From ed66f51061f2ce4d31838739c51f11276f97aaaf Mon Sep 17 00:00:00 2001

From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= <zbyszek@in.waw.pl>

Date: Fri, 13 Mar 2015 21:22:05 -0500

Subject: [PATCH] sd-daemon: simplify sd_pid_notify_with_fds

Coverity was complaining that CMSG_NXTHDR is used without

checking the return value. In this case it cannot fail, but

it is a good excuse to simplify the function a bit.

CID #1261726.

(cherry picked from commit 64144440a5d2d94482f882b992fd2a4e0dca7a05)

http://lists.freedesktop.org/archives/systemd-devel/2015-April/031348.html

---

 src/libsystemd/sd-daemon/sd-daemon.c | 61 ++++++++++++++++--------------------

 1 file changed, 27 insertions(+), 34 deletions(-)

diff --git a/src/libsystemd/sd-daemon/sd-daemon.c b/src/libsystemd/sd-daemon/sd-daemon.c

index 22a3a5347a..1474321c95 100644

--- a/src/libsystemd/sd-daemon/sd-daemon.c

+++ b/src/libsystemd/sd-daemon/sd-daemon.c

@@ -352,12 +352,10 @@ _public_ int sd_pid_notify_with_fds(pid_t pid, int unset_environment, const char

                 .msg_iovlen = 1,

                 .msg_name = &sockaddr,

         };

-        struct cmsghdr *control;

         _cleanup_close_ int fd = -1;

         struct cmsghdr *cmsg = NULL;

         const char *e;

-        size_t controllen_without_ucred = 0;

-        bool try_without_ucred = false;

+        bool have_pid;

         int r;

         if (!state) {

@@ -396,42 +394,37 @@ _public_ int sd_pid_notify_with_fds(pid_t pid, int unset_environment, const char

         if (msghdr.msg_namelen > sizeof(struct sockaddr_un))

                 msghdr.msg_namelen = sizeof(struct sockaddr_un);

-        control = alloca(CMSG_SPACE(sizeof(struct ucred)) + CMSG_SPACE(sizeof(int) * n_fds));

+        have_pid = pid != 0 && pid != getpid();

-        if (n_fds > 0) {

-                msghdr.msg_control = control;

-                msghdr.msg_controllen = CMSG_LEN(sizeof(int) * n_fds);

+        if (n_fds > 0 || have_pid) {

+                msghdr.msg_controllen = CMSG_SPACE(sizeof(int) * n_fds) +

+                                        CMSG_SPACE(sizeof(struct ucred) * have_pid);

+                msghdr.msg_control = alloca(msghdr.msg_controllen);

                 cmsg = CMSG_FIRSTHDR(&msghdr);

-                cmsg->cmsg_level = SOL_SOCKET;

-                cmsg->cmsg_type = SCM_RIGHTS;

-                cmsg->cmsg_len = CMSG_LEN(sizeof(int) * n_fds);

+                if (n_fds > 0) {

+                        cmsg->cmsg_level = SOL_SOCKET;

+                        cmsg->cmsg_type = SCM_RIGHTS;

+                        cmsg->cmsg_len = CMSG_LEN(sizeof(int) * n_fds);

-                memcpy(CMSG_DATA(cmsg), fds, sizeof(int) * n_fds);

-        }

-

-        if (pid != 0 && pid != getpid()) {

-                struct ucred *ucred;

-

-                try_without_ucred = true;

-                controllen_without_ucred = msghdr.msg_controllen;

+                        memcpy(CMSG_DATA(cmsg), fds, sizeof(int) * n_fds);

-                msghdr.msg_control = control;

-                msghdr.msg_controllen += CMSG_LEN(sizeof(struct ucred));

+                        if (have_pid)

+                                assert_se(cmsg = CMSG_NXTHDR(&msghdr, cmsg));

+                }

-                if (cmsg)

-                        cmsg = CMSG_NXTHDR(&msghdr, cmsg);

-                else

-                        cmsg = CMSG_FIRSTHDR(&msghdr);

+                if (have_pid) {

+                        struct ucred *ucred;

-                cmsg->cmsg_level = SOL_SOCKET;

-                cmsg->cmsg_type = SCM_CREDENTIALS;

-                cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));

+                        cmsg->cmsg_level = SOL_SOCKET;

+                        cmsg->cmsg_type = SCM_CREDENTIALS;

+                        cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));

-                ucred = (struct ucred*) CMSG_DATA(cmsg);

-                ucred->pid = pid;

-                ucred->uid = getuid();

-                ucred->gid = getgid();

+                        ucred = (struct ucred*) CMSG_DATA(cmsg);

+                        ucred->pid = pid;

+                        ucred->uid = getuid();

+                        ucred->gid = getgid();

+                }

         }

         /* First try with fake ucred data, as requested */

@@ -441,10 +434,10 @@ _public_ int sd_pid_notify_with_fds(pid_t pid, int unset_environment, const char

         }

         /* If that failed, try with our own ucred instead */

-        if (try_without_ucred) {

-                if (controllen_without_ucred <= 0)

+        if (have_pid) {

+                msghdr.msg_controllen -= CMSG_SPACE(sizeof(struct ucred));

+                if (msghdr.msg_controllen == 0)

                         msghdr.msg_control = NULL;

-                msghdr.msg_controllen = controllen_without_ucred;

                 if (sendmsg(fd, &msghdr, MSG_NOSIGNAL) >= 0) {

                         r = 1;