diff options
| -rw-r--r-- | Documentation/ABI/testing/ima_policy | 15 | ||||
| -rw-r--r-- | drivers/md/dm-ima.c | 3 | ||||
| -rw-r--r-- | include/linux/ima.h | 23 | ||||
| -rw-r--r-- | security/integrity/ima/Kconfig | 1 | ||||
| -rw-r--r-- | security/integrity/ima/ima.h | 24 | ||||
| -rw-r--r-- | security/integrity/ima/ima_api.c | 6 | ||||
| -rw-r--r-- | security/integrity/ima/ima_appraise.c | 78 | ||||
| -rw-r--r-- | security/integrity/ima/ima_asymmetric_keys.c | 2 | ||||
| -rw-r--r-- | security/integrity/ima/ima_init.c | 3 | ||||
| -rw-r--r-- | security/integrity/ima/ima_main.c | 89 | ||||
| -rw-r--r-- | security/integrity/ima/ima_mok.c | 2 | ||||
| -rw-r--r-- | security/integrity/ima/ima_policy.c | 174 | ||||
| -rw-r--r-- | security/integrity/ima/ima_queue_keys.c | 2 | ||||
| -rw-r--r-- | security/selinux/ima.c | 6 |
14 files changed, 352 insertions, 76 deletions
diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy index 070779e8d836..5c2798534950 100644 --- a/Documentation/ABI/testing/ima_policy +++ b/Documentation/ABI/testing/ima_policy @@ -27,12 +27,13 @@ Description: lsm: [[subj_user=] [subj_role=] [subj_type=] [obj_user=] [obj_role=] [obj_type=]] option: [[appraise_type=]] [template=] [permit_directio] - [appraise_flag=] [keyrings=] + [appraise_flag=] [appraise_algos=] [keyrings=] base: func:= [BPRM_CHECK][MMAP_CHECK][CREDS_CHECK][FILE_CHECK][MODULE_CHECK] - [FIRMWARE_CHECK] + [FIRMWARE_CHECK] [KEXEC_KERNEL_CHECK] [KEXEC_INITRAMFS_CHECK] [KEXEC_CMDLINE] [KEY_CHECK] [CRITICAL_DATA] + [SETXATTR_CHECK] mask:= [[^]MAY_READ] [[^]MAY_WRITE] [[^]MAY_APPEND] [[^]MAY_EXEC] fsmagic:= hex value @@ -55,6 +56,10 @@ Description: label:= [selinux]|[kernel_info]|[data_label] data_label:= a unique string used for grouping and limiting critical data. For example, "selinux" to measure critical data for SELinux. + appraise_algos:= comma-separated list of hash algorithms + For example, "sha256,sha512" to only accept to appraise + files where the security.ima xattr was hashed with one + of these two algorithms. default policy: # PROC_SUPER_MAGIC @@ -134,3 +139,9 @@ Description: keys added to .builtin_trusted_keys or .ima keyring: measure func=KEY_CHECK keyrings=.builtin_trusted_keys|.ima + + Example of the special SETXATTR_CHECK appraise rule, that + restricts the hash algorithms allowed when writing to the + security.ima xattr of a file: + + appraise func=SETXATTR_CHECK appraise_algos=sha256,sha384,sha512 diff --git a/drivers/md/dm-ima.c b/drivers/md/dm-ima.c index 3fd69ab12a8e..2c5edfbd7711 100644 --- a/drivers/md/dm-ima.c +++ b/drivers/md/dm-ima.c @@ -136,7 +136,8 @@ static void dm_ima_measure_data(const char *event_name, const void *buf, size_t if (noio) noio_flag = memalloc_noio_save(); - ima_measure_critical_data(DM_NAME, event_name, buf, buf_len, false); + ima_measure_critical_data(DM_NAME, event_name, buf, buf_len, + false, NULL, 0); if (noio) memalloc_noio_restore(noio_flag); diff --git a/include/linux/ima.h b/include/linux/ima.h index 61d5723ec303..b6ab66a546ae 100644 --- a/include/linux/ima.h +++ b/include/linux/ima.h @@ -11,9 +11,11 @@ #include <linux/fs.h> #include <linux/security.h> #include <linux/kexec.h> +#include <crypto/hash_info.h> struct linux_binprm; #ifdef CONFIG_IMA +extern enum hash_algo ima_get_current_hash_algo(void); extern int ima_bprm_check(struct linux_binprm *bprm); extern int ima_file_check(struct