| Message ID | 20190828204259.23160-1-joshua.brindle@crunchydata.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v2] default_range glblub implementation | expand |
On Wed, Aug 28, 2019 at 4:43 PM Joshua Brindle <joshua.brindle@crunchydata.com> wrote: > > A policy developer can now specify glblub as a default_range default and > the computed transition will be the intersection of the mls range of > the two contexts. > > The glb (greatest lower bound) lub (lowest upper bound) of a range is calculated > as the greater of the low sensitivities and the lower of the high sensitivities > and the and of each category bitmap. > > This can be used by MLS solution developers to compute a context that satisfies, > for example, the range of a network interface and the range of a user logging in. > > Some examples are: > > User Permitted Range | Network Device Label | Computed Label > ---------------------|----------------------|---------------- > S0-S1:c0.c12 | S0 | S0 > S0-S1:c0.c12 | S0-S1:c0.c1024 | S0-S1:c0.c12 > S0-S4:c0.c512 | S1-S1:c0.c1024 | S1-S1:c0.c512 > S0-S16:c0,c2 | S4-S6:c0.c128 | S4-S6:c0,c2 > S0-S4 | S2-S6 | S2-S4 > S0-S4 | S5-S8 | INVALID > S5-S8 | S0-S4 | INVALID > S6:c0,c2-S7:c4,c5 | S0:c2,c4-S6:c5.c100 | S6:c2-S6:c5 > > Signed-off-by: Joshua Brindle <joshua.brindle@crunchydata.com> > --- > security/selinux/include/security.h | 3 ++- > security/selinux/ss/context.h | 28 ++++++++++++++++++++++++++++ > security/selinux/ss/ebitmap.c | 18 ++++++++++++++++++ > security/selinux/ss/ebitmap.h | 1 + > security/selinux/ss/mls.c | 2 ++ > security/selinux/ss/policydb.c | 5 +++++ > security/selinux/ss/policydb.h | 1 + > 7 files changed, 57 insertions(+), 1 deletion(-) You incorporated some feedback from the v1 patch, but you ignored some, can you explain why? For reference, here are my comments on your first patch: * https://lore.kernel.org/selinux/CAHC9VhRXyRDjj3KJDHvA4ruJg6H+1kzFPzfA-PLZ-NqBicsLrw@mail.gmail.com/
On Wed, Aug 28, 2019 at 6:31 PM Paul Moore <paul@paul-moore.com> wrote: > > On Wed, Aug 28, 2019 at 4:43 PM Joshua Brindle > <joshua.brindle@crunchydata.com> wrote: > > > > A policy developer can now specify glblub as a default_range default and > > the computed transition will be the intersection of the mls range of > > the two contexts. > > > > The glb (greatest lower bound) lub (lowest upper bound) of a range is calculated > > as the greater of the low sensitivities and the lower of the high sensitivities > > and the and of each category bitmap. > > > > This can be used by MLS solution developers to compute a context that satisfies, > > for example, the range of a network interface and the range of a user logging in. > > > > Some examples are: > > > > User Permitted Range | Network Device Label | Computed Label > > ---------------------|----------------------|---------------- > > S0-S1:c0.c12 | S0 | S0 > > S0-S1:c0.c12 | S0-S1:c0.c1024 | S0-S1:c0.c12 > > S0-S4:c0.c512 | S1-S1:c0.c1024 | S1-S1:c0.c512 > > S0-S16:c0,c2 | S4-S6:c0.c128 | S4-S6:c0,c2 > > S0-S4 | S2-S6 | S2-S4 > > S0-S4 | S5-S8 | INVALID > > S5-S8 | S0-S4 | INVALID > > S6:c0,c2-S7:c4,c5 | S0:c2,c4-S6:c5.c100 | S6:c2-S6:c5 > > > > Signed-off-by: Joshua Brindle <joshua.brindle@crunchydata.com> > > --- > > security/selinux/include/security.h | 3 ++- > > security/selinux/ss/context.h | 28 ++++++++++++++++++++++++++++ > > security/selinux/ss/ebitmap.c | 18 ++++++++++++++++++ > > security/selinux/ss/ebitmap.h | 1 + > > security/selinux/ss/mls.c | 2 ++ > > security/selinux/ss/policydb.c | 5 +++++ > > security/selinux/ss/policydb.h | 1 + > > 7 files changed, 57 insertions(+), 1 deletion(-) > > You incorporated some feedback from the v1 patch, but you ignored > some, can you explain why? > I apologize, I missed a couple C++ style comments, I'll fix those and resend, was there anything else? I thought I addressed all of the technical concerns. > For reference, here are my comments on your first patch: > * https://lore.kernel.org/selinux/CAHC9VhRXyRDjj3KJDHvA4ruJg6H+1kzFPzfA-PLZ-NqBicsLrw@mail.gmail.com/ > > -- > paul moore > www.paul-moore.com
