[PATCH v2 12/14] unix-socket: add no-chdir option to unix_stream_listen()
flat view
STALE2042d
SUPERSEDED
From: Jeff Hostetler via GitGitGadget <hidden>
Date: 2021-02-01 19:49:45
Subsystem:
the rest · Maintainer:
Linus Torvalds
Revision v2 of 6 in this series.
Revisions (6)
From: Jeff Hostetler <redacted> Calls to `chdir()` are dangerous in a multi-threaded context. If `unix_stream_listen()` is given a socket pathname that is too big 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. Add `disallow_chdir` flag to `struct unix_sockaddr_context` and change all callers to pass an initialized context structure. Teach `unix_sockaddr_init()` to not allow calls to `chdir()` when flag is set. Signed-off-by: Jeff Hostetler <redacted> --- unix-socket.c | 19 ++++++++++++++++--- unix-socket.h | 2 ++ 2 files changed, 18 insertions(+), 3 deletions(-)
diff --git a/unix-socket.c b/unix-socket.c
index 8bcef18ea55..9726992f276 100644
--- a/unix-socket.c
+++ b/unix-socket.c@@ -11,8 +11,15 @@ static int chdir_len(const char *orig, int len) struct unix_sockaddr_context { char *orig_dir; + unsigned int disallow_chdir:1; }; +#define UNIX_SOCKADDR_CONTEXT_INIT \ +{ \ + .orig_dir=NULL, \ + .disallow_chdir=0, \ +} + static void unix_sockaddr_cleanup(struct unix_sockaddr_context *ctx) { if (!ctx->orig_dir)
@@ -32,7 +39,11 @@ static int unix_sockaddr_init(struct sockaddr_un *sa, const char *path, { int size = strlen(path) + 1; - ctx->orig_dir = NULL; + if (ctx->disallow_chdir && size > sizeof(sa->sun_path)) { + errno = ENAMETOOLONG; + return -1; + } + if (size > sizeof(sa->sun_path)) { const char *slash = find_last_dir_sep(path); const char *dir;
@@ -67,7 +78,7 @@ int unix_stream_connect(const char *path) { int fd, saved_errno; struct sockaddr_un sa; - struct unix_sockaddr_context ctx; + struct unix_sockaddr_context ctx = UNIX_SOCKADDR_CONTEXT_INIT; if (unix_sockaddr_init(&sa, path, &ctx) < 0) return -1;
@@ -96,7 +107,9 @@ int unix_stream_listen(const char *path, int bind_successful = 0; int backlog; struct sockaddr_un sa; - struct unix_sockaddr_context ctx; + struct unix_sockaddr_context ctx = UNIX_SOCKADDR_CONTEXT_INIT; + + ctx.disallow_chdir = opts->disallow_chdir; if (unix_sockaddr_init(&sa, path, &ctx) < 0) return -1;
diff --git a/unix-socket.h b/unix-socket.h
index c28372ef48e..5b0e8ccef10 100644
--- a/unix-socket.h
+++ b/unix-socket.h@@ -4,12 +4,14 @@ struct unix_stream_listen_opts { int listen_backlog_size; unsigned int force_unlink_before_bind:1; + unsigned int disallow_chdir:1; }; #define UNIX_STREAM_LISTEN_OPTS_INIT \ { \ .listen_backlog_size = 5, \ .force_unlink_before_bind = 1, \ + .disallow_chdir = 0, \ } int unix_stream_connect(const char *path);
--
gitgitgadget