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().
  ...

1 files changed, 926 insertions, 0 deletions

diff --git a/kernel/cred.c b/kernel/cred.c
new file mode 100644
index 000000000..811ad654a
--- /dev/null
+++ b/kernel/cred.c
@@ -0,0 +1,926 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Task credentials management - see Documentation/security/credentials.rst
+ *
+ * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+#include <linux/export.h>
+#include <linux/cred.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/sched/coredump.h>
+#include <linux/key.h>
+#include <linux/keyctl.h>
+#include <linux/init_task.h>
+#include <linux/security.h>
+#include <linux/binfmts.h>
+#include <linux/cn_proc.h>
+#include <linux/uidgid.h>
+
+#if 0
+#define kdebug(FMT, ...)						\
+	printk("[%-5.5s%5u] " FMT "\n",					\
+	       current->comm, current->pid, ##__VA_ARGS__)
+#else
+#define kdebug(FMT, ...)						\
+do {									\
+	if (0)								\
+		no_printk("[%-5.5s%5u] " FMT "\n",			\
+			  current->comm, current->pid, ##__VA_ARGS__);	\
+} while (0)
+#endif
+
+static struct kmem_cache *cred_jar;
+
+/* init to 2 - one for init_task, one to ensure it is never freed */
+static struct group_info init_groups = { .usage = ATOMIC_INIT(2) };
+
+/*
+ * The initial credentials for the initial task
+ */
+struct cred init_cred = {
+	.usage			= ATOMIC_INIT(4),
+#ifdef CONFIG_DEBUG_CREDENTIALS
+	.subscribers		= ATOMIC_INIT(2),
+	.magic			= CRED_MAGIC,
+#endif
+	.uid			= GLOBAL_ROOT_UID,
+	.gid			= GLOBAL_ROOT_GID,
+	.suid			= GLOBAL_ROOT_UID,
+	.sgid			= GLOBAL_ROOT_GID,
+	.euid			= GLOBAL_ROOT_UID,
+	.egid			= GLOBAL_ROOT_GID,
+	.fsuid			= GLOBAL_ROOT_UID,
+	.fsgid			= GLOBAL_ROOT_GID,
+	.securebits		= SECUREBITS_DEFAULT,
+	.cap_inheritable	= CAP_EMPTY_SET,
+	.cap_permitted		= CAP_FULL_SET,
+	.cap_effective		= CAP_FULL_SET,
+	.cap_bset		= CAP_FULL_SET,
+	.user			= INIT_USER,
+	.user_ns		= &init_user_ns,
+	.group_info		= &init_groups,
+	.ucounts		= &init_ucounts,
+};
+
+static inline void set_cred_subscribers(struct cred *cred, int n)
+{
+#ifdef CONFIG_DEBUG_CREDENTIALS
+	atomic_set(&cred->subscribers, n);
+#endif
+}
+
+static inline int read_cred_subscribers(const struct cred *cred)
+{
+#ifdef CONFIG_DEBUG_CREDENTIALS
+	return atomic_read(&cred->subscribers);
+#else
+	return 0;
+#endif
+}
+
+static inline void alter_cred_subscribers(const struct cred *_cred, int n)
+{
+#ifdef CONFIG_DEBUG_CREDENTIALS
+	struct cred *cred = (struct cred *) _cred;
+
+	atomic_add(n, &cred->subscribers);
+#endif
+}
+
+/*
+ * The RCU callback to actually dispose of a set of credentials
+ */
+static void put_cred_rcu(struct rcu_head *rcu)
+{
+	struct cred *cred = container_of(rcu, struct cred, rcu);
+
+	kdebug("put_cred_rcu(%p)", cred);
+
+#ifdef CONFIG_DEBUG_CREDENTIALS
+	if (cred->magic != CRED_MAGIC_DEAD ||
+	    atomic_read(&cred->usage) != 0 ||
+	    read_cred_subscribers(cred) != 0)
+		panic("CRED: put_cred_rcu() sees %p with"
+		      " mag %x, put %p, usage %d, subscr %d\n",
+		      cred, cred->magic, cred->put_addr,
+		      atomic_read(&cred->usage),
+		      read_cred_subscribers(cred));
+#else
+	if (atomic_read(&cred->usage) != 0)
+		panic("CRED: put_cred_rcu() sees %p with usage %d\n",
+		      cred, atomic_read(&cred->usage));
+#endif
+
+	security_cred_free(cred);
+	key_put(cred->session_keyring);
+	key_put(cred->process_keyring);
+	key_put(cred->thread_keyring);
+	key_put(cred->request_key_auth);
+	if (cred->group_info)
+		put_group_info(cred->group_info);
+	free_uid(cred->user);
+	if (cred->ucounts)
+		put_ucounts(cred->ucounts);
+	put_user_ns(cred->user_ns);
+	kmem_cache_free(cred_jar, cred);
+}
+
+/**
+ * __put_cred - Destroy a set of credentials
+ * @cred: The record to release
+ *
+ * Destroy a set of credentials on which no references remain.
