/
daemon.c
1236 lines (1056 loc) · 27.5 KB
/
daemon.c
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#include "cache.h"
#include "pkt-line.h"
#include "exec_cmd.h"
#include "run-command.h"
#include "strbuf.h"
#include "string-list.h"
#ifndef HOST_NAME_MAX
#define HOST_NAME_MAX 256
#endif
#ifndef NI_MAXSERV
#define NI_MAXSERV 32
#endif
#ifdef NO_INITGROUPS
#define initgroups(x, y) (0) /* nothing */
#endif
static int log_syslog;
static int verbose;
static int reuseaddr;
static const char daemon_usage[] =
"git daemon [--verbose] [--syslog] [--export-all]\n"
" [--timeout=<n>] [--init-timeout=<n>] [--max-connections=<n>]\n"
" [--strict-paths] [--base-path=<path>] [--base-path-relaxed]\n"
" [--user-path | --user-path=<path>]\n"
" [--interpolated-path=<path>]\n"
" [--reuseaddr] [--pid-file=<file>]\n"
" [--(enable|disable|allow-override|forbid-override)=<service>]\n"
" [--inetd | [--listen=<host_or_ipaddr>] [--port=<n>]\n"
" [--detach] [--user=<user> [--group=<group>]]\n"
" [<directory>...]";
/* List of acceptable pathname prefixes */
static char **ok_paths;
static int strict_paths;
/* If this is set, git-daemon-export-ok is not required */
static int export_all_trees;
/* Take all paths relative to this one if non-NULL */
static char *base_path;
static char *interpolated_path;
static int base_path_relaxed;
/* Flag indicating client sent extra args. */
static int saw_extended_args;
/* If defined, ~user notation is allowed and the string is inserted
* after ~user/. E.g. a request to git://host/~alice/frotz would
* go to /home/alice/pub_git/frotz with --user-path=pub_git.
*/
static const char *user_path;
/* Timeout, and initial timeout */
static unsigned int timeout;
static unsigned int init_timeout;
static char *hostname;
static char *canon_hostname;
static char *ip_address;
static char *tcp_port;
static void logreport(int priority, const char *err, va_list params)
{
if (log_syslog) {
char buf[1024];
vsnprintf(buf, sizeof(buf), err, params);
syslog(priority, "%s", buf);
} else {
/*
* Since stderr is set to buffered mode, the
* logging of different processes will not overlap
* unless they overflow the (rather big) buffers.
*/
fprintf(stderr, "[%"PRIuMAX"] ", (uintmax_t)getpid());
vfprintf(stderr, err, params);
fputc('\n', stderr);
fflush(stderr);
}
}
__attribute__((format (printf, 1, 2)))
static void logerror(const char *err, ...)
{
va_list params;
va_start(params, err);
logreport(LOG_ERR, err, params);
va_end(params);
}
__attribute__((format (printf, 1, 2)))
static void loginfo(const char *err, ...)
{
va_list params;
if (!verbose)
return;
va_start(params, err);
logreport(LOG_INFO, err, params);
va_end(params);
}
static void NORETURN daemon_die(const char *err, va_list params)
{
logreport(LOG_ERR, err, params);
exit(1);
}
static char *path_ok(char *directory)
{
static char rpath[PATH_MAX];
static char interp_path[PATH_MAX];
char *path;
char *dir;
dir = directory;
if (daemon_avoid_alias(dir)) {
logerror("'%s': aliased", dir);
return NULL;
}
if (*dir == '~') {
if (!user_path) {
logerror("'%s': User-path not allowed", dir);
return NULL;
}
if (*user_path) {
/* Got either "~alice" or "~alice/foo";
* rewrite them to "~alice/%s" or
* "~alice/%s/foo".
