[v2,01/12] landlock: Define access_mask_t to enforce a consistent access mask size

Message ID	20220329125117.1393824-2-mic@digikod.net (mailing list archive)
State	New, archived
Headers	show Return-Path: <linux-security-module-owner@kernel.org> From: =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= <mic@digikod.net> To: James Morris <jmorris@namei.org>, "Serge E . Hallyn" <serge@hallyn.com> Cc: =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= <mic@digikod.net>, Al Viro <viro@zeniv.linux.org.uk>, Jann Horn <jannh@google.com>, John Johansen <john.johansen@canonical.com>, Kees Cook <keescook@chromium.org>, Konstantin Meskhidze <konstantin.meskhidze@huawei.com>, Paul Moore <paul@paul-moore.com>, Shuah Khan <shuah@kernel.org>, Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= <mic@linux.microsoft.com> Subject: [PATCH v2 01/12] landlock: Define access_mask_t to enforce a consistent access mask size Date: Tue, 29 Mar 2022 14:51:06 +0200 Message-Id: <20220329125117.1393824-2-mic@digikod.net> In-Reply-To: <20220329125117.1393824-1-mic@digikod.net> References: <20220329125117.1393824-1-mic@digikod.net> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk
Series	Landlock: file linking and renaming support \| expand [v2,00/12] Landlock: file linking and renaming support [v2,01/12] landlock: Define access_mask_t to enforce a consistent access mask size [v2,02/12] landlock: Reduce the maximum number of layers to 16 [v2,03/12] landlock: Create find_rule() from unmask_layers() [v2,04/12] landlock: Fix same-layer rule unions [v2,05/12] landlock: Move filesystem helpers and add a new one [v2,06/12] LSM: Remove double path_rename hook calls for RENAME_EXCHANGE [v2,07/12] landlock: Add support for file reparenting with LANDLOCK_ACCESS_FS_REFER [v2,08/12] selftest/landlock: Add 11 new test suites dedicated to file reparenting [v2,09/12] samples/landlock: Add support for file reparenting [v2,10/12] landlock: Document LANDLOCK_ACCESS_FS_REFER and ABI versioning [v2,11/12] landlock: Document good practices about filesystem policies [v2,12/12] landlock: Add design choices documentation for filesystem access rights

