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authorLibravatar Linus Torvalds <torvalds@linux-foundation.org>2023-02-21 18:24:12 -0800
committerLibravatar Linus Torvalds <torvalds@linux-foundation.org>2023-02-21 18:24:12 -0800
commit5b7c4cabbb65f5c469464da6c5f614cbd7f730f2 (patch)
treecc5c2d0a898769fd59549594fedb3ee6f84e59a0 /samples/seccomp/user-trap.c
downloadlinux-5b7c4cabbb65f5c469464da6c5f614cbd7f730f2.tar.gz
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Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted
Pull networking updates from Jakub Kicinski: "Core: - Add dedicated kmem_cache for typical/small skb->head, avoid having to access struct page at kfree time, and improve memory use. - Introduce sysctl to set default RPS configuration for new netdevs. - Define Netlink protocol specification format which can be used to describe messages used by each family and auto-generate parsers. Add tools for generating kernel data structures and uAPI headers. - Expose all net/core sysctls inside netns. - Remove 4s sleep in netpoll if carrier is instantly detected on boot. - Add configurable limit of MDB entries per port, and port-vlan. - Continue populating drop reasons throughout the stack. - Retire a handful of legacy Qdiscs and classifiers. Protocols: - Support IPv4 big TCP (TSO frames larger than 64kB). - Add IP_LOCAL_PORT_RANGE socket option, to control local port range on socket by socket basis. - Track and report in procfs number of MPTCP sockets used. - Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path manager. - IPv6: don't check net.ipv6.route.max_size and rely on garbage collection to free memory (similarly to IPv4). - Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986). - ICMP: add per-rate limit counters. - Add support for user scanning requests in ieee802154. - Remove static WEP support. - Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate reporting. - WiFi 7 EHT channel puncturing support (client & AP). BPF: - Add a rbtree data structure following the "next-gen data structure" precedent set by recently added linked list, that is, by using kfunc + kptr instead of adding a new BPF map type. - Expose XDP hints via kfuncs with initial support for RX hash and timestamp metadata. - Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to better support decap on GRE tunnel devices not operating in collect metadata. - Improve x86 JIT's codegen for PROBE_MEM runtime error checks. - Remove the need for trace_printk_lock for bpf_trace_printk and bpf_trace_vprintk helpers. - Extend libbpf's bpf_tracing.h support for tracing arguments of kprobes/uprobes and syscall as a special case. - Significantly reduce the search time for module symbols by livepatch and BPF. - Enable cpumasks to be used as kptrs, which is useful for tracing programs tracking which tasks end up running on which CPUs in different time intervals. - Add support for BPF trampoline on s390x and riscv64. - Add capability to export the XDP features supported by the NIC. - Add __bpf_kfunc tag for marking kernel functions as kfuncs. - Add cgroup.memory=nobpf kernel parameter option to disable BPF memory accounting for container environments. Netfilter: - Remove the CLUSTERIP target. It has been marked as obsolete for years, and we still have WARN splats wrt races of the out-of-band /proc interface installed by this target. - Add 'destroy' commands to nf_tables. They are identical to the existing 'delete' commands, but do not return an error if the referenced object (set, chain, rule...) did not exist. Driver API: - Improve cpumask_local_spread() locality to help NICs set the right IRQ affinity on AMD platforms. - Separate C22 and C45 MDIO bus transactions more clearly. - Introduce new DCB table to control DSCP rewrite on egress. - Support configuration of Physical Layer Collision Avoidance (PLCA) Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of shared medium Ethernet. - Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing preemption of low priority frames by high priority frames. - Add support for controlling MACSec offload using netlink SET. - Rework devlink instance refcounts to allow registration and de-registration under the instance lock. Split the code into multiple files, drop some of the unnecessarily granular locks and factor out common parts of netlink operation handling. - Add TX frame aggregation parameters (for USB drivers). - Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning messages with notifications for debug. - Allow offloading of UDP NEW connections via act_ct. - Add support for per action HW stats in TC. - Support hardware miss to TC action (continue processing in SW from a specific point in the action chain). - Warn if old Wireless Extension user space interface is used with modern cfg80211/mac80211 drivers. Do not support Wireless Extensions for Wi-Fi 7 devices at all. Everyone should switch to using nl80211 interface instead. - Improve