+ */
+void __put_cred(struct cred *cred)
+{
+	kdebug("__put_cred(%p{%d,%d})", cred,
+	       atomic_read(&cred->usage),
+	       read_cred_subscribers(cred));
+
+	BUG_ON(atomic_read(&cred->usage) != 0);
+#ifdef CONFIG_DEBUG_CREDENTIALS
+	BUG_ON(read_cred_subscribers(cred) != 0);
+	cred->magic = CRED_MAGIC_DEAD;
+	cred->put_addr = __builtin_return_address(0);
+#endif
+	BUG_ON(cred == current->cred);
+	BUG_ON(cred == current->real_cred);
+
+	if (cred->non_rcu)
+		put_cred_rcu(&cred->rcu);
+	else
+		call_rcu(&cred->rcu, put_cred_rcu);
+}
+EXPORT_SYMBOL(__put_cred);
+
+/*
+ * Clean up a task's credentials when it exits
+ */
+void exit_creds(struct task_struct *tsk)
+{
+	struct cred *cred;
+
+	kdebug("exit_creds(%u,%p,%p,{%d,%d})", tsk->pid, tsk->real_cred, tsk->cred,
+	       atomic_read(&tsk->cred->usage),
+	       read_cred_subscribers(tsk->cred));
+
+	cred = (struct cred *) tsk->real_cred;
+	tsk->real_cred = NULL;
+	validate_creds(cred);
+	alter_cred_subscribers(cred, -1);
+	put_cred(cred);
+
+	cred = (struct cred *) tsk->cred;
+	tsk->cred = NULL;
+	validate_creds(cred);
+	alter_cred_subscribers(cred, -1);
+	put_cred(cred);
+
+#ifdef CONFIG_KEYS_REQUEST_CACHE
+	key_put(tsk->cached_requested_key);
+	tsk->cached_requested_key = NULL;
+#endif
+}
+
+/**
+ * get_task_cred - Get another task's objective credentials
+ * @task: The task to query
+ *
+ * Get the objective credentials of a task, pinning them so that they can't go
+ * away.  Accessing a task's credentials directly is not permitted.
+ *
+ * The caller must also make sure task doesn't get deleted, either by holding a
+ * ref on task or by holding tasklist_lock to prevent it from being unlinked.
+ */
+const struct cred *get_task_cred(struct task_struct *task)
+{
+	const struct cred *cred;
+
+	rcu_read_lock();
+
+	do {
+		cred = __task_cred((task));
+		BUG_ON(!cred);
+	} while (!get_cred_rcu(cred));
+
+	rcu_read_unlock();
+	return cred;
+}
+EXPORT_SYMBOL(get_task_cred);
+
+/*
+ * Allocate blank credentials, such that the credentials can be filled in at a
+ * later date without risk of ENOMEM.
