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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 /security/integrity/ima/ima_appraise.c
downloadlinux-5b7c4cabbb65f5c469464da6c5f614cbd7f730f2.tar.gz
linux-5b7c4cabbb65f5c469464da6c5f614cbd7f730f2.zip
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 'security/integrity/ima/ima_appraise.c')
-rw-r--r--security/integrity/ima/ima_appraise.c797
1 files changed, 797 insertions, 0 deletions
diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
new file mode 100644
index 000000000..555342d33
--- /dev/null
+++ b/security/integrity/ima/ima_appraise.c
@@ -0,0 +1,797 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2011 IBM Corporation
+ *
+ * Author:
+ * Mimi Zohar <zohar@us.ibm.com>
+ */
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/xattr.h>
+#include <linux/magic.h>
+#include <linux/ima.h>
+#include <linux/evm.h>
+#include <linux/fsverity.h>
+#include <keys/system_keyring.h>
+#include <uapi/linux/fsverity.h>
+
+#include "ima.h"
+
+#ifdef CONFIG_IMA_APPRAISE_BOOTPARAM
+static char *ima_appraise_cmdline_default __initdata;
+core_param(ima_appraise, ima_appraise_cmdline_default, charp, 0);
+
+void __init ima_appraise_parse_cmdline(void)
+{
+ const char *str = ima_appraise_cmdline_default;
+ bool sb_state = arch_ima_get_secureboot();
+ int appraisal_state = ima_appraise;
+
+ if (!str)
+ return;
+
+ if (strncmp(str, "off", 3) == 0)
+ appraisal_state = 0;
+ else if (strncmp(str, "log", 3) == 0)
+ appraisal_state = IMA_APPRAISE_LOG;
+ else if (strncmp(str, "fix", 3) == 0)
+ appraisal_state = IMA_APPRAISE_FIX;
+ else if (strncmp(str, "enforce", 7) == 0)
+ appraisal_state = IMA_APPRAISE_ENFORCE;
+ else
+ pr_err("invalid \"%s\" appraise option", str);
+
+ /* If appraisal state was changed, but secure boot is enabled,
+ * keep its default */
+ if (sb_state) {
+ if (!(appraisal_state & IMA_APPRAISE_ENFORCE))
+ pr_info("Secure boot enabled: ignoring ima_appraise=%s option",
+ str);
+ } else {
+ ima_appraise = appraisal_state;
+ }
+}
+#endif
+
+/*
+ * is_ima_appraise_enabled - return appraise status
+ *
+ * Only return enabled, if not in ima_appraise="fix" or "log" modes.
+ */
+bool is_ima_appraise_enabled(void)
+{
+ return ima_appraise & IMA_APPRAISE_ENFORCE;
+}
+
+/*
+ * ima_must_appraise - set appraise flag
+ *
+ * Return 1 to appraise or hash
+ */
+int ima_must_appraise(struct mnt_idmap *idmap, struct inode *inode,
+ int mask, enum ima_hooks func)
+{
+ u32 secid;
+
+ if (!ima_appraise)
+ return 0;
+
+ security_current_getsecid_subj(&secid);
+ return ima_match_policy(idmap, inode, current_cred(), secid,
+ func, mask, IMA_APPRAISE | IMA_HASH, NULL,
+ NULL, NULL, NULL);
+}
+
+static int ima_fix_xattr(struct dentry *dentry,
+ struct integrity_iint_cache *iint)
+{
+ int rc, offset;
+ u8 algo = iint->ima_hash->algo;
+
+ if (algo <= HASH_ALGO_SHA1) {
+ offset = 1;
+ iint->ima_hash->xattr.sha1.type = IMA_XATTR_DIGEST;
+ } else {
+ offset = 0;
+ iint->ima_hash->xattr.ng.type = IMA_XATTR_DIGEST_NG;
+ iint->ima_hash->xattr.ng.algo = algo;
+ }
+ rc = __vfs_setxattr_noperm(&nop_mnt_idmap, dentry, XATTR_NAME_IMA,
+ &iint->ima_hash->xattr.data[offset],
+ (sizeof(iint->ima_hash->xattr) - offset) +
+ iint->ima_hash->length, 0);
+ return rc;
+}
+
+/* Return specific func appraised cached result */
+enum integrity_status ima_get_cache_status(struct integrity_iint_cache *iint,