diff --git a/security/landlock/fs.c b/security/landlock/fs.c index 97b8e421f617..9de2a460a762 100644 --- a/security/landlock/fs.c +++ b/security/landlock/fs.c @@ -150,7 +150,7 @@ static struct landlock_object *get_inode_object(struct inode *const inode) * @path: Should have been checked by get_path_from_fd(). */ int landlock_append_fs_rule(struct landlock_ruleset *const ruleset, - const struct path *const path, u32 access_rights) + const struct path *const path, access_mask_t access_rights) { int err; struct landlock_object *object; @@ -182,8 +182,8 @@ int landlock_append_fs_rule(struct landlock_ruleset *const ruleset, static inline u64 unmask_layers( const struct landlock_ruleset *const domain, - const struct path *const path, const u32 access_request, - u64 layer_mask) + const struct path *const path, + const access_mask_t access_request, u64 layer_mask) { const struct landlock_rule *rule; const struct inode *inode; @@ -223,7 +223,8 @@ static inline u64 unmask_layers( } static int check_access_path(const struct landlock_ruleset *const domain, - const struct path *const path, u32 access_request) + const struct path *const path, + const access_mask_t access_request) { bool allowed = false; struct path walker_path; @@ -308,7 +309,7 @@ static int check_access_path(const struct landlock_ruleset *const domain, } static inline int current_check_access_path(const struct path *const path, - const u32 access_request) + const access_mask_t access_request) { const struct landlock_ruleset *const dom = landlock_get_current_domain(); @@ -511,7 +512,7 @@ static int hook_sb_pivotroot(const struct path *const old_path, /* Path hooks */ -static inline u32 get_mode_access(const umode_t mode) +static inline access_mask_t get_mode_access(const umode_t mode) { switch (mode & S_IFMT) { case S_IFLNK: @@ -563,7 +564,7 @@ static int hook_path_link(struct dentry *const old_dentry, get_mode_access(d_backing_inode(old_dentry)->i_mode)); } -static inline u32 maybe_remove(const struct dentry *const dentry) +static inline access_mask_t maybe_remove(const struct dentry *const dentry) { if (d_is_negative(dentry)) return 0; @@ -631,9 +632,9 @@ static int hook_path_rmdir(const struct path *const dir, /* File hooks */ -static inline u32 get_file_access(const struct file *const file) +static inline access_mask_t get_file_access(const struct file *const file) { - u32 access = 0; + access_mask_t access = 0; if (file->f_mode & FMODE_READ) { /* A directory can only be opened in read mode. */ diff --git a/security/landlock/fs.h b/security/landlock/fs.h index 187284b421c9..74be312aad96 100644 --- a/security/landlock/fs.h +++ b/security/landlock/fs.h @@ -65,6 +65,6 @@ static inline struct landlock_superblock_security *landlock_superblock( __init void landlock_add_fs_hooks(void); int landlock_append_fs_rule(struct landlock_ruleset *const ruleset, - const struct path *const path, u32 access_hierarchy); + const struct path *const path, access_mask_t access_hierarchy); #endif /* _SECURITY_LANDLOCK_FS_H */ diff --git a/security/landlock/limits.h b/security/landlock/limits.h index 2a0a1095ee27..458d1de32ed5 100644 --- a/security/landlock/limits.h +++ b/security/landlock/limits.h @@ -9,6 +9,7 @@ #ifndef _SECURITY_LANDLOCK_LIMITS_H #define _SECURITY_LANDLOCK_LIMITS_H +#include <linux/bitops.h> #include <linux/limits.h> #include <uapi/linux/landlock.h> @@ -17,5 +18,6 @@ #define LANDLOCK_LAST_ACCESS_FS LANDLOCK_ACCESS_FS_MAKE_SYM #define LANDLOCK_MASK_ACCESS_FS ((LANDLOCK_LAST_ACCESS_FS << 1) - 1) +#define LANDLOCK_NUM_ACCESS_FS __const_hweight64(LANDLOCK_MASK_ACCESS_FS) #endif /* _SECURITY_LANDLOCK_LIMITS_H */ diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c index ec72b9262bf3..4e7aa8024fff 100644 --- a/security/landlock/ruleset.c +++ b/security/landlock/ruleset.c @@ -44,7 +44,8 @@ static struct landlock_ruleset *create_ruleset(const u32 num_layers) return new_ruleset; } -struct landlock_ruleset *landlock_create_ruleset(const u32 fs_access_mask) +struct landlock_ruleset *landlock_create_ruleset( + const access_mask_t fs_access_mask) { struct landlock_ruleset *new_ruleset; @@ -228,7 +229,8 @@ static void build_check_layer(void) /* @ruleset must be locked by the caller. */ int landlock_insert_rule(struct landlock_ruleset *const ruleset, - struct landlock_object *const object, const u32 access) + struct landlock_object *const object, + const access_mask_t access) { struct landlock_layer layers[] = {{ .access = access, diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h index 2d3ed7ec5a0a..7e7cac68e443 100644 --- a/security/landlock/ruleset.h +++ b/security/landlock/ruleset.h @@ -9,13 +9,20 @@ #ifndef _SECURITY_LANDLOCK_RULESET_H #define _SECURITY_LANDLOCK_RULESET_H +#include <linux/bitops.h> +#include <linux/build_bug.h> #include <linux/mutex.h> #include <linux/rbtree.h> #include <linux/refcount.h> #include <linux/workqueue.h> +#include "limits.h" #include "object.h" +typedef u16 access_mask_t; +/* Makes sure all filesystem access rights can be stored. */ +static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_ACCESS_FS); + /** * struct landlock_layer - Access rights for a given layer */ @@ -28,7 +35,7 @@ struct landlock_layer { * @access: Bitfield of allowed actions on the kernel object. They are * relative to the object type (e.g. %LANDLOCK_ACTION_FS_READ). */ - u16 access; + access_mask_t access; }; /** @@ -135,18 +142,20 @@ struct landlock_ruleset { * layers are set once and never changed for the * lifetime of the ruleset. */ - u16 fs_access_masks[]; + access_mask_t fs_access_masks[]; }; }; }; -struct landlock_ruleset *landlock_create_ruleset(const u32 fs_access_mask); +struct landlock_ruleset *landlock_create_ruleset( + const access_mask_t fs_access_mask); void landlock_put_ruleset(struct landlock_ruleset *const ruleset); void landlock_put_ruleset_deferred(struct landlock_ruleset *const ruleset); int landlock_insert_rule(struct landlock_ruleset *const ruleset, - struct landlock_object *const object, const u32 access); + struct landlock_object *const object, + const access_mask_t access); struct landlock_ruleset *landlock_merge_ruleset( struct landlock_ruleset *const parent,

[v2,01/12] landlock: Define access_mask_t to enforce a consistent access mask size

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