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git/http-backend.c
Jeff King fcd12db6af prefer git_pathdup to git_path in some possibly-dangerous cases
Because git_path uses a static buffer that is shared with
calls to git_path, mkpath, etc, it can be dangerous to
assign the result to a variable or pass it to a non-trivial
function. The value may change unexpectedly due to other
calls.

None of the cases changed here has a known bug, but they're
worth converting away from git_path because:

  1. It's easy to use git_pathdup in these cases.

  2. They use constructs (like assignment) that make it
     hard to tell whether they're safe or not.

The extra malloc overhead should be trivial, as an
allocation should be an order of magnitude cheaper than a
system call (which we are clearly about to make, since we
are constructing a filename). The real cost is that we must
remember to free the result.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-10 15:37:12 -07:00

703 lines
16 KiB
C

#include "cache.h"
#include "refs.h"
#include "pkt-line.h"
#include "object.h"
#include "tag.h"
#include "exec_cmd.h"
#include "run-command.h"
#include "string-list.h"
#include "url.h"
#include "argv-array.h"
static const char content_type[] = "Content-Type";
static const char content_length[] = "Content-Length";
static const char last_modified[] = "Last-Modified";
static int getanyfile = 1;
static unsigned long max_request_buffer = 10 * 1024 * 1024;
static struct string_list *query_params;
struct rpc_service {
const char *name;
const char *config_name;
unsigned buffer_input : 1;
signed enabled : 2;
};
static struct rpc_service rpc_service[] = {
{ "upload-pack", "uploadpack", 1, 1 },
{ "receive-pack", "receivepack", 0, -1 },
};
static struct string_list *get_parameters(void)
{
if (!query_params) {
const char *query = getenv("QUERY_STRING");
query_params = xcalloc(1, sizeof(*query_params));
while (query && *query) {
char *name = url_decode_parameter_name(&query);
char *value = url_decode_parameter_value(&query);
struct string_list_item *i;
i = string_list_lookup(query_params, name);
if (!i)
i = string_list_insert(query_params, name);
else
free(i->util);
i->util = value;
}
}
return query_params;
}
static const char *get_parameter(const char *name)
{
struct string_list_item *i;
i = string_list_lookup(get_parameters(), name);
return i ? i->util : NULL;
}
__attribute__((format (printf, 2, 3)))
static void format_write(int fd, const char *fmt, ...)
{
static char buffer[1024];
va_list args;
unsigned n;
va_start(args, fmt);
n = vsnprintf(buffer, sizeof(buffer), fmt, args);
va_end(args);
if (n >= sizeof(buffer))
die("protocol error: impossibly long line");
write_or_die(fd, buffer, n);
}
static void http_status(unsigned code, const char *msg)
{
format_write(1, "Status: %u %s\r\n", code, msg);
}
static void hdr_str(const char *name, const char *value)
{
format_write(1, "%s: %s\r\n", name, value);
}
static void hdr_int(const char *name, uintmax_t value)
{
format_write(1, "%s: %" PRIuMAX "\r\n", name, value);
}
static void hdr_date(const char *name, unsigned long when)
{
const char *value = show_date(when, 0, DATE_MODE(RFC2822));
hdr_str(name, value);
}
static void hdr_nocache(void)
{
hdr_str("Expires", "Fri, 01 Jan 1980 00:00:00 GMT");
hdr_str("Pragma", "no-cache");
hdr_str("Cache-Control", "no-cache, max-age=0, must-revalidate");
}
static void hdr_cache_forever(void)
{
unsigned long now = time(NULL);
hdr_date("Date", now);
hdr_date("Expires", now + 31536000);
hdr_str("Cache-Control", "public, max-age=31536000");
}
static void end_headers(void)
{
write_or_die(1, "\r\n", 2);
}
__attribute__((format (printf, 1, 2)))
static NORETURN void not_found(const char *err, ...)
