// SPDX-License-Identifier: GPL-2.0/* * linux/kernel/sys.c * * Copyright (C) 1991, 1992 Linus Torvalds */ #include <linux/export.h>#include <linux/mm.h>#include <linux/mm_inline.h>#include <linux/utsname.h>#include <linux/mman.h>#include <linux/reboot.h>#include <linux/prctl.h>#include <linux/highuid.h>#include <linux/fs.h>#include <linux/kmod.h>#include <linux/ksm.h>#include <linux/perf_event.h>#include <linux/resource.h>#include <linux/kernel.h>#include <linux/workqueue.h>#include <linux/capability.h>#include <linux/device.h>#include <linux/key.h>#include <linux/times.h>#include <linux/posix-timers.h>#include <linux/security.h>#include <linux/random.h>#include <linux/suspend.h>#include <linux/tty.h>#include <linux/signal.h>#include <linux/cn_proc.h>#include <linux/getcpu.h>#include <linux/task_io_accounting_ops.h>#include <linux/seccomp.h>#include <linux/cpu.h>#include <linux/personality.h>#include <linux/ptrace.h>#include <linux/fs_struct.h>#include <linux/file.h>#include <linux/mount.h>#include <linux/gfp.h>#include <linux/syscore_ops.h>#include <linux/version.h>#include <linux/ctype.h>#include <linux/syscall_user_dispatch.h> #include <linux/compat.h>#include <linux/syscalls.h>#include <linux/kprobes.h>#include <linux/user_namespace.h>#include <linux/time_namespace.h>#include <linux/binfmts.h>#include <linux/futex.h> #include <linux/sched.h>#include <linux/sched/autogroup.h>#include <linux/sched/loadavg.h>#include <linux/sched/stat.h>#include <linux/sched/mm.h>#include <linux/sched/coredump.h>#include <linux/sched/task.h>#include <linux/sched/cputime.h>#include <linux/rcupdate.h>#include <linux/uidgid.h>#include <linux/cred.h> #include <linux/nospec.h> #include <linux/kmsg_dump.h>/* Move somewhere else to avoid recompiling? */#include <generated/utsrelease.h> #include <linux/uaccess.h>#include <asm/io.h>#include <asm/unistd.h> #include <trace/events/task.h> #include "uid16.h" #ifndef SET_UNALIGN_CTL# define SET_UNALIGN_CTL(a, b) (-EINVAL)#endif#ifndef GET_UNALIGN_CTL# define GET_UNALIGN_CTL(a, b) (-EINVAL)#endif#ifndef SET_FPEMU_CTL# define SET_FPEMU_CTL(a, b) (-EINVAL)#endif#ifndef GET_FPEMU_CTL# define GET_FPEMU_CTL(a, b) (-EINVAL)#endif#ifndef SET_FPEXC_CTL# define SET_FPEXC_CTL(a, b) (-EINVAL)#endif#ifndef GET_FPEXC_CTL# define GET_FPEXC_CTL(a, b) (-EINVAL)#endif#ifndef GET_ENDIAN# define GET_ENDIAN(a, b) (-EINVAL)#endif#ifndef SET_ENDIAN# define SET_ENDIAN(a, b) (-EINVAL)#endif#ifndef GET_TSC_CTL# define GET_TSC_CTL(a) (-EINVAL)#endif#ifndef SET_TSC_CTL# define SET_TSC_CTL(a) (-EINVAL)#endif#ifndef GET_FP_MODE# define GET_FP_MODE(a) (-EINVAL)#endif#ifndef SET_FP_MODE# define SET_FP_MODE(a,b) (-EINVAL)#endif#ifndef SVE_SET_VL# define SVE_SET_VL(a) (-EINVAL)#endif#ifndef SVE_GET_VL# define SVE_GET_VL() (-EINVAL)#endif#ifndef SME_SET_VL# define SME_SET_VL(a) (-EINVAL)#endif#ifndef SME_GET_VL# define SME_GET_VL() (-EINVAL)#endif#ifndef PAC_RESET_KEYS# define PAC_RESET_KEYS(a, b) (-EINVAL)#endif#ifndef PAC_SET_ENABLED_KEYS# define PAC_SET_ENABLED_KEYS(a, b, c) (-EINVAL)#endif#ifndef PAC_GET_ENABLED_KEYS# define PAC_GET_ENABLED_KEYS(a) (-EINVAL)#endif#ifndef SET_TAGGED_ADDR_CTRL# define SET_TAGGED_ADDR_CTRL(a) (-EINVAL)#endif#ifndef