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daemon: Make 'profiles/per-user' non-world-writable.

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Fixes <https://bugs.gnu.org/37744>.
Reported at <https://www.openwall.com/lists/oss-security/2019/10/09/4>.

Based on Nix commit 5a303093dcae1e5ce9212616ef18f2ca51020b0d
by Eelco Dolstra <edolstra@gmail.com>.

* nix/libstore/local-store.cc (LocalStore::LocalStore): Set 'perUserDir'
to #o755 instead of #o1777.
(LocalStore::createUser): New function.
* nix/libstore/local-store.hh (LocalStore): Add it.
* nix/libstore/store-api.hh (StoreAPI): Add it.
* nix/nix-daemon/nix-daemon.cc (performOp): In 'wopSetOptions', add
condition to handle "user-name" property and honor it.
(processConnection): Add 'userId' parameter.  Call 'store->createUser'
when userId is not -1.
* guix/profiles.scm (ensure-profile-directory): Note that this is now
handled by the daemon.
* guix/store.scm (current-user-name): New procedure.
(set-build-options): Add #:user-name parameter and pass it to the daemon.
* tests/guix-daemon.sh: Test the creation of 'profiles/per-user' when
listening on a TCP socket.
* tests/store.scm ("profiles/per-user exists and is not writable")
("profiles/per-user/$USER exists"): New tests.
This commit is contained in:
Ludovic Courtès 2019-10-16 11:51:42 +02:00
parent a1aaca314c
commit 81c580c866
No known key found for this signature in database
GPG key ID: 090B11993D9AEBB5
8 changed files with 90 additions and 6 deletions
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3
guix/profiles.scm
View file

@ -1732,7 +1732,8 @@ because the NUMBER is zero.)"
(string-append %profile-directory "/guix-profile"))
(define (ensure-profile-directory)
"Attempt to create /…/profiles/per-user/$USER if needed."
"Attempt to create /…/profiles/per-user/$USER if needed. Nowadays this is
taken care of by the daemon."
(let ((s (stat %profile-directory #f)))
(unless (and s (eq? 'directory (stat:type s)))
(catch 'system-error

12
guix/store.scm
View file

@ -748,6 +748,14 @@ encoding conversion errors."
(cut string-append "http://" <>))
'("ci.guix.gnu.org")))
(define (current-user-name)
"Return the name of the calling user."
(catch #t
(lambda ()
(passwd:name (getpwuid (getuid))))
(lambda _
(getenv "USER"))))
(define* (set-build-options server
#:key keep-failed? keep-going? fallback?
(verbosity 0)
@ -759,6 +767,7 @@ encoding conversion errors."
(build-verbosity 0)
(log-type 0)
(print-build-trace #t)
(user-name (current-user-name))
;; When true, provide machine-readable "build
;; traces" for use by (guix status). Old clients
@ -849,6 +858,9 @@ encoding conversion errors."
`(("build-repeat"
. ,(number->string (max 0 (1- rounds)))))
'())
,@(if user-name
`(("user-name" . ,user-name))
'())
,@(if terminal-columns
`(("terminal-columns"
. ,(number->string terminal-columns)))

17
nix/libstore/local-store.cc
View file

@ -88,8 +88,9 @@ LocalStore::LocalStore(bool reserveSpace)
Path perUserDir = profilesDir + "/per-user";
createDirs(perUserDir);
if (chmod(perUserDir.c_str(), 01777) == -1)
throw SysError(format("could not set permissions on '%1%' to 1777") % perUserDir);
if (chmod(perUserDir.c_str(), 0755) == -1)
throw SysError(format("could not set permissions on '%1%' to 755")
% perUserDir);
mode_t perm = 01775;
@ -1642,4 +1643,16 @@ void LocalStore::vacuumDB()
}
void LocalStore::createUser(const std::string & userName, uid_t userId)
{
auto dir = settings.nixStateDir + "/profiles/per-user/" + userName;
createDirs(dir);
if (chmod(dir.c_str(), 0755) == -1)
throw SysError(format("changing permissions of directory '%s'") % dir);
if (chown(dir.c_str(), userId, -1) == -1)
throw SysError(format("changing owner of directory '%s'") % dir);
}
}

2
nix/libstore/local-store.hh
View file

@ -180,6 +180,8 @@ public:
void setSubstituterEnv();
void createUser(const std::string & userName, uid_t userId);
private:
Path schemaPath;