file *file, int mask); extern void ima_post_create_tmpfile(struct user_namespace *mnt_userns, @@ -33,10 +35,10 @@ extern void ima_post_path_mknod(struct user_namespace *mnt_userns, extern int ima_file_hash(struct file *file, char *buf, size_t buf_size); extern int ima_inode_hash(struct inode *inode, char *buf, size_t buf_size); extern void ima_kexec_cmdline(int kernel_fd, const void *buf, int size); -extern void ima_measure_critical_data(const char *event_label, - const char *event_name, - const void *buf, size_t buf_len, - bool hash); +extern 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); #ifdef CONFIG_IMA_APPRAISE_BOOTPARAM extern void ima_appraise_parse_cmdline(void); @@ -64,6 +66,11 @@ static inline const char * const *arch_get_ima_policy(void) #endif #else +static inline enum hash_algo ima_get_current_hash_algo(void) +{ + return HASH_ALGO__LAST; +} + static inline int ima_bprm_check(struct linux_binprm *bprm) { return 0; @@ -137,10 +144,14 @@ static inline int ima_inode_hash(struct inode *inode, char *buf, size_t buf_size static inline void ima_kexec_cmdline(int kernel_fd, const void *buf, int size) {} -static inline void ima_measure_critical_data(const char *event_label, +static inline int ima_measure_critical_data(const char *event_label, const char *event_name, const void *buf, size_t buf_len, - bool hash) {} + bool hash, u8 *digest, + size_t digest_len) +{ + return -ENOENT; +} #endif /* CONFIG_IMA */ diff --git a/security/integrity/ima/Kconfig b/security/integrity/ima/Kconfig index d0ceada99243..f3a9cc201c8c 100644 --- a/security/integrity/ima/Kconfig +++ b/security/integrity/ima/Kconfig @@ -6,7 +6,6 @@ config IMA select SECURITYFS select CRYPTO select CRYPTO_HMAC - select CRYPTO_MD5 select CRYPTO_SHA1 select CRYPTO_HASH_INFO select TCG_TPM if HAS_IOMEM && !UML diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index f0e448ed1f9f..be965a8715e4 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -46,8 +46,11 @@ enum tpm_pcrs { TPM_PCR0 = 0, TPM_PCR8 = 8, TPM_PCR10 = 10 }; /* current content of the policy */ extern int ima_policy_flag; +/* bitset of digests algorithms allowed in the setxattr hook */ +extern atomic_t ima_setxattr_allowed_hash_algorithms; + /* set during initialization */ -extern int ima_hash_algo; +extern int ima_hash_algo __ro_after_init; extern int ima_sha1_idx __ro_after_init; extern int ima_hash_algo_idx __ro_after_init; extern int ima_extra_slots __ro_after_init; @@ -198,6 +201,7 @@ static inline unsigned int ima_hash_key(u8 *digest) hook(KEXEC_CMDLINE, kexec_cmdline) \ hook(KEY_CHECK, key) \ hook(CRITICAL_DATA, critical_data) \ + hook(SETXATTR_CHECK, setxattr_check) \ hook(MAX_CHECK, none) #define __ima_hook_enumify(ENUM, str) ENUM, @@ -254,7 +258,7 @@ int ima_get_action(struct user_namespace *mnt_userns, struct inode *inode, const struct cred *cred, u32 secid, int mask, enum ima_hooks func, int *pcr, struct ima_template_desc **template_desc, - const char *func_data); + const char *func_data, unsigned int *allowed_algos); int ima_must_measure(struct inode *inode, int mask, enum ima_hooks func); int ima_collect_measurement(struct integrity_iint_cache *iint, struct file *file, void *buf, loff_t size, @@ -264,11 +268,11 @@ void ima_store_measurement(struct integrity_iint_cache *iint, struct file *file, struct evm_ima_xattr_data *xattr_value, int xattr_len, const struct modsig *modsig, int pcr, struct ima_template_desc *template_desc); -void 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); +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); void ima_audit_measurement(struct integrity_iint_cache *iint, const unsigned char *filename); int ima_alloc_init_template(struct ima_event_data *event_data, @@ -285,10 +289,10 @@ int ima_match_policy(struct user_namespace *mnt_userns, struct inode *inode, const struct cred *cred, u32 secid, enum ima_hooks func, int mask, int flags, int *pcr, struct ima_template_desc **template_desc, - const char *func_data); + const char *func_data, unsigned int *allowed_algos); void ima_init_policy(void); void ima_update_policy(void); -void ima_update_policy_flag(void); +void ima_update_policy_flags(void); ssize_t ima_parse_add_rule(char *); void ima_delete_rules(void); int ima_check_policy(void); @@ -319,7 +323,7 @@ int ima_must_appraise(struct user_namespace *mnt_userns, struct inode *inode, void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file); enum integrity_status ima_get_cache_status(struct integrity_iint_cache *iint, enum ima_hooks func); -enum hash_algo ima_get_hash_algo(struct evm_ima_xattr_data *xattr_value, +enum hash_algo ima_get_hash_algo(const struct evm_ima_xattr_data *xattr_value, int xattr_len); int ima_read_xattr(struct dentry *dentry, struct evm_ima_xattr_data **xattr_value); diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c index d8e321cc6936..2c6c3a5228b5 100644 --- a/security/integrity/ima/ima_api.c +++ b/security/integrity/ima/ima_api.c @@ -172,6 +172,7 @@ err_out: * @pcr: pointer filled in if matched measure policy sets pcr= * @template_desc: pointer filled in if matched measure policy sets template= * @func_data: func specific data, may be NULL + * @allowed_algos: allowlist of hash algorithms for the IMA xattr * * The policy is defined in terms of keypairs: * subj=, obj=, type=, func=, mask=, fsmagic= @@ -188,14 +189,15 @@ int ima_get_action(struct user_namespace *mnt_userns, struct inode *inode, const struct cred *cred, u32 secid, int mask, enum ima_hooks func, int *pcr, struct ima_template_desc **template_desc, - const char *func_data) + const char *func_data, unsigned int *allowed_algos) { int flags = IMA_MEASURE | IMA_AUDIT | IMA_APPRAISE | IMA_HASH; flags &= ima_policy_flag; return ima_match_policy(mnt_userns, inode, cred, secid, func, mask, - flags, pcr, template_desc, func_data); + flags, pcr, template_desc, func_data, + allowed_algos); } /* diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c index ef9dcfce45d4..dbba51583e7c 100644 --- a/security/integrity/ima/ima_appraise.c +++ b/security/integrity/ima/ima_appraise.c @@ -77,8 +77,9 @@ int ima_must_appraise(struct user_namespace *mnt_userns, struct inode *inode, return 0; security_task_getsecid_subj(current, &secid); - return ima_match_policy(mnt_userns, inode, current_cred(), secid, func, - mask, IMA_APPRAISE | IMA_HASH, NULL, NULL, NULL); + return ima_match_policy(mnt_userns, inode, current_cred(), secid, + func, mask, IMA_APPRAISE | IMA_HASH, NULL, + NULL, NULL, NULL); } static int ima_fix_xattr(struct dentry *dentry, @@ -171,7 +172,7 @@ static void ima_cache_flags(struct integrity_iint_cache *iint, } } -enum hash_algo ima_get_hash_algo(struct evm_ima_xattr_data *xattr_value, +enum hash_algo ima_get_hash_algo(const struct evm_ima_xattr_data *xattr_value, int