GET_TAGGED_ADDR_CTRL# define GET_TAGGED_ADDR_CTRL() (-EINVAL)#endif#ifndef RISCV_V_SET_CONTROL# define RISCV_V_SET_CONTROL(a) (-EINVAL)#endif#ifndef RISCV_V_GET_CONTROL# define RISCV_V_GET_CONTROL() (-EINVAL)#endif#ifndef RISCV_SET_ICACHE_FLUSH_CTX# define RISCV_SET_ICACHE_FLUSH_CTX(a, b) (-EINVAL)#endif#ifndef PPC_GET_DEXCR_ASPECT# define PPC_GET_DEXCR_ASPECT(a, b) (-EINVAL)#endif#ifndef PPC_SET_DEXCR_ASPECT# define PPC_SET_DEXCR_ASPECT(a, b, c) (-EINVAL)#endif /* * this is where the system-wide overflow UID and GID are defined, for * architectures that now have 32-bit UID/GID but didn't in the past */ int overflowuid = DEFAULT_OVERFLOWUID;int overflowgid = DEFAULT_OVERFLOWGID; EXPORT_SYMBOL(overflowuid);EXPORT_SYMBOL(overflowgid); /* * the same as above, but for filesystems which can only store a 16-bit * UID and GID. as such, this is needed on all architectures */ int fs_overflowuid = DEFAULT_FS_OVERFLOWUID;int fs_overflowgid = DEFAULT_FS_OVERFLOWGID; EXPORT_SYMBOL(fs_overflowuid);EXPORT_SYMBOL(fs_overflowgid); static const struct ctl_table overflow_sysctl_table[] = { { .procname = "overflowuid", .data = &overflowuid, .maxlen = sizeof(int), .mode = 0644, .proc_handler = proc_dointvec_minmax, .extra1 = SYSCTL_ZERO, .extra2 = SYSCTL_MAXOLDUID, }, { .procname = "overflowgid", .data = &overflowgid, .maxlen = sizeof(int), .mode = 0644, .proc_handler = proc_dointvec_minmax, .extra1 = SYSCTL_ZERO, .extra2 = SYSCTL_MAXOLDUID, },}; static int __init init_overflow_sysctl(void){ register_sysctl_init("kernel", overflow_sysctl_table); return 0;} postcore_initcall(init_overflow_sysctl); /* * Returns true if current's euid is same as p's uid or euid, * or has CAP_SYS_NICE to p's user_ns. * * Called with rcu_read_lock, creds are safe */static bool set_one_prio_perm(struct task_struct *p){ const struct cred *cred = current_cred(), *pcred = __task_cred(p); if (uid_eq(pcred->uid, cred->euid) || uid_eq(pcred->euid, cred->euid)) return true; if (ns_capable(pcred->user_ns, CAP_SYS_NICE)) return true; return false;} /* * set the priority of a task * - the caller must hold the RCU read lock */static int set_one_prio(struct task_struct *p, int niceval, int error){ int no_nice; if (!set_one_prio_perm(p)) { error = -EPERM; goto out; } if (niceval < task_nice(p) && !can_nice(p, niceval)) { error = -EACCES; goto out; } no_nice = security_task_setnice(p, niceval); if (no_nice) { error = no_nice; goto out; } if (error == -ESRCH) error = 0; set_user_nice(p, niceval);out: return error;} SYSCALL_DEFINE3(setpriority, int, which, int, who, int, niceval){ struct task_struct *g, *p; struct user_struct *user; const struct cred *cred = current_cred(); int error = -EINVAL; struct pid *pgrp; kuid_t uid; if (which > PRIO_USER || which < PRIO_PROCESS) goto out; /* normalize: avoid signed division (rounding problems) */ error = -ESRCH; if (niceval < MIN_NICE) niceval = MIN_NICE; if (niceval > MAX_NICE) niceval = MAX_NICE; rcu_read_lock(); switch (which) { case PRIO_PROCESS: if (who) p = find_task_by_vpid(who); else p = current; if (p) error = set_one_prio(p, niceval, error); break; case PRIO_PGRP: if (who) pgrp = find_vpid(who); else pgrp = task_pgrp(current); read_lock(&tasklist_lock); do_each_pid_thread(pgrp, PIDTYPE_PGID, p) { error = set_one_prio(p, niceval, error); } while_each_pid_thread(pgrp, PIDTYPE_PGID, p); read_unlock(&tasklist_lock); break; case PRIO_USER: uid = make_kuid(cred->user_ns, who); user = cred->user; if (!who) uid = cred->uid; else if (!uid_eq(uid, cred->uid)) { user = find_user(uid); if (!user) goto out_unlock; /* No processes for this user */ } for_each_process_thread(g, p) { if (uid_eq(task_uid(p), uid) && task_pid_vnr(p)) error = set_one_prio(p, niceval, error); } if (!uid_eq(uid, cred->uid)) free_uid(user); /* For find_user() */ break; }out_unlock: rcu_read_unlock();out: return error;} /* * Ugh. To avoid negative return values, "getpriority()" will * not return the normal nice-value, but a negated value that * has been offset by 20 (ie it returns 40..1 instead of -20..19) * to stay compatible. */SYSCALL_DEFINE2(getpriority, int, which, int, who){ struct task_struct *g, *p; struct user_struct *user; const struct cred *cred = current_cred(); long niceval, retval = -ESRCH; struct pid *pgrp; kuid_t uid; if (which > PRIO_USER || which < PRIO_PROCESS) return -EINVAL; rcu_read_lock(); switch (which) { case PRIO_PROCESS: if (who) p = find_task_by_vpid(who); else p = current; if (p) { niceval = nice_to_rlimit(task_nice(p)); if (niceval > retval) retval = niceval; } break; case PRIO_PGRP: if (who) pgrp = find_vpid(who); else pgrp = task_pgrp(current); read_lock(&tasklist_lock); do_each_pid_thread(pgrp, PIDTYPE_PGID, p) { niceval = nice_to_rlimit(task_nice(p)); if (niceval > retval) retval = niceval; } while_each_pid_thread(pgrp, PIDTYPE_PGID, p); read_unlock(&tasklist_lock); break; case PRIO_USER: uid = make_kuid(cred->user_ns, who); user = cred->user; if (!who) uid = cred->uid; else if (!uid_eq(uid, cred->uid)) { user = find_user(uid); if (!user) goto out_unlock; /* No processes for this user */ } for_each_process_thread(g, p) { if (uid_eq(task_uid(p), uid) && task_pid_vnr(p)) { niceval = nice_to_rlimit(task_nice(p)); if (niceval > retval) retval = niceval; } } if (!uid_eq(uid, cred->uid)) free_uid(user); /* for find_user() */ break; }out_unlock: rcu_read_unlock(); return retval;} /* * Unprivileged users may change the real gid to the effective gid * or vice versa. (BSD-style) * * If you set the real gid at all, or set the effective gid to a value not * equal to the real gid, then the saved gid is set to the new effective gid. * * This makes it possible for a setgid program to completely drop its * privileges, which is often a useful assertion to make when you are doing * a security audit over a program. * * The general idea is that a program which uses just setregid() will be * 100% compatible with BSD. A program which uses just setgid() will be * 100% compatible with POSIX with saved IDs. * * SMP: There are not races, the GIDs are checked only by filesystem * operations (as far as semantic preservation is concerned). */#ifdef CONFIG_MULTIUSERlong __sys_setregid(gid_t rgid, gid_t egid){ struct user_namespace *ns = current_user_ns(); const struct cred *old; struct cred *new; int retval; kgid_t krgid, kegid; krgid = make_kgid(ns, rgid); kegid = make_kgid(ns, egid); if ((rgid != (gid_t) -1) && !gid_valid(krgid)) return -EINVAL; if ((egid != (gid_t) -1) && !gid_valid(kegid)) return -EINVAL; new = prepare_creds(); if (!new) return -ENOMEM; old = current_cred(); retval = -EPERM; if (rgid != (gid_t) -1) { if (gid_eq(old->gid, krgid) || gid_eq(old->egid, krgid) || ns_capable_setid(old->user_ns, CAP_SETGID)) new->gid = krgid; else goto error; } if (egid != (gid_t) -1) { if (gid_eq(old->gid, kegid) || gid_eq(old->egid, kegid) || gid_eq(old->sgid, kegid) || ns_capable_setid(old->user_ns, CAP_SETGID)) new->egid = kegid; else goto error; } if (rgid != (gid_t) -1 || (egid != (gid_t) -1 && !gid_eq(kegid, old->gid))) new->sgid = new->egid; new->fsgid = new->egid; retval = security_task_fix_setgid(new, old, LSM_SETID_RE); if (retval < 0) goto error; return commit_creds(new); error: abort_creds(new); return retval;} SYSCALL_DEFINE2(setregid, gid_t, rgid, gid_t, egid){ return __sys_setregid(rgid, egid);} /* * setgid() is implemented like SysV w/ SAVED_IDS * * SMP: Same implicit races as above. */long __sys_setgid(gid_t gid){ struct user_namespace *ns = current_user_ns(); const struct cred *old; struct cred *new; int retval; kgid_t kgid; kgid = make_kgid(ns, gid); if (!gid_valid(kgid)) return -EINVAL; new = prepare_creds(); if (!new) return -ENOMEM; old = current_cred(); retval = -EPERM; if (ns_capable_setid(old->user_ns, CAP_SETGID)) new->gid = new->egid = new->sgid = new->fsgid = kgid; else if (gid_eq(kgid, old->gid) || gid_eq(kgid, old->sgid)) new->egid = new->fsgid = kgid;Lines 1–500 of 3036. Load more
// SPDX-License-Identifier: GPL-2.0 /* * linux/kernel/sys.c * * Copyright (C) 1991, 1992 Linus Torvalds */ #include <linux/export.h> #include <linux/mm.h> #include <linux/mm_inline.h> #include <linux/utsname.h> #include <linux/mman.h> #include <linux/reboot.h> #include <linux/prctl.h> #include <linux/highuid.h> #include <linux/fs.h> #include <linux/kmod.h> #include <linux/ksm.h> #include <linux/perf_event.h> #include <linux/resource.h> #include <linux/kernel.h> #include <linux/workqueue.h> #include <linux/capability.h> #include <linux/device.h> #include <linux/key.h> #include <linux/times.h> #include <linux/posix-timers.h> #include <linux/security.h> #include <linux/random.h> #include <linux/suspend.h> #include <linux/tty.h> #include <linux/signal.h> #include <linux/cn_proc.h> #include <linux/getcpu.h> #include <linux/task_io_accounting_ops.h> #include <linux/seccomp.h> #include <linux/cpu.h> #include <linux/personality.h> #include <linux/ptrace.h> #include <linux/fs_struct.h> #include <linux/file.h> #include <linux/mount.h> #include <linux/gfp.h> #include <linux/syscore_ops.h> #include <linux/version.h> #include <linux/ctype.h> #include <linux/syscall_user_dispatch.h> #include <linux/compat.h> #include <linux/syscalls.h> #include <linux/kprobes.h> #include <linux/user_namespace.h> #include <linux/time_namespace.h> #include <linux/binfmts.h> #include <linux/futex.h> #include <linux/sched.h> #include <linux/sched/autogroup.h> #include <linux/sched/loadavg.h> #include <linux/sched/stat.h> #include <linux/sched/mm.h> #include <linux/sched/coredump.h> #include <linux/sched/task.h> #include <linux/sched/cputime.h> #include <linux/rcupdate.h> #include <linux/uidgid.h> #include <linux/cred.h> #include <linux/nospec.h> #include <linux/kmsg_dump.h> /* Move somewhere else to avoid recompiling? */ #include <generated/utsrelease.h> #include <linux/uaccess.h> #include <asm/io.h> #include <asm/unistd.h> #include <trace/events/task.h> #include "uid16.h" #ifndef SET_UNALIGN_CTL # define SET_UNALIGN_CTL(a, b) (-EINVAL) #endif #ifndef GET_UNALIGN_CTL # define GET_UNALIGN_CTL(a, b) (-EINVAL) #endif #ifndef SET_FPEMU_CTL # define SET_FPEMU_CTL(a, b) (-EINVAL) #endif #ifndef GET_FPEMU_CTL # define GET_FPEMU_CTL(a, b) (-EINVAL) #endif #ifndef SET_FPEXC_CTL # define SET_FPEXC_CTL(a, b) (-EINVAL) #endif #ifndef GET_FPEXC_CTL # define GET_FPEXC_CTL(a, b) (-EINVAL) #endif #ifndef GET_ENDIAN # define GET_ENDIAN(a, b) (-EINVAL) #endif #ifndef SET_ENDIAN # define SET_ENDIAN(a, b) (-EINVAL) #endif #ifndef GET_TSC_CTL # define GET_TSC_CTL(a) (-EINVAL) #endif #ifndef SET_TSC_CTL # define SET_TSC_CTL(a) (-EINVAL) #endif #ifndef GET_FP_MODE # define GET_FP_MODE(a) (-EINVAL) #endif #ifndef SET_FP_MODE # define SET_FP_MODE(a,b) (-EINVAL) #endif #ifndef SVE_SET_VL # define SVE_SET_VL(a) (-EINVAL) #endif #ifndef SVE_GET_VL # define SVE_GET_VL() (-EINVAL) #endif #ifndef SME_SET_VL # define SME_SET_VL(a) (-EINVAL) #endif #ifndef SME_GET_VL # define SME_GET_VL() (-EINVAL) #endif #ifndef PAC_RESET_KEYS # define PAC_RESET_KEYS(a, b) (-EINVAL) #endif #ifndef PAC_SET_ENABLED_KEYS # define PAC_SET_ENABLED_KEYS(a, b, c) (-EINVAL) #endif #ifndef PAC_GET_ENABLED_KEYS # define PAC_GET_ENABLED_KEYS(a) (-EINVAL) #endif #ifndef SET_TAGGED_ADDR_CTRL # define SET_TAGGED_ADDR_CTRL(a) (-EINVAL) #endif #ifndef GET_TAGGED_ADDR_CTRL # define GET_TAGGED_ADDR_CTRL() (-EINVAL) #endif #ifndef RISCV_V_SET_CONTROL # define RISCV_V_SET_CONTROL(a) (-EINVAL) #endif #ifndef RISCV_V_GET_CONTROL # define RISCV_V_GET_CONTROL() (-EINVAL) #endif #ifndef RISCV_SET_ICACHE_FLUSH_CTX # define RISCV_SET_ICACHE_FLUSH_CTX(a, b) (-EINVAL) #endif #ifndef PPC_GET_DEXCR_ASPECT # define PPC_GET_DEXCR_ASPECT(a, b) (-EINVAL) #endif #ifndef PPC_SET_DEXCR_ASPECT # define PPC_SET_DEXCR_ASPECT(a, b, c) (-EINVAL) #endif /* * this is where the system-wide overflow UID and GID are defined, for * architectures that now have 32-bit UID/GID but didn't in the past */ int overflowuid = DEFAULT_OVERFLOWUID; int overflowgid = DEFAULT_OVERFLOWGID; EXPORT_SYMBOL(overflowuid); EXPORT_SYMBOL(overflowgid); /* * the same as above, but for filesystems which can only store a 16-bit * UID and GID. as such, this is needed on all architectures */ int fs_overflowuid = DEFAULT_FS_OVERFLOWUID; int fs_overflowgid = DEFAULT_FS_OVERFLOWGID; EXPORT_SYMBOL(fs_overflowuid); EXPORT_SYMBOL(fs_overflowgid); static const struct ctl_table overflow_sysctl_table[] = { { .procname = "overflowuid", .data = &overflowuid, .maxlen = sizeof(int), .mode = 0644, .proc_handler = proc_dointvec_minmax, .extra1 = SYSCTL_ZERO, .extra2 = SYSCTL_MAXOLDUID, }, { .procname = "overflowgid", .data = &overflowgid, .maxlen = sizeof(int), .mode = 0644, .proc_handler = proc_dointvec_minmax, .extra1 = SYSCTL_ZERO, .extra2 = SYSCTL_MAXOLDUID, }, }; static int __init init_overflow_sysctl(void) { register_sysctl_init("kernel", overflow_sysctl_table); return 