*/
int namlen, restlen = strlen(dir);
char *slash = strchr(dir, '/');
if (!slash)
slash = dir + restlen;
namlen = slash - dir;
restlen -= namlen;
loginfo("userpath <%s>, request <%s>, namlen %d, restlen %d, slash <%s>", user_path, dir, namlen, restlen, slash);
snprintf(rpath, PATH_MAX, "%.*s/%s%.*s",
namlen, dir, user_path, restlen, slash);
dir = rpath;
}
}
else if (interpolated_path && saw_extended_args) {
struct strbuf expanded_path = STRBUF_INIT;
struct strbuf_expand_dict_entry dict[6];
dict[0].placeholder = "H"; dict[0].value = hostname;
dict[1].placeholder = "CH"; dict[1].value = canon_hostname;
dict[2].placeholder = "IP"; dict[2].value = ip_address;
dict[3].placeholder = "P"; dict[3].value = tcp_port;
dict[4].placeholder = "D"; dict[4].value = directory;
dict[5].placeholder = NULL; dict[5].value = NULL;
if (*dir != '/') {
/* Allow only absolute */
logerror("'%s': Non-absolute path denied (interpolated-path active)", dir);
return NULL;
}
strbuf_expand(&expanded_path, interpolated_path,
strbuf_expand_dict_cb, &dict);
strlcpy(interp_path, expanded_path.buf, PATH_MAX);
strbuf_release(&expanded_path);
loginfo("Interpolated dir '%s'", interp_path);
dir = interp_path;
}
else if (base_path) {
if (*dir != '/') {
/* Allow only absolute */
logerror("'%s': Non-absolute path denied (base-path active)", dir);
return NULL;
}
snprintf(rpath, PATH_MAX, "%s%s", base_path, dir);
dir = rpath;
}
path = enter_repo(dir, strict_paths);
if (!path && base_path && base_path_relaxed) {
/*
* if we fail and base_path_relaxed is enabled, try without
* prefixing the base path
*/
dir = directory;
path = enter_repo(dir, strict_paths);
}
if (!path) {
logerror("'%s' does not appear to be a git repository", dir);
return NULL;
}
if ( ok_paths && *ok_paths ) {
char **pp;
int pathlen = strlen(path);
/* The validation is done on the paths after enter_repo
* appends optional {.git,.git/.git} and friends, but
* it does not use getcwd(). So if your /pub is
* a symlink to /mnt/pub, you can whitelist /pub and
* do not have to say /mnt/pub.
* Do not say /pub/.
*/
for ( pp = ok_paths ; *pp ; pp++ ) {
int len = strlen(*pp);
if (len <= pathlen &&
!memcmp(*pp, path, len) &&
(path[len] == '\0' ||
(!strict_paths && path[len] == '/')))
return path;
}
}
else {
/* be backwards compatible */
if (!strict_paths)
return path;
}
logerror("'%s': not in whitelist", path);
return NULL; /* Fallthrough. Deny by default */
}
typedef int (*daemon_service_fn)(void);
struct daemon_service {
const char *name;
const char *config_name;
daemon_service_fn fn;
int enabled;
int overridable;
};
static struct daemon_service *service_looking_at;
static int service_enabled;
static int git_daemon_config(const char *var, const char *value, void *cb)
{
if (!prefixcmp(var, "daemon.") &&
!strcmp(var + 7, service_looking_at->config_name)) {
service_enabled = git_config_bool(var, value);
return 0;
}
/* we are not interested in parsing any other configuration here */
return 0;
}
static int run_service(char *dir, struct daemon_service *service)
{
const char *path;
int enabled = service->enabled;
loginfo("Request %s for '%s'", service->name, dir);
if (!enabled && !service->overridable) {
logerror("'%s': service not enabled.", service->name);
errno = EACCES;
return -1;
}
if (!(path = path_ok(dir)))
return -1;
/*
* Security on the cheap.
*
* We want a readable HEAD, usable "objects" directory, and
* a "git-daemon-export-ok" flag that says that the other side
* is ok with us doing this.
*
* path_ok() uses enter_repo() and does whitelist checking.
* We only need to make sure the repository is exported.
*/
if (!export_all_trees && access("git-daemon-export-ok", F_OK)) {
logerror("'%s': repository not exported.", path);
errno = EACCES;
return -1;
}
if (service->overridable) {
service_looking_at = service;
service_enabled = -1;
git_config(git_daemon_config, NULL);
if (0 <= service_enabled)
enabled = service_enabled;
}
if (!enabled) {
logerror("'%s': service not enabled for '%s'",
service->name, path);
errno = EACCES;
return -1;
}
/*
* We'll ignore SIGTERM from now on, we have a
* good client.