xattr_len) { struct signature_v2_hdr *sig; @@ -184,7 +185,8 @@ enum hash_algo ima_get_hash_algo(struct evm_ima_xattr_data *xattr_value, switch (xattr_value->type) { case EVM_IMA_XATTR_DIGSIG: sig = (typeof(sig))xattr_value; - if (sig->version != 2 || xattr_len <= sizeof(*sig)) + if (sig->version != 2 || xattr_len <= sizeof(*sig) + || sig->hash_algo >= HASH_ALGO__LAST) return ima_hash_algo; return sig->hash_algo; break; @@ -357,7 +359,7 @@ int ima_check_blacklist(struct integrity_iint_cache *iint, if ((rc == -EPERM) && (iint->flags & IMA_MEASURE)) process_buffer_measurement(&init_user_ns, NULL, digest, digestsize, "blacklisted-hash", NONE, - pcr, NULL, false); + pcr, NULL, false, NULL, 0); } return rc; @@ -575,6 +577,66 @@ static void ima_reset_appraise_flags(struct inode *inode, int digsig) 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) { @@ -592,9 +654,11 @@ int ima_inode_setxattr(struct dentry *dentry, const char *xattr_name, digsig = (xvalue->type == EVM_XATTR_PORTABLE_DIGSIG); } 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; } diff --git a/security/integrity/ima/ima_asymmetric_keys.c b/security/integrity/ima/ima_asymmetric_keys.c index c985418698a4..f6aa0b47a772 100644 --- a/security/integrity/ima/ima_asymmetric_keys.c +++ b/security/integrity/ima/ima_asymmetric_keys.c @@ -62,5 +62,5 @@ void ima_post_key_create_or_update(struct key *keyring, struct key *key, */ process_buffer_measurement(&init_user_ns, NULL, payload, payload_len, keyring->description, KEY_CHECK, 0, - keyring->description, false); + keyring->description, false, NULL, 0); } diff --git a/security/integrity/ima/ima_init.c b/security/integrity/ima/ima_init.c index 5076a7d9d23e..b26fa67476b4 100644 --- a/security/integrity/ima/ima_init.c +++ b/security/integrity/ima/ima_init.c @@ -154,7 +154,8 @@ int __init ima_init(void) ima_init_key_queue(); ima_measure_critical_data("kernel_info", "kernel_version", - UTS_RELEASE, strlen(UTS_RELEASE), false); + UTS_RELEASE, strlen(UTS_RELEASE), false, + NULL, 0); return rc; } diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index 673833f94069..465865412100 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -35,7 +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 = { @@ -76,6 +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, @@ -210,6 +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; @@ -219,7 +225,8 @@ static int process_measurement(struct file *file, const struct cred *cred, * Included is the appraise submask. */ action = ima_get_action(file_mnt_user_ns(file), inode, cred, secid, - mask, func, &pcr, &template_desc, NULL); + 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) @@ -356,6 +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)) @@ -433,7 +450,7 @@ int ima_file_mprotect(struct vm_area_struct *vma, unsigned long prot) 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); + &pcr, &template, NULL, NULL); /* Is the mmap'ed file in policy? */ if (!