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nwfilter: Instantiate comments in ip(6)tables rules

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In this patch I am extending the rule instantiator to create the comment
node where supported, which is the case for iptables and ip6tables.

Since commands are written in the format

cmd='iptables ...-m comment --comment \"\" '

certain characters ('`) in the comment need to be escaped to
prevent comments from becoming commands themselves or cause other
forms of (bash) substitutions. I have tested this with various input and in
my tests the input made it straight into the comment. A test case for TCK
will be provided separately that tests this.
This commit is contained in:
Stefan Berger 2010-09-30 15:56:09 -04:00
parent ec3d03db88
commit b00f41a1d2
2 changed files with 74 additions and 15 deletions
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87
src/nwfilter/nwfilter_ebiptables_driver.c
View File

@ -23,6 +23,7 @@
#include <config.h>
#include <string.h>
#include <sys/stat.h>
#include <fcntl.h>
@ -52,10 +53,10 @@
#define CMD_SEPARATOR "\n"
#define CMD_DEF_PRE "cmd=\""
#define CMD_DEF_POST "\""
#define CMD_DEF_PRE "cmd='"
#define CMD_DEF_POST "'"
#define CMD_DEF(X) CMD_DEF_PRE X CMD_DEF_POST
#define CMD_EXEC "res=`${cmd}`" CMD_SEPARATOR
#define CMD_EXEC "eval res=\\`\"${cmd}\"\\`" CMD_SEPARATOR
#define CMD_STOPONERR(X) \
X ? "if [ $? -ne 0 ]; then" \
" echo \"Failure to execute command '${cmd}'.\";" \
@ -106,6 +107,7 @@ static const char *m_physdev_out_str = "-m physdev " PHYSDEV_OUT;
#define MATCH_PHYSDEV_IN m_physdev_in_str
#define MATCH_PHYSDEV_OUT m_physdev_out_str
#define COMMENT_VARNAME "comment"
static int ebtablesRemoveBasicRules(const char *ifname);
static int ebiptablesDriverInit(void);
@ -291,6 +293,26 @@ printDataTypeAsHex(virNWFilterHashTablePtr vars,
}
static void
printCommentVar(virBufferPtr dest, const char *buf)
{
size_t i, len = strlen(buf);
virBufferAddLit(dest, COMMENT_VARNAME "='");
if (len > IPTABLES_MAX_COMMENT_LENGTH)
len = IPTABLES_MAX_COMMENT_LENGTH;
for (i = 0; i < len; i++) {
if (buf[i] == '\'')
virBufferAddLit(dest, "'\\''");
else
virBufferAddChar(dest, buf[i]);
}
virBufferAddLit(dest,"'" CMD_SEPARATOR);
}
static void
ebiptablesRuleInstFree(ebiptablesRuleInstPtr inst)
{
@ -846,7 +868,8 @@ iptablesHandleIpHdr(virBufferPtr buf,
virNWFilterHashTablePtr vars,
ipHdrDataDefPtr ipHdr,
int directionIn,
bool *skipRule, bool *skipMatch)
bool *skipRule, bool *skipMatch,
virBufferPtr prefix)
{
char ipaddr[INET6_ADDRSTRLEN],
number[20];
@ -993,6 +1016,13 @@ iptablesHandleIpHdr(virBufferPtr buf,
}
}
if (HAS_ENTRY_ITEM(&ipHdr->dataComment)) {
printCommentVar(prefix, ipHdr->dataComment.u.string);
virBufferAddLit(buf,
" -m comment --comment \"$" COMMENT_VARNAME "\"");
}
return 0;
err_exit:
@ -1106,7 +1136,9 @@ _iptablesCreateRuleInstance(int directionIn,
{
char chain[MAX_CHAINNAME_LENGTH];
char number[20];
virBuffer prefix = VIR_BUFFER_INITIALIZER;
virBuffer buf = VIR_BUFFER_INITIALIZER;
virBufferPtr final = NULL;
const char *target;
const char *iptables_cmd = (isIPv6) ? ip6tables_cmd_path
: iptables_cmd_path;
@ -1148,7 +1180,8 @@ _iptablesCreateRuleInstance(int directionIn,
vars,
&rule->p.tcpHdrFilter.ipHdr,
directionIn,
&skipRule, &skipMatch))
&skipRule, &skipMatch,
&prefix))
goto err_exit;
if (iptablesHandlePortData(&buf,
@ -1193,7 +1226,8 @@ _iptablesCreateRuleInstance(int directionIn,
vars,
&rule->p.udpHdrFilter.ipHdr,
directionIn,
&skipRule, &skipMatch))
&skipRule, &skipMatch,
&prefix))
goto err_exit;
if (iptablesHandlePortData(&buf,
@ -1225,7 +1259,8 @@ _iptablesCreateRuleInstance(int directionIn,
vars,
&rule->p.udpliteHdrFilter.ipHdr,
directionIn,
&skipRule, &skipMatch))
&skipRule, &skipMatch,
&prefix))
goto err_exit;
break;
@ -1252,7 +1287,8 @@ _iptablesCreateRuleInstance(int directionIn,
vars,
&rule->p.espHdrFilter.ipHdr,
directionIn,
&skipRule, &skipMatch))
&skipRule, &skipMatch,
&prefix))
goto err_exit;
break;
@ -1279,7 +1315,8 @@ _iptablesCreateRuleInstance(int directionIn,
vars,
&rule->p.ahHdrFilter.ipHdr,
directionIn,
&skipRule, &skipMatch))
&skipRule, &skipMatch,
&prefix))
goto err_exit;
break;
@ -1306,7 +1343,8 @@ _iptablesCreateRuleInstance(int directionIn,
vars,
&rule->p.sctpHdrFilter.ipHdr,
directionIn,
&skipRule, &skipMatch))
&skipRule, &skipMatch,
&prefix))
goto err_exit;
if (iptablesHandlePortData(&buf,
@ -1341,7 +1379,8 @@ _iptablesCreateRuleInstance(int directionIn,
vars,
&rule->p.icmpHdrFilter.ipHdr,
directionIn,
&skipRule, &skipMatch))
&skipRule, &skipMatch,
&prefix))
goto err_exit;
if (HAS_ENTRY_ITEM(&rule->p.icmpHdrFilter.dataICMPType)) {
@ -1400,7 +1439,8 @@ _iptablesCreateRuleInstance(int directionIn,
vars,
&rule->p.igmpHdrFilter.ipHdr,
directionIn,
&skipRule, &skipMatch))
&skipRule, &skipMatch,
&prefix))
goto err_exit;
break;
@ -1427,7 +1467,8 @@ _iptablesCreateRuleInstance(int directionIn,
vars,
&rule->p.allHdrFilter.ipHdr,
directionIn,
&skipRule, &skipMatch))
&skipRule, &skipMatch,
&prefix))
goto err_exit;
break;
@ -1439,6 +1480,7 @@ _iptablesCreateRuleInstance(int directionIn,
if ((srcMacSkipped && bufUsed == virBufferUse(&buf)) ||
skipRule) {
virBufferFreeAndReset(&buf);
virBufferFreeAndReset(&prefix);
return 0;
}
@ -1458,14 +1500,29 @@ _iptablesCreateRuleInstance(int directionIn,
CMD_EXEC,
target);
if (virBufferError(&buf)) {
if (virBufferError(&buf) || virBufferError(&prefix)) {
virBufferFreeAndReset(&buf);
virBufferFreeAndReset(&prefix);
virReportOOMError();
return -1;
}
if (virBufferUse(&prefix)) {
virBufferVSprintf(&prefix, "%s", virBufferContentAndReset(&buf));
final = &prefix;
if (virBufferError(&prefix)) {
virBufferFreeAndReset(&prefix);
virReportOOMError();
return -1;
}
} else
final = &buf;
return ebiptablesAddRuleInst(res,
virBufferContentAndReset(&buf),
virBufferContentAndReset(final),
nwfilter->chainsuffix,
'\0',
rule->priority,

2
src/nwfilter/nwfilter_ebiptables_driver.h
View File

@ -45,4 +45,6 @@ extern virNWFilterTechDriver ebiptables_driver;
# define EBIPTABLES_DRIVER_ID "ebiptables"
# define IPTABLES_MAX_COMMENT_LENGTH 256
#endif