+ */
+struct cred *cred_alloc_blank(void)
+{
+	struct cred *new;
+
+	new = kmem_cache_zalloc(cred_jar, GFP_KERNEL);
+	if (!new)
+		return NULL;
+
+	atomic_set(&new->usage, 1);
+#ifdef CONFIG_DEBUG_CREDENTIALS
+	new->magic = CRED_MAGIC;
+#endif
+	if (security_cred_alloc_blank(new, GFP_KERNEL_ACCOUNT) < 0)
+		goto error;
+
+	return new;
+
+error:
+	abort_creds(new);
+	return NULL;
+}
+
+/**
+ * prepare_creds - Prepare a new set of credentials for modification
+ *
+ * Prepare a new set of task credentials for modification.  A task's creds
+ * shouldn't generally be modified directly, therefore this function is used to
+ * prepare a new copy, which the caller then modifies and then commits by
+ * calling commit_creds().
+ *
+ * Preparation involves making a copy of the objective creds for modification.
+ *
+ * Returns a pointer to the new creds-to-be if successful, NULL otherwise.
+ *
+ * Call commit_creds() or abort_creds() to clean up.
+ */
+struct cred *prepare_creds(void)
+{
+	struct task_struct *task = current;
+	const struct cred *old;
+	struct cred *new;
+
+	validate_process_creds();
+
+	new = kmem_cache_alloc(cred_jar, GFP_KERNEL);
+	if (!new)
+		return NULL;
+
+	kdebug("prepare_creds() alloc %p", new);
+
+	old = task->cred;
+	memcpy(new, old, sizeof(struct cred));
+
+	new->non_rcu = 0;
+	atomic_set(&new->usage, 1);
+	set_cred_subscribers(new, 0);
+	get_group_info(new->group_info);
+	get_uid(new->user);
+	get_user_ns(new->user_ns);
+
+#ifdef CONFIG_KEYS
+	key_get(new->session_keyring);
+	key_get(new->process_keyring);
+	key_get(new->thread_keyring);
+	key_get(new->request_key_auth);
+#endif
+
+#ifdef CONFIG_SECURITY
+	new->security = NULL;
+#endif
+
+	new->ucounts = get_ucounts(new->ucounts);
+	if (!new->ucounts)
+		goto error;
+
+	if (security_prepare_creds(new, old, GFP_KERNEL_ACCOUNT) < 0)
+		goto error;
+
+	validate_creds(new);
+	return new;
+
+error:
+	abort_creds(new);
+	return NULL;
+}
+EXPORT_SYMBOL(prepare_creds);
+
+/*
+ * Prepare credentials for current to perform an execve()
+ * - The caller must hold ->cred_guard_mutex
+ */
+struct cred *prepare_exec_creds(void)
+{
+	struct cred *new;
+
+	new = prepare_creds();
+	if (!new)
+		return new;
+
+#ifdef CONFIG_KEYS
+	/* newly exec'd tasks don't get a thread keyring */
+	key_put(new->thread_keyring);
+	new->thread_keyring = NULL;
+
+	/* inherit the session keyring; new process keyring */
+	key_put(new->process_keyring);
+	new->process_keyring = NULL;
+#endif
+
+	new->suid = new->fsuid = new->euid;
+	new->sgid = new->fsgid = new->egid;
+
+	return new;
+}
+
+/*
+ * Copy credentials for the new process created by fork()
+ *
+ * We share if we can, but under some circumstances we have to generate a new
+ * set.
+ *
+ * The new process gets the current process's subjective credentials as its
+ * objective and subjective credentials
+ */
+int copy_creds(struct task_struct *p, unsigned long clone_flags)
+{
+	struct cred *new;
+	int ret;
+
+#ifdef CONFIG_KEYS_REQUEST_CACHE
+	p->cached_requested_key = NULL;
+#endif
+
+	if (
+#ifdef CONFIG_KEYS
+		!p->cred->thread_keyring &&
+#endif
+		clone_flags & CLONE_THREAD
+	    ) {
+		p->real_cred = get_cred(p->cred);
+		get_cred(p->cred);
+		alter_cred_subscribers(p->cred, 2);
+		kdebug("share_creds(%p{%d,%d})",
+		       p->cred, atomic_read(&p->cred->usage),
+		       read_cred_subscribers(p->cred));
+		inc_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
+		return 0;
+	}
+
+	new = prepare_creds();
+	if (!new)
+		return -ENOMEM;
+
+	if (clone_flags & CLONE_NEWUSER) {
+		ret = create_user_ns(new);
+		if (ret < 0)
+			goto error_put;
+		ret = set_cred_ucounts(new);
+		if (ret < 0)
+			goto error_put;
+	}
+
+#ifdef CONFIG_KEYS
+	/* new threads get their own thread keyrings if their parent already
+	 * had one */
+	if (new->thread_keyring) {
+		key_put(new->thread_keyring);
+		new->thread_keyring = NULL;
+		if (clone_flags & CLONE_THREAD)
+			install_thread_keyring_to_cred(new);
+	}
+
+	/* The process keyring is only shared between the threads in a process;
+	 * anything outside of those threads doesn't inherit.
