From: Andreas Gruenbacher Subject: Re: [PATCH v23 07/22] richacl: Permission mapping functions Date: Mon, 11 Jul 2016 15:26:40 +0200 Message-ID: References: <1467294433-3222-1-git-send-email-agruenba@redhat.com> <1467294433-3222-8-git-send-email-agruenba@redhat.com> <1467725986.3800.22.camel@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Cc: Alexander Viro , Christoph Hellwig , "Theodore Ts'o" , Andreas Dilger , "J. Bruce Fields" , Trond Myklebust , Anna Schumaker , Dave Chinner , linux-ext4 , XFS Developers , LKML , linux-fsdevel , Linux NFS Mailing List , linux-cifs@vger.kernel.org, Linux API To: Jeff Layton Return-path: In-Reply-To: <1467725986.3800.22.camel@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Tue, Jul 5, 2016 at 3:39 PM, Jeff Layton wrote: > On Thu, 2016-06-30 at 15:46 +0200, Andreas Gruenbacher wrote: >> We need to map from POSIX permissions to NFSv4 permissions when a >> chmod() is done, from NFSv4 permissions to POSIX permissions when an acl >> is set (which implicitly sets the file permission bits), and from the >> MAY_READ/MAY_WRITE/MAY_EXEC/MAY_APPEND flags to NFSv4 permissions when >> doing an access check in a richacl. >> >> Signed-off-by: Andreas Gruenbacher >> Reviewed-by: J. Bruce Fields >> --- >> fs/richacl.c | 118 +++++++++++++++++++++++++++++++++++++++++++ >> include/linux/richacl.h | 3 ++ >> include/uapi/linux/richacl.h | 44 ++++++++++++++++ >> 3 files changed, 165 insertions(+) >> >> diff --git a/fs/richacl.c b/fs/richacl.c >> index bcc6591..d0a4135 100644 >> --- a/fs/richacl.c >> +++ b/fs/richacl.c >> @@ -63,3 +63,121 @@ richace_copy(struct richace *to, const struct richace *from) >> { >> memcpy(to, from, sizeof(struct richace)); >> } >> + >> +/* >> + * richacl_mask_to_mode - compute the file permission bits from mask >> + * @mask: %RICHACE_* permission mask >> + * >> + * Compute the file permission bits corresponding to a particular set of >> + * richacl permissions. >> + * >> + * See richacl_masks_to_mode(). >> + */ >> +static int >> +richacl_mask_to_mode(unsigned int mask) >> +{ >> + int mode = 0; >> + >> + if (mask & RICHACE_POSIX_MODE_READ) >> + mode |= S_IROTH; >> + if (mask & RICHACE_POSIX_MODE_WRITE) >> + mode |= S_IWOTH; >> + if (mask & RICHACE_POSIX_MODE_EXEC) >> + mode |= S_IXOTH; >> + >> + return mode; >> +} >> + >> +/** >> + * richacl_masks_to_mode - compute file permission bits from file masks >> + * >> + * When setting a richacl, we set the file permission bits to indicate maximum >> + * permissions: for example, we set the Write permission when a mask contains >> + * RICHACE_APPEND_DATA even if it does not also contain RICHACE_WRITE_DATA. >> + * >> + * Permissions which are not in RICHACE_POSIX_MODE_READ, >> + * RICHACE_POSIX_MODE_WRITE, or RICHACE_POSIX_MODE_EXEC cannot be represented >> + * in the file permission bits. Such permissions can still be effective, but >> + * not for new files or after a chmod(); they must be explicitly enabled in the >> + * richacl. >> + */ >> +int >> +richacl_masks_to_mode(const struct richacl *acl) >> +{ >> + return richacl_mask_to_mode(acl->a_owner_mask) << 6 | >> + richacl_mask_to_mode(acl->a_group_mask) << 3 | >> + richacl_mask_to_mode(acl->a_other_mask); >> +} >> +EXPORT_SYMBOL_GPL(richacl_masks_to_mode); >> + >> +/** >> + * richacl_mode_to_mask - compute a file mask from the lowest three mode bits >> + * @mode: mode to convert to richacl permissions >> + * >> + * When the file permission bits of a file are set with chmod(), this specifies >> + * the maximum permissions that processes will get. All permissions beyond >> + * that will be removed from the file masks, and become ineffective. >> + */ >> +unsigned int >> +richacl_mode_to_mask(umode_t mode) >> +{ >> + unsigned int mask = 0; >> + >> + if (mode & S_IROTH) >> + mask |= RICHACE_POSIX_MODE_READ; >> + if (mode & S_IWOTH) >> + mask |= RICHACE_POSIX_MODE_WRITE; >> + if (mode & S_IXOTH) >> + mask |= RICHACE_POSIX_MODE_EXEC; >> + >> + return mask; >> +} >> + >> +/** >> + * richacl_want_to_mask - convert the iop->permission want argument to a mask >> + * @want: @want argument of the permission inode operation >> + * >> + * When checking for append, @want is (MAY_WRITE | MAY_APPEND). >> + * >> + * Richacls use the iop->may_create and iop->may_delete hooks which are used >> + * for checking if creating and deleting files is allowed. These hooks do not >> + * use richacl_want_to_mask(), so we do not have to deal with mapping MAY_WRITE >> + * to RICHACE_ADD_FILE, RICHACE_ADD_SUBDIRECTORY, and RICHACE_DELETE_CHILD >> + * here. >> + */ > > This comment is confusing as I don't see any may_create or may_delete > iops in the final patchset. Do you mean may_create() and may_delete() > here? Since this is only called from richacl_permission, the comment doesn't make much sense anymore; removing. Also, richacl_want_to_mask can be turned into a static function. >> +unsigned int >> +richacl_want_to_mask(unsigned int want) >> +{ >> + unsigned int mask = 0; >> + >> + if (want & MAY_READ) >> + mask |= RICHACE_READ_DATA; >> + if (want & MAY_DELETE_SELF) >> + mask |= RICHACE_DELETE; >> + if (want & MAY_TAKE_OWNERSHIP) >> + mask |= RICHACE_WRITE_OWNER; >> + if (want & MAY_CHMOD) >> + mask |= RICHACE_WRITE_ACL; >> + if (want & MAY_SET_TIMES) >> + mask |= RICHACE_WRITE_ATTRIBUTES; >> + if (want & MAY_EXEC) >> + mask |= RICHACE_EXECUTE; >> + /* >> + * differentiate MAY_WRITE from these request >> + */ >> + if (want & (MAY_APPEND | >> + MAY_CREATE_FILE | MAY_CREATE_DIR | >> + MAY_DELETE_CHILD)) { >> + if (want & MAY_APPEND) >> + mask |= RICHACE_APPEND_DATA; >> + if (want & MAY_CREATE_FILE) >> + mask |= RICHACE_ADD_FILE; >> + if (want & MAY_CREATE_DIR) >> + mask |= RICHACE_ADD_SUBDIRECTORY; >> + if (want & MAY_DELETE_CHILD) >> + mask |= RICHACE_DELETE_CHILD; >> + } else if (want & MAY_WRITE) >> + mask |= RICHACE_WRITE_DATA; >> + return mask; >> +} >> +EXPORT_SYMBOL_GPL(richacl_want_to_mask); >> diff --git a/include/linux/richacl.h b/include/linux/richacl.h >> index edb8480..9102ef0 100644 >> --- a/include/linux/richacl.h >> +++ b/include/linux/richacl.h >> @@ -175,5 +175,8 @@ richace_is_same_identifier(const struct richace *a, const struct richace *b) >> extern struct richacl *richacl_alloc(int, gfp_t); >> extern struct richacl *richacl_clone(const struct richacl *, gfp_t); >> extern void richace_copy(struct richace *, const struct richace *); >> +extern int richacl_masks_to_mode(const struct richacl *); >> +extern unsigned int richacl_mode_to_mask(umode_t); >> +extern unsigned int richacl_want_to_mask(unsigned int); >> >> #endif /* __RICHACL_H */ >> diff --git a/include/uapi/linux/richacl.h b/include/uapi/linux/richacl.h >> index 08856f8..1ed48ac 100644 >> --- a/include/uapi/linux/richacl.h >> +++ b/include/uapi/linux/richacl.h >> @@ -96,4 +96,48 @@ >> RICHACE_WRITE_OWNER | \ >> RICHACE_SYNCHRONIZE ) >> >> +/* >> + * The POSIX permissions are supersets of the following richacl permissions: >> + * >> + * - MAY_READ maps to READ_DATA or LIST_DIRECTORY, depending on the type >> + * of the file system object. >> + * >> + * - MAY_WRITE maps to WRITE_DATA or RICHACE_APPEND_DATA for files, and to >> + * ADD_FILE, RICHACE_ADD_SUBDIRECTORY, or RICHACE_DELETE_CHILD for directories. >> + * >> + * - MAY_EXECUTE maps to RICHACE_EXECUTE. >> + * >> + * (Some of these richacl permissions have the same bit values.) >> + */ >> +#define RICHACE_POSIX_MODE_READ ( \ >> + RICHACE_READ_DATA | \ >> + RICHACE_LIST_DIRECTORY) >> +#define RICHACE_POSIX_MODE_WRITE ( \ >> + RICHACE_WRITE_DATA | \ >> + RICHACE_ADD_FILE | \ >> + RICHACE_APPEND_DATA | \ >> + RICHACE_ADD_SUBDIRECTORY | \ >> + RICHACE_DELETE_CHILD) >> +#define RICHACE_POSIX_MODE_EXEC RICHACE_EXECUTE >> +#define RICHACE_POSIX_MODE_ALL ( \ >> + RICHACE_POSIX_MODE_READ | \ >> + RICHACE_POSIX_MODE_WRITE | \ >> + RICHACE_POSIX_MODE_EXEC) >> + >> +/* >> + * These permissions are always allowed no matter what the acl says. >> + */ >> +#define RICHACE_POSIX_ALWAYS_ALLOWED ( \ >> + RICHACE_SYNCHRONIZE | \ >> + RICHACE_READ_ATTRIBUTES | \ >> + RICHACE_READ_ACL) >> + >> +/* >> + * The owner is implicitly granted these permissions under POSIX. >> + */ >> +#define RICHACE_POSIX_OWNER_ALLOWED ( \ >> + RICHACE_WRITE_ATTRIBUTES | \ >> + RICHACE_WRITE_OWNER | \ >> + RICHACE_WRITE_ACL) >> + >> #endif /* __UAPI_RICHACL_H */ > > Other than the confusing comment, this looks ok. > > Reviewed-by: Jeff Layton Thanks, Andreas