diff options
Diffstat (limited to 'security/integrity/ima/ima_main.c')
| -rw-r--r-- | security/integrity/ima/ima_main.c | 451 |
1 files changed, 380 insertions, 71 deletions
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index d7e987baf127..465865412100 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -15,11 +15,10 @@ * and ima_file_check. */ -#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt - #include <linux/module.h> #include <linux/file.h> #include <linux/binfmts.h> +#include <linux/kernel_read_file.h> #include <linux/mount.h> #include <linux/mman.h> #include <linux/slab.h> @@ -36,7 +35,7 @@ int ima_appraise = IMA_APPRAISE_ENFORCE; int ima_appraise; #endif -int ima_hash_algo = HASH_ALGO_SHA1; +int __ro_after_init ima_hash_algo = HASH_ALGO_SHA1; static int hash_setup_done; static struct notifier_block ima_lsm_policy_notifier = { @@ -52,18 +51,23 @@ static int __init hash_setup(char *str) return 1; if (strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) == 0) { - if (strncmp(str, "sha1", 4) == 0) + if (strncmp(str, "sha1", 4) == 0) { ima_hash_algo = HASH_ALGO_SHA1; - else if (strncmp(str, "md5", 3) == 0) + } else if (strncmp(str, "md5", 3) == 0) { ima_hash_algo = HASH_ALGO_MD5; - else + } else { + pr_err("invalid hash algorithm \"%s\" for template \"%s\"", + str, IMA_TEMPLATE_IMA_NAME); return 1; + } goto out; } i = match_string(hash_algo_name, HASH_ALGO__LAST, str); - if (i < 0) + if (i < 0) { + pr_err("invalid hash algorithm \"%s\"", str); return 1; + } ima_hash_algo = i; out: @@ -72,6 +76,11 @@ out: } __setup("ima_hash=", hash_setup); +enum hash_algo ima_get_current_hash_algo(void) +{ + return ima_hash_algo; +} + /* Prevent mmap'ing a file execute that is already mmap'ed write */ static int mmap_violation_check(enum ima_hooks func, struct file *file, char **pathbuf, const char **pathname, @@ -206,6 +215,7 @@ static int process_measurement(struct file *file, const struct cred *cred, int xattr_len = 0; bool violation_check; enum hash_algo hash_algo; + unsigned int allowed_algos = 0; if (!ima_policy_flag || !S_ISREG(inode->i_mode)) return 0; @@ -214,8 +224,9 @@ static int process_measurement(struct file *file, const struct cred *cred, * bitmask based on the appraise/audit/measurement policy. * Included is the appraise submask. */ - action = ima_get_action(inode, cred, secid, mask, func, &pcr, - &template_desc); + action = ima_get_action(file_mnt_user_ns(file), inode, cred, secid, + mask, func, &pcr, &template_desc, NULL, + &allowed_algos); violation_check = ((func == FILE_CHECK || func == MMAP_CHECK) && (ima_policy_flag & IMA_MEASURE)); if (!action && !violation_check) @@ -352,6 +363,16 @@ static int process_measurement(struct file *file, const struct cred *cred, if ((file->f_flags & O_DIRECT) && (iint->flags & IMA_PERMIT_DIRECTIO)) rc = 0; + + /* Ensure the digest was generated using an allowed algorithm */ + if (rc == 0 && must_appraise && allowed_algos != 0 && + (allowed_algos & (1U << hash_algo)) == 0) { + rc = -EACCES; + + integrity_audit_msg(AUDIT_INTEGRITY_DATA, file_inode(file), + pathname, "collect_data", + "denied-hash-algorithm", rc, 0); + } out_locked: if ((mask & MAY_WRITE) && test_bit(IMA_DIGSIG, &iint->atomic_flags) && !