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-rw-r--r--src/core/namespace.c118
1 files changed, 76 insertions, 42 deletions
diff --git a/src/core/namespace.c b/src/core/namespace.c
index 356d3c8121..d3ab2e8e3e 100644
--- a/src/core/namespace.c
+++ b/src/core/namespace.c
@@ -29,6 +29,7 @@
#include "alloc-util.h"
#include "dev-setup.h"
#include "fd-util.h"
+#include "fs-util.h"
#include "loopback-setup.h"
#include "missing.h"
#include "mkdir.h"
@@ -57,9 +58,9 @@ typedef enum MountMode {
} MountMode;
typedef struct BindMount {
- const char *path;
+ const char *path; /* stack memory, doesn't need to be freed explicitly */
+ char *chased; /* malloc()ed memory, needs to be freed */
MountMode mode;
- bool done;
bool ignore;
} BindMount;
@@ -71,7 +72,6 @@ static int append_mounts(BindMount **p, char **strv, MountMode mode) {
STRV_FOREACH(i, strv) {
(*p)->ignore = false;
- (*p)->done = false;
if ((mode == INACCESSIBLE || mode == READONLY || mode == READWRITE) && (*i)[0] == '-') {
(*p)->ignore = true;
@@ -360,11 +360,8 @@ static int apply_mount(
* inaccessible path. */
(void) umount_recursive(m->path, 0);
- if (lstat(m->path, &target) < 0) {
- if (m->ignore && errno == ENOENT)
- return 0;
+ if (lstat(m->path, &target) < 0)
return log_debug_errno(errno, "Failed to lstat() %s to determine what to mount over it: %m", m->path);
- }
what = mode_to_inaccessible_node(target.st_mode);
if (!what) {
@@ -378,11 +375,8 @@ static int apply_mount(
case READWRITE:
r = path_is_mount_point(m->path, 0);
- if (r < 0) {
- if (m->ignore && errno == ENOENT)
- return 0;
+ if (r < 0)
return log_debug_errno(r, "Failed to determine whether %s is already a mount point: %m", m->path);
- }
if (r > 0) /* Nothing to do here, it is already a mount. We just later toggle the MS_RDONLY bit for the mount point if needed. */
return 0;
@@ -407,12 +401,8 @@ static int apply_mount(
assert(what);
- if (mount(what, m->path, NULL, MS_BIND|MS_REC, NULL) < 0) {
- if (m->ignore && errno == ENOENT)
- return 0;
-
+ if (mount(what, m->path, NULL, MS_BIND|MS_REC, NULL) < 0)
return log_debug_errno(errno, "Failed to mount %s to %s: %m", what, m->path);
- }
log_debug("Successfully mounted %s to %s", what, m->path);
return 0;
@@ -435,12 +425,43 @@ static int make_read_only(BindMount *m, char **blacklist) {
* already stays this way. This improves compatibility with container managers, where we won't attempt to undo
* read-only mounts already applied. */
- if (m->ignore && r == -ENOENT)
- return 0;
-
return r;
}
+static int chase_all_symlinks(const char *root_directory, BindMount *m, unsigned *n) {
+ BindMount *f, *t;
+ int r;
+
+ assert(m);
+ assert(n);
+
+ /* Since mount() will always follow symlinks and we need to take the different root directory into account we
+ * chase the symlinks on our own first. This call wil do so for all entries and remove all entries where we
+ * can't resolve the path, and which have been marked for such removal. */
+
+ for (f = m, t = m; f < m+*n; f++) {
+
+ r = chase_symlinks(f->path, root_directory, &f->chased);
+ if (r == -ENOENT && f->ignore) /* Doesn't exist? Then remove it! */
+ continue;
+ if (r < 0)
+ return log_debug_errno(r, "Failed to chase symlinks for %s: %m", f->path);