{
va_list params;
http_status(404, "Not Found");
hdr_nocache();
end_headers();
va_start(params, err);
if (err && *err)
vfprintf(stderr, err, params);
va_end(params);
exit(0);
}
__attribute__((format (printf, 1, 2)))
static NORETURN void forbidden(const char *err, ...)
{
va_list params;
http_status(403, "Forbidden");
hdr_nocache();
end_headers();
va_start(params, err);
if (err && *err)
vfprintf(stderr, err, params);
va_end(params);
exit(0);
}
static void select_getanyfile(void)
{
if (!getanyfile)
forbidden("Unsupported service: getanyfile");
}
static void send_strbuf(const char *type, struct strbuf *buf)
{
hdr_int(content_length, buf->len);
hdr_str(content_type, type);
end_headers();
write_or_die(1, buf->buf, buf->len);
}
static void send_local_file(const char *the_type, const char *name)
{
char *p = git_pathdup("%s", name);
size_t buf_alloc = 8192;
char *buf = xmalloc(buf_alloc);
int fd;
struct stat sb;
fd = open(p, O_RDONLY);
if (fd < 0)
not_found("Cannot open '%s': %s", p, strerror(errno));
if (fstat(fd, &sb) < 0)
die_errno("Cannot stat '%s'", p);
hdr_int(content_length, sb.st_size);
hdr_str(content_type, the_type);
hdr_date(last_modified, sb.st_mtime);
end_headers();
for (;;) {
ssize_t n = xread(fd, buf, buf_alloc);
if (n < 0)
die_errno("Cannot read '%s'", p);
if (!n)
break;
write_or_die(1, buf, n);
}
close(fd);
free(buf);
free(p);
}
static void get_text_file(char *name)
{
select_getanyfile();
hdr_nocache();
send_local_file("text/plain", name);
}
static void get_loose_object(char *name)
{
select_getanyfile();
hdr_cache_forever();
send_local_file("application/x-git-loose-object", name);
}
static void get_pack_file(char *name)
{
select_getanyfile();
hdr_cache_forever();
send_local_file("application/x-git-packed-objects", name);
}
static void get_idx_file(char *name)
{
select_getanyfile();
hdr_cache_forever();
send_local_file("application/x-git-packed-objects-toc", name);
}
static void http_config(void)
{
int i, value = 0;
struct strbuf var = STRBUF_INIT;
git_config_get_bool("http.getanyfile", &getanyfile);
git_config_get_ulong("http.maxrequestbuffer", &max_request_buffer);
for (i = 0; i < ARRAY_SIZE(rpc_service); i++) {
struct rpc_service *svc = &rpc_service[i];
strbuf_addf(&var, "http.%s", svc->config_name);
if (!git_config_get_bool(var.buf, &value))
svc->enabled = value;
strbuf_reset(&var);
}
strbuf_release(&var);
}
static struct rpc_service *select_service(const char *name)
{
const char *svc_name;
struct rpc_service *svc = NULL;
int i;
if (!skip_prefix(name, "git-", &svc_name))
forbidden("Unsupported service: '%s'", name);
for (i = 0; i < ARRAY_SIZE(rpc_service); i++) {
struct rpc_service *s = &rpc_service[i];
if (!strcmp(s->name, svc_name)) {
svc = s;
break;
}
}
if (!svc)
forbidden("Unsupported service: '%s'", name);
if (svc->enabled < 0) {
const char *user = getenv("REMOTE_USER");
svc->enabled = (user && *user) ? 1 : 0;
}
if (!svc->enabled)
forbidden("Service not enabled: '%s'", svc->name);
return svc;
}
/*
* This is basically strbuf_read(), except that if we
* hit max_request_buffer we die (we'd rather reject a
* maliciously large request than chew up infinite memory).