(iint->flags & IMA_NEW_FILE)) @@ -387,7 +408,7 @@ int ima_file_mmap(struct file *file, unsigned long prot) u32 secid; if (file && (prot & PROT_EXEC)) { - security_task_getsecid(current, &secid); + security_task_getsecid_subj(current, &secid); return process_measurement(file, current_cred(), secid, NULL, 0, MAY_EXEC, MMAP_CHECK); } @@ -396,6 +417,59 @@ int ima_file_mmap(struct file *file, unsigned long prot) } /** + * ima_file_mprotect - based on policy, limit mprotect change + * @prot: contains the protection that will be applied by the kernel. + * + * Files can be mmap'ed read/write and later changed to execute to circumvent + * IMA's mmap appraisal policy rules. Due to locking issues (mmap semaphore + * would be taken before i_mutex), files can not be measured or appraised at + * this point. Eliminate this integrity gap by denying the mprotect + * PROT_EXECUTE change, if an mmap appraise policy rule exists. + * + * On mprotect change success, return 0. On failure, return -EACESS. + */ +int ima_file_mprotect(struct vm_area_struct *vma, unsigned long prot) +{ + struct ima_template_desc *template = NULL; + struct file *file = vma->vm_file; + char filename[NAME_MAX]; + char *pathbuf = NULL; + const char *pathname = NULL; + struct inode *inode; + int result = 0; + int action; + u32 secid; + int pcr; + + /* Is mprotect making an mmap'ed file executable? */ + if (!(ima_policy_flag & IMA_APPRAISE) || !vma->vm_file || + !(prot & PROT_EXEC) || (vma->vm_flags & VM_EXEC)) + return 0; + + security_task_getsecid_subj(current, &secid); + inode = file_inode(vma->vm_file); + action = ima_get_action(file_mnt_user_ns(vma->vm_file), inode, + current_cred(), secid, MAY_EXEC, MMAP_CHECK, + &pcr, &template, NULL, NULL); + + /* Is the mmap'ed file in policy? */ + if (!(action & (IMA_MEASURE | IMA_APPRAISE_SUBMASK))) + return 0; + + if (action & IMA_APPRAISE_SUBMASK) + result = -EPERM; + + file = vma->vm_file; + pathname = ima_d_path(&file->f_path, &pathbuf, filename); + integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, pathname, + "collect_data", "failed-mprotect", result, 0); + if (pathbuf) + __putname(pathbuf); + + return result; +} + +/** * ima_bprm_check - based on policy, collect/store measurement. * @bprm: contains the linux_binprm structure * @@ -413,7 +487,7 @@ int ima_bprm_check(struct linux_binprm *bprm) int ret; u32 secid; - security_task_getsecid(current, &secid); + security_task_getsecid_subj(current, &secid); ret = process_measurement(bprm->file, current_cred(), secid, NULL, 0, MAY_EXEC, BPRM_CHECK); if (ret) @@ -425,7 +499,7 @@ int ima_bprm_check(struct linux_binprm *bprm) } /** - * ima_path_check - based on policy, collect/store measurement. + * ima_file_check - based on policy, collect/store measurement. * @file: pointer to the file to be measured * @mask: contains MAY_READ, MAY_WRITE, MAY_EXEC or MAY_APPEND * @@ -438,27 +512,122 @@ int ima_file_check(struct file *file, int mask) { u32 secid; - security_task_getsecid(current, &secid); + security_task_getsecid_subj(current, &secid); return process_measurement(file, current_cred(), secid, NULL, 0, mask & (MAY_READ | MAY_WRITE | MAY_EXEC | MAY_APPEND), FILE_CHECK); } EXPORT_SYMBOL_GPL(ima_file_check); +static int __ima_inode_hash(struct inode *inode, char *buf, size_t buf_size) +{ + struct integrity_iint_cache *iint; + int hash_algo; + + if (!ima_policy_flag) + return -EOPNOTSUPP; + + iint = integrity_iint_find(inode); + if (!iint) + return -EOPNOTSUPP; + + mutex_lock(&iint->mutex); + + /* + * ima_file_hash can be called when ima_collect_measurement has still + * not been called, we might not always have a hash. + */ + if (!iint->ima_hash) { + mutex_unlock(&iint->mutex); + return -EOPNOTSUPP; + } + + if (buf) { + size_t copied_size; + + copied_size = min_t(size_t, iint->ima_hash->length, buf_size); + memcpy(buf, iint->ima_hash->digest, copied_size); + } + hash_algo = iint->ima_hash->algo; + mutex_unlock(&iint->mutex); + + return hash_algo; +} + +/** + * ima_file_hash - return the stored measurement if a file has been hashed and + * is in the iint cache. + * @file: pointer to the file + * @buf: buffer in which to store the hash + * @buf_size: length of the buffer + * + * On success, return the hash algorithm (as defined in the enum hash_algo). + * If buf is not