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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
commitace9429bb58fd418f0c81d4c2835699bddf6bde6 (patch)
treeb2d64bc10158fdd5497876388cd68142ca374ed3 /security/integrity/ima/ima_appraise.c
parentInitial commit. (diff)
downloadlinux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.tar.xz
linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.zip
Adding upstream version 6.6.15.upstream/6.6.15
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'security/integrity/ima/ima_appraise.c')
-rw-r--r--security/integrity/ima/ima_appraise.c802
1 files changed, 802 insertions, 0 deletions
diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
new file mode 100644
index 0000000000..870dde6770
--- /dev/null
+++ b/security/integrity/ima/ima_appraise.c
@@ -0,0 +1,802 @@
+// 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:
+ case MMAP_CHECK_REQPROT:
+ 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:
+ case MMAP_CHECK_REQPROT:
+ 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:
+ case MMAP_CHECK_REQPROT:
+ 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);
+ } else if (iint->flags & IMA_DIGSIG_REQUIRED && iint->ima_hash)
+ rc = is_binary_blacklisted(iint->ima_hash->digest, iint->ima_hash->length);
+
+ 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;
+}