diff options
Diffstat (limited to 'security/integrity/ima/ima_appraise.c')
| -rw-r--r-- | security/integrity/ima/ima_appraise.c | 285 |
1 files changed, 234 insertions, 51 deletions
diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c index 17232bbfb9f9..5149ff4fd50d 100644 --- a/security/integrity/ima/ima_appraise.c +++ b/security/integrity/ima/ima_appraise.c @@ -8,12 +8,15 @@ #include <linux/module.h> #include <linux/init.h> #include <linux/file.h> +#include <linux/binfmts.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" @@ -68,22 +71,21 @@ bool is_ima_appraise_enabled(void) * * Return 1 to appraise or hash */ -int ima_must_appraise(struct user_namespace *mnt_userns, struct inode *inode, +int ima_must_appraise(struct mnt_idmap *idmap, struct inode *inode, int mask, enum ima_hooks func) { - u32 secid; + struct lsm_prop prop; if (!ima_appraise) return 0; - security_current_getsecid_subj(&secid); - return ima_match_policy(mnt_userns, inode, current_cred(), secid, + security_current_getlsmprop_subj(&prop); + return ima_match_policy(idmap, inode, current_cred(), &prop, func, mask, IMA_APPRAISE | IMA_HASH, NULL, NULL, NULL, NULL); } -static int ima_fix_xattr(struct dentry *dentry, - struct integrity_iint_cache *iint) +static int ima_fix_xattr(struct dentry *dentry, struct ima_iint_cache *iint) { int rc, offset; u8 algo = iint->ima_hash->algo; @@ -96,7 +98,7 @@ static int ima_fix_xattr(struct dentry *dentry, iint->ima_hash->xattr.ng.type = IMA_XATTR_DIGEST_NG; iint->ima_hash->xattr.ng.algo = algo; } - rc = __vfs_setxattr_noperm(&init_user_ns, dentry, XATTR_NAME_IMA, + 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); @@ -104,11 +106,12 @@ static int ima_fix_xattr(struct dentry *dentry, } /* Return specific func appraised cached result */ -enum integrity_status ima_get_cache_status(struct integrity_iint_cache *iint, +enum integrity_status ima_get_cache_status(struct ima_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; @@ -123,12 +126,13 @@ enum integrity_status ima_get_cache_status(struct integrity_iint_cache *iint, } } -static void ima_set_cache_status(struct integrity_iint_cache *iint, +static void ima_set_cache_status(struct ima_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: @@ -148,11 +152,11 @@ static void ima_set_cache_status(struct integrity_iint_cache *iint, } } -static void ima_cache_flags(struct integrity_iint_cache *iint, - enum ima_hooks func) +static void ima_cache_flags(struct ima_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: @@ -183,13 +187,18 @@ enum hash_algo ima_get_hash_algo(const struct evm_ima_xattr_data *xattr_value, 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; - break; case IMA_XATTR_DIGEST_NG: /* first byte contains algorithm id */ ret = xattr_value->data[0]; @@ -214,29 +223,66 @@ enum hash_algo ima_get_hash_algo(const struct evm_ima_xattr_data *xattr_value, } int ima_read_xattr(struct dentry *dentry, - struct evm_ima_xattr_data **xattr_value) + struct evm_ima_xattr_data **xattr_value, int xattr_len) { - ssize_t ret; + int ret; - ret = vfs_getxattr_alloc(&init_user_ns, dentry, XATTR_NAME_IMA, - (char **)xattr_value, 0, GFP_NOFS); + 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, +static int xattr_verify(enum ima_hooks func, struct ima_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: @@ -246,7 +292,10 @@ static int xattr_verify(enum ima_hooks func, struct integrity_iint_cache *iint, case IMA_XATTR_DIGEST: if (*status != INTEGRITY_PASS_IMMUTABLE) { if (iint->flags & IMA_DIGSIG_REQUIRED) { - *cause = "IMA-signature-required"; + if (iint->flags & IMA_VERITY_REQUIRED) + *cause = "verity-signature-required"; + else + *cause = "IMA-signature-required"; *status = INTEGRITY_FAIL; break; } @@ -274,6 +323,20 @@ static int xattr_verify(enum ima_hooks func, struct integrity_iint_cache *iint, 