aboutsummaryrefslogtreecommitdiff
path: root/kernel/seccomp.c
diff options
context:
space:
mode:
Diffstat (limited to 'kernel/seccomp.c')
-rw-r--r--kernel/seccomp.c224
1 files changed, 115 insertions, 109 deletions
diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index b7a10048a32..301bbc24739 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -39,7 +39,7 @@
* is only needed for handling filters shared across tasks.
* @prev: points to a previously installed, or inherited, filter
* @len: the number of instructions in the program
- * @insns: the BPF program instructions to evaluate
+ * @insnsi: the BPF program instructions to evaluate
*
* seccomp_filter objects are organized in a tree linked via the @prev
* pointer. For any task, it appears to be a singly-linked list starting
@@ -54,61 +54,32 @@
struct seccomp_filter {
atomic_t usage;
struct seccomp_filter *prev;
- unsigned short len; /* Instruction count */
- struct sock_filter insns[];
+ struct sk_filter *prog;
};
/* 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];
-}
-
-/* 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();
+ struct task_struct *task = current;
+ struct pt_regs *regs = task_pt_regs(task);
+ unsigned long args[6];
+
+ sd->nr = syscall_get_nr(task, regs);
+ sd->arch = syscall_get_arch();
+ syscall_get_arguments(task, regs, 0, 6, args);
+ sd->args[0] = args[0];
+ sd->args[1] = args[1];
+ sd->args[2] = args[2];
+ sd->args[3] = args[3];
+ sd->args[4] = args[4];
+ sd->args[5] = args[5];
+ sd->instruction_pointer = KSTK_EIP(task);
}
/**
@@ -132,59 +103,59 @@ static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen)
u32 k = ftest->k;
switch (code) {
- case BPF_S_LD_W_ABS:
- ftest->code = BPF_S_ANC_SECCOMP_LD_W;
+ case BPF_LD | BPF_W | BPF_ABS:
+ 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;
+ case BPF_LD | BPF_W | BPF_LEN:
+ 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;
+ case BPF_LDX | BPF_W | BPF_LEN:
+ ftest->code = BPF_LDX | BPF_IMM;
ftest->k = sizeof(struct seccomp_data);
continue;
/* Explicitly include allowed calls. */
- case BPF_S_RET_K:
- case BPF_S_RET_A:
- case BPF_S_ALU_ADD_K:
- case BPF_S_ALU_ADD_X:
- case BPF_S_ALU_SUB_K:
- case BPF_S_ALU_SUB_X:
- case BPF_S_ALU_MUL_K:
- case BPF_S_ALU_MUL_X:
- case BPF_S_ALU_DIV_X:
- case BPF_S_ALU_AND_K:
- case BPF_S_ALU_AND_X:
- case BPF_S_ALU_OR_K:
- case BPF_S_ALU_OR_X:
- case BPF_S_ALU_XOR_K:
- case BPF_S_ALU_XOR_X:
- case BPF_S_ALU_LSH_K:
- case BPF_S_ALU_LSH_X:
- case BPF_S_ALU_RSH_K:
- case BPF_S_ALU_RSH_X:
- case BPF_S_ALU_NEG:
- case BPF_S_LD_IMM:
- case BPF_S_LDX_IMM:
- case BPF_S_MISC_TAX:
- case BPF_S_MISC_TXA:
- case BPF_S_ALU_DIV_K:
- case BPF_S_LD_MEM:
- case BPF_S_LDX_MEM:
- case BPF_S_ST:
- case BPF_S_STX:
- case BPF_S_JMP_JA:
- case BPF_S_JMP_JEQ_K:
- case BPF_S_JMP_JEQ_X:
- case BPF_S_JMP_JGE_K:
- case BPF_S_JMP_JGE_X:
- case BPF_S_JMP_JGT_K:
- case BPF_S_JMP_JGT_X:
- case BPF_S_JMP_JSET_K:
- case BPF_S_JMP_JSET_X:
+ case BPF_RET | BPF_K:
+ case BPF_RET | BPF_A:
+ case BPF_ALU | BPF_ADD | BPF_K:
+ case BPF_ALU | BPF_ADD | BPF_X:
+ case BPF_ALU | BPF_SUB | BPF_K:
+ case BPF_ALU | BPF_SUB | BPF_X:
+ case BPF_ALU | BPF_MUL | BPF_K:
+ case BPF_ALU | BPF_MUL | BPF_X:
+ case BPF_ALU | BPF_DIV | BPF_K:
+ case BPF_ALU | BPF_DIV | BPF_X:
+ case BPF_ALU | BPF_AND | BPF_K:
+ case BPF_ALU | BPF_AND | BPF_X:
+ case BPF_ALU | BPF_OR | BPF_K:
+ case BPF_ALU | BPF_OR | BPF_X:
+ case BPF_ALU | BPF_XOR | BPF_K:
