[PATCH v5 09/12] unix-socket: disallow chdir() when creating unix domain sockets
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From: Jeff Hostetler via GitGitGadget <hidden>
Date: 2021-03-09 15:03:54
Subsystem:
the rest · Maintainer:
Linus Torvalds
Revision v5 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()` 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 <redacted> --- builtin/credential-cache.c | 2 +- unix-socket.c | 17 ++++++++++++----- unix-socket.h | 3 ++- 3 files changed, 15 insertions(+), 7 deletions(-)
diff --git a/builtin/credential-cache.c b/builtin/credential-cache.c
index 9b3f70990597..76a6ba37223f 100644
--- a/builtin/credential-cache.c
+++ b/builtin/credential-cache.c@@ -14,7 +14,7 @@ static int send_request(const char *socket, const struct strbuf *out) { int got_data = 0; - int fd = unix_stream_connect(socket); + int fd = unix_stream_connect(socket, 0); if (fd < 0) return -1;
diff --git a/unix-socket.c b/unix-socket.c
index 012becd93d57..e0be1badb58d 100644
--- a/unix-socket.c
+++ b/unix-socket.c@@ -30,16 +30,23 @@ static void unix_sockaddr_cleanup(struct unix_sockaddr_context *ctx) } static int unix_sockaddr_init(struct sockaddr_un *sa, const char *path, - struct unix_sockaddr_context *ctx) + struct unix_sockaddr_context *ctx, + int disallow_chdir) { int size = strlen(path) + 1; ctx->orig_dir = NULL; if (size > sizeof(sa->sun_path)) { - const char *slash = find_last_dir_sep(path); + const char *slash; const char *dir; struct strbuf cwd = STRBUF_INIT; + if (disallow_chdir) { + errno = ENAMETOOLONG; + return -1; + } + + slash = find_last_dir_sep(path); if (!slash) { errno = ENAMETOOLONG; return -1;
@@ -65,13 +72,13 @@ static int unix_sockaddr_init(struct sockaddr_un *sa, const char *path, return 0; } -int unix_stream_connect(const char *path) +int unix_stream_connect(const char *path, int disallow_chdir) { int fd = -1, saved_errno; struct sockaddr_un sa; struct unix_sockaddr_context ctx; - if (unix_sockaddr_init(&sa, path, &ctx) < 0) + if (unix_sockaddr_init(&sa, path, &ctx, disallow_chdir) < 0) return -1; fd = socket(AF_UNIX, SOCK_STREAM, 0); if (fd < 0)
@@ -101,7 +108,7 @@ int unix_stream_listen(const char *path, unlink(path); - if (unix_sockaddr_init(&sa, path, &ctx) < 0) + if (unix_sockaddr_init(&sa, path, &ctx, opts->disallow_chdir) < 0) return -1; fd = socket(AF_UNIX, SOCK_STREAM, 0); if (fd < 0)
diff --git a/unix-socket.h b/unix-socket.h
index ec2fb3ea7267..8542cdd7995d 100644
--- a/unix-socket.h
+++ b/unix-socket.h@@ -3,11 +3,12 @@ struct unix_stream_listen_opts { int listen_backlog_size; + unsigned int disallow_chdir:1; }; #define UNIX_STREAM_LISTEN_OPTS_INIT { 0 } -int unix_stream_connect(const char *path); +int unix_stream_connect(const char *path, int disallow_chdir); int unix_stream_listen(const char *path, const struct unix_stream_listen_opts *opts);
--
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