X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=src%2Fcore%2Fnamespace.c;h=ceeed2e1aede3ed09f143620eeb2fecf1cb5422b;hp=7ac6b381abb772870457a1fe7e3e628f009622d1;hb=c17ec25e4d9bd6c8e8617416f813e25b2ebbafc5;hpb=4d46fec56db73e1d2d01076792f9b8f3231d5cb1

diff --git a/src/core/namespace.c b/src/core/namespace.c
index 7ac6b381a..ceeed2e1a 100644
--- a/src/core/namespace.c
+++ b/src/core/namespace.c
@@ -33,23 +33,27 @@
 
 #include "strv.h"
 #include "util.h"
+#include "path-util.h"
 #include "namespace.h"
 #include "missing.h"
+#include "execute.h"
 
-typedef enum PathMode {
+typedef enum MountMode {
         /* This is ordered by priority! */
         INACCESSIBLE,
         READONLY,
-        PRIVATE,
+        PRIVATE_TMP,
+        PRIVATE_VAR_TMP,
         READWRITE
-} PathMode;
+} MountMode;
 
-typedef struct Path {
+typedef struct BindMount {
         const char *path;
-        PathMode mode;
-} Path;
+        MountMode mode;
+        bool done;
+} BindMount;
 
-static int append_paths(Path **p, char **strv, PathMode mode) {
+static int append_mounts(BindMount **p, char **strv, MountMode mode) {
         char **i;
 
         STRV_FOREACH(i, strv) {
@@ -65,8 +69,8 @@ static int append_paths(Path **p, char **strv, PathMode mode) {
         return 0;
 }
 
-static int path_compare(const void *a, const void *b) {
-        const Path *p = a, *q = b;
+static int mount_path_compare(const void *a, const void *b) {
+        const BindMount *p = a, *q = b;
 
         if (path_equal(p->path, q->path)) {
 
@@ -90,257 +94,191 @@ static int path_compare(const void *a, const void *b) {
         return 0;
 }
 
-static void drop_duplicates(Path *p, unsigned *n, bool *need_inaccessible, bool *need_private) {
-        Path *f, *t, *previous;
+static void drop_duplicates(BindMount *m, unsigned *n) {
+        BindMount *f, *t, *previous;
 
-        assert(p);
+        assert(m);
         assert(n);
-        assert(need_inaccessible);
-        assert(need_private);
 
-        for (f = p, t = p, previous = NULL; f < p+*n; f++) {
+        for (f = m, t = m, previous = NULL; f < m+*n; f++) {
 
+                /* The first one wins */
                 if (previous && path_equal(f->path, previous->path))
                         continue;
 
                 t->path = f->path;
                 t->mode = f->mode;
 
-                if (t->mode == PRIVATE)
-                        *need_private = true;
-
-                if (t->mode == INACCESSIBLE)
-                        *need_inaccessible = true;
-
                 previous = t;
 
                 t++;
         }
 
-        *n = t - p;
+        *n = t - m;
 }
 
-static int apply_mount(Path *p, const char *root_dir, const char *inaccessible_dir, const char *private_dir, unsigned long flags) {
+static int apply_mount(
+                BindMount *m,
+                const char *tmp_dir,
+                const char *var_tmp_dir) {
+
         const char *what;
-        char *where;
         int r;
 
-        assert(p);
-        assert(root_dir);
-        assert(inaccessible_dir);
-        assert(private_dir);
-
-        if (!(where = strappend(root_dir, p->path)))
-                return -ENOMEM;
+        assert(m);
 
-        switch (p->mode) {
+        switch (m->mode) {
 
         case INACCESSIBLE:
-                what = inaccessible_dir;
-                flags |= MS_RDONLY;
+                what = "/run/systemd/inaccessible";
                 break;
 
         case READONLY:
-                flags |= MS_RDONLY;
-                /* Fall through */
-
         case READWRITE:
-                what = p->path;
+                what = m->path;
+                break;
+
+        case PRIVATE_TMP:
+                what = tmp_dir;
                 break;
 
-        case PRIVATE:
-                what = private_dir;
+        case PRIVATE_VAR_TMP:
+                what = var_tmp_dir;
                 break;
 
         default:
                 assert_not_reached("Unknown mode");
         }
 
-        if ((r = mount(what, where, NULL, MS_BIND|MS_REC, NULL)) >= 0) {
-                log_debug("Successfully mounted %s to %s", what, where);
+        assert(what);
 