(action & (IMA_MEASURE | IMA_APPRAISE_SUBMASK))) @@ -822,7 +839,7 @@ int ima_post_load_data(char *buf, loff_t size, 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) @@ -833,14 +850,20 @@ int ima_post_load_data(char *buf, loff_t size, * @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 + * + * 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(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) +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"; @@ -861,8 +884,11 @@ void process_buffer_measurement(struct user_namespace *mnt_userns, int action = 0; u32 secid; - if (!ima_policy_flag) - return; + if (digest && digest_len < digest_hash_len) + return -EINVAL; + + if (!ima_policy_flag && !digest) + return -ENOENT; template = ima_template_desc_buf(); if (!template) { @@ -882,9 +908,9 @@ void process_buffer_measurement(struct user_namespace *mnt_userns, security_task_getsecid_subj(current, &secid); action = ima_get_action(mnt_userns, inode, current_cred(), secid, 0, func, &pcr, &template, - func_data); - if (!(action & IMA_MEASURE)) - return; + func_data, NULL); + if (!(action & IMA_MEASURE) && !digest) + return -ENOENT; } if (!pcr) @@ -914,6 +940,12 @@ void process_buffer_measurement(struct user_namespace *mnt_userns, 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) { audit_cause = "alloc_entry"; @@ -932,7 +964,7 @@ out: func_measure_str(func), audit_cause, ret, 0, ret); - return; + return ret; } /** @@ -956,7 +988,7 @@ void ima_kexec_cmdline(int kernel_fd, const void *buf, int size) process_buffer_measurement(file_mnt_user_ns(f.file), file_inode(f.file), buf, size, "kexec-cmdline", KEXEC_CMDLINE, 0, - NULL, false); + NULL, false, NULL, 0); fdput(f); } @@ -967,23 +999,30 @@ void ima_kexec_cmdline(int kernel_fd, const void *buf, int size) * @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. */ -void ima_measure_critical_data(const char *event_label, - const char *event_name, - const void *buf, size_t buf_len, - bool hash) +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 (!event_name || !event_label || !buf || !buf_len) - return; + return -ENOPARAM; - process_buffer_measurement(&init_user_ns, NULL, buf, buf_len, event_name, - CRITICAL_DATA, 0, event_label, - hash); + 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); @@ -1013,7 +1052,7 @@ static int __init init_ima(void) pr_warn("Couldn't register LSM notifier, error %d\n", error); if (!error) - ima_update_policy_flag(); + ima_update_policy_flags(); return error; } diff --git a/security/integrity/ima/ima_mok.c b/security/integrity/ima/ima_mok.c index 1e5c01916173..95cc31525c57 100644 --- a/security/integrity/ima/ima_mok.c +++ b/security/integrity/ima/ima_mok.c @@ -21,7 +21,7 @@ struct key *ima_blacklist_keyring; /* * Allocate the IMA blacklist keyring */ -__init int ima_mok_init(void) +static __init int ima_mok_init(void) { struct key_restriction *restriction; diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c index fd5d46e511f1..87b9b71cb820 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -35,6 +35,7 @@ #define IMA_FSNAME 0x0200 #define IMA_KEYRINGS 0x0400 #define IMA_LABEL 0x0800 +#define IMA_VALIDATE_ALGOS 0x1000 #define UNKNOWN 0 #define MEASURE 0x0001 /* same as IMA_MEASURE */ @@ -52,6 +53,8 @@ int ima_policy_flag; static int temp_ima_appraise; static int build_ima_appraise __ro_after_init; +atomic_t ima_setxattr_allowed_hash_algorithms; + #define MAX_LSM_RULES 6 enum lsm_rule_types { LSM_OBJ_USER, LSM_OBJ_ROLE, LSM_OBJ_TYPE, LSM_SUBJ_USER, LSM_SUBJ_ROLE, LSM_SUBJ_TYPE @@ -79,6 +82,7 @@ struct ima_rule_entry { bool (*uid_op)(kuid_t, kuid_t); /* Handlers for operators */ bool (*fowner_op)(kuid_t, kuid_t); /* uid_eq(), uid_gt(), uid_lt() */ int pcr; + unsigned int allowed_algos; /* bitfield of allowed hash algorithms */ struct { void *rule; /* LSM