NULL, this function also outputs the hash into buf. + * If the hash is larger than buf_size, then only buf_size bytes will be copied. + * It generally just makes sense to pass a buffer capable of holding the largest + * possible hash: IMA_MAX_DIGEST_SIZE. + * The file hash returned is based on the entire file, including the appended + * signature. + * + * If IMA is disabled or if no measurement is available, return -EOPNOTSUPP. + * If the parameters are incorrect, return -EINVAL. + */ +int ima_file_hash(struct file *file, char *buf, size_t buf_size) +{ + if (!file) + return -EINVAL; + + return __ima_inode_hash(file_inode(file), buf, buf_size); +} +EXPORT_SYMBOL_GPL(ima_file_hash); + +/** + * ima_inode_hash - return the stored measurement if the inode has been hashed + * and is in the iint cache. + * @inode: pointer to the inode + * @buf: buffer in which to store the hash + * @buf_size: length of the buffer + * + * On success, return the hash algorithm (as defined in the enum hash_algo). + * If buf is not NULL, this function also outputs the hash into buf. + * If the hash is larger than buf_size, then only buf_size bytes will be copied. + * It generally just makes sense to pass a buffer capable of holding the largest + * possible hash: IMA_MAX_DIGEST_SIZE. + * The hash returned is based on the entire contents, including the appended + * signature. + * + * If IMA is disabled or if no measurement is available, return -EOPNOTSUPP. + * If the parameters are incorrect, return -EINVAL. + */ +int ima_inode_hash(struct inode *inode, char *buf, size_t buf_size) +{ + if (!inode) + return -EINVAL; + + return __ima_inode_hash(inode, buf, buf_size); +} +EXPORT_SYMBOL_GPL(ima_inode_hash); + /** * ima_post_create_tmpfile - mark newly created tmpfile as new + * @mnt_userns: user namespace of the mount the inode was found from * @file : newly created tmpfile * * No measuring, appraising or auditing of newly created tmpfiles is needed. * Skip calling process_measurement(), but indicate which newly, created * tmpfiles are in policy. */ -void ima_post_create_tmpfile(struct inode *inode) +void ima_post_create_tmpfile(struct user_namespace *mnt_userns, + struct inode *inode) { struct integrity_iint_cache *iint; int must_appraise; - must_appraise = ima_must_appraise(inode, MAY_ACCESS, FILE_CHECK); + if (!ima_policy_flag || !S_ISREG(inode->i_mode)) + return; + + must_appraise = ima_must_appraise(mnt_userns, inode, MAY_ACCESS, + FILE_CHECK); if (!must_appraise) return; @@ -474,18 +643,24 @@ void ima_post_create_tmpfile(struct inode *inode) /** * ima_post_path_mknod - mark as a new inode + * @mnt_userns: user namespace of the mount the inode was found from * @dentry: newly created dentry * * Mark files created via the mknodat syscall as new, so that the * file data can be written later. */ -void ima_post_path_mknod(struct dentry *dentry) +void ima_post_path_mknod(struct user_namespace *mnt_userns, + struct dentry *dentry) { struct integrity_iint_cache *iint; struct inode *inode = dentry->d_inode; int must_appraise; - must_appraise = ima_must_appraise(inode, MAY_ACCESS, FILE_CHECK); + if (!ima_policy_flag || !S_ISREG(inode->i_mode)) + return; + + must_appraise = ima_must_appraise(mnt_userns, inode, MAY_ACCESS, + FILE_CHECK); if (!must_appraise) return; @@ -502,6 +677,7 @@ void ima_post_path_mknod(struct dentry *dentry) * ima_read_file - pre-measure/appraise hook decision based on policy * @file: pointer to the file to be measured/appraised/audit * @read_id: caller identifier + * @contents: whether a subsequent call will be made to ima_post_read_file() * * Permit reading a file based on policy. The policy rules are written * in terms of the policy identifier. Appraising the integrity of @@ -509,22 +685,37 @@ void