| Message ID | b9fe1ea3ac5acdb5d2672d1522ff746f42c831be.1429868795.git.agruenba@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Looks OK. On Fri, Apr 24, 2015 at 01:04:23PM +0200, Andreas Gruenbacher wrote: > The POSIX standard puts processes which are not the owner or a member in > the owning group or which match any ace other then everyone@ on the > other file class. We only know if a process is in the other class after > processing the entire acl. > > Move all everyone@ aces in the acl down in the acl so that at most a > single everyone@ allow ace remains at the end. Permissions which are > not explicitly allowed are implicitly denied, so everyone@ deny ace is > needed. Should be "an everyone@ deny ace is unneeded". > The everyone@ aces can be moved down the acl without changing the > permissions that the acl grants. This transformation simplifies the > following algorithms, and eventually allows us to turn the final > everyone@ allow ace into an entry for the other class. > > Signed-off-by: Andreas Gruenbacher <agruen@kernel.org> > --- > fs/richacl_compat.c | 65 +++++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 65 insertions(+) > > diff --git a/fs/richacl_compat.c b/fs/richacl_compat.c > index 2ea6658..63f4373 100644 > --- a/fs/richacl_compat.c > +++ b/fs/richacl_compat.c > @@ -159,3 +159,68 @@ richace_change_mask(struct richacl_alloc *x, struct richace **ace, > } > return 0; > } > + > +/** > + * richacl_move_everyone_aces_down - move everyone@ aces to the end of the acl > + * @x: acl and number of allocated entries > + * > + * Move all everyone aces to the end of the acl so that only a single everyone@ > + * allow ace remains at the end, and update the mask fields of all aces on the > + * way. The last ace of the resulting acl will be an everyone@ allow ace only > + * if @acl grants any permissions to @everyone. No @everyone deny aces will > + * remain. > + * > + * This transformation does not alter the permissions that the acl grants. > + * Having at most one everyone@ allow ace at the end of the acl helps us in the > + * following algorithms. May be worth documenting the return convention (0 == success, -1 == out of memory?), though I guess it's the same for everything here. Looks fine otherwise. --b. > + */ > +static int > +richacl_move_everyone_aces_down(struct richacl_alloc *x) > +{ > + struct richace *ace; > + unsigned int allowed = 0, denied = 0; > + > + richacl_for_each_entry(ace, x->acl) { > + if (richace_is_inherit_only(ace)) > + continue; > + if (richace_is_everyone(ace)) { > + if (richace_is_allow(ace)) > + allowed |= (ace->e_mask & ~denied); > + else if (richace_is_deny(ace)) > + denied |= (ace->e_mask & ~allowed); > + else > + continue; > + if (richace_change_mask(x, &ace, 0)) > + return -1; > + } else { > + if (richace_is_allow(ace)) { > + if (richace_change_mask(x, &ace, allowed | > + (ace->e_mask & ~denied))) > + return -1; > + } else if (richace_is_deny(ace)) { > + if (richace_change_mask(x, &ace, denied | > + (ace->e_mask & ~allowed))) > + return -1; > + } > + } > + } > + if (allowed & ~RICHACE_POSIX_ALWAYS_ALLOWED) { > + struct richace *last_ace = ace - 1; > + > + if (x->acl->a_entries && > + richace_is_everyone(last_ace) && > + richace_is_allow(last_ace) && > + richace_is_inherit_only(last_ace) && > + last_ace->e_mask == allowed) > + last_ace->e_flags &= ~RICHACE_INHERIT_ONLY_ACE; > + else { > + if (richacl_insert_entry(x, &ace)) > + return -1; > + ace->e_type = RICHACE_ACCESS_ALLOWED_ACE_TYPE; > + ace->e_flags = RICHACE_SPECIAL_WHO; > + ace->e_mask = allowed; > + ace->e_id.special = RICHACE_EVERYONE_SPECIAL_ID; > + } > + } > + return 0; > +} > -- > 2.1.0 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/richacl_compat.c b/fs/richacl_compat.c index 2ea6658..63f4373 100644 --- a/fs/richacl_compat.c +++ b/fs/richacl_compat.c @@ -159,3 +159,68 @@ richace_change_mask(struct richacl_alloc *x, struct richace **ace, } return 0; } + +/** + * richacl_move_everyone_aces_down - move everyone@ aces to the end of the acl + * @x: acl and number of allocated entries + * + * Move all everyone aces to the end of the acl so that only a single everyone@ + * allow ace remains at the end, and update the mask fields of all aces on the + * way. The last ace of the resulting acl will be an everyone@ allow ace only + * if @acl grants any permissions to @everyone. No @everyone deny aces will + * remain. + * + * This transformation does not alter the permissions that the acl grants. + * Having at most one everyone@ allow ace at the end of the acl helps us in the + * following algorithms. + */ +static int +richacl_move_everyone_aces_down(struct richacl_alloc *x) +{ + struct richace *ace; + unsigned int allowed = 0, denied = 0; + + richacl_for_each_entry(ace, x->acl) { + if (richace_is_inherit_only(ace)) + continue; + if (richace_is_everyone(ace)) { + if (richace_is_allow(ace)) + allowed |= (ace->e_mask & ~denied); + else if (richace_is_deny(ace)) + denied |= (ace->e_mask & ~allowed); + else + continue; + if (richace_change_mask(x, &ace, 0)) + return -1; + } else { + if (richace_is_allow(ace)) { + if (richace_change_mask(x, &ace, allowed | + (ace->e_mask & ~denied))) + return -1; + } else if (richace_is_deny(ace)) { + if (richace_change_mask(x, &ace, denied | + (ace->e_mask & ~allowed))) + return -1; + } + } + } + if (allowed & ~RICHACE_POSIX_ALWAYS_ALLOWED) { + struct richace *last_ace = ace - 1; + + if (x->acl->a_entries && + richace_is_everyone(last_ace) && + richace_is_allow(last_ace) && + richace_is_inherit_only(last_ace) && + last_ace->e_mask == allowed) + last_ace->e_flags &= ~RICHACE_INHERIT_ONLY_ACE; + else { + if (richacl_insert_entry(x, &ace)) + return -1; + ace->e_type = RICHACE_ACCESS_ALLOWED_ACE_TYPE; + ace->e_flags = RICHACE_SPECIAL_WHO; + ace->e_mask = allowed; + ace->e_id.special = RICHACE_EVERYONE_SPECIAL_ID; + } + } + return 0; +}
The POSIX standard puts processes which are not the owner or a member in the owning group or which match any ace other then everyone@ on the other file class. We only know if a process is in the other class after processing the entire acl. Move all everyone@ aces in the acl down in the acl so that at most a single everyone@ allow ace remains at the end. Permissions which are not explicitly allowed are implicitly denied, so everyone@ deny ace is needed. The everyone@ aces can be moved down the acl without changing the permissions that the acl grants. This transformation simplifies the following algorithms, and eventually allows us to turn the final everyone@ allow ace into an entry for the other class. Signed-off-by: Andreas Gruenbacher <agruen@kernel.org> --- fs/richacl_compat.c | 65 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 65 insertions(+)