file metadata specific */ char *args_p; /* audit value */ @@ -91,6 +95,14 @@ struct ima_rule_entry { }; /* + * sanity check in case the kernels gains more hash algorithms that can + * fit in an unsigned int + */ +static_assert( + 8 * sizeof(unsigned int) >= HASH_ALGO__LAST, + "The bitfield allowed_algos in ima_rule_entry is too small to contain all the supported hash algorithms, consider using a bigger type"); + +/* * Without LSM specific knowledge, the default policy can only be * written in terms of .action, .func, .mask, .fsmagic, .uid, and .fowner */ @@ -646,6 +658,7 @@ static int get_subaction(struct ima_rule_entry *rule, enum ima_hooks func) * @pcr: set the pcr to extend * @template_desc: the template that should be used for this rule * @func_data: func specific data, may be NULL + * @allowed_algos: allowlist of hash algorithms for the IMA xattr * * Measure decision based on func/mask/fsmagic and LSM(subj/obj/type) * conditions. @@ -658,7 +671,7 @@ int ima_match_policy(struct user_namespace *mnt_userns, struct inode *inode, const struct cred *cred, u32 secid, enum ima_hooks func, int mask, int flags, int *pcr, struct ima_template_desc **template_desc, - const char *func_data) + const char *func_data, unsigned int *allowed_algos) { struct ima_rule_entry *entry; int action = 0, actmask = flags | (flags << 1); @@ -684,8 +697,11 @@ int ima_match_policy(struct user_namespace *mnt_userns, struct inode *inode, action &= ~IMA_HASH; if (ima_fail_unverifiable_sigs) action |= IMA_FAIL_UNVERIFIABLE_SIGS; - } + if (allowed_algos && + entry->flags & IMA_VALIDATE_ALGOS) + *allowed_algos = entry->allowed_algos; + } if (entry->action & IMA_DO_MASK) actmask &= ~(entry->action | entry->action << 1); @@ -706,24 +722,57 @@ int ima_match_policy(struct user_namespace *mnt_userns, struct inode *inode, return action; } -/* - * Initialize the ima_policy_flag variable based on the currently - * loaded policy. Based on this flag, the decision to short circuit - * out of a function or not call the function in the first place - * can be made earlier. +/** + * ima_update_policy_flags() - Update global IMA variables + * + * Update ima_policy_flag and ima_setxattr_allowed_hash_algorithms + * based on the currently loaded policy. + * + * With ima_policy_flag, the decision to short circuit out of a function + * or not call the function in the first place can be made earlier. + * + * With ima_setxattr_allowed_hash_algorithms, the policy can restrict the + * set of hash algorithms accepted when updating the security.ima xattr of + * a file. + * + * Context: called after a policy update and at system initialization. */ -void ima_update_policy_flag(void) +void ima_update_policy_flags(void) { struct ima_rule_entry *entry; + int new_policy_flag = 0; + rcu_read_lock(); list_for_each_entry(entry, ima_rules, list) { + /* + * SETXATTR_CHECK rules do not implement a full policy check + * because rule checking would probably have an important + * performance impact on setxattr(). As a consequence, only one + * SETXATTR_CHECK can be active at a given time. + * Because we want to preserve that property, we set out to use + * atomic_cmpxchg. Either: + * - the atomic was non-zero: a setxattr hash policy is + * already enforced, we do nothing + * - the atomic was zero: no setxattr policy was set, enable + * the setxattr hash policy + */ + if (entry->func == SETXATTR_CHECK) { + atomic_cmpxchg(&ima_setxattr_allowed_hash_algorithms, + 0, entry->allowed_algos); + /* SETXATTR_CHECK doesn't impact ima_policy_flag */ + continue; + } + if (entry->action & IMA_DO_MASK) - ima_policy_flag |= entry->action; + new_policy_flag |= entry->action; } + rcu_read_unlock(); ima_appraise |= (build_ima_appraise | temp_ima_appraise); if (!ima_appraise) - ima_policy_flag &= ~IMA_APPRAISE; + new_policy_flag &= ~IMA_APPRAISE; + + ima_policy_flag = new_policy_flag; } static int ima_appraise_flag(enum ima_hooks func) @@ -889,7 +938,9 @@ void __init ima_init_policy(void) ARRAY_SIZE(critical_data_rules), IMA_DEFAULT_POLICY); - ima_update_policy_flag(); + atomic_set(&ima_setxattr_allowed_hash_algorithms, 0); + + ima_update_policy_flags(); } /* Make sure we have a valid policy, at least containing some rules. */ @@ -929,7 +980,7 @@ void ima_update_policy(void) */ kfree(arch_policy_entry); } - ima_update_policy_flag(); + ima_update_policy_flags(); /* Custom IMA policy has been loaded */ ima_process_queued_keys(); @@ -946,7 +997,7 @@ enum { Opt_fsuuid, Opt_uid_eq, Opt_euid_eq, Opt_fowner_eq, Opt_uid_gt, Opt_euid_gt, Opt_fowner_gt, Opt_uid_lt, Opt_euid_lt, Opt_fowner_lt, - Opt_appraise_type, Opt_appraise_flag, + Opt_appraise_type, Opt_appraise_flag, Opt_appraise_algos, Opt_permit_directio, Opt_pcr, Opt_template, Opt_keyrings, Opt_label, Opt_err }; @@ -981,6 +1032,7 @@ static const match_table_t policy_tokens = { {Opt_fowner_lt, "fowner<%s"}, {Opt_appraise_type, "appraise_type=%s"}, {Opt_appraise_flag, "appraise_flag=%s"}, + {Opt_appraise_algos, "appraise_algos=%s"}, {Opt_permit_directio, "permit_directio"}, {Opt_pcr, "pcr=%s"}, {Opt_template, "template=%s"}, @@ -1081,7 +1133,8 @@ static bool ima_validate_rule(struct ima_rule_entry *entry) return false; if (entry->action != APPRAISE && - entry->flags & (IMA_DIGSIG_REQUIRED | IMA_MODSIG_ALLOWED | IMA_CHECK_BLACKLIST)) + entry->flags & (IMA_DIGSIG_REQUIRED | IMA_MODSIG_ALLOWED | + IMA_CHECK_BLACKLIST | IMA_VALIDATE_ALGOS)) return false; /* @@ -1111,7 +1164,7 @@ static bool ima_validate_rule(struct ima_rule_entry *entry) IMA_UID | IMA_FOWNER | IMA_FSUUID | IMA_INMASK | IMA_EUID | IMA_PCR | IMA_FSNAME | IMA_DIGSIG_REQUIRED | - IMA_PERMIT_DIRECTIO)) + IMA_PERMIT_DIRECTIO | IMA_VALIDATE_ALGOS)) return false; break; @@ -1123,7 +1176,7 @@ static bool ima_validate_rule(struct ima_rule_entry *entry) IMA_INMASK | IMA_EUID | IMA_PCR | IMA_FSNAME | IMA_DIGSIG_REQUIRED | IMA_PERMIT_DIRECTIO | IMA_MODSIG_ALLOWED | - IMA_CHECK_BLACKLIST)) + IMA_CHECK_BLACKLIST | IMA_VALIDATE_ALGOS)) return false; break; @@ -1161,6 +1214,23 @@ static bool ima_validate_rule(struct ima_rule_entry *entry) return false; break; + case SETXATTR_CHECK: + /* any action other than APPRAISE is unsupported */ + if (entry->action != APPRAISE) + return false; + + /* SETXATTR_CHECK requires an appraise_algos parameter */ + if (!