the CAN bit timing configuration. Use extack to return error messages directly to user space, update the SJW handling, including the definition of a new default value that will benefit CAN-FD controllers, by increasing their oscillator tolerance. New hardware / drivers: - Ethernet: - nVidia BlueField-3 support (control traffic driver) - Ethernet support for imx93 SoCs - Motorcomm yt8531 gigabit Ethernet PHY - onsemi NCN26000 10BASE-T1S PHY (with support for PLCA) - Microchip LAN8841 PHY (incl. cable diagnostics and PTP) - Amlogic gxl MDIO mux - WiFi: - RealTek RTL8188EU (rtl8xxxu) - Qualcomm Wi-Fi 7 devices (ath12k) - CAN: - Renesas R-Car V4H Drivers: - Bluetooth: - Set Per Platform Antenna Gain (PPAG) for Intel controllers. - Ethernet NICs: - Intel (1G, igc): - support TSN / Qbv / packet scheduling features of i226 model - Intel (100G, ice): - use GNSS subsystem instead of TTY - multi-buffer XDP support - extend support for GPIO pins to E823 devices - nVidia/Mellanox: - update the shared buffer configuration on PFC commands - implement PTP adjphase function for HW offset control - TC support for Geneve and GRE with VF tunnel offload - more efficient crypto key management method - multi-port eswitch support - Netronome/Corigine: - add DCB IEEE support - support IPsec offloading for NFP3800 - Freescale/NXP (enetc): - support XDP_REDIRECT for XDP non-linear buffers - improve reconfig, avoid link flap and waiting for idle - support MAC Merge layer - Other NICs: - sfc/ef100: add basic devlink support for ef100 - ionic: rx_push mode operation (writing descriptors via MMIO) - bnxt: use the auxiliary bus abstraction for RDMA - r8169: disable ASPM and reset bus in case of tx timeout - cpsw: support QSGMII mode for J721e CPSW9G - cpts: support pulse-per-second output - ngbe: add an mdio bus driver - usbnet: optimize usbnet_bh() by avoiding unnecessary queuing - r8152: handle devices with FW with NCM support - amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation - virtio-net: support multi buffer XDP - virtio/vsock: replace virtio_vsock_pkt with sk_buff - tsnep: XDP support - Ethernet high-speed switches: - nVidia/Mellanox (mlxsw): - add support for latency TLV (in FW control messages) - Microchip (sparx5): - separate explicit and implicit traffic forwarding rules, make the implicit rules always active - add support for egress DSCP rewrite - IS0 VCAP support (Ingress Classification) - IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS etc.) - ES2 VCAP support (Egress Access Control) - support for Per-Stream Filtering and Policing (802.1Q, 8.6.5.1) - Ethernet embedded switches: - Marvell (mv88e6xxx): - add MAB (port auth) offload support - enable PTP receive for mv88e6390 - NXP (ocelot): - support MAC Merge layer - support for the the vsc7512 internal copper phys - Microchip: - lan9303: convert to PHYLINK - lan966x: support TC flower filter statistics - lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x - lan937x: support Credit Based Shaper configuration - ksz9477: support Energy Efficient Ethernet - other: - qca8k: convert to regmap read/write API, use bulk operations - rswitch: Improve TX timestamp accuracy - Intel WiFi (iwlwifi): - EHT (Wi-Fi 7) rate reporting - STEP equalizer support: transfer some STEP (connection to radio on platforms with integrated wifi) related parameters from the BIOS to the firmware. - Qualcomm 802.11ax WiFi (ath11k): - IPQ5018 support - Fine Timing Measurement (FTM) responder role support - channel 177 support - MediaTek WiFi (mt76): - per-PHY LED support - mt7996: EHT (Wi-Fi 7) support - Wireless Ethernet Dispatch (WED) reset support - switch to using page pool allocator - RealTek WiFi (rtw89): - support new version of Bluetooth co-existance - Mobile: - rmnet: support TX aggregation" * tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits) page_pool: add a comment explaining the fragment counter usage net: ethtool: fix __ethtool_dev_mm_supported() implementation ethtool: pse-pd: Fix double word in comments xsk: add linux/vmalloc.h to xsk.c sefltests: netdevsim: wait for devlink instance after netns removal selftest: fib_tests: Always cleanup before exit net/mlx5e: Align IPsec ASO result memory to be as required by hardware net/mlx5e: TC, Set CT miss to the specific ct action instance net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG net/mlx5: Refactor tc miss handling to a single function net/mlx5: Kconfig: Make tc offload depend on tc skb extension net/sched: flower: Support hardware miss to tc action net/sched: flower: Move filter handle initialization earlier net/sched: cls_api: Support hardware miss to tc action net/sched: Rename user cookie and act cookie sfc: fix builds without CONFIG_RTC_LIB sfc: clean up some inconsistent indentings net/mlx4_en: Introduce flexible array to silence overflow warning net: lan966x: Fix possible deadlock inside PTP net/ulp: Remove redundant ->clone() test in inet_clone_ulp(). ...