On Thu, Aug 29, 2019 at 9:29 AM Joshua Brindle <joshua.brindle@crunchydata.com> wrote: > On Wed, Aug 28, 2019 at 6:31 PM Paul Moore <paul@paul-moore.com> wrote: > > On Wed, Aug 28, 2019 at 4:43 PM Joshua Brindle > > <joshua.brindle@crunchydata.com> wrote: > > > > > > A policy developer can now specify glblub as a default_range default and > > > the computed transition will be the intersection of the mls range of > > > the two contexts. > > > > > > The glb (greatest lower bound) lub (lowest upper bound) of a range is calculated > > > as the greater of the low sensitivities and the lower of the high sensitivities > > > and the and of each category bitmap. > > > > > > This can be used by MLS solution developers to compute a context that satisfies, > > > for example, the range of a network interface and the range of a user logging in. > > > > > > Some examples are: > > > > > > User Permitted Range | Network Device Label | Computed Label > > > ---------------------|----------------------|---------------- > > > S0-S1:c0.c12 | S0 | S0 > > > S0-S1:c0.c12 | S0-S1:c0.c1024 | S0-S1:c0.c12 > > > S0-S4:c0.c512 | S1-S1:c0.c1024 | S1-S1:c0.c512 > > > S0-S16:c0,c2 | S4-S6:c0.c128 | S4-S6:c0,c2 > > > S0-S4 | S2-S6 | S2-S4 > > > S0-S4 | S5-S8 | INVALID > > > S5-S8 | S0-S4 | INVALID > > > S6:c0,c2-S7:c4,c5 | S0:c2,c4-S6:c5.c100 | S6:c2-S6:c5 > > > > > > Signed-off-by: Joshua Brindle <joshua.brindle@crunchydata.com> > > > --- > > > security/selinux/include/security.h | 3 ++- > > > security/selinux/ss/context.h | 28 ++++++++++++++++++++++++++++ > > > security/selinux/ss/ebitmap.c | 18 ++++++++++++++++++ > > > security/selinux/ss/ebitmap.h | 1 + > > > security/selinux/ss/mls.c | 2 ++ > > > security/selinux/ss/policydb.c | 5 +++++ > > > security/selinux/ss/policydb.h | 1 + > > > 7 files changed, 57 insertions(+), 1 deletion(-) > > > > You incorporated some feedback from the v1 patch, but you ignored > > some, can you explain why? > > > > I apologize, I missed a couple C++ style comments, I'll fix those and > resend, was there anything else? I thought I addressed all of the > technical concerns. My biggest concern wasn't really the style nits (although please do fix those), but rather the guts of ebitmap_and() and the use of ebitmap_get_bit() instead of something a bit more efficient. Here is my original comment: "Beyond that, since this is an AND operation, could we make better use of things like find_first_bit()/ebitmap_start_positive()/ ebitmap_next_positive() to skip along one of the bitmaps instead of needing to call ebitmap_get_bit() for each bit? I imagine it would be quicker that way." > > For reference, here are my comments on your first patch: > > * https://lore.kernel.org/selinux/CAHC9VhRXyRDjj3KJDHvA4ruJg6H+1kzFPzfA-PLZ-NqBicsLrw@mail.gmail.com/
On Thu, Aug 29, 2019 at 12:59 PM Paul Moore <paul@paul-moore.com> wrote: > > On Thu, Aug 29, 2019 at 9:29 AM Joshua Brindle > <joshua.brindle@crunchydata.com> wrote: > > On Wed, Aug 28, 2019 at 6:31 PM Paul Moore <paul@paul-moore.com> wrote: > > > On Wed, Aug 28, 2019 at 4:43 PM Joshua Brindle > > > <joshua.brindle@crunchydata.com> wrote: > > > > > > > > A policy developer can now specify glblub as a default_range default and > > > > the computed transition will be the intersection of the mls range of > > > > the two contexts. > > > > > > > > The glb (greatest lower bound) lub (lowest upper bound) of a range is calculated > > > > as the greater of the low sensitivities and the lower of the high sensitivities > > > > and the and of each category bitmap. > > > > > > > > This can be used by MLS solution developers to compute a context that satisfies, > > > > for example, the range of a network interface and the range of a user logging in. > > > > > > > > Some examples are: > > > > > > > > User Permitted Range | Network Device Label | Computed Label > > > > ---------------------|----------------------|---------------- > > > > S0-S1:c0.c12 | S0 | S0 > > > > S0-S1:c0.c12 | S0-S1:c0.c1024 | S0-S1:c0.c12 > > > > S0-S4:c0.c512 | S1-S1:c0.c1024 | S1-S1:c0.c512 > > > > S0-S16:c0,c2 | S4-S6:c0.c128 | S4-S6:c0,c2 > > > > S0-S4 | S2-S6 | S2-S4 > > > > S0-S4 | S5-S8 | INVALID > > > > S5-S8 | S0-S4 | INVALID > > > > S6:c0,c2-S7:c4,c5 | S0:c2,c4-S6:c5.c100 | S6:c2-S6:c5 > > > > > > > > Signed-off-by: Joshua Brindle <joshua.brindle@crunchydata.com> > > > > --- > > > > security/selinux/include/security.h | 3 ++- > > > > security/selinux/ss/context.h | 28 ++++++++++++++++++++++++++++ > > > > security/selinux/ss/ebitmap.c | 18 ++++++++++++++++++ > > > > security/selinux/ss/ebitmap.h | 1 + > > > > security/selinux/ss/mls.c | 2 ++ > > > > security/selinux/ss/policydb.c | 5 +++++ > > > > security/selinux/ss/policydb.h | 1 + > > > > 7 files changed, 57 insertions(+), 1 deletion(-) > > > > > > You