*/
signal(SIGTERM, SIG_IGN);
return service->fn();
}
static void copy_to_log(int fd)
{
struct strbuf line = STRBUF_INIT;
FILE *fp;
fp = fdopen(fd, "r");
if (fp == NULL) {
logerror("fdopen of error channel failed");
close(fd);
return;
}
while (strbuf_getline(&line, fp, '\n') != EOF) {
logerror("%s", line.buf);
strbuf_setlen(&line, 0);
}
strbuf_release(&line);
fclose(fp);
}
static int run_service_command(const char **argv)
{
struct child_process cld;
memset(&cld, 0, sizeof(cld));
cld.argv = argv;
cld.git_cmd = 1;
cld.err = -1;
if (start_command(&cld))
return -1;
close(0);
close(1);
copy_to_log(cld.err);
return finish_command(&cld);
}
static int upload_pack(void)
{
/* Timeout as string */
char timeout_buf[64];
const char *argv[] = { "upload-pack", "--strict", NULL, ".", NULL };
argv[2] = timeout_buf;
snprintf(timeout_buf, sizeof timeout_buf, "--timeout=%u", timeout);
return run_service_command(argv);
}
static int upload_archive(void)
{
static const char *argv[] = { "upload-archive", ".", NULL };
return run_service_command(argv);
}
static int receive_pack(void)
{
static const char *argv[] = { "receive-pack", ".", NULL };
return run_service_command(argv);
}
static struct daemon_service daemon_service[] = {
{ "upload-archive", "uploadarch", upload_archive, 0, 1 },
{ "upload-pack", "uploadpack", upload_pack, 1, 1 },
{ "receive-pack", "receivepack", receive_pack, 0, 1 },
};
static void enable_service(const char *name, int ena)
{
int i;
for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
if (!strcmp(daemon_service[i].name, name)) {
daemon_service[i].enabled = ena;
return;
}
}
die("No such service %s", name);
}
static void make_service_overridable(const char *name, int ena)
{
int i;
for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
if (!strcmp(daemon_service[i].name, name)) {
daemon_service[i].overridable = ena;
return;
}
}
die("No such service %s", name);
}
static char *xstrdup_tolower(const char *str)
{
char *p, *dup = xstrdup(str);
for (p = dup; *p; p++)
*p = tolower(*p);
return dup;
}
static void parse_host_and_port(char *hostport, char **host,
char **port)
{
if (*hostport == '[') {
char *end;
end = strchr(hostport, ']');
if (!end)
die("Invalid request ('[' without ']')");
*end = '\0';
*host = hostport + 1;
if (!end[1])
*port = NULL;
else if (end[1] == ':')
*port = end + 2;
else
die("Garbage after end of host part");
} else {
*host = hostport;
*port = strrchr(hostport, ':');
if (*port) {
**port = '\0';
++*port;
}
}
}
/*
* Read the host as supplied by the client connection.
*/
static void parse_host_arg(char *extra_args, int buflen)
{
char *val;
int vallen;
char *end = extra_args + buflen;
if (extra_args < end && *extra_args) {
saw_extended_args = 1;
if (strncasecmp("host=", extra_args, 5) == 0) {
val = extra_args + 5;
vallen = strlen(val) + 1;
if (*val) {
/* Split <host>:<port> at colon. */
char *host;
char *port;
parse_host_and_port(val, &host, &port);
if (port) {
free(tcp_port);
tcp_port = xstrdup(port);
}
free(hostname);
hostname = xstrdup_tolower(host);
}
/* On to the next one */
extra_args = val + vallen;
}
if (extra_args < end && *extra_args)
die("Invalid request");
}
/*
* Locate canonical hostname and its IP address.
