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Added option to use network namespace when connecting to parasite #82

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merged 1 commit into from
Jan 19, 2024
Merged

Added option to use network namespace when connecting to parasite #82

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60 changes: 57 additions & 3 deletions memcr.c
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Original file line number Diff line number Diff line change
Expand Up @@ -112,6 +112,7 @@ struct vm_area {

static char *dump_dir;
static char *parasite_socket_dir;
static int parasite_socket_use_netns;
static int no_wait;
static int proc_mem;
static int rss_file;
Expand Down Expand Up @@ -591,16 +592,62 @@ static int unseize_target(void)
return ret;
}

static int parasite_socket_create(pid_t pid)
{
int pid_netns = -1;
int cur_netns = -1;
char netns_path[64];
int cd;

if (parasite_socket_use_netns) {
/* get both current and parasite network namespaces */
snprintf(netns_path, sizeof(netns_path), "/proc/%d/ns/net", pid);
pid_netns = open(netns_path, O_CLOEXEC | O_RDONLY);
if (pid_netns < 0) {
fprintf(stderr, "open('%s', ) failed: %m\n", netns_path);
} else {
cur_netns = open("/proc/self/ns/net", O_CLOEXEC | O_RDONLY);
if (cur_netns < 0) {
fprintf(stderr, "open('/proc/self/ns/net', ) failed: %m\n");
close(pid_netns);
pid_netns = -1;
}
}

/* switch to network namespace of parasite if available */
if (pid_netns >= 0) {
if (setns(pid_netns, CLONE_NEWNET) != 0) {
fprintf(stderr, "setns() failed: %m\n");
}
close(pid_netns);
}
}

cd = socket(PF_UNIX, SOCK_STREAM | SOCK_NONBLOCK | SOCK_CLOEXEC, 0);
if (cd < 0) {
fprintf(stderr, "socket() failed: %m\n");
}

/* restore original network namespace if available */
if (cur_netns >= 0) {
if (setns(cur_netns, CLONE_NEWNET) != 0) {
fprintf(stderr, "setns() failed: %m\n");
}
close(cur_netns);
}

return cd;
}

static int parasite_connect(pid_t pid)
{
int cd;
struct sockaddr_un addr;
int ret;
int cnt = 0;

cd = socket(PF_UNIX, SOCK_STREAM | SOCK_NONBLOCK, 0);
cd = parasite_socket_create(pid);
if (cd < 0) {
fprintf(stderr, "socket() failed: %m\n");
return -1;
}

Expand Down Expand Up @@ -2743,6 +2790,8 @@ static void usage(const char *name, int status)
" -d --dir dir where memory dump is stored (defaults to /tmp)\n" \
" -S --parasite-socket-dir dir where socket to communicate with parasite is created\n" \
" (abstract socket will be used if no path specified)\n" \
" -N --parasite-socket-netns use network namespace of parasite when connecting to socket\n" \
" (useful if parasite is running in a container with netns)\n" \
" -l --listen work as a service waiting for requests on a socket\n" \
" -l PORT: TCP port number to listen for requests on\n" \
" -l PATH: filesystem path for UNIX domain socket file (will be created)\n" \
Expand Down Expand Up @@ -2783,6 +2832,7 @@ int main(int argc, char *argv[])
{ "pid", 1, NULL, 'p'},
{ "dir", 1, NULL, 'd'},
{ "parasite-socket-dir", 1, NULL, 'S'},
{ "parasite-socket-netns", 0, NULL, 'N'},
{ "listen", 1, NULL, 'l'},
{ "no-wait", 0, NULL, 'n'},
{ "proc-mem", 0, NULL, 'm'},
Expand All @@ -2795,8 +2845,9 @@ int main(int argc, char *argv[])

dump_dir = "/tmp";
parasite_socket_dir = NULL;
parasite_socket_use_netns = 0;

while ((opt = getopt_long(argc, argv, "hp:d:S:l:nmfzce::", long_options, &option_index)) != -1) {
while ((opt = getopt_long(argc, argv, "hp:d:S:Nl:nmfzce::", long_options, &option_index)) != -1) {
switch (opt) {
case 'h':
usage(argv[0], 0);
Expand All @@ -2810,6 +2861,9 @@ int main(int argc, char *argv[])
case 'S':
parasite_socket_dir = optarg;
break;
case 'N':
parasite_socket_use_netns = 1;
break;
case 'l':
listen_location = optarg;
service = 1;
Expand Down