From d4dfd82835bb6f92de3bfb8a1cbf6beaf892ad08 Mon Sep 17 00:00:00 2001 From: Mark Salyzyn Date: Tue, 20 Dec 2016 15:59:19 -0800 Subject: android: fiq_debugger: restrict access to critical commands. Sysrq must be enabled via /proc/sys/kernel/sysrq as a security measure to enable various critical fiq debugger commands that either leak information or can be used as a system attack. Default disabled, this will leave the reboot, reset, irqs, sleep, nosleep, console and ps commands. Reboot and reset commands will be restricted from taking any parameters. We will also switch to showing the limited command set in this mode. Signed-off-by: Mark Salyzyn Bug: 32402555 Change-Id: I3f74b1ff5e4971d619bcb37a911fed68fbb538d5 [d-cagle@codeaurora.org: Resolve merge conflict] Git-repo: https://android.googlesource.com/kernel/msm Git-commit: 1031836c0895f1f5a05c25efec83bfa11aa08ca9 Signed-off-by: Dennis Cagle --- .../staging/android/fiq_debugger/fiq_debugger.c | 86 ++++++++++++++-------- drivers/tty/sysrq.c | 3 +- include/linux/sysrq.h | 1 + 3 files changed, 57 insertions(+), 33 deletions(-) diff --git a/drivers/staging/android/fiq_debugger/fiq_debugger.c b/drivers/staging/android/fiq_debugger/fiq_debugger.c index 7d6b4ae..ceb45bc9e 100644 --- a/drivers/staging/android/fiq_debugger/fiq_debugger.c +++ b/drivers/staging/android/fiq_debugger/fiq_debugger.c @@ -30,6 +30,7 @@ #include #include #include +#include #include #include #include @@ -395,7 +396,7 @@ static void fiq_debugger_work(struct work_struct *work) cmd += 6; while (*cmd == ' ') cmd++; - if (cmd != '\0') + if ((cmd != '\0') && sysrq_on()) kernel_restart(cmd); else kernel_restart(NULL); @@ -425,29 +426,39 @@ static void fiq_debugger_irq_exec(struct fiq_debugger_state *state, char *cmd) static void fiq_debugger_help(struct fiq_debugger_state *state) { fiq_debugger_printf(&state->output, - "FIQ Debugger commands:\n" - " pc PC status\n" - " regs Register dump\n" - " allregs Extended Register dump\n" - " bt Stack trace\n" - " reboot [] Reboot with command \n" - " reset [] Hard reset with command \n" - " irqs Interupt status\n" - " kmsg Kernel log\n" - " version Kernel version\n"); - fiq_debugger_printf(&state->output, - " sleep Allow sleep while in FIQ\n" - " nosleep Disable sleep while in FIQ\n" - " console Switch terminal to console\n" - " cpu Current CPU\n" - " cpu Switch to CPU\n"); + "FIQ Debugger commands:\n"); + if (sysrq_on()) { + fiq_debugger_printf(&state->output, + " pc PC status\n" + " regs Register dump\n" + " allregs Extended Register dump\n" + " bt Stack trace\n"); + fiq_debugger_printf(&state->output, + " reboot [] Reboot with command \n" + " reset [] Hard reset with command \n" + " irqs Interrupt status\n" + " kmsg Kernel log\n" + " version Kernel version\n"); + fiq_debugger_printf(&state->output, + " cpu Current CPU\n" + " cpu Switch to CPU\n" + " sysrq sysrq options\n" + " sysrq Execute sysrq with \n"); + } else { + fiq_debugger_printf(&state->output, + " reboot Reboot\n" + " reset Hard reset\n" + " irqs Interrupt status\n"); + } fiq_debugger_printf(&state->output, - " ps Process list\n" - " sysrq sysrq options\n" - " sysrq Execute sysrq with \n"); + " sleep Allow sleep while in FIQ\n" + " nosleep Disable sleep while in FIQ\n" + " console Switch terminal to console\n" + " ps Process list\n"); #ifdef CONFIG_KGDB - fiq_debugger_printf(&state->output, - " kgdb Enter kernel debugger\n"); + if (fiq_kgdb_enable) { + fiq_debugger_printf(&state->output, + " kgdb Enter kernel debugger\n"); #endif } @@ -479,18 +490,23 @@ static bool fiq_debugger_fiq_exec(struct fiq_debugger_state *state, if (!strcmp(cmd, "help") || !strcmp(cmd, "?")) { fiq_debugger_help(state); } else if (!strcmp(cmd, "pc")) { - fiq_debugger_dump_pc(&state->output, regs); + if (sysrq_on()) + fiq_debugger_dump_pc(&state->output, regs); } else if (!strcmp(cmd, "regs")) { - fiq_debugger_dump_regs(&state->output, regs); + if (sysrq_on()) + fiq_debugger_dump_regs(&state->output, regs); } else if (!strcmp(cmd, "allregs")) { - fiq_debugger_dump_allregs(&state->output, regs); + if (sysrq_on()) + fiq_debugger_dump_allregs(&state->output, regs); } else if (!strcmp(cmd, "bt")) { - fiq_debugger_dump_stacktrace(&state->output, regs, 100, svc_sp); + if (sysrq_on()) + fiq_debugger_dump_stacktrace(&state->output, regs, + 100, svc_sp); } else if (!strncmp(cmd, "reset", 5)) { cmd += 5; while (*cmd == ' ') cmd++; - if (*cmd) { + if (*cmd && sysrq_on()) { char tmp_cmd[32]; strlcpy(tmp_cmd, cmd, sizeof(tmp_cmd)); machine_restart(tmp_cmd); @@ -500,9 +516,12 @@ static bool fiq_debugger_fiq_exec(struct fiq_debugger_state *state, } else if (!strcmp(cmd, "irqs")) { fiq_debugger_dump_irqs(state); } else if (!strcmp(cmd, "kmsg")) { - fiq_debugger_dump_kernel_log(state); + if (sysrq_on()) + fiq_debugger_dump_kernel_log(state); } else if (!strcmp(cmd, "version")) { - fiq_debugger_printf(&state->output, "%s\n", linux_banner); + if (sysrq_on()) + fiq_debugger_printf(&state->output, "%s\n", + linux_banner); } else if (!strcmp(cmd, "sleep")) { state->no_sleep = false; fiq_debugger_printf(&state->output, "enabling sleep\n"); @@ -514,14 +533,17 @@ static bool fiq_debugger_fiq_exec(struct fiq_debugger_state *state, fiq_debugger_uart_flush(state); state->console_enable = true; } else if (!strcmp(cmd, "cpu")) { - fiq_debugger_printf(&state->output, "cpu %d\n", state->current_cpu); - } else if (!strncmp(cmd, "cpu ", 4)) { + if (sysrq_on()) + fiq_debugger_printf(&state->output, "cpu %d\n", + state->current_cpu); + } else if (!strncmp(cmd, "cpu ", 4) && sysrq_on()) { unsigned long cpu = 0; if (strict_strtoul(cmd + 4, 10, &cpu) == 0) fiq_debugger_switch_cpu(state, cpu); else fiq_debugger_printf(&state->output, "invalid cpu\n"); - fiq_debugger_printf(&state->output, "cpu %d\n", state->current_cpu); + fiq_debugger_printf(&state->output, "cpu %d\n", + state->current_cpu); } else { if (state->debug_busy) { fiq_debugger_printf(&state->output, diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c index b51c154..08c9406 100644 --- a/drivers/tty/sysrq.c +++ b/drivers/tty/sysrq.c @@ -55,10 +55,11 @@ static bool __read_mostly sysrq_always_enabled; unsigned short platform_sysrq_reset_seq[] __weak = { KEY_RESERVED }; int sysrq_reset_downtime_ms __weak; -static bool sysrq_on(void) +bool sysrq_on(void) { return sysrq_enabled || sysrq_always_enabled; } +EXPORT_SYMBOL(sysrq_on); /* * A value of 1 means 'all', other nonzero values are an op mask: diff --git a/include/linux/sysrq.h b/include/linux/sysrq.h index 7faf933..5a0bd93 100644 --- a/include/linux/sysrq.h +++ b/include/linux/sysrq.h @@ -45,6 +45,7 @@ struct sysrq_key_op { * are available -- else NULL's). */ +bool sysrq_on(void); void handle_sysrq(int key); void __handle_sysrq(int key, bool check_mask); int register_sysrq_key(int key, struct sysrq_key_op *op); -- cgit v1.1