+
+ if (path_equal(f->path, f->chased))
+ f->chased = mfree(f->chased);
+ else {
+ log_debug("Chased %s → %s", f->path, f->chased);
+ f->path = f->chased;
+ }
+
+ *t = *f;
+ t++;
+ }
+
+ *n = t - m;
+ return 0;
+}
+
int setup_namespace(
const char* root_directory,
char** read_write_paths,
@@ -456,6 +477,7 @@ int setup_namespace(
unsigned long mount_flags) {
BindMount *m, *mounts = NULL;
+ bool make_slave = false;
unsigned n;
int r = 0;
@@ -475,6 +497,9 @@ int setup_namespace(
((protect_system != PROTECT_SYSTEM_NO ? 3 : 0) +
(protect_system == PROTECT_SYSTEM_FULL ? 1 : 0)));
+ if (root_directory || n > 0)
+ make_slave = true;
+
if (n > 0) {
m = mounts = (BindMount *) alloca0(n * sizeof(BindMount));
r = append_mounts(&m, read_write_paths, READWRITE);
@@ -596,6 +621,13 @@ int setup_namespace(
assert(mounts + n == m);
+ /* Resolve symlinks manually first, as mount() will always follow them relative to the host's
+ * root. Moreover we want to suppress duplicates based on the resolved paths. This of course is a bit
+ * racy. */
+ r = chase_all_symlinks(root_directory, mounts, &n);
+ if (r < 0)
+ goto finish;
+
qsort(mounts, n, sizeof(BindMount), mount_path_compare);
drop_duplicates(mounts, &n);
@@ -603,20 +635,26 @@ int setup_namespace(
drop_nop(mounts, &n);
}
- if (unshare(CLONE_NEWNS) < 0)
- return -errno;
+ if (unshare(CLONE_NEWNS) < 0) {
+ r = -errno;
+ goto finish;
+ }
- if (n > 0 || root_directory) {
+ if (make_slave) {
/* 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)
- return -errno;
+ if (mount(NULL, "/", NULL, MS_SLAVE|MS_REC, NULL) < 0) {
+ r = -errno;
+ goto finish;
+ }
}
if (root_directory) {
/* Turn directory into bind mount */
- if (mount(root_directory, root_directory, NULL, MS_BIND|MS_REC, NULL) < 0)
- return -errno;
+ if (mount(root_directory, root_directory, NULL, MS_BIND|MS_REC, NULL) < 0) {
+ r = -errno;
+ goto finish;
+ }
}
if (n > 0) {
@@ -627,7 +665,7 @@ int setup_namespace(
for (m = mounts; m < mounts + n; ++m) {
r = apply_mount(m, tmp_dir, var_tmp_dir);
if (r < 0)
- goto fail;
+ goto finish;
}
/* Create a blacklist we can pass to bind_mount_recursive() */
@@ -640,34 +678,30 @@ int setup_namespace(
for (m = mounts; m < mounts + n; ++m) {
r = make_read_only(m, blacklist);
if (r < 0)
- goto fail;
+ goto finish;
}
}
if (root_directory) {
/* MS_MOVE does not work on MS_SHARED so the remount MS_SHARED will be done later */
r = mount_move_root(root_directory);
- if (r < 0) /* at this point, we cannot rollback */
- return r;
+ if (r < 0)
+ goto finish;
}
/* Remount / as the desired mode. Not that this will not
* reestablish propagation from our side to the host, since
* what's disconnected is disconnected. */
- if (mount(NULL, "/", NULL, mount_flags | MS_REC, NULL) < 0)
- return -errno; /* at this point, we cannot rollback */
+ if (mount(NULL, "/", NULL, mount_flags | MS_REC, NULL) < 0) {
+ r = -errno;
+ goto finish;
+ }
- return 0;
+ r = 0;
-fail:
- if (n > 0) {
- for (m = mounts; m < mounts + n; ++m) {
- if (!m->done)
- continue;
-
- (void) umount2(m->path, MNT_DETACH);
- }
- }
+finish:
+ for (m = mounts; m < mounts + n; m++)
+ free(m->chased);
return r;
}
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-07-14 10:58:31 +0000