+	 */
+	if (!(clone_flags & CLONE_THREAD)) {
+		key_put(new->process_keyring);
+		new->process_keyring = NULL;
+	}
+#endif
+
+	p->cred = p->real_cred = get_cred(new);
+	inc_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
+	alter_cred_subscribers(new, 2);
+	validate_creds(new);
+	return 0;
+
+error_put:
+	put_cred(new);
+	return ret;
+}
+
+static bool cred_cap_issubset(const struct cred *set, const struct cred *subset)
+{
+	const struct user_namespace *set_ns = set->user_ns;
+	const struct user_namespace *subset_ns = subset->user_ns;
+
+	/* If the two credentials are in the same user namespace see if
+	 * the capabilities of subset are a subset of set.
+	 */
+	if (set_ns == subset_ns)
+		return cap_issubset(subset->cap_permitted, set->cap_permitted);
+
+	/* The credentials are in a different user namespaces
+	 * therefore one is a subset of the other only if a set is an
+	 * ancestor of subset and set->euid is owner of subset or one
+	 * of subsets ancestors.
+	 */
+	for (;subset_ns != &init_user_ns; subset_ns = subset_ns->parent) {
+		if ((set_ns == subset_ns->parent)  &&
+		    uid_eq(subset_ns->owner, set->euid))
+			return true;
+	}
+
+	return false;
+}
+
+/**
+ * commit_creds - Install new credentials upon the current task
+ * @new: The credentials to be assigned
+ *
+ * Install a new set of credentials to the current task, using RCU to replace
+ * the old set.  Both the objective and the subjective credentials pointers are
+ * updated.  This function may not be called if the subjective credentials are
+ * in an overridden state.
+ *
+ * This function eats the caller's reference to the new credentials.
+ *
+ * Always returns 0 thus allowing this function to be tail-called at the end
+ * of, say, sys_setgid().
+ */
+int commit_creds(struct cred *new)
+{
+	struct task_struct *task = current;
+	const struct cred *old = task->real_cred;
+
+	kdebug("commit_creds(%p{%d,%d})", new,
+	       atomic_read(&new->usage),
+	       read_cred_subscribers(new));
+
+	BUG_ON(task->cred != old);
+#ifdef CONFIG_DEBUG_CREDENTIALS
+	BUG_ON(read_cred_subscribers(old) < 2);
+	validate_creds(old);
+	validate_creds(new);
+#endif
+	BUG_ON(atomic_read(&new->usage) < 1);
+
+	get_cred(new); /* we will require a ref for the subj creds too */
+
+	/* dumpability changes */
+	if (!uid_eq(old->euid, new->euid) ||
+	    !gid_eq(old->egid, new->egid) ||
+	    !uid_eq(old->fsuid, new->fsuid) ||
+	    !gid_eq(old->fsgid, new->fsgid) ||
+	    !cred_cap_issubset(old, new)) {
+		if (task->mm)
+			set_dumpable(task->mm, suid_dumpable);
+		task->pdeath_signal = 0;
+		/*
+		 * If a task drops privileges and becomes nondumpable,
+		 * the dumpability change must become visible before
+		 * the credential change; otherwise, a __ptrace_may_access()
+		 * racing with this change may be able to attach to a task it
+		 * shouldn't be able to attach to (as if the task had dropped
+		 * privileges without becoming nondumpable).
