Add basic MLS policy support to mdp. Declares two sensitivities and two categories, defines mls constraints for all permissions requiring dominance (ala MCS), assigns the system-high level to initial SID contexts and the default user level, and assigns system-low level to filesystems. Also reworks the fs_use and genfscon rules to only generate rules for filesystems that are configured in the kernel. In some cases this depends on a specific config option for security xattrs, in other cases security xattrs are unconditionally supported by a given filesystem if the filesystem is enabled, and in some cases the filesystem is always enabled in the kernel. Dropped obsolete pseudo filesystems. NB The list of fs_use_* and genfscon rules emitted by mdp is very incomplete compared to refpolicy or Android sepolicy. We should probably expand it. Usage: scripts/selinux/mdp/mdp -m policy.conf file_contexts checkpolicy -M -o policy policy.conf Then install the resulting policy and file_contexts as usual. Signed-off-by: Stephen Smalley <sds@xxxxxxxxxxxxx> --- v2 adds a second sensitivity, changes the constraints to require dominance rather than equality for all permissions (ala MCS), changes the default level and initial SID contexts to use the highest level, macro-izes the fs_use and genfscon statement generation, and makes them conditional on the relevant kernel configuration option if any. Still only tested that the resulting policy compiles and the file_contexts file passes setfiles -c policy file_contexts validation, not actual loading into a kernel or running it. scripts/selinux/mdp/mdp.c | 137 ++++++++++++++++++++++++++++++-------- 1 file changed, 109 insertions(+), 28 deletions(-) diff --git a/scripts/selinux/mdp/mdp.c b/scripts/selinux/mdp/mdp.c index 073fe7537f6c..3dc47601e2ec 100644 --- a/scripts/selinux/mdp/mdp.c +++ b/scripts/selinux/mdp/mdp.c @@ -33,6 +33,7 @@ #include <unistd.h> #include <string.h> #include <sys/socket.h> +#include <linux/kconfig.h> static void usage(char *name) { @@ -95,10 +96,31 @@ int main(int argc, char *argv[]) } fprintf(fout, "\n"); - /* NOW PRINT OUT MLS STUFF */ + /* print out mls declarations and constraints */ if (mls) { - printf("MLS not yet implemented\n"); - exit(1); + fprintf(fout, "sensitivity s0;\n"); + fprintf(fout, "sensitivity s1;\n"); + fprintf(fout, "dominance { s0 s1 }\n"); + fprintf(fout, "category c0;\n"); + fprintf(fout, "category c1;\n"); + fprintf(fout, "level s0:c0.c1;\n"); + fprintf(fout, "level s1:c0.c1;\n"); +#define SYSTEMLOW "s0" +#define SYSTEMHIGH "s1:c0.c1" + for (i = 0; secclass_map[i].name; i++) { + struct security_class_mapping *map = &secclass_map[i]; + + fprintf(fout, "mlsconstrain %s {\n", map->name); + for (j = 0; map->perms[j]; j++) + fprintf(fout, "\t%s\n", map->perms[j]); + /* + * This requires all subjects and objects to be + * single-level (l2 eq h2), and that the subject + * level dominate the object level (h1 dom h2) + * in order to have any permissions to it. + */ + fprintf(fout, "} (l2 eq h2 and h1 dom h2);\n\n"); + } } /* types, roles, and allows */ @@ -108,34 +130,87 @@ int main(int argc, char *argv[]) for (i = 0; secclass_map[i].name; i++) fprintf(fout, "allow base_t base_t:%s *;\n", secclass_map[i].name); - fprintf(fout, "user user_u roles { base_r };\n"); - fprintf(fout, "\n"); + fprintf(fout, "user user_u roles { base_r }"); + if (mls) + fprintf(fout, " level %s range %s - %s", SYSTEMHIGH, + SYSTEMLOW, SYSTEMHIGH); + fprintf(fout, ";\n"); + +#define