*/
if (hostname) {
#ifndef NO_IPV6
struct addrinfo hints;
struct addrinfo *ai;
int gai;
static char addrbuf[HOST_NAME_MAX + 1];
memset(&hints, 0, sizeof(hints));
hints.ai_flags = AI_CANONNAME;
gai = getaddrinfo(hostname, NULL, &hints, &ai);
if (!gai) {
struct sockaddr_in *sin_addr = (void *)ai->ai_addr;
inet_ntop(AF_INET, &sin_addr->sin_addr,
addrbuf, sizeof(addrbuf));
free(ip_address);
ip_address = xstrdup(addrbuf);
free(canon_hostname);
canon_hostname = xstrdup(ai->ai_canonname ?
ai->ai_canonname : ip_address);
freeaddrinfo(ai);
}
#else
struct hostent *hent;
struct sockaddr_in sa;
char **ap;
static char addrbuf[HOST_NAME_MAX + 1];
hent = gethostbyname(hostname);
ap = hent->h_addr_list;
memset(&sa, 0, sizeof sa);
sa.sin_family = hent->h_addrtype;
sa.sin_port = htons(0);
memcpy(&sa.sin_addr, *ap, hent->h_length);
inet_ntop(hent->h_addrtype, &sa.sin_addr,
addrbuf, sizeof(addrbuf));
free(canon_hostname);
canon_hostname = xstrdup(hent->h_name);
free(ip_address);
ip_address = xstrdup(addrbuf);
#endif
}
}
static int execute(void)
{
static char line[1000];
int pktlen, len, i;
char *addr = getenv("REMOTE_ADDR"), *port = getenv("REMOTE_PORT");
if (addr)
loginfo("Connection from %s:%s", addr, port);
alarm(init_timeout ? init_timeout : timeout);
pktlen = packet_read_line(0, line, sizeof(line));
alarm(0);
len = strlen(line);
if (pktlen != len)
loginfo("Extended attributes (%d bytes) exist <%.*s>",
(int) pktlen - len,
(int) pktlen - len, line + len + 1);
if (len && line[len-1] == '\n') {
line[--len] = 0;
pktlen--;
}
free(hostname);
free(canon_hostname);
free(ip_address);
free(tcp_port);
hostname = canon_hostname = ip_address = tcp_port = NULL;
if (len != pktlen)
parse_host_arg(line + len + 1, pktlen - len - 1);
for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
struct daemon_service *s = &(daemon_service[i]);
int namelen = strlen(s->name);
if (!prefixcmp(line, "git-") &&
!strncmp(s->name, line + 4, namelen) &&
line[namelen + 4] == ' ') {
/*
* Note: The directory here is probably context sensitive,
* and might depend on the actual service being performed.
*/
return run_service(line + namelen + 5, s);
}
}
logerror("Protocol error: '%s'", line);
return -1;
}
static int addrcmp(const struct sockaddr_storage *s1,
const struct sockaddr_storage *s2)
{
const struct sockaddr *sa1 = (const struct sockaddr*) s1;
const struct sockaddr *sa2 = (const struct sockaddr*) s2;
if (sa1->sa_family != sa2->sa_family)
return sa1->sa_family - sa2->sa_family;
if (sa1->sa_family == AF_INET)
return memcmp(&((struct sockaddr_in *)s1)->sin_addr,
&((struct sockaddr_in *)s2)->sin_addr,
sizeof(struct in_addr));
#ifndef NO_IPV6
if (sa1->sa_family == AF_INET6)
return memcmp(&((struct sockaddr_in6 *)s1)->sin6_addr,
&((struct sockaddr_in6 *)s2)->sin6_addr,
sizeof(struct in6_addr));
#endif
return 0;
}
static int max_connections = 32;
static unsigned int live_children;
static struct child {
struct child *next;
struct child_process cld;
struct sockaddr_storage address;
} *firstborn;
static void add_child(struct child_process *cld, struct sockaddr *addr, socklen_t addrlen)
{
struct child *newborn, **cradle;
newborn = xcalloc(1, sizeof(*newborn));
live_children++;
memcpy(&newborn->cld, cld, sizeof(*cld));
memcpy(&newborn->address, addr, addrlen);
for (cradle = &firstborn; *cradle; cradle = &(*cradle)->next)
if (!addrcmp(&(*cradle)->address, &newborn->address))
break;
newborn->next = *cradle;
*cradle = newborn;
}
/*
* This gets called if the number of connections grows
* past "max_connections".
*
* We kill the newest connection from a duplicate IP.