+ enum ima_hooks func)
+{
+ switch (func) {
+ case MMAP_CHECK:
+ return iint->ima_mmap_status;
+ case BPRM_CHECK:
+ return iint->ima_bprm_status;
+ case CREDS_CHECK:
+ return iint->ima_creds_status;
+ case FILE_CHECK:
+ case POST_SETATTR:
+ return iint->ima_file_status;
+ case MODULE_CHECK ... MAX_CHECK - 1:
+ default:
+ return iint->ima_read_status;
+ }
+}
+
+static void ima_set_cache_status(struct integrity_iint_cache *iint,
+ enum ima_hooks func,
+ enum integrity_status status)
+{
+ switch (func) {
+ case MMAP_CHECK:
+ iint->ima_mmap_status = status;
+ break;
+ case BPRM_CHECK:
+ iint->ima_bprm_status = status;
+ break;
+ case CREDS_CHECK:
+ iint->ima_creds_status = status;
+ break;
+ case FILE_CHECK:
+ case POST_SETATTR:
+ iint->ima_file_status = status;
+ break;
+ case MODULE_CHECK ... MAX_CHECK - 1:
+ default:
+ iint->ima_read_status = status;
+ break;
+ }
+}
+
+static void ima_cache_flags(struct integrity_iint_cache *iint,
+ enum ima_hooks func)
+{
+ switch (func) {
+ case MMAP_CHECK:
+ iint->flags |= (IMA_MMAP_APPRAISED | IMA_APPRAISED);
+ break;
+ case BPRM_CHECK:
+ iint->flags |= (IMA_BPRM_APPRAISED | IMA_APPRAISED);
+ break;
+ case CREDS_CHECK:
+ iint->flags |= (IMA_CREDS_APPRAISED | IMA_APPRAISED);
+ break;
+ case FILE_CHECK:
+ case POST_SETATTR:
+ iint->flags |= (IMA_FILE_APPRAISED | IMA_APPRAISED);
+ break;
+ case MODULE_CHECK ... MAX_CHECK - 1:
+ default:
+ iint->flags |= (IMA_READ_APPRAISED | IMA_APPRAISED);
+ break;
+ }
+}
+
+enum hash_algo ima_get_hash_algo(const struct evm_ima_xattr_data *xattr_value,
+ int xattr_len)
+{
+ struct signature_v2_hdr *sig;
+ enum hash_algo ret;
+
+ if (!xattr_value || xattr_len < 2)
+ /* return default hash algo */
+ return ima_hash_algo;
+
+ switch (xattr_value->type) {
+ case IMA_VERITY_DIGSIG:
+ sig = (typeof(sig))xattr_value;
+ if (sig->version != 3 || xattr_len <= sizeof(*sig) ||
+ sig->hash_algo >= HASH_ALGO__LAST)
+ return ima_hash_algo;
+ return sig->hash_algo;
+ case EVM_IMA_XATTR_DIGSIG:
+ sig = (typeof(sig))xattr_value;
+ if (sig->version != 2 || xattr_len <= sizeof(*sig)
+ || sig->hash_algo >= HASH_ALGO__LAST)
+ return ima_hash_algo;
+ return sig->hash_algo;
+ case IMA_XATTR_DIGEST_NG:
+ /* first byte contains algorithm id */
+ ret = xattr_value->data[0];
+ if (ret < HASH_ALGO__LAST)
+ return ret;
+ break;
+ case IMA_XATTR_DIGEST:
+ /* this is for backward compatibility */
+ if (xattr_len == 21) {
+ unsigned int zero = 0;
+ if (!memcmp(&xattr_value->data[16], &zero, 4))
+ return HASH_ALGO_MD5;
+ else
+ return HASH_ALGO_SHA1;
+ } else if (xattr_len == 17)
+ return HASH_ALGO_MD5;
+ break;
+ }
+
+ /* return default hash algo */
+ return ima_hash_algo;
+}
+
+int ima_read_xattr(struct dentry *dentry,
+ struct evm_ima_xattr_data **xattr_value, int xattr_len)
+{
+ int ret;
+
+ ret = vfs_getxattr_alloc(&nop_mnt_idmap, dentry, XATTR_NAME_IMA,
+ (char **)xattr_value, xattr_len, GFP_NOFS);
+ if (ret == -EOPNOTSUPP)
+ ret = 0;
+ return ret;
+}
+
+/*
+ * calc_file_id_hash - calculate the hash of the ima_file_id struct data
+ * @type: xattr type [enum evm_ima_xattr_type]
+ * @algo: hash algorithm [enum hash_algo]
+ * @digest: pointer to the digest to be hashed
+ * @hash: (out) pointer to the hash
+ *
+ * IMA signature version 3 disambiguates the data that is signed by
+ * indirectly signing the hash of the ima_file_id structure data.