ima_post_path_mknod(struct dentry *dentry) * * For permission return 0, otherwise return -EACCES. */ -int ima_read_file(struct file *file, enum kernel_read_file_id read_id) +int ima_read_file(struct file *file, enum kernel_read_file_id read_id, + bool contents) { + enum ima_hooks func; + u32 secid; + /* - * READING_FIRMWARE_PREALLOC_BUFFER - * * Do devices using pre-allocated memory run the risk of the * firmware being accessible to the device prior to the completion * of IMA's signature verification any more than when using two - * buffers? + * buffers? It may be desirable to include the buffer address + * in this API and walk all the dma_map_single() mappings to check. */ - return 0; + + /* + * There will be a call made to ima_post_read_file() with + * a filled buffer, so we don't need to perform an extra + * read early here. + */ + if (contents) + return 0; + + /* Read entire file for all partial reads. */ + func = read_idmap[read_id] ?: FILE_CHECK; + security_task_getsecid_subj(current, &secid); + return process_measurement(file, current_cred(), secid, NULL, + 0, MAY_READ, func); } const int read_idmap[READING_MAX_ID] = { [READING_FIRMWARE] = FIRMWARE_CHECK, - [READING_FIRMWARE_PREALLOC_BUFFER] = FIRMWARE_CHECK, [READING_MODULE] = MODULE_CHECK, [READING_KEXEC_IMAGE] = KEXEC_KERNEL_CHECK, [READING_KEXEC_INITRAMFS] = KEXEC_INITRAMFS_CHECK, @@ -550,15 +741,6 @@ int ima_post_read_file(struct file *file, void *buf, loff_t size, enum ima_hooks func; u32 secid; - if (!file && read_id == READING_FIRMWARE) { - if ((ima_appraise & IMA_APPRAISE_FIRMWARE) && - (ima_appraise & IMA_APPRAISE_ENFORCE)) { - pr_err("Prevent firmware loading_store.\n"); - return -EACCES; /* INTEGRITY_UNKNOWN */ - } - return 0; - } - /* permit signed certs */ if (!file && read_id == READING_X509_CERTIFICATE) return 0; @@ -570,7 +752,7 @@ int ima_post_read_file(struct file *file, void *buf, loff_t size, } func = read_idmap[read_id] ?: FILE_CHECK; - security_task_getsecid(current, &secid); + security_task_getsecid_subj(current, &secid); return process_measurement(file, current_cred(), secid, buf, size, MAY_READ, func); } @@ -578,6 +760,8 @@ int ima_post_read_file(struct file *file, void *buf, loff_t size, /** * ima_load_data - appraise decision based on policy * @id: kernel load data caller identifier + * @contents: whether the full contents will be available in a later + * call to ima_post_load_data(). * * Callers of this LSM hook can not measure, appraise, or audit the * data provided by userspace. Enforce policy rules requring a file @@ -585,7 +769,7 @@ int ima_post_read_file(struct file *file, void *buf, loff_t size, * * For permission return 0, otherwise return -EACCES. */ -int ima_load_data(enum kernel_load_data_id id) +int ima_load_data(enum kernel_load_data_id id, bool contents) { bool ima_enforce, sig_enforce; @@ -606,7 +790,7 @@ int ima_load_data(enum kernel_load_data_id id) } break; case LOADING_FIRMWARE: - if (ima_enforce && (ima_appraise & IMA_APPRAISE_FIRMWARE)) { + if (ima_enforce && (ima_appraise & IMA_APPRAISE_FIRMWARE) && !contents) { pr_err("Prevent firmware sysfs fallback loading.\n"); return -EACCES; /* INTEGRITY_UNKNOWN */ } @@ -619,42 +803,100 @@ int ima_load_data(enum kernel_load_data_id id) pr_err("impossible to appraise a module without a file descriptor. sig_enforce kernel parameter might help\n"); return -EACCES; /* INTEGRITY_UNKNOWN */ } + break; default: break; } return 0; } -/* - * process_buffer_measurement - Measure the buffer to ima log. +/** + * ima_post_load_data - appraise decision based on policy + * @buf: pointer to in memory file contents + * @size: size of in memory file contents + * @id: kernel load data caller identifier + * @description: @id-specific description of contents + * + * Measure/appraise/audit in memory buffer based on policy. Policy rules + * are written in terms of a policy identifier. + * + * On success return 0. On integrity appraisal error, assuming the file + * is in policy and IMA-appraisal is in enforcing mode, return -EACCES. + */ +int ima_post_load_data(char *buf, loff_t size, + enum kernel_load_data_id load_id, + char *description) +{ + if (load_id == LOADING_FIRMWARE) { + if ((ima_appraise & IMA_APPRAISE_FIRMWARE) && + (ima_appraise & IMA_APPRAISE_ENFORCE)) { + pr_err("Prevent firmware loading_store.