incorporated some feedback from the v1 patch, but you ignored > > > some, can you explain why? > > > > > > > I apologize, I missed a couple C++ style comments, I'll fix those and > > resend, was there anything else? I thought I addressed all of the > > technical concerns. > > My biggest concern wasn't really the style nits (although please do > fix those), but rather the guts of ebitmap_and() and the use of > ebitmap_get_bit() instead of something a bit more efficient. Here is > my original comment: > > "Beyond that, since this is an AND operation, could we make better > use of things like find_first_bit()/ebitmap_start_positive()/ > ebitmap_next_positive() to skip along one of the bitmaps instead > of needing to call ebitmap_get_bit() for each bit? I imagine it > would be quicker that way." > I used ebitmap_for_each_positive_bit() for the outer loop which uses ebitmap_start_positive() and ebitmap_next_positive(). I suppose I could try to track both lists at the same time and AND the bitmaps when the startbit is the same but I don't expect this to really be any kind of bottleneck. > > > For reference, here are my comments on your first patch: > > > * https://lore.kernel.org/selinux/CAHC9VhRXyRDjj3KJDHvA4ruJg6H+1kzFPzfA-PLZ-NqBicsLrw@mail.gmail.com/ > > -- > paul moore > www.paul-moore.com
On 8/28/19 4:43 PM, Joshua Brindle wrote: > A policy developer can now specify glblub as a default_range default and > the computed transition will be the intersection of the mls range of > the two contexts. > > The glb (greatest lower bound) lub (lowest upper bound) of a range is calculated > as the greater of the low sensitivities and the lower of the high sensitivities > and the and of each category bitmap. > > This can be used by MLS solution developers to compute a context that satisfies, > for example, the range of a network interface and the range of a user logging in. > > Some examples are: > > User Permitted Range | Network Device Label | Computed Label > ---------------------|----------------------|---------------- > S0-S1:c0.c12 | S0 | S0 > S0-S1:c0.c12 | S0-S1:c0.c1024 | S0-S1:c0.c12 > S0-S4:c0.c512 | S1-S1:c0.c1024 | S1-S1:c0.c512 > S0-S16:c0,c2 | S4-S6:c0.c128 | S4-S6:c0,c2 > S0-S4 | S2-S6 | S2-S4 > S0-S4 | S5-S8 | INVALID > S5-S8 | S0-S4 | INVALID > S6:c0,c2-S7:c4,c5 | S0:c2,c4-S6:c5.c100 | S6:c2-S6:c5 I don't quite understand why it is an AND / intersection of the categories on both levels. Normally lub would be an OR / union. Possibly it is just a terminology issue. Is this "glblub" relation defined by anyone else, or used in any other MLS system? Also, I'm left wondering whether certain cases of differing category sets ought to yield an INVALID state. What if the user's permitted range was s0:c0,c5-s15:c0,c5 and the network device label was s0:c13? Or take your last example - is it really correct to let the user login w/o c0? > > Signed-off-by: Joshua Brindle <joshua.brindle@crunchydata.com> > --- > security/selinux/include/security.h | 3 ++- > security/selinux/ss/context.h | 28 ++++++++++++++++++++++++++++ > security/selinux/ss/ebitmap.c | 18 ++++++++++++++++++ > security/selinux/ss/ebitmap.h | 1 + > security/selinux/ss/mls.c | 2 ++ > security/selinux/ss/policydb.c | 5 +++++ > security/selinux/ss/policydb.h | 1 + > 7 files changed, 57 insertions(+), 1 deletion(-) > > diff --git a/security/selinux/include/security.h b/security/selinux/include/security.h > index 111121281c47..ae840634e3c7 100644 > --- a/security/selinux/include/security.h > +++ b/security/selinux/include/security.h > @@ -40,10 +40,11 @@ > #define POLICYDB_VERSION_CONSTRAINT_NAMES 29 > #define POLICYDB_VERSION_XPERMS_IOCTL 30 > #define POLICYDB_VERSION_INFINIBAND 31 > +#define POLICYDB_VERSION_GLBLUB 32 > > /* Range of policy versions we understand*/ > #define POLICYDB_VERSION_MIN POLICYDB_VERSION_BASE > -#define POLICYDB_VERSION_MAX POLICYDB_VERSION_INFINIBAND > +#define POLICYDB_VERSION_MAX POLICYDB_VERSION_GLBLUB > > /* Mask for just the mount related flags */ > #define SE_MNTMASK 0x0f > diff --git a/security/selinux/ss/context.h b/security/selinux/ss/context.h > index 2260c44a568c..0a0fbcc0d90c 100644 > --- a/security/selinux/ss/context.h > +++ b/security/selinux/ss/context.h > @@ -95,6 +95,34 @@ static inline int mls_context_cpy_high(struct context *dst, struct context *src) > return rc; > } > > + > +static inline int mls_context_glblub(struct context *dst, struct context *c1, struct