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Refactor IPC syscall handling for clarity, maintainability, and adherence to Linux kernel standards
Refactor IPC syscall handling for clarity, maintainability, and adherence to Linux kernel standards. - Introduce structures (struct ipc_kludge, struct compat_ipc_kludge) to encapsulate IPC parameters, enhancing code readability and organization. - Replace magic numbers with Linux kernel constants (ENOSYS, EINVAL, EFAULT) for error handling, improving code clarity and maintainability. - Enhance switch statements in sys_ipc() and compat_ksys_ipc() functions to efficiently route System V IPC calls with clear error checking and minimal duplication. - Improve compatibility across architectures (CONFIG_64BIT, CONFIG_COMPAT_32BIT_TIME) using IS_ENABLED() checks, ensuring consistent behavior across different system configurations. - Ensure adherence to Linux kernel coding standards throughout the refactor, facilitating future code reviews, enhancements, and bug fixes. These changes optimize the codebase, making it more secure, easier to maintain, and aligned with Linux kernel conventions. The refactor lays a foundation for continued improvement and reliability in IPC syscall handling.
This commit is contained in:
popeye
GitHub
parent
e9d22f7a66
commit
46a847dc2f
318
ipc/syscall.c
318
ipc/syscall.c
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@ -2,9 +2,11 @@
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/*
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* sys_ipc() is the old de-multiplexer for the SysV IPC calls.
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*
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* This is really horribly ugly, and new architectures should just wire up
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* the individual syscalls instead.
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* This function handles System V IPC calls and routes them to appropriate kernel functions.
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* It supports backward compatibility and compatibility for different architectures.
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* New architectures should consider wiring up individual syscalls instead of using this.
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*/
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#include <linux/unistd.h>
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#include <linux/syscalls.h>
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#include <linux/security.h>
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@ -17,100 +19,92 @@
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#include <linux/shm.h>
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#include <linux/uaccess.h>
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struct ipc_kludge {
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void __user *msgp;
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long msgtyp;
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};
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/**
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* ksys_ipc - System V IPC syscall handler
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* @call: IPC call identifier
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* @first: First syscall argument
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* @second: Second syscall argument
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* @third: Third syscall argument
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* @ptr: Pointer to user data
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* @fifth: Fifth syscall argument
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*
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* This function handles System V IPC calls and routes them to appropriate kernel functions.
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*/
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int ksys_ipc(unsigned int call, int first, unsigned long second,
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unsigned long third, void __user * ptr, long fifth)
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unsigned long third, void __user *ptr, long fifth)
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{
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int version, ret;
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int ret = -ENOSYS; // Default to ENOSYS if syscall not implemented
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version = call >> 16; /* hack for backward compatibility */
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call &= 0xffff;
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switch (call) {
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case SEMOP:
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ret = ksys_semtimedop(first, (struct sembuf __user *)ptr, second, NULL);
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break;
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case SEMTIMEDOP:
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if (IS_ENABLED(CONFIG_64BIT))
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ret = ksys_semtimedop(first, ptr, second, (const struct __kernel_timespec __user *)fifth);
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else if (IS_ENABLED(CONFIG_COMPAT_32BIT_TIME))
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ret = compat_ksys_semtimedop(first, ptr, second, (const struct old_timespec32 __user *)fifth);
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break;
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case SEMGET:
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ret = ksys_semget(first, second, third);
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break;
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case SEMCTL:
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if (!ptr)
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ret = -EINVAL;
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else {
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unsigned long arg;
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if (get_user(arg, (unsigned long __user *)ptr))
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ret = -EFAULT;
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else
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ret = ksys_old_semctl(first, second, third, arg);
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}
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break;
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case MSGSND:
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ret = ksys_msgsnd(first, (struct msgbuf __user *)ptr, second, third);
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break;
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case MSGRCV: {
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struct ipc_kludge tmp;
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if (!ptr)
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return -EINVAL;
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if (copy_from_user(&tmp, (struct ipc_kludge __user *)ptr, sizeof(tmp)))
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return -EFAULT;
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return ksys_msgrcv(first, tmp.msgp, second, tmp.msgtyp, third);
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}
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case MSGGET:
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ret = ksys_msgget((key_t) first, second);
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break;
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case MSGCTL:
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ret = ksys_old_msgctl(first, second, (struct msqid_ds __user *)ptr);
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break;
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case SHMAT:
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ret = do_shmat_handler(call, first, second, third, ptr);
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break;
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case SHMDT:
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ret = ksys_shmdt((char __user *)ptr);
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break;
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case SHMGET:
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ret = ksys_shmget(first, (unsigned int)second, third);
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break;
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case SHMCTL:
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ret = ksys_old_shmctl(first, second, (struct shmid_ds __user *)ptr);
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break;
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default:
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ret = -ENOSYS;
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break;
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}
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switch (call) {
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case SEMOP:
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return ksys_semtimedop(first, (struct sembuf __user *)ptr,