\n"); + return -EACCES; /* INTEGRITY_UNKNOWN */ + } + return 0; + } + + return 0; +} + +/** + * process_buffer_measurement - Measure the buffer or the buffer data hash + * @mnt_userns: user namespace of the mount the inode was found from + * @inode: inode associated with the object being measured (NULL for KEY_CHECK) * @buf: pointer to the buffer that needs to be added to the log. * @size: size of buffer(in bytes). * @eventname: event name to be used for the buffer entry. * @func: IMA hook * @pcr: pcr to extend the measurement + * @func_data: func specific data, may be NULL + * @buf_hash: measure buffer data hash + * @digest: buffer digest will be written to + * @digest_len: buffer length + * + * Based on policy, either the buffer data or buffer data hash is measured * - * Based on policy, the buffer is measured into the ima log. + * Return: 0 if the buffer has been successfully measured, 1 if the digest + * has been written to the passed location but not added to a measurement entry, + * a negative value otherwise. */ -void process_buffer_measurement(const void *buf, int size, - const char *eventname, enum ima_hooks func, - int pcr) +int process_buffer_measurement(struct user_namespace *mnt_userns, + struct inode *inode, const void *buf, int size, + const char *eventname, enum ima_hooks func, + int pcr, const char *func_data, + bool buf_hash, u8 *digest, size_t digest_len) { int ret = 0; + const char *audit_cause = "ENOMEM"; struct ima_template_entry *entry = NULL; struct integrity_iint_cache iint = {}; struct ima_event_data event_data = {.iint = &iint, .filename = eventname, .buf = buf, .buf_len = size}; - struct ima_template_desc *template = NULL; + struct ima_template_desc *template; struct { struct ima_digest_data hdr; char digest[IMA_MAX_DIGEST_SIZE]; } hash = {}; + char digest_hash[IMA_MAX_DIGEST_SIZE]; + int digest_hash_len = hash_digest_size[ima_hash_algo]; int violation = 0; int action = 0; u32 secid; + if (digest && digest_len < digest_hash_len) + return -EINVAL; + + if (!ima_policy_flag && !digest) + return -ENOENT; + + template = ima_template_desc_buf(); + if (!template) { + ret = -EINVAL; + audit_cause = "ima_template_desc_buf"; + goto out; + } + /* * Both LSM hooks and auxilary based buffer measurements are * based on policy. To avoid code duplication, differentiate @@ -663,68 +905,132 @@ void process_buffer_measurement(const void *buf, int size, * buffer measurements. */ if (func) { - security_task_getsecid(current, &secid); - action = ima_get_action(NULL, current_cred(), secid, 0, func, - &pcr, &template); - if (!(action & IMA_MEASURE)) - return; + security_task_getsecid_subj(current, &secid); + action = ima_get_action(mnt_userns, inode, current_cred(), + secid, 0, func, &pcr, &template, + func_data, NULL); + if (!