+ *
+ * Signing the ima_file_id struct is currently only supported for
+ * IMA_VERITY_DIGSIG type xattrs.
+ *
+ * Return 0 on success, error code otherwise.
+ */
+static int calc_file_id_hash(enum evm_ima_xattr_type type,
+ enum hash_algo algo, const u8 *digest,
+ struct ima_digest_data *hash)
+{
+ struct ima_file_id file_id = {
+ .hash_type = IMA_VERITY_DIGSIG, .hash_algorithm = algo};
+ unsigned int unused = HASH_MAX_DIGESTSIZE - hash_digest_size[algo];
+
+ if (type != IMA_VERITY_DIGSIG)
+ return -EINVAL;
+
+ memcpy(file_id.hash, digest, hash_digest_size[algo]);
+
+ hash->algo = algo;
+ hash->length = hash_digest_size[algo];
+
+ return ima_calc_buffer_hash(&file_id, sizeof(file_id) - unused, hash);
+}
+
+/*
+ * xattr_verify - verify xattr digest or signature
+ *
+ * Verify whether the hash or signature matches the file contents.
+ *
+ * Return 0 on success, error code otherwise.
+ */
+static int xattr_verify(enum ima_hooks func, struct integrity_iint_cache *iint,
+ struct evm_ima_xattr_data *xattr_value, int xattr_len,
+ enum integrity_status *status, const char **cause)
+{
+ struct ima_max_digest_data hash;
+ struct signature_v2_hdr *sig;
+ int rc = -EINVAL, hash_start = 0;
+ int mask;
+
+ switch (xattr_value->type) {
+ case IMA_XATTR_DIGEST_NG:
+ /* first byte contains algorithm id */
+ hash_start = 1;
+ fallthrough;
+ case IMA_XATTR_DIGEST:
+ if (*status != INTEGRITY_PASS_IMMUTABLE) {
+ if (iint->flags & IMA_DIGSIG_REQUIRED) {
+ if (iint->flags & IMA_VERITY_REQUIRED)
+ *cause = "verity-signature-required";
+ else
+ *cause = "IMA-signature-required";
+ *status = INTEGRITY_FAIL;
+ break;
+ }
+ clear_bit(IMA_DIGSIG, &iint->atomic_flags);
+ } else {
+ set_bit(IMA_DIGSIG, &iint->atomic_flags);
+ }
+ if (xattr_len - sizeof(xattr_value->type) - hash_start >=
+ iint->ima_hash->length)
+ /*
+ * xattr length may be longer. md5 hash in previous
+ * version occupied 20 bytes in xattr, instead of 16
+ */
+ rc = memcmp(&xattr_value->data[hash_start],
+ iint->ima_hash->digest,
+ iint->ima_hash->length);
+ else
+ rc = -EINVAL;
+ if (rc) {
+ *cause = "invalid-hash";
+ *status = INTEGRITY_FAIL;
+ break;
+ }
+ *status = INTEGRITY_PASS;
+ break;
+ case EVM_IMA_XATTR_DIGSIG:
+ set_bit(IMA_DIGSIG, &iint->atomic_flags);
+
+ mask = IMA_DIGSIG_REQUIRED | IMA_VERITY_REQUIRED;
+ if ((iint->flags & mask) == mask) {
+ *cause = "verity-signature-required";
+ *status = INTEGRITY_FAIL;
+ break;
+ }
+
+ sig = (typeof(sig))xattr_value;
+ if (sig->version >= 3) {
+ *cause = "invalid-signature-version";
+ *status = INTEGRITY_FAIL;
+ break;
+ }
+ rc = integrity_digsig_verify(INTEGRITY_KEYRING_IMA,
+ (const char *)xattr_value,
+ xattr_len,
+ iint->ima_hash->digest,
+ iint->ima_hash->length);
+ if (rc == -EOPNOTSUPP) {
+ *status = INTEGRITY_UNKNOWN;
+ break;
+ }
+ if (IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING) && rc &&
+ func == KEXEC_KERNEL_CHECK)
