Messages in this thread | | | Subject | Re: [PATCH v22 07/12] landlock: Support filesystem access-control | From | Mickaël Salaün <> | Date | Tue, 3 Nov 2020 17:03:45 +0100 |
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On 29/10/2020 02:06, Jann Horn wrote: > (On Tue, Oct 27, 2020 at 9:04 PM Mickaël Salaün <mic@digikod.net> wrote:
>> diff --git a/security/landlock/fs.c b/security/landlock/fs.c > [...] >> +static inline u32 get_file_access(const struct file *const file) >> +{ >> + u32 access = 0; >> + >> + if (file->f_mode & FMODE_READ) { >> + /* A directory can only be opened in read mode. */ >> + if (S_ISDIR(file_inode(file)->i_mode)) >> + return LANDLOCK_ACCESS_FS_READ_DIR; >> + access = LANDLOCK_ACCESS_FS_READ_FILE; >> + } >> + /* >> + * A LANDLOCK_ACCESS_FS_APPEND could be added but we also need to check >> + * fcntl(2). >> + */ > > Once https://lore.kernel.org/linux-api/20200831153207.GO3265@brightrain.aerifal.cx/ > lands, pwritev2() with RWF_NOAPPEND will also be problematic for > classifying "write" vs "append"; you may want to include that in the > comment. (Or delete the comment.)
Contrary to fcntl(2), pwritev2(2) doesn't seems to modify the file description. Otherwise, other LSMs would need to be patched. I'll remove this comment anyway.
> >> + if (file->f_mode & FMODE_WRITE) >> + access |= LANDLOCK_ACCESS_FS_WRITE_FILE; >> + /* __FMODE_EXEC is indeed part of f_flags, not f_mode. */ >> + if (file->f_flags & __FMODE_EXEC) >> + access |= LANDLOCK_ACCESS_FS_EXECUTE; >> + return access; >> +} > [...] >
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