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* [PATCH] ima: add gid support
@ 2021-07-02 22:20 Alex Henrie
  2021-09-01  2:12 ` Alex Henrie
  0 siblings, 1 reply; 4+ messages in thread
From: Alex Henrie @ 2021-07-02 22:20 UTC (permalink / raw)
  To: linux-integrity, zohar, alexhenrie24; +Cc: Curtis Veit, Alex Henrie

From: Curtis Veit <veit@vpieng.com>

IMA currently supports the concept of rules based on uid where the rule
is based on the uid of the file owner or the uid of the user accessing
the file. It is useful to have similar rules based on gid. This patch
provides that ability.

Signed-off-by: Curtis Veit <veit@vpieng.com>
Co-developed-by: Alex Henrie <alexh@vpitech.com>
Signed-off-by: Alex Henrie <alexh@vpitech.com>
---
This is the patch that Curtis sent in 2015,[1] rebased and with support
for effective GID and the new greater-than and less-than operators.
Moreover, the policy_opt enum is now in the same order as the
policy_tokens array, which I'm guessing is the bug that prevented the
patch from being accepted before.

[1] https://sourceforge.net/p/linux-ima/mailman/message/34210250/
---
 Documentation/ABI/testing/ima_policy |   5 +-
 security/integrity/ima/ima_policy.c  | 197 +++++++++++++++++++++++----
 2 files changed, 174 insertions(+), 28 deletions(-)

diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy
index 070779e8d836..28f2a5948bdd 100644
--- a/Documentation/ABI/testing/ima_policy
+++ b/Documentation/ABI/testing/ima_policy
@@ -23,7 +23,7 @@ Description:
 			  audit | hash | dont_hash
 		  condition:= base | lsm  [option]
 			base:	[[func=] [mask=] [fsmagic=] [fsuuid=] [uid=]
-				[euid=] [fowner=] [fsname=]]
+				[euid=] [gid=] [egid=] [fowner=] [fgroup=] [fsname=]]
 			lsm:	[[subj_user=] [subj_role=] [subj_type=]
 				 [obj_user=] [obj_role=] [obj_type=]]
 			option:	[[appraise_type=]] [template=] [permit_directio]
@@ -39,7 +39,10 @@ Description:
 			fsuuid:= file system UUID (e.g 8bcbe394-4f13-4144-be8e-5aa9ea2ce2f6)
 			uid:= decimal value
 			euid:= decimal value
+			gid:= decimal value
+			egid:= decimal value
 			fowner:= decimal value
+			fgroup:= decimal value
 		  lsm:  are LSM specific
 		  option:
 			appraise_type:= [imasig] [imasig|modsig]
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index fd5d46e511f1..9f8ac5c34baf 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -35,6 +35,9 @@
 #define IMA_FSNAME	0x0200
 #define IMA_KEYRINGS	0x0400
 #define IMA_LABEL	0x0800
+#define IMA_GID		0x1000
+#define IMA_EGID	0x2000
+#define IMA_FGROUP	0x4000
 
 #define UNKNOWN		0
 #define MEASURE		0x0001	/* same as IMA_MEASURE */
@@ -75,9 +78,13 @@ struct ima_rule_entry {
 	unsigned long fsmagic;
 	uuid_t fsuuid;
 	kuid_t uid;
+	kgid_t gid;
 	kuid_t fowner;
+	kgid_t fgroup;
 	bool (*uid_op)(kuid_t, kuid_t);    /* Handlers for operators       */
+	bool (*gid_op)(kgid_t, kgid_t);
 	bool (*fowner_op)(kuid_t, kuid_t); /* uid_eq(), uid_gt(), uid_lt() */
+	bool (*fgroup_op)(kgid_t, kgid_t); /* gid_eq(), gid_gt(), gid_lt() */
 	int pcr;
 	struct {
 		void *rule;	/* LSM file metadata specific */
@@ -92,7 +99,8 @@ struct ima_rule_entry {
 
 /*
  * Without LSM specific knowledge, the default policy can only be
- * written in terms of .action, .func, .mask, .fsmagic, .uid, and .fowner
+ * written in terms of .action, .func, .mask, .fsmagic, .uid, .gid,
+ * .fowner, and .fgroup
  */
 
