diff options
Diffstat (limited to 'fs/proc/base.c')
| -rw-r--r-- | fs/proc/base.c | 65 |
1 files changed, 62 insertions, 3 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c index 7f3abc3de49f..1ad51858528f 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -85,6 +85,7 @@ #include <linux/elf.h> #include <linux/pid_namespace.h> #include <linux/user_namespace.h> +#include <linux/fs_parser.h> #include <linux/fs_struct.h> #include <linux/slab.h> #include <linux/sched/autogroup.h> @@ -117,6 +118,40 @@ static u8 nlink_tid __ro_after_init; static u8 nlink_tgid __ro_after_init; +enum proc_mem_force { + PROC_MEM_FORCE_ALWAYS, + PROC_MEM_FORCE_PTRACE, + PROC_MEM_FORCE_NEVER +}; + +static enum proc_mem_force proc_mem_force_override __ro_after_init = + IS_ENABLED(CONFIG_PROC_MEM_NO_FORCE) ? PROC_MEM_FORCE_NEVER : + IS_ENABLED(CONFIG_PROC_MEM_FORCE_PTRACE) ? PROC_MEM_FORCE_PTRACE : + PROC_MEM_FORCE_ALWAYS; + +static const struct constant_table proc_mem_force_table[] __initconst = { + { "always", PROC_MEM_FORCE_ALWAYS }, + { "ptrace", PROC_MEM_FORCE_PTRACE }, + { "never", PROC_MEM_FORCE_NEVER }, + { } +}; + +static int __init early_proc_mem_force_override(char *buf) +{ + if (!buf) + return -EINVAL; + + /* + * lookup_constant() defaults to proc_mem_force_override to preseve + * the initial Kconfig choice in case an invalid param gets passed. + */ + proc_mem_force_override = lookup_constant(proc_mem_force_table, + buf, proc_mem_force_override); + + return 0; +} +early_param("proc_mem.force_override", early_proc_mem_force_override); + struct pid_entry { const char *name; unsigned int len; @@ -832,6 +867,28 @@ static int mem_open(struct inode *inode, struct file *file) return __mem_open(inode, file, PTRACE_MODE_ATTACH); } +static bool proc_mem_foll_force(struct file *file, struct mm_struct *mm) +{ + struct task_struct *task; + bool ptrace_active = false; + + switch (proc_mem_force_override) { + case PROC_MEM_FORCE_NEVER: + return false; + case PROC_MEM_FORCE_PTRACE: + task = get_proc_task(file_inode(file)); + if (task) { + ptrace_active = READ_ONCE(task->ptrace) && + READ_ONCE(task->mm) == mm && + READ_ONCE(task->parent) == current; + put_task_struct(task); + } + return ptrace_active; + default: + return true; + } +} + static ssize_t mem_rw(struct file *file, char __user *buf, size_t count, loff_t *ppos, int write) { @@ -852,7 +909,9 @@ static ssize_t mem_rw(struct file *file, char __user *buf, if (!mmget_not_zero(mm)) goto free; - flags = FOLL_FORCE | (write ? FOLL_WRITE : 0); + flags = write ? FOLL_WRITE : 0; + if (proc_mem_foll_force(file, mm)) + flags |= FOLL_FORCE; while (count > 0) { size_t this_len = min_t(size_t, count, PAGE_SIZE); @@ -2274,8 +2333,8 @@ proc_map_files_instantiate(struct dentry *dentry, inode->i_op = &proc_map_files_link_inode_operations; inode->i_size = 64; - d_set_d_op(dentry, &tid_map_files_dentry_operations); - return d_splice_alias(inode, dentry); + return proc_splice_unmountable(inode, dentry, + &tid_map_files_dentry_operations); } static struct dentry *proc_map_files_lookup(struct inode *dir, |