*/
static void kill_some_child(void)
{
const struct child *blanket, *next;
if (!(blanket = firstborn))
return;
for (; (next = blanket->next); blanket = next)
if (!addrcmp(&blanket->address, &next->address)) {
kill(blanket->cld.pid, SIGTERM);
break;
}
}
static void check_dead_children(void)
{
int status;
pid_t pid;
struct child **cradle, *blanket;
for (cradle = &firstborn; (blanket = *cradle);)
if ((pid = waitpid(blanket->cld.pid, &status, WNOHANG)) > 1) {
const char *dead = "";
if (status)
dead = " (with error)";
loginfo("[%"PRIuMAX"] Disconnected%s", (uintmax_t)pid, dead);
/* remove the child */
*cradle = blanket->next;
live_children--;
free(blanket);
} else
cradle = &blanket->next;
}
static char **cld_argv;
static void handle(int incoming, struct sockaddr *addr, socklen_t addrlen)
{
struct child_process cld = { NULL };
char addrbuf[300] = "REMOTE_ADDR=", portbuf[300];
char *env[] = { addrbuf, portbuf, NULL };
if (max_connections && live_children >= max_connections) {
kill_some_child();
sleep(1); /* give it some time to die */
check_dead_children();
if (live_children >= max_connections) {
close(incoming);
logerror("Too many children, dropping connection");
return;
}
}
if (addr->sa_family == AF_INET) {
struct sockaddr_in *sin_addr = (void *) addr;
inet_ntop(addr->sa_family, &sin_addr->sin_addr, addrbuf + 12,
sizeof(addrbuf) - 12);
snprintf(portbuf, sizeof(portbuf), "REMOTE_PORT=%d",
ntohs(sin_addr->sin_port));
#ifndef NO_IPV6
} else if (addr && addr->sa_family == AF_INET6) {
struct sockaddr_in6 *sin6_addr = (void *) addr;
char *buf = addrbuf + 12;
*buf++ = '['; *buf = '\0'; /* stpcpy() is cool */
inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf,
sizeof(addrbuf) - 13);
strcat(buf, "]");
snprintf(portbuf, sizeof(portbuf), "REMOTE_PORT=%d",
ntohs(sin6_addr->sin6_port));
#endif
}
cld.env = (const char **)env;
cld.argv = (const char **)cld_argv;
cld.in = incoming;
cld.out = dup(incoming);
if (start_command(&cld))
logerror("unable to fork");
else
add_child(&cld, addr, addrlen);
close(incoming);
}
static void child_handler(int signo)
{
/*
* Otherwise empty handler because systemcalls will get interrupted
* upon signal receipt
* SysV needs the handler to be rearmed
*/
signal(SIGCHLD, child_handler);
}
static int set_reuse_addr(int sockfd)
{
int on = 1;
if (!reuseaddr)
return 0;
return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
&on, sizeof(on));
}
struct socketlist {
int *list;
size_t nr;
size_t alloc;
};
#ifndef NO_IPV6
static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
{
int socknum = 0;
int maxfd = -1;
char pbuf[NI_MAXSERV];
struct addrinfo hints, *ai0, *ai;
int gai;
long flags;
sprintf(pbuf, "%d", listen_port);
memset(&hints, 0, sizeof(hints));
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
hints.ai_protocol = IPPROTO_TCP;
hints.ai_flags = AI_PASSIVE;
gai = getaddrinfo(listen_addr, pbuf, &hints, &ai0);
if (gai) {
logerror("getaddrinfo() for %s failed: %s", listen_addr, gai_strerror(gai));
return 0;
}
for (ai = ai0; ai; ai = ai->ai_next) {
int sockfd;
sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
if (sockfd < 0)
continue;
if (sockfd >= FD_SETSIZE) {
logerror("Socket descriptor too large");
close(sockfd);
continue;
}
#ifdef IPV6_V6ONLY
if (ai->ai_family == AF_INET6) {
int on = 1;
setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
&on, sizeof(on));
/* Note: error is not fatal */
}
#endif
if (set_reuse_addr(sockfd)) {
close(sockfd);
continue;
}
if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
close(sockfd);
continue; /* not fatal */
}
if (listen(sockfd, 5) < 0) {
close(sockfd);
continue; /* not fatal */
}
flags = fcntl(sockfd, F_GETFD, 0);