+		 * Pairs with a read barrier in __ptrace_may_access().
+		 */
+		smp_wmb();
+	}
+
+	/* alter the thread keyring */
+	if (!uid_eq(new->fsuid, old->fsuid))
+		key_fsuid_changed(new);
+	if (!gid_eq(new->fsgid, old->fsgid))
+		key_fsgid_changed(new);
+
+	/* do it
+	 * RLIMIT_NPROC limits on user->processes have already been checked
+	 * in set_user().
+	 */
+	alter_cred_subscribers(new, 2);
+	if (new->user != old->user || new->user_ns != old->user_ns)
+		inc_rlimit_ucounts(new->ucounts, UCOUNT_RLIMIT_NPROC, 1);
+	rcu_assign_pointer(task->real_cred, new);
+	rcu_assign_pointer(task->cred, new);
+	if (new->user != old->user || new->user_ns != old->user_ns)
+		dec_rlimit_ucounts(old->ucounts, UCOUNT_RLIMIT_NPROC, 1);
+	alter_cred_subscribers(old, -2);
+
+	/* send notifications */
+	if (!uid_eq(new->uid,   old->uid)  ||
+	    !uid_eq(new->euid,  old->euid) ||
+	    !uid_eq(new->suid,  old->suid) ||
+	    !uid_eq(new->fsuid, old->fsuid))
+		proc_id_connector(task, PROC_EVENT_UID);
+
+	if (!gid_eq(new->gid,   old->gid)  ||
+	    !gid_eq(new->egid,  old->egid) ||
+	    !gid_eq(new->sgid,  old->sgid) ||
+	    !gid_eq(new->fsgid, old->fsgid))
+		proc_id_connector(task, PROC_EVENT_GID);
+
+	/* release the old obj and subj refs both */
+	put_cred(old);
+	put_cred(old);
+	return 0;
+}
+EXPORT_SYMBOL(commit_creds);
+
+/**
+ * abort_creds - Discard a set of credentials and unlock the current task
+ * @new: The credentials that were going to be applied
+ *
+ * Discard a set of credentials that were under construction and unlock the
+ * current task.
+ */
+void abort_creds(struct cred *new)
+{
+	kdebug("abort_creds(%p{%d,%d})", new,
+	       atomic_read(&new->usage),
+	       read_cred_subscribers(new));
+
+#ifdef CONFIG_DEBUG_CREDENTIALS
+	BUG_ON(read_cred_subscribers(new) != 0);
+#endif
+	BUG_ON(atomic_read(&new->usage) < 1);
+	put_cred(new);
+}
+EXPORT_SYMBOL(abort_creds);
+
+/**
+ * override_creds - Override the current process's subjective credentials
+ * @new: The credentials to be assigned
+ *
+ * Install a set of temporary override subjective credentials on the current
+ * process, returning the old set for later reversion.
+ */
+const struct cred *override_creds(const struct cred *new)
+{
+	const struct cred *old = current->cred;
+
+	kdebug("override_creds(%p{%d,%d})", new,
+	       atomic_read(&new->usage),
+	       read_cred_subscribers(new));
+
+	validate_creds(old);
+	validate_creds(new);
+
+	/*
+	 * NOTE! This uses 'get_new_cred()' rather than 'get_cred()'.
+	 *
+	 * That means that we do not clear the 'non_rcu' flag, since
+	 * we are only installing the cred into the thread-synchronous
+	 * '->cred' pointer, not the '->real_cred' pointer that is
+	 * visible to other threads under RCU.
+	 *
+	 * Also note that we did validate_creds() manually, not depending
+	 * on the validation in 'get_cred()'.
+	 */
+	get_new_cred((struct cred *)new);
+	alter_cred_subscribers(new, 1);
+	rcu_assign_pointer(current->cred, new);
+	alter_cred_subscribers(old, -1);
+
+	kdebug("override_creds() = %p{%d,%d}", old,
+	       atomic_read(&old->usage),
+	       read_cred_subscribers(old));
+	return old;
+}
+EXPORT_SYMBOL(override_creds);
+
+/**
+ * revert_creds - Revert a temporary subjective credentials override
+ * @old: The credentials to be restored
+ *
+ * Revert a temporary set of override subjective credentials to an old set,
+ * discarding the override set.
