55 lines
1.4 KiB
Diff
55 lines
1.4 KiB
Diff
From ad387832979b6ce4c93f64fe706301cd7d034e87 Mon Sep 17 00:00:00 2001
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From: "W.C.A. Wijngaards" <wouter@nlnetlabs.nl>
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Date: Mon, 23 Nov 2020 13:42:11 +0100
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Subject: [PATCH] - Fix for #303 CVE-2020-28935 : Fix that symlink does not
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interfere with chown of pidfile.
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---
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daemon/unbound.c | 26 ++++++++++++++++++++------
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doc/Changelog | 2 ++
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2 files changed, 22 insertions(+), 6 deletions(-)
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diff --git a/daemon/unbound.c b/daemon/unbound.c
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index cd0fd69f2..45537d5c9 100644
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--- a/daemon/unbound.c
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+++ b/daemon/unbound.c
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@@ -341,18 +341,32 @@ readpid (const char* file)
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static void
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writepid (const char* pidfile, pid_t pid)
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{
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- FILE* f;
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+ int fd;
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+ char pidbuf[32];
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+ size_t count = 0;
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+ snprintf(pidbuf, sizeof(pidbuf), "%lu\n", (unsigned long)pid);
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- if ((f = fopen(pidfile, "w")) == NULL ) {
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+ if((fd = open(pidfile, O_WRONLY | O_CREAT | O_TRUNC
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+#ifdef O_NOFOLLOW
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+ | O_NOFOLLOW
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+#endif
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+ , 0644)) == -1) {
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log_err("cannot open pidfile %s: %s",
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pidfile, strerror(errno));
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return;
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}
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- if(fprintf(f, "%lu\n", (unsigned long)pid) < 0) {
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- log_err("cannot write to pidfile %s: %s",
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- pidfile, strerror(errno));
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+ while(count < strlen(pidbuf)) {
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+ ssize_t r = write(fd, pidbuf+count, strlen(pidbuf)-count);
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+ if(r == -1) {
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+ if(errno == EAGAIN || errno == EINTR)
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+ continue;
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+ log_err("cannot write to pidfile %s: %s",
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+ pidfile, strerror(errno));
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+ break;
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+ }
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+ count += r;
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}
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- fclose(f);
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+ close(fd);
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}
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/**
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