-                /* The bind mount will always inherit the original
-                 * flags. If we want to set any flag we need
-                 * to do so in a second independent step. */
-                if (flags)
-                        r = mount(NULL, where, NULL, MS_REMOUNT|MS_BIND|MS_REC|flags, NULL);
+        r = mount(what, m->path, NULL, MS_BIND|MS_REC, NULL);
+        if (r >= 0)
+                log_debug("Successfully mounted %s to %s", what, m->path);
 
-                /* Avoid exponential growth of trees */
-                if (r >= 0 && path_equal(p->path, "/"))
-                        r = mount(NULL, where, NULL, MS_REMOUNT|MS_BIND|flags, NULL);
-
-                if (r < 0) {
-                        r = -errno;
-                        umount2(where, MNT_DETACH);
-                }
-        }
-
-        free(where);
         return r;
 }
 
-int setup_namespace(
-                char **writable,
-                char **readable,
-                char **inaccessible,
-                bool private_tmp,
-                unsigned long flags) {
-
-        char
-                tmp_dir[] = "/tmp/systemd-namespace-XXXXXX",
-                root_dir[] = "/tmp/systemd-namespace-XXXXXX/root",
-                old_root_dir[] = "/tmp/systemd-namespace-XXXXXX/root/tmp/old-root-XXXXXX",
-                inaccessible_dir[] = "/tmp/systemd-namespace-XXXXXX/inaccessible",
-                private_dir[] = "/tmp/systemd-namespace-XXXXXX/private";
-
-        Path *paths, *p;
-        unsigned n;
-        bool need_private = false, need_inaccessible = false;
-        bool remove_tmp = false, remove_root = false, remove_old_root = false, remove_inaccessible = false, remove_private = false;
+static int make_read_only(BindMount *m) {
         int r;
-        const char *t;
 
-        n =
-                strv_length(writable) +
-                strv_length(readable) +
-                strv_length(inaccessible) +
-                (private_tmp ? 2 : 1);
+        assert(m);
 
-        if (!(paths = new(Path, n)))
-                return -ENOMEM;
+        if (m->mode != INACCESSIBLE && m->mode != READONLY)
+                return 0;
 
-        p = paths;
-        if ((r = append_paths(&p, writable, READWRITE)) < 0 ||
-            (r = append_paths(&p, readable, READONLY)) < 0 ||
-            (r = append_paths(&p, inaccessible, INACCESSIBLE)) < 0)
-                goto fail;
+        r = mount(NULL, m->path, NULL, MS_BIND|MS_REMOUNT|MS_RDONLY|MS_REC, NULL);
+        if (r < 0)
+                return -errno;
 
-        if (private_tmp) {
-                p->path = "/tmp";
-                p->mode = PRIVATE;
-                p++;
-        }
+        return 0;
+}
 
-        p->path = "/";
-        p->mode = READWRITE;
-        p++;
+int setup_tmpdirs(char **tmp_dir,
+                  char **var_tmp_dir) {
+        int r = 0;
+        char tmp_dir_template[] = "/tmp/systemd-private-XXXXXX",
+             var_tmp_dir_template[] = "/var/tmp/systemd-private-XXXXXX";
 
-        assert(paths + n == p);
+        assert(tmp_dir);
+        assert(var_tmp_dir);
 
-        qsort(paths, n, sizeof(Path), path_compare);
-        drop_duplicates(paths, &n, &need_inaccessible, &need_private);
+        r = create_tmp_dir(tmp_dir_template, 0000, true, tmp_dir);
+        if (r < 0)
+                goto fail2;
 
-        if (!mkdtemp(tmp_dir)) {
-                r = -errno;
-                goto fail;
-        }
-        remove_tmp = true;
+        r = create_tmp_dir(var_tmp_dir_template, 0000, true, var_tmp_dir);
+        if (r < 0)
+                goto fail1;
 
-        memcpy(root_dir, tmp_dir, sizeof(tmp_dir)-1);
-        if (mkdir(root_dir, 0777) < 0) {
-                r = -errno;
-                goto fail;
-        }
-        remove_root = true;
-
-        if (need_inaccessible) {
-                memcpy(inaccessible_dir, tmp_dir, sizeof(tmp_dir)-1);
-                if (mkdir(inaccessible_dir, 0) < 0) {
-                        r = -errno;
-                        goto fail;
-                }
-                remove_inaccessible = true;
-        }
+        return 0;
 
-        if (need_private) {
-                mode_t u;
+fail1:
+        rmdir(*tmp_dir);
+        free(*tmp_dir);
+        *tmp_dir = NULL;
 