USERROLETYPE "user_u:base_r:base_t" /* default sids */ for (i = 1; i < initial_sid_to_string_len; i++) - fprintf(fout, "sid %s user_u:base_r:base_t\n", initial_sid_to_string[i]); + fprintf(fout, "sid %s " USERROLETYPE "%s\n", + initial_sid_to_string[i], mls ? ":" SYSTEMHIGH : ""); fprintf(fout, "\n"); - fprintf(fout, "fs_use_xattr ext2 user_u:base_r:base_t;\n"); - fprintf(fout, "fs_use_xattr ext3 user_u:base_r:base_t;\n"); - fprintf(fout, "fs_use_xattr ext4 user_u:base_r:base_t;\n"); - fprintf(fout, "fs_use_xattr jfs user_u:base_r:base_t;\n"); - fprintf(fout, "fs_use_xattr xfs user_u:base_r:base_t;\n"); - fprintf(fout, "fs_use_xattr reiserfs user_u:base_r:base_t;\n"); - fprintf(fout, "fs_use_xattr jffs2 user_u:base_r:base_t;\n"); - fprintf(fout, "fs_use_xattr gfs2 user_u:base_r:base_t;\n"); - - fprintf(fout, "fs_use_task eventpollfs user_u:base_r:base_t;\n"); - fprintf(fout, "fs_use_task pipefs user_u:base_r:base_t;\n"); - fprintf(fout, "fs_use_task sockfs user_u:base_r:base_t;\n"); - - fprintf(fout, "fs_use_trans mqueue user_u:base_r:base_t;\n"); - fprintf(fout, "fs_use_trans devpts user_u:base_r:base_t;\n"); - fprintf(fout, "fs_use_trans hugetlbfs user_u:base_r:base_t;\n"); - fprintf(fout, "fs_use_trans tmpfs user_u:base_r:base_t;\n"); - fprintf(fout, "fs_use_trans shm user_u:base_r:base_t;\n"); - - fprintf(fout, "genfscon proc / user_u:base_r:base_t\n"); +#define FS_USE(behavior, fstype) \ + fprintf(fout, "fs_use_%s %s " USERROLETYPE "%s;\n", \ + behavior, fstype, mls ? ":" SYSTEMLOW : "") + + /* + * Filesystems whose inode labels can be fetched via getxattr. + */ +#ifdef CONFIG_EXT2_FS_SECURITY + FS_USE("xattr", "ext2"); +#endif +#ifdef CONFIG_EXT3_FS_SECURITY + FS_USE("xattr", "ext3"); +#endif +#ifdef CONFIG_EXT4_FS_SECURITY + FS_USE("xattr", "ext4"); +#endif +#ifdef CONFIG_JFS_SECURITY + FS_USE("xattr", "jfs"); +#endif +#ifdef CONFIG_REISERFS_FS_SECURITY + FS_USE("xattr", "reiserfs"); +#endif +#ifdef CONFIG_JFFS2_FS_SECURITY + FS_USE("xattr", "jffs2"); +#endif +#ifdef CONFIG_XFS_FS + FS_USE("xattr", "xfs"); +#endif +#ifdef CONFIG_GFS2_FS + FS_USE("xattr", "gfs2"); +#endif + + /* + * Filesystems whose inodes are labeled from allocating task. + */ + FS_USE("task", "pipefs"); + FS_USE("task", "sockfs"); +#ifdef CONFIG_POSIX_MQUEUE + FS_USE("task", "mqueue"); +#endif + + /* + * Filesystems whose inode labels are computed from both + * the allocating task and the superblock label. + */ +#ifdef CONFIG_UNIX98_PTYS + FS_USE("trans", "devpts"); +#endif +#ifdef CONFIG_HUGETLBFS + FS_USE("trans", "hugetlbfs"); +#endif +#ifdef CONFIG_TMPFS + FS_USE("trans", "tmpfs"); +#endif + + +#define GENFSCON(fstype, prefix) \ + fprintf(fout, "genfscon %s %s " USERROLETYPE "%s\n", \ + fstype, prefix, mls ? ":" SYSTEMLOW : "") + + /* + * Filesystems whose inodes are labeled from path prefix match + * relative to the filesystem root. Depending on the filesystem, + * only a single label for all inodes may be supported. + */ + GENFSCON("proc", "/"); + GENFSCON("selinuxfs", "/"); fclose(fout); @@ -144,8 +219,14 @@ int main(int argc, char *argv[]) printf("Wrote policy, but cannot open %s for writing\n", ctxout); usage(argv[0]); } - fprintf(fout, "/ user_u:base_r:base_t\n"); - fprintf(fout, "/.* user_u:base_r:base_t\n"); + fprintf(fout, "/ " USERROLETYPE ""); + if (mls) + fprintf(fout, ":s0"); + fprintf(fout, "\n"); + fprintf(fout, "/.* " USERROLETYPE ""); + if (mls) + fprintf(fout, ":s0"); + fprintf(fout, "\n"); fclose(fout); return 0; -- 2.20.1