Re: [PATCH v1 05/11] landlock: Move filesystem helpers and add a new one
From: Paul Moore <paul@paul-moore.com>
Date: 2022-03-17 01:27:04
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linux-doc, linux-fsdevel, lkml
On Mon, Feb 21, 2022 at 4:15 PM Mickaël Salaün [off-list ref] wrote:
From: Mickaël Salaün <redacted> 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. Signed-off-by: Mickaël Salaün <redacted> Link: https://lore.kernel.org/r/20220221212522.320243-6-mic@digikod.net (local) --- security/landlock/fs.c | 87 ++++++++++++++++++++++-------------------- 1 file changed, 46 insertions(+), 41 deletions(-)
One nit-picky comment below, otherwise it looks fine to me. Reviewed-by: Paul Moore <paul@paul-moore.com>
quoted hunk ↗ jump to hunk
diff --git a/security/landlock/fs.c b/security/landlock/fs.c index 9662f9fb3cd0..3886f9ad1a60 100644 --- a/security/landlock/fs.c +++ b/security/landlock/fs.c@@ -257,6 +257,18 @@ static inline bool unmask_layers(const struct landlock_rule *const rule, return false; } +static inline bool is_nouser_or_private(const struct dentry *dentry) +{ + /* + * 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> . + */
I might suggest moving this explanation up to a function header comment block.
+ 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)-- paul-moore.com