 /*
@@ -570,10 +578,23 @@ static bool ima_match_rules(struct ima_rule_entry *rule,
 		} else if (!rule->uid_op(cred->euid, rule->uid))
 			return false;
 	}
-
+	if ((rule->flags & IMA_GID) && !rule->gid_op(rule->gid, cred->gid))
+		return false;
+	if (rule->flags & IMA_EGID) {
+		if (has_capability_noaudit(current, CAP_SETGID)) {
+			if (!rule->gid_op(cred->egid, rule->gid)
+			    && !rule->gid_op(cred->sgid, rule->gid)
+			    && !rule->gid_op(cred->gid, rule->gid))
+				return false;
+		} else if (!rule->gid_op(cred->egid, rule->gid))
+			return false;
+	}
 	if ((rule->flags & IMA_FOWNER) &&
 	    !rule->fowner_op(i_uid_into_mnt(mnt_userns, inode), rule->fowner))
 		return false;
+	if ((rule->flags & IMA_FGROUP) &&
+	    !rule->fgroup_op(i_gid_into_mnt(mnt_userns, inode), rule->fgroup))
+		return false;
 	for (i = 0; i < MAX_LSM_RULES; i++) {
 		int rc = 0;
 		u32 osid;
@@ -936,16 +957,19 @@ void ima_update_policy(void)
 }
 
 /* Keep the enumeration in sync with the policy_tokens! */
-enum {
+enum policy_opt {
 	Opt_measure, Opt_dont_measure,
 	Opt_appraise, Opt_dont_appraise,
 	Opt_audit, Opt_hash, Opt_dont_hash,
 	Opt_obj_user, Opt_obj_role, Opt_obj_type,
 	Opt_subj_user, Opt_subj_role, Opt_subj_type,
-	Opt_func, Opt_mask, Opt_fsmagic, Opt_fsname,
-	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_func, Opt_mask, Opt_fsmagic, Opt_fsname, Opt_fsuuid,
+	Opt_uid_eq, Opt_euid_eq, Opt_gid_eq, Opt_egid_eq,
+	Opt_fowner_eq, Opt_fgroup_eq,
+	Opt_uid_gt, Opt_euid_gt, Opt_gid_gt, Opt_egid_gt,
+	Opt_fowner_gt, Opt_fgroup_gt,
+	Opt_uid_lt, Opt_euid_lt, Opt_gid_lt, Opt_egid_lt,
+	Opt_fowner_lt, Opt_fgroup_lt,
 	Opt_appraise_type, Opt_appraise_flag,
 	Opt_permit_directio, Opt_pcr, Opt_template, Opt_keyrings,
 	Opt_label, Opt_err
@@ -972,13 +996,22 @@ static const match_table_t policy_tokens = {
 	{Opt_fsuuid, "fsuuid=%s"},
 	{Opt_uid_eq, "uid=%s"},
 	{Opt_euid_eq, "euid=%s"},
+	{Opt_gid_eq, "gid=%s"},
+	{Opt_egid_eq, "egid=%s"},
 	{Opt_fowner_eq, "fowner=%s"},
+	{Opt_fgroup_eq, "fgroup=%s"},
 	{Opt_uid_gt, "uid>%s"},
 	{Opt_euid_gt, "euid>%s"},
+	{Opt_gid_gt, "gid>%s"},
+	{Opt_egid_gt, "egid>%s"},
 	{Opt_fowner_gt, "fowner>%s"},
+	{Opt_fgroup_gt, "fgroup>%s"},
 	{Opt_uid_lt, "uid<%s"},
 	{Opt_euid_lt, "euid<%s"},
+	{Opt_gid_lt, "gid<%s"},
+	{Opt_egid_lt, "egid<%s"},
 	{Opt_fowner_lt, "fowner<%s"},
+	{Opt_fgroup_lt, "fgroup<%s"},
 	{Opt_appraise_type, "appraise_type=%s"},
 	{Opt_appraise_flag, "appraise_flag=%s"},
 	{Opt_permit_directio, "permit_directio"},
@@ -1021,22 +1054,36 @@ static int ima_lsm_rule_init(struct ima_rule_entry *entry,
 }
 
 static void ima_log_string_op(struct audit_buffer *ab, char *key, char *value,
-			      bool (*rule_operator)(kuid_t, kuid_t))
+			      enum policy_opt rule_operator)
 {
 	if (!ab)
 		return;
 
-	if (rule_operator == &uid_gt)
+	switch (rule_operator) {
+	case Opt_uid_gt:
+	case Opt_euid_gt:
+	case Opt_gid_gt:
+	case Opt_egid_gt:
+	case Opt_fowner_gt:
+	case Opt_fgroup_gt:
 		audit_log_format(ab, "%s>", key);
-	else if (rule_operator == &uid_lt)
+		break;
+	case Opt_uid_lt:
+	case Opt_euid_lt:
+	case Opt_gid_lt:
+	case Opt_egid_lt:
+	case Opt_fowner_lt:
+	case Opt_fgroup_lt:
 		audit_log_format(ab, "%s<", key);
-	else
+		break;
+	default:
 		audit_log_format(ab, "%s=", key);
+	}
 	audit_log_format(ab, "%s ", value);
 }
 static void ima_log_string(struct audit_buffer *ab, char *key, char *value)
 {
-	ima_log_string_op(ab, key, value, NULL);
+	ima_log_string_op(ab, key, value, Opt_err);
 }
 