*/
static ssize_t read_request(int fd, unsigned char **out)
{
size_t len = 0, alloc = 8192;
unsigned char *buf = xmalloc(alloc);
if (max_request_buffer < alloc)
max_request_buffer = alloc;
while (1) {
ssize_t cnt;
cnt = read_in_full(fd, buf + len, alloc - len);
if (cnt < 0) {
free(buf);
return -1;
}
/* partial read from read_in_full means we hit EOF */
len += cnt;
if (len < alloc) {
*out = buf;
return len;
}
/* otherwise, grow and try again (if we can) */
if (alloc == max_request_buffer)
die("request was larger than our maximum size (%lu);"
" try setting GIT_HTTP_MAX_REQUEST_BUFFER",
max_request_buffer);
alloc = alloc_nr(alloc);
if (alloc > max_request_buffer)
alloc = max_request_buffer;
REALLOC_ARRAY(buf, alloc);
}
}
static void inflate_request(const char *prog_name, int out, int buffer_input)
{
git_zstream stream;
unsigned char *full_request = NULL;
unsigned char in_buf[8192];
unsigned char out_buf[8192];
unsigned long cnt = 0;
memset(&stream, 0, sizeof(stream));
git_inflate_init_gzip_only(&stream);
while (1) {
ssize_t n;
if (buffer_input) {
if (full_request)
n = 0; /* nothing left to read */
else
n = read_request(0, &full_request);
stream.next_in = full_request;
} else {
n = xread(0, in_buf, sizeof(in_buf));
stream.next_in = in_buf;
}
if (n <= 0)
die("request ended in the middle of the gzip stream");
stream.avail_in = n;
while (0 < stream.avail_in) {
int ret;
stream.next_out = out_buf;
stream.avail_out = sizeof(out_buf);
ret = git_inflate(&stream, Z_NO_FLUSH);
if (ret != Z_OK && ret != Z_STREAM_END)
die("zlib error inflating request, result %d", ret);
n = stream.total_out - cnt;
if (write_in_full(out, out_buf, n) != n)
die("%s aborted reading request", prog_name);
cnt += n;
if (ret == Z_STREAM_END)
goto done;
}
}
done:
git_inflate_end(&stream);
close(out);
free(full_request);
}
static void copy_request(const char *prog_name, int out)
{
unsigned char *buf;
ssize_t n = read_request(0, &buf);
if (n < 0)
die_errno("error reading request body");
if (write_in_full(out, buf, n) != n)
die("%s aborted reading request", prog_name);
close(out);
free(buf);
}
static void run_service(const char **argv, int buffer_input)
{
const char *encoding = getenv("HTTP_CONTENT_ENCODING");
const char *user = getenv("REMOTE_USER");
const char *host = getenv("REMOTE_ADDR");
int gzipped_request = 0;
struct child_process cld = CHILD_PROCESS_INIT;
if (encoding && !strcmp(encoding, "gzip"))
gzipped_request = 1;
else if (encoding && !strcmp(encoding, "x-gzip"))
gzipped_request = 1;
if (!user || !*user)
user = "anonymous";
if (!host || !*host)
host = "(none)";
if (!getenv("GIT_COMMITTER_NAME"))
argv_array_pushf(&cld.env_array, "GIT_COMMITTER_NAME=%s", user);
if (!getenv("GIT_COMMITTER_EMAIL"))
argv_array_pushf(&cld.env_array,
"GIT_COMMITTER_EMAIL=%s@http.%s", user, host);
cld.argv = argv;
if (buffer_input || gzipped_request)
cld.in = -1;
cld.git_cmd = 1;
if (start_command(&cld))
exit(1);
close(1);
if (gzipped_request)
inflate_request(argv[0], cld.in, buffer_input);
else if (buffer_input)
copy_request(argv[0], cld.in);
else
close(0);
if (finish_command(&cld))
exit(1);
}