Diffstat (limited to 'samples/seccomp/user-trap.c')
-rw-r--r--samples/seccomp/user-trap.c375
1 files changed, 375 insertions, 0 deletions
diff --git a/samples/seccomp/user-trap.c b/samples/seccomp/user-trap.c
new file mode 100644
index 000000000..20291ec64
--- /dev/null
+++ b/samples/seccomp/user-trap.c
@@ -0,0 +1,375 @@
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+#include <stddef.h>
+#include <sys/sysmacros.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+#include <sys/syscall.h>
+#include <sys/user.h>
+#include <sys/ioctl.h>
+#include <sys/ptrace.h>
+#include <sys/mount.h>
+#include <linux/limits.h>
+#include <linux/filter.h>
+#include <linux/seccomp.h>
+
+#define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x)))
+
+static int seccomp(unsigned int op, unsigned int flags, void *args)
+{
+ errno = 0;
+ return syscall(__NR_seccomp, op, flags, args);
+}
+
+static int send_fd(int sock, int fd)
+{
+ struct msghdr msg = {};
+ struct cmsghdr *cmsg;
+ char buf[CMSG_SPACE(sizeof(int))] = {0}, c = 'c';
+ struct iovec io = {
+ .iov_base = &c,
+ .iov_len = 1,
+ };
+
+ msg.msg_iov = &io;
+ msg.msg_iovlen = 1;
+ msg.msg_control = buf;
+ msg.msg_controllen = sizeof(buf);
+ cmsg = CMSG_FIRSTHDR(&msg);
+ cmsg->cmsg_level = SOL_SOCKET;
+ cmsg->cmsg_type = SCM_RIGHTS;
+ cmsg->cmsg_len = CMSG_LEN(sizeof(int));
+ *((int *)CMSG_DATA(cmsg)) = fd;
+ msg.msg_controllen = cmsg->cmsg_len;
+
+ if (sendmsg(sock, &msg, 0) < 0) {
+ perror("sendmsg");
+ return -1;
+ }
+
+ return 0;
+}
+
+static int recv_fd(int sock)
+{
+ struct msghdr msg = {};
+ struct cmsghdr *cmsg;
+ char buf[CMSG_SPACE(sizeof(int))] = {0}, c = 'c';
+ struct iovec io = {
+ .iov_base = &c,
+ .iov_len = 1,
+ };
+
+ msg.msg_iov = &io;
+ msg.msg_iovlen = 1;
+ msg.msg_control = buf;
+ msg.msg_controllen = sizeof(buf);
+
+ if (recvmsg(sock, &msg, 0) < 0) {
+ perror("recvmsg");
+ return -1;
+ }
+
+ cmsg = CMSG_FIRSTHDR(&msg);
+
+ return *((int *)CMSG_DATA(cmsg));
+}
+
+static int user_trap_syscall(int nr, unsigned int flags)
+{
+ struct sock_filter filter[] = {
+ BPF_STMT(BPF_LD+BPF_W+BPF_ABS,
+ offsetof(struct seccomp_data, nr)),
+ BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, nr, 0, 1),
+ BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_USER_NOTIF),
+ BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_ALLOW),
+ };
+
+ struct sock_fprog prog = {
+ .len = (unsigned short)ARRAY_SIZE(filter),
+ .filter = filter,
+ };
+
+ return seccomp(SECCOMP_SET_MODE_FILTER, flags, &prog);
+}
+
+static int handle_req(struct seccomp_notif *req,
+ struct seccomp_notif_resp *resp, int listener)
+{
+ char path[PATH_MAX], source[PATH_MAX], target[PATH_MAX];
+ int ret = -1, mem;
+
+ resp->id = req->id;
+ resp->error = -EPERM;
+ resp->val = 0;
+
+ if (req->data.nr != __NR_mount) {
+ fprintf(stderr, "huh? trapped something besides mount? %d\n", req->data.nr);
+ return -1;
+ }
+
+ /* Only allow bind mounts. */
+ if (!(req->data.args[3] & MS_BIND))
+ return 0;
+
+ /*
+ * Ok, let's read the task's memory to see where they wanted their
+ * mount to go.