 /*
@@ -1110,7 +1157,8 @@ static bool ima_validate_rule(struct ima_rule_entry *entry)
 		if (entry->flags & ~(IMA_FUNC | IMA_MASK | IMA_FSMAGIC |
 				     IMA_UID | IMA_FOWNER | IMA_FSUUID |
 				     IMA_INMASK | IMA_EUID | IMA_PCR |
-				     IMA_FSNAME | IMA_DIGSIG_REQUIRED |
+				     IMA_FSNAME | IMA_GID | IMA_EGID |
+				     IMA_FGROUP | IMA_DIGSIG_REQUIRED |
 				     IMA_PERMIT_DIRECTIO))
 			return false;
 
@@ -1121,7 +1169,8 @@ static bool ima_validate_rule(struct ima_rule_entry *entry)
 		if (entry->flags & ~(IMA_FUNC | IMA_MASK | IMA_FSMAGIC |
 				     IMA_UID | IMA_FOWNER | IMA_FSUUID |
 				     IMA_INMASK | IMA_EUID | IMA_PCR |
-				     IMA_FSNAME | IMA_DIGSIG_REQUIRED |
+				     IMA_FSNAME | IMA_GID | IMA_EGID |
+				     IMA_FGROUP | IMA_DIGSIG_REQUIRED |
 				     IMA_PERMIT_DIRECTIO | IMA_MODSIG_ALLOWED |
 				     IMA_CHECK_BLACKLIST))
 			return false;
@@ -1133,7 +1182,8 @@ static bool ima_validate_rule(struct ima_rule_entry *entry)
 
 		if (entry->flags & ~(IMA_FUNC | IMA_FSMAGIC | IMA_UID |
 				     IMA_FOWNER | IMA_FSUUID | IMA_EUID |
-				     IMA_PCR | IMA_FSNAME))
+				     IMA_PCR | IMA_FSNAME | IMA_GID | IMA_EGID |
+				     IMA_FGROUP))
 			return false;
 
 		break;
@@ -1142,7 +1192,7 @@ static bool ima_validate_rule(struct ima_rule_entry *entry)
 			return false;
 
 		if (entry->flags & ~(IMA_FUNC | IMA_UID | IMA_PCR |
-				     IMA_KEYRINGS))
+				     IMA_KEYRINGS | IMA_GID))
 			return false;
 
 		if (ima_rule_contains_lsm_cond(entry))
@@ -1154,7 +1204,7 @@ static bool ima_validate_rule(struct ima_rule_entry *entry)
 			return false;
 
 		if (entry->flags & ~(IMA_FUNC | IMA_UID | IMA_PCR |
-				     IMA_LABEL))
+				     IMA_LABEL | IMA_GID))
 			return false;
 
 		if (ima_rule_contains_lsm_cond(entry))
@@ -1178,7 +1228,7 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
 	struct audit_buffer *ab;
 	char *from;
 	char *p;
-	bool uid_token;
+	bool eid_token;
 	struct ima_template_desc *template_desc;
 	int result = 0;
 
@@ -1186,9 +1236,13 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
 				       AUDIT_INTEGRITY_POLICY_RULE);
 
 	entry->uid = INVALID_UID;
+	entry->gid = INVALID_GID;
 	entry->fowner = INVALID_UID;
+	entry->fgroup = INVALID_GID;
 	entry->uid_op = &uid_eq;
+	entry->gid_op = &gid_eq;
 	entry->fowner_op = &uid_eq;
+	entry->fgroup_op = &gid_eq;
 	entry->action = UNKNOWN;
 	while ((p = strsep(&rule, " \t")) != NULL) {
 		substring_t args[MAX_OPT_ARGS];
@@ -1404,12 +1458,12 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
 			fallthrough;
 		case Opt_uid_eq:
 		case Opt_euid_eq:
-			uid_token = (token == Opt_uid_eq) ||
-				    (token == Opt_uid_gt) ||
-				    (token == Opt_uid_lt);
+			eid_token = (token == Opt_euid_eq) ||
+				    (token == Opt_euid_gt) ||
+				    (token == Opt_euid_lt);
 
