diff options
author | Chris Metcalf <cmetcalf@tilera.com> | 2010-10-28 23:47:06 +0400 |
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committer | Chris Metcalf <cmetcalf@tilera.com> | 2010-11-01 22:31:17 +0300 |
commit | 1deb9c5dfb179819ecdbf80a1d121e26c63caab3 (patch) | |
tree | c6f6ec6030eb22f094a65c07e63312758d079794 /arch/tile/kernel/ptrace.c | |
parent | 34a89d26bdc4ba46a406fa3842239e921c493d44 (diff) | |
download | linux-1deb9c5dfb179819ecdbf80a1d121e26c63caab3.tar.xz |
arch/tile: don't allow user code to set the PL via ptrace or signal return
The kernel was allowing any component of the pt_regs to be updated either
by signal handlers writing to the stack, or by processes writing via
PTRACE_POKEUSR or PTRACE_SETREGS, which meant they could set their PL
up from 0 to 1 and get access to kernel code and data (or, in practice,
cause a kernel panic). We now always reset the ex1 field, allowing the
user to set their ICS bit only.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Diffstat (limited to 'arch/tile/kernel/ptrace.c')
-rw-r--r-- | arch/tile/kernel/ptrace.c | 39 |
1 files changed, 21 insertions, 18 deletions
diff --git a/arch/tile/kernel/ptrace.c b/arch/tile/kernel/ptrace.c index 9cd29884c09f..e92e40527d6d 100644 --- a/arch/tile/kernel/ptrace.c +++ b/arch/tile/kernel/ptrace.c @@ -50,10 +50,10 @@ long arch_ptrace(struct task_struct *child, long request, { unsigned long __user *datap = (long __user __force *)data; unsigned long tmp; - int i; long ret = -EIO; - unsigned long *childregs; char *childreg; + struct pt_regs copyregs; + int ex1_offset; switch (request) { @@ -80,6 +80,16 @@ long arch_ptrace(struct task_struct *child, long request, if (addr >= PTREGS_SIZE) break; childreg = (char *)task_pt_regs(child) + addr; + + /* Guard against overwrites of the privilege level. */ + ex1_offset = PTREGS_OFFSET_EX1; +#if defined(CONFIG_COMPAT) && defined(__BIG_ENDIAN) + if (is_compat_task()) /* point at low word */ + ex1_offset += sizeof(compat_long_t); +#endif + if (addr == ex1_offset) + data = PL_ICS_EX1(USER_PL, EX1_ICS(data)); + #ifdef CONFIG_COMPAT if (is_compat_task()) { if (addr & (sizeof(compat_long_t)-1)) @@ -96,26 +106,19 @@ long arch_ptrace(struct task_struct *child, long request, break; case PTRACE_GETREGS: /* Get all registers from the child. */ - if (!access_ok(VERIFY_WRITE, datap, PTREGS_SIZE)) - break; - childregs = (long *)task_pt_regs(child); - for (i = 0; i < sizeof(struct pt_regs)/sizeof(unsigned long); - ++i) { - ret = __put_user(childregs[i], &datap[i]); - if (ret != 0) - break; + if (copy_to_user(datap, task_pt_regs(child), + sizeof(struct pt_regs)) == 0) { + ret = 0; } break; case PTRACE_SETREGS: /* Set all registers in the child. */ - if (!access_ok(VERIFY_READ, datap, PTREGS_SIZE)) - break; - childregs = (long *)task_pt_regs(child); - for (i = 0; i < sizeof(struct pt_regs)/sizeof(unsigned long); - ++i) { - ret = __get_user(childregs[i], &datap[i]); - if (ret != 0) - break; + if (copy_from_user(©regs, datap, + sizeof(struct pt_regs)) == 0) { + copyregs.ex1 = + PL_ICS_EX1(USER_PL, EX1_ICS(copyregs.ex1)); + *task_pt_regs(child) = copyregs; + ret = 0; } break; |