From: Roy Marples <roy@marples.name>
Date: Tue, 21 Jan 2020 20:17:27 +0000 (+0000)
Subject: privsep: Only fetch PRIVSEP_USER at init
X-Git-Tag: v9.0.0~91
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=321a8914cee82c0cb2c7cc7a59c9fd01f16c2d5a;p=thirdparty%2Fdhcpcd.git

privsep: Only fetch PRIVSEP_USER at init

And not each time it's needed - we don't want a sudden change in
the details to affect a running dhcpcd.
---

diff --git a/src/dhcpcd.h b/src/dhcpcd.h
index 1c727660..6242956a 100644
--- a/src/dhcpcd.h
+++ b/src/dhcpcd.h
@@ -121,6 +121,8 @@ TAILQ_HEAD(if_head, interface);
 			CMSG_SPACE(sizeof(int)))
 #endif
 
+struct passwd;
+
 struct dhcpcd_ctx {
 	char pidfile[sizeof(PIDFILE) + IF_NAMESIZE + 1];
 	int fork_fd;	/* FD for the fork init signal pipe */
@@ -182,7 +184,7 @@ struct dhcpcd_ctx {
 	char *randomstate; /* original state */
 
 #ifdef PRIVSEP
-	char *ps_user;		/* Username to drop privs to */
+	struct passwd *ps_user;	/* struct passwd for privsep user */
 	pid_t ps_root_pid;
 	int ps_root_fd;		/* Privileged Actioneer commands */
 	int ps_data_fd;		/* Data from root spawned processes */
diff --git a/src/privsep-root.c b/src/privsep-root.c
index 076d71de..2dc57ae7 100644
--- a/src/privsep-root.c
+++ b/src/privsep-root.c
@@ -203,7 +203,7 @@ ps_root_run_script(struct dhcpcd_ctx *ctx, const void *data, size_t len)
 }
 
 static ssize_t
-ps_root_docopy(const char *dir, const char *file)
+ps_root_docopy(struct dhcpcd_ctx *ctx, const char *file)
 {
 
 	char path[PATH_MAX], buf[BUFSIZ], *slash;
@@ -216,7 +216,8 @@ ps_root_docopy(const char *dir, const char *file)
 	struct timeval ts[2];
 #endif
 
-	if (snprintf(path, sizeof(path), "%s/%s", dir, file) == -1)
+	if (snprintf(path, sizeof(path), "%s/%s",
+	    ctx->ps_user->pw_dir, file) == -1)
 		return -1;
 	if (stat(file, &from_sb) == -1)
 		return -1;
@@ -275,22 +276,7 @@ ps_root_docopy(const char *dir, const char *file)
 }
 
 static ssize_t
-ps_root_docopy1(const char *file)
-{
-	struct passwd *pw;
-
-	errno = 0;
-	if ((pw = getpwnam(PRIVSEP_USER)) == NULL) {
-		if (errno == 0)
-			errno = ENOENT;
-		return -1;
-	}
-
-	return ps_root_docopy(pw->pw_dir, file);
-}
-
-static ssize_t
-ps_root_dofileop(void *data, size_t len, uint8_t op)
+ps_root_dofileop(struct dhcpcd_ctx *ctx, void *data, size_t len, uint8_t op)
 {
 	char *path = data;
 	size_t plen;
@@ -309,7 +295,7 @@ ps_root_dofileop(void *data, size_t len, uint8_t op)
 
 	switch(op) {
 	case PS_COPY:
-		return ps_root_docopy1(path);
+		return ps_root_docopy(ctx, path);
 	case PS_UNLINK:
 		return (ssize_t)unlink(path);
 	default:
@@ -389,7 +375,7 @@ ps_root_recvmsgcb(void *arg, struct ps_msghdr *psm, struct msghdr *msg)
 		break;
 	case PS_COPY:	/* FALLTHROUGH */
 	case PS_UNLINK:
-		err = ps_root_dofileop(data, len, psm->ps_cmd);
+		err = ps_root_dofileop(ctx, data, len, psm->ps_cmd);
 		break;
 	default:
 		err = ps_root_os(psm, msg);
diff --git a/src/privsep.c b/src/privsep.c
index ffd32de0..af9e27bf 100644
--- a/src/privsep.c
+++ b/src/privsep.c
@@ -93,11 +93,11 @@ ps_mkdir(char *path)
 int
 ps_init(struct dhcpcd_ctx *ctx)
 {
-	struct passwd *pw;
 	char path[PATH_MAX];
+	struct passwd *pw = ctx->ps_user;
 
 	errno = 0;
-	if ((pw = getpwnam(PRIVSEP_USER)) == NULL) {
+	if ((ctx->ps_user = pw = getpwnam(PRIVSEP_USER)) == NULL) {
 		ctx->options &= ~DHCPCD_PRIVSEP;
 		if (errno == 0) {
 			logerrx("no such user %s", PRIVSEP_USER);
@@ -122,15 +122,7 @@ ps_init(struct dhcpcd_ctx *ctx)
 int
 ps_dropprivs(struct dhcpcd_ctx *ctx)
 {
-	struct passwd *pw;
-
-	if ((pw = getpwnam(PRIVSEP_USER)) == NULL) {
-		if (errno == 0)
-			logerrx("no such user %s", PRIVSEP_USER);
-		else
-			logerr("getpwnam");
-		return -1;
-	}
+	struct passwd *pw = ctx->ps_user;
 
 	if (!(ctx->options & DHCPCD_FORKED))
 		logdebugx("chrooting to `%s'", pw->pw_dir);