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Message-ID: <20220309134459.6448-3-konstantin.meskhidze@huawei.com>
Date: Wed, 9 Mar 2022 21:44:46 +0800
From: Konstantin Meskhidze <konstantin.meskhidze@...wei.com>
To: <mic@...ikod.net>
CC: <willemdebruijn.kernel@...il.com>,
<linux-security-module@...r.kernel.org>, <netdev@...r.kernel.org>,
<netfilter-devel@...r.kernel.org>, <yusongping@...wei.com>,
<artem.kuzin@...wei.com>, <anton.sirazetdinov@...wei.com>
Subject: [RFC PATCH v4 02/15] landlock: filesystem access mask helpers
This patch adds filesystem helper functions
to set and get filesystem mask. Also the modification
adds a helper structure landlock_access_mask to
support managing multiple access mask.
Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@...wei.com>
---
Changes since v3:
* Split commit.
* Add get_mask, set_mask helpers for filesystem.
* Add new struct landlock_access_mask.
---
security/landlock/fs.c | 4 ++--
security/landlock/ruleset.c | 20 +++++++++++++++++---
security/landlock/ruleset.h | 19 ++++++++++++++++++-
security/landlock/syscalls.c | 9 ++++++---
4 files changed, 43 insertions(+), 9 deletions(-)
diff --git a/security/landlock/fs.c b/security/landlock/fs.c
index d727bdab7840..97f5c455f5a7 100644
--- a/security/landlock/fs.c
+++ b/security/landlock/fs.c
@@ -163,7 +163,7 @@ int landlock_append_fs_rule(struct landlock_ruleset *const ruleset,
return -EINVAL;
/* Transforms relative access rights to absolute ones. */
- access_rights |= LANDLOCK_MASK_ACCESS_FS & ~ruleset->access_masks[0];
+ access_rights |= LANDLOCK_MASK_ACCESS_FS & ~landlock_get_fs_access_mask(ruleset, 0);
object = get_inode_object(d_backing_inode(path->dentry));
if (IS_ERR(object))
return PTR_ERR(object);
@@ -252,7 +252,7 @@ static int check_access_path(const struct landlock_ruleset *const domain,
/* Saves all layers handling a subset of requested accesses. */
layer_mask = 0;
for (i = 0; i < domain->num_layers; i++) {
- if (domain->access_masks[i] & access_request)
+ if (landlock_get_fs_access_mask(domain, i) & access_request)
layer_mask |= BIT_ULL(i);
}
/* An access request not handled by the domain is allowed. */
diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c
index 78341a0538de..a6212b752549 100644
--- a/security/landlock/ruleset.c
+++ b/security/landlock/ruleset.c
@@ -44,16 +44,30 @@ static struct landlock_ruleset *create_ruleset(const u32 num_layers)
return new_ruleset;
}
-struct landlock_ruleset *landlock_create_ruleset(const u32 access_mask)
+/* A helper function to set a filesystem mask */
+void landlock_set_fs_access_mask(struct landlock_ruleset *ruleset,
+ const struct landlock_access_mask *access_mask_set,
+ u16 mask_level)
+{
+ ruleset->access_masks[mask_level] = access_mask_set->fs;
+}
+
+/* A helper function to get a filesystem mask */
+u32 landlock_get_fs_access_mask(const struct landlock_ruleset *ruleset, u16 mask_level)
+{
+ return ruleset->access_masks[mask_level];
+}
+
+struct landlock_ruleset *landlock_create_ruleset(const struct landlock_access_mask *access_mask_set)
{
struct landlock_ruleset *new_ruleset;
/* Informs about useless ruleset. */
- if (!access_mask)
+ if (!access_mask_set->fs)
return ERR_PTR(-ENOMSG);
new_ruleset = create_ruleset(1);
if (!IS_ERR(new_ruleset))
- new_ruleset->access_masks[0] = access_mask;
+ landlock_set_fs_access_mask(new_ruleset, access_mask_set, 0);
return new_ruleset;
}
diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h
index 32d90ce72428..bc87e5f787f7 100644
--- a/security/landlock/ruleset.h
+++ b/security/landlock/ruleset.h
@@ -16,6 +16,16 @@
#include "object.h"
+/**
+ * struct landlock_access_mask - A helper structure to handle different mask types
+ */
+struct landlock_access_mask {
+ /**
+ * @fs: Filesystem access mask.
+ */
+ u16 fs;
+};
+
/**
* struct landlock_layer - Access rights for a given layer
*/
@@ -140,7 +150,8 @@ struct landlock_ruleset {
};
};
-struct landlock_ruleset *landlock_create_ruleset(const u32 access_mask);
+struct landlock_ruleset *landlock_create_ruleset(const struct landlock_access_mask
+ *access_mask_set);
void landlock_put_ruleset(struct landlock_ruleset *const ruleset);
void landlock_put_ruleset_deferred(struct landlock_ruleset *const ruleset);
@@ -162,4 +173,10 @@ static inline void landlock_get_ruleset(struct landlock_ruleset *const ruleset)
refcount_inc(&ruleset->usage);
}
+void landlock_set_fs_access_mask(struct landlock_ruleset *ruleset,
+ const struct landlock_access_mask *access_mask_set,
+ u16 mask_level);
+
+u32 landlock_get_fs_access_mask(const struct landlock_ruleset *ruleset, u16 mask_level);
+
#endif /* _SECURITY_LANDLOCK_RULESET_H */
diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c
index f1d86311df7e..5931b666321d 100644
--- a/security/landlock/syscalls.c
+++ b/security/landlock/syscalls.c
@@ -159,6 +159,7 @@ SYSCALL_DEFINE3(landlock_create_ruleset,
{
struct landlock_ruleset_attr ruleset_attr;
struct landlock_ruleset *ruleset;
+ struct landlock_access_mask access_mask_set = {.fs = 0};
int err, ruleset_fd;
/* Build-time checks. */
@@ -185,9 +186,10 @@ SYSCALL_DEFINE3(landlock_create_ruleset,
if ((ruleset_attr.handled_access_fs | LANDLOCK_MASK_ACCESS_FS) !=
LANDLOCK_MASK_ACCESS_FS)
return -EINVAL;
+ access_mask_set.fs = ruleset_attr.handled_access_fs;
/* Checks arguments and transforms to kernel struct. */
- ruleset = landlock_create_ruleset(ruleset_attr.handled_access_fs);
+ ruleset = landlock_create_ruleset(&access_mask_set);
if (IS_ERR(ruleset))
return PTR_ERR(ruleset);
@@ -343,8 +345,9 @@ SYSCALL_DEFINE4(landlock_add_rule,
* Checks that allowed_access matches the @ruleset constraints
* (ruleset->access_masks[0] is automatically upgraded to 64-bits).
*/
- if ((path_beneath_attr.allowed_access | ruleset->access_masks[0]) !=
- ruleset->access_masks[0]) {
+
+ if ((path_beneath_attr.allowed_access | landlock_get_fs_access_mask(ruleset, 0)) !=
+ landlock_get_fs_access_mask(ruleset, 0)) {
err = -EINVAL;
goto out_put_ruleset;
}
--
2.25.1
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