+ rc = integrity_digsig_verify(INTEGRITY_KEYRING_PLATFORM,
+ (const char *)xattr_value,
+ xattr_len,
+ iint->ima_hash->digest,
+ iint->ima_hash->length);
+ if (rc) {
+ *cause = "invalid-signature";
+ *status = INTEGRITY_FAIL;
+ } else {
+ *status = INTEGRITY_PASS;
+ }
+ break;
+ case IMA_VERITY_DIGSIG:
+ set_bit(IMA_DIGSIG, &iint->atomic_flags);
+
+ if (iint->flags & IMA_DIGSIG_REQUIRED) {
+ if (!(iint->flags & IMA_VERITY_REQUIRED)) {
+ *cause = "IMA-signature-required";
+ *status = INTEGRITY_FAIL;
+ break;
+ }
+ }
+
+ sig = (typeof(sig))xattr_value;
+ if (sig->version != 3) {
+ *cause = "invalid-signature-version";
+ *status = INTEGRITY_FAIL;
+ break;
+ }
+
+ rc = calc_file_id_hash(IMA_VERITY_DIGSIG, iint->ima_hash->algo,
+ iint->ima_hash->digest, &hash.hdr);
+ if (rc) {
+ *cause = "sigv3-hashing-error";
+ *status = INTEGRITY_FAIL;
+ break;
+ }
+
+ rc = integrity_digsig_verify(INTEGRITY_KEYRING_IMA,
+ (const char *)xattr_value,
+ xattr_len, hash.digest,
+ hash.hdr.length);
+ if (rc) {
+ *cause = "invalid-verity-signature";
+ *status = INTEGRITY_FAIL;
+ } else {
+ *status = INTEGRITY_PASS;
+ }
+
+ break;
+ default:
+ *status = INTEGRITY_UNKNOWN;
+ *cause = "unknown-ima-data";
+ break;
+ }
+
+ return rc;
+}
+
+/*
+ * modsig_verify - verify modsig signature
+ *
+ * Verify whether the signature matches the file contents.
+ *
+ * Return 0 on success, error code otherwise.
+ */
+static int modsig_verify(enum ima_hooks func, const struct modsig *modsig,
+ enum integrity_status *status, const char **cause)
+{
+ int rc;
+
+ rc = integrity_modsig_verify(INTEGRITY_KEYRING_IMA, modsig);
+ if (IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING) && rc &&
+ func == KEXEC_KERNEL_CHECK)
+ rc = integrity_modsig_verify(INTEGRITY_KEYRING_PLATFORM,
+ modsig);
+ if (rc) {
+ *cause = "invalid-signature";
+ *status = INTEGRITY_FAIL;
+ } else {
+ *status = INTEGRITY_PASS;
+ }
+
+ return rc;
+}
+
+/*
+ * ima_check_blacklist - determine if the binary is blacklisted.
+ *
+ * Add the hash of the blacklisted binary to the measurement list, based
+ * on policy.
+ *
+ * Returns -EPERM if the hash is blacklisted.
+ */
+int ima_check_blacklist(struct integrity_iint_cache *iint,
+ const struct modsig *modsig, int pcr)
+{
+ enum hash_algo hash_algo;
+ const u8 *digest = NULL;
+ u32 digestsize = 0;
+ int rc = 0;
+
+ if (!(iint->flags & IMA_CHECK_BLACKLIST))
+ return 0;
+
+ if (iint->flags & IMA_MODSIG_ALLOWED && modsig) {
+ ima_get_modsig_digest(modsig, &hash_algo, &digest, &digestsize);
+
+ rc = is_binary_blacklisted(digest, digestsize);
+ if ((rc == -EPERM) && (iint->flags & IMA_MEASURE))
+ process_buffer_measurement(&nop_mnt_idmap, NULL, digest, digestsize,
+ "blacklisted-hash", NONE,
+ pcr, NULL, false, NULL, 0);
+ }
+
+ return rc;
+}
+
+/*
+ * ima_appraise_measurement - appraise file measurement
+ *
+ * Call evm_verifyxattr() to verify the integrity of 'security.ima'.