(action & IMA_MEASURE) && !digest) + return -ENOENT; } if (!pcr) pcr = CONFIG_IMA_MEASURE_PCR_IDX; - if (!template) { - template = lookup_template_desc("ima-buf"); - ret = template_desc_init_fields(template->fmt, - &(template->fields), - &(template->num_fields)); - if (ret < 0) { - pr_err("template %s init failed, result: %d\n", - (strlen(template->name) ? - template->name : template->fmt), ret); - return; - } - } - iint.ima_hash = &hash.hdr; iint.ima_hash->algo = ima_hash_algo; iint.ima_hash->length = hash_digest_size[ima_hash_algo]; ret = ima_calc_buffer_hash(buf, size, iint.ima_hash); - if (ret < 0) + if (ret < 0) { + audit_cause = "hashing_error"; goto out; + } + + if (buf_hash) { + memcpy(digest_hash, hash.hdr.digest, digest_hash_len); + + ret = ima_calc_buffer_hash(digest_hash, digest_hash_len, + iint.ima_hash); + if (ret < 0) { + audit_cause = "hashing_error"; + goto out; + } + + event_data.buf = digest_hash; + event_data.buf_len = digest_hash_len; + } + + if (digest) + memcpy(digest, iint.ima_hash->digest, digest_hash_len); + + if (!ima_policy_flag || (func && !(action & IMA_MEASURE))) + return 1; ret = ima_alloc_init_template(&event_data, &entry, template); - if (ret < 0) + if (ret < 0) { + audit_cause = "alloc_entry"; goto out; + } - ret = ima_store_template(entry, violation, NULL, buf, pcr); - - if (ret < 0) + ret = ima_store_template(entry, violation, NULL, event_data.buf, pcr); + if (ret < 0) { + audit_cause = "store_entry"; ima_free_template_entry(entry); + } out: - return; + if (ret < 0) + integrity_audit_message(AUDIT_INTEGRITY_PCR, NULL, eventname, + func_measure_str(func), + audit_cause, ret, 0, ret); + + return ret; } /** * ima_kexec_cmdline - measure kexec cmdline boot args + * @kernel_fd: file descriptor of the kexec kernel being loaded * @buf: pointer to buffer * @size: size of buffer * * Buffers can only be measured, not appraised. */ -void ima_kexec_cmdline(const void *buf, int size) +void ima_kexec_cmdline(int kernel_fd, const void *buf, int size) +{ + struct fd f; + + if (!buf || !size) + return; + + f = fdget(kernel_fd); + if (!f.file) + return; + + process_buffer_measurement(file_mnt_user_ns(f.file), file_inode(f.file), + buf, size, "kexec-cmdline", KEXEC_CMDLINE, 0, + NULL, false, NULL, 0); + fdput(f); +} + +/** + * ima_measure_critical_data - measure kernel integrity critical data + * @event_label: unique event label for grouping and limiting critical data + * @event_name: event name for the record in the IMA measurement list + * @buf: pointer to buffer data + * @buf_len: length of buffer data (in bytes) + * @hash: measure buffer data hash + * @digest: buffer digest will be written to + * @digest_len: buffer length + * + * Measure data critical to the integrity of the kernel into the IMA log + * and extend the pcr. Examples of critical data could be various data + * structures, policies, and states stored in kernel memory that can + * impact the integrity of the system. + * + * Return: 0 if the buffer has been successfully measured, 1 if the digest + * has been written to the passed location but not added to a measurement entry, + * a negative value otherwise. + */ +int ima_measure_critical_data(const char *event_label, + const char *event_name, + const void *buf, size_t buf_len, + bool hash, u8 *digest, size_t digest_len) { - if (buf && size != 0) - process_buffer_measurement(buf, size, "kexec-cmdline", - KEXEC_CMDLINE, 0); + if (!event_name || !event_label || !buf || !buf_len) + return -ENOPARAM; + + return process_buffer_measurement(&init_user_ns, NULL, buf, buf_len, + event_name, CRITICAL_DATA, 0, + event_label, hash, digest, + digest_len); } +EXPORT_SYMBOL_GPL(ima_measure_critical_data); static int __init init_ima(void) { int error; + ima_appraise_parse_cmdline(); ima_init_template_list(); hash_setup(CONFIG_IMA_DEFAULT_HASH); error = ima_init(); @@ -738,12 +1044,15 @@ static int __init init_ima(void) error = ima_init(); } + if (error) + return error; + error = register_blocking_lsm_notifier(&ima_lsm_policy_notifier); if (error) pr_warn("Couldn't register LSM notifier, error %d\n", error); if (!error) - ima_update_policy_flag(); + ima_update_policy_flags(); return error; } |