daandemeyer / rpms / systemd

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From d06dfdde758e178d1ae20756890302a5c265ac08 Mon Sep 17 00:00:00 2001
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From: Lennart Poettering <lennart@poettering.net>
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Date: Fri, 5 Jan 2018 13:24:58 +0100
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Subject: [PATCH] sd-dameon: also sent ucred when our UID differs from EUID
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Let's be explicit, and always send the messages from our UID and never
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our EUID. Previously this behaviour was conditionalized only on whether
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the PID was specified, which made this non-obvious.
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(cherry picked from commit 9e1d021ee3f147486c5cfac69b3cbf6f4b36eb79)
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Related: #1663143
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---
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 src/libsystemd/sd-daemon/sd-daemon.c | 39 +++++++++++++++++++---------
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 1 file changed, 27 insertions(+), 12 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 2c4dd9d225..82483a38e6 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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@@ -40,6 +40,8 @@
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 #include "socket-util.h"
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 #include "sd-daemon.h"
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+#define SNDBUF_SIZE (8*1024*1024)
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+
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 _public_ int sd_listen_fds(int unset_environment) {
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         const char *e;
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         unsigned n;
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@@ -340,7 +342,13 @@ _public_ int sd_is_mq(int fd, const char *path) {
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         return 1;
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 }
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-_public_ int sd_pid_notify_with_fds(pid_t pid, int unset_environment, const char *state, const int *fds, unsigned n_fds) {
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+_public_ int sd_pid_notify_with_fds(
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+                pid_t pid,
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+                int unset_environment,
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+                const char *state,
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+                const int *fds,
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+                unsigned n_fds) {
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+
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         union sockaddr_union sockaddr = {
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                 .sa.sa_family = AF_UNIX,
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         };
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@@ -355,7 +363,7 @@ _public_ int sd_pid_notify_with_fds(pid_t pid, int unset_environment, const char
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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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-        bool have_pid;
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+        bool send_ucred;
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         int r;
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         if (!state) {
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@@ -384,6 +392,8 @@ _public_ int sd_pid_notify_with_fds(pid_t pid, int unset_environment, const char
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                 goto finish;
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         }
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+        (void) fd_inc_sndbuf(fd, SNDBUF_SIZE);
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+
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         iovec.iov_len = strlen(state);
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         strncpy(sockaddr.un.sun_path, e, sizeof(sockaddr.un.sun_path));
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@@ -394,13 +404,18 @@ _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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-        have_pid = pid != 0 && pid != getpid();
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+        send_ucred =
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+                (pid != 0 && pid != getpid()) ||
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+                getuid() != geteuid() ||
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+                getgid() != getegid();
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+
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+        if (n_fds > 0 || send_ucred) {
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+                /* CMSG_SPACE(0) may return value different than zero, which results in miscalculated controllen. */
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+                msghdr.msg_controllen =
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+                        (n_fds > 0 ? CMSG_SPACE(sizeof(int) * n_fds) : 0) +
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+                        (send_ucred ? CMSG_SPACE(sizeof(struct ucred)) : 0);
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-        if (n_fds > 0 || have_pid) {
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-                /* CMSG_SPACE(0) may return value different then zero, which results in miscalculated controllen. */
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-                msghdr.msg_controllen = (n_fds ? CMSG_SPACE(sizeof(int) * n_fds) : 0) +
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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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+                msghdr.msg_control = alloca0(msghdr.msg_controllen);
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                 cmsg = CMSG_FIRSTHDR(&msghdr);
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                 if (n_fds > 0) {
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@@ -410,11 +425,11 @@ _public_ int sd_pid_notify_with_fds(pid_t pid, int unset_environment, const char
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                         memcpy(CMSG_DATA(cmsg), fds, sizeof(int) * n_fds);
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-                        if (have_pid)
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+                        if (send_ucred)
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                                 assert_se(cmsg = CMSG_NXTHDR(&msghdr, cmsg));
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                 }
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-                if (have_pid) {
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+                if (send_ucred) {
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                         struct ucred *ucred;
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                         cmsg->cmsg_level = SOL_SOCKET;
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@@ -422,7 +437,7 @@ _public_ int sd_pid_notify_with_fds(pid_t pid, int unset_environment, const char
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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->pid = pid != 0 ? pid : getpid();
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                         ucred->uid = getuid();
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                         ucred->gid = getgid();
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                 }
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@@ -435,7 +450,7 @@ _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 (have_pid) {
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+        if (send_ucred) {
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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;