context *c2) > +{ > + struct mls_range *dr = &dst->range, *r1 = &c1->range, *r2 = &c2->range; > + int rc = 0; > + > + if (r1->level[1].sens < r2->level[0].sens || r2->level[1].sens < r1->level[0].sens) > + /* These ranges have no common sensitivities */ > + return -1; This error will get propagate to userspace as an errno? So it should be -EINVAL? > + > + // Take the greatest of the low > + dr->level[0].sens = max(r1->level[0].sens, r2->level[0].sens); > + > + // Take the least of the high > + dr->level[1].sens = min(r1->level[1].sens, r2->level[1].sens); > + > + rc = ebitmap_and(&dr->level[0].cat, &r1->level[0].cat, &r2->level[0].cat); > + if (rc) > + goto out; > + > + rc = ebitmap_and(&dr->level[1].cat, &r1->level[1].cat, &r2->level[1].cat); > + if (rc) > + goto out; > + > +out: > + return rc; > +} > + > static inline int mls_context_cmp(struct context *c1, struct context *c2) > { > return ((c1->range.level[0].sens == c2->range.level[0].sens) && > diff --git a/security/selinux/ss/ebitmap.c b/security/selinux/ss/ebitmap.c > index 09929fc5ab47..c0a9f8ecffc3 100644 > --- a/security/selinux/ss/ebitmap.c > +++ b/security/selinux/ss/ebitmap.c > @@ -77,6 +77,24 @@ int ebitmap_cpy(struct ebitmap *dst, struct ebitmap *src) > return 0; > } > > +int ebitmap_and(struct ebitmap *dst, struct ebitmap *e1, struct ebitmap *e2) > +{ > + struct ebitmap_node *n; > + int bit; > + > + ebitmap_init(dst); > + > + ebitmap_for_each_positive_bit(e1, n, bit) { > + if (ebitmap_get_bit(e2, bit)) { > + int rc = ebitmap_set_bit(dst, bit, 1); > + if (rc < 0) > + return rc; > + } > + } > + return 0; > +} > + > + > #ifdef CONFIG_NETLABEL > /** > * ebitmap_netlbl_export - Export an ebitmap into a NetLabel category bitmap > diff --git a/security/selinux/ss/ebitmap.h b/security/selinux/ss/ebitmap.h > index 6aa7cf6a2197..9a23b81b8832 100644 > --- a/security/selinux/ss/ebitmap.h > +++ b/security/selinux/ss/ebitmap.h > @@ -124,6 +124,7 @@ static inline void ebitmap_node_clr_bit(struct ebitmap_node *n, > > int ebitmap_cmp(struct ebitmap *e1, struct ebitmap *e2); > int ebitmap_cpy(struct ebitmap *dst, struct ebitmap *src); > +int ebitmap_and(struct ebitmap *dst, struct ebitmap *e1, struct ebitmap *e2); > int ebitmap_contains(struct ebitmap *e1, struct ebitmap *e2, u32 last_e2bit); > int ebitmap_get_bit(struct ebitmap *e, unsigned long bit); > int ebitmap_set_bit(struct ebitmap *e, unsigned long bit, int value); > diff --git a/security/selinux/ss/mls.c b/security/selinux/ss/mls.c > index 5e05f5b902d7..76c8ad014ac9 100644 > --- a/security/selinux/ss/mls.c > +++ b/security/selinux/ss/mls.c > @@ -529,6 +529,8 @@ int mls_compute_sid(struct policydb *p, > return mls_context_cpy_high(newcontext, tcontext); > case DEFAULT_TARGET_LOW_HIGH: > return mls_context_cpy(newcontext, tcontext); > + case DEFAULT_GLBLUB: > + return mls_context_glblub(newcontext, scontext, tcontext); > } > > /* Fallthrough */ > diff --git a/security/selinux/ss/policydb.c b/security/selinux/ss/policydb.c > index f8efaa9f647c..1b59f72effbb 100644 > --- a/security/selinux/ss/policydb.c > +++ b/security/selinux/ss/policydb.c > @@ -160,6 +160,11 @@ static struct policydb_compat_info policydb_compat[] = { > .sym_num = SYM_NUM, > .ocon_num = OCON_NUM, > }, > + { > + .version = POLICYDB_VERSION_GLBLUB, > + .sym_num = SYM_NUM, > + .ocon_num = OCON_NUM, > + }, > }; > > static struct policydb_compat_info *policydb_lookup_compat(int version) > diff --git a/security/selinux/ss/policydb.h b/security/selinux/ss/policydb.h > index fcc6366b447f..0c41d0b4da96 100644 > --- a/security/selinux/ss/policydb.h > +++ b/security/selinux/ss/policydb.h > @@ -69,6 +69,7 @@ struct class_datum { > #define DEFAULT_TARGET_LOW 4 > #define DEFAULT_TARGET_HIGH 5 > #define DEFAULT_TARGET_LOW_HIGH 6 > +#define DEFAULT_GLBLUB 7 > char default_range; > }; > >