static int show_text_ref(const char *name, const struct object_id *oid,
int flag, void *cb_data)
{
const char *name_nons = strip_namespace(name);
struct strbuf *buf = cb_data;
struct object *o = parse_object(oid->hash);
if (!o)
return 0;
strbuf_addf(buf, "%s\t%s\n", oid_to_hex(oid), name_nons);
if (o->type == OBJ_TAG) {
o = deref_tag(o, name, 0);
if (!o)
return 0;
strbuf_addf(buf, "%s\t%s^{}\n", sha1_to_hex(o->sha1),
name_nons);
}
return 0;
}
static void get_info_refs(char *arg)
{
const char *service_name = get_parameter("service");
struct strbuf buf = STRBUF_INIT;
hdr_nocache();
if (service_name) {
const char *argv[] = {NULL /* service name */,
"--stateless-rpc", "--advertise-refs",
".", NULL};
struct rpc_service *svc = select_service(service_name);
strbuf_addf(&buf, "application/x-git-%s-advertisement",
svc->name);
hdr_str(content_type, buf.buf);
end_headers();
packet_write(1, "# service=git-%s\n", svc->name);
packet_flush(1);
argv[0] = svc->name;
run_service(argv, 0);
} else {
select_getanyfile();
for_each_namespaced_ref(show_text_ref, &buf);
send_strbuf("text/plain", &buf);
}
strbuf_release(&buf);
}
static int show_head_ref(const char *refname, const struct object_id *oid,
int flag, void *cb_data)
{
struct strbuf *buf = cb_data;
if (flag & REF_ISSYMREF) {
struct object_id unused;
const char *target = resolve_ref_unsafe(refname,
RESOLVE_REF_READING,
unused.hash, NULL);
const char *target_nons = strip_namespace(target);
strbuf_addf(buf, "ref: %s\n", target_nons);
} else {
strbuf_addf(buf, "%s\n", oid_to_hex(oid));
}
return 0;
}
static void get_head(char *arg)
{
struct strbuf buf = STRBUF_INIT;
select_getanyfile();
head_ref_namespaced(show_head_ref, &buf);
send_strbuf("text/plain", &buf);
strbuf_release(&buf);
}
static void get_info_packs(char *arg)
{
size_t objdirlen = strlen(get_object_directory());
struct strbuf buf = STRBUF_INIT;
struct packed_git *p;
size_t cnt = 0;
select_getanyfile();
prepare_packed_git();
for (p = packed_git; p; p = p->next) {
if (p->pack_local)
cnt++;
}
strbuf_grow(&buf, cnt * 53 + 2);
for (p = packed_git; p; p = p->next) {
if (p->pack_local)
strbuf_addf(&buf, "P %s\n", p->pack_name + objdirlen + 6);
}
strbuf_addch(&buf, '\n');
hdr_nocache();
send_strbuf("text/plain; charset=utf-8", &buf);
strbuf_release(&buf);
}
static void check_content_type(const char *accepted_type)
{
const char *actual_type = getenv("CONTENT_TYPE");
if (!actual_type)
actual_type = "";
if (strcmp(actual_type, accepted_type)) {
http_status(415, "Unsupported Media Type");
hdr_nocache();
end_headers();
format_write(1,
"Expected POST with Content-Type '%s',"
" but received '%s' instead.\n",
accepted_type, actual_type);
exit(0);
}
}
static void service_rpc(char *service_name)
{
const char *argv[] = {NULL, "--stateless-rpc", ".", NULL};
struct rpc_service *svc = select_service(service_name);
struct strbuf buf = STRBUF_INIT;
strbuf_reset(&buf);
strbuf_addf(&buf, "application/x-git-%s-request", svc->name);
check_content_type(buf.buf);
hdr_nocache();
strbuf_reset(&buf);
strbuf_addf(&buf, "application/x-git-%s-result", svc->name);
hdr_str(content_type, buf.buf);
end_headers();
argv[0] = svc->name;
