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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 15:35:18 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 15:35:18 +0000 |
commit | b750101eb236130cf056c675997decbac904cc49 (patch) | |
tree | a5df1a06754bdd014cb975c051c83b01c9a97532 /src/shared/dev-setup.c | |
parent | Initial commit. (diff) | |
download | systemd-upstream.tar.xz systemd-upstream.zip |
Adding upstream version 252.22.upstream/252.22upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | src/shared/dev-setup.c | 120 |
1 files changed, 120 insertions, 0 deletions
diff --git a/src/shared/dev-setup.c b/src/shared/dev-setup.c new file mode 100644 index 0000000..a340524 --- /dev/null +++ b/src/shared/dev-setup.c @@ -0,0 +1,120 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ + +#include <errno.h> +#include <stdlib.h> +#include <unistd.h> + +#include "alloc-util.h" +#include "dev-setup.h" +#include "label.h" +#include "log.h" +#include "mkdir-label.h" +#include "nulstr-util.h" +#include "path-util.h" +#include "umask-util.h" +#include "user-util.h" + +int dev_setup(const char *prefix, uid_t uid, gid_t gid) { + static const char symlinks[] = + "-/proc/kcore\0" "/dev/core\0" + "/proc/self/fd\0" "/dev/fd\0" + "/proc/self/fd/0\0" "/dev/stdin\0" + "/proc/self/fd/1\0" "/dev/stdout\0" + "/proc/self/fd/2\0" "/dev/stderr\0"; + + const char *j, *k; + int r; + + NULSTR_FOREACH_PAIR(j, k, symlinks) { + _cleanup_free_ char *link_name = NULL; + const char *n; + + if (j[0] == '-') { + j++; + + if (access(j, F_OK) < 0) + continue; + } + + if (prefix) { + link_name = path_join(prefix, k); + if (!link_name) + return -ENOMEM; + + n = link_name; + } else + n = k; + + r = symlink_label(j, n); + if (r < 0) + log_debug_errno(r, "Failed to symlink %s to %s: %m", j, n); + + if (uid != UID_INVALID || gid != GID_INVALID) + if (lchown(n, uid, gid) < 0) + log_debug_errno(errno, "Failed to chown %s: %m", n); + } + + return 0; +} + +int make_inaccessible_nodes( + const char *parent_dir, + uid_t uid, + gid_t gid) { + + static const struct { + const char *name; + mode_t mode; + } table[] = { + { "inaccessible", S_IFDIR | 0755 }, + { "inaccessible/reg", S_IFREG | 0000 }, + { "inaccessible/dir", S_IFDIR | 0000 }, + { "inaccessible/fifo", S_IFIFO | 0000 }, + { "inaccessible/sock", S_IFSOCK | 0000 }, + + /* The following two are likely to fail if we lack the privs for it (for example in an userns + * environment, if CAP_SYS_MKNOD is missing, or if a device node policy prohibits creation of + * device nodes with a major/minor of 0). But that's entirely fine. Consumers of these files + * should implement falling back to use a different node then, for example + * <root>/inaccessible/sock, which is close enough in behaviour and semantics for most uses. + */ + { "inaccessible/chr", S_IFCHR | 0000 }, + { "inaccessible/blk", S_IFBLK | 0000 }, + }; + + int r; + + if (!parent_dir) + parent_dir = "/run/systemd"; + + BLOCK_WITH_UMASK(0000); + + /* Set up inaccessible (and empty) file nodes of all types. This are used to as mount sources for over-mounting + * ("masking") file nodes that shall become inaccessible and empty for specific containers or services. We try + * to lock down these nodes as much as we can, but otherwise try to match them as closely as possible with the + * underlying file, i.e. in the best case we offer the same node type as the underlying node. */ + + for (size_t i = 0; i < ELEMENTSOF(table); i++) { + _cleanup_free_ char *path = NULL; + + path = path_join(parent_dir, table[i].name); + if (!path) + return log_oom(); + + if (S_ISDIR(table[i].mode)) + r = mkdir_label(path, table[i].mode & 07777); + else + r = mknod_label(path, table[i].mode, makedev(0, 0)); + if (r < 0) { + log_debug_errno(r, "Failed to create '%s', ignoring: %m", path); + continue; + } + + if (uid != UID_INVALID || gid != GID_INVALID) { + if (lchown(path, uid, gid) < 0) + log_debug_errno(errno, "Failed to chown '%s': %m", path); + } + } + + return 0; +} |