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authorMickaël Salaün <mic@digikod.net>2022-05-06 18:10:55 +0200
committerMickaël Salaün <mic@digikod.net>2022-05-23 13:27:58 +0200
commit9da82b20fde95814af721a2a7b1796a5b4a3d78e (patch)
treed75fd6cc64d4afce5ab8e4170f1b5a85503be383 /security/landlock
parent8ba0005ff418ec356e176b26eaa04a6ac755d05b (diff)
downloadlwn-9da82b20fde95814af721a2a7b1796a5b4a3d78e.tar.gz
lwn-9da82b20fde95814af721a2a7b1796a5b4a3d78e.zip
landlock: Move filesystem helpers and add a new one
Move the SB_NOUSER and IS_PRIVATE dentry check to a standalone is_nouser_or_private() helper. This will be useful for a following commit. Move get_mode_access() and maybe_remove() to make them usable by new code provided by a following commit. Reviewed-by: Paul Moore <paul@paul-moore.com> Signed-off-by: Mickaël Salaün <mic@digikod.net> Link: https://lore.kernel.org/r/20220506161102.525323-6-mic@digikod.net
Diffstat (limited to 'security/landlock')
-rw-r--r--security/landlock/fs.c87
1 files changed, 46 insertions, 41 deletions
diff --git a/security/landlock/fs.c b/security/landlock/fs.c
index c5749301b37d..7b7860039a08 100644
--- a/security/landlock/fs.c
+++ b/security/landlock/fs.c
@@ -261,6 +261,18 @@ unmask_layers(const struct landlock_rule *const rule,
return false;
}
+/*
+ * Allows access to pseudo filesystems that will never be mountable (e.g.
+ * sockfs, pipefs), but can still be reachable through
+ * /proc/<pid>/fd/<file-descriptor>
+ */
+static inline bool is_nouser_or_private(const struct dentry *dentry)
+{
+ return (dentry->d_sb->s_flags & SB_NOUSER) ||
+ (d_is_positive(dentry) &&
+ unlikely(IS_PRIVATE(d_backing_inode(dentry))));
+}
+
static int check_access_path(const struct landlock_ruleset *const domain,
const struct path *const path,
const access_mask_t access_request)
@@ -274,14 +286,7 @@ static int check_access_path(const struct landlock_ruleset *const domain,
return 0;
if (WARN_ON_ONCE(!domain || !path))
return 0;
- /*
- * Allows access to pseudo filesystems that will never be mountable
- * (e.g. sockfs, pipefs), but can still be reachable through
- * /proc/<pid>/fd/<file-descriptor> .
- */
- if ((path->dentry->d_sb->s_flags & SB_NOUSER) ||
- (d_is_positive(path->dentry) &&
- unlikely(IS_PRIVATE(d_backing_inode(path->dentry)))))
+ if (is_nouser_or_private(path->dentry))
return 0;
if (WARN_ON_ONCE(domain->num_layers < 1))
return -EACCES;
@@ -360,6 +365,39 @@ static inline int current_check_access_path(const struct path *const path,
return check_access_path(dom, path, access_request);
}
+static inline access_mask_t get_mode_access(const umode_t mode)
+{
+ switch (mode & S_IFMT) {
+ case S_IFLNK:
+ return LANDLOCK_ACCESS_FS_MAKE_SYM;
+ case 0:
+ /* A zero mode translates to S_IFREG. */
+ case S_IFREG:
+ return LANDLOCK_ACCESS_FS_MAKE_REG;
+ case S_IFDIR:
+ return LANDLOCK_ACCESS_FS_MAKE_DIR;
+ case S_IFCHR:
+ return LANDLOCK_ACCESS_FS_MAKE_CHAR;
+ case S_IFBLK:
+ return LANDLOCK_ACCESS_FS_MAKE_BLOCK;
+ case S_IFIFO:
+ return LANDLOCK_ACCESS_FS_MAKE_FIFO;
+ case S_IFSOCK:
+ return LANDLOCK_ACCESS_FS_MAKE_SOCK;
+ default:
+ WARN_ON_ONCE(1);
+ return 0;
+ }
+}
+
+static inline access_mask_t maybe_remove(const struct dentry *const dentry)
+{
+ if (d_is_negative(dentry))
+ return 0;
+ return d_is_dir(dentry) ? LANDLOCK_ACCESS_FS_REMOVE_DIR :
+ LANDLOCK_ACCESS_FS_REMOVE_FILE;
+}
+
/* Inode hooks */
static void hook_inode_free_security(struct inode *const inode)
@@ -553,31 +591,6 @@ static int hook_sb_pivotroot(const struct path *const old_path,
/* Path hooks */
-static inline access_mask_t get_mode_access(const umode_t mode)
-{
- switch (mode & S_IFMT) {
- case S_IFLNK:
- return LANDLOCK_ACCESS_FS_MAKE_SYM;
- case 0:
- /* A zero mode translates to S_IFREG. */
- case S_IFREG:
- return LANDLOCK_ACCESS_FS_MAKE_REG;
- case S_IFDIR:
- return LANDLOCK_ACCESS_FS_MAKE_DIR;
- case S_IFCHR:
- return LANDLOCK_ACCESS_FS_MAKE_CHAR;
- case S_IFBLK:
- return LANDLOCK_ACCESS_FS_MAKE_BLOCK;
- case S_IFIFO:
- return LANDLOCK_ACCESS_FS_MAKE_FIFO;
- case S_IFSOCK:
- return LANDLOCK_ACCESS_FS_MAKE_SOCK;
- default:
- WARN_ON_ONCE(1);
- return 0;
- }
-}
-
/*
* Creating multiple links or renaming may lead to privilege escalations if not
* handled properly. Indeed, we must be sure that the source doesn't gain more
@@ -606,14 +619,6 @@ static int hook_path_link(struct dentry *const old_dentry,
get_mode_access(d_backing_inode(old_dentry)->i_mode));
}
-static inline access_mask_t maybe_remove(const struct dentry *const dentry)
-{
- if (d_is_negative(dentry))
- return 0;
- return d_is_dir(dentry) ? LANDLOCK_ACCESS_FS_REMOVE_DIR :
- LANDLOCK_ACCESS_FS_REMOVE_FILE;
-}
-
static int hook_path_rename(const struct path *const old_dir,
struct dentry *const old_dentry,
const struct path *const new_dir,