+ */
+ snprintf(path, sizeof(path), "/proc/%d/mem", req->pid);
+ mem = open(path, O_RDONLY);
+ if (mem < 0) {
+ perror("open mem");
+ return -1;
+ }
+
+ /*
+ * Now we avoid a TOCTOU: we referred to a pid by its pid, but since
+ * the pid that made the syscall may have died, we need to confirm that
+ * the pid is still valid after we open its /proc/pid/mem file. We can
+ * ask the listener fd this as follows.
+ *
+ * Note that this check should occur *after* any task-specific
+ * resources are opened, to make sure that the task has not died and
+ * we're not wrongly reading someone else's state in order to make
+ * decisions.
+ */
+ if (ioctl(listener, SECCOMP_IOCTL_NOTIF_ID_VALID, &req->id) < 0) {
+ fprintf(stderr, "task died before we could map its memory\n");
+ goto out;
+ }
+
+ /*
+ * Phew, we've got the right /proc/pid/mem. Now we can read it. Note
+ * that to avoid another TOCTOU, we should read all of the pointer args
+ * before we decide to allow the syscall.
+ */
+ if (lseek(mem, req->data.args[0], SEEK_SET) < 0) {
+ perror("seek");
+ goto out;
+ }
+
+ ret = read(mem, source, sizeof(source));
+ if (ret < 0) {
+ perror("read");
+ goto out;
+ }
+
+ if (lseek(mem, req->data.args[1], SEEK_SET) < 0) {
+ perror("seek");
+ goto out;
+ }
+
+ ret = read(mem, target, sizeof(target));
+ if (ret < 0) {
+ perror("read");
+ goto out;
+ }
+
+ /*
+ * Our policy is to only allow bind mounts inside /tmp. This isn't very
+ * interesting, because we could do unprivlieged bind mounts with user
+ * namespaces already, but you get the idea.
+ */
+ if (!strncmp(source, "/tmp/", 5) && !strncmp(target, "/tmp/", 5)) {
+ if (mount(source, target, NULL, req->data.args[3], NULL) < 0) {
+ ret = -1;
+ perror("actual mount");
+ goto out;
+ }
+ resp->error = 0;
+ }
+
+ /* Even if we didn't allow it because of policy, generating the
+ * response was be a success, because we want to tell the worker EPERM.
+ */
+ ret = 0;
+
+out:
+ close(mem);
+ return ret;
+}
+
+int main(void)
+{
+ int sk_pair[2], ret = 1, status, listener;
+ pid_t worker = 0 , tracer = 0;
+
+ if (socketpair(PF_LOCAL, SOCK_SEQPACKET, 0, sk_pair) < 0) {
+ perror("socketpair");
+ return 1;
+ }
+
+ worker = fork();
+ if (worker < 0) {
+ perror("fork");
+ goto close_pair;
+ }
+
+ if (worker == 0) {
+ listener = user_trap_syscall(__NR_mount,
+ SECCOMP_FILTER_FLAG_NEW_LISTENER);
+ if (listener < 0) {
+ perror("seccomp");
+ exit(1);
+ }
+
+ /*
+ * Drop privileges. We definitely can't mount as uid 1000.