-                memcpy(private_dir, tmp_dir, sizeof(tmp_dir)-1);
+fail2:
+        return r;
+}
 
-                u = umask(0000);
-                if (mkdir(private_dir, 0777 + S_ISVTX) < 0) {
-                        umask(u);
+int setup_namespace(char** read_write_dirs,
+                    char** read_only_dirs,
+                    char** inaccessible_dirs,
+                    char* tmp_dir,
+                    char* var_tmp_dir,
+                    bool private_tmp,
+                    unsigned mount_flags) {
 
-                        r = -errno;
-                        goto fail;
-                }
+        unsigned n = strv_length(read_write_dirs) +
+                     strv_length(read_only_dirs) +
+                     strv_length(inaccessible_dirs) +
+                     (private_tmp ? 2 : 0);
+        BindMount *m, *mounts;
+        int r = 0;
 
-                umask(u);
-                remove_private = true;
-        }
+        if (!mount_flags)
+                mount_flags = MS_SHARED;
 
         if (unshare(CLONE_NEWNS) < 0) {
                 r = -errno;
                 goto fail;
         }
 
-        /* Remount / as SLAVE so that nothing mounted in the namespace
+        m = mounts = (BindMount *) alloca(n * sizeof(BindMount));
+        if ((r = append_mounts(&m, read_write_dirs, READWRITE)) < 0 ||
+                (r = append_mounts(&m, read_only_dirs, READONLY)) < 0 ||
+                (r = append_mounts(&m, inaccessible_dirs, INACCESSIBLE)) < 0)
+                goto fail;
+
+        if (private_tmp) {
+                m->path = "/tmp";
+                m->mode = PRIVATE_TMP;
+                m++;
+
+                m->path = "/var/tmp";
+                m->mode = PRIVATE_VAR_TMP;
+                m++;
+        }
+
+        assert(mounts + n == m);
+
+        qsort(mounts, n, sizeof(BindMount), mount_path_compare);
+        drop_duplicates(mounts, &n);
+
+        /* Remount / as SLAVE so that nothing now mounted in the namespace
            shows up in the parent */
         if (mount(NULL, "/", NULL, MS_SLAVE|MS_REC, NULL) < 0) {
                 r = -errno;
                 goto fail;
         }
 
-        for (p = paths; p < paths + n; p++)
-                if ((r = apply_mount(p, root_dir, inaccessible_dir, private_dir, flags)) < 0)
+        for (m = mounts; m < mounts + n; ++m) {
+                r = apply_mount(m, tmp_dir, var_tmp_dir);
+                if (r < 0)
                         goto undo_mounts;
-
-        memcpy(old_root_dir, tmp_dir, sizeof(tmp_dir)-1);
-        if (!mkdtemp(old_root_dir)) {
-                r = -errno;
-                goto undo_mounts;
         }
-        remove_old_root = true;
 
-        if (chdir(root_dir) < 0) {
-                r = -errno;
-                goto undo_mounts;
+        for (m = mounts; m < mounts + n; ++m) {
+                r = make_read_only(m);
+                if (r < 0)
+                        goto undo_mounts;
         }
 
-        if (pivot_root(root_dir, old_root_dir) < 0) {
+        /* Remount / as the desired mode */
+        if (mount(NULL, "/", NULL, mount_flags | MS_REC, NULL) < 0) {
                 r = -errno;
                 goto undo_mounts;
         }
 
-        t = old_root_dir + sizeof(root_dir) - 1;
-        if (umount2(t, MNT_DETACH) < 0)
-                /* At this point it's too late to turn anything back,
-                 * since we are already in the new root. */
-                return -errno;
-
-        if (rmdir(t) < 0)
-                return -errno;
-
         return 0;
 
 undo_mounts:
-
-        for (p--; p >= paths; p--) {
-                char full_path[PATH_MAX];
-
-                snprintf(full_path, sizeof(full_path), "%s%s", root_dir, p->path);
-                char_array_0(full_path);
-
-                umount2(full_path, MNT_DETACH);
+        for (m = mounts; m < mounts + n; ++m) {
+                if (m->done)
+                        umount2(m->path, MNT_DETACH);
         }
 
 fail:
-        if (remove_old_root)
-                rmdir(old_root_dir);
-
-        if (remove_inaccessible)
-                rmdir(inaccessible_dir);
-
-        if (remove_private)
-                rmdir(private_dir);
-
-        if (remove_root)
-                rmdir(root_dir);
-
-        if (remove_tmp)
-                rmdir(tmp_dir);
-
-             free(paths);
-
         return r;
 }