-			ima_log_string_op(ab, uid_token ? "uid" : "euid",
-					  args[0].from, entry->uid_op);
+			ima_log_string_op(ab, eid_token ? "euid" : "uid",
+					  args[0].from, token);
 
 			if (uid_valid(entry->uid)) {
 				result = -EINVAL;
@@ -1424,8 +1478,41 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
 				    (uid_t)lnum != lnum)
 					result = -EINVAL;
 				else
-					entry->flags |= uid_token
-					    ? IMA_UID : IMA_EUID;
+					entry->flags |= eid_token
+					    ? IMA_EUID : IMA_UID;
+			}
+			break;
+		case Opt_gid_gt:
+		case Opt_egid_gt:
+			entry->gid_op = &gid_gt;
+			fallthrough;
+		case Opt_gid_lt:
+		case Opt_egid_lt:
+			if ((token == Opt_gid_lt) || (token == Opt_egid_lt))
+				entry->gid_op = &gid_lt;
+			fallthrough;
+		case Opt_gid_eq:
+		case Opt_egid_eq:
+			eid_token = (token == Opt_egid_eq) ||
+				    (token == Opt_egid_gt) ||
+				    (token == Opt_egid_lt);
+
+			ima_log_string_op(ab, eid_token ? "egid" : "gid",
+					  args[0].from, token);
+
+			if (gid_valid(entry->gid)) {
+				result = -EINVAL;
+				break;
+			}
+
+			result = kstrtoul(args[0].from, 10, &lnum);
+			if (!result) {
+				entry->gid = make_kgid(current_user_ns(), (gid_t)lnum);
+				if (!gid_valid(entry->gid) || (((gid_t)lnum) != lnum))
+					result = -EINVAL;
+				else
+					entry->flags |= eid_token
+					    ? IMA_EGID : IMA_GID;
 			}
 			break;
 		case Opt_fowner_gt:
@@ -1436,8 +1523,7 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
 				entry->fowner_op = &uid_lt;
 			fallthrough;
 		case Opt_fowner_eq:
-			ima_log_string_op(ab, "fowner", args[0].from,
-					  entry->fowner_op);
+			ima_log_string_op(ab, "fowner", args[0].from, token);
 
 			if (uid_valid(entry->fowner)) {
 				result = -EINVAL;
@@ -1453,6 +1539,30 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
 					entry->flags |= IMA_FOWNER;
 			}
 			break;
+		case Opt_fgroup_gt:
+			entry->fgroup_op = &gid_gt;
+			fallthrough;
+		case Opt_fgroup_lt:
+			if (token == Opt_fgroup_lt)
+				entry->fgroup_op = &gid_lt;
+			fallthrough;
+		case Opt_fgroup_eq:
+			ima_log_string_op(ab, "fgroup", args[0].from, token);
+
+			if (gid_valid(entry->fgroup)) {
+				result = -EINVAL;
+				break;
+			}
+
+			result = kstrtoul(args[0].from, 10, &lnum);
+			if (!result) {
+				entry->fgroup = make_kgid(current_user_ns(), (gid_t)lnum);
+				if (!gid_valid(entry->fgroup) || (((gid_t)lnum) != lnum))
+					result = -EINVAL;
+				else
+					entry->flags |= IMA_FGROUP;
+			}
+			break;
 		case Opt_obj_user:
 			ima_log_string(ab, "obj_user", args[0].from);
 			result = ima_lsm_rule_init(entry, args,
@@ -1800,6 +1910,28 @@ int ima_policy_show(struct seq_file *m, void *v)
 		seq_puts(m, " ");
 	}
 
+	if (entry->flags & IMA_GID) {
+		snprintf(tbuf, sizeof(tbuf), "%d", __kgid_val(entry->gid));
+		if (entry->gid_op == &gid_gt)
+			seq_printf(m, pt(Opt_gid_gt), tbuf);
+		else if (entry->gid_op == &gid_lt)
+			seq_printf(m, pt(Opt_gid_lt), tbuf);
+		else
+			seq_printf(m, pt(Opt_gid_eq), tbuf);
+		seq_puts(m, " ");
+	}
+
+	if (entry->flags & IMA_EGID) {
+		snprintf(tbuf, sizeof(tbuf), "%d", __kgid_val(entry->gid));
+		if (entry->gid_op == &gid_gt)
+			seq_printf(m, pt(Opt_egid_gt), tbuf);
+		else if (entry->gid_op == &gid_lt)
+			seq_printf(m, pt(Opt_egid_lt), tbuf);
+		else
+			seq_printf(m, pt(Opt_egid_eq), tbuf);
+		seq_puts(m, " ");
+	}
+
 	if (entry->flags & IMA_FOWNER) {
 		snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->fowner));
 		if (entry->fowner_op == &uid_gt)
@@ -1811,6 +1943,17 @@ int ima_policy_show(struct seq_file *m, void *v)
 		seq_puts(m, " ");
 	}
 