+ */
+ if (setuid(1000) < 0) {
+ perror("setuid");
+ exit(1);
+ }
+
+ /*
+ * Send the listener to the parent; also serves as
+ * synchronization.
+ */
+ if (send_fd(sk_pair[1], listener) < 0)
+ exit(1);
+ close(listener);
+
+ if (mkdir("/tmp/foo", 0755) < 0) {
+ perror("mkdir");
+ exit(1);
+ }
+
+ /*
+ * Try a bad mount just for grins.
+ */
+ if (mount("/dev/sda", "/tmp/foo", NULL, 0, NULL) != -1) {
+ fprintf(stderr, "huh? mounted /dev/sda?\n");
+ exit(1);
+ }
+
+ if (errno != EPERM) {
+ perror("bad error from mount");
+ exit(1);
+ }
+
+ /*
+ * Ok, we expect this one to succeed.
+ */
+ if (mount("/tmp/foo", "/tmp/foo", NULL, MS_BIND, NULL) < 0) {
+ perror("mount");
+ exit(1);
+ }
+
+ exit(0);
+ }
+
+ /*
+ * Get the listener from the child.
+ */
+ listener = recv_fd(sk_pair[0]);
+ if (listener < 0)
+ goto out_kill;
+
+ /*
+ * Fork a task to handle the requests. This isn't strictly necessary,
+ * but it makes the particular writing of this sample easier, since we
+ * can just wait ofr the tracee to exit and kill the tracer.
+ */
+ tracer = fork();
+ if (tracer < 0) {
+ perror("fork");
+ goto out_kill;
+ }
+
+ if (tracer == 0) {
+ struct seccomp_notif *req;
+ struct seccomp_notif_resp *resp;
+ struct seccomp_notif_sizes sizes;
+
+ if (seccomp(SECCOMP_GET_NOTIF_SIZES, 0, &sizes) < 0) {
+ perror("seccomp(GET_NOTIF_SIZES)");
+ goto out_close;
+ }
+
+ req = malloc(sizes.seccomp_notif);
+ if (!req)
+ goto out_close;
+
+ resp = malloc(sizes.seccomp_notif_resp);
+ if (!resp)
+ goto out_req;
+ memset(resp, 0, sizes.seccomp_notif_resp);
+
+ while (1) {
+ memset(req, 0, sizes.seccomp_notif);
+ if (ioctl(listener, SECCOMP_IOCTL_NOTIF_RECV, req)) {
+ perror("ioctl recv");
+ goto out_resp;
+ }
+
+ if (handle_req(req, resp, listener) < 0)
+ goto out_resp;
+
+ /*
+ * ENOENT here means that the task may have gotten a
+ * signal and restarted the syscall. It's up to the
+ * handler to decide what to do in this case, but for
+ * the sample code, we just ignore it. Probably
+ * something better should happen, like undoing the
+ * mount, or keeping track of the args to make sure we
+ * don't do it again.
+ */
+ if (ioctl(listener, SECCOMP_IOCTL_NOTIF_SEND, resp) < 0 &&
+ errno != ENOENT) {
+ perror("ioctl send");
+ goto out_resp;
+ }
+ }
+out_resp:
+ free(resp);
+out_req:
+ free(req);
+out_close:
+ close(listener);
+ exit(1);
+ }
+
+ close(listener);
+
+ if (waitpid(worker, &status, 0) != worker) {
+ perror("waitpid");
+ goto out_kill;
+ }
+
+ if (umount2("/tmp/foo", MNT_DETACH) < 0 && errno != EINVAL) {
+ perror("umount2");
+ goto out_kill;
+ }
+
+ if (remove("/tmp/foo") < 0 && errno != ENOENT) {
+ perror("remove");
+ exit(1);
+ }
+
+ if (!WIFEXITED(status) || WEXITSTATUS(status)) {
+ fprintf(stderr, "worker exited nonzero\n");
+ goto out_kill;
+ }
+
+ ret = 0;
+
+out_kill:
+ if (tracer > 0)
+ kill(tracer, SIGKILL);
+ if (worker > 0)
+ kill(worker, SIGKILL);
+
+close_pair:
+ close(sk_pair[0]);
+ close(sk_pair[1]);
+ return ret;
+}