aboutsummaryrefslogtreecommitdiffstats
path: root/net
diff options
context:
space:
mode:
authorUlrich Drepper <drepper@redhat.com>2007-07-16 02:40:34 -0400
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-07-16 12:05:45 -0400
commit4a19542e5f694cd408a32c3d9dc593ba9366e2d7 (patch)
tree12f5fd603b516b4e24ec4850d5589273d24be569 /net
parentf23513e8d96cf5e6cf8d2ff0cb5dd6bbc33995e4 (diff)
O_CLOEXEC for SCM_RIGHTS
Part two in the O_CLOEXEC saga: adding support for file descriptors received through Unix domain sockets. The patch is once again pretty minimal, it introduces a new flag for recvmsg and passes it just like the existing MSG_CMSG_COMPAT flag. I think this bit is not used otherwise but the networking people will know better. This new flag is not recognized by recvfrom and recv. These functions cannot be used for that purpose and the asymmetry this introduces is not worse than the already existing MSG_CMSG_COMPAT situations. The patch must be applied on the patch which introduced O_CLOEXEC. It has to remove static from the new get_unused_fd_flags function but since scm.c cannot live in a module the function still hasn't to be exported. Here's a test program to make sure the code works. It's so much longer than the actual patch... #include <errno.h> #include <error.h> #include <fcntl.h> #include <stdio.h> #include <string.h> #include <unistd.h> #include <sys/socket.h> #include <sys/un.h> #ifndef O_CLOEXEC # define O_CLOEXEC 02000000 #endif #ifndef MSG_CMSG_CLOEXEC # define MSG_CMSG_CLOEXEC 0x40000000 #endif int main (int argc, char *argv[]) { if (argc > 1) { int fd = atol (argv[1]); printf ("child: fd = %d\n", fd); if (fcntl (fd, F_GETFD) == 0 || errno != EBADF) { puts ("file descriptor valid in child"); return 1; } return 0; } struct sockaddr_un sun; strcpy (sun.sun_path, "./testsocket"); sun.sun_family = AF_UNIX; char databuf[] = "hello"; struct iovec iov[1]; iov[0].iov_base = databuf; iov[0].iov_len = sizeof (databuf); union { struct cmsghdr hdr; char bytes[CMSG_SPACE (sizeof (int))]; } buf; struct msghdr msg = { .msg_iov = iov, .msg_iovlen = 1, .msg_control = buf.bytes, .msg_controllen = sizeof (buf) }; struct cmsghdr *cmsg = CMSG_FIRSTHDR (&msg); cmsg->cmsg_level = SOL_SOCKET; cmsg->cmsg_type = SCM_RIGHTS; cmsg->cmsg_len = CMSG_LEN (sizeof (int)); msg.msg_controllen = cmsg->cmsg_len; pid_t child = fork (); if (child == -1) error (1, errno, "fork"); if (child == 0) { int sock = socket (PF_UNIX, SOCK_STREAM, 0); if (sock < 0) error (1, errno, "socket"); if (bind (sock, (struct sockaddr *) &sun, sizeof (sun)) < 0) error (1, errno, "bind"); if (listen (sock, SOMAXCONN) < 0) error (1, errno, "listen"); int conn = accept (sock, NULL, NULL); if (conn == -1) error (1, errno, "accept"); *(int *) CMSG_DATA (cmsg) = sock; if (sendmsg (conn, &msg, MSG_NOSIGNAL) < 0) error (1, errno, "sendmsg"); return 0; } /* For a test suite this should be more robust like a barrier in shared memory. */ sleep (1); int sock = socket (PF_UNIX, SOCK_STREAM, 0); if (sock < 0) error (1, errno, "socket"); if (connect (sock, (struct sockaddr *) &sun, sizeof (sun)) < 0) error (1, errno, "connect"); unlink (sun.sun_path); *(int *) CMSG_DATA (cmsg) = -1; if (recvmsg (sock, &msg, MSG_CMSG_CLOEXEC) < 0) error (1, errno, "recvmsg"); int fd = *(int *) CMSG_DATA (cmsg); if (fd == -1) error (1, 0, "no descriptor received"); char fdname[20]; snprintf (fdname, sizeof (fdname), "%d", fd); execl ("/proc/self/exe", argv[0], fdname, NULL); puts ("execl failed"); return 1; } [akpm@linux-foundation.org: Fix fastcall inconsistency noted by Michael Buesch] [akpm@linux-foundation.org: build fix] Signed-off-by: Ulrich Drepper <drepper@redhat.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Michael Buesch <mb@bu3sch.de> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Acked-by: David S. Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'net')
-rw-r--r--net/compat.c3
-rw-r--r--net/core/scm.c3
-rw-r--r--net/socket.c4
3 files changed, 5 insertions, 5 deletions
diff --git a/net/compat.c b/net/compat.c
index 9a0f5f2b90c8..d74d82155d78 100644
--- a/net/compat.c
+++ b/net/compat.c
@@ -276,7 +276,8 @@ void scm_detach_fds_compat(struct msghdr *kmsg, struct scm_cookie *scm)
276 err = security_file_receive(fp[i]); 276 err = security_file_receive(fp[i]);
277 if (err) 277 if (err)
278 break; 278 break;
279 err = get_unused_fd(); 279 err = get_unused_fd_flags(MSG_CMSG_CLOEXEC & kmsg->msg_flags
280 ? O_CLOEXEC : 0);
280 if (err < 0) 281 if (err < 0)
281 break; 282 break;
282 new_fd = err; 283 new_fd = err;
diff --git a/net/core/scm.c b/net/core/scm.c
index 292ad8d5ad76..44c4ec2c8769 100644
--- a/net/core/scm.c
+++ b/net/core/scm.c
@@ -228,7 +228,8 @@ void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm)
228 err = security_file_receive(fp[i]); 228 err = security_file_receive(fp[i]);
229 if (err) 229 if (err)
230 break; 230 break;
231 err = get_unused_fd(); 231 err = get_unused_fd_flags(MSG_CMSG_CLOEXEC & msg->msg_flags
232 ? O_CLOEXEC : 0);
232 if (err < 0) 233 if (err < 0)
233 break; 234 break;
234 new_fd = err; 235 new_fd = err;
diff --git a/net/socket.c b/net/socket.c
index f4530196a70a..b71114250046 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -1939,9 +1939,7 @@ asmlinkage long sys_recvmsg(int fd, struct msghdr __user *msg,
1939 total_len = err; 1939 total_len = err;
1940 1940
1941 cmsg_ptr = (unsigned long)msg_sys.msg_control; 1941 cmsg_ptr = (unsigned long)msg_sys.msg_control;
1942 msg_sys.msg_flags = 0; 1942 msg_sys.msg_flags = flags & (MSG_CMSG_CLOEXEC|MSG_CMSG_COMPAT);
1943 if (MSG_CMSG_COMPAT & flags)
1944 msg_sys.msg_flags = MSG_CMSG_COMPAT;
1945 1943
1946 if (sock->file->f_flags & O_NONBLOCK) 1944 if (sock->file->f_flags & O_NONBLOCK)
1947 flags |= MSG_DONTWAIT; 1945 flags |= MSG_DONTWAIT;