0; } postcore_initcall(init_overflow_sysctl); /* * Returns true if current's euid is same as p's uid or euid, * or has CAP_SYS_NICE to p's user_ns. * * Called with rcu_read_lock, creds are safe */ static bool set_one_prio_perm(struct task_struct *p) { const struct cred *cred = current_cred(), *pcred = __task_cred(p); if (uid_eq(pcred->uid, cred->euid) || uid_eq(pcred->euid, cred->euid)) return true; if (ns_capable(pcred->user_ns, CAP_SYS_NICE)) return true; return false; } /* * set the priority of a task * - the caller must hold the RCU read lock */ static int set_one_prio(struct task_struct *p, int niceval, int error) { int no_nice; if (!set_one_prio_perm(p)) { error = -EPERM; goto out; } if (niceval < task_nice(p) && !can_nice(p, niceval)) { error = -EACCES; goto out; } no_nice = security_task_setnice(p, niceval); if (no_nice) { error = no_nice; goto out; } if (error == -ESRCH) error = 0; set_user_nice(p, niceval); out: return error; } SYSCALL_DEFINE3(setpriority, int, which, int, who, int, niceval) { struct task_struct *g, *p; struct user_struct *user; const struct cred *cred = current_cred(); int error = -EINVAL; struct pid *pgrp; kuid_t uid; if (which > PRIO_USER || which < PRIO_PROCESS) goto out; /* normalize: avoid signed division (rounding problems) */ error = -ESRCH; if (niceval < MIN_NICE) niceval = MIN_NICE; if (niceval > MAX_NICE) niceval = MAX_NICE; rcu_read_lock(); switch (which) { case PRIO_PROCESS: if (who) p = find_task_by_vpid(who); else p = current; if (p) error = set_one_prio(p, niceval, error); break; case PRIO_PGRP: if (who) pgrp = find_vpid(who); else pgrp = task_pgrp(current); read_lock(&tasklist_lock); do_each_pid_thread(pgrp, PIDTYPE_PGID, p) { error = set_one_prio(p, niceval, error); } while_each_pid_thread(pgrp, PIDTYPE_PGID, p); read_unlock(&tasklist_lock); break; case PRIO_USER: uid = make_kuid(cred->user_ns, who); user = cred->user; if (!who) uid = cred->uid; else if (!uid_eq(uid, cred->uid)) { user = find_user(uid); if (!user) goto out_unlock; /* No processes for this user */ } for_each_process_thread(g, p) { if (uid_eq(task_uid(p), uid) && task_pid_vnr(p)) error = set_one_prio(p, niceval, error); } if (!uid_eq(uid, cred->uid)) free_uid(user); /* For find_user() */ break; } out_unlock: rcu_read_unlock(); out: return error; } /* * Ugh. To avoid negative return values, "getpriority()" will * not return the normal nice-value, but a negated value that * has been offset by 20 (ie it returns 40..1 instead of -20..19) * to stay compatible. */ SYSCALL_DEFINE2(getpriority, int, which, int, who) { struct task_struct *g, *p; struct user_struct *user; const struct cred *cred = current_cred(); long niceval, retval = -ESRCH; struct pid *pgrp; kuid_t uid; if (which > PRIO_USER || which < PRIO_PROCESS) return -EINVAL; rcu_read_lock(); switch (which) { case PRIO_PROCESS: if (who) p = find_task_by_vpid(who); else p = current; if (p) { niceval = nice_to_rlimit(task_nice(p)); if (niceval > retval) retval = niceval; } break; case PRIO_PGRP: if (who) pgrp = find_vpid(who); else pgrp = task_pgrp(current); read_lock(&tasklist_lock); do_each_pid_thread(pgrp, PIDTYPE_PGID, p) { niceval = nice_to_rlimit(task_nice(p)); if (niceval > retval) retval = niceval; } while_each_pid_thread(pgrp, PIDTYPE_PGID, p); read_unlock(&tasklist_lock); break; case PRIO_USER: uid = make_kuid(cred->user_ns, who); user = cred->user; if (!who) uid = cred->uid; else if (!uid_eq(uid, cred->uid)) { user = find_user(uid); if (!user) goto out_unlock; /* No processes for this user */ } for_each_process_thread(g, p) { if (uid_eq(task_uid(p), uid) && task_pid_vnr(p)) { niceval = nice_to_rlimit(task_nice(p)); if (niceval > retval) retval = niceval; } } if (!uid_eq(uid, cred->uid)) free_uid(user); /* for find_user() */ break; } out_unlock: rcu_read_unlock(); return retval; } /* * Unprivileged users may change the real gid to the effective gid * or vice versa. (BSD-style) * * If you set the real gid at all, or set the effective gid to a value not * equal to the real gid, then the saved gid is set to the new effective gid. * * This makes it possible for a setgid program to completely drop its * privileges, which is often a useful assertion to make when you are doing * a security audit over a program. * * The general idea is that a program which uses just setregid() will be * 100% compatible with BSD. A program which uses just setgid() will be * 100% compatible with POSIX with saved IDs. * * SMP: There are not races, the GIDs are checked only by filesystem * operations (as far as semantic preservation is concerned). */ #ifdef CONFIG_MULTIUSER long __sys_setregid(gid_t rgid, gid_t egid) { struct user_namespace *ns = current_user_ns(); const struct cred *old; struct cred *new; int retval; kgid_t krgid, kegid; krgid = make_kgid(ns, rgid); kegid = make_kgid(ns, egid); if ((rgid != (gid_t) -1) && !gid_valid(krgid)) return -EINVAL; if ((egid != (gid_t) -1) && !gid_valid(kegid)) return -EINVAL; new = prepare_creds(); if (!new) return -ENOMEM; old = current_cred(); retval = -EPERM; if (rgid != (gid_t) -1) { if (gid_eq(old->gid, krgid) || gid_eq(old->egid, krgid) || ns_capable_setid(old->user_ns, CAP_SETGID)) new->gid = krgid; else goto error; } if (egid != (gid_t) -1) { if (gid_eq(old->gid, kegid) || gid_eq(old->egid, kegid) || gid_eq(old->sgid, kegid) || ns_capable_setid(old->user_ns, CAP_SETGID)) new->egid = kegid; else goto error; } if (rgid != (gid_t) -1 || (egid != (gid_t) -1 && !gid_eq(kegid, old->gid))) new->sgid = new->egid; new->fsgid = new->egid; retval = security_task_fix_setgid(new, old, LSM_SETID_RE); if (retval < 0) goto error; return commit_creds(new); error: abort_creds(new); return retval; } SYSCALL_DEFINE2(setregid, gid_t, rgid, gid_t, egid) { return __sys_setregid(rgid, egid); } /* * setgid() is implemented like SysV w/ SAVED_IDS * * SMP: Same implicit races as above. */ long __sys_setgid(gid_t gid) { struct user_namespace *ns = current_user_ns(); const struct cred *old; struct cred *new; int retval; kgid_t kgid; kgid = make_kgid(ns, gid); if (!gid_valid(kgid)) return -EINVAL; new = prepare_creds(); if (!new) return -ENOMEM; old = current_cred(); retval = -EPERM; if (ns_capable_setid(old->user_ns, CAP_SETGID)) new->gid = new->egid = new->sgid = new->fsgid = kgid; else if (gid_eq(kgid, old->gid) || gid_eq(kgid, old->sgid)) new->egid = new->fsgid = kgid;