if (flags >= 0)
fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
socklist->list[socklist->nr++] = sockfd;
socknum++;
if (maxfd < sockfd)
maxfd = sockfd;
}
freeaddrinfo(ai0);
return socknum;
}
#else /* NO_IPV6 */
static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
{
struct sockaddr_in sin;
int sockfd;
long flags;
memset(&sin, 0, sizeof sin);
sin.sin_family = AF_INET;
sin.sin_port = htons(listen_port);
if (listen_addr) {
/* Well, host better be an IP address here. */
if (inet_pton(AF_INET, listen_addr, &sin.sin_addr.s_addr) <= 0)
return 0;
} else {
sin.sin_addr.s_addr = htonl(INADDR_ANY);
}
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd < 0)
return 0;
if (set_reuse_addr(sockfd)) {
close(sockfd);
return 0;
}
if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
close(sockfd);
return 0;
}
if (listen(sockfd, 5) < 0) {
close(sockfd);
return 0;
}
flags = fcntl(sockfd, F_GETFD, 0);
if (flags >= 0)
fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
socklist->list[socklist->nr++] = sockfd;
return 1;
}
#endif
static void socksetup(struct string_list *listen_addr, int listen_port, struct socketlist *socklist)
{
if (!listen_addr->nr)
setup_named_sock(NULL, listen_port, socklist);
else {
int i, socknum;
for (i = 0; i < listen_addr->nr; i++) {
socknum = setup_named_sock(listen_addr->items[i].string,
listen_port, socklist);
if (socknum == 0)
logerror("unable to allocate any listen sockets for host %s on port %u",
listen_addr->items[i].string, listen_port);
}
}
}
static int service_loop(struct socketlist *socklist)
{
struct pollfd *pfd;
int i;
pfd = xcalloc(socklist->nr, sizeof(struct pollfd));
for (i = 0; i < socklist->nr; i++) {
pfd[i].fd = socklist->list[i];
pfd[i].events = POLLIN;
}
signal(SIGCHLD, child_handler);
for (;;) {
int i;
check_dead_children();
if (poll(pfd, socklist->nr, -1) < 0) {
if (errno != EINTR) {
logerror("Poll failed, resuming: %s",
strerror(errno));
sleep(1);
}
continue;
}
for (i = 0; i < socklist->nr; i++) {
if (pfd[i].revents & POLLIN) {
union {
struct sockaddr sa;
struct sockaddr_in sai;
#ifndef NO_IPV6
struct sockaddr_in6 sai6;
#endif
} ss;
socklen_t sslen = sizeof(ss);
int incoming = accept(pfd[i].fd, &ss.sa, &sslen);
if (incoming < 0) {
switch (errno) {
case EAGAIN:
case EINTR:
case ECONNABORTED:
continue;
default:
die_errno("accept returned");
}
}
handle(incoming, &ss.sa, sslen);
}
}
}
}
/* if any standard file descriptor is missing open it to /dev/null */
static void sanitize_stdfds(void)
{
int fd = open("/dev/null", O_RDWR, 0);
while (fd != -1 && fd < 2)
fd = dup(fd);
if (fd == -1)
die_errno("open /dev/null or dup failed");
if (fd > 2)
close(fd);
}
#ifdef NO_POSIX_GOODIES
struct credentials;
static void drop_privileges(struct credentials *cred)
{
/* nothing */
}
static void daemonize(void)
{
die("--detach not supported on this platform");
}
static struct credentials *prepare_credentials(const char *user_name,
const char *group_name)
{
die("--user not supported on this platform");
}
#else
struct credentials {
struct passwd *pass;
gid_t gid;
};
static void drop_privileges(struct credentials *cred)
{
if (cred && (initgroups(cred->pass->pw_name, cred->gid) ||
setgid (cred->gid) || setuid(cred->pass->pw_uid)))
die("cannot drop privileges");
}
static struct credentials *prepare_credentials(const char *user_name,
const char *group_name)
{
static struct credentials c;
c.pass = getpwnam(user_name);
if (!c.pass)
die("user not found - %s", user_name);
if (!group_name)
c.gid = c.pass->pw_gid;
else {
struct group *group = getgrnam(group_name);
if (!group)
die("group not found - %s", group_name);
c.gid = group->gr_gid;
}
return &c;