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From f065b88b17bd569dda412b2e6f34d921f7badb79 Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= <zbyszek@in.waw.pl>
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Date: Fri, 13 Mar 2015 21:22:05 -0500
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Subject: [PATCH] sd-daemon: simplify sd_pid_notify_with_fds
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Coverity was complaining that CMSG_NXTHDR is used without
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checking the return value. In this case it cannot fail, but
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it is a good excuse to simplify the function a bit.
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CID #1261726.
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(cherry picked from commit 64144440a5d2d94482f882b992fd2a4e0dca7a05)
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http://lists.freedesktop.org/archives/systemd-devel/2015-April/031348.html
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Cherry-picked from: c1258d6
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Resolves: #1222517
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---
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 src/libsystemd/sd-daemon/sd-daemon.c | 61 ++++++++++++++++--------------------
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 1 file changed, 27 insertions(+), 34 deletions(-)
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diff --git a/src/libsystemd/sd-daemon/sd-daemon.c b/src/libsystemd/sd-daemon/sd-daemon.c
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index 22a3a53..1474321 100644
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--- a/src/libsystemd/sd-daemon/sd-daemon.c
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+++ b/src/libsystemd/sd-daemon/sd-daemon.c
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@@ -352,12 +352,10 @@ _public_ int sd_pid_notify_with_fds(pid_t pid, int unset_environment, const char
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                 .msg_iovlen = 1,
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                 .msg_name = &sockaddr,
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         };
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-        struct cmsghdr *control;
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         _cleanup_close_ int fd = -1;
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         struct cmsghdr *cmsg = NULL;
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         const char *e;
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-        size_t controllen_without_ucred = 0;
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-        bool try_without_ucred = false;
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+        bool have_pid;
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         int r;
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         if (!state) {
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@@ -396,42 +394,37 @@ _public_ int sd_pid_notify_with_fds(pid_t pid, int unset_environment, const char
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         if (msghdr.msg_namelen > sizeof(struct sockaddr_un))
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                 msghdr.msg_namelen = sizeof(struct sockaddr_un);
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-        control = alloca(CMSG_SPACE(sizeof(struct ucred)) + CMSG_SPACE(sizeof(int) * n_fds));
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+        have_pid = pid != 0 && pid != getpid();
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-        if (n_fds > 0) {
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-                msghdr.msg_control = control;
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-                msghdr.msg_controllen = CMSG_LEN(sizeof(int) * n_fds);
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+        if (n_fds > 0 || have_pid) {
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+                msghdr.msg_controllen = CMSG_SPACE(sizeof(int) * n_fds) +
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+                                        CMSG_SPACE(sizeof(struct ucred) * have_pid);
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+                msghdr.msg_control = alloca(msghdr.msg_controllen);
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                 cmsg = CMSG_FIRSTHDR(&msghdr);
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-                cmsg->cmsg_level = SOL_SOCKET;
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-                cmsg->cmsg_type = SCM_RIGHTS;
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-                cmsg->cmsg_len = CMSG_LEN(sizeof(int) * n_fds);
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+                if (n_fds > 0) {
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+                        cmsg->cmsg_level = SOL_SOCKET;
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+                        cmsg->cmsg_type = SCM_RIGHTS;
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+                        cmsg->cmsg_len = CMSG_LEN(sizeof(int) * n_fds);
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-                memcpy(CMSG_DATA(cmsg), fds, sizeof(int) * n_fds);
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-        }
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-
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-        if (pid != 0 && pid != getpid()) {
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-                struct ucred *ucred;
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-
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-                try_without_ucred = true;
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-                controllen_without_ucred = msghdr.msg_controllen;
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+                        memcpy(CMSG_DATA(cmsg), fds, sizeof(int) * n_fds);
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-                msghdr.msg_control = control;
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-                msghdr.msg_controllen += CMSG_LEN(sizeof(struct ucred));
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+                        if (have_pid)
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+                                assert_se(cmsg = CMSG_NXTHDR(&msghdr, cmsg));
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+                }
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-                if (cmsg)
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-                        cmsg = CMSG_NXTHDR(&msghdr, cmsg);
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-                else
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-                        cmsg = CMSG_FIRSTHDR(&msghdr);
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+                if (have_pid) {
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+                        struct ucred *ucred;
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-                cmsg->cmsg_level = SOL_SOCKET;
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-                cmsg->cmsg_type = SCM_CREDENTIALS;
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-                cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));
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+                        cmsg->cmsg_level = SOL_SOCKET;
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+                        cmsg->cmsg_type = SCM_CREDENTIALS;
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+                        cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));
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-                ucred = (struct ucred*) CMSG_DATA(cmsg);
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-                ucred->pid = pid;
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-                ucred->uid = getuid();
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-                ucred->gid = getgid();
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+                        ucred = (struct ucred*) CMSG_DATA(cmsg);
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+                        ucred->pid = pid;
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+                        ucred->uid = getuid();
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+                        ucred->gid = getgid();
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+                }
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         }
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         /* First try with fake ucred data, as requested */
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@@ -441,10 +434,10 @@ _public_ int sd_pid_notify_with_fds(pid_t pid, int unset_environment, const char
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         }
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         /* If that failed, try with our own ucred instead */
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-        if (try_without_ucred) {
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-                if (controllen_without_ucred <= 0)
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+        if (have_pid) {
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+                msghdr.msg_controllen -= CMSG_SPACE(sizeof(struct ucred));
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+                if (msghdr.msg_controllen == 0)
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                         msghdr.msg_control = NULL;
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-                msghdr.msg_controllen = controllen_without_ucred;
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                 if (sendmsg(fd, &msghdr, MSG_NOSIGNAL) >= 0) {
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                         r = 1;