+ * Assuming success, compare the xattr hash with the collected measurement.
+ *
+ * Return 0 on success, error code otherwise
+ */
+int ima_appraise_measurement(enum ima_hooks func,
+ struct integrity_iint_cache *iint,
+ struct file *file, const unsigned char *filename,
+ struct evm_ima_xattr_data *xattr_value,
+ int xattr_len, const struct modsig *modsig)
+{
+ static const char op[] = "appraise_data";
+ const char *cause = "unknown";
+ struct dentry *dentry = file_dentry(file);
+ struct inode *inode = d_backing_inode(dentry);
+ enum integrity_status status = INTEGRITY_UNKNOWN;
+ int rc = xattr_len;
+ bool try_modsig = iint->flags & IMA_MODSIG_ALLOWED && modsig;
+
+ /* If not appraising a modsig, we need an xattr. */
+ if (!(inode->i_opflags & IOP_XATTR) && !try_modsig)
+ return INTEGRITY_UNKNOWN;
+
+ /* If reading the xattr failed and there's no modsig, error out. */
+ if (rc <= 0 && !try_modsig) {
+ if (rc && rc != -ENODATA)
+ goto out;
+
+ if (iint->flags & IMA_DIGSIG_REQUIRED) {
+ if (iint->flags & IMA_VERITY_REQUIRED)
+ cause = "verity-signature-required";
+ else
+ cause = "IMA-signature-required";
+ } else {
+ cause = "missing-hash";
+ }
+
+ status = INTEGRITY_NOLABEL;
+ if (file->f_mode & FMODE_CREATED)
+ iint->flags |= IMA_NEW_FILE;
+ if ((iint->flags & IMA_NEW_FILE) &&
+ (!(iint->flags & IMA_DIGSIG_REQUIRED) ||
+ (inode->i_size == 0)))
+ status = INTEGRITY_PASS;
+ goto out;
+ }
+
+ status = evm_verifyxattr(dentry, XATTR_NAME_IMA, xattr_value,
+ rc < 0 ? 0 : rc, iint);
+ switch (status) {
+ case INTEGRITY_PASS:
+ case INTEGRITY_PASS_IMMUTABLE:
+ case INTEGRITY_UNKNOWN:
+ break;
+ case INTEGRITY_NOXATTRS: /* No EVM protected xattrs. */
+ /* It's fine not to have xattrs when using a modsig. */
+ if (try_modsig)
+ break;
+ fallthrough;
+ case INTEGRITY_NOLABEL: /* No security.evm xattr. */
+ cause = "missing-HMAC";
+ goto out;
+ case INTEGRITY_FAIL_IMMUTABLE:
+ set_bit(IMA_DIGSIG, &iint->atomic_flags);
+ cause = "invalid-fail-immutable";
+ goto out;
+ case INTEGRITY_FAIL: /* Invalid HMAC/signature. */
+ cause = "invalid-HMAC";
+ goto out;
+ default:
+ WARN_ONCE(true, "Unexpected integrity status %d\n", status);
+ }
+
+ if (xattr_value)
+ rc = xattr_verify(func, iint, xattr_value, xattr_len, &status,
+ &cause);
+
+ /*
+ * If we have a modsig and either no imasig or the imasig's key isn't
+ * known, then try verifying the modsig.
+ */
+ if (try_modsig &&
+ (!xattr_value || xattr_value->type == IMA_XATTR_DIGEST_NG ||
+ rc == -ENOKEY))
+ rc = modsig_verify(func, modsig, &status, &cause);
+
+out:
+ /*
+ * File signatures on some filesystems can not be properly verified.
+ * When such filesystems are mounted by an untrusted mounter or on a
+ * system not willing to accept such a risk, fail the file signature
+ * verification.
