diff options
| -rw-r--r-- | src/basic/capability-util.c | 3 | ||||
| -rw-r--r-- | src/basic/user-util.c | 27 | ||||
| -rw-r--r-- | src/basic/user-util.h | 2 | ||||
| -rw-r--r-- | src/core/execute.c | 2 |
4 files changed, 31 insertions, 3 deletions
diff --git a/src/basic/capability-util.c b/src/basic/capability-util.c index d4c5bd6937..f8db6e0212 100644 --- a/src/basic/capability-util.c +++ b/src/basic/capability-util.c @@ -31,6 +31,7 @@ #include "log.h" #include "macro.h" #include "parse-util.h" +#include "user-util.h" #include "util.h" int have_effective_cap(int value) { @@ -295,7 +296,7 @@ int drop_privileges(uid_t uid, gid_t gid, uint64_t keep_capabilities) { if (setresgid(gid, gid, gid) < 0) return log_error_errno(errno, "Failed to change group ID: %m"); - if (setgroups(0, NULL) < 0) + if (maybe_setgroups(0, NULL) < 0) return log_error_errno(errno, "Failed to drop auxiliary groups list: %m"); /* Ensure we keep the permitted caps across the setresuid() */ diff --git a/src/basic/user-util.c b/src/basic/user-util.c index 0522bce1d1..16496fccfa 100644 --- a/src/basic/user-util.c +++ b/src/basic/user-util.c @@ -33,6 +33,7 @@ #include "alloc-util.h" #include "fd-util.h" +#include "fileio.h" #include "formats-util.h" #include "macro.h" #include "missing.h" @@ -460,7 +461,7 @@ int get_shell(char **_s) { int reset_uid_gid(void) { - if (setgroups(0, NULL) < 0) + if (maybe_setgroups(0, NULL) < 0) return -errno; if (setresgid(0, 0, 0) < 0) @@ -602,3 +603,27 @@ bool valid_home(const char *p) { return true; } + +int maybe_setgroups(size_t size, const gid_t *list) { + static int cached_can_setgroups = -1; + /* check if setgroups is allowed before we try to drop all the auxiliary groups */ + if (size == 0) { + if (cached_can_setgroups < 0) { + _cleanup_free_ char *setgroups_content = NULL; + int r = read_one_line_file("/proc/self/setgroups", &setgroups_content); + if (r < 0 && errno != ENOENT) + return r; + if (r < 0) { + /* old kernels don't have /proc/self/setgroups, so assume we can use setgroups */ + cached_can_setgroups = true; + } else { + cached_can_setgroups = streq(setgroups_content, "allow"); + if (!cached_can_setgroups) + log_debug("skip setgroups, /proc/self/setgroups is set to 'deny'"); + } + } + if (!cached_can_setgroups) + return 0; + } + return setgroups(size, list); +} diff --git a/src/basic/user-util.h b/src/basic/user-util.h index 6c61f63cae..dfea561bde 100644 --- a/src/basic/user-util.h +++ b/src/basic/user-util.h @@ -86,3 +86,5 @@ bool valid_user_group_name(const char *u); bool valid_user_group_name_or_id(const char *u); bool valid_gecos(const char *d); bool valid_home(const char *p); + +int maybe_setgroups(size_t size, const gid_t *list); diff --git a/src/core/execute.c b/src/core/execute.c index 82d8c978c1..019ff8490b 100644 --- a/src/core/execute.c +++ b/src/core/execute.c @@ -781,7 +781,7 @@ static int enforce_groups(const ExecContext *context, const char *username, gid_ k++; } - if (setgroups(k, gids) < 0) { + if (maybe_setgroups(k, gids) < 0) { free(gids); return -errno; } |