GopherProxy

	Make user/group-handling-code more robust - quark - quark web server
	git clone git://git.suckless.org/quark
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	---
	commit 660699492fb2275335d24fb26ec3c6529f623af0
	parent b1dca4cf97d49750134fd98f0824f7913361c9c5
	Author: Laslo Hunhold <[email protected]>
	Date: Sun, 9 Aug 2020 23:20:06 +0200

	Make user/group-handling-code more robust

	As is there is no security issue, but _if_ we end up with a user
	or group set to NULL after e.g. ARGEND, we would've hit a null-pointer-
	dereference of grp in which is now line 311.

	What we want to check instead is if user or group are NULL respectively
	and throw an error. Consequently, we can remove the later checks in the
	drop root section, as we now guarantee that grp and pwd are not NULL.

	Signed-off-by: Laslo Hunhold <[email protected]>

	Diffstat:
	M main.c \| 22 +++++++++++-----------

	1 file changed, 11 insertions(+), 11 deletions(-)
	---
	diff --git a/main.c b/main.c
	@@ -271,8 +271,8 @@ main(int argc, char *argv[])
	}

	if (udsname && (!access(udsname, F_OK) \|\| errno != ENOENT)) {
	- die("UNIX-domain socket: %s", errno ?
	- strerror(errno) : "file exists");
	+ die("UNIX-domain socket '%s': %s", udsname, errno ?
	+ strerror(errno) : "File exists");
	}

	/* compile and check the supplied vhost regexes */
	@@ -292,14 +292,14 @@ main(int argc, char *argv[])

	/* validate user and group */
	errno = 0;
	- if (user && !(pwd = getpwnam(user))) {
	- die("getpwnam '%s': %s", user, errno ? strerror(errno) :
	- "Entry not found");
	+ if (!user \|\| !(pwd = getpwnam(user))) {
	+ die("getpwnam '%s': %s", user ? user : "null",
	+ errno ? strerror(errno) : "Entry not found");
	}
	errno = 0;
	- if (group && !(grp = getgrnam(group))) {
	- die("getgrnam '%s': %s", group, errno ? strerror(errno) :
	- "Entry not found");
	+ if (!group \|\| !(grp = getgrnam(group))) {
	+ die("getgrnam '%s': %s", group ? group : "null",
	+ errno ? strerror(errno) : "Entry not found");
	}

	/* open a new process group */
	@@ -337,13 +337,13 @@ main(int argc, char *argv[])
	}

	/* drop root */
	- if (grp && setgroups(1, &(grp->gr_gid)) < 0) {
	+ if (setgroups(1, &(grp->gr_gid)) < 0) {
	die("setgroups:");
	}
	- if (grp && setgid(grp->gr_gid) < 0) {
	+ if (setgid(grp->gr_gid) < 0) {
	die("setgid:");
	}
	- if (pwd && setuid(pwd->pw_uid) < 0) {
	+ if (setuid(pwd->pw_uid) < 0) {
	die("setuid:");
	}