The existing BPRM_CHECK functionality in IMA validates against the credentials of the existing process, not any new credentials that the child process may transition to. Add an additional CREDS_CHECK target and refactor IMA to pass the appropriate creds structure. In ima_bprm_check(), check with both the existing process credentials and the credentials that will be committed when the new process is started.
Signed-off-by: Matthew Garrett <[email protected]> Cc: Paul Moore <[email protected]> Cc: Stephen Smalley <[email protected]> Cc: Eric Paris <[email protected]> Cc: [email protected] Cc: Casey Schaufler <[email protected]> Cc: [email protected] Cc: Mimi Zohar <[email protected]> Cc: Dmitry Kasatkin <[email protected]> Cc: [email protected] --- V2: Fix the IMA_CRED_CHECK defines Documentation/ABI/testing/ima_policy | 2 +- security/integrity/iint.c | 1 + security/integrity/ima/ima.h | 7 ++++--- security/integrity/ima/ima_api.c | 8 +++++--- security/integrity/ima/ima_appraise.c | 10 +++++++++- security/integrity/ima/ima_main.c | 26 +++++++++++++++++--------- security/integrity/ima/ima_policy.c | 19 ++++++++++++------- security/integrity/integrity.h | 9 +++++++-- 8 files changed, 56 insertions(+), 26 deletions(-) diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy index e76432b9954d..5dc9eed035fb 100644 --- a/Documentation/ABI/testing/ima_policy +++ b/Documentation/ABI/testing/ima_policy @@ -25,7 +25,7 @@ Description: [obj_user=] [obj_role=] [obj_type=]] option: [[appraise_type=]] [permit_directio] - base: func:= [BPRM_CHECK][MMAP_CHECK][FILE_CHECK][MODULE_CHECK] + base: func:= [BPRM_CHECK][MMAP_CHECK][CREDS_CHECK][FILE_CHECK][MODULE_CHECK] [FIRMWARE_CHECK] [KEXEC_KERNEL_CHECK] [KEXEC_INITRAMFS_CHECK] mask:= [[^]MAY_READ] [[^]MAY_WRITE] [[^]MAY_APPEND] diff --git a/security/integrity/iint.c b/security/integrity/iint.c index 6fc888ca468e..ad30094a58b4 100644 --- a/security/integrity/iint.c +++ b/security/integrity/iint.c @@ -78,6 +78,7 @@ static void iint_free(struct integrity_iint_cache *iint) iint->ima_mmap_status = INTEGRITY_UNKNOWN; iint->ima_bprm_status = INTEGRITY_UNKNOWN; iint->ima_read_status = INTEGRITY_UNKNOWN; + iint->ima_creds_status = INTEGRITY_UNKNOWN; iint->evm_status = INTEGRITY_UNKNOWN; iint->measured_pcrs = 0; kmem_cache_free(iint_cache, iint); diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index d52b487ad259..0703a96072b5 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -177,6 +177,7 @@ static inline unsigned long ima_hash_key(u8 *digest) hook(FILE_CHECK) \ hook(MMAP_CHECK) \ hook(BPRM_CHECK) \ + hook(CREDS_CHECK) \ hook(POST_SETATTR) \ hook(MODULE_CHECK) \ hook(FIRMWARE_CHECK) \ @@ -191,7 +192,7 @@ enum ima_hooks { }; /* LIM API function definitions */ -int ima_get_action(struct inode *inode, int mask, +int ima_get_action(struct inode *inode, const struct cred *cred, int mask, enum ima_hooks func, int *pcr); int ima_must_measure(struct inode *inode, int mask, enum ima_hooks func); int ima_collect_measurement(struct integrity_iint_cache *iint, @@ -212,8 +213,8 @@ void ima_free_template_entry(struct ima_template_entry *entry); const char *ima_d_path(const struct path *path, char **pathbuf, char *filename); /* IMA policy related functions */ -int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask, - int flags, int *pcr); +int ima_match_policy(struct inode *inode, const struct cred *cred, + enum ima_hooks func, int mask, int flags, int *pcr); void ima_init_policy(void); void ima_update_policy(void); void ima_update_policy_flag(void); diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c index c2edba8de35e..ff33b7e65a07 100644 --- a/security/integrity/ima/ima_api.c +++ b/security/integrity/ima/ima_api.c @@ -157,6 +157,7 @@ void ima_add_violation(struct file *file, const unsigned char *filename, /** * ima_get_action - appraise & measure decision based on policy. * @inode: pointer to inode to measure + * @cred: pointer to credentials structure to validate * @mask: contains the permission mask (MAY_READ, MAY_WRITE, MAY_EXEC, * MAY_APPEND) * @func: caller identifier @@ -165,20 +166,21 @@ void ima_add_violation(struct file *file, const unsigned char *filename, * The policy is defined in terms of keypairs: * subj=, obj=, type=, func=, mask=, fsmagic= * subj,obj, and type: are LSM specific. - * func: FILE_CHECK | BPRM_CHECK | MMAP_CHECK | MODULE_CHECK + * func: FILE_CHECK | BPRM_CHECK | CREDS_CHECK | MMAP_CHECK | MODULE_CHECK * mask: contains the permission mask * fsmagic: hex value * * Returns IMA_MEASURE, IMA_APPRAISE mask. * */ -int ima_get_action(struct inode *inode, int mask, enum ima_hooks func, int *pcr) +int ima_get_action(struct inode *inode, const struct cred *cred, int mask, + enum ima_hooks func, int *pcr) { int flags = IMA_MEASURE | IMA_AUDIT | IMA_APPRAISE; flags &= ima_policy_flag; - return ima_match_policy(inode, func, mask, flags, pcr); + return ima_match_policy(inode, cred, func, mask, flags, pcr); } /* diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c index 809ba70fbbbf..137b8d1708c6 100644 --- a/security/integrity/ima/ima_appraise.c +++ b/security/integrity/ima/ima_appraise.c @@ -53,7 +53,8 @@ int ima_must_appraise(struct inode *inode, int mask, enum ima_hooks func) if (!ima_appraise) return 0; - return ima_match_policy(inode, func, mask, IMA_APPRAISE, NULL); + return ima_match_policy(inode, current_cred(), func, mask, + IMA_APPRAISE, NULL); } static int ima_fix_xattr(struct dentry *dentry, @@ -86,6 +87,8 @@ enum integrity_status ima_get_cache_status(struct integrity_iint_cache *iint, 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; @@ -106,6 +109,8 @@ static void ima_set_cache_status(struct integrity_iint_cache *iint, case BPRM_CHECK: iint->ima_bprm_status = status; break; + case CREDS_CHECK: + iint->ima_creds_status = status; case FILE_CHECK: case POST_SETATTR: iint->ima_file_status = status; @@ -127,6 +132,9 @@ static void ima_cache_flags(struct integrity_iint_cache *iint, 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); diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index 2aebb7984437..f41aa427792b 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -155,8 +155,9 @@ void ima_file_free(struct file *file) ima_check_last_writer(iint, inode, file); } -static int process_measurement(struct file *file, char *buf, loff_t size, - int mask, enum ima_hooks func, int opened) +static int process_measurement(struct file *file, const struct cred *cred, + char *buf, loff_t size, int mask, + enum ima_hooks func, int opened) { struct inode *inode = file_inode(file); struct integrity_iint_cache *iint = NULL; @@ -178,7 +179,7 @@ static int process_measurement(struct file *file, char *buf, loff_t size, * bitmask based on the appraise/audit/measurement policy. * Included is the appraise submask. */ - action = ima_get_action(inode, mask, func, &pcr); + action = ima_get_action(inode, cred, mask, func, &pcr); violation_check = ((func == FILE_CHECK || func == MMAP_CHECK) && (ima_policy_flag & IMA_MEASURE)); if (!action && !violation_check) @@ -282,8 +283,8 @@ static int process_measurement(struct file *file, char *buf, loff_t size, int ima_file_mmap(struct file *file, unsigned long prot) { if (file && (prot & PROT_EXEC)) - return process_measurement(file, NULL, 0, MAY_EXEC, - MMAP_CHECK, 0); + return process_measurement(file, current_cred(), NULL, 0, + MAY_EXEC, MMAP_CHECK, 0); return 0; } @@ -302,8 +303,14 @@ int ima_file_mmap(struct file *file, unsigned long prot) */ int ima_bprm_check(struct linux_binprm *bprm) { - return process_measurement(bprm->file, NULL, 0, MAY_EXEC, - BPRM_CHECK, 0); + int ret; + + ret = process_measurement(bprm->file, current_cred(), NULL, 0, + MAY_EXEC, BPRM_CHECK, 0); + if (ret) + return ret; + return process_measurement(bprm->file, bprm->cred, NULL, 0, + MAY_EXEC, CREDS_CHECK, 0); } /** @@ -318,7 +325,7 @@ int ima_bprm_check(struct linux_binprm *bprm) */ int ima_file_check(struct file *file, int mask, int opened) { - return process_measurement(file, NULL, 0, + return process_measurement(file, current_cred(), NULL, 0, mask & (MAY_READ | MAY_WRITE | MAY_EXEC | MAY_APPEND), FILE_CHECK, opened); } @@ -413,7 +420,8 @@ int ima_post_read_file(struct