4
nix/libstore/store-api.hh
View file

@ -289,6 +289,10 @@ public:
/* Check the integrity of the Nix store. Returns true if errors
remain. */
virtual bool verifyStore(bool checkContents, bool repair) = 0;
/* Create a profile for the given user. This is done by the daemon
because the 'profiles/per-user' directory is not writable by users. */
virtual void createUser(const std::string & userName, uid_t userId) = 0;
};

24
nix/nix-daemon/nix-daemon.cc
View file

@ -613,6 +613,17 @@ static void performOp(bool trusted, unsigned int clientVersion,
|| name == "build-repeat"
|| name == "multiplexed-build-output")
settings.set(name, value);
else if (name == "user-name"
&& settings.clientUid == (uid_t) -1) {
/* Create the user profile. This is necessary if
clientUid = -1, for instance because the client
connected over TCP. */
struct passwd *pw = getpwnam(value.c_str());
if (pw != NULL)
store->createUser(value, pw->pw_uid);
else
printMsg(lvlInfo, format("user name %1% not found") % value);
}
else
settings.set(trusted ? name : "untrusted-" + name, value);
}
@ -731,7 +742,7 @@ static void performOp(bool trusted, unsigned int clientVersion,
}
static void processConnection(bool trusted)
static void processConnection(bool trusted, uid_t userId)
{
canSendStderr = false;
_writeToStderr = tunnelStderr;
@ -778,6 +789,15 @@ static void processConnection(bool trusted)
/* Open the store. */
store = std::shared_ptr<StoreAPI>(new LocalStore(reserveSpace));
if (userId != (uid_t) -1) {
/* Create the user profile. */
struct passwd *pw = getpwuid(userId);
if (pw != NULL && pw->pw_name != NULL)
store->createUser(pw->pw_name, userId);
else
printMsg(lvlInfo, format("user with UID %1% not found") % userId);
}
stopWork();
to.flush();
@ -963,7 +983,7 @@ static void acceptConnection(int fdSocket)
/* Handle the connection. */
from.fd = remote;
to.fd = remote;
processConnection(trusted);
processConnection(trusted, clientUid);
exit(0);
}, false, "unexpected build daemon error: ", true);

21
tests/guix-daemon.sh
View file

@ -94,6 +94,27 @@ done
kill "$daemon_pid"
# Make sure 'profiles/per-user' is created when connecting over TCP.
orig_GUIX_STATE_DIRECTORY="$GUIX_STATE_DIRECTORY"
GUIX_STATE_DIRECTORY="$GUIX_STATE_DIRECTORY-2"
guix-daemon --disable-chroot --listen="localhost:9877" &
daemon_pid=$!
GUIX_DAEMON_SOCKET="guix://localhost:9877"
export GUIX_DAEMON_SOCKET
test ! -d "$GUIX_STATE_DIRECTORY/profiles/per-user"
guix build guile-bootstrap -d
test -d "$GUIX_STATE_DIRECTORY/profiles/per-user/$USER"
kill "$daemon_pid"
unset GUIX_DAEMON_SOCKET
GUIX_STATE_DIRECTORY="$orig_GUIX_STATE_DIRECTORY"
# Check the failed build cache.
guix-daemon --no-substitutes --listen="$socket" --disable-chroot \

13
tests/store.scm
View file

@ -18,6 +18,7 @@
(define-module (test-store)
#:use-module (guix tests)
#:use-module (guix config)
#:use-module (guix store)
#:use-module (guix utils)
#:use-module (guix monads)
@ -102,7 +103,17 @@
"/283gqy39v3g9dxjy26rynl0zls82fmcg-guile-2.0.7/bin/guile")))
(not (direct-store-path? (%store-prefix)))))
(test-skip (if %store 0 13))
(test-skip (if %store 0 15))
(test-equal "profiles/per-user exists and is not writable"
#o755
(stat:perms (stat (string-append %state-directory "/profiles/per-user"))))
(test-equal "profiles/per-user/$USER exists"
(list (getuid) #o755)
(let ((s (stat (string-append %state-directory "/profiles/per-user/"
(passwd:name (getpwuid (getuid)))))))
(list (stat:uid s) (stat:perms s))))
(test-equal "add-data-to-store"
#vu8(1 2 3 4 5)