From efeb864cb547a2cbf96dc0053a8bdb4d9190b364 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Wed, 12 Jun 2024 05:50:45 +0200 Subject: Merging upstream version 256. Signed-off-by: Daniel Baumann --- src/basic/uid-classification.c | 131 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 131 insertions(+) create mode 100644 src/basic/uid-classification.c (limited to 'src/basic/uid-classification.c') diff --git a/src/basic/uid-classification.c b/src/basic/uid-classification.c new file mode 100644 index 0000000..e2d2ceb --- /dev/null +++ b/src/basic/uid-classification.c @@ -0,0 +1,131 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ + +#include "chase.h" +#include "fd-util.h" +#include "fileio.h" +#include "missing_threads.h" +#include "string-util.h" +#include "uid-classification.h" +#include "user-util.h" + +static const UGIDAllocationRange default_ugid_allocation_range = { + .system_alloc_uid_min = SYSTEM_ALLOC_UID_MIN, + .system_uid_max = SYSTEM_UID_MAX, + .system_alloc_gid_min = SYSTEM_ALLOC_GID_MIN, + .system_gid_max = SYSTEM_GID_MAX, +}; + +#if ENABLE_COMPAT_MUTABLE_UID_BOUNDARIES +static int parse_alloc_uid(const char *path, const char *name, const char *t, uid_t *ret_uid) { + uid_t uid; + int r; + + r = parse_uid(t, &uid); + if (r < 0) + return log_debug_errno(r, "%s: failed to parse %s %s, ignoring: %m", path, name, t); + if (uid == 0) + uid = 1; + + *ret_uid = uid; + return 0; +} +#endif + +int read_login_defs(UGIDAllocationRange *ret_defs, const char *path, const char *root) { +#if ENABLE_COMPAT_MUTABLE_UID_BOUNDARIES + _cleanup_fclose_ FILE *f = NULL; + UGIDAllocationRange defs; + int r; + + if (!path) + path = "/etc/login.defs"; + + r = chase_and_fopen_unlocked(path, root, CHASE_PREFIX_ROOT, "re", NULL, &f); + if (r == -ENOENT) + goto defaults; + if (r < 0) + return log_debug_errno(r, "Failed to open %s: %m", path); + + defs = default_ugid_allocation_range; + + for (;;) { + _cleanup_free_ char *line = NULL; + char *t; + + r = read_line(f, LINE_MAX, &line); + if (r < 0) + return log_debug_errno(r, "Failed to read %s: %m", path); + if (r == 0) + break; + + if ((t = first_word(line, "SYS_UID_MIN"))) + (void) parse_alloc_uid(path, "SYS_UID_MIN", t, &defs.system_alloc_uid_min); + else if ((t = first_word(line, "SYS_UID_MAX"))) + (void) parse_alloc_uid(path, "SYS_UID_MAX", t, &defs.system_uid_max); + else if ((t = first_word(line, "SYS_GID_MIN"))) + (void) parse_alloc_uid(path, "SYS_GID_MIN", t, &defs.system_alloc_gid_min); + else if ((t = first_word(line, "SYS_GID_MAX"))) + (void) parse_alloc_uid(path, "SYS_GID_MAX", t, &defs.system_gid_max); + } + + if (defs.system_alloc_uid_min > defs.system_uid_max) { + log_debug("%s: SYS_UID_MIN > SYS_UID_MAX, resetting.", path); + defs.system_alloc_uid_min = MIN(defs.system_uid_max - 1, (uid_t) SYSTEM_ALLOC_UID_MIN); + /* Look at sys_uid_max to make sure sys_uid_min..sys_uid_max remains a valid range. */ + } + if (defs.system_alloc_gid_min > defs.system_gid_max) { + log_debug("%s: SYS_GID_MIN > SYS_GID_MAX, resetting.", path); + defs.system_alloc_gid_min = MIN(defs.system_gid_max - 1, (gid_t) SYSTEM_ALLOC_GID_MIN); + /* Look at sys_gid_max to make sure sys_gid_min..sys_gid_max remains a valid range. */ + } + + *ret_defs = defs; + return 1; +defaults: +#endif + *ret_defs = default_ugid_allocation_range; + return 0; +} + +const UGIDAllocationRange *acquire_ugid_allocation_range(void) { +#if ENABLE_COMPAT_MUTABLE_UID_BOUNDARIES + static thread_local UGIDAllocationRange defs; + static thread_local int initialized = 0; /* == 0 → not initialized yet + * < 0 → failure + * > 0 → success */ + + /* This function will ignore failure to read the file, so it should only be called from places where + * we don't crucially depend on the answer. In other words, it's appropriate for journald, but + * probably not for sysusers. */ + + if (initialized == 0) + initialized = read_login_defs(&defs, NULL, NULL) < 0 ? -1 : 1; + if (initialized < 0) + return &default_ugid_allocation_range; + + return &defs; + +#endif + return &default_ugid_allocation_range; +} + +bool uid_is_system(uid_t uid) { + const UGIDAllocationRange *defs; + assert_se(defs = acquire_ugid_allocation_range()); + + return uid <= defs->system_uid_max; +} + +bool gid_is_system(gid_t gid) { + const UGIDAllocationRange *defs; + assert_se(defs = acquire_ugid_allocation_range()); + + return gid <= defs->system_gid_max; +} + +bool uid_for_system_journal(uid_t uid) { + + /* Returns true if the specified UID shall get its data stored in the system journal. */ + + return uid_is_system(uid) || uid_is_dynamic(uid) || uid == UID_NOBODY || uid_is_container(uid); +} -- cgit v1.2.3