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* Increased size of l_links[] to be large enough for using the maximal #5

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* Increased size of l_links[] to be large enough for using the maximal #5

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e20d439
* Increased size of l_links[] to be large enough for using the maximal
Jan 20, 2021
e8f2d20
test
Jan 20, 2021
69c7adf
fixed potential out-of-bounds access when l_prefix=128
Nov 24, 2022
317ba16
Simplyfied inserting into link list.
Nov 24, 2022
3d77c41
Indent using spaces instead of tabs
Nov 24, 2022
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58 changes: 30 additions & 28 deletions ifaddrs.c
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Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,9 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include <netinet/in.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include <linux/if_packet.h> // struct sockaddr_ll
#include <stddef.h> // offsetof


typedef struct NetlinkList
{
Expand Down Expand Up @@ -86,7 +89,6 @@ static int netlink_recv(int p_socket, void *p_buffer, size_t p_len)
struct msghdr l_msg;
struct iovec l_iov = { p_buffer, p_len };
struct sockaddr_nl l_addr;
int l_result;

for(;;)
{
Expand All @@ -97,8 +99,12 @@ static int netlink_recv(int p_socket, void *p_buffer, size_t p_len)
l_msg.msg_control = NULL;
l_msg.msg_controllen = 0;
l_msg.msg_flags = 0;
int l_result = recvmsg(p_socket, &l_msg, 0);


int l_result = recvmsg(p_socket, &l_msg, MSG_PEEK | MSG_TRUNC);
if (l_result > p_len)// buffer was too small
return -1;

l_result = recvmsg(p_socket, &l_msg, 0);
if(l_result < 0)
{
if(errno == EINTR)
Expand All @@ -107,11 +113,6 @@ static int netlink_recv(int p_socket, void *p_buffer, size_t p_len)
}
return -2;
}

if(l_msg.msg_flags & MSG_TRUNC)
{ // buffer was too small
return -1;
}
return l_result;
}
}
Expand Down Expand Up @@ -192,11 +193,11 @@ static NetlinkList *getResultList(int p_socket, int p_request)
}

NetlinkList *l_list = NULL;
NetlinkList *l_end = NULL;
int l_size;
NetlinkList **l_current = &l_list;
int l_done = 0;
while(!l_done)
{
int l_size;
struct nlmsghdr *l_hdr = getNetlinkResponse(p_socket, &l_size, &l_done);
if(!l_hdr)
{ // error
Expand All @@ -205,15 +206,8 @@ static NetlinkList *getResultList(int p_socket, int p_request)
}

NetlinkList *l_item = newListItem(l_hdr, l_size);
if(!l_list)
{
l_list = l_item;
}
else
{
l_end->m_next = l_item;
}
l_end = l_item;
*l_current = newListItem(l_hdr, l_size);
l_current = &(*l_current)->m_next;
}
return l_list;
}
Expand Down Expand Up @@ -289,6 +283,7 @@ static void interpretLink(struct nlmsghdr *p_hdr, struct ifaddrs **p_links, stru
for(l_rta = (struct rtattr *)(((char *)l_info) + NLMSG_ALIGN(sizeof(struct ifinfomsg))); RTA_OK(l_rta, l_rtaSize); l_rta = RTA_NEXT(l_rta, l_rtaSize))
{
void *l_rtaData = RTA_DATA(l_rta);
(void)l_rtaData;
size_t l_rtaDataSize = RTA_PAYLOAD(l_rta);
switch(l_rta->rta_type)
{
Expand Down Expand Up @@ -374,6 +369,7 @@ static void interpretAddr(struct nlmsghdr *p_hdr, struct ifaddrs **p_links, stru
for(l_rta = (struct rtattr *)(((char *)l_info) + NLMSG_ALIGN(sizeof(struct ifaddrmsg))); RTA_OK(l_rta, l_rtaSize); l_rta = RTA_NEXT(l_rta, l_rtaSize))
{
void *l_rtaData = RTA_DATA(l_rta);
(void)l_rtaData;
size_t l_rtaDataSize = RTA_PAYLOAD(l_rta);
if(l_info->ifa_family == AF_PACKET)
{
Expand Down Expand Up @@ -471,12 +467,16 @@ static void interpretAddr(struct nlmsghdr *p_hdr, struct ifaddrs **p_links, stru
unsigned l_maxPrefix = (l_entry->ifa_addr->sa_family == AF_INET ? 32 : 128);
unsigned l_prefix = (l_info->ifa_prefixlen > l_maxPrefix ? l_maxPrefix : l_info->ifa_prefixlen);
char l_mask[16] = {0};
memset(l_mask, 0, sizeof(l_mask));
unsigned i;
for(i=0; i<(l_prefix/8); ++i)
{
l_mask[i] = 0xff;
}
l_mask[i] = 0xff << (8 - (l_prefix % 8));
if (i<sizeof(l_mask))
{
l_mask[i] = 0xff << (8 - (l_prefix % 8));
}

makeSockaddr(l_entry->ifa_addr->sa_family, (struct sockaddr *)l_addr, l_mask, l_maxPrefix / 8);
l_entry->ifa_netmask = (struct sockaddr *)l_addr;
Expand Down Expand Up @@ -516,9 +516,9 @@ static void interpret(int p_socket, NetlinkList *p_netlinkList, struct ifaddrs *
}
}

static unsigned countLinks(int p_socket, NetlinkList *p_netlinkList)
static unsigned get_max_ifi_index(int p_socket, NetlinkList *p_netlinkList)
{
unsigned l_links = 0;
unsigned l_max_ifi_index = 0;
pid_t l_pid = getpid();
for(; p_netlinkList; p_netlinkList = p_netlinkList->m_next)
{
Expand All @@ -538,12 +538,14 @@ static unsigned countLinks(int p_socket, NetlinkList *p_netlinkList)

if(l_hdr->nlmsg_type == RTM_NEWLINK)
{
++l_links;
struct ifinfomsg *l_info = (struct ifinfomsg *)NLMSG_DATA(l_hdr);
if (l_max_ifi_index < l_info->ifi_index)
l_max_ifi_index = l_info->ifi_index;
}
}
}

return l_links;
return l_max_ifi_index;
}

int getifaddrs(struct ifaddrs **ifap)
Expand Down Expand Up @@ -575,10 +577,10 @@ int getifaddrs(struct ifaddrs **ifap)
return -1;
}

unsigned l_numLinks = countLinks(l_socket, l_linkResults) + countLinks(l_socket, l_addrResults);
struct ifaddrs *l_links[l_numLinks];
memset(l_links, 0, l_numLinks * sizeof(struct ifaddrs *));
unsigned l_max_ifi_index = get_max_ifi_index(l_socket, l_linkResults) + get_max_ifi_index(l_socket, l_addrResults);
struct ifaddrs *l_links[l_max_ifi_index];
memset(l_links, 0, l_max_ifi_index * sizeof(struct ifaddrs *));

interpret(l_socket, l_linkResults, l_links, ifap);
interpret(l_socket, l_addrResults, l_links, ifap);

Expand Down