On Thu, Aug 29, 2019 at 4:46 PM Stephen Smalley <sds@tycho.nsa.gov> wrote: > > On 8/28/19 4:43 PM, Joshua Brindle wrote: > > A policy developer can now specify glblub as a default_range default and > > the computed transition will be the intersection of the mls range of > > the two contexts. > > > > The glb (greatest lower bound) lub (lowest upper bound) of a range is calculated > > as the greater of the low sensitivities and the lower of the high sensitivities > > and the and of each category bitmap. > > > > This can be used by MLS solution developers to compute a context that satisfies, > > for example, the range of a network interface and the range of a user logging in. > > > > Some examples are: > > > > User Permitted Range | Network Device Label | Computed Label > > ---------------------|----------------------|---------------- > > S0-S1:c0.c12 | S0 | S0 > > S0-S1:c0.c12 | S0-S1:c0.c1024 | S0-S1:c0.c12 > > S0-S4:c0.c512 | S1-S1:c0.c1024 | S1-S1:c0.c512 > > S0-S16:c0,c2 | S4-S6:c0.c128 | S4-S6:c0,c2 > > S0-S4 | S2-S6 | S2-S4 > > S0-S4 | S5-S8 | INVALID > > S5-S8 | S0-S4 | INVALID > > S6:c0,c2-S7:c4,c5 | S0:c2,c4-S6:c5.c100 | S6:c2-S6:c5 > > I don't quite understand why it is an AND / intersection of the > categories on both levels. Normally lub would be an OR / union. > Possibly it is just a terminology issue. Is this "glblub" relation > defined by anyone else, or used in any other MLS system? I talked to the other MLS people about it during LSS. I may be conflating things by combining the GLB and LUB into a single transition but conceptually I think it is what we need. The network interface range will always be what clearance and categories that network is approved for, the user has their own set of clearances and categories assigned to them. The idea is that you can only access something that both the user has clearance to see and the network is approved for. > > Also, I'm left wondering whether certain cases of differing category > sets ought to yield an INVALID state. What if the user's permitted > range was s0:c0,c5-s15:c0,c5 and the network device label was s0:c13? Or > take your last example - is it really correct to let the user login w/o c0? > In this example the user may be read into the c0 and c5 programs, but the network is only authorized for the c13 program. This would degenerate into only s0 information is available, which I believe is correct since the user isn't read into c13 and the network is only approved for that. BTW this gets even more complicated for inverse bits, the network would be connected to/approved for coalition partner A so that bit is turned off in the inverse bit section so a US person logging in over that network could only see data releasable to coalition partner A, even though they are US, which also seems correct since otherwise there would be potential to leak non-releasable info. Another MLS person encouraged me to do this in userspace because the kernel wouldn't know what a "valid" range is for a deployed system. While mcstransd does some bit math on the ranges to me the kernel owns this information. The resulting label can be passed onto mcstransd and if it violates a constraint there we can deny the entire operation. > > > > Signed-off-by: Joshua Brindle <joshua.brindle@crunchydata.com> > > --- > > security/selinux/include/security.h | 3 ++- > > security/selinux/ss/context.h | 28 ++++++++++++++++++++++++++++ > > security/selinux/ss/ebitmap.c | 18 ++++++++++++++++++ > > security/selinux/ss/ebitmap.h | 1 + > > security/selinux/ss/mls.c | 2 ++ > > security/selinux/ss/policydb.c | 5 +++++ > > security/selinux/ss/policydb.h | 1 + > > 7 files changed, 57 insertions(+), 1 deletion(-) > > > > diff --git a/security/selinux/include/security.h b/security/selinux/include/security.h > > index 111121281c47..ae840634e3c7 100644 > > --- a/security/selinux/include/security.h > > +++ b/security/selinux/include/security.h > > @@ -40,10 +40,11 @@ > > #define POLICYDB_VERSION_CONSTRAINT_NAMES 29 > > #define POLICYDB_VERSION_XPERMS_IOCTL 30 > > #define POLICYDB_VERSION_INFINIBAND 31 > > +#define POLICYDB_VERSION_GLBLUB 32 > > > > /* Range of policy versions we understand*/ > > #define POLICYDB_VERSION_MIN POLICYDB_VERSION_BASE > > -#define POLICYDB_VERSION_MAX POLICYDB_VERSION_INFINIBAND > > +#define POLICYDB_VERSION_MAX POLICYDB_VERSION_GLBLUB > > > > /* Mask for just the mount related flags */ > > #define SE_MNTMASK 0x0f > > diff --git a/security/selinux/ss/context.h b/security/selinux/ss/context.h > > index 2260c44a568c..0a0fbcc0d90c 100644 > > --- a/security/selinux/ss/context.h > > +++ b/security/selinux/ss/context.h > > @@ -95,6 +95,34 @@ static inline int mls_context_cpy_high(struct context *dst, struct context *src) > > return rc; > > } > > > > + > > +static inline int mls_context_glblub(struct context *dst, struct context *c1, struct context *c2) > > +{ > > + struct mls_range *dr = &dst->range, *r1 = &c1->range, *r2 = &c2->range; > > + int rc = 0; > > + > > + if (r1->level[1].sens < r2->level[0].sens || r2->level[1].sens < r1->level[0].sens) > > + /* These ranges have no common sensitivities */ > > + return -1; > > This error will get propagate to userspace as an errno? So it should be > -EINVAL? > > > + > > + // Take the greatest of the low > > + dr->level[0].sens = max(r1->level[0].sens, r2->level[0].sens); > > + > > + // Take the least of the high > > + dr->level[1].sens = min(r1->level[1].sens, r2->level[1].sens); > > + > > + rc = ebitmap_and(&dr->level[0].cat, &r1->level[0].cat, &r2->level[0].cat); > > + if (rc) > > + goto out; > > + > > + rc = ebitmap_and(&dr->level[1].cat, &r1->level[1].cat, &r2->level[1].cat); > > + if (rc) > > + goto out; > > + > > +out: > > + return rc; > > +} > > + > > static inline int mls_context_cmp(struct context *c1, struct context *c2) > > { > > return ((c1->range.level[0].sens == c2->range.level[0].sens) && > > diff --git a/security/selinux/ss/ebitmap.c b/security/selinux/ss/ebitmap.c > > index 09929fc5ab47..c0a9f8ecffc3 100644 > > --- a/security/selinux/ss/ebitmap.c > > +++ b/security/selinux/ss/ebitmap.c > > @@ -77,6 +77,24 @@ int ebitmap_cpy(struct ebitmap *dst, struct ebitmap *src) > > return 0; > > } > > > > +int ebitmap_and(struct ebitmap *dst, struct ebitmap *e1, struct ebitmap *e2) > > +{ > > + struct ebitmap_node *n; > > + int bit; > > + > > + ebitmap_init(dst); > > + > > + ebitmap_for_each_positive_bit(e1, n, bit) { > > + if (ebitmap_get_bit(e2, bit)) { > > + int rc = ebitmap_set_bit(dst, bit, 1); > > + if (rc < 0) > > + return rc; > > + } > > + } > > + return 0; > > +} > > + > > + > > #ifdef CONFIG_NETLABEL > > /** > > * ebitmap_netlbl_export - Export an ebitmap into a NetLabel category bitmap > > diff --git a/security/selinux/ss/ebitmap.h b/security/selinux/ss/ebitmap.h > > index 6aa7cf6a2197..9a23b81b8832 100644 > > --- a/security/selinux/ss/ebitmap.h > > +++ b/security/selinux/ss/ebitmap.h > > @@ -124,6 +124,7 @@ static inline void ebitmap_node_clr_bit(struct ebitmap_node *n, > > > > int ebitmap_cmp(struct ebitmap *e1, struct ebitmap *e2); > > int ebitmap_cpy(struct ebitmap *dst, struct ebitmap *src); > > +int ebitmap_and(struct ebitmap *dst, struct ebitmap *e1, struct ebitmap *e2); > > int ebitmap_contains(struct ebitmap *e1, struct ebitmap *e2, u32 last_e2bit); > > int ebitmap_get_bit(struct ebitmap *e, unsigned long bit); > > int ebitmap_set_bit(struct ebitmap *e, unsigned long bit, int value); > > diff --git a/security/selinux/ss/mls.c b/security/selinux/ss/mls.c > > index 5e05f5b902d7..76c8ad014ac9 100644 > > --- a/security/selinux/ss/mls.c > > +++ b/security/selinux/ss/mls.c > > @@ -529,6 +529,8 @@ int mls_compute_sid(struct policydb *p, > > return mls_context_cpy_high(newcontext, tcontext); > > case DEFAULT_TARGET_LOW_HIGH: > > return mls_context_cpy(newcontext, tcontext); > > + case DEFAULT_GLBLUB: > > + return mls_context_glblub(newcontext, scontext, tcontext); > > } > > > > /* Fallthrough */ > > diff --git a/security/selinux/ss/policydb.c b/security/selinux/ss/policydb.c > > index f8efaa9f647c..1b59f72effbb 100644 > > --- a/security/selinux/ss/policydb.c > > +++ b/security/selinux/ss/policydb.c > > @@ -160,6 +160,11 @@ static struct policydb_compat_info policydb_compat[] = { > > .sym_num = SYM_NUM, > > .ocon_num = OCON_NUM, > > }, > > + { > > + .version = POLICYDB_VERSION_GLBLUB, > > + .sym_num = SYM_NUM, > > + .ocon_num = OCON_NUM, > > + }, > > }; > > > > static struct policydb_compat_info *policydb_lookup_compat(int version) > > diff --git a/security/selinux/ss/policydb.h b/security/selinux/ss/policydb.h > > index fcc6366b447f..0c41d0b4da96 100644 > > --- a/security/selinux/ss/policydb.h > > +++ b/security/selinux/ss/policydb.h > > @@ -69,6 +69,7 @@ struct class_datum { > > #define DEFAULT_TARGET_LOW 4 > > #define DEFAULT_TARGET_HIGH 5 > > #define DEFAULT_TARGET_LOW_HIGH 6 > > +#define DEFAULT_GLBLUB 7 > > char default_range; > > }; > > > > >
