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authorJeff King <peff@peff.net>2012-01-09 23:44:30 -0500
committerJunio C Hamano <gitster@pobox.com>2012-01-10 10:10:36 -0800
commit1eb10f4091931d6b89ff10edad63ce9c01ed17fd (patch)
tree6b15f865e2ab04d87c57842f341f7b7d8ec5f00d /unix-socket.c
parent98c2924cfa84a7f30b17636bd5632e53a0fa002e (diff)
downloadgit-1eb10f4091931d6b89ff10edad63ce9c01ed17fd.tar.gz
unix-socket: handle long socket pathnames
On many systems, the sockaddr_un.sun_path field is quite small. Even on Linux, it is only 108 characters. A user of the credential-cache daemon can easily surpass this, especially if their home directory is in a deep directory tree (since the default location expands ~/.git-credentials). We can hack around this in the unix-socket.[ch] code by doing a chdir() to the enclosing directory, feeding the relative basename to the socket functions, and then restoring the working directory. This introduces several new possible error cases for creating a socket, including an irrecoverable one in the case that we can't restore the working directory. In the case of the credential-cache code, we could perhaps get away with simply chdir()-ing to the socket directory and never coming back. However, I'd rather do it at the lower level for a few reasons: 1. It keeps the hackery behind an opaque interface instead of polluting the main program logic. 2. A hack in credential-cache won't help any unix-socket users who come along later. 3. The chdir trickery isn't that likely to fail (basically it's only a problem if your cwd is missing or goes away while you're running). And because we only enable the hack when we get a too-long name, it can only fail in cases that would have failed under the previous code anyway. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'unix-socket.c')
-rw-r--r--unix-socket.c71
1 files changed, 66 insertions, 5 deletions
diff --git a/unix-socket.c b/unix-socket.c
index 84b15099f2..7d8bec6158 100644
--- a/unix-socket.c
+++ b/unix-socket.c
@@ -9,27 +9,83 @@ static int unix_stream_socket(void)
return fd;
}
-static void unix_sockaddr_init(struct sockaddr_un *sa, const char *path)
+static int chdir_len(const char *orig, int len)
+{
+ char *path = xmemdupz(orig, len);
+ int r = chdir(path);
+ free(path);
+ return r;
+}
+
+struct unix_sockaddr_context {
+ char orig_dir[PATH_MAX];
+};
+
+static void unix_sockaddr_cleanup(struct unix_sockaddr_context *ctx)
+{
+ if (!ctx->orig_dir[0])
+ return;
+ /*
+ * If we fail, we can't just return an error, since we have
+ * moved the cwd of the whole process, which could confuse calling
+ * code. We are better off to just die.
+ */
+ if (chdir(ctx->orig_dir) < 0)
+ die("unable to restore original working directory");
+}
+
+static int unix_sockaddr_init(struct sockaddr_un *sa, const char *path,
+ struct unix_sockaddr_context *ctx)
{
int size = strlen(path) + 1;
- if (size > sizeof(sa->sun_path))
- die("socket path is too long to fit in sockaddr");
+
+ ctx->orig_dir[0] = '\0';
+ if (size > sizeof(sa->sun_path)) {
+ const char *slash = find_last_dir_sep(path);
+ const char *dir;
+
+ if (!slash) {
+ errno = ENAMETOOLONG;
+ return -1;
+ }
+
+ dir = path;
+ path = slash + 1;
+ size = strlen(path) + 1;
+ if (size > sizeof(sa->sun_path)) {
+ errno = ENAMETOOLONG;
+ return -1;
+ }
+
+ if (!getcwd(ctx->orig_dir, sizeof(ctx->orig_dir))) {
+ errno = ENAMETOOLONG;
+ return -1;
+ }
+ if (chdir_len(dir, slash - dir) < 0)
+ return -1;
+ }
+
memset(sa, 0, sizeof(*sa));
sa->sun_family = AF_UNIX;
memcpy(sa->sun_path, path, size);
+ return 0;
}
int unix_stream_connect(const char *path)
{
int fd;
struct sockaddr_un sa;
+ struct unix_sockaddr_context ctx;
- unix_sockaddr_init(&sa, path);
+ if (unix_sockaddr_init(&sa, path, &ctx) < 0)
+ return -1;
fd = unix_stream_socket();
if (connect(fd, (struct sockaddr *)&sa, sizeof(sa)) < 0) {
+ unix_sockaddr_cleanup(&ctx);
close(fd);
return -1;
}
+ unix_sockaddr_cleanup(&ctx);
return fd;
}
@@ -37,20 +93,25 @@ int unix_stream_listen(const char *path)
{
int fd;
struct sockaddr_un sa;
+ struct unix_sockaddr_context ctx;
- unix_sockaddr_init(&sa, path);
+ if (unix_sockaddr_init(&sa, path, &ctx) < 0)
+ return -1;
fd = unix_stream_socket();
unlink(path);
if (bind(fd, (struct sockaddr *)&sa, sizeof(sa)) < 0) {
+ unix_sockaddr_cleanup(&ctx);
close(fd);
return -1;
}
if (listen(fd, 5) < 0) {
+ unix_sockaddr_cleanup(&ctx);
close(fd);
return -1;
}
+ unix_sockaddr_cleanup(&ctx);
return fd;
}