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Date: Mon, 18 Mar 2024 08:27:21 -0700
From: Shradha Gupta <shradhagupta@linux.microsoft.com>
To: Ani Sinha <anisinha@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org,
	"K. Y. Srinivasan" <kys@microsoft.com>,
	Haiyang Zhang <haiyangz@microsoft.com>,
	Wei Liu <wei.liu@kernel.org>, Dexuan Cui <decui@microsoft.com>,
	Long Li <longli@microsoft.com>, Olaf Hering <olaf@aepfle.de>,
	Shradha Gupta <shradhagupta@microsoft.com>
Subject: Re: [PATCH v3] hv/hv_kvp_daemon: Handle IPv4 and Ipv6 combination
 for keyfile format
Message-ID: <20240318152721.GA9257@linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net>
References: <1710729951-2695-1-git-send-email-shradhagupta@linux.microsoft.com>
 <85394C37-16E1-4AA1-82D4-DEB3D58920A7@redhat.com>
 <56EA1869-5EFA-4515-AC39-965241C373BF@redhat.com>
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In-Reply-To: <56EA1869-5EFA-4515-AC39-965241C373BF@redhat.com>
User-Agent: Mutt/1.5.21 (2010-09-15)

On Mon, Mar 18, 2024 at 10:26:49AM +0530, Ani Sinha wrote:
> 
> 
> > On 18-Mar-2024, at 09:51, Ani Sinha <anisinha@redhat.com> wrote:
> > 
> > 
> > 
> >> On 18-Mar-2024, at 08:15, Shradha Gupta <shradhagupta@linux.microsoft.com> wrote:
> >> 
> >> If the network configuration strings are passed as a combination of IPv and
> >> IPv6 addresses, the current KVP daemon doesnot handle it for the keyfile
> >> configuration format.
> >> With these changes, the keyfile config generation logic scans through the
> >> list twice to generate IPv4 and IPv6 sections for the configuration files
> >> to handle this support.
> >> 
> >> Testcases ran:Rhel 9, Hyper-V VMs
> >>             (IPv4 only, IPv6 only, IPv4 and IPv6 combination)
> >> Signed-off-by: Shradha Gupta <shradhagupta@linux.microsoft.com>
> >> ---
> >> Changes in v3
> >> * Introduced a macro for the output string size
> >> * Added cound checks and used strncpy instead of strncpy
> >> * Rearranged code to reduce total lines of code
> >> ---
> >> tools/hv/hv_kvp_daemon.c | 177 ++++++++++++++++++++++++++++++---------
> >> 1 file changed, 136 insertions(+), 41 deletions(-)
> >> 
> >> diff --git a/tools/hv/hv_kvp_daemon.c b/tools/hv/hv_kvp_daemon.c
> >> index 318e2dad27e0..156cef99d361 100644
> >> --- a/tools/hv/hv_kvp_daemon.c
> >> +++ b/tools/hv/hv_kvp_daemon.c
> >> @@ -76,6 +76,12 @@ enum {
> >> DNS
> >> };
> >> 
> >> +enum {
> >> + IPV4 = 1,
> >> + IPV6,
> >> + IP_TYPE_MAX
> >> +};
> >> +
> >> static int in_hand_shake;
> >> 
> >> static char *os_name = "";
> >> @@ -102,6 +108,11 @@ static struct utsname uts_buf;
> >> 
> >> #define MAX_FILE_NAME 100
> >> #define ENTRIES_PER_BLOCK 50
> >> +/*
> >> + * Change this entry if the number of addresses increases in future
> >> + */
> >> +#define MAX_IP_ENTRIES 64
> >> +#define OUTSTR_BUF_SIZE ((INET6_ADDRSTRLEN + 1) * MAX_IP_ENTRIES)
> >> 
> >> struct kvp_record {
> >> char key[HV_KVP_EXCHANGE_MAX_KEY_SIZE];
> >> @@ -1171,6 +1182,18 @@ static int process_ip_string(FILE *f, char *ip_string, int type)
> >> return 0;
> >> }
> >> 
> >> +int ip_version_check(const char *input_addr)
> >> +{
> >> + struct in6_addr addr;
> >> +
> >> + if (inet_pton(AF_INET, input_addr, &addr))
> >> + return IPV4;
> >> + else if (inet_pton(AF_INET6, input_addr, &addr))
> >> + return IPV6;
> >> +
> >> + return -EINVAL;
> >> +}
> >> +
> >> /*
> >> * Only IPv4 subnet strings needs to be converted to plen
> >> * For IPv6 the subnet is already privided in plen format
> >> @@ -1197,14 +1220,71 @@ static int kvp_subnet_to_plen(char *subnet_addr_str)
> >> return plen;
> >> }
> >> 
> >> +static int process_dns_gateway_nm(FILE *f, char *ip_string, int type,
> >> +  int ip_sec)
> >> +{
> >> + char addr[INET6_ADDRSTRLEN], *output_str;
> >> + int ip_offset = 0, error = 0, ip_ver;
> >> + char *param_name;
> >> +
> >> + memset(addr, 0, sizeof(addr));
> > 
> > ^^^^^^^^^^^^^^^^^^^^^^^^
> > Is this still needed?