+ */
+ if ((inode->i_sb->s_iflags & SB_I_IMA_UNVERIFIABLE_SIGNATURE) &&
+ ((inode->i_sb->s_iflags & SB_I_UNTRUSTED_MOUNTER) ||
+ (iint->flags & IMA_FAIL_UNVERIFIABLE_SIGS))) {
+ status = INTEGRITY_FAIL;
+ cause = "unverifiable-signature";
+ integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, filename,
+ op, cause, rc, 0);
+ } else if (status != INTEGRITY_PASS) {
+ /* Fix mode, but don't replace file signatures. */
+ if ((ima_appraise & IMA_APPRAISE_FIX) && !try_modsig &&
+ (!xattr_value ||
+ xattr_value->type != EVM_IMA_XATTR_DIGSIG)) {
+ if (!ima_fix_xattr(dentry, iint))
+ status = INTEGRITY_PASS;
+ }
+
+ /*
+ * Permit new files with file/EVM portable signatures, but
+ * without data.
+ */
+ if (inode->i_size == 0 && iint->flags & IMA_NEW_FILE &&
+ test_bit(IMA_DIGSIG, &iint->atomic_flags)) {
+ status = INTEGRITY_PASS;
+ }
+
+ integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, filename,
+ op, cause, rc, 0);
+ } else {
+ ima_cache_flags(iint, func);
+ }
+
+ ima_set_cache_status(iint, func, status);
+ return status;
+}
+
+/*
+ * ima_update_xattr - update 'security.ima' hash value
+ */
+void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file)
+{
+ struct dentry *dentry = file_dentry(file);
+ int rc = 0;
+
+ /* do not collect and update hash for digital signatures */
+ if (test_bit(IMA_DIGSIG, &iint->atomic_flags))
+ return;
+
+ if ((iint->ima_file_status != INTEGRITY_PASS) &&
+ !(iint->flags & IMA_HASH))
+ return;
+
+ rc = ima_collect_measurement(iint, file, NULL, 0, ima_hash_algo, NULL);
+ if (rc < 0)
+ return;
+
+ inode_lock(file_inode(file));
+ ima_fix_xattr(dentry, iint);
+ inode_unlock(file_inode(file));
+}
+
+/**
+ * ima_inode_post_setattr - reflect file metadata changes
+ * @idmap: idmap of the mount the inode was found from
+ * @dentry: pointer to the affected dentry
+ *
+ * Changes to a dentry's metadata might result in needing to appraise.
+ *
+ * This function is called from notify_change(), which expects the caller
+ * to lock the inode's i_mutex.
+ */
+void ima_inode_post_setattr(struct mnt_idmap *idmap,
+ struct dentry *dentry)
+{
+ struct inode *inode = d_backing_inode(dentry);
+ struct integrity_iint_cache *iint;
+ int action;
+
+ if (!(ima_policy_flag & IMA_APPRAISE) || !S_ISREG(inode->i_mode)
+ || !(inode->i_opflags & IOP_XATTR))
+ return;
+
+ action = ima_must_appraise(idmap, inode, MAY_ACCESS, POST_SETATTR);
+ iint = integrity_iint_find(inode);
+ if (iint) {
+ set_bit(IMA_CHANGE_ATTR, &iint->atomic_flags);
+ if (!action)
+ clear_bit(IMA_UPDATE_XATTR, &iint->atomic_flags);
+ }
+}
+
+/*
+ * ima_protect_xattr - protect 'security.ima'
+ *
+ * Ensure that not just anyone can modify or remove 'security.ima'.
+ */
+static int ima_protect_xattr(struct dentry *dentry, const char *xattr_name,
+ const void *xattr_value, size_t xattr_value_len)
+{
+ if (strcmp(xattr_name, XATTR_NAME_IMA) == 0) {
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+ return 1;
+ }
+ return 0;
+}
+
+static void ima_reset_appraise_flags(struct inode *inode, int digsig)
+{
+ struct integrity_iint_cache *iint;
+
+ if (!(ima_policy_flag & IMA_APPRAISE) || !S_ISREG(inode->i_mode))
+ return;
+
+ iint = integrity_iint_find(inode);
+ if (!iint)
+ return;
+ iint->measured_pcrs = 0;
+ set_bit(IMA_CHANGE_XATTR, &iint->atomic_flags);
+ if (digsig)
+ set_bit(IMA_DIGSIG, &iint->atomic_flags);
+ else
+ clear_bit(IMA_DIGSIG, &iint->atomic_flags);
+}
+
+/**
+ * validate_hash_algo() - Block setxattr with unsupported hash algorithms
+ * @dentry: object of the setxattr()
+ * @xattr_value: userland supplied xattr value
+ * @xattr_value_len: length of xattr_value
+ *
+ * The xattr value is mapped to its hash algorithm, and this algorithm
+ * must be built in the kernel for the setxattr to be allowed.
