A normal request to git-daemon is structured as
"command path/to/repo\0host=..\0" and due to a bug introduced in
49ba83fb6 (Add virtualization support to git-daemon, 2006-09-19) we
aren't able to place any extra arguments (separated by NULs) besides the
host otherwise the parsing of those arguments would enter an infinite
loop. This bug was fixed in 73bb33a94 (daemon: Strictly parse the
"extra arg" part of the command, 2009-06-04) but a check was put in
place to disallow extra arguments so that new clients wouldn't trigger
this bug in older servers.
In order to get around this limitation teach git-daemon to recognize
additional request arguments hidden behind a second NUL byte. Requests
can then be structured like:
"command path/to/repo\0host=..\0\0version=1\0key=value\0". git-daemon
can then parse out the extra arguments and set 'GIT_PROTOCOL'
accordingly.
By placing these extra arguments behind a second NUL byte we can skirt
around both the infinite loop bug in 49ba83fb6 (Add virtualization
support to git-daemon, 2006-09-19) as well as the explicit disallowing
of extra arguments introduced in 73bb33a94 (daemon: Strictly parse the
"extra arg" part of the command, 2009-06-04) because both of these
versions of git-daemon check for a single NUL byte after the host
argument before terminating the argument parsing.
Signed-off-by: Brandon Williams <bmwill@xxxxxxxxxx>
---
daemon.c | 71 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++--------
1 file changed, 62 insertions(+), 9 deletions(-)
diff --git a/daemon.c b/daemon.c
index 30747075f..e37e343d0 100644
--- a/daemon.c
+++ b/daemon.c
@@ -282,7 +282,7 @@ static const char *path_ok(const char *directory, struct hostinfo *hi)
return NULL; /* Fallthrough. Deny by default */
}
-typedef int (*daemon_service_fn)(void);
+typedef int (*daemon_service_fn)(const struct argv_array *env);
struct daemon_service {
const char *name;
const char *config_name;
@@ -363,7 +363,7 @@ static int run_access_hook(struct daemon_service *service, const char *dir,
}
static int run_service(const char *dir, struct daemon_service *service,
- struct hostinfo *hi)
+ struct hostinfo *hi, const struct argv_array *env)
{
const char *path;
int enabled = service->enabled;
@@ -422,7 +422,7 @@ static int run_service(const char *dir, struct daemon_service *service,
*/
signal(SIGTERM, SIG_IGN);
- return service->fn();
+ return service->fn(env);
}
static void copy_to_log(int fd)
@@ -462,25 +462,34 @@ static int run_service_command(struct child_process *cld)
return finish_command(cld);
}
-static int upload_pack(void)
+static int upload_pack(const struct argv_array *env)
{
struct child_process cld = CHILD_PROCESS_INIT;
argv_array_pushl(&cld.args, "upload-pack", "--strict", NULL);
argv_array_pushf(&cld.args, "--timeout=%u", timeout);
+
+ argv_array_pushv(&cld.env_array, env->argv);
+
return run_service_command(&cld);
}
-static int upload_archive(void)
+static int upload_archive(const struct argv_array *env)
{
struct child_process cld = CHILD_PROCESS_INIT;
argv_array_push(&cld.args, "upload-archive");
+
+ argv_array_pushv(&cld.env_array, env->argv);
+
return run_service_command(&cld);
}
-static int receive_pack(void)
+static int receive_pack(const struct argv_array *env)
{
struct child_process cld = CHILD_PROCESS_INIT;
argv_array_push(&cld.args, "receive-pack");
+
+ argv_array_pushv(&cld.env_array, env->argv);
+
return run_service_command(&cld);
}
@@ -573,8 +582,11 @@ static void canonicalize_client(struct strbuf *out, const char *in)
/*
* Read the host as supplied by the client connection.
+ *
+ * Returns a pointer to the character after the NUL byte terminating the host
+ * arguemnt, or 'extra_args' if there is no host arguemnt.
*/
-static void parse_host_arg(struct hostinfo *hi, char *extra_args, int buflen)
+static char *parse_host_arg(struct hostinfo *hi, char *extra_args, int buflen)
{
char *val;
int vallen;
@@ -602,6 +614,43 @@ static void parse_host_arg(struct hostinfo *hi, char *extra_args, int buflen)
if (extra_args < end && *extra_args)
die("Invalid request");
}
+
+ return extra_args;
+}
+
+static void parse_extra_args(struct hostinfo *hi, struct argv_array *env,
+ char *extra_args, int buflen)
+{
+ const char *end = extra_args + buflen;
+ struct strbuf git_protocol = STRBUF_INIT;
+
+ /* First look for the host argument */
+ extra_args = parse_host_arg(hi, extra_args, buflen);
+
+ /* Look for additional arguments places after a second NUL byte */
+ for (; extra_args < end; extra_args += strlen(extra_args) + 1) {
+ const char *arg = extra_args;
+
+ /*
+ * Parse the extra arguments, adding most to 'git_protocol'
+ * which will be used to set the 'GIT_PROTOCOL' envvar in the
+ * service that will be run.
+ *
+ * If there ends up being a particular arg in the future that
+ * git-daemon needs to parse specificly (like the 'host' arg)
+ * then it can be parsed here and not added to 'git_protocol'.
+ */
+ if (*arg) {
+ if (git_protocol.len > 0)
+ strbuf_addch(&git_protocol, ':');
+ strbuf_addstr(&git_protocol, arg);
+ }
+ }
+
+ if (git_protocol.len > 0)
+ argv_array_pushf(env, GIT_PROTOCOL_ENVIRONMENT "=%s",
+ git_protocol.buf);
+ strbuf_release(&git_protocol);
}
/*
@@ -695,6 +744,7 @@ static int execute(void)
int pktlen, len, i;
char *addr = getenv("REMOTE_ADDR"), *port = getenv("REMOTE_PORT");
struct hostinfo hi;
+ struct argv_array env = ARGV_ARRAY_INIT;
hostinfo_init(&hi);
@@ -716,8 +766,9 @@ static int execute(void)
pktlen--;
}
+ /* parse additional args hidden behind a NUL byte */
if (len != pktlen)
- parse_host_arg(&hi, line + len + 1, pktlen - len - 1);
+ parse_extra_args(&hi, &env, line + len + 1, pktlen - len - 1);
for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
struct daemon_service *s = &(daemon_service[i]);
@@ -730,13 +781,15 @@ static int execute(void)
* Note: The directory here is probably context sensitive,
* and might depend on the actual service being performed.
*/
- int rc = run_service(arg, s, &hi);
+ int rc = run_service(arg, s, &hi, &env);
hostinfo_clear(&hi);
+ argv_array_clear(&env);
return rc;
}
}
hostinfo_clear(&hi);
+ argv_array_clear(&env);
logerror("Protocol error: '%s'", line);
return -1;
}
--
2.15.0.rc0.271.g36b669edcc-goog
