From: Nicolai Hähnle <[email protected]> Having different types of code all trying to check for elevated privileges is a bad idea. This implementation is the most thorough one.
Signed-off-by: Nicolai Hähnle <[email protected]> --- hw/xfree86/common/xf86Init.c | 59 +---------------------------------------- include/os.h | 3 +++ os/utils.c | 63 ++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 67 insertions(+), 58 deletions(-) diff --git a/hw/xfree86/common/xf86Init.c b/hw/xfree86/common/xf86Init.c index e61fe66..758b926 100644 --- a/hw/xfree86/common/xf86Init.c +++ b/hw/xfree86/common/xf86Init.c @@ -230,78 +230,21 @@ xf86PrintBanner(void) xf86ErrorFVerb(0, "Current version of pixman: %s\n", pixman_version_string()); xf86ErrorFVerb(0, "\tBefore reporting problems, check " "" __VENDORDWEBSUPPORT__ "\n" "\tto make sure that you have the latest version.\n"); } Bool xf86PrivsElevated(void) { - static Bool privsTested = FALSE; - static Bool privsElevated = TRUE; - - if (!privsTested) { -#if defined(WIN32) - privsElevated = FALSE; -#else - if ((getuid() != geteuid()) || (getgid() != getegid())) { - privsElevated = TRUE; - } - else { -#if defined(HAVE_ISSETUGID) - privsElevated = issetugid(); -#elif defined(HAVE_GETRESUID) - uid_t ruid, euid, suid; - gid_t rgid, egid, sgid; - - if ((getresuid(&ruid, &euid, &suid) == 0) && - (getresgid(&rgid, &egid, &sgid) == 0)) { - privsElevated = (euid != suid) || (egid != sgid); - } - else { - printf("Failed getresuid or getresgid"); - /* Something went wrong, make defensive assumption */ - privsElevated = TRUE; - } -#else - if (getuid() == 0) { - /* running as root: uid==euid==0 */ - privsElevated = FALSE; - } - else { - /* - * If there are saved ID's the process might still be privileged - * even though the above test succeeded. If issetugid() and - * getresgid() aren't available, test this by trying to set - * euid to 0. - */ - unsigned int oldeuid; - - oldeuid = geteuid(); - - if (seteuid(0) != 0) { - privsElevated = FALSE; - } - else { - if (seteuid(oldeuid) != 0) { - FatalError("Failed to drop privileges. Exiting\n"); - } - privsElevated = TRUE; - } - } -#endif - } -#endif - privsTested = TRUE; - } - return privsElevated; + return PrivsElevated(); } static void InstallSignalHandlers(void) { /* * Install signal handler for unexpected signals */ xf86Info.caughtSignal = FALSE; if (!xf86Info.notrapSignals) { diff --git a/include/os.h b/include/os.h index d2c41b4..686f6d6 100644 --- a/include/os.h +++ b/include/os.h @@ -355,20 +355,23 @@ Fclose(void *); extern const char * Win32TempDir(void); extern int System(const char *cmdline); #define Fopen(a,b) fopen(a,b) #define Fclose(a) fclose(a) #endif +extern _X_EXPORT Bool +PrivsElevated(void); + extern _X_EXPORT void CheckUserParameters(int argc, char **argv, char **envp); extern _X_EXPORT void CheckUserAuthorization(void); extern _X_EXPORT int AddHost(ClientPtr /*client */ , int /*family */ , unsigned /*length */ , const void * /*pAddr */ ); diff --git a/os/utils.c b/os/utils.c index ac55cd7..024989e 100644 --- a/os/utils.c +++ b/os/utils.c @@ -1717,20 +1717,83 @@ System(const char *cmdline) /* Close process and thread handles. */ CloseHandle(pi.hProcess); CloseHandle(pi.hThread); free(cmd); return dwExitCode; } #endif +Bool +PrivsElevated(void) +{ + static Bool privsTested = FALSE; + static Bool privsElevated = TRUE; + + if (!privsTested) { +#if defined(WIN32) + privsElevated = FALSE; +#else + if ((getuid() != geteuid()) || (getgid() != getegid())) { + privsElevated = TRUE; + } + else { +#if defined(HAVE_ISSETUGID) + privsElevated = issetugid(); +#elif defined(HAVE_GETRESUID) + uid_t ruid, euid, suid; + gid_t rgid, egid, sgid; + + if ((getresuid(&ruid, &euid, &suid) == 0) && + (getresgid(&rgid, &egid, &sgid) == 0)) { + privsElevated = (euid != suid) || (egid != sgid); + } + else { + printf("Failed getresuid or getresgid"); + /* Something went wrong, make defensive assumption */ + privsElevated = TRUE; + } +#else + if (getuid() == 0) { + /* running as root: uid==euid==0 */ + privsElevated = FALSE; + } + else { + /* + * If there are saved ID's the process might still be privileged + * even though the above test succeeded. If issetugid() and + * getresgid() aren't available, test this by trying to set + * euid to 0. + */ + unsigned int oldeuid; + + oldeuid = geteuid(); + + if (seteuid(0) != 0) { + privsElevated = FALSE; + } + else { + if (seteuid(oldeuid) != 0) { + FatalError("Failed to drop privileges. Exiting\n"); + } + privsElevated = TRUE; + } + } +#endif + } +#endif + privsTested = TRUE; + } + return privsElevated; +} + /* * CheckUserParameters: check for long command line arguments and long * environment variables. By default, these checks are only done when * the server's euid != ruid. In 3.3.x, these checks were done in an * external wrapper utility. */ /* Consider LD* variables insecure? */ #ifndef REMOVE_ENV_LD #define REMOVE_ENV_LD 1 -- 2.7.4 _______________________________________________ [email protected]: X.Org development Archives: http://lists.x.org/archives/xorg-devel Info: https://lists.x.org/mailman/listinfo/xorg-devel