+ */
+void revert_creds(const struct cred *old)
+{
+	const struct cred *override = current->cred;
+
+	kdebug("revert_creds(%p{%d,%d})", old,
+	       atomic_read(&old->usage),
+	       read_cred_subscribers(old));
+
+	validate_creds(old);
+	validate_creds(override);
+	alter_cred_subscribers(old, 1);
+	rcu_assign_pointer(current->cred, old);
+	alter_cred_subscribers(override, -1);
+	put_cred(override);
+}
+EXPORT_SYMBOL(revert_creds);
+
+/**
+ * cred_fscmp - Compare two credentials with respect to filesystem access.
+ * @a: The first credential
+ * @b: The second credential
+ *
+ * cred_cmp() will return zero if both credentials have the same
+ * fsuid, fsgid, and supplementary groups.  That is, if they will both
+ * provide the same access to files based on mode/uid/gid.
+ * If the credentials are different, then either -1 or 1 will
+ * be returned depending on whether @a comes before or after @b
+ * respectively in an arbitrary, but stable, ordering of credentials.
+ *
+ * Return: -1, 0, or 1 depending on comparison
+ */
+int cred_fscmp(const struct cred *a, const struct cred *b)
+{
+	struct group_info *ga, *gb;
+	int g;
+
+	if (a == b)
+		return 0;
+	if (uid_lt(a->fsuid, b->fsuid))
+		return -1;
+	if (uid_gt(a->fsuid, b->fsuid))
+		return 1;
+
+	if (gid_lt(a->fsgid, b->fsgid))
+		return -1;
+	if (gid_gt(a->fsgid, b->fsgid))
+		return 1;
+
+	ga = a->group_info;
+	gb = b->group_info;
+	if (ga == gb)
+		return 0;
+	if (ga == NULL)
+		return -1;
+	if (gb == NULL)
+		return 1;
+	if (ga->ngroups < gb->ngroups)
+		return -1;
+	if (ga->ngroups > gb->ngroups)
+		return 1;
+
+	for (g = 0; g < ga->ngroups; g++) {
+		if (gid_lt(ga->gid[g], gb->gid[g]))
+			return -1;
+		if (gid_gt(ga->gid[g], gb->gid[g]))
+			return 1;
+	}
+	return 0;
+}
+EXPORT_SYMBOL(cred_fscmp);
+
+int set_cred_ucounts(struct cred *new)
+{
+	struct ucounts *new_ucounts, *old_ucounts = new->ucounts;
+
+	/*
+	 * This optimization is needed because alloc_ucounts() uses locks
+	 * for table lookups.
+	 */
+	if (old_ucounts->ns == new->user_ns && uid_eq(old_ucounts->uid, new->uid))
+		return 0;
+
+	if (!(new_ucounts = alloc_ucounts(new->user_ns, new->uid)))
+		return -EAGAIN;
+
+	new->ucounts = new_ucounts;
+	put_ucounts(old_ucounts);
+
+	return 0;
+}
+
+/*
+ * initialise the credentials stuff
+ */
+void __init cred_init(void)
+{
+	/* allocate a slab in which we can store credentials */
+	cred_jar = kmem_cache_create("cred_jar", sizeof(struct cred), 0,
+			SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, NULL);
+}
+
+/**
+ * prepare_kernel_cred - Prepare a set of credentials for a kernel service
+ * @daemon: A userspace daemon to be used as a reference
+ *
+ * Prepare a set of credentials for a kernel service.  This can then be used to
+ * override a task's own credentials so that work can be done on behalf of that
+ * task that requires a different subjective context.
+ *
+ * @daemon is used to provide a base cred, with the security data derived from
+ * that; if this is "&init_task", they'll be set to 0, no groups, full
+ * capabilities, and no keys.
