| Message ID | 20190405183850.10861-1-joshua.brindle@crunchydata.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v4] Add security_validatetrans support | expand |
On Fri, Apr 5, 2019 at 11:39 AM Joshua Brindle <joshua.brindle@crunchydata.com> wrote: > > It seems validatetrans support was never added to libselinux, despite being added to > selinuxfs in kernel version 4.5 > > There is a utility to test, however the targeted policy has no validatetrans rules so some must be added: > > $ cat validatetrans.cil > (mlsvalidatetrans db_table (and (or (or (or (eq l1 l2) (and (eq t3 unconfined_t) (domby l1 l2))) (and (eq t3 unconfined_t) (dom l1 l2))) (and (eq t3 unconfined_t) (incomp l1 l2))) (or (or (or (eq l1 h2) (and (eq t3 unconfined_t) (domby h1 h2))) (and (eq t3 unconfined_t) (dom h1 h2))) (and (eq t3 unconfined_t) (incomp h1 h2))))) > > $ sudo semodule -i validatetrans.cil > > $ ./validatetrans system_u:system_r:kernel_t:s0 system_u:system_r:init_t:s0:c0 db_table system_u:system_r: # invalid context here > opening /sys/fs/selinux/validatetrans > security_validatetrans returned -1 errno: Invalid argument > > $ ./validatetrans system_u:system_r:kernel_t:s0 system_u:system_r:init_t:s0:c0 db_table system_u:system_r:init_t:s0 > opening /sys/fs/selinux/validatetrans > security_validatetrans returned -1 errno: Operation not permitted > > $ ./validatetrans system_u:system_r:kernel_t:s0 system_u:system_r:init_t:s0:c0 db_table system_u:system_r:unconfined_t:s0 > opening /sys/fs/selinux/validatetrans > security_validatetrans returned 0 errno: Success > > Signed-off-by: Joshua Brindle <joshua.brindle@crunchydata.com> > --- > libselinux/include/selinux/selinux.h | 13 +++ > libselinux/man/man3/security_compute_av.3 | 13 ++- > libselinux/man/man3/security_validatetrans.c | 1 + > .../man/man3/security_validatetrans_raw.c | 1 + > libselinux/src/selinux_internal.h | 2 + > libselinux/src/validatetrans.c | 94 +++++++++++++++++++ > libselinux/utils/.gitignore | 1 + > libselinux/utils/validatetrans.c | 30 ++++++ > 8 files changed, 154 insertions(+), 1 deletion(-) > create mode 100644 libselinux/man/man3/security_validatetrans.c > create mode 100644 libselinux/man/man3/security_validatetrans_raw.c > create mode 100644 libselinux/src/validatetrans.c > create mode 100644 libselinux/utils/validatetrans.c > > diff --git a/libselinux/include/selinux/selinux.h b/libselinux/include/selinux/selinux.h > index a34d54fc..f54f236b 100644 > --- a/libselinux/include/selinux/selinux.h > +++ b/libselinux/include/selinux/selinux.h > @@ -255,6 +255,19 @@ extern int security_compute_user_raw(const char * scon, > const char *username, > char *** con); > > +/* Validate a transition. This determines whether a transition from scon to newcon > + using tcon as the target for object class tclass is valid in the loaded policy. > + This checks against the mlsvalidatetrans and validatetrans constraints in the loaded policy. > + Returns 0 if allowed and -1 if an error occured with errno set */ > +extern int security_validatetrans(const char *scon, > + const char *tcon, > + security_class_t tclass, > + const char *newcon); > +extern int security_validatetrans_raw(const char *scon, > + const char *tcon, > + security_class_t tclass, > + const char *newcon); > + > /* Load a policy configuration. */ > extern int security_load_policy(void *data, size_t len); > > diff --git a/libselinux/man/man3/security_compute_av.3 b/libselinux/man/man3/security_compute_av.3 > index 2aade5fe..a7181bed 100644 > --- a/libselinux/man/man3/security_compute_av.3 > +++ b/libselinux/man/man3/security_compute_av.3 > @@ -1,7 +1,7 @@ > .TH "security_compute_av" "3" "1 January 2004" "russell@coker.com.au" "SELinux API documentation" > .SH "NAME" > security_compute_av, security_compute_av_flags, security_compute_create, security_compute_create_name, security_compute_relabel, > -security_compute_member, security_compute_user, security_get_initial_context \- query > +security_compute_member, security_compute_user, security_validatetrans, security_get_initial_context \- query > the SELinux policy database in the kernel > . > .SH "SYNOPSIS" > @@ -35,6 +35,10 @@ the SELinux policy database in the kernel > .sp > .BI "int security_compute_user_raw(char *" scon ", const char *" username ", char ***" con ); > .sp > +.BI "int security_validatetrans(char *" scon ", const char *" tcon ", security_class_t "tclass ", char *" newcon ); > +.sp > +.BI "int security_validatetrans_raw(char *" scon ", const char *" tcon ", security_class_t "tclass ", char *" newcon ); > +.sp > .BI "int security_get_initial_context(const char *" name ", char **" con ); > .sp > .BI "int security_get_initial_context_raw(const char *" name ", char **" con ); > @@ -100,6 +104,12 @@ is used to determine the set of user contexts that can be reached from a > source context. It is mainly used by > .BR get_ordered_context_list (). > > +.BR security_validatetrans () > +is used to determine if a transition from scon to newcon using tcon as the object > +is valid for object class tclass. This checks against the mlsvalidatetrans and > +validatetrans constraints in the loaded policy. Returns 0 if allowed, and -1 > +if an error occured with errno set. > + > .BR security_get_initial_context () > is used to get the context of a kernel initial security identifier specified by > .I name > @@ -111,6 +121,7 @@ is used to get the context of a kernel initial security identifier specified by > .BR \%security_compute_relabel_raw (), > .BR \%security_compute_member_raw (), > .BR \%security_compute_user_raw () > +.BR \%security_validatetrans_raw () > and > .BR \%security_get_initial_context_raw () > behave identically to their non-raw counterparts but do not perform context > diff --git a/libselinux/man/man3/security_validatetrans.c b/libselinux/man/man3/security_validatetrans.c > new file mode 100644 > index 00000000..a60bca4d > --- /dev/null > +++ b/libselinux/man/man3/security_validatetrans.c > @@ -0,0 +1 @@ > +.so man3/security_compute_av.3 > diff --git a/libselinux/man/man3/security_validatetrans_raw.c b/libselinux/man/man3/security_validatetrans_raw.c > new file mode 100644 > index 00000000..a60bca4d > --- /dev/null > +++ b/libselinux/man/man3/security_validatetrans_raw.c > @@ -0,0 +1 @@ > +.so man3/security_compute_av.3 > diff --git a/libselinux/src/selinux_internal.h b/libselinux/src/selinux_internal.h > index 70b5025d..acd59c7c 100644 > --- a/libselinux/src/selinux_internal.h > +++ b/libselinux/src/selinux_internal.h > @@ -29,6 +29,8 @@ hidden_proto(selinux_mkload_policy) > hidden_proto(security_compute_create_name_raw) > hidden_proto(security_compute_member_raw) > hidden_proto(security_compute_relabel_raw) > + hidden_proto(security_validatetrans) > + hidden_proto(security_validatetrans_raw) > hidden_proto(is_selinux_enabled) > hidden_proto(is_selinux_mls_enabled) > hidden_proto(freecon) > diff --git a/libselinux/src/validatetrans.c b/libselinux/src/validatetrans.c > new file mode 100644 > index 00000000..9e745a91 > --- /dev/null > +++ b/libselinux/src/validatetrans.c > @@ -0,0 +1,94 @@ > +#include <unistd.h> > +#include <sys/types.h> > +#include <fcntl.h> > +#include <stdlib.h> > +#include <stdio.h> > +#include <errno.h> > +#include <string.h> > +#include <limits.h> > +#include "selinux_internal.h" > +#include "policy.h" > +#include "mapping.h" > + > +int security_validatetrans_raw(const char *scon, > + const char *tcon, > + security_class_t tclass, > + const char *newcon) > +{ > + char path[PATH_MAX]; > + char *buf = NULL; > + int size, bufsz; > + int fd, ret = -1; > + errno = ENOENT; > + > + if (!selinux_mnt) { > + return -1; > + } > + > + snprintf(path, sizeof path, "%s/validatetrans", selinux_mnt); > + fd = open(path, O_WRONLY | O_CLOEXEC); > + if (fd < 0) { > + return -1; > + } > + > + errno = EINVAL; > + size = selinux_page_size; > + buf = malloc(size); > + if (!buf) { > + goto out; > + } > + > + bufsz = snprintf(buf, size, "%s %s %hu %s", scon, tcon, unmap_class(tclass), newcon); > + if (bufsz >= size) { I guess this is fine, I don't think the negative return conditions can exist unless you bork the format string. > + // It got truncated > + goto out; > + } > + > + // clear errno for write() > + errno = 0; > + ret = write(fd, buf, strlen(buf)); > + if (ret > 0) { > + // The kernel returns the bytes written on success, not 0 as noted in the commit message > + ret = 0; > + } > +out: > + free(buf); > + close(fd); > + return ret; > +} > + > +hidden_def(security_validatetrans_raw) > + > +int security_validatetrans(const char *scon, > + const char *tcon, > + security_class_t tclass, > + const char *newcon) > +{ > + int ret = -1; > + char *rscon = NULL; > + char *rtcon = NULL; > + char *rnewcon = NULL; > + > + if (selinux_trans_to_raw_context(scon, &rscon)) { > + goto out; > + } > + > + if (selinux_trans_to_raw_context(tcon, &rtcon)) { > + goto out; > + } > + > + if (selinux_trans_to_raw_context(newcon, &rnewcon)) { > + goto out; > + } > + > + ret = security_validatetrans_raw(rscon, rtcon, tclass, rnewcon); > + > +out: > + freecon(rnewcon); > + freecon(rtcon); > + freecon(rscon); > + > + return ret; > +} > + > +hidden_def(security_validatetrans) > diff --git a/libselinux/utils/.gitignore b/libselinux/utils/.gitignore > index 5cd01025..aba18a3c 100644 > --- a/libselinux/utils/.gitignore > +++ b/libselinux/utils/.gitignore > @@ -25,3 +25,4 @@ setenforce > setfilecon > togglesebool > selinux_check_access > +validatetrans > diff --git a/libselinux/utils/validatetrans.c b/libselinux/utils/validatetrans.c > new file mode 100644 > index 00000000..1db33e66 > --- /dev/null > +++ b/libselinux/utils/validatetrans.c > @@ -0,0 +1,30 @@ > +#include <unistd.h> > +#include <sys/types.h> > +#include <stdio.h> > +#include <stdlib.h> > +#include <string.h> > +#include <errno.h> > +#include <selinux/selinux.h> > + > +int main(int argc, char **argv) > +{ > + security_class_t tclass; > + int ret; > + > + if (argc != 5) { > + fprintf(stderr, "usage: %s scontext tcontext tclass newcontext\n", > + argv[0]); > + exit(1); > + } > + > + tclass = string_to_security_class(argv[3]); > + if (!tclass) { > + fprintf(stderr, "%s: invalid class '%s'\n", argv[0], argv[3]); > + exit(2); > + } > + > + ret = security_validatetrans(argv[1], argv[2], tclass, argv[4]); > + printf("security_validatetrans returned %d errno: %s\n", ret, strerror(errno)); > + > + return ret; > +} > -- > 2.17.2 > ack
<snip> > > I guess this is fine, I don't think the negative return conditions can > exist unless you bork the format > string. > I'll fix it.
diff --git a/libselinux/include/selinux/selinux.h b/libselinux/include/selinux/selinux.h index a34d54fc..f54f236b 100644 --- a/libselinux/include/selinux/selinux.h +++ b/libselinux/include/selinux/selinux.h @@ -255,6 +255,19 @@ extern int security_compute_user_raw(const char * scon, const char *username, char *** con); +/* Validate a transition. This determines whether a transition from scon to newcon + using tcon as the target for object class tclass is valid in the loaded policy. + This checks against the mlsvalidatetrans and validatetrans constraints in the loaded policy. + Returns 0 if allowed and -1 if an error occured with errno set */ +extern int security_validatetrans(const char *scon, + const char *tcon, + security_class_t tclass, + const char *newcon); +extern int security_validatetrans_raw(const char *scon, + const char *tcon, + security_class_t tclass, + const char *newcon); + /* Load a policy configuration. */ extern int security_load_policy(void *data, size_t len); diff --git a/libselinux/man/man3/security_compute_av.3 b/libselinux/man/man3/security_compute_av.3 index 2aade5fe..a7181bed 100644 --- a/libselinux/man/man3/security_compute_av.3 +++ b/libselinux/man/man3/security_compute_av.3 @@ -1,7 +1,7 @@ .TH "security_compute_av" "3" "1 January 2004" "russell@coker.com.au" "SELinux API documentation" .SH "NAME" security_compute_av, security_compute_av_flags, security_compute_create, security_compute_create_name, security_compute_relabel, -security_compute_member, security_compute_user, security_get_initial_context \- query +security_compute_member, security_compute_user, security_validatetrans, security_get_initial_context \- query the SELinux policy database in the kernel . .SH "SYNOPSIS" @@ -35,6 +35,10 @@ the SELinux policy database in the kernel .sp .BI "int security_compute_user_raw(char *" scon ", const char *" username ", char ***" con ); .sp +.BI "int security_validatetrans(char *" scon ", const char *" tcon ", security_class_t "tclass ", char *" newcon ); +.sp +.BI "int security_validatetrans_raw(char *" scon ", const char *" tcon ", security_class_t "tclass ", char *" newcon ); +.sp .BI "int security_get_initial_context(const char *" name ", char **" con ); .sp .BI "int security_get_initial_context_raw(const char *" name ", char **" con ); @@ -100,6 +104,12 @@ is used to determine the set of user contexts that can be reached from a source context. It is mainly used by .BR get_ordered_context_list (). +.BR security_validatetrans () +is used to determine if a transition from scon to newcon using tcon as the object +is valid for object class tclass. This checks against the mlsvalidatetrans and +validatetrans constraints in the loaded policy. Returns 0 if allowed, and -1 +if an error occured with errno set. + .BR security_get_initial_context () is used to get the context of a kernel initial security identifier specified by .I name @@ -111,6 +121,7 @@ is used to get the context of a kernel initial security identifier specified by .BR \%security_compute_relabel_raw (), .BR \%security_compute_member_raw (), .BR \%security_compute_user_raw () +.BR \%security_validatetrans_raw () and .BR \%security_get_initial_context_raw () behave identically to their non-raw counterparts but do not perform context diff --git a/libselinux/man/man3/security_validatetrans.c b/libselinux/man/man3/security_validatetrans.c new file mode 100644 index 00000000..a60bca4d --- /dev/null +++ b/libselinux/man/man3/security_validatetrans.c @@ -0,0 +1 @@ +.so man3/security_compute_av.3 diff --git a/libselinux/man/man3/security_validatetrans_raw.c b/libselinux/man/man3/security_validatetrans_raw.c new file mode 100644 index 00000000..a60bca4d --- /dev/null +++ b/libselinux/man/man3/security_validatetrans_raw.c @@ -0,0 +1 @@ +.so man3/security_compute_av.3 diff --git a/libselinux/src/selinux_internal.h b/libselinux/src/selinux_internal.h index 70b5025d..acd59c7c 100644 --- a/libselinux/src/selinux_internal.h +++ b/libselinux/src/selinux_internal.h @@ -29,6 +29,8 @@ hidden_proto(selinux_mkload_policy) hidden_proto(security_compute_create_name_raw) hidden_proto(security_compute_member_raw) hidden_proto(security_compute_relabel_raw) + hidden_proto(security_validatetrans) + hidden_proto(security_validatetrans_raw) hidden_proto(is_selinux_enabled) hidden_proto(is_selinux_mls_enabled) hidden_proto(freecon) diff --git a/libselinux/src/validatetrans.c b/libselinux/src/validatetrans.c new file mode 100644 index 00000000..9e745a91 --- /dev/null +++ b/libselinux/src/validatetrans.c @@ -0,0 +1,94 @@ +#include <unistd.h> +#include <sys/types.h> +#include <fcntl.h> +#include <stdlib.h> +#include <stdio.h> +#include <errno.h> +#include <string.h> +#include <limits.h> +#include "selinux_internal.h" +#include "policy.h" +#include "mapping.h" + +int security_validatetrans_raw(const char *scon, + const char *tcon, + security_class_t tclass, + const char *newcon) +{ + char path[PATH_MAX]; + char *buf = NULL; + int size, bufsz; + int fd, ret = -1; + errno = ENOENT; + + if (!selinux_mnt) { + return -1; + } + + snprintf(path, sizeof path, "%s/validatetrans", selinux_mnt); + fd = open(path, O_WRONLY | O_CLOEXEC); + if (fd < 0) { + return -1; + } + + errno = EINVAL; + size = selinux_page_size; + buf = malloc(size); + if (!buf) { + goto out; + } + + bufsz = snprintf(buf, size, "%s %s %hu %s", scon, tcon, unmap_class(tclass), newcon); + if (bufsz >= size) { + // It got truncated + goto