+	if (entry->flags & IMA_FGROUP) {
+		snprintf(tbuf, sizeof(tbuf), "%d", __kgid_val(entry->fgroup));
+		if (entry->fgroup_op == &gid_gt)
+			seq_printf(m, pt(Opt_fgroup_gt), tbuf);
+		else if (entry->fgroup_op == &gid_lt)
+			seq_printf(m, pt(Opt_fgroup_lt), tbuf);
+		else
+			seq_printf(m, pt(Opt_fgroup_eq), tbuf);
+		seq_puts(m, " ");
+	}
+
 	for (i = 0; i < MAX_LSM_RULES; i++) {
 		if (entry->lsm[i].rule) {
 			switch (i) {
-- 
2.32.0


^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [PATCH] ima: add gid support
  2021-07-02 22:20 [PATCH] ima: add gid support Alex Henrie
@ 2021-09-01  2:12 ` Alex Henrie
  2021-09-01 14:54   ` Mimi Zohar
  0 siblings, 1 reply; 4+ messages in thread
From: Alex Henrie @ 2021-09-01  2:12 UTC (permalink / raw)
  To: Alex Henrie; +Cc: linux-integrity, zohar, alexhenrie24

Hello, could I get some feedback on this patch? Are there any
objections to including it upstream?

-Alex

^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [PATCH] ima: add gid support
  2021-09-01  2:12 ` Alex Henrie
@ 2021-09-01 14:54   ` Mimi Zohar
  2021-09-08 21:20     ` Alex Henrie
  0 siblings, 1 reply; 4+ messages in thread
From: Mimi Zohar @ 2021-09-01 14:54 UTC (permalink / raw)
  To: Alex Henrie; +Cc: linux-integrity, alexhenrie24

Hi Alex,

On Tue, 2021-08-31 at 20:12 -0600, Alex Henrie wrote:
> Hello, could I get some feedback on this patch? Are there any
> objections to including it upstream?

Conceptually I don't have a problem with the patch, but I'd also like a
test to go with it.  

Roberto posted "ima-evm-utils: Add UML support and tests for EVM
portable signatures", which introduces using UML (User Mode Linux) for
testing new kernel features, which, unfortunately, still needs to be
reviewed and upstreamed.  (Hint, hint help with reviewing.]

Another option is to define an LTP test.   In either case, a custom IMA
policy would be defined in terms of a loopback mounted filesystem to
avoid affecting the entire system.

I'd appreciate your re-basing and re-posting this patch.

thanks,

Mimi


^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [PATCH] ima: add gid support
  2021-09-01 14:54   ` Mimi Zohar
@ 2021-09-08 21:20     ` Alex Henrie
  0 siblings, 0 replies; 4+ messages in thread
From: Alex Henrie @ 2021-09-08 21:20 UTC (permalink / raw)
  To: Mimi Zohar; +Cc: linux-integrity, alexhenrie24

On Wed, 01 Sep 2021 10:54:21 -0400
Mimi Zohar <zohar@linux.ibm.com> wrote:

> Hi Alex,
> 
> On Tue, 2021-08-31 at 20:12 -0600, Alex Henrie wrote:
> > Hello, could I get some feedback on this patch? Are there any
> > objections to including it upstream?
> 
> Conceptually I don't have a problem with the patch, but I'd also like a
> test to go with it.  
> 
> Roberto posted "ima-evm-utils: Add UML support and tests for EVM
> portable signatures", which introduces using UML (User Mode Linux) for
> testing new kernel features, which, unfortunately, still needs to be
> reviewed and upstreamed.  (Hint, hint help with reviewing.]
> 
> Another option is to define an LTP test.   In either case, a custom IMA
> policy would be defined in terms of a loopback mounted filesystem to
> avoid affecting the entire system.
> 
> I'd appreciate your re-basing and re-posting this patch.
> 
> thanks,
> 
> Mimi
> 

Thanks for the feedback! The UML tests are intriguing and I will be
interested to see how they work out. However, I think the tests for
this particular patch fit better with the existing LTP tests. I will
send a rebased kernel patch and an LTP patch.

-Alex

^ permalink raw reply	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2021-09-08 21:21 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2021-09-01  2:12 ` Alex Henrie
2021-09-01 14:54   ` Mimi Zohar
2021-09-08 21:20     ` Alex Henrie

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