+ case BPF_ALU | BPF_XOR | BPF_X:
+ case BPF_ALU | BPF_LSH | BPF_K:
+ case BPF_ALU | BPF_LSH | BPF_X:
+ case BPF_ALU | BPF_RSH | BPF_K:
+ case BPF_ALU | BPF_RSH | BPF_X:
+ case BPF_ALU | BPF_NEG:
+ case BPF_LD | BPF_IMM:
+ case BPF_LDX | BPF_IMM:
+ case BPF_MISC | BPF_TAX:
+ case BPF_MISC | BPF_TXA:
+ case BPF_LD | BPF_MEM:
+ case BPF_LDX | BPF_MEM:
+ case BPF_ST:
+ case BPF_STX:
+ case BPF_JMP | BPF_JA:
+ case BPF_JMP | BPF_JEQ | BPF_K:
+ case BPF_JMP | BPF_JEQ | BPF_X:
+ case BPF_JMP | BPF_JGE | BPF_K:
+ case BPF_JMP | BPF_JGE | BPF_X:
+ case BPF_JMP | BPF_JGT | BPF_K:
+ case BPF_JMP | BPF_JGT | BPF_X:
+ case BPF_JMP | BPF_JSET | BPF_K:
+ case BPF_JMP | BPF_JSET | BPF_X:
continue;
default:
return -EINVAL;
@@ -202,18 +173,22 @@ 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(f->prog, (void *)&sd);
+
if ((cur_ret & SECCOMP_RET_ACTION) < (ret & SECCOMP_RET_ACTION))
ret = cur_ret;
}
@@ -231,18 +206,20 @@ 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)
return -EINVAL;
for (filter = current->seccomp.filter; filter; filter = filter->prev)
- total_insns += filter->len + 4; /* include a 4 instr penalty */
+ total_insns += filter->prog->len + 4; /* include a 4 instr penalty */
if (total_insns > MAX_INSNS_PER_PATH)
return -ENOMEM;
/*
- * Installing a seccomp filter requires that the task have
+ * Installing a seccomp filter requires that the task has
* CAP_SYS_ADMIN in its namespace or be running with no_new_privs.
* This avoids scenarios where unprivileged tasks can affect the
* behavior of privileged children.
@@ -252,28 +229,51 @@ 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 fail;
+ goto free_prog;
+
+ /* Allocate a new seccomp_filter */
+ ret = -ENOMEM;
+ filter = kzalloc(sizeof(struct seccomp_filter),
+ GFP_KERNEL|__GFP_NOWARN);
+ if (!filter)
+ goto free_prog;
+
+ filter->prog = kzalloc(sk_filter_size(new_len),
+ GFP_KERNEL|__GFP_NOWARN);
+ if (!filter->prog)
+ goto free_filter;
+
+ ret = sk_convert_filter(fp, fprog->len, filter->prog->insnsi, &new_len);
+ if (ret)
+ goto free_filter_prog;
+ kfree(fp);
+
+ atomic_set(&filter->usage, 1);
+ filter->prog->len = new_len;
+
+ sk_filter_select_runtime(filter->prog);
/*
* If there is an existing filter, make it the prev and don't drop its
@@ -282,8 +282,13 @@ static long seccomp_attach_filter(struct sock_fprog *fprog)
filter->prev = current->seccomp.filter;
current->seccomp.filter = filter;
return 0;
-fail:
+
+free_filter_prog:
+ kfree(filter->prog);
+free_filter:
kfree(filter);
+free_prog:
+ kfree(fp);
return ret;
}
@@ -293,7 +298,7 @@ fail:
*
* Returns 0 on success and non-zero otherwise.
*/
-long seccomp_attach_user_filter(char __user *user_filter)
+static long seccomp_attach_user_filter(char __user *user_filter)
{
struct sock_fprog fprog;
long ret = -EFAULT;
@@ -332,6 +337,7 @@ void put_seccomp_filter(struct task_struct *tsk)
while (orig && atomic_dec_and_test(&orig->usage)) {
struct seccomp_filter *freeme = orig;
orig = orig->prev;
+ sk_filter_free(freeme->prog);
kfree(freeme);
}
}
@@ -351,7 +357,7 @@ static void seccomp_send_sigsys(int syscall, int reason)
info.si_code = SYS_SECCOMP;
info.si_call_addr = (void __user *)KSTK_EIP(current);
info.si_errno = reason;
- info.si_arch = syscall_get_arch(current, task_pt_regs(current));
+ info.si_arch = syscall_get_arch();
info.si_syscall = syscall;
force_sig_info(SIGSYS, &info, current);
}
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2025-11-04 19:06:46 +0000