+ *
+ * Emit an audit message when the algorithm is invalid.
+ *
+ * Return: 0 on success, else an error.
+ */
+static int validate_hash_algo(struct dentry *dentry,
+ const struct evm_ima_xattr_data *xattr_value,
+ size_t xattr_value_len)
+{
+ char *path = NULL, *pathbuf = NULL;
+ enum hash_algo xattr_hash_algo;
+ const char *errmsg = "unavailable-hash-algorithm";
+ unsigned int allowed_hashes;
+
+ xattr_hash_algo = ima_get_hash_algo(xattr_value, xattr_value_len);
+
+ allowed_hashes = atomic_read(&ima_setxattr_allowed_hash_algorithms);
+
+ if (allowed_hashes) {
+ /* success if the algorithm is allowed in the ima policy */
+ if (allowed_hashes & (1U << xattr_hash_algo))
+ return 0;
+
+ /*
+ * We use a different audit message when the hash algorithm
+ * is denied by a policy rule, instead of not being built
+ * in the kernel image
+ */
+ errmsg = "denied-hash-algorithm";
+ } else {
+ if (likely(xattr_hash_algo == ima_hash_algo))
+ return 0;
+
+ /* allow any xattr using an algorithm built in the kernel */
+ if (crypto_has_alg(hash_algo_name[xattr_hash_algo], 0, 0))
+ return 0;
+ }
+
+ pathbuf = kmalloc(PATH_MAX, GFP_KERNEL);
+ if (!pathbuf)
+ return -EACCES;
+
+ path = dentry_path(dentry, pathbuf, PATH_MAX);
+
+ integrity_audit_msg(AUDIT_INTEGRITY_DATA, d_inode(dentry), path,
+ "set_data", errmsg, -EACCES, 0);
+
+ kfree(pathbuf);
+
+ return -EACCES;
+}
+
+int ima_inode_setxattr(struct dentry *dentry, const char *xattr_name,
+ const void *xattr_value, size_t xattr_value_len)
+{
+ const struct evm_ima_xattr_data *xvalue = xattr_value;
+ int digsig = 0;
+ int result;
+ int err;
+
+ result = ima_protect_xattr(dentry, xattr_name, xattr_value,
+ xattr_value_len);
+ if (result == 1) {
+ if (!xattr_value_len || (xvalue->type >= IMA_XATTR_LAST))
+ return -EINVAL;
+
+ err = validate_hash_algo(dentry, xvalue, xattr_value_len);
+ if (err)
+ return err;
+
+ digsig = (xvalue->type == EVM_IMA_XATTR_DIGSIG);
+ } else if (!strcmp(xattr_name, XATTR_NAME_EVM) && xattr_value_len > 0) {
+ digsig = (xvalue->type == EVM_XATTR_PORTABLE_DIGSIG);
+ }
+ if (result == 1 || evm_revalidate_status(xattr_name)) {
+ ima_reset_appraise_flags(d_backing_inode(dentry), digsig);
+ if (result == 1)
+ result = 0;
+ }
+ return result;
+}
+
+int ima_inode_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
+ const char *acl_name, struct posix_acl *kacl)
+{
+ if (evm_revalidate_status(acl_name))
+ ima_reset_appraise_flags(d_backing_inode(dentry), 0);
+
+ return 0;
+}
+
+int ima_inode_removexattr(struct dentry *dentry, const char *xattr_name)
+{
+ int result;
+
+ result = ima_protect_xattr(dentry, xattr_name, NULL, 0);
+ if (result == 1 || evm_revalidate_status(xattr_name)) {
+ ima_reset_appraise_flags(d_backing_inode(dentry), 0);
+ if (result == 1)
+ result = 0;
+ }
+ return result;
+}