+ *
+ * The caller may change these controls afterwards if desired.
+ *
+ * Returns the new credentials or NULL if out of memory.
+ */
+struct cred *prepare_kernel_cred(struct task_struct *daemon)
+{
+	const struct cred *old;
+	struct cred *new;
+
+	if (WARN_ON_ONCE(!daemon))
+		return NULL;
+
+	new = kmem_cache_alloc(cred_jar, GFP_KERNEL);
+	if (!new)
+		return NULL;
+
+	kdebug("prepare_kernel_cred() alloc %p", new);
+
+	old = get_task_cred(daemon);
+	validate_creds(old);
+
+	*new = *old;
+	new->non_rcu = 0;
+	atomic_set(&new->usage, 1);
+	set_cred_subscribers(new, 0);
+	get_uid(new->user);
+	get_user_ns(new->user_ns);
+	get_group_info(new->group_info);
+
+#ifdef CONFIG_KEYS
+	new->session_keyring = NULL;
+	new->process_keyring = NULL;
+	new->thread_keyring = NULL;
+	new->request_key_auth = NULL;
+	new->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING;
+#endif
+
+#ifdef CONFIG_SECURITY
+	new->security = NULL;
+#endif
+	new->ucounts = get_ucounts(new->ucounts);
+	if (!new->ucounts)
+		goto error;
+
+	if (security_prepare_creds(new, old, GFP_KERNEL_ACCOUNT) < 0)
+		goto error;
+
+	put_cred(old);
+	validate_creds(new);
+	return new;
+
+error:
+	put_cred(new);
+	put_cred(old);
+	return NULL;
+}
+EXPORT_SYMBOL(prepare_kernel_cred);
+
+/**
+ * set_security_override - Set the security ID in a set of credentials
+ * @new: The credentials to alter
+ * @secid: The LSM security ID to set
+ *
+ * Set the LSM security ID in a set of credentials so that the subjective
+ * security is overridden when an alternative set of credentials is used.
+ */
+int set_security_override(struct cred *new, u32 secid)
+{
+	return security_kernel_act_as(new, secid);
+}
+EXPORT_SYMBOL(set_security_override);
+
+/**
+ * set_security_override_from_ctx - Set the security ID in a set of credentials
+ * @new: The credentials to alter
+ * @secctx: The LSM security context to generate the security ID from.
+ *
+ * Set the LSM security ID in a set of credentials so that the subjective
+ * security is overridden when an alternative set of credentials is used.  The
+ * security ID is specified in string form as a security context to be
+ * interpreted by the LSM.
+ */
+int set_security_override_from_ctx(struct cred *new, const char *secctx)
+{
+	u32 secid;
+	int ret;
+
+	ret = security_secctx_to_secid(secctx, strlen(secctx), &secid);
+	if (ret < 0)
+		return ret;
+
+	return set_security_override(new, secid);
+}
+EXPORT_SYMBOL(set_security_override_from_ctx);
+
+/**
+ * set_create_files_as - Set the LSM file create context in a set of credentials
+ * @new: The credentials to alter
+ * @inode: The inode to take the context from
+ *
+ * Change the LSM file creation context in a set of credentials to be the same
+ * as the object context of the specified inode, so that the new inodes have
+ * the same MAC context as that inode.