(entry->flags & IMA_VALIDATE_ALGOS)) + return false; + + /* + * full policies are not supported, they would have too + * much of a performance impact + */ + if (entry->flags & ~(IMA_FUNC | IMA_VALIDATE_ALGOS)) + return false; + + break; default: return false; } @@ -1173,6 +1243,34 @@ static bool ima_validate_rule(struct ima_rule_entry *entry) return true; } +static unsigned int ima_parse_appraise_algos(char *arg) +{ + unsigned int res = 0; + int idx; + char *token; + + while ((token = strsep(&arg, ",")) != NULL) { + idx = match_string(hash_algo_name, HASH_ALGO__LAST, token); + + if (idx < 0) { + pr_err("unknown hash algorithm \"%s\"", + token); + return 0; + } + + if (!crypto_has_alg(hash_algo_name[idx], 0, 0)) { + pr_err("unavailable hash algorithm \"%s\", check your kernel configuration", + token); + return 0; + } + + /* Add the hash algorithm to the 'allowed' bitfield */ + res |= (1U << idx); + } + + return res; +} + static int ima_parse_rule(char *rule, struct ima_rule_entry *entry) { struct audit_buffer *ab; @@ -1294,6 +1392,8 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry) entry->func = KEY_CHECK; else if (strcmp(args[0].from, "CRITICAL_DATA") == 0) entry->func = CRITICAL_DATA; + else if (strcmp(args[0].from, "SETXATTR_CHECK") == 0) + entry->func = SETXATTR_CHECK; else result = -EINVAL; if (!result) @@ -1508,6 +1608,25 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry) else result = -EINVAL; break; + case Opt_appraise_algos: + ima_log_string(ab, "appraise_algos", args[0].from); + + if (entry->allowed_algos) { + result = -EINVAL; + break; + } + + entry->allowed_algos = + ima_parse_appraise_algos(args[0].from); + /* invalid or empty list of algorithms */ + if (!entry->allowed_algos) { + result = -EINVAL; + break; + } + + entry->flags |= IMA_VALIDATE_ALGOS; + + break; case Opt_permit_directio: entry->flags |= IMA_PERMIT_DIRECTIO; break; @@ -1700,6 +1819,23 @@ static void ima_show_rule_opt_list(struct seq_file *m, seq_printf(m, "%s%s", i ? "|" : "", opt_list->items[i]); } +static void ima_policy_show_appraise_algos(struct seq_file *m, + unsigned int allowed_hashes) +{ + int idx, list_size = 0; + + for (idx = 0; idx < HASH_ALGO__LAST; idx++) { + if (!(allowed_hashes & (1U << idx))) + continue; + + /* only add commas if the list contains multiple entries */ + if (list_size++) + seq_puts(m, ","); + + seq_puts(m, hash_algo_name[idx]); + } +} + int ima_policy_show(struct seq_file *m, void *v) { struct ima_rule_entry *entry = v; @@ -1811,6 +1947,12 @@ int ima_policy_show(struct seq_file *m, void *v) seq_puts(m, " "); } + if (entry->flags & IMA_VALIDATE_ALGOS) { + seq_puts(m, "appraise_algos="); + ima_policy_show_appraise_algos(m, entry->allowed_algos); + seq_puts(m, " "); + } + for (i = 0; i < MAX_LSM_RULES; i++) { if (entry->lsm[i].rule) { switch (i) { diff --git a/security/integrity/ima/ima_queue_keys.c b/security/integrity/ima/ima_queue_keys.c index 979ef6c71f3d..93056c03bf5a 100644 --- a/security/integrity/ima/ima_queue_keys.c +++ b/security/integrity/ima/ima_queue_keys.c @@ -165,7 +165,7 @@ void ima_process_queued_keys(void) entry->keyring_name, KEY_CHECK, 0, entry->keyring_name, - false); + false, NULL, 0); list_del(&entry->list); ima_free_key_entry(entry); } diff --git a/security/selinux/ima.c b/security/selinux/ima.c index 34d421861bfc..727c4e43219d 100644 --- a/security/selinux/ima.c +++ b/security/selinux/ima.c @@ -86,7 +86,8 @@ void selinux_ima_measure_state_locked(struct selinux_state *state) } ima_measure_critical_data("selinux", "selinux-state", - state_str, strlen(state_str), false); + state_str, strlen(state_str), false, + NULL, 0); kfree(state_str); @@ -103,7 +104,8 @@ void selinux_ima_measure_state_locked(struct selinux_state *state) } ima_measure_critical_data("selinux", "selinux-policy-hash", - policy, policy_len, true); + policy, policy_len, true, + NULL, 0); vfree(policy); } |