_PASV,
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- .getnum = try_rfc959,
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+ .getnum = try_rfc1123,
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},
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{
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.pattern = "229 ",
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@@ -129,8 +130,9 @@ static int try_number(const char *data,
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i++;
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else {
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/* Unexpected character; true if it's the
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- terminator and we're finished. */
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- if (*data == term && i == array_size - 1)
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+ terminator (or we don't care about one)
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+ and we're finished. */
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+ if ((*data == term || !term) && i == array_size - 1)
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return len;
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pr_debug("Char %u (got %u nums) `%u' unexpected\n",
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@@ -160,6 +162,30 @@ static int try_rfc959(const char *data,
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return length;
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}
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+/*
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+ * From RFC 1123:
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+ * The format of the 227 reply to a PASV command is not
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+ * well standardized. In particular, an FTP client cannot
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+ * assume that the parentheses shown on page 40 of RFC-959
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+ * will be present (and in fact, Figure 3 on page 43 omits
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+ * them). Therefore, a User-FTP program that interprets
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+ * the PASV reply must scan the reply for the first digit
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+ * of the host and port numbers.
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+ */
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+static int try_rfc1123(const char *data, size_t dlen,
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+ struct nf_conntrack_man *cmd, char term)
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+{
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+ int i;
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+ for (i = 0; i < dlen; i++)
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+ if (isdigit(data[i]))
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+ break;
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+
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+ if (i == dlen)
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+ return 0;
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+
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+ return try_rfc959(data + i, dlen - i, cmd, 0);
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+}
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+
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/* Grab port: number up to delimiter */
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static int get_port(const char *data, int start, size_t dlen, char delim,
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__be16 *port)
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