Attachment 760 Details for Bug 968 – Use temporary file for prng_seed

[patch] Use temporary file for prng_seed

rand-mkstemp.diff (text/plain), 2.18 KB, created by Damien Miller on 2005-01-08 09:39:32 AEDT

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Creator: Damien Miller

Created: 2005-01-08 09:39:32 AEDT

Size: 2.18 KB

patch

obsolete

>Index: ssh-rand-helper.c
>===================================================================
>RCS file: /var/cvs/openssh/ssh-rand-helper.c,v
>retrieving revision 1.20
>diff -u -r1.20 ssh-rand-helper.c
>--- ssh-rand-helper.c	20 Dec 2004 01:05:08 -0000	1.20
>+++ ssh-rand-helper.c	7 Jan 2005 22:34:10 -0000
>@@ -550,10 +550,11 @@
> void
> prng_write_seedfile(void)
> {
>-	int fd;
>+	int fd, save_errno;
> 	unsigned char seed[SEED_FILE_SIZE];
>-	char filename[MAXPATHLEN];
>+	char filename[MAXPATHLEN], tmpseed[MAXPATHLEN];
> 	struct passwd *pw;
>+	mode_t old_umask;
> 
> 	pw = getpwuid(getuid());
> 	if (pw == NULL)
>@@ -568,7 +569,10 @@
> 	snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir,
> 	    SSH_PRNG_SEED_FILE);
> 
>-	debug("writing PRNG seed to file %.100s", filename);
>+	strlcpy(tmpseed, filename, sizeof(tmpseed));
>+	if (strlcat(tmpseed, ".XXXXXXXXXX", sizeof(tmpseed)) >=
>+	    sizeof(tmpseed))
>+		fatal("PRNG seed filename too long");
> 
> 	if (RAND_bytes(seed, sizeof(seed)) <= 0)
> 		fatal("PRNG seed extraction failed");
>@@ -576,15 +580,31 @@
> 	/* Don't care if the seed doesn't exist */
> 	prng_check_seedfile(filename);
> 
>-	if ((fd = open(filename, O_WRONLY|O_TRUNC|O_CREAT, 0600)) == -1) {
>-		debug("WARNING: couldn't access PRNG seedfile %.100s "
>-		    "(%.100s)", filename, strerror(errno));
>+	old_umask = umask(0177);
>+
>+	if ((fd = mkstemp(tmpseed)) == -1) {
>+		debug("WARNING: couldn't make temporary PRNG seedfile %.100s "
>+		    "(%.100s)", tmpseed, strerror(errno));
> 	} else {
>-		if (atomicio(vwrite, fd, &seed, sizeof(seed)) < sizeof(seed))
>+		debug("writing PRNG seed to file %.100s", tmpseed);
>+		if (atomicio(vwrite, fd, &seed, sizeof(seed)) < sizeof(seed)) {
>+			save_errno = errno;
>+			close(fd);
>+			unlink(tmpseed);
> 			fatal("problem writing PRNG seedfile %.100s "
>-			    "(%.100s)", filename, strerror(errno));
>+			    "(%.100s)", filename, strerror(save_errno));
>+		}
> 		close(fd);
>+		debug("moving temporary PRNG seed to file %.100s", filename);
>+		if (rename(tmpseed, filename) == -1) {
>+			save_errno = errno;
>+			unlink(tmpseed);
>+			fatal("problem renaming PRNG seedfile from %.100s "
>+			    "to %.100s (%.100s)", tmpseed, filename, 
>+			    strerror(save_errno));
>+		}
> 	}
>+	umask(old_umask);
> }
> 
> void

Flags:

dtucker: ok+

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