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-rw-r--r--security/integrity/ima/ima.h6
-rw-r--r--security/integrity/ima/ima_api.c6
-rw-r--r--security/integrity/ima/ima_appraise.c5
-rw-r--r--security/integrity/ima/ima_main.c18
-rw-r--r--security/integrity/ima/ima_policy.c18
5 files changed, 41 insertions, 12 deletions
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 829478dabeeb..bcaf818fb647 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -47,7 +47,7 @@ enum tpm_pcrs { TPM_PCR0 = 0, TPM_PCR8 = 8, TPM_PCR10 = 10 };
extern int ima_policy_flag;
/* 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;
@@ -254,7 +254,7 @@ 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,
@@ -285,7 +285,7 @@ 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);
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 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 baeb10efbf51..e2edef8a9185 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,
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 1cba6beb5a60..af6367ba34ee 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -215,6 +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;
@@ -224,7 +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)
@@ -361,6 +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))
@@ -438,7 +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)))
@@ -896,7 +908,7 @@ int 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);
+ func_data, NULL);
if (!(action & IMA_MEASURE) && !digest)
return -ENOENT;
}
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index fd5d46e511f1..1536e6f5eb22 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 */
@@ -79,6 +80,7 @@ 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 +93,14 @@ 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 +656,7 @@ 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 +669,7 @@ 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 +695,11 @@ 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);
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.