out; + } + + // clear errno for write() + errno = 0; + ret = write(fd, buf, strlen(buf)); + if (ret > 0) { + // The kernel returns the bytes written on success, not 0 as noted in the commit message + ret = 0; + } +out: + free(buf); + close(fd); + return ret; +} + +hidden_def(security_validatetrans_raw) + +int security_validatetrans(const char *scon, + const char *tcon, + security_class_t tclass, + const char *newcon) +{ + int ret = -1; + char *rscon = NULL; + char *rtcon = NULL; + char *rnewcon = NULL; + + if (selinux_trans_to_raw_context(scon, &rscon)) { + goto out; + } + + if (selinux_trans_to_raw_context(tcon, &rtcon)) { + goto out; + } + + if (selinux_trans_to_raw_context(newcon, &rnewcon)) { + goto out; + } + + ret = security_validatetrans_raw(rscon, rtcon, tclass, rnewcon); + +out: + freecon(rnewcon); + freecon(rtcon); + freecon(rscon); + + return ret; +} + +hidden_def(security_validatetrans) diff --git a/libselinux/utils/.gitignore b/libselinux/utils/.gitignore index 5cd01025..aba18a3c 100644 --- a/libselinux/utils/.gitignore +++ b/libselinux/utils/.gitignore @@ -25,3 +25,4 @@ setenforce setfilecon togglesebool selinux_check_access +validatetrans diff --git a/libselinux/utils/validatetrans.c b/libselinux/utils/validatetrans.c new file mode 100644 index 00000000..1db33e66 --- /dev/null +++ b/libselinux/utils/validatetrans.c @@ -0,0 +1,30 @@ +#include <unistd.h> +#include <sys/types.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <errno.h> +#include <selinux/selinux.h> + +int main(int argc, char **argv) +{ + security_class_t tclass; + int ret; + + if (argc != 5) { + fprintf(stderr, "usage: %s scontext tcontext tclass newcontext\n", + argv[0]); + exit(1); + } + + tclass = string_to_security_class(argv[3]); + if (!tclass) { + fprintf(stderr, "%s: invalid class '%s'\n", argv[0], argv[3]); + exit(2); + } + + ret = security_validatetrans(argv[1], argv[2], tclass, argv[4]); + printf("security_validatetrans returned %d errno: %s\n", ret, strerror(errno)); + + return ret; +}
It seems validatetrans support was never added to libselinux, despite being added to selinuxfs in kernel version 4.5 There is a utility to test, however the targeted policy has no validatetrans rules so some must be added: $ cat validatetrans.cil (mlsvalidatetrans db_table (and (or (or (or (eq l1 l2) (and (eq t3 unconfined_t) (domby l1 l2))) (and (eq t3 unconfined_t) (dom l1 l2))) (and (eq t3 unconfined_t) (incomp l1 l2))) (or (or (or (eq l1 h2) (and (eq t3 unconfined_t) (domby h1 h2))) (and (eq t3 unconfined_t) (dom h1 h2))) (and (eq t3 unconfined_t) (incomp h1 h2))))) $ sudo semodule -i validatetrans.cil $ ./validatetrans system_u:system_r:kernel_t:s0 system_u:system_r:init_t:s0:c0 db_table system_u:system_r: # invalid context here opening /sys/fs/selinux/validatetrans security_validatetrans returned -1 errno: Invalid argument $ ./validatetrans system_u:system_r:kernel_t:s0 system_u:system_r:init_t:s0:c0 db_table system_u:system_r:init_t:s0 opening /sys/fs/selinux/validatetrans security_validatetrans returned -1 errno: Operation not permitted $ ./validatetrans system_u:system_r:kernel_t:s0 system_u:system_r:init_t:s0:c0 db_table system_u:system_r:unconfined_t:s0 opening /sys/fs/selinux/validatetrans security_validatetrans returned 0 errno: Success Signed-off-by: Joshua Brindle <joshua.brindle@crunchydata.com> --- libselinux/include/selinux/selinux.h | 13 +++ libselinux/man/man3/security_compute_av.3 | 13 ++- libselinux/man/man3/security_validatetrans.c | 1 + .../man/man3/security_validatetrans_raw.c | 1 + libselinux/src/selinux_internal.h | 2 + libselinux/src/validatetrans.c | 94 +++++++++++++++++++ libselinux/utils/.gitignore | 1 + libselinux/utils/validatetrans.c | 30 ++++++ 8 files changed, 154 insertions(+), 1 deletion(-) create mode 100644 libselinux/man/man3/security_validatetrans.c create mode 100644 libselinux/man/man3/security_validatetrans_raw.c create mode 100644 libselinux/src/validatetrans.c create mode 100644 libselinux/utils/validatetrans.c