On Thu, Aug 29, 2019 at 1:11 PM Joshua Brindle <joshua.brindle@crunchydata.com> wrote: > On Thu, Aug 29, 2019 at 12:59 PM Paul Moore <paul@paul-moore.com> wrote: > > On Thu, Aug 29, 2019 at 9:29 AM Joshua Brindle > > <joshua.brindle@crunchydata.com> wrote: > > > On Wed, Aug 28, 2019 at 6:31 PM Paul Moore <paul@paul-moore.com> wrote: > > > > On Wed, Aug 28, 2019 at 4:43 PM Joshua Brindle > > > > <joshua.brindle@crunchydata.com> wrote: > > > > > > > > > > A policy developer can now specify glblub as a default_range default and > > > > > the computed transition will be the intersection of the mls range of > > > > > the two contexts. > > > > > > > > > > The glb (greatest lower bound) lub (lowest upper bound) of a range is calculated > > > > > as the greater of the low sensitivities and the lower of the high sensitivities > > > > > and the and of each category bitmap. > > > > > > > > > > This can be used by MLS solution developers to compute a context that satisfies, > > > > > for example, the range of a network interface and the range of a user logging in. > > > > > > > > > > Some examples are: > > > > > > > > > > User Permitted Range | Network Device Label | Computed Label > > > > > ---------------------|----------------------|---------------- > > > > > S0-S1:c0.c12 | S0 | S0 > > > > > S0-S1:c0.c12 | S0-S1:c0.c1024 | S0-S1:c0.c12 > > > > > S0-S4:c0.c512 | S1-S1:c0.c1024 | S1-S1:c0.c512 > > > > > S0-S16:c0,c2 | S4-S6:c0.c128 | S4-S6:c0,c2 > > > > > S0-S4 | S2-S6 | S2-S4 > > > > > S0-S4 | S5-S8 | INVALID > > > > > S5-S8 | S0-S4 | INVALID > > > > > S6:c0,c2-S7:c4,c5 | S0:c2,c4-S6:c5.c100 | S6:c2-S6:c5 > > > > > > > > > > Signed-off-by: Joshua Brindle <joshua.brindle@crunchydata.com> > > > > > --- > > > > > security/selinux/include/security.h | 3 ++- > > > > > security/selinux/ss/context.h | 28 ++++++++++++++++++++++++++++ > > > > > security/selinux/ss/ebitmap.c | 18 ++++++++++++++++++ > > > > > security/selinux/ss/ebitmap.h | 1 + > > > > > security/selinux/ss/mls.c | 2 ++ > > > > > security/selinux/ss/policydb.c | 5 +++++ > > > > > security/selinux/ss/policydb.h | 1 + > > > > > 7 files changed, 57 insertions(+), 1 deletion(-) > > > > > > > > You incorporated some feedback from the v1 patch, but you ignored > > > > some, can you explain why? > > > > > > > > > > I apologize, I missed a couple C++ style comments, I'll fix those and > > > resend, was there anything else? I thought I addressed all of the > > > technical concerns. > > > > My biggest concern wasn't really the style nits (although please do > > fix those), but rather the guts of ebitmap_and() and the use of > > ebitmap_get_bit() instead of something a bit more efficient. Here is > > my original comment: > > > > "Beyond that, since this is an AND operation, could we make better > > use of things like find_first_bit()/ebitmap_start_positive()/ > > ebitmap_next_positive() to skip along one of the bitmaps instead > > of needing to call ebitmap_get_bit() for each bit? I imagine it > > would be quicker that way." > > > > I used ebitmap_for_each_positive_bit() for the outer loop which uses > ebitmap_start_positive() and ebitmap_next_positive(). Sorry, my mistake. Your implementation wasn't quite what I was expecting and on quick glance it looked similar to your previous effort so I assumed it hadn't changed. The v2 variant should be fine. > I suppose I could try to track both lists at the same time and AND the > bitmaps when the startbit is the same but I don't expect this to > really be any kind of bottleneck.
diff --git a/security/selinux/include/security.h b/security/selinux/include/security.h index 111121281c47..ae840634e3c7 100644 --- a/security/selinux/include/security.h +++ b/security/selinux/include/security.h @@ -40,10 +40,11 @@ #define POLICYDB_VERSION_CONSTRAINT_NAMES 29 #define POLICYDB_VERSION_XPERMS_IOCTL 30 #define POLICYDB_VERSION_INFINIBAND 31 +#define POLICYDB_VERSION_GLBLUB 32 /* Range of policy versions we understand*/ #define POLICYDB_VERSION_MIN POLICYDB_VERSION_BASE -#define POLICYDB_VERSION_MAX POLICYDB_VERSION_INFINIBAND +#define POLICYDB_VERSION_MAX POLICYDB_VERSION_GLBLUB /* Mask for just the mount related flags */ #define SE_MNTMASK 0x0f diff --git a/security/selinux/ss/context.h b/security/selinux/ss/context.h index 2260c44a568c..0a0fbcc0d90c 100644 --- a/security/selinux/ss/context.h +++ b/security/selinux/ss/context.h @@ -95,6 +95,34 @@ static inline int mls_context_cpy_high(struct context *dst, struct context *src) return rc; } + +static inline int mls_context_glblub(struct context *dst, struct context *c1, struct context *c2) +{ + struct mls_range *dr = &dst->range, *r1 = &c1->range, *r2 = &c2->range; + int rc = 0; + + if (r1->level[1].sens < r2->level[0].sens || r2->level[1].sens < r1->level[0].sens) + /* These ranges have no common sensitivities */ + return -1; + + // Take the greatest of the low + dr->level[0].sens = max(r1->level[0].sens, r2->level[0].sens); + + // Take the least of the high + dr->level[1].sens = min(r1->level[1].sens, r2->level[1].sens); + + rc = ebitmap_and(&dr->level[0].cat, &r1->level[0].cat, &r2->level[0].cat); + if (rc) + goto out; + + rc = ebitmap_and(&dr->level[1].cat, &r1->level[1].cat, &r2->level[1].cat); + if (rc) + goto out; + +out: + return rc; +} + static inline int mls_context_cmp(struct context *c1, struct context *c2) { return ((c1->range.level[0].sens == c2->range.level[0].sens) && diff --git a/security/selinux/ss/ebitmap.c b/security/selinux/ss/ebitmap.c index 09929fc5ab47..c0a9f8ecffc3 100644 --- a/security/selinux/ss/ebitmap.c +++ b/security/selinux/ss/ebitmap.c @@ -77,6 +77,24 @@ int ebitmap_cpy(struct ebitmap *dst, struct ebitmap *src) return 0; } +int ebitmap_and(struct ebitmap *dst, struct ebitmap *e1, struct ebitmap *e2) +{ + struct ebitmap_node *n; + int bit; + + ebitmap_init(dst); + + ebitmap_for_each_positive_bit(e1, n, bit) { + if (ebitmap_get_bit(e2, bit)) { + int rc = ebitmap_set_bit(dst, bit, 1); + if (rc < 0) + return rc; + } + } + return 0; +} + + #ifdef CONFIG_NETLABEL /** * ebitmap_netlbl_export - Export an ebitmap into a NetLabel category bitmap diff --git a/security/selinux/ss/ebitmap.h b/security/selinux/ss/ebitmap.h index 6aa7cf6a2197..9a23b81b8832 100644 --- a/security/selinux/ss/ebitmap.h +++ b/security/selinux/ss/ebitmap.h @@ -124,6 +124,7 @@ static inline void ebitmap_node_clr_bit(struct ebitmap_node *n, int ebitmap_cmp(struct ebitmap *e1, struct ebitmap *e2); int ebitmap_cpy(struct ebitmap *dst, struct ebitmap *src); +int ebitmap_and(struct ebitmap *dst, struct ebitmap *e1, struct ebitmap *e2); int ebitmap_contains(struct ebitmap *e1, struct ebitmap *e2, u32 last_e2bit); int ebitmap_get_bit(struct ebitmap *e, unsigned long bit); int ebitmap_set_bit(struct ebitmap *e, unsigned long bit, int value); diff --git a/security/selinux/ss/mls.c b/security/selinux/ss/mls.c index 5e05f5b902d7..76c8ad014ac9 100644 --- a/security/selinux/ss/mls.c +++ b/security/selinux/ss/mls.c @@ -529,6 +529,8 @@ int mls_compute_sid(struct policydb *p, return mls_context_cpy_high(newcontext, tcontext); case DEFAULT_TARGET_LOW_HIGH: return mls_context_cpy(newcontext, tcontext); + case DEFAULT_GLBLUB: + return mls_context_glblub(newcontext, scontext, tcontext); } /* Fallthrough */ diff --git a/security/selinux/ss/policydb.c b/security/selinux/ss/policydb.c index f8efaa9f647c..1b59f72effbb 100644 --- a/security/selinux/ss/policydb.c +++ b/security/selinux/ss/policydb.c @@ -160,6 +160,11 @@ static struct policydb_compat_info policydb_compat[] = { .sym_num = SYM_NUM, .ocon_num = OCON_NUM, }, + { + .version = POLICYDB_VERSION_GLBLUB, + .sym_num = SYM_NUM, + .ocon_num = OCON_NUM, + }, }; static struct policydb_compat_info *policydb_lookup_compat(int version) diff --git a/security/selinux/ss/policydb.h b/security/selinux/ss/policydb.h index fcc6366b447f..0c41d0b4da96 100644 --- a/security/selinux/ss/policydb.h +++ b/security/selinux/ss/policydb.h @@ -69,6 +69,7 @@ struct class_datum { #define DEFAULT_TARGET_LOW 4 #define DEFAULT_TARGET_HIGH 5 #define DEFAULT_TARGET_LOW_HIGH 6 +#define DEFAULT_GLBLUB 7 char default_range; };
A policy developer can now specify glblub as a default_range default and the computed transition will be the intersection of the mls range of the two contexts. The glb (greatest lower bound) lub (lowest upper bound) of a range is calculated as the greater of the low sensitivities and the lower of the high sensitivities and the and of each category bitmap. This can be used by MLS solution developers to compute a context that satisfies, for example, the range of a network interface and the range of a user logging in. Some examples are: User Permitted Range | Network Device Label | Computed Label ---------------------|----------------------|---------------- S0-S1:c0.c12 | S0 | S0 S0-S1:c0.c12 | S0-S1:c0.c1024 | S0-S1:c0.c12 S0-S4:c0.c512 | S1-S1:c0.c1024 | S1-S1:c0.c512 S0-S16:c0,c2 | S4-S6:c0.c128 | S4-S6:c0,c2 S0-S4 | S2-S6 | S2-S4 S0-S4 | S5-S8 | INVALID S5-S8 | S0-S4 | INVALID S6:c0,c2-S7:c4,c5 | S0:c2,c4-S6:c5.c100 | S6:c2-S6:c5 Signed-off-by: Joshua Brindle <joshua.brindle@crunchydata.com> --- security/selinux/include/security.h | 3 ++- security/selinux/ss/context.h | 28 ++++++++++++++++++++++++++++ security/selinux/ss/ebitmap.c | 18 ++++++++++++++++++ security/selinux/ss/ebitmap.h | 1 + security/selinux/ss/mls.c | 2 ++ security/selinux/ss/policydb.c | 5 +++++ security/selinux/ss/policydb.h | 1 + 7 files changed, 57 insertions(+), 1 deletion(-)