From 858259cf7d1c443c836a2022b78cb281f0a9b95e Mon Sep 17 00:00:00 2001 From: Bodo Stroesser Date: Mon, 7 Nov 2005 00:58:55 -0800 Subject: [PATCH] uml: maintain own LDT entries Patch imlements full LDT handling in SKAS: * UML holds it's own LDT table, used to deliver data on modify_ldt(READ) * UML disables the default_ldt, inherited from the host (SKAS3) or resets LDT entries, set by host's clib and inherited in SKAS0 * A new global variable skas_needs_stub is inserted, that can be used to decide, whether stub-pages must be supported or not. * Uses the syscall-stub to replace missing PTRACE_LDT (therefore, write_ldt_entry needs to be modified) Signed-off-by: Bodo Stroesser Signed-off-by: Jeff Dike Cc: Paolo Giarrusso Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/um/os-Linux/start_up.c | 75 ++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 70 insertions(+), 5 deletions(-) (limited to 'arch/um/os-Linux/start_up.c') diff --git a/arch/um/os-Linux/start_up.c b/arch/um/os-Linux/start_up.c index b99ab414542f..553a09c7d0bc 100644 --- a/arch/um/os-Linux/start_up.c +++ b/arch/um/os-Linux/start_up.c @@ -135,7 +135,9 @@ static int stop_ptraced_child(int pid, void *stack, int exitcode, } int ptrace_faultinfo = 1; +int ptrace_ldt = 1; int proc_mm = 1; +int skas_needs_stub = 0; static int __init skas0_cmd_param(char *str, int* add) { @@ -352,14 +354,26 @@ __uml_setup("noptracefaultinfo", noptracefaultinfo_cmd_param, " it. To support PTRACE_FAULTINFO, the host needs to be patched\n" " using the current skas3 patch.\n\n"); +static int __init noptraceldt_cmd_param(char *str, int* add) +{ + ptrace_ldt = 0; + return 0; +} + +__uml_setup("noptraceldt", noptraceldt_cmd_param, +"noptraceldt\n" +" Turns off usage of PTRACE_LDT, even if host supports it.\n" +" To support PTRACE_LDT, the host needs to be patched using\n" +" the current skas3 patch.\n\n"); + #ifdef UML_CONFIG_MODE_SKAS -static inline void check_skas3_ptrace_support(void) +static inline void check_skas3_ptrace_faultinfo(void) { struct ptrace_faultinfo fi; void *stack; int pid, n; - printf("Checking for the skas3 patch in the host..."); + printf(" - PTRACE_FAULTINFO..."); pid = start_ptraced_child(&stack); n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi); @@ -381,9 +395,49 @@ static inline void check_skas3_ptrace_support(void) stop_ptraced_child(pid, stack, 1, 1); } -int can_do_skas(void) +static inline void check_skas3_ptrace_ldt(void) +{ +#ifdef PTRACE_LDT + void *stack; + int pid, n; + unsigned char ldtbuf[40]; + struct ptrace_ldt ldt_op = (struct ptrace_ldt) { + .func = 2, /* read default ldt */ + .ptr = ldtbuf, + .bytecount = sizeof(ldtbuf)}; + + printf(" - PTRACE_LDT..."); + pid = start_ptraced_child(&stack); + + n = ptrace(PTRACE_LDT, pid, 0, (unsigned long) &ldt_op); + if (n < 0) { + if(errno == EIO) + printf("not found\n"); + else { + perror("not found"); + } + ptrace_ldt = 0; + } + else { + if(ptrace_ldt) + printf("found\n"); + else + printf("found, but use is disabled\n"); + } + + stop_ptraced_child(pid, stack, 1, 1); +#else + /* PTRACE_LDT might be disabled via cmdline option. + * We want to override this, else we might use the stub + * without real need + */ + ptrace_ldt = 1; +#endif +} + +static inline void check_skas3_proc_mm(void) { - printf("Checking for /proc/mm..."); + printf(" - /proc/mm..."); if (os_access("/proc/mm", OS_ACC_W_OK) < 0) { proc_mm = 0; printf("not found\n"); @@ -394,8 +448,19 @@ int can_do_skas(void) else printf("found\n"); } +} + +int can_do_skas(void) +{ + printf("Checking for the skas3 patch in the host:\n"); + + check_skas3_proc_mm(); + check_skas3_ptrace_faultinfo(); + check_skas3_ptrace_ldt(); + + if(!proc_mm || !ptrace_faultinfo || !ptrace_ldt) + skas_needs_stub = 1; - check_skas3_ptrace_support(); return 1; } #else -- cgit v1.2.3