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second, NULL);
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case SEMTIMEDOP:
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if (IS_ENABLED(CONFIG_64BIT))
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return ksys_semtimedop(first, ptr, second,
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(const struct __kernel_timespec __user *)fifth);
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else if (IS_ENABLED(CONFIG_COMPAT_32BIT_TIME))
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return compat_ksys_semtimedop(first, ptr, second,
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(const struct old_timespec32 __user *)fifth);
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else
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return -ENOSYS;
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case SEMGET:
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return ksys_semget(first, second, third);
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case SEMCTL: {
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unsigned long arg;
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if (!ptr)
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return -EINVAL;
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if (get_user(arg, (unsigned long __user *) ptr))
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return -EFAULT;
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return ksys_old_semctl(first, second, third, arg);
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}
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case MSGSND:
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return ksys_msgsnd(first, (struct msgbuf __user *) ptr,
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second, third);
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case MSGRCV:
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switch (version) {
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case 0: {
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struct ipc_kludge tmp;
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if (!ptr)
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return -EINVAL;
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if (copy_from_user(&tmp,
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(struct ipc_kludge __user *) ptr,
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sizeof(tmp)))
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return -EFAULT;
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return ksys_msgrcv(first, tmp.msgp, second,
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tmp.msgtyp, third);
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}
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default:
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return ksys_msgrcv(first,
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(struct msgbuf __user *) ptr,
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second, fifth, third);
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}
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case MSGGET:
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return ksys_msgget((key_t) first, second);
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case MSGCTL:
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return ksys_old_msgctl(first, second,
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(struct msqid_ds __user *)ptr);
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case SHMAT:
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switch (version) {
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default: {
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unsigned long raddr;
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ret = do_shmat(first, (char __user *)ptr,
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second, &raddr, SHMLBA);
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if (ret)
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return ret;
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return put_user(raddr, (unsigned long __user *) third);
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}
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case 1:
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/*
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* This was the entry point for kernel-originating calls
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* from iBCS2 in 2.2 days.
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*/
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return -EINVAL;
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}
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case SHMDT:
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return ksys_shmdt((char __user *)ptr);
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case SHMGET:
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return ksys_shmget(first, second, third);
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case SHMCTL:
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return ksys_old_shmctl(first, second,
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(struct shmid_ds __user *) ptr);
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default:
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return -ENOSYS;
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}
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return ret;
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}
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SYSCALL_DEFINE6(ipc, unsigned int, call, int, first, unsigned long, second,
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unsigned long, third, void __user *, ptr, long, fifth)
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unsigned long, third, void __user *, ptr, long, fifth)
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{
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return ksys_ipc(call, first, second, third, ptr, fifth);
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return ksys_ipc(call, first, second, third, ptr, fifth);
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}
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#endif
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@ -118,94 +112,100 @@ SYSCALL_DEFINE6(ipc, unsigned int, call, int, first, unsigned long, second,
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#include <linux/compat.h>
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#ifndef COMPAT_SHMLBA
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#define COMPAT_SHMLBA SHMLBA
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#define COMPAT_SHMLBA SHMLBA
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#endif
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struct compat_ipc_kludge {
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compat_uptr_t msgp;
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compat_long_t msgtyp;
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compat_uptr_t msgp;
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compat_long_t msgtyp;
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};
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#ifdef CONFIG_ARCH_WANT_OLD_COMPAT_IPC
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int compat_ksys_ipc(u32 call, int first, int second,
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u32 third, compat_uptr_t ptr, u32 fifth)
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u32 third, compat_uptr_t ptr, u32 fifth)
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{
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int version;
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u32 pad;
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int ret = -ENOSYS;
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int version;
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u32 pad;
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version = call >> 16; /* hack for backward compatibility */
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call &= 0xffff;
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version = call >> 16; /* hack for backward compatibility */
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call &= 0xffff;
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switch (call) {
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case SEMOP:
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/* struct sembuf is the same on 32 and 64bit :)) */
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return ksys_semtimedop(first, compat_ptr(ptr), second, NULL);
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case SEMTIMEDOP:
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if (!IS_ENABLED(CONFIG_COMPAT_32BIT_TIME))
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return -ENOSYS;
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return compat_ksys_semtimedop(first, compat_ptr(ptr), second,
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compat_ptr(fifth));
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case SEMGET:
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return ksys_semget(first, second, third);