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, @@ -297,6 +360,46 @@ static int xattr_verify(enum ima_hooks func, struct integrity_iint_cache *iint, *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, + container_of(&hash.hdr, + struct ima_digest_data, 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"; @@ -341,7 +444,7 @@ static int modsig_verify(enum ima_hooks func, const struct modsig *modsig, * * Returns -EPERM if the hash is blacklisted. */ -int ima_check_blacklist(struct integrity_iint_cache *iint, +int ima_check_blacklist(struct ima_iint_cache *iint, const struct modsig *modsig, int pcr) { enum hash_algo hash_algo; @@ -356,15 +459,28 @@ int ima_check_blacklist(struct integrity_iint_cache *iint, 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(&init_user_ns, NULL, digest, digestsize, - "blacklisted-hash", NONE, - pcr, NULL, false, NULL, 0); - } + } 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; } +static bool is_bprm_creds_for_exec(enum ima_hooks func, struct file *file) +{ + struct linux_binprm *bprm; + + if (func == BPRM_CHECK) { + bprm = container_of(&file, struct linux_binprm, file); + return bprm->is_check; + } + return false; +} + /* * ima_appraise_measurement - appraise file measurement * @@ -373,13 +489,13 @@ int ima_check_blacklist(struct integrity_iint_cache *iint, * * Return 0 on success, error code otherwise */ -int ima_appraise_measurement(enum ima_hooks func, - struct integrity_iint_cache *iint, +int ima_appraise_measurement(enum ima_hooks func, struct ima_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"; + int audit_msgno = AUDIT_INTEGRITY_DATA; const char *cause = "unknown"; struct dentry *dentry = file_dentry(file); struct inode *inode = d_backing_inode(dentry); @@ -391,13 +507,30 @@ int ima_appraise_measurement(enum ima_hooks func, if (!(inode->i_opflags & IOP_XATTR) && !try_modsig) return INTEGRITY_UNKNOWN; + /* + * Unlike any of the other LSM hooks where the kernel enforces file + * integrity, enforcing file integrity for the bprm_creds_for_exec() + * LSM hook with the AT_EXECVE_CHECK flag is left up to the discretion + * of the script interpreter(userspace). Differentiate kernel and + * userspace enforced integrity audit messages. + */ + if (is_bprm_creds_for_exec(func, file)) + audit_msgno = AUDIT_INTEGRITY_USERSPACE; + /* If reading the xattr failed and there's no modsig, error out. */ if (rc <= 0 && !try_modsig) { if (rc && rc != -ENODATA) goto out; - cause = iint->flags & IMA_DIGSIG_REQUIRED ? - "IMA-signature-required" : "missing-hash"; + 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; @@ -408,7 +541,8 @@ int ima_appraise_measurement(enum ima_hooks func, goto out; } - status = evm_verifyxattr(dentry, XATTR_NAME_IMA, xattr_value, rc, iint); + status = evm_verifyxattr(dentry, XATTR_NAME_IMA, xattr_value, + rc < 0 ? 0 : rc); switch (status) { case INTEGRITY_PASS: case INTEGRITY_PASS_IMMUTABLE: @@ -458,7 +592,7 @@ out: (iint->flags & IMA_FAIL_UNVERIFIABLE_SIGS))) { status = INTEGRITY_FAIL; cause = "unverifiable-signature"; - integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, filename, + integrity_audit_msg(audit_msgno, inode, filename, op, cause, rc, 0); } else if (status != INTEGRITY_PASS) { /* Fix mode, but don't replace file signatures. */ @@ -478,7 +612,7 @@ out: status = INTEGRITY_PASS; } - integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, filename, + integrity_audit_msg(audit_msgno, inode, filename, op, cause, rc, 0); } else { ima_cache_flags(iint, func); @@ -491,7 +625,7 @@ out: /* * ima_update_xattr - update 'security.ima' hash value */ -void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file) +void ima_update_xattr(struct ima_iint_cache *iint, struct file *file) { struct dentry *dentry = file_dentry(file); int rc = 0; @@ -515,27 +649,28 @@ void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file) /** * ima_inode_post_setattr - reflect file metadata changes - * @mnt_userns: user namespace of the mount the inode was found from + * @idmap: idmap of the mount the inode was found from * @dentry: pointer to the affected dentry + * @ia_valid: for the UID and GID status * * 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 user_namespace *mnt_userns, - struct dentry *dentry) +static void ima_inode_post_setattr(struct mnt_idmap *idmap, + struct dentry *dentry, int ia_valid) { struct inode *inode = d_backing_inode(dentry); - struct integrity_iint_cache *iint; + struct ima_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(mnt_userns, inode, MAY_ACCESS, POST_SETATTR); - iint = integrity_iint_find(inode); + action = ima_must_appraise(idmap, inode, MAY_ACCESS, POST_SETATTR); + iint = ima_iint_find(inode); if (iint) { set_bit(IMA_CHANGE_ATTR, &iint->atomic_flags); if (!action) @@ -559,21 +694,30 @@ static int ima_protect_xattr(struct dentry *dentry, const char *xattr_name, return 0; } +/* + * ima_reset_appraise_flags - reset ima_iint_cache flags + * + * @digsig: whether to clear/set IMA_DIGSIG flag, tristate values + * 0: clear IMA_DIGSIG + * 1: set IMA_DIGSIG + * -1: don't change IMA_DIGSIG + * + */ static void ima_reset_appraise_flags(struct inode *inode, int digsig) { - struct integrity_iint_cache *iint; + struct ima_iint_cache *iint; if (!(ima_policy_flag & IMA_APPRAISE) || !S_ISREG(inode->i_mode)) return; - iint = integrity_iint_find(inode); + iint = ima_iint_find(inode); if (!iint) return; iint->measured_pcrs = 0; set_bit(IMA_CHANGE_XATTR, &iint->atomic_flags); - if (digsig) + if (digsig == 1) set_bit(IMA_DIGSIG, &iint->atomic_flags); - else + else if (digsig == 0) clear_bit(IMA_DIGSIG, &iint->atomic_flags); } @@ -637,41 +781,80 @@ static int validate_hash_algo(struct dentry *dentry, return -EACCES; } -int ima_inode_setxattr(struct dentry *dentry, const char *xattr_name, - const void *xattr_value, size_t xattr_value_len) +static int ima_inode_setxattr(struct mnt_idmap *idmap, struct dentry *dentry, + const char *xattr_name, const void *xattr_value, + size_t xattr_value_len, int flags) { 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); + } else { + digsig = -1; } if (result == 1 || evm_revalidate_status(xattr_name)) { - result = validate_hash_algo(dentry, xvalue, xattr_value_len); - if (result) - return result; - ima_reset_appraise_flags(d_backing_inode(dentry), digsig); + if (result == 1) + result = 0; } return result; } -int ima_inode_removexattr(struct dentry *dentry, const char *xattr_name) +static int ima_inode_set_acl(struct mnt_idmap *idmap, struct dentry *dentry, + const char *acl_name, struct posix_acl *kacl) { - int result; + if (evm_revalidate_status(acl_name)) + ima_reset_appraise_flags(d_backing_inode(dentry), -1); + + return 0; +} + +static int ima_inode_removexattr(struct mnt_idmap *idmap, struct dentry *dentry, + const char *xattr_name) +{ + int result, digsig = -1; 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 (!strcmp(xattr_name, XATTR_NAME_IMA)) + digsig = 0; + ima_reset_appraise_flags(d_backing_inode(dentry), digsig); if (result == 1) result = 0; } return result; } + +static int ima_inode_remove_acl(struct mnt_idmap *idmap, struct dentry *dentry, + const char *acl_name) +{ + return ima_inode_set_acl(idmap, dentry, acl_name, NULL); +} + +static struct security_hook_list ima_appraise_hooks[] __ro_after_init = { + LSM_HOOK_INIT(inode_post_setattr, ima_inode_post_setattr), + LSM_HOOK_INIT(inode_setxattr, ima_inode_setxattr), + LSM_HOOK_INIT(inode_set_acl, ima_inode_set_acl), + LSM_HOOK_INIT(inode_removexattr, ima_inode_removexattr), + LSM_HOOK_INIT(inode_remove_acl, ima_inode_remove_acl), +}; + +void __init init_ima_appraise_lsm(const struct lsm_id *lsmid) +{ + security_add_hooks(ima_appraise_hooks, ARRAY_SIZE(ima_appraise_hooks), + lsmid); +} |