run_service(argv, svc->buffer_input);
strbuf_release(&buf);
}
static int dead;
static NORETURN void die_webcgi(const char *err, va_list params)
{
if (dead <= 1) {
vreportf("fatal: ", err, params);
http_status(500, "Internal Server Error");
hdr_nocache();
end_headers();
}
exit(0); /* we successfully reported a failure ;-) */
}
static int die_webcgi_recursing(void)
{
return dead++ > 1;
}
static char* getdir(void)
{
struct strbuf buf = STRBUF_INIT;
char *pathinfo = getenv("PATH_INFO");
char *root = getenv("GIT_PROJECT_ROOT");
char *path = getenv("PATH_TRANSLATED");
if (root && *root) {
if (!pathinfo || !*pathinfo)
die("GIT_PROJECT_ROOT is set but PATH_INFO is not");
if (daemon_avoid_alias(pathinfo))
die("'%s': aliased", pathinfo);
end_url_with_slash(&buf, root);
if (pathinfo[0] == '/')
pathinfo++;
strbuf_addstr(&buf, pathinfo);
return strbuf_detach(&buf, NULL);
} else if (path && *path) {
return xstrdup(path);
} else
die("No GIT_PROJECT_ROOT or PATH_TRANSLATED from server");
return NULL;
}
static struct service_cmd {
const char *method;
const char *pattern;
void (*imp)(char *);
} services[] = {
{"GET", "/HEAD$", get_head},
{"GET", "/info/refs$", get_info_refs},
{"GET", "/objects/info/alternates$", get_text_file},
{"GET", "/objects/info/http-alternates$", get_text_file},
{"GET", "/objects/info/packs$", get_info_packs},
{"GET", "/objects/[0-9a-f]{2}/[0-9a-f]{38}$", get_loose_object},
{"GET", "/objects/pack/pack-[0-9a-f]{40}\\.pack$", get_pack_file},
{"GET", "/objects/pack/pack-[0-9a-f]{40}\\.idx$", get_idx_file},
{"POST", "/git-upload-pack$", service_rpc},
{"POST", "/git-receive-pack$", service_rpc}
};
int main(int argc, char **argv)
{
char *method = getenv("REQUEST_METHOD");
char *dir;
struct service_cmd *cmd = NULL;
char *cmd_arg = NULL;
int i;
git_setup_gettext();
git_extract_argv0_path(argv[0]);
set_die_routine(die_webcgi);
set_die_is_recursing_routine(die_webcgi_recursing);
if (!method)
die("No REQUEST_METHOD from server");
if (!strcmp(method, "HEAD"))
method = "GET";
dir = getdir();
for (i = 0; i < ARRAY_SIZE(services); i++) {
struct service_cmd *c = &services[i];
regex_t re;
regmatch_t out[1];
if (regcomp(&re, c->pattern, REG_EXTENDED))
die("Bogus regex in service table: %s", c->pattern);
if (!regexec(&re, dir, 1, out, 0)) {
size_t n;
if (strcmp(method, c->method)) {
const char *proto = getenv("SERVER_PROTOCOL");
if (proto && !strcmp(proto, "HTTP/1.1")) {
http_status(405, "Method Not Allowed");
hdr_str("Allow", !strcmp(c->method, "GET") ?
"GET, HEAD" : c->method);
} else
http_status(400, "Bad Request");
hdr_nocache();
end_headers();
return 0;
}
cmd = c;
n = out[0].rm_eo - out[0].rm_so;
cmd_arg = xmemdupz(dir + out[0].rm_so + 1, n - 1);
dir[out[0].rm_so] = 0;
break;
}
regfree(&re);
}
if (!cmd)
not_found("Request not supported: '%s'", dir);
setup_path();
if (!enter_repo(dir, 0))
not_found("Not a git repository: '%s'", dir);
if (!getenv("GIT_HTTP_EXPORT_ALL") &&
access("git-daemon-export-ok", F_OK) )
not_found("Repository not exported: '%s'", dir);
http_config();
max_request_buffer = git_env_ulong("GIT_HTTP_MAX_REQUEST_BUFFER",
max_request_buffer);
cmd->imp(cmd_arg);
return 0;
}