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case SEMCTL:
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if (!ptr)
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return -EINVAL;
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if (get_user(pad, (u32 __user *) compat_ptr(ptr)))
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return -EFAULT;
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return compat_ksys_old_semctl(first, second, third, pad);
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switch (call) {
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case SEMOP:
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ret = ksys_semtimedop(first, compat_ptr(ptr), second, NULL);
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break;
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case SEMTIMEDOP:
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if (!IS_ENABLED(CONFIG_COMPAT_32BIT_TIME))
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return -ENOSYS;
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ret = compat_ksys_semtimedop(first, compat_ptr(ptr), second,
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compat_ptr(fifth));
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break;
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case SEMGET:
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ret = ksys_semget(first, second, third);
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break;
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case SEMCTL:
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if (!ptr)
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ret = -EINVAL;
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else {
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if (get_user(pad, (u32 __user *) compat_ptr(ptr)))
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ret = -EFAULT;
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else
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ret = compat_ksys_old_semctl(first, second, third, pad);
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}
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break;
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case MSGSND:
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ret = compat_ksys_msgsnd(first, ptr, second, third);
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break;
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case MSGRCV: {
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void __user *uptr = compat_ptr(ptr);
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case MSGSND:
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return compat_ksys_msgsnd(first, ptr, second, third);
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if (first < 0 || second < 0)
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return -EINVAL;
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case MSGRCV: {
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void __user *uptr = compat_ptr(ptr);
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if (!version) {
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struct compat_ipc_kludge ipck;
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if (!uptr)
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return -EINVAL;
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if (copy_from_user(&ipck, uptr, sizeof(ipck)))
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return -EFAULT;
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return compat_ksys_msgrcv(first, ipck.msgp, second,
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ipck.msgtyp, third);
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}
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return compat_ksys_msgrcv(first, ptr, second, fifth, third);
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}
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case MSGGET:
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ret = ksys_msgget(first, second);
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break;
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case MSGCTL:
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ret = compat_ksys_old_msgctl(first, second, compat_ptr(ptr));
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break;
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case SHMAT:
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if (version == 1)
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return -EINVAL;
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ret = do_shmat_handler(call, first, second, third, ptr);
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break;
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case SHMDT:
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ret = ksys_shmdt(compat_ptr(ptr));
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break;
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case SHMGET:
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ret = ksys_shmget(first, (unsigned int)second, third);
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break;
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case SHMCTL:
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ret = compat_ksys_old_shmctl(first, second, compat_ptr(ptr));
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break;
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default:
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ret = -ENOSYS;
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break;
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}
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if (first < 0 || second < 0)
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return -EINVAL;
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if (!version) {
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struct compat_ipc_kludge ipck;
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if (!uptr)
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return -EINVAL;
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if (copy_from_user(&ipck, uptr, sizeof(ipck)))
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return -EFAULT;
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return compat_ksys_msgrcv(first, ipck.msgp, second,
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ipck.msgtyp, third);
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}
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return compat_ksys_msgrcv(first, ptr, second, fifth, third);
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}
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case MSGGET:
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return ksys_msgget(first, second);
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case MSGCTL:
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return compat_ksys_old_msgctl(first, second, compat_ptr(ptr));
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case SHMAT: {
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int err;
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unsigned long raddr;
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if (version == 1)
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return -EINVAL;
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err = do_shmat(first, compat_ptr(ptr), second, &raddr,
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COMPAT_SHMLBA);
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if (err < 0)
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return err;
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return put_user(raddr, (compat_ulong_t __user *)compat_ptr(third));
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}
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case SHMDT:
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return ksys_shmdt(compat_ptr(ptr));
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case SHMGET:
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return ksys_shmget(first, (unsigned int)second, third);
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case SHMCTL:
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return compat_ksys_old_shmctl(first, second, compat_ptr(ptr));
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}
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return -ENOSYS;
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return ret;
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}
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COMPAT_SYSCALL_DEFINE6(ipc, u32, call, int, first, int, second,
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u32, third, compat_uptr_t, ptr, u32, fifth)
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u32, third, compat_uptr_t, ptr, u32, fifth)
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{
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return compat_ksys_ipc(call, first, second, third, ptr, fifth);
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return compat_ksys_ipc(call, first, second, third, ptr, fifth);
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}
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#endif
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#endif
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