From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andreas Gruenbacher Subject: [RFC v7 07/41] richacl: Permission mapping functions Date: Sat, 5 Sep 2015 12:27:02 +0200 Message-ID: <1441448856-13478-8-git-send-email-agruenba@redhat.com> References: <1441448856-13478-1-git-send-email-agruenba@redhat.com> To: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-api@vger.kernel.org, linux-cifs@vger.kernel.org, linux-security-module@vger.kernel.org Return-path: Received: from mx1.redhat.com ([209.132.183.28]:48472 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750960AbbIEK1w (ORCPT ); Sat, 5 Sep 2015 06:27:52 -0400 In-Reply-To: <1441448856-13478-1-git-send-email-agruenba@redhat.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: 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_base.c | 117 ++++++++++++++++++++++++++++++++++++++++++++++++ include/linux/richacl.h | 47 ++++++++++++++++++- 2 files changed, 163 insertions(+), 1 deletion(-) diff --git a/fs/richacl_base.c b/fs/richacl_base.c index 6d9a073..063dbe4 100644 --- a/fs/richacl_base.c +++ b/fs/richacl_base.c @@ -65,3 +65,120 @@ 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 + * + * 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(mode_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. + */ +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 bfa94bb..9c8f298 100644 --- a/include/linux/richacl.h +++ b/include/linux/richacl.h @@ -126,6 +126,49 @@ struct richacl { RICHACE_WRITE_OWNER | \ RICHACE_SYNCHRONIZE) +/* + * The POSIX permissions are supersets of the following NFSv4 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 NFSv4 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) /** * richacl_get - grab another reference to a richacl handle */ @@ -251,6 +294,8 @@ 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(mode_t); +extern unsigned int richacl_want_to_mask(unsigned int); #endif /* __RICHACL_H */ -- 2.4.3