So far, richacl_equiv_mode() is relatively limited in the types of acl it considers equivalent to a file mode: it only accepts masked acls with a single everyone@:rwpxd::allow entry.
Change this to consider all acls equivalent to file modes if they only consist of owner@, group@, and everyone@ entries and the owner@ permissions do not depend on whether the owner is a member in the owning group. Signed-off-by: Andreas Gruenbacher <[email protected]> --- fs/richacl_base.c | 150 ++++++++++++++++++++++++++++++++++++++---------- include/linux/richacl.h | 1 + 2 files changed, 122 insertions(+), 29 deletions(-) diff --git a/fs/richacl_base.c b/fs/richacl_base.c index db27542..54cb482 100644 --- a/fs/richacl_base.c +++ b/fs/richacl_base.c @@ -439,49 +439,141 @@ richacl_inherit(const struct richacl *dir_acl, int isdir) } /** - * richacl_equiv_mode - check if @acl is equivalent to file permission bits - * @mode_p: the file mode (including the file type) + * __richacl_equiv_mode - compute the mode equivalent of @acl * - * If @acl can be fully represented by file permission bits, this function - * returns 0, and the file permission bits in @mode_p are set to the equivalent - * of @acl. + * This function does not consider the masks in @acl. * - * This function is used to avoid storing richacls on disk if the acl can be - * computed from the file permission bits. It allows user-space to make sure - * that a file has no explicit richacl set. + * An acl is considered equivalent to a file mode if it only consists of + * owner@, group@, and everyone@ entries and the owner@ permissions do not + * depend on whether the owner is a member in the owning group. */ int -richacl_equiv_mode(const struct richacl *acl, mode_t *mode_p) +__richacl_equiv_mode(const struct richacl *acl, mode_t *mode_p) { - const struct richace *ace = acl->a_entries; - unsigned int x; - mode_t mask; - - if (acl->a_count != 1 || - acl->a_flags != RICHACL_MASKED || - !richace_is_everyone(ace) || - !richace_is_allow(ace) || - ace->e_flags & ~RICHACE_SPECIAL_WHO) + mode_t mode = *mode_p; + + /* + * The RICHACE_DELETE_CHILD flag is meaningless for non-directories, so + * we ignore it. + */ + unsigned int x = S_ISDIR(mode) ? 0 : RICHACE_DELETE_CHILD; + struct { + unsigned int allowed; + unsigned int defined; /* allowed or denied */ + } owner = { + .allowed = RICHACE_POSIX_ALWAYS_ALLOWED, + .defined = RICHACE_POSIX_ALWAYS_ALLOWED | RICHACE_POSIX_OWNER_ALLOWED | x, + }, group = { + .allowed = RICHACE_POSIX_ALWAYS_ALLOWED, + .defined = RICHACE_POSIX_ALWAYS_ALLOWED | x, + }, everyone = { + .allowed = RICHACE_POSIX_ALWAYS_ALLOWED, + .defined = RICHACE_POSIX_ALWAYS_ALLOWED | x, + }; + const struct richace *ace; + + richacl_for_each_entry(ace, acl) { + if (ace->e_flags & ~RICHACE_SPECIAL_WHO) + return -1; + + if (richace_is_owner(ace) || richace_is_everyone(ace)) { + x = ace->e_mask & ~owner.defined; + if (richace_is_allow(ace)) { + unsigned int group_denied = group.defined & ~group.allowed; + + if (x & group_denied) + return -1; + owner.allowed |= x; + } else /* if (richace_is_deny(ace)) */ { + if (x & group.allowed) + return -1; + } + owner.defined |= x; + + if (richace_is_everyone(ace)) { + x = ace->e_mask; + if (richace_is_allow(ace)) { + group.allowed |= x & ~group.defined; + everyone.allowed |= x & ~everyone.defined; + } + group.defined |= x; + everyone.defined |= x; + } + } else if (richace_is_group(ace)) { + x = ace->e_mask & ~group.defined; + if (richace_is_allow(ace)) + group.allowed |= x; + group.defined |= x; + } else + return -1; + } + + if (group.allowed & ~owner.defined) return -1; - /* Mask flags we can ignore */ - x = ~RICHACE_POSIX_ALWAYS_ALLOWED; - if (!S_ISDIR(*mode_p)) - x &= ~RICHACE_DELETE_CHILD; + if (acl->a_flags & RICHACL_MASKED) { + owner.allowed &= acl->a_owner_mask; + group.allowed &= acl->a_group_mask; + everyone.allowed &= acl->a_other_mask; + } - mask = richacl_masks_to_mode(acl); - if (((acl->a_group_mask ^ richacl_mode_to_mask(mask >> 3)) & x) || - ((acl->a_other_mask ^ richacl_mode_to_mask(mask)) & x)) + mode = (mode & ~S_IRWXUGO) | + (richacl_mask_to_mode(owner.allowed) << 6) | + (richacl_mask_to_mode(group.allowed) << 3) | + richacl_mask_to_mode(everyone.allowed); + + /* Mask flags we can ignore */ + x = ~(S_ISDIR(mode) ? 0 : RICHACE_DELETE_CHILD); + if (((richacl_mode_to_mask(mode >> 6) ^ owner.allowed) & x) || + ((richacl_mode_to_mask(mode >> 3) ^ group.allowed) & x) || + ((richacl_mode_to_mask(mode) ^ everyone.allowed) & x)) return -1; - x &= ~RICHACE_POSIX_OWNER_ALLOWED; - if ((acl->a_owner_mask ^ richacl_mode_to_mask(mask >> 6)) & x) + *mode_p = mode; + return 0; +} +EXPORT_SYMBOL_GPL(__richacl_equiv_mode); + +/** + * richacl_equiv_mode - determine if @acl is equivalent to a file mode + * @mode_p: the file mode + * + * The file type in @mode_p must be set when calling richacl_equiv_mode(). + * + * Returns with 0 if @acl is equivalent to a file mode; in that case, the + * file permission bits in @mode_p are set to the mode equivalent of @acl. + */ +int +richacl_equiv_mode(const struct richacl *acl, mode_t *mode_p) +{ + mode_t mode = *mode_p; + + if (acl->a_flags & ~RICHACL_MASKED) return -1; - if ((ace->e_mask ^ RICHACE_POSIX_MODE_ALL) & x) + if (__richacl_equiv_mode(acl, &mode)) return -1; - *mode_p = (*mode_p & ~S_IRWXUGO) | mask; + if (acl->a_flags & RICHACL_MASKED) { + mode_t mask = richacl_masks_to_mode(acl); + unsigned int x; + + /* Mask flags we can ignore */ + x = ~(RICHACE_POSIX_ALWAYS_ALLOWED | + (S_ISDIR(mode) ? 0 : RICHACE_DELETE_CHILD)); + + if (((acl->a_group_mask ^ richacl_mode_to_mask(mask >> 3)) & x) || + ((acl->a_other_mask ^ richacl_mode_to_mask(mask)) & x)) + return -1; + + x &= ~RICHACE_POSIX_OWNER_ALLOWED; + if ((acl->a_owner_mask ^ richacl_mode_to_mask(mask >> 6)) & x) + return -1; + + mode &= ~S_IRWXUGO | mask; + } + + *mode_p = mode; return 0; } EXPORT_SYMBOL_GPL(richacl_equiv_mode); diff --git a/include/linux/richacl.h b/include/linux/richacl.h index c6fd0a1..8a92b89 100644 --- a/include/linux/richacl.h +++ b/include/linux/richacl.h @@ -297,6 +297,7 @@ extern unsigned int richacl_want_to_mask(unsigned int); extern void richacl_compute_max_masks(struct richacl *); extern struct richacl *richacl_chmod(struct richacl *, mode_t); extern struct richacl *richacl_inherit(const struct richacl *, int); +extern int __richacl_equiv_mode(const struct richacl *, mode_t *); extern int richacl_equiv_mode(const struct richacl *, mode_t *); /* richacl_inode.c */ -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