+ */
+int set_create_files_as(struct cred *new, struct inode *inode)
+{
+	if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid))
+		return -EINVAL;
+	new->fsuid = inode->i_uid;
+	new->fsgid = inode->i_gid;
+	return security_kernel_create_files_as(new, inode);
+}
+EXPORT_SYMBOL(set_create_files_as);
+
+#ifdef CONFIG_DEBUG_CREDENTIALS
+
+bool creds_are_invalid(const struct cred *cred)
+{
+	if (cred->magic != CRED_MAGIC)
+		return true;
+	return false;
+}
+EXPORT_SYMBOL(creds_are_invalid);
+
+/*
+ * dump invalid credentials
+ */
+static void dump_invalid_creds(const struct cred *cred, const char *label,
+			       const struct task_struct *tsk)
+{
+	printk(KERN_ERR "CRED: %s credentials: %p %s%s%s\n",
+	       label, cred,
+	       cred == &init_cred ? "[init]" : "",
+	       cred == tsk->real_cred ? "[real]" : "",
+	       cred == tsk->cred ? "[eff]" : "");
+	printk(KERN_ERR "CRED: ->magic=%x, put_addr=%p\n",
+	       cred->magic, cred->put_addr);
+	printk(KERN_ERR "CRED: ->usage=%d, subscr=%d\n",
+	       atomic_read(&cred->usage),
+	       read_cred_subscribers(cred));
+	printk(KERN_ERR "CRED: ->*uid = { %d,%d,%d,%d }\n",
+		from_kuid_munged(&init_user_ns, cred->uid),
+		from_kuid_munged(&init_user_ns, cred->euid),
+		from_kuid_munged(&init_user_ns, cred->suid),
+		from_kuid_munged(&init_user_ns, cred->fsuid));
+	printk(KERN_ERR "CRED: ->*gid = { %d,%d,%d,%d }\n",
+		from_kgid_munged(&init_user_ns, cred->gid),
+		from_kgid_munged(&init_user_ns, cred->egid),
+		from_kgid_munged(&init_user_ns, cred->sgid),
+		from_kgid_munged(&init_user_ns, cred->fsgid));
+#ifdef CONFIG_SECURITY
+	printk(KERN_ERR "CRED: ->security is %p\n", cred->security);
+	if ((unsigned long) cred->security >= PAGE_SIZE &&
+	    (((unsigned long) cred->security & 0xffffff00) !=
+	     (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8)))
+		printk(KERN_ERR "CRED: ->security {%x, %x}\n",
+		       ((u32*)cred->security)[0],
+		       ((u32*)cred->security)[1]);
+#endif
+}
+
+/*
+ * report use of invalid credentials
+ */
+void __noreturn __invalid_creds(const struct cred *cred, const char *file, unsigned line)
+{
+	printk(KERN_ERR "CRED: Invalid credentials\n");
+	printk(KERN_ERR "CRED: At %s:%u\n", file, line);
+	dump_invalid_creds(cred, "Specified", current);
+	BUG();
+}
+EXPORT_SYMBOL(__invalid_creds);
+
+/*
+ * check the credentials on a process
+ */
+void __validate_process_creds(struct task_struct *tsk,
+			      const char *file, unsigned line)
+{
+	if (tsk->cred == tsk->real_cred) {
+		if (unlikely(read_cred_subscribers(tsk->cred) < 2 ||
+			     creds_are_invalid(tsk->cred)))
+			goto invalid_creds;
+	} else {
+		if (unlikely(read_cred_subscribers(tsk->real_cred) < 1 ||
+			     read_cred_subscribers(tsk->cred) < 1 ||
+			     creds_are_invalid(tsk->real_cred) ||
+			     creds_are_invalid(tsk->cred)))
+			goto invalid_creds;
+	}
+	return;
+
+invalid_creds:
+	printk(KERN_ERR "CRED: Invalid process credentials\n");
+	printk(KERN_ERR "CRED: At %s:%u\n", file, line);
+
+	dump_invalid_creds(tsk->real_cred, "Real", tsk);
+	if (tsk->cred != tsk->real_cred)
+		dump_invalid_creds(tsk->cred, "Effective", tsk);
+	else
+		printk(KERN_ERR "CRED: Effective creds == Real creds\n");
+	BUG();
+}
+EXPORT_SYMBOL(__validate_process_creds);
+
+/*
+ * check creds for do_exit()
+ */
+void validate_creds_for_do_exit(struct task_struct *tsk)
+{
+	kdebug("validate_creds_for_do_exit(%p,%p{%d,%d})",
+	       tsk->real_cred, tsk->cred,
+	       atomic_read(&tsk->cred->usage),
+	       read_cred_subscribers(tsk->cred));
+
+	__validate_process_creds(tsk, __FILE__, __LINE__);
+}
+
+#endif /* CONFIG_DEBUG_CREDENTIALS */