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77e522caae
Calls to `chdir()` are dangerous in a multi-threaded context. If `unix_stream_listen()` or `unix_stream_connect()` is given a socket pathname that is too long to fit in a `sockaddr_un` structure, it will `chdir()` to the parent directory of the requested socket pathname, create the socket using a relative pathname, and then `chdir()` back. This is not thread-safe. Teach `unix_sockaddr_init()` to not allow calls to `chdir()` when this flag is set. Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
137 lines
2.7 KiB
C
137 lines
2.7 KiB
C
#include "cache.h"
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#include "unix-socket.h"
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#define DEFAULT_UNIX_STREAM_LISTEN_BACKLOG (5)
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static int chdir_len(const char *orig, int len)
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{
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char *path = xmemdupz(orig, len);
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int r = chdir(path);
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free(path);
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return r;
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}
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struct unix_sockaddr_context {
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char *orig_dir;
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};
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static void unix_sockaddr_cleanup(struct unix_sockaddr_context *ctx)
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{
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if (!ctx->orig_dir)
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return;
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/*
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* If we fail, we can't just return an error, since we have
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* moved the cwd of the whole process, which could confuse calling
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* code. We are better off to just die.
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*/
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if (chdir(ctx->orig_dir) < 0)
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die("unable to restore original working directory");
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free(ctx->orig_dir);
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}
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static int unix_sockaddr_init(struct sockaddr_un *sa, const char *path,
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struct unix_sockaddr_context *ctx,
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int disallow_chdir)
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{
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int size = strlen(path) + 1;
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ctx->orig_dir = NULL;
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if (size > sizeof(sa->sun_path)) {
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const char *slash;
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const char *dir;
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struct strbuf cwd = STRBUF_INIT;
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if (disallow_chdir) {
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errno = ENAMETOOLONG;
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return -1;
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}
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slash = find_last_dir_sep(path);
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if (!slash) {
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errno = ENAMETOOLONG;
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return -1;
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}
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dir = path;
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path = slash + 1;
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size = strlen(path) + 1;
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if (size > sizeof(sa->sun_path)) {
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errno = ENAMETOOLONG;
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return -1;
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}
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if (strbuf_getcwd(&cwd))
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return -1;
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ctx->orig_dir = strbuf_detach(&cwd, NULL);
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if (chdir_len(dir, slash - dir) < 0)
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return -1;
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}
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memset(sa, 0, sizeof(*sa));
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sa->sun_family = AF_UNIX;
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memcpy(sa->sun_path, path, size);
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return 0;
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}
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int unix_stream_connect(const char *path, int disallow_chdir)
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{
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int fd = -1, saved_errno;
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struct sockaddr_un sa;
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struct unix_sockaddr_context ctx;
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if (unix_sockaddr_init(&sa, path, &ctx, disallow_chdir) < 0)
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return -1;
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fd = socket(AF_UNIX, SOCK_STREAM, 0);
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if (fd < 0)
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goto fail;
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if (connect(fd, (struct sockaddr *)&sa, sizeof(sa)) < 0)
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goto fail;
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unix_sockaddr_cleanup(&ctx);
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return fd;
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fail:
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saved_errno = errno;
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if (fd != -1)
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close(fd);
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unix_sockaddr_cleanup(&ctx);
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errno = saved_errno;
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return -1;
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}
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int unix_stream_listen(const char *path,
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const struct unix_stream_listen_opts *opts)
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{
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int fd = -1, saved_errno;
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int backlog;
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struct sockaddr_un sa;
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struct unix_sockaddr_context ctx;
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unlink(path);
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if (unix_sockaddr_init(&sa, path, &ctx, opts->disallow_chdir) < 0)
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return -1;
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fd = socket(AF_UNIX, SOCK_STREAM, 0);
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if (fd < 0)
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goto fail;
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if (bind(fd, (struct sockaddr *)&sa, sizeof(sa)) < 0)
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goto fail;
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backlog = opts->listen_backlog_size;
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if (backlog <= 0)
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backlog = DEFAULT_UNIX_STREAM_LISTEN_BACKLOG;
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if (listen(fd, backlog) < 0)
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goto fail;
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unix_sockaddr_cleanup(&ctx);
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return fd;
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fail:
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saved_errno = errno;
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if (fd != -1)
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close(fd);
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unix_sockaddr_cleanup(&ctx);
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errno = saved_errno;
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return -1;
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}
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