file *file, void *buf, loff_t size, } func = read_idmap[read_id] ?: FILE_CHECK; - return process_measurement(file, buf, size, MAY_READ, func, 0); + return process_measurement(file, current_cred(), buf, size, MAY_READ, + func, 0); } static int __init init_ima(void) diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c index 95209a5f8595..c9d5735711eb 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -247,10 +247,9 @@ static void ima_lsm_update_rules(void) * Returns true on rule match, false on failure. */ static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode, - enum ima_hooks func, int mask) + const struct cred *cred, enum ima_hooks func, + int mask) { - struct task_struct *tsk = current; - const struct cred *cred = current_cred(); int i; if ((rule->flags & IMA_FUNC) && @@ -305,7 +304,7 @@ static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode, case LSM_SUBJ_USER: case LSM_SUBJ_ROLE: case LSM_SUBJ_TYPE: - security_task_getsecid(tsk, &sid); + security_cred_getsecid(cred, &sid); rc = security_filter_rule_match(sid, rule->lsm[i].type, Audit_equal, @@ -339,6 +338,8 @@ static int get_subaction(struct ima_rule_entry *rule, enum ima_hooks func) return IMA_MMAP_APPRAISE; case BPRM_CHECK: return IMA_BPRM_APPRAISE; + case CREDS_CHECK: + return IMA_CREDS_APPRAISE; case FILE_CHECK: case POST_SETATTR: return IMA_FILE_APPRAISE; @@ -351,6 +352,8 @@ static int get_subaction(struct ima_rule_entry *rule, enum ima_hooks func) /** * ima_match_policy - decision based on LSM and other conditions * @inode: pointer to an inode for which the policy decision is being made + * @cred: pointer to a credentials structure for which the policy decision is + * being made * @func: IMA hook identifier * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC) * @pcr: set the pcr to extend @@ -362,8 +365,8 @@ static int get_subaction(struct ima_rule_entry *rule, enum ima_hooks func) * list when walking it. Reads are many orders of magnitude more numerous * than writes so ima_match_policy() is classical RCU candidate. */ -int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask, - int flags, int *pcr) +int ima_match_policy(struct inode *inode, const struct cred *cred, + enum ima_hooks func, int mask, int flags, int *pcr) { struct ima_rule_entry *entry; int action = 0, actmask = flags | (flags << 1); @@ -374,7 +377,7 @@ int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask, if (!(entry->action & actmask)) continue; - if (!ima_match_rules(entry, inode, func, mask)) + if (!ima_match_rules(entry, inode, cred, func, mask)) continue; action |= entry->flags & IMA_ACTION_FLAGS; @@ -691,6 +694,8 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry) entry->func = MMAP_CHECK; else if (strcmp(args[0].from, "BPRM_CHECK") == 0) entry->func = BPRM_CHECK; + else if (strcmp(args[0].from, "CREDS_CHECK") == 0) + entry->func = CREDS_CHECK; else if (strcmp(args[0].from, "KEXEC_KERNEL_CHECK") == 0) entry->func = KEXEC_KERNEL_CHECK; diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h index a53e7e4ab06c..45ba0e4501d6 100644 --- a/security/integrity/integrity.h +++ b/security/integrity/integrity.h @@ -48,10 +48,14 @@ #define IMA_BPRM_APPRAISED 0x00002000 #define IMA_READ_APPRAISE 0x00004000 #define IMA_READ_APPRAISED 0x00008000 +#define IMA_CREDS_APPRAISE 0x00010000 +#define IMA_CREDS_APPRAISED 0x00020000 #define IMA_APPRAISE_SUBMASK (IMA_FILE_APPRAISE | IMA_MMAP_APPRAISE | \ - IMA_BPRM_APPRAISE | IMA_READ_APPRAISE) + IMA_BPRM_APPRAISE | IMA_READ_APPRAISE | \ + IMA_CREDS_APPRAISE) #define IMA_APPRAISED_SUBMASK (IMA_FILE_APPRAISED | IMA_MMAP_APPRAISED | \ - IMA_BPRM_APPRAISED | IMA_READ_APPRAISED) + IMA_BPRM_APPRAISED | IMA_READ_APPRAISED | \ + IMA_CREDS_APPRAISED) enum evm_ima_xattr_type { IMA_XATTR_DIGEST = 0x01, @@ -108,6 +112,7 @@ struct integrity_iint_cache { enum integrity_status ima_mmap_status:4; enum integrity_status ima_bprm_status:4; enum integrity_status ima_read_status:4; + enum integrity_status ima_creds_status:4; enum integrity_status evm_status:4; struct ima_digest_data *ima_hash; }; -- 2.15.0.rc0.271.g36b669edcc-goog