Nope, I'll get that.
> > 
> >> +
> >> + if (type == DNS)
> >> + param_name = "dns";
> >> + else if (type == GATEWAY)
> >> + param_name = "gateway";
> >> + else
> >> + return -EINVAL;
> >> +
> >> + output_str = (char *)calloc(OUTSTR_BUF_SIZE, sizeof(char));
> >> + if (!output_str)
> >> + return -ENOMEM;
> >> +
> >> + while (1) {
> >> + memset(addr, 0, sizeof(addr));
> >> +
> >> + if (!parse_ip_val_buffer(ip_string, &ip_offset, addr,
> >> + (MAX_IP_ADDR_SIZE * 2)))
> >> + break;
> >> +
> >> + ip_ver = ip_version_check(addr);
> >> + if (ip_ver < 0)
> >> + continue;
> >> +
> >> + if ((ip_ver == IPV4 && ip_sec == IPV4) ||
> >> +    (ip_ver == IPV6 && ip_sec == IPV6)) {
> >> + /*
> >> + * do a bound check to avoid out-of bound writes
> >> + */
> >> + if ((OUTSTR_BUF_SIZE - strlen(output_str)) >
> >> +    (strlen(addr) + 1)) {
> >> + strncat(output_str, addr,
> >> + OUTSTR_BUF_SIZE - strlen(output_str));
> >> + strncat(output_str, ",",
> > 
> > Please see man page for strncat(). Why is the third parameter simply not strlen(addr)? 
> 
> I see what you are trying to do. You are doing a bound check here. In that case, should this be
> OUTSTR_BUF_SIZE - strlen(output_str) - 1 to accommodate the terminating NULL? Man page says
> 
> > it will use at most n bytes from src
> 
> So n bytes from addr and one extra at the end for NULL termination since strncat () will add a terminating NULL byte in the end.
sure, that sounds right. Will get this too.
> 
> > 
> >> + OUTSTR_BUF_SIZE - strlen(output_str));
> > 
> > 
> > 
> >> + }
> >> + } else {
> >> + continue;
> >> + }
> >> + }
> >> +
> >> + if (strlen(output_str)) {
> > 
> > Please add the comment I mentioned in the previous version as to why you are doing this.
sure. Thanks
> > 
> >> + output_str[strlen(output_str) - 1] = '\0';
> >> + error = fprintf(f, "%s=%s\n", param_name, output_str);
> >> + }
> >> +
> >> + free(output_str);
> >> + return error;
> >> +}
> >> +
> >> static int process_ip_string_nm(FILE *f, char *ip_string, char *subnet,
> >> - int is_ipv6)
> >> + int ip_sec)
> >> {
> >> char addr[INET6_ADDRSTRLEN];
> >> char subnet_addr[INET6_ADDRSTRLEN];
> >> int error, i = 0;
> >> int ip_offset = 0, subnet_offset = 0;
> >> - int plen;
> >> + int plen, ip_ver;
> >> 
> >> memset(addr, 0, sizeof(addr));
> >> memset(subnet_addr, 0, sizeof(subnet_addr));
> >> @@ -1216,10 +1296,16 @@ static int process_ip_string_nm(FILE *f, char *ip_string, char *subnet,
> >>      subnet_addr,
> >>      (MAX_IP_ADDR_SIZE *
> >> 2))) {
> >> - if (!is_ipv6)
> >> + ip_ver = ip_version_check(addr);
> >> + if (ip_ver < 0)
> >> + continue;
> >> +
> >> + if (ip_ver == IPV4 && ip_sec == IPV4)
> >> plen = kvp_subnet_to_plen((char *)subnet_addr);
> >> - else
> >> + else if (ip_ver == IPV6 && ip_sec == IPV6)
> >> plen = atoi(subnet_addr);
> >> + else
> >> + continue;
> >> 
> >> if (plen < 0)
> >> return plen;
> >> @@ -1238,12 +1324,11 @@ static int process_ip_string_nm(FILE *f, char *ip_string, char *subnet,
> >> 
> >> static int kvp_set_ip_info(char *if_name, struct hv_kvp_ipaddr_value *new_val)
> >> {
> >> - int error = 0;
> >> + int error = 0, ip_ver;
> >> char if_filename[PATH_MAX];
> >> char nm_filename[PATH_MAX];
> >> FILE *ifcfg_file, *nmfile;
> >> char cmd[PATH_MAX];
> >> - int is_ipv6 = 0;
> >> char *mac_addr;
> >> int str_len;
> >> 
> >> @@ -1421,52 +1506,62 @@ static int kvp_set_ip_info(char *if_name, struct hv_kvp_ipaddr_value *new_val)
> >> if (error)
> >> goto setval_error;
> >> 
> >> - if (new_val->addr_family & ADDR_FAMILY_IPV6) {
> >> - error = fprintf(nmfile, "\n[ipv6]\n");
> >> - if (error < 0)
> >> - goto setval_error;
> >> - is_ipv6 = 1;
> >> - } else {
> >> - error = fprintf(nmfile, "\n[ipv4]\n");
> >> - if (error < 0)
> >> - goto setval_error;
> >> - }
> >> -
> >> /*
> >> - * Now we populate the keyfile format
> >> + * The keyfile format expects the IPv6 and IPv4 configuration in
> >> + * different sections. Therefore we iterate through the list twice,
> >> + * once to populate the IPv4 section and the next time for IPv6
> >> */
> >> + ip_ver = IPV4;
> >> + do {
> >> + if (ip_ver == IPV4) {
> >> + error = fprintf(nmfile, "\n[ipv4]\n");
> >> + if (error < 0)
> >> + goto setval_error;
> >> + } else {
> >> + error = fprintf(nmfile, "\n[ipv6]\n");
> >> + if (error < 0)
> >> + goto setval_error;
> >> + }
> >> 
> >> - if (new_val->dhcp_enabled) {
> >> - error = kvp_write_file(nmfile, "method", "", "auto");
> >> - if (error < 0)
> >> - goto setval_error;
> >> - } else {
> >> - error = kvp_write_file(nmfile, "method", "", "manual");
> >> + /*
> >> + * Now we populate the keyfile format
> >> + */
> >> +
> >> + if (new_val->dhcp_enabled) {
> >> + error = kvp_write_file(nmfile, "method", "", "auto");
> >> + if (error < 0)
> >> + goto setval_error;
> >> + } else {
> >> + error = kvp_write_file(nmfile, "method", "", "manual");
> >> + if (error < 0)
> >> + goto setval_error;
> >> + }
> >> +
> >> + /*
> >> + * Write the configuration for ipaddress, netmask, gateway and
> >> + * name services
> >> + */
> >> + error = process_ip_string_nm(nmfile, (char *)new_val->ip_addr,
> >> +     (char *)new_val->sub_net,
> >> +     ip_ver);
> >> if (error < 0)
> >> goto setval_error;
> >> - }
> >> 
> >> - /*
> >> - * Write the configuration for ipaddress, netmask, gateway and
> >> - * name services
> >> - */
> >> - error = process_ip_string_nm(nmfile, (char *)new_val->ip_addr,
> >> -     (char *)new_val->sub_net, is_ipv6);
> >> - if (error < 0)
> >> - goto setval_error;
> >> -
> >> - /* we do not want ipv4 addresses in ipv6 section and vice versa */
> >> - if (is_ipv6 != is_ipv4((char *)new_val->gate_way)) {
> >> - error = fprintf(nmfile, "gateway=%s\n", (char *)new_val->gate_way);
> >> + error = process_dns_gateway_nm(nmfile,
> >> +       (char *)new_val->gate_way,
> >> +       GATEWAY, ip_ver);
> >> if (error < 0)
> >> goto setval_error;
> >> - }
> >> 
> >> - if (is_ipv6 != is_ipv4((char *)new_val->dns_addr)) {
> >> - error = fprintf(nmfile, "dns=%s\n", (char *)new_val->dns_addr);
> >> + error = process_dns_gateway_nm(nmfile,
> >> +       (char *)new_val->dns_addr, DNS,
> >> +       ip_ver);
> >> if (error < 0)
> >> goto setval_error;
> >> - }
> >> +
> >> + ip_ver++;
> >> + } while (ip_ver < IP_TYPE_MAX);
> >> +
> >> fclose(nmfile);
> >> fclose(ifcfg_file);
> >> 
> >> -- 
> >> 2.34.1
>