diff options
Diffstat (limited to 'kernel/seccomp.c')
| -rw-r--r-- | kernel/seccomp.c | 119 |
1 files changed, 58 insertions, 61 deletions
diff --git a/kernel/seccomp.c b/kernel/seccomp.c index b7a10048a32c..4f18e754c23e 100644 --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -55,60 +55,33 @@ struct seccomp_filter { atomic_t usage; struct seccomp_filter *prev; unsigned short len; /* Instruction count */ - struct sock_filter insns[]; + struct sock_filter_int insnsi[]; }; /* Limit any path through the tree to 256KB worth of instructions. */ #define MAX_INSNS_PER_PATH ((1 << 18) / sizeof(struct sock_filter)) -/** - * get_u32 - returns a u32 offset into data - * @data: a unsigned 64 bit value - * @index: 0 or 1 to return the first or second 32-bits - * - * This inline exists to hide the length of unsigned long. If a 32-bit - * unsigned long is passed in, it will be extended and the top 32-bits will be - * 0. If it is a 64-bit unsigned long, then whatever data is resident will be - * properly returned. - * +/* * Endianness is explicitly ignored and left for BPF program authors to manage * as per the specific architecture. */ -static inline u32 get_u32(u64 data, int index) +static void populate_seccomp_data(struct seccomp_data *sd) { - return ((u32 *)&data)[index]; -} + struct task_struct *task = current; + struct pt_regs *regs = task_pt_regs(task); -/* Helper for bpf_load below. */ -#define BPF_DATA(_name) offsetof(struct seccomp_data, _name) -/** - * bpf_load: checks and returns a pointer to the requested offset - * @off: offset into struct seccomp_data to load from - * - * Returns the requested 32-bits of data. - * seccomp_check_filter() should assure that @off is 32-bit aligned - * and not out of bounds. Failure to do so is a BUG. - */ -u32 seccomp_bpf_load(int off) -{ - struct pt_regs *regs = task_pt_regs(current); - if (off == BPF_DATA(nr)) - return syscall_get_nr(current, regs); - if (off == BPF_DATA(arch)) - return syscall_get_arch(current, regs); - if (off >= BPF_DATA(args[0]) && off < BPF_DATA(args[6])) { - unsigned long value; - int arg = (off - BPF_DATA(args[0])) / sizeof(u64); - int index = !!(off % sizeof(u64)); - syscall_get_arguments(current, regs, arg, 1, &value); - return get_u32(value, index); - } - if (off == BPF_DATA(instruction_pointer)) - return get_u32(KSTK_EIP(current), 0); - if (off == BPF_DATA(instruction_pointer) + sizeof(u32)) - return get_u32(KSTK_EIP(current), 1); - /* seccomp_check_filter should make this impossible. */ - BUG(); + sd->nr = syscall_get_nr(task, regs); + sd->arch = syscall_get_arch(task, regs); + + /* Unroll syscall_get_args to help gcc on arm. */ + syscall_get_arguments(task, regs, 0, 1, (unsigned long *) &sd->args[0]); + syscall_get_arguments(task, regs, 1, 1, (unsigned long *) &sd->args[1]); + syscall_get_arguments(task, regs, 2, 1, (unsigned long *) &sd->args[2]); + syscall_get_arguments(task, regs, 3, 1, (unsigned long *) &sd->args[3]); + syscall_get_arguments(task, regs, 4, 1, (unsigned long *) &sd->args[4]); + syscall_get_arguments(task, regs, 5, 1, (unsigned long *) &sd->args[5]); + + sd->instruction_pointer = KSTK_EIP(task); } /** @@ -133,17 +106,17 @@ static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen) switch (code) { case BPF_S_LD_W_ABS: - ftest->code = BPF_S_ANC_SECCOMP_LD_W; + ftest->code = BPF_LDX | BPF_W | BPF_ABS; /* 32-bit aligned and not out of bounds. */ if (k >= sizeof(struct seccomp_data) || k & 3) return -EINVAL; continue; case BPF_S_LD_W_LEN: - ftest->code = BPF_S_LD_IMM; + ftest->code = BPF_LD | BPF_IMM; ftest->k = sizeof(struct seccomp_data); continue; case BPF_S_LDX_W_LEN: - ftest->code = BPF_S_LDX_IMM; + ftest->code = BPF_LDX | BPF_IMM; ftest->k = sizeof(struct seccomp_data); continue; /* Explicitly include allowed calls. */ @@ -185,6 +158,7 @@ static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen) case BPF_S_JMP_JGT_X: case BPF_S_JMP_JSET_K: case BPF_S_JMP_JSET_X: + sk_decode_filter(ftest, ftest); continue; default: return -EINVAL; @@ -202,18 +176,21 @@ static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen) static u32 seccomp_run_filters(int syscall) { struct seccomp_filter *f; + struct seccomp_data sd; u32 ret = SECCOMP_RET_ALLOW; /* Ensure unexpected behavior doesn't result in failing open. */ if (WARN_ON(current->seccomp.filter == NULL)) return SECCOMP_RET_KILL; + populate_seccomp_data(&sd); + /* * All filters in the list are evaluated and the lowest BPF return * value always takes priority (ignoring the DATA). */ for (f = current->seccomp.filter; f; f = f->prev) { - u32 cur_ret = sk_run_filter(NULL, f->insns); + u32 cur_ret = sk_run_filter_int_seccomp(&sd, f->insnsi); if ((cur_ret & SECCOMP_RET_ACTION) < (ret & SECCOMP_RET_ACTION)) ret = cur_ret; } @@ -231,6 +208,8 @@ static long seccomp_attach_filter(struct sock_fprog *fprog) struct seccomp_filter *filter; unsigned long fp_size = fprog->len * sizeof(struct sock_filter); unsigned long total_insns = fprog->len; + struct sock_filter *fp; + int new_len; long ret; if (fprog->len == 0 || fprog->len > BPF_MAXINSNS) @@ -252,28 +231,43 @@ static long seccomp_attach_filter(struct sock_fprog *fprog) CAP_SYS_ADMIN) != 0) return -EACCES; - /* Allocate a new seccomp_filter */ - filter = kzalloc(sizeof(struct seccomp_filter) + fp_size, - GFP_KERNEL|__GFP_NOWARN); - if (!filter) + fp = kzalloc(fp_size, GFP_KERNEL|__GFP_NOWARN); + if (!fp) return -ENOMEM; - atomic_set(&filter->usage, 1); - filter->len = fprog->len; /* Copy the instructions from fprog. */ ret = -EFAULT; - if (copy_from_user(filter->insns, fprog->filter, fp_size)) - goto fail; + if (copy_from_user(fp, fprog->filter, fp_size)) + goto free_prog; /* Check and rewrite the fprog via the skb checker */ - ret = sk_chk_filter(filter->insns, filter->len); + ret = sk_chk_filter(fp, fprog->len); if (ret) - goto fail; + goto free_prog; /* Check and rewrite the fprog for seccomp use */ - ret = seccomp_check_filter(filter->insns, filter->len); + ret = seccomp_check_filter(fp, fprog->len); + if (ret) + goto free_prog; + + /* Convert 'sock_filter' insns to 'sock_filter_int' insns */ + ret = sk_convert_filter(fp, fprog->len, NULL, &new_len); + if (ret) + goto free_prog; + + /* Allocate a new seccomp_filter */ + filter = kzalloc(sizeof(struct seccomp_filter) + + sizeof(struct sock_filter_int) * new_len, + GFP_KERNEL|__GFP_NOWARN); + if (!filter) + goto free_prog; + + ret = sk_convert_filter(fp, fprog->len, filter->insnsi, &new_len); if (ret) - goto fail; + goto free_filter; + + atomic_set(&filter->usage, 1); + filter->len = new_len; /* * If there is an existing filter, make it the prev and don't drop its @@ -282,8 +276,11 @@ static long seccomp_attach_filter(struct sock_fprog *fprog) filter->prev = current->seccomp.filter; current->seccomp.filter = filter; return 0; -fail